Friday, March 16, 2012

Mammology

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Mammalogy


Kingdom Animalia


Phylum Chordata


-Subphylum Vertebrata (Craniata)


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-Class Mammalia


Endothermic vertebrates with hair, mammary glands, middle ear bones and other unifying features (see p. 5) Enucleate red blood cells, muscular diaphragm


-Dentary squamosal jaw articulation


4 major themes in this book (and mamalogy)


1. Evolution


. Scientific investigation


. Mammalian diversity


4. Form and Function


The field of mammalogy can be approached from many directions


-ecosystem -as a resource


-cellular -we are mammals


-etc. -behavior


Chapter History of Mammalogy


Starts, we assume with prehistoric humans and other hominids


-mammals were food


-mammals were predators


-eventually, mammals were domesticated


-mammals were even the subject of worships and religious rituals


Whereas mammalogy had its beginnings in prehistory, as a scientific field we can trace it back to the Greek and Roman Philosophers.


-Hippocrates (460-77BC)


-Aristotle (84-BC)


-grouped animal “forms” and recognized whales and humans as mammals along with horses, cows, sheep, etc.


Along with Pliny the Elder (-7AD) Aristotle formed much of what was known about mammals (including mammals that do not and did not exist) well into the Middle Ages.


Galen (AD 10-01) was am early Roman anatomist and probably one of the 1st to dissect mammals for scientific purpose.


Mammalogy (and other sciences) did not advance much until at least the 100’s and not substantially until the 1500’s with the exploration of the world be the Europeans


Mark Catesby (168-174) described many of the mammals in the English colonies in what is now the SE US and Bahamas


Georges Buffon (1707-1788) a Frenchman compiled (but did not actually write much of) the 44 vol. “Histoire Naturalle” in which he attempted to assemble all known facts about all animals


Modern Taxonomy also had its beginnings during this time.





John Ray (167-1705) an Englishman defined a species and may have come up with an early form of the system Linnaeus popularized and developed.


Carl von Linni (Carolus Linnaeus 1707-78) a Swedish botanist, is credited with developing the binomial system of nomenclature we use today.


-His 10th ed. of “Systema Naturae” (1758) forms the basis for modern taxonomy


-Also these species were grouped into a hierarchical arrangement species into genera, genera into families etc.


-Many Naturalists were working throughout the worked. In North America, as young country began to expand, expeditious were sent out to map and explore the west.


Thomas Jefferson (174-186) sent out one of the most important expeditions (1774-180) Meriwether Lewis and William Clark (1770-188) in 1804-1806.


-Lewis and Clark discovered and brought back many new organisms, including mammals.


Mammals that Lewis and Clark


“Discovered” included


-Not really but brought to the attention of science


-pronghorn, grizzly bear, and prairie dogs


Also sent by Jefferson- Zebulon Pike (177-181) traveled throughout the west and southwest and actually was far more famous in his day than Lewis and Clark.


Trappers, fur traders, army officers, and RR people all contributed to early mammalogy in the North America.


Many of these early records, particularly those of the fur trading companies, are invaluable data bases even today!


Thomas Say (1787-184) was a surgeon naturalist on several army expeditions.


Spencer Fullerton Baird (18-1887) was associated with the R’s and helped found the US National Museum (Smithsonian) and published a very important monograph.


-“General Report on North American Mammals” (185)


-Descriptions of 70+sp. of mammals.


C. Hart Merriam (1855-14) initiated a publication; “North American Fauna” refined techniques in mammalian taxonomy (including emphasis on cranial traits and teeth), helped form the Bureau of Biological Surveys (105) and served as the 1st president of the American Soc. Of Mammalogists it was formed in 11.


Museums have been important to mammalogy since the earliest times (e.g. the great natural history museums of Europe) and continue to be important centers of study.


“Our ability to study various mammalian systems or to work on the systematic and phylogeny of a particular group of mammals depends on the continued existence and mainterrance of these museum collections.” p.17


Charles Darwin (180-188) while not considered a mammalogist, contributed greatly to mammlaogy through his collections and through his theory of evolution through natural selection (1858) (which was indendently developed by Alfred Russell Wallace 18-11) considered to be the father of modern geology.


Emergence of Mammalogy as a Science


-As I have already discussed began with the Greek Philosophers.


-HOWEVER, clean up to the 1800’s most scientists studied multiple taxa and it really wasn’t until the late 1800’s and early 100’s that mammalogy emerged as a distinct discipline.


American Soc. of Mammalogist was formed in 11.


-Most centers of mammalogy formed around major museums at Harvard, Yale, Michigan, Cornell, Kansas, Texas Tech, and UC Berkeley.


Joseph Grinnell (1877-1) was at VC Berkeley


-Prime force in mammalogy and W.J Hamilton (10-10) at Cornell


As the 0th Century progressed, mammalogy moved out of the museums into many different areas.


-Medicine, game mgmt, behavior, ecology, conservation, genetics, physiology, etc.


-Medicine, and game mgmt nothing new


Chapter Methods and Techniques


We will go over this chapter in the Lab.


Chapter 4 Evolution and Dental Characteristics


Mammals evolved from reptilian ancestors during the 100 million year period from the late Paleozoic to the early Mesozoic era.


-See the time line Table 4.1 to put it into perspective.


Mammals came from synapid (S.C) reptiles that 1st appeared in the late Paleozoic (~0-mya) in N.A.


- Major orders


-Pelycosauria


-Therapsida- mammals come from these


-See Fig. 4. and 4.1


The Pelycosaurs were common and relatively diverse and included both carnivorous and herbivorous forms.


-One suborder, Sphenacodontia, which included the famous sail back “dinosaurs” (not really dinosaurian) such as Dimetrodon is believed to have given rise to the Therapsida sometime during the Permian, which eventually replace the Pelycosours and were much more mammal-like


The Therapsida can be divided into suborders


-Anomodontia- were the dominant terrestrial herbivores for 60 million years


-Theriodontia- primarily carnivorous and much more diverse than anonrodaonts


-Included the very successful Cynodontia which gave rise mammalian


-had a secondary palate and complex cheek teeth


Cynodontia existed for ~70 million years from Triassic to Jurassic periods and diversified into both carnivorous and herbivorous forms.


-Cynodonts share many features with mammals including


1. Tricuspid Vdentition and double rooted


. Jaw structure- increases dentary size


. Modification of 1st vertebrae into the atlas/axis complex


4. Similar phalanges and many others


-Also, more erect posture legs underneath rather than sprawling movement


-Increased adaptability in feeding


Life other vertebrates, the story of mammals is one of locomotion and feeding.


The transition between the mammal-like reptiles and mammals is fairly well-documented in the fossil record through tooth, jaw, and cranial elements


-For example, in reptiles and mammal-like reptiles, jaw, and articular bones.


-See p.5 Table 4. Comparison of Reptiles and Mammals


-Late an additional joint formed between the cranial squamosal and the surangular bones of the jaw.


The changes in jaw articulation were concurrent with changes in ear structure particularly middle ear bones membrane to inner ear. Mallwus is derived from the articular bone Incus is derived from the quadrate.


There are Alternative Hypothesis for the origins of mammals Fig. 4.7


Mammals may be monphyletic or polyphyletic (if we believe the Monotremes arose independently).


