020614I. The Science of ClassificationII. Working principles for constructing a phylogenyIII. The challenge of reconstructing mammalian phylogeniesHomeothermy and temperature regulationBasic skeletal anatomyStructures associated with homeothermy (*diagnostic)Dentition and feedingI. Teeth related to homothermy, because need to take in lots of fuel.BSCI334: Exam I012814Defining mammals- Characteristics true of mammals but also other kinds of organisms: o Live birth (not a characteristic of all mammals)o Endothermic- warm blooded or make their own heat (birds, maybe dinosaurs)o Four chambered heart (crocodile, birds)o Homeostasiso Single dentary boneo Three ossicles in the middle earo Enucleate erythrocyteso Muscular diaphragm- Diagnostic characteristics of mammals: o Lactation (mammal comes from mammary gland) all sexes of mammals have the glands because main difference between males and females is hormonal environment. Male fruit bats are known to lactate, not sure if natural of a result of environmental hormonal contamination. o All mammals have hair.- Mammals make up a small percentage of all living organisms and contribute relatively little to the biodiversity of the planet Why we should care about mammals- Context: We are mammals too. By understanding mammals, we understand more about ourselves and what it means to be human, including our evolutionary history. We have similar physiological, behavioral, social, and ecological traits. - Practical reasons: we use them as food, work, protection, medicines (venom in horses to produce anti-venom from horse’s immune system, so large that it is more like a bee-sting to them) rabbits and goats also used for antibody research (pregnancy test used to be based on rabbits immune response to hormones produces by pregnant women “the rabbit died”), disease vectors (rabies, HIV, swine flu, the plague, mad cow, lime disease, Ebola, SARS). All mammals carry some kind of disease that can be transmitted to humans. Pests: animals that compete with us for our resources. - Ecology/conservation: mammals are often times keystone species that the ecosystem revolves around. If population decline, it can cause a cascade of problems. Ex: wolves and coyotes used to hunt deer, now that we’ve removed them as predators there is a larger population of deer. Use large animal species with widespread popular appeal to achieve environmentalist goals charismatic mega fauna - Scientific reasons: important for clinical researchClassification schemes1. Aristotle: mammals were viviparous animals with red blood. “reality is notable through direct experience”a. Recognized three categoriesi. Viviparous quadrupeds (give birth to live young)1. Ruminants with cutting teeth in lower jaw only which cloven hoofs (sheep)2. Solid hoofed animals (horses)3. othersii. Cetaceans (whales and their relatives)iii. Humansb. Problems: excludes a lot of things that we know understand to be mammals, like bats. Lacks monotremes2. John Ray: priest from Great Britain “knowing natural world brought you closer to god.” Father to natural history. a. Recognized group of animals with the following. Excludes other viviparous animals like fish. Good combination of characteristics, although no one is diagnostic for mammals. In combination, excludes all things that aren’t mammals, but also excludes monotremes (egg laying). First to define a species as a groupof organisms that can interbreed.i. Bloodii. Breathe with lungsiii. 2 ventricles in heartiv. Viviparous3. Carl Linnaeus a. Early editions defined mammals by:i. Hairy bodiesii. Quadrupediii. Viviparous1iv. Females made milkb. 10th edition: “Mammalia,” Linnaeus basically adopts Ray’s definitionc. Linnaean system: binomial nomenclature i. A hierarchical system: Seven obligate categories of classification. Basis for modern taxonomy of living animals. Considered species to be fixed, discrete, individually created entities. 1. Kingdom, Phylum, Class (mammals), Order, Family, Genus, Species2. Can also have intermediate categories (modifiers): “super-“, [category], “sub-“, “infra-“ii. A taxon can refer to any category of classification, means “thing”. Interpreted based on context.d. Nomenclature: system is used world-wide, avoids confusion i. Latinized wordsii. Name usually means something (carnivore = flesh eaters)iii. Endings often depend on level ……4. 1799: attempted classification based on locomotiona. Plantigradeflatfooted, ex: humans b. Digitigradewalk on toes, ex: dogsc. Unguligradewalk on toenails, ex: horsed. Problem with this type of classifications is that it groups together species based on appearance which can often be a result of living in the same habitat, and not necessarily common ancestry 5. Early 1800s Monotremes/Marsupials/Placentals. By the late 1800’s, these became known by the present day terms: a. Prototheriaearly-beastb. Metatheriasort-of-beastc. Eutheriatrue-beast6. George Gaylord Simpson: paleontologist. Important because considered living animals together with extinct animals (living species are only small fraction of animals) he brought in fossil record to classify. Three very distinct subclasses a. Monotremesb. Marsupials (young tiny compared to adult, short gestation period, very undeveloped young)c. Placentals (better developed young, longer gestation period)d. CLASS mammaliai. SUBCLASS prototheria (monotremes : very unique and long isolatied from other branches, lay eggs. Early offshootii. SUBCLASS allotheria (extinct multituberculates: among the earliest mammas known, fossils spana longer time than any other group) around for 100my very widely distributediii. SUBCLASS theria1. Ingraclass trituberculata (extinct: common ancestry to marsupials and placentals)2. INFRACLASS metatheria (Marsupials)3. INFRACLASS eutheria (placentals)LIVING ORDERSOrder Facts SpeciesMonotremata Echidna, platypusInfraclass metatheria(Formerly marsupial) fetuses attach themselves to female’s nipple, often staying in pouch until big enough to detach Kangaroo, Marsupial mole, Koala, Sugar gliderEutherian Well-developed placenta, give birth to live young Armadillo, Giant anteaterPholidota Covered with scales, made of keratin PangolinTubulidentata Aardvark only member of orderInsectivora Moles, hedgehogs, shrewsMacroscelidea Elephant shrewScandentia Tree shrewsDermoptera Flying lemurChiroptera One of two groups of bats, larger, plainer faces, smaller ears