The 1st mammals (p.48)


-Remember, by most accounts (unless you are an extreme supporter of punctuated equilibrium) the transition from reptiles to mammals was gradual.


But once we have something defined as a mammal (dentary- squamosal jaw art.) what were these early mammals like?


-For the most part, during their 1st 100 million years, mammals were a rare and insignificant part of the terrestrial fauna.


-They were small (usually smaller than modern squirrels), uncommon (relatively)


and probably nocturnal.


-Very little niche overlap between these early mammals and the dinosaurs. E.g. mammals and the dinosaurs were larger than the largest mam. for ~140 million years and it wasn’t until the extinction of the dinos. That mammals grew to larger sizes and diversified.


-Talk about niche overlap and competitive exclusion.


The classification and relationships among the early mammalian Mesozoic groups is uncertain (see Fig. 4.8 and Table 4.)


“Prototheria”- considered a subclass by some and Order Monotremata is often placed in here, although there is no clear evidence that they belong here (see Fig. 4.8, Table 4. and p.170).


Several important early Prototheria include


-Morganucodontids- may have been ancestral to monotrium


-Triconodonta- includes, small carnivores teeth similar to later therians


-Docodonta- probably omnivores


-Multituberculata


-had rodent-like incisors


-herbivores


These are all mammals


-Although they had both a dentary-squamosal and quadrate articular jaw articulations


-Cheek teeth differentiated into premolars and molars


Theria


-Arose at the same time as the Prototheria (Triassic) see Fig. 4.8


-Order Symmetrodonta (Kuehneotheriidae) was probably a sister group to the Prototherian Morganucodontids.


-Camivores and insectivores


-Often called “Pantothesis”


-Order Eupantotheria- omnivores


“A significant feature of pantotheres was their molars, which had principal cusps in triangular arrangement (a tribosphenic molar- the basic pattern for most later mammals)


Advanced therrans probably originated from the eupantothere family Peramuridae middle Cretaceous.


Tribosphenic Molars


-Early mammals as well as some of their synapsid reptile ancestors, had tooth cusps arranged longitudinally.


The Therians have a tribosphenic (tutubercular) molar which allowed for both shearing and grinding of food.


See Fig. 4.10


-Upper molar has cusps collectively called the Trigon (Fig. 4.10 C&D)


-Lower molar has also has cusps (known as Trigonid, Fig 4.10A) but also has a “heel” or shelf called the Talonid (Fig 4.10 A&B)


There can also be smaller “accessory” cusps in addition to the # main cusps.


“During occlusion, a crushing or grinding action occurs as the protocone of upper molar contacts the talonid basin of the lower molar. Food is not only crushed but also sheared.


This is believed to be the ancestral condition and can still be seen in some marsupials and insectivores, but has been highly modified (derived) in other mammals.”


For example with the addition of a 4th cusp, molars of many modern mammals (humans) have become squarer.


-quadritubercular


-these teeth allowed much more efficient processing of food necessary for endothermy.


-modified in most groups


The great diversity of modern mammals (metatherians and cutherians) had its beginnings in the early Cenozoic era.


WHY?


Major Events


1. Extinction of dinosaurs


-Opened new “adaptive opportunity”


. Brealcup of Pangea


-Continental drift allowed major genetic differentiation of the various phylogenetic lineages to proceed in relative isolation (See Fig. 4.11)


Other factors also important e.g. floral diversity also increased at this time.


Most modern families date from before the Miocene


As stated earlier, most of the mammalians adaptations relate to feeding and locomotion; However, these factors in turn are related to endothermy and its increased metabolic demands. Mammals necd ~10x more food and O.


Look over the summary and comparison of mammal-like reptiles and mammals on p.5- and Table 4..


Biology and Ecology


We will go into some of the characteristics of modern mammals in a little more detail now in the rest of Chapter 4 and in the following chapter on


-Integument, support, and movement (chp.5)


-Food and deeding (6)


-Nervous and endocrine systems (7)


-Adaptations to a wide variety of environments (8)


-Reproduction ()


Dentition


“Teeth are one of the most important aspects of living (and extinct) mammals.”


Occur in bones


-Premaxilla


-Maxilla


-Dentary


Tooth morphology- See Fig. 4.17, p.56


-Crown-above gum line


-Roots- below “ “ surrounded by cementum- has annli


-Enamel overlays dentine


-One of the hardest vertebrate tissues


-Crystalized calcium phosphate


-Dermal-Dentine


-Rodents have enamel only on anterior surface


Pulp cavity within dentine has blood and verves


-Open (ever growing) vs closed (stop growing) rooted teeth


Tooth socket is an aloveolus


Edentate mammals often have teeth develop and resorb as embryos


We went over the types of teeth in lab- incisors, canines, premolars, and molars.


The hete4rodont dentition of most mammals is highly variable.


Crown Height


-Low crowns- brachyodont (omnivores and carnivores)


-High crowns-hypsodont (herbivores)


Occlusal surfaces


-Bunodont- rounded cusps


-Lophodont- continues ridges or lophs


-Selenodont- lophs isolated and crescent shaped


-Carnassial (sectorial) teeth- shearing cutting


-Last upper premolar,1st lower molar


Usually when one set of teeth is being used, the others are not (e.g. when an animal chews with cheek-teeth its incisors do not come together)


WHY?


-Gays in teeth (i.e. lost teeth)-diastema


Diphyodont


Mammals usually have sets of teeth- “middle” teeth are deciduous and replaced by permanent ones


-In most, replacement is vertical, but in elephants and manatees tooth replacement is horizontal.


Dental formulas- went over this in Lab.


-In eutherians the ancestral formula is /, 1/1, 4/4, / = 44


-Metatherians- 5/4 1/1 / 4/4 = 50


END OF UNIT 1


UNIT


Structure (form) and function


Integument- adapted for;


1. Need to retain HO


. Need to retain body heat


Also serves a variety of other functions


-Protection


-Camouflage


-Behavior and sexual selection


-Secretes scents, oils, HO, and milk


-Others


See Fig. 5.


Consists of outer epidermis (ectodermal origin) inner dermis (mesodermal origin) and the innermost hypodermis or subcutaneous region.


Epidermis consists of layers (listed outer to inner)


1. Stratum corneum- mostly dead keratinized or cornified cells


-Responds to use and abrasion and is therefore thicker in some regions.


-Glands originate have through invagination but often end up in dermis Called A. basale in Fig. 5.


. Stratum granulosum- keratinization trappens here


. Stratum germanitavium


-Cells actively dividing in this region


No Blood Vessels


Basement membrane separates dermis from epid.


-E.g. paietae, frontae, premax, marilla, dentary


Dermis


-Fibrous connective tissue (mostly collgen fiben)


-Blood vessels, nerves, and smooth muscle


-Dermal bones (living armadillo, some extinct mammals.


-Shull pectoral girdle e.g. clavicle


Modes of Locomotion (6 Major categories)


1. Walking and running


-Cursorial-running


-Ambulatory-walking


. Jumping


-Saltatorial-jumping (rely on elasticity of tendons) store energy


. Swimming


4. Flying and gliding


-Volant (true powered flight)


-Gliding


5. Climbing


-Brachiation (swinging from branch to branch with arms)


-Climbing (prehensile tails and hands/feet


6. Fossorial digging/burrowing


The skeletomuscular system is highly adapted for each form of locomotion.


-Give examples from book


Chapter 6 Foods and Feeding


As we have already discussed, endothermy requires more regular and greater efficiency of food.


-Acquisition and processing


We can look at adaptations to both 1. Capturing and . Processing food


Modes of Feeding


-There has been a great diversification of mammalian adaptations to feeding (see Fig. 6.1) from the ancestral insectivores to highly specialized forms (e.g. Baleen whales)


We recognize several trophic groups


1. Insectivorous


. Carnivorous


. Herbivorous


4. Omnivorous


Plus other highly specialized forms


E.g. -Frugivorous


-Planktivorous


-Piscivorous


-Sangreinivorous


All of these come with adaptations of both the hard (mostly skull and teeth) and soft (mostly stomach and intestines) anatomy.


-See Fig. 6.1 and 6.


Insectivory (includes other arthropods and worms)


-Primitive, basal, or ancestral condition of eutherian mammals.


-Today exploited by 7 major groups


-Montremasta


-Insectivora


-Chrisoptera


-Xenarthra- anteaters, armadillos


-Pholidota- pangolins


-Tubulidentata- aardvarks


-Carnivora (the aardwolf)


The teeth are sharp, with sharp cones and blades for piercing, shearing, and crushing the chitinous exosheleton.


-Sometimes the incisors are modified for grasping


Digestive system tends to be short and lacks a cecum as is typical for high protein diets.


Not all insects are the same (e.g. a larger heavy “shelled” beetle vs. a moth) and therefore even among insectivores we can see a tremendous amount of diversity.


Aerial Insectivores


The Chiropterans (bats) typify this diversity.


-70% of micro chiropterans are insectivorous; however, there are often specializations within these bats.


Morphology- beetle eaters have more robust skulls and larger teeth.


Habitat/Niche- some glean, some forage in open area, some in dense forests.


-Of course, we can relate form and function


Many forms of terrestrial insectivores


-Platypus has venomous spine on rear legs.


-Platypus


-Order Insectivora (hedgehogs, shrews, indes)


-Shrews- of which are the only mammals with venomous saliva.


-Blarina brevicauda


-Neomys fodiens


-Solenodon sp.


-Why in shrews?


Use Blarina as an example.


-Must eat all the time


While originally believed the venom functioned in subdividing the prey, it is now believed its primary function is to paralyze the prey for storage (much the same as spider wasps).


-The shrew places paralyzed prey in a cache so that it has fresh food and more importantly, a predictable quick source of food.


Toxin comes from sub maxillary glands and is delivered through a groove in the lower incisors.


-Shrews eat things other than insects


Ant Specialists


Mymecophagous


-armadillo


-Echidnas


-Anteaters


-Pangolin (scaly anteaters, p. 5-)


-Aardvark


-Numbats (marsupial) p. 185)


Adaptations


-Tactile organs on nose (Fig. 6.4)


-Reduction of teeth.


-No teeth (echidnas, anteaters, pangolins)


-Peg-like teeth


- x lengths of head and anchoredate.


-Long extendible tongues (Fig. 6.)


-Long snouts


-Powerful forelimbs (for digging)


Many mammals other than Insectivora and Bats consume insects- some just when they are available, others as a regular part of their diet.


-E.g. aardwolf, bat-eared fox, grasshopper mouse (Onychomys), possums, even primates.


Carnivory


-Order Carnivora


-Marsupial Dasyuridae- includes the famous Tasmanian devil and extinct Thylacinidae (Tasmanian wolf).


Not all members of Carnivora are carnivorous (e.g. giant pandas eat bamboo shoots).


-Tremendous diversity, but most carnivores have strong, heavy skulls, jaws and teeth sharp incisors, large canines and within Carnivora the carnassials (last upper pre-molar and 1st lower molar) that are designed for shearing meat.


Typical Adaptation for carnivory include things other than jaws and teeth.


-Speed


-Claws


-Acute senses of hearing and smell, and often vision.


-Vision often binocular (with depth perception too)


-Social organization (packs, prides)


-Jaw musculature is fundamentally different (see Fig. 6.6)


Carnivorous bats


-5 families have carnivorous members


-False vampire consumes birds, bats, rodents and insects


-Famous grog eating bat (Trachops cirrhosus)


-At least species are piscivorous Bulldog or fisher bats (Noctilio leporinus) have long hind legs with gaff-like claws that they drag through the water.


-Capture fish up to 8cm long


- species are sanguinivorous all in family Phyllostomidae and New World Tropics and Sub-Tropics.


All consume exclusively blood and thus have similar adaptations (see p.88)


-Large knifelike incisors and canines


-Reduced molars


-Tongue functions as a straw with a pair of grooves. (See Fig. 6.7)


-Intestine designed to store blood and absorb HO.


-Forelimbs adapted not just for flight, but also terrestrial loco.


-Heat- sensitive pits around nose


-Anticoagulants in saliva.


-Kidneys are unique.


- phase renal function


1. Get rid of excess HO in order to fly- ~5% of ingested blood excreted as very dilute urine.


. Once back at the roost, digest partially dehydrated blood and excrete a highly conc. urine (similar to or surpassing desert mam.).


Piscivory


-Already mentioned the piscivorius bats


-Also seen in seals, sea lions, dolphins and toothed whales.


-Jaws and teeth of pinnipeds (see Fig. 6.8) (order Carnivora) are not typical carnivores- adapted for grasping fish and swallowing whole.


-Toothed whales (including dolphins and propoises Suborder Odontocetes) see p.7


-Order Cetacea (homodont dentition) have numerous, small simple teeth.


Planktivores


-Mysticeti cetaceans have baleen that they use to filter plankton and other small organisms (krill) from the water.


Herbivory


Primary consumers


-While plant food is more abundant, its energy content is lower and more difficult to obtain or extract due to the though cell walls and other fibrous material in plants.


Herbivores can be divided into groups


1. Browsers and grazers


. Gnawers


Adaptations


In General


-Canines reduced, lost, or modified for other uses


-Broad molars


-Long intestines with cecum


-Sometimes multichambered stomachs


Teeth usually high- crowned (hypsodont) with ridges (lophodont) or crescents (selenodont).


Jaw muscles are different because mastication is from side-to-side (Fig. 6.6)


-Maseter and pterygoideus are major muscles and jaw articulation is high and “lose”


-Incisors and tongue used to “clip” grass and leaves


Mammals lack cellulolytic enzymes


-Thus have symbiotic protists and bacteria to break down cellulose and young ungulates get them from soil.


Ungulates have different systems for breaking down cellulose


1. Foregut and Hindgut fermentation.


. Forget fermentation (Rumination)


Order Aetiodactyla


-Camels, giraffes, deer, cows


Also kangaroos and colobus monkeys!


-Multichambered stomach with microorganisms (See Fig. 6- and 6-)


-Rumen- 1st and largest


-Reticulum- nd chamber, where “cud” is formed “Cud” is regurgitated and chewed again.


-Food swallowed again and enters


-Omasum- rd chamber, muscular-walled.


-Abomasum- 4th is true stomach


Can have additional fermentation in the intestinal cecum.


. Hindgut fermentation


-Order Perissodactla- horses, zebras, rhinos, tapirs


-Also Orders Lagomorpha and Rodentia


Food moves rapidly from simple stomach to intestine- no requrg


-Small particles go to cecum


-Large particles pass as feces


Because hind-gut mammals pass food rapidly with minimal fiber digestion, some have evolved Coprophagy (feeding on feces).


-Rodents and Lagomorphs and shrews


Lagomorphs produce types of feces.


1. 1st are mucus-coated and black and promptly


. nd are hard, round, and passed normally


Among rodents, at least 4 families have internal or external cheek pouches- store and carry food.


Specialized forms of herbivory


Granivory- rodents, especially Heteromyidae


Folivory- 4 genera or 4% of mammals Eucalyptus- koalas, gorillas (86% leaves) sloths, pandas, and some deer.


Fruguvory- some bats, primates


Nectarivory- 6 genera of bats and honey possums


Gumivory- plant exudates resins, saps, gums.


-8 species of marmosets, mouse lemurs, gliders, 1 possum


Mycophagy- fungus- contain phosubets and many other nutrients- and spores pass through digestive system.


Omnivory


-Most mammals are omnivorous and very opportunistic


-Omnivory is best illustrated in opossums, primates, pigs, bears, and raccoons.


Cheekteeth are often bunodont, broad, and relatively flat of crushing food.


Foraging Strategies


-Optimal foraging- these models attempt to predict the combination of costs and benefits that will maximize fitness.


Energy and time are types of currencies considered.


-These in turn can be broken into foraging categories.


E.g. 1. Find or locate food


. Capture and subdue


. Process


Marginal Value Theory- when do you leave a “patch” for a new now?


-Distance, quality of food.


Food Hording or caching has been reported for 6 orders and 0 families of mammals (only! Marsupial)


1. Larder hoarding- all food in 1 place


. Scatter hoarding


Chapter 7- Nervous and Endocrine Systems


The nervous and endocrine systems are the major control and sensory systems in vertebrates (mammals included)


This is a short chapter- READ IT!


Vision


-Tapetum lucidum- reflective layer outside the retina that reflects light back to retina.


-Causes eye shine


-Cornea and dens are farther from retina in diurnal mammals (See Fig. 7.1)


-Rods (black/white) cones for color durinal have more cones.


Hearing


-With smell, the most important senses in mammals- WHY?


Mammals are unique in having external ears (pinnae) can hear form infrasound (0Hz) to ultrasound (0,000 KHz). -Ears also serve for balance.


Olfaction (Smell)


-Finding food and sensing environment.


-As already discussed, mammals have a variety of glands.


-In addition to the normal olfactory receptors in the nasal cavity, also have vomeronasal organ on the floor of nasal cavity.


Touch


-Hairs have pressure receptors


-Vibrissase


-Specialized “touch receptors” see fig. 6.4 “Eimer’s organs” on a moles.


Central Nervous System


-Most of the mayor difference between mammals and other verts are in brain morph.


-E.G., expansion of the cerebral hemispheres (meocortex) of the telencephalon.


-Other differences in brain morph. Associated with senses (e.g. rat has m ore olfactory cortex; others more visual).


-Increase in ratio of brain size to body size over mammalian evol. also surface area.


Endocrine System


-Hypothalomcis (part of midbrain) and Pituatary gland control this system.


-Hypo controls the pituitary which releases hormones.


Glands and Hormones


-Edocrine glands release hormones (lipids) steroid and protein types.


-Hormones control reproduction but also regulate metabolic processes (e.g. thyroid gland).


-Thyroid releases thyroxin which increases cell resp. which increases heat.


-Insulin glucagons system maintains homeostasis of carbs in blood.


-Pheromones are released because of hormone action.


Bio Rhythms


-Circannual- 1yr.


-Ultradian- 4hrs


-Circadian- 4hrs


-Diurnal


-Nocturnal


-Crepuscular


-Photoperiod sets the “clock”


-The timing or clock mechanism has major components.


1. Retina


. Thalmus- specifically intergeniculate nucleus


. Suprachiasmatic nucleus of the hypothalamus.


Remember, it was the hypothalamus that controlled the pituatory.


Pineal gland, which is important in reptiles and amphibs, does not appear to be a primary component, but it affects circadian rhythms via its secretion of melatonin.


Circannual


-Hibedrnatioin


-Estivation


-Breeding


-Also cued by photoperiod and sometimes temp rain, and food


Once again, the or 4 components mentioned above are important but the exact control mechanisms remain unknown.


Chapter 8 Environmental Adaptations


Terrestrial mammals experience a tremendous array of environmental extremes, How do they deal with this?


-We will start with temperature


-Endothermy- metabolic heat


-Ectothermy- heat from outside


-Homeothermy- the regulation of a constant body temp “by physiological means” not all authors agree


-Poikilothermy- often used in place of “ectothermy”


-Heterothermic- varying body temp daily, seasonally, or across the body.


Mammals have metabolic rates some 8x higher than that of ectotherms


-Tremendous energetic cost, but advantages include


1. Enhancing coordination of biochemical systems


. Increasing information processing


. Speeding central nervous systems functions


4. And this can more efficiently capture prey and escape predators


5. Gain relative independence form temp. extremes


Most mammals maintain a body temp. of 6-8 C (monotremes and marsupials are somewhat lower, 0- C)


Must maintain thermodynamic equilibrium


Mammals (and others) exchange heat with their environment (Fig. 8.1)


-Radiation, conduction, convection, evaporation


-Mammalian properties that influence this exchange are


1. Metabolic rate


. Evaporation (rate of moisture loss)


. Thermal conductance of fur and fat


4. Absorptivity of radiation


5. Body size, shape, and orientation


Temp. is monitored at the shin and hypothalamus.


Heat is generated by muscle contraction brown fat thyroid activity.


Adaptation to Cold


-Thermoneutral zone- range of environmental temps within which the metabolic rate is minimal (and doesn’t change much).


-Upper and lower limits of the thermoneutral zone


-Upper and lower critical temps.


Some mammals and birds are so well insulated that they can withstand the coldest temps on earth (-70 C)


But, in addition to raising met rates they must reduce heat loss.


HOW? -Body size and shape.


-Insulation (fur and fat)


-Changing peripheral blood flow


-Behavior


Upper Critical Temp- temp above which a mammal must use evaporative cooling.


1. Behavior


. Cooling mechanisms (pulmonary, sweating panting, etc.)


The key in cold and hot is to maintain an energy (and water in hot) balance! (See Fig. 8.4).


Mammals have evolved mechanisms of avoidance and resistance to cold. (Table 8.1)


Avoidance


-Body size and its relation to metabolic rate. (See fig. 8.5)


Some terms


-BMR basal (resting) metabolic rate vol of O consumed/timed at standard pressure and temp.


Total metabolic rate- absolute#


-Increases with body size


Mass- specific met rate �adjusted for body size (rate of O consumed per gram of body mass.


-Decreases with body size


Size and shape affects heat loss because of surface area volume ratio


Doesn’t always hold true


-WHY?-Will there are other evolutionary and ecological constraints


-Food (less in arctic)


-Use weasel example


-Mammals have insulation


Insulation


-Length is not the only important factor


-Length of fur and thickness of fat


-type and shape of fur


For aquative mammals longer fur is not practicle and fur loses its insulation properties in HO.


-Therefore they trap a layer of air under thin fur


Fat and “blubber”-thick layer of “white” fat.


Marine mammal fat is all blubber, they have no visceral fat.


But can overheat with blubber.


-Elephant seals- can shunt blood to the surface through arteriovenous anastomoses to cool the body.


Appendages (legs, tails, ears, nose) can lose heat.


-Reduce length (Ollen’s rule)


-Use a countercurrent exchange system


-Allow extremities to approach zero degrees Celsius (See fig. 8.)


Coloration


-Gloger’s rule- races in warm/humid areas are more heavily pigmented that cool and dry areas.


Many mammals change pelage color with the seasons in northern climates and others remain white all year (e.g. polar bear- actually their fur is hollow and clear)


Molt- is usually cued by photoperiod (decreasing/increasing day length) endocrine.


-Optic nerve-hypothalamus-hormones


-Also a genetic component


-Color may (but read text) offer to conceal prey and predators


-May convey a thermal advantage but color is far less important than other factors (e.g. length, structure color of skin etc.)


-E.g. polar bear- pigment less hair transmits 0% of UV sunlight to black skin and warms body.


Nesting and social behavior can be adaptations to cold.


-I will not cover this, but read it on pp17-0.


Reduction in Activity levels


-Dormancy- period of inactivity characterized by a reduced metabolic rate and lowering of BT


-Torpor- is a form of dormancy


-When this is used they are usually referring to a type of dormancy other than hibernation and estimation.


-And not as extreme


-In winter called hibernation


-Summer, estivation


-Daily torpor


In torpor, BT rarely declines below 15 degrees Celecius Daily torpor species include some rodents (including our Peromyscus) marsupials, insectivores, bats, and primates.


Hibernation- “profound dormancy” BT -5 degrees Celsius for weeks


-. degrees Celsius in arctic ground squirrels


True- hibernation is seen in ground squirrels, marmots, and hedgehogs


-the largest being marmots (Marmota)


“True hibernation” is not possible or necessary in larger mammals


Larger mammals (e.g. bears) go through a period of “mild” torpor known as winter lethargy, with a BT only 5-6 degrees Celsius lower than normal.


Also body size allows them to store more fat.


-WHY? - would take too to come out of true hibernation


Bats hibernate or migrate (they also exhibit dai8ly torpor)


-While they arouse every 1- weeks to urinate, drink, and change location if needed, arousal burns calories, and even though~1/ of their body mass might be fat, this can be fatal.


Talk briefly about bat conservation and “gates” on caves.


The greatest # of hibernators is Roberts- specifically squirrels (Sciuridae)


Marmots- BT --8 degrees Celsius


-Heart 100bpm- 15


-Oxygen- 1/10 the (Breath only every 6 min)


Hibernation mammals often follow a “Cycle of dormancy”


-Entrance dormancy, arousal See Fig 8.17 for Richardson’s ground squirrel


So for we have discussed only AVOIDANCE of cold.


Now let’s discuss RESISTANCE


-If avoidance fails, a mammal must resist cold by generation heat


-Muscle activity (voluntary involuntary)


-Increase metabolic rate


Many small mammals employ “nonshivering thermogensis” that does not involve muscles but rather brown adipose (fat) tissue


Brown fat in all hibernation mam.


-Brown fat seen in at least 7 orders all utherian.


-Also seen in newborns (e.g. humans)


-Brown fat, unlike white fat, contains many small (rather than 1 large) droplets of lipids (fats), is highly vascular, many mitochondria and is therefore capable of greater heat production (and O consumption).


-While white fat severs primarily as insulation and energy storage, brown fat serves as an active metabolic heater for the blood.


-In brown fat ATP is not produced but rather heat is the end product of cellular resp.


-Probably triggered by temp. and controlled by hypothalamus.


Adaptations to Heat (p. 16)


Desert mammals (or mammals in hot environs) must dissipate heat or avoid it.


Your book concentrates on deserts- so water balance also plays a key role


-Osmoregulation


Water Economy


Desert mam. Typically produce conc. Urine and dry feces.


-Most of the elimination of excess HO salts, urea, uric acid, creatinine, and sulfates occurs through kidneys


-Look at structure Fig. 8.1 and 8.0- Know basic kidney structure and function


-Nephrons are the functional units and consist of a glomerular capsule and a long coiled tube (includes the Loop of Henle)


-Renal corpuscle- the glomerular capsule plus the mass of capillaries (glomerulus)


Feces of Merrianms K-nat are .5x as dry as a lab rat and desert rodents produce urine conc. Of 000-6000mOsm/L.


-608 dog- 1675 pocket mouse.


Exchange of substances takes place through active transport and osmosis.


The concentrating ability of the kidneys (works through a counter current exchange system) is related to the length of the Loop of Henle and the collecting ducts in the medulla- therefore the relative size of the medulla tells us something about HO retention in the mammal RMT- relative medullary thickness.


The size and length of the renal papillae is also an indicator of HO retention and reabsorption abilities- desert mams have very long renal papillae.


In addition to conserving HO and some consume the dibute urine of their young.


Also, must recover HO through the respiratory system via a countercurrent exchange system in the nasal passages.


-Incoming air is moisturized


-Outgoing air comes into contact with the relatively cool walks of the nasal passages and water condenses out and is reabsorbed.


Desert mammals often do not have access to HO- therefore they must it from succulent plants, prey, or using metabolic water


Temp. Regulation


Evaporative cooling


Transpirational HO loss


-sweating


-panting


-saliva spreading


-respiratory heat exchange


Hypothalamus


Eccrine sweat glands used in response to overheating in primates, and some urgulates, (eg. Camel)


Panting- carnivores and smaller ungulates (sheep)


-panting has the advantage of being more controlled and of cooling the grain via the cavernous sinus


Saliva spreading- rodents, marsupials


Respiratory HO exchange (Fig. 8.)


Insulation


-fur can be used to minimize the heat absorbed


-hair is unequally distributed over the body, giving thermal windows to allow for heat loss


-even hours can be thermal windows


Appendages- we already discussed this


Metabolic rate- lower


Body size- already discussed


Dormancy- already discussed estivation- dry or hot seen in pocket mice and K-mice (See and read the Case study p. 144and the camel p.145-6)


Avoid high temps.


-burrows


-nocturnal


Become heterothermic (see Fig. 8.0 & 8.1) and (See also Fig. 8.)


Chapter Reproduction


All mammals reproduce sexually via internal fertilization (i.e., the sexes are separate-clioecious)


The major groups of living mammals show a broad array of reproductive traits


-Subclass Prototheria


Order Monotremata


-lay eggs (oviparous)


-have cloacae


-only left ovary functional (birds also)


-lack nipples


Subclass Theria


Infraclass Metatheria


-Marsupials


-viviparous


-have cloacae


-pouch (marsupium)


-nipples


-young born in an altricial state


Infraclass Eutheria


-viviparous


-highly developed placenta


-separate openings for reproductive and digestive systems


-precocial young


-nipples


Use Possum example- Not more advanced and primitive- just different.


Variation is tremendous


-gestation period ranges form 10 days (some marsupial) to 650 days (elephants)


-lactation varies from 4-00 days


-1-15 young


-from -4 weeks between births to -4 years!


Female system


-paired testes, paired glands, a duct system, and a copulatory organ


-gametogenesis (and specifically spermatogenesis) occurs in the tests via meiotic division the testes also produce testosterone


-in seminiferous tubules


-via leydig cells around the seminiferous tubules


-testes often in a pouch- like structure called a scrotum


-bats and rodents testes migrate between body cavity to scrotum during breeding season


-scrotum for cooling of testes


-sperm cannot be produced at high temps.


-monotremes, some insectivores, anteaters, tree sloths, armadillos, manatees, most seals, whales, and elephants the testes remain in abadomin


-in primates artiodactylids, perrisodactylids, and carnivores they remain in scrotum


-on leaving the seminiferous tubules, sperm are collected and sometimes stored in the epididymis


-sperm leave via the vas (ductus) deferens which travels to the urethra


glands add secretions to the seminal fluid near the juncture of the vas deferens and urethra


-seminal vesicles ()


-single prostate


-bulbourethral glands ()


“Cowper’s”


These and other glands nourish the sperm, act as a lubricant, and in some species form a copulatory plug, and protect the sperm from the acidic environment in the female urethra and female vagina


Copulatory organ- penis


-highly vascularized with corpora cavernosa- hollow bodies that fill with blood


-all carnivores most primates rodents, bats, and some insectivores


-the glans penis may included the as penis or baculum and shows may configurations eg. Bifurcate in monotremes and marsupials


-corkscrew in pigs


Penis may be anterior (most eutherians) or posterior (marsupials, and rabbits) to scrotum


Male system


-paired ovaries (produce ova and via oogenesis hormones- progesterone and estrogen)


-paired oviducts


-one or uteri with a cervix


-vagina


Ovary


-under the surface of the ovary are the follicles, each with a single ova


-At birth large #’s of follicles are present ( million in humans)


- types of steroid hormones are released from the follicles (see above)


The Estrous Cycle and Ovulation (fig..6 and .5)


-All nonprimate mammals (including some primates) experience a period of brief receptivity before and after ovulation- this is called estrus.


-The estrous cycle is hormonally controlled- SEE FIG. .6


In most mammals ovulation (follicle bursts, releasing the egg or ovum see Fig. .5) is spontaneous, but rabbits, many carnivores, some ground squirrels, some desert rodents and voles experience induced ovulation due to copulation or in the case of the desert rodents and montane voles- due to the content of green veg.


The time span form I period of estrus to the next is called the estrous cycle and may occur


-1 time per year- monstrous more than 1- polyestrous


The ova are discharged late in estrous during ovulations p.154


-development of the follicular cells is controlled by FSH- follicle-stimulating hormone and LH- lutienizing hormones produced by the anterior piluitary.


High levels of LH cause ovulation, and a mature follicle ruptures, then fills with follicular cells and is called the corpus buteum.


-can examine ovaries for presence of corpus butea.


The corpus luteum produces progesterone which triggers and promotes the growth of the edometrium and allows for implantation of the zygote and stimulates the mammary glands


LH binding cells are called theca cells which develop peripherally the follicles LH stimulates theca cells to produce testosterone which is converted enzymatically into estradiol.


Inactive corpora lutea become corpora albicans


The developing follicles, under the control of FSH, secrete estradiol and this also promotes the development and maintenance of the endometrium.


If sperm is present in the oviduct, fertilization may occur and the fertilized egg. (zygote) moves to the uterus for implantation.


-See diff. on p.157 and Fig. .


-Duplex


-Bipartite


-Bicornuate


-Simplex


Then gestation begins


-The blastocyst -64 cells implants in the endometrim and becomes a trophoblast and sinks into the vascularized endometrium


The placenta begins to form, first as villi


The Placenta


-both embryonic and maternal tissues


Performs several functions


1. anchors the fetus to the uterus


. transports nutrients to fetus


. excretes wastes of fetus to mother


4. produces hormones


The placenta (specifically the clorion) produces lymphocytes and proteins that black mom’s Immune response


Marsupials


-very reptilian


-choriovitelline placenta (.11A)


-yolk sac is enlarged


-weak link to mom


Eutherians


-chorioallantoic placenta (.11B)


-small yolk sac


-extensive, well developed placenta


Gestation and Parturition and Lactation pregnancy


See Fig. .15


Marsupials have a much shorter (relatively) gestation period and a much longer lactation period.


Gestation is correlated with body mass, # of young/litter, the degree of development of the young.


Reproductive Variations


Delayed Fertilization (or ovulation)


-Vespertilionidae and Ehnolophidae bats (in temperate zones)


-copulate before hibernation but ovulation is arrested


-some mate during hibernation


-fertilization (and ovulation) takes place in spring


Why delayed fertilization?


-don’t waste time and energy searching for mate in spring and this allows bats to be born earlier and thus the time to build energy reserves before hibernation.


Delayed Development


-fertilization takes place, but the implanted blastocyst develops very slowly


-seen in micro- and megachiripterans


-synchronizes birth with when food is available


Delayed Implantation


-in spotted skunles the bastocyst “floats freely” in uterus for ~6.5 months


-when environmental conditions become favorable, implantation takes place


-Obligate- armadillos


-Facultative- doesn’t always occur eg. Rodents and insectivores


In addition, seen in bears, mustelids, seals, bats, and roe deer.


Embyonic Diapause


-makes sense in harsh Autralians environment


-some kangaroos and other members of that family


-young kangaroo is born and enters pouch


-female mates again when the young is ~6 months


-the presence of the suckling young arrests the development of the new embryo for as long as 5 days (See Fig. .17)


-the second young is born after the 1st leaves the pouch


-suckling causes hypothalamus to not release FSH and LH


- young may be dependant on mom at same time


1. weaned joey (still suckling occasional


. pouched joey


. embryo


Parturiton


-controlled and mitiated by a variety of both fetal and maternal hormones


Altricial vs. Precocial Young


FETAL


-adrenocortical (cortisol)


initiates parturition


-placental estrogen increases


and estrogen increase


-placenta produces prostaglandins


cause uterine contractions


Maternal -pressure of fetus on cervix


stimulates production of


oxytocin


-relaxin (produced by corpora


lutea) softens ligaments of pelvis


Lactation- production of milk by mammary glands


-Ovarian hormones estradiol + progesterone cause enlargement of mammary glands


-following parturition, estradiol decreases which signals the pituitary to secrete the lactogenic hormone prolactin- this stimulates milk production


-suckling by the newborn stimulates the production or “letdown” of milk via the hypothalamus and pituitary, which releases oxytocin


Milk


-contains fats, proteins (especially casein), and lactose, vitamins, salts, and water


-also transmits passive immunity


-composition of milk varies greatly among mammals (see Table 5.1 on p. 68) and milk can change composition during the course of lactation


eg. Fat content varies from 0.g? in Black rhinos to 4.8 in harp seals


In general, mammals living in northern (cold) environs have extremely high fat, high protein milk.


-all male mammals except monotremes have nipples, but the arrangement and # varies


-marsupials generally have a circular arrangement of nipples # varies from 1-


-Eutherian mammals typically have nipples arranged in longitudinal ventral rows


Lactation ranges from 4 days in hooded seals to 00 days orangutans.


Chapter 0 (part 4)


Communication, aggression, and Spatial Relations


-The development and evolution of the neocortex of the brain is generally credited with giving mammals the ability to exhibit complex behavior and to learn.


Communication


-Displays are behavior patterns that convey messages


-Most mammals have only 0-40 displays


-A signal is the physical form of the message


Biological Communication


-see Wilson’s def. on p. 45


Properties of the signal


-discrete- either this or that


-graded- more variable


-distance


-duration


-composition


-syntax


-context


Modes of Communication


Table 0.1 “Sensory Channels”


Odor- pheromones


-priming= generalized response


-signaling= produce immediate motor response


Mate identification, attraction, territories, alarm, etc


Sound- much more information about immediate conditions can be transmitted faster by sound than by chemicals.


-the best frequency is usually determined or modified by the environment


-in general, high freq. (ultrasonic) are for shorter distances and low freq. (infrasonic) for long distance.


Sound travels farther and faster underwater


Can be used to communicate with conspecifics, hear predators, locate prey, sense environment.


Vision


Social and diurnal mammals rely heavily on visual cues


Touch


-in most primates and some other social mammals, touch and particularly grooming is very important.


Electric field


Platypus uses sensors on its bill to detect the electric field of prey (worms)


FUNCTIONS OF COMMUNICATION


-“All communication ultimately functions to increase fitness”


But what are the more immediate or proximate functions.


-Group spacing and coordination


-Recognition


-Giving and soliciting care


-Aggression and Social Status


-Soliciting play


-Soliciting


-Alarm


-Hunting


Aggression and Competition


Agonistic behavior is probably a better term and includes


-Aggression can be considered as a form of resource competition


-threats


-submissions


-chases


-combat


Does not include predation, but does include Infanticide and Sibleicide.


Competition


-exploitation


-interference


Spatial Relations


Home Range- where an animal spends most of its time


Core area- area within home range that gets heaviest use


Territory- a home range or core area that is defended


Lek (rare among mammals)-the only resource being defended is the mating space


Chapter 10 Monotremes and Marsupials


Class Mammalian


Subclass Prototheria


Order Monotremata


Family Ornithorhynchidae (1gen, 1sp)


Tachyglossidae (, )


-Both of Australia and nearby islands


Monotremes differ significantly from marsupials and eutherians in their retention of reptilian features (see fig. 10.)


-reptilian microchromosomes


-e.g. pectoral girdle, epipubic bones, and the reproductive morphology


-lay eggs, and thus have very nonmammalian reproductive tracts (fig, 10.1)


-only left ovary functional as in birds


-early cleavage stages in embryo are meroblastic (similar to reptiles and birds) and not holoblastic (mammals)


-young have and egg tooth (reptile and bird)


-young feed on milk, but female’s lack teats/nipples (they do have mammary glands which are identical in structure to those of marsupials)


-monotremes and marsupials lack a corpus callosum (connection between hemispheres of brain)


-fossil records indicate that monotremes have always been in Australia, however a platypus has been found in Argentina.


Ornithorhynchidae- monotypic


-Platypus (Ornithorhynchus anatinus) is semiaquatic and semifossorial inhabitant of freshwater streams, lakes and rivers along the east coast of Australia and in


Tasmania.


-feeds on inverts, small fish and amphibs


-Male’s ~50cm, Female’s smaller


-bill is soft, pliable, and highly innervated with tactile and electroreceptor


-the digits are in the ancestral condition 5 (pentadactyl)


-spur with venom gland (fig. 10.5)


-young have molars that are lost and replaced by keratinized pads


-build burrows in the banks where ~ young are born and nurse


Tachyglossidae- Echidnas (spiny anteaters) species


-Sort-beaked (Tachyglossus) occurs throughout Australia, New Guinea, and Tasmania


-Long-beaked (Zaglossus) is restricted to forested highlands of New Guinea


Both have a long rostrum and long tongue that they use along with sticky mucus to obtain food.


Tachyglossus- ants, termites, etc


Zaglossus- earthworms


-Male’s have non-functional spurs


-have a pouch


-the long-beaked (Zaglossus) is considered threatened


Subclass Theria


Infraclass Metatheria


-7 orders


-18 families


-~68 species


Largest families are Didelphidae (new World possums), Dasyuridae (marsupial mice and others) and the Macropodidae (kangaroos and relatives) in that order


While this clade is named for the marsupium or pouch not all marsupials have a pouch and the echidnas have one.


However, they differ form the eutherians in many ways (see table 10.1) and fig.10.7 and 10.8


-Female’s have a bifurcated reproductive tract and Male’s have a bifid penis (fig 10.1)


-Marsupials have a choriovitilline with no villi placenta rather than the chorioallantoic


-Scrotum is anterior to the penis in most


-Not all marsupials have a pouch


-numbat, some didelphids, rat-possums and many marsupial mice


-there is diversity in those that have pouches (see Fig 10.10)


Gestation is short (short fig 10.7) and the young are born @ 1g (see fig 10.11)


The young have muscular, clawed forelimbs that use to crawl to the pouch/nipples


Note


This short gestation time and this development of the forelimbs have been proposed as part of the reason marsupials has not been as diverse as placentals. Also, there are differences in relative grain size.


-forelimbs thus cannot become hooves, flippers or wings.


Living marsupials occur in N.A. central and S.A. and Australasia.


They probably arose in N.A. and we will talk about their Zoogeography later


Orders have been developed based on dentition and digits


-Didactylus- unfused toes


-syndactylous- nd and rd fused


Chapter 1


Dominance behavior, territoriality, etc are often related to mating and mating systems.


-I will not discus all topics in this chapter because many stray from the central topic- mammalogy


-I will illustrate or touch on several important points


-Anisogamy- female’s gametes are larger and require more energy to produce and therefore are likely to be a limited resource for which male’s compete.


-A male’s reproductive success is likely to be a function of how many female’s he can inseminate, whereas a male’s success depends on the # of eggs and young she can produce.


-Whereas most mammals (animals) have a 5050 sex ratio at birth, this can change to produce the operational sex ratio of adults.


-Female’s in good condition should produce the best offspring


-Male’s in good condition should provide good genes and maybe the right resources for the females


(p.60) Dominant red deer hinds have access to the best feeding sites and thus produce the healthiest offspring


-Male’s compete intensely to control harems


-A female that produces a large, healthy, successful son can achieve more than twice the reproductive success of a male producing a daughter. (see fig. 1.)


-Female’s in poor condition produce daughters.


Sexual Selection


-Many traits seen in mammals are sexually selected traits resulting in sexual dimorphism.


What does the large antlers of a moose tell the female?


How does all of this affect the mammal’s life history?


Parental Care


Itreoparity vs. semelparity (very rare) - one genus- the marsupial mouse


Parent- Offspring Conflict


Mating Systems


-tied to the distribution and abundance of resources (see fig. 1.1)


-polygzny- males mates with multiple females


-polyandry- 1female and more than 1male


-rare African wild dog


-polygamy


-monogamy (mostly in primates, carnivore, and rodents)


-promiscuous


Chapter - Social Behavior


Most mammalian social systems are organized matrilineally


-group composed of mothers, daughter’s sisters, aunts, nieces, grandma.


Complex social organization has evolved in nearly all mammalian orders (probably why they have a large brain?), but especially in Carnivora, Cetaceans, and Primates.


Examples of Cooperative Social Behavior


-alarm calls


-cooperative rearing of young


-coalitions and alliances


-eusociality (naked mole rat)


-as seen in social irrsects such as bees


Costs and Benefits of living in Groups


Costs


-Intraspecific Competition


-Disease and Parasites


-Interference with Reprod.


Benefits Protection form Environment


-Intraspecific Competition for Predators


-Disease and Parasites finding and obtaining food


-Defense of resources


-Locating mates


-Division of labor


-Learning


Evolution of social Behavior


Group Selection, Kin Selection


Altruism- Reciprocal Altruism


Inclusive fitness- success of offspring and success of relative’s offspring


Blood sharing in vampire bats


-most between mothers and offspring


-others were close relatives and “associates”


Wilkinson- 184


Nature- 08 181-4


Wilkinson- 10- Sci. Am. 6 64-70


Environment (Ecology) also affects social behavior.


E.g. one condition that might favor helping parents raise other offspring is a stable, predictable environment. Unoccupied territories are absent or rare.


But can also be explained in harsh, unpredictable environ.


Marsupials (cont.)


Didelphimorphia (Ameridelphia) 15 genera + 6 species, all in one family Didelphidae Range from Canada to southern S.A. (only 1 north of Mexico, Didelphis virginiaina)


-pentadactyly


-ancestral dental formula


-Body mass form 10g-Kg


-most have sparsely haired, prehensile tails, and opposable thumb


-the most generalized and ancestral metathericans


-occur in almost every habitat


-most are omnivorous


-most are terrestrial, although some are semi arboreal


-the most specialized didelphid is the yapok, or water opossum (chironectes minimies), the only habitat, with webbed feet


Virginia Opossum (Didelphis virginiana) is the only marsupial in N.A. and Mo.


-TL 4-4in, Weight 4-15 lbs (1.6-6.8Kg) males larger.


Easy to identify the skull and pelvis (has epipubic bones)


-ears and naked, tail with scales


-front feet with 5 toes, back with 5 I5/4 C1/1 P/ M4/4= 50 more than any other mammal in Mo


-Females have pouch


-males have a forked penis and scrotum anterior to penis


Short-lived, maybe 5yrs, pop. Turnover~every yrs.


The opossum has extended its range


E.g. before 117 the opossum did not live north of Illinois or west of Kansas


Likes wooded areas near fields/open areas and streams


Does will with humans


-prefers animal matter, but will eat almost anything


-In Mo breeding begins in Feb with a gestation period of 1-1 days, 5-1 (x=) young are born in late Feb. and weaned by May


-1 teats in pouch lactation ~60 days


Females mate again and the second loiter weaned in Sept.


Young 1/ inch long


In 10’s average number of pelts sold in Mo were 88,44 with a high of 46,11 in 140


Dasyuromorphia families living, 16 genera, 6 sp.


-small to medium sized


-Australian


-most in family Dasyuridae marsupial “mice” or “shrews”


-also includes larger extenct Tasmanian wolf and the Tasmanian devil (the largest living carnivorous marsupial)


-several species have carnassial molan


-includes the numbat which is an ant specialist


-includes the smallest marsupials


Diprotadontia-10fam. 116 species.


-primarily herbivorous but, some are insectivores, nectivores, etc.


-kangaroos, koala, wombats and others


-most terrestrial, some arboreal


-all are diprotodont (1st pair lower incisors enlarged to meet upper, shortened mandible.


-nd and rd digits syndactylus


-In arboreal species (e.g. koala) the 1st digits oppose the other making them schizodactylus- forefeet


-upper canines present but variable


Phascolarctifae- monotypic- koala


Phascolarctos cinereus


-occur in Eualyptus woodlands in E and SE Australia


-with a body mass of 6.5-1.5kg (males larger), they are among the largest arboreal browels


Eucalyptus is not easy to eat and digest; therefore Koalas have the largest cecum relative to body size of any mammal- (see Chapter 6).


-must consume large amounts (~500gld)


-Hindgut micro flora are thought to detoxify some of the oils- liver plays a role.


-the koala ahs a chorioallantoic placenta, but with no villi


Macropodidae- 11genera and 50sp. Makes it the rd largest family


-body mass ranges form 1kg wallabies to the 80kg red kangaroo (Macropus rufus)


-browsers and grazers


-most are terrestrial, some are arboreal


-their ecology and morphology parallel eutherian artiodactyls.


Their digestive system is similar to the multichambered system of ruminants


-they even regurgitate food for additional chewing


-the skull is even similar, with a large diastema and incisors used to clip veg.


-the molars are hypsodont (high-crowned) and serially replaced from the rear, similar to elephants. Only seen in this family.


-saltatorial locomotion with the large (“macro”) hind feet and long strong tail (see Fig. 10.6)


-A single young is produced and embryonic diapauses occurs in all but 1 species


Chapter Dispersal, Habitat Selection, Migration


We must distinguish between more local movements, e.g. within or near the home range (including natal dispersal), and large-scale dispersal such as migration.


Philopatry vs. Dispersal


Why disperse?


-avoidance of inbreeding


-reduce intraspecific competition


Males most commonly disperse in mammals


“Dispersal in lions follows the typical mammalian pattern”


Female’s stay, male’s leave (usually before 4) Males leave pride before their daughters start mating.


This is the typical pattern, but in some mammals (e.g. banner- tailed K-rats, pikas, and chimps, males disperse. (Very rare).


Habitat Selection and Use


-just because they live there doesn’t make it the “optimal” habitat (and in fact it may be sub-optimal- talk about metapops).


-Why not occupy “optimal” habitat?


-competition


-predation (see Fig. .4)


-genetics


-learning


-life history


-climatic variables


Migration- persistant movement across different habitats in response to seasonal changes in resource availability and quality.


While it is triggered by proximal cues (photoperiod, hormones, etc.) it is ultimately tied to resources.


Some bats migrate


e.g. hoary bats and free-tailed bats


Most species of baleen whales


(Mysticeti) migrate


-summer at high latitudes


-winter in warmer water to breed


This migration is for breeding, not for food resources


Pinnipeds migrate to island breeding sites that are relatively free from predators, sometimes great distances.


Large ungulates are probably the best- know terrestrial migrators


-caribou- winter summer


-wildebeests- wet/dry seasons


-elephants


How do they migrate? Home?


-they just “know” or learn the route


-landmarks, smells sun compass magnetic compass (whales, some rodents and maybe even humans?


Chapter 5 Community Ecology


The Ecological niche- an organism’s place AND functional role in a community; the total of adaptations of a species to a particular environment.


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