Mammology Exam Study Guide PDF

KNOW GRAPHICS FROM POWER POINTS L1 - Intro to Mammals 1. About how many living species of mammals have been described? - 6600 species in 30 orders 2. Draw a mammalian hair, with important associated structures (glands, nerves, muscles). What is the most important funct...

KNOW GRAPHICS FROM POWER POINTS L1 - Intro to Mammals 1. About how many living species of mammals have been described? - 6600 species in 30 orders 2. Draw a mammalian hair, with important associated structures (glands, nerves, muscles). What is the most important function of mammal hair? - Insulation is most important: high density of hair (pelage, fur coat) serves to trap thin layer of air above integument - this prevents heat dissipation from body to the environment (retention) 3. What are secondary functions? Fur coloration - Concealment: conceal yourself - Thermoregulation: reflect light - Intraspecific or Interspecific communication: communication (warning) Imparting Color: Hair color can provide camouflage, helping animals blend into their environment and avoid predators. For instance, the white fur of Arctic mammals like polar bears and Arctic foxes allows them to blend into snowy landscapes. Hair color can also be used for signaling, such as in mating displays or warning coloration to deter predators (e.g., skunks). 2. Sensory Structures: Specialized hairs, like whiskers (vibrissae), serve as important sensory organs. These hairs are deeply embedded in the skin and connected to nerve endings, allowing mammals to detect nearby objects, movement, and textures. This is particularly useful for nocturnal or burrowing species like cats or rodents, who rely on tactile feedback. 3. Protection: In some species, hair is modified for protection. Examples include the quills of porcupines and hedgehogs, which are stiffened, sharp hairs that protect them from predators. These quills act as both a deterrent and a defense mechanism. 4. Communication: Some mammals use their hair to communicate. For example, animals may raise their fur or “puff up” to appear larger and more intimidating when threatened (e.g., a cat’s fur standing on end). Similarly, some species 4. Some mammals are nearly hairless – give an example, and explain why the loss of hair is expected in this case. - Loss of hair is an adaptation to their - Beluga whale is nearly hairless or Hippo - whale has a different type of insulation (fat vs fur) due to environment (being in the water) - hippo and elephant lives in tropical habitat so they shouldn’t have a lot of fur, and they are very big. 5. Lactation is expensive - give an example. What are the three primary components of mammal milk? - Milk is composed of fat, crude protein, and lactose and other sugars which varies across all mammals - An example is that humans require a 50% increase in dietary energy used in order to produce milk 6. What does the conservation of certain milk proteins tell you about the evolution of lactation? - Striking conservation in certain milk proteins across VERY distant relatives, reflects conservation in function - even though mutation is always happening it never changes due to natural election - there is high percent identities due to important functions - the conservation of milk proteins shows that lactation is an ancient, critical adaptation that has evolved to provide both nutritional and immune support to offspring. This underscores the importance of lactation in the evolutionary success of mammals. 7. What are three benefits of endothermy? - can be active under a wide array of temperatures, including extreme — cold habitats - freed from dependency of day light- dark and seasonal cycles —- many mammals are nocturnal active through all seasons - endothermic BMR is 10x than ectotherm (Body metabolic rate) - endothermic can sustain aerobic activity far longer (foraging, avoiding predators, etc) 8. What are costs of endothermy, and why are these costs size & temperature dependent? - mammals expend 5/10X more energy to maintain Tb (body temp) than an ectotherm of equal size and equal body temp - energetic cost is temperature dependent (more extreme at lower temps) - energy cost is also size dependent ( in small mammals 80/90% of total energy budget is spent on maintaining high Tb ( small mammals are constantly eating) - Small-bodied animals have a higher surface area-to-volume ratio, meaning they lose heat more quickly to the environment. As a result, they must produce more heat per unit of body mass to maintain their internal temperature. This makes endothermy particularly expensive for smaller animals, as their metabolic rates are proportionally higher. 9. Mammals are a prime example of adaptive radiation – give examples? - Mammals are indeed a prime example of adaptive radiation, the process by which organisms rapidly diversify into new forms and ecological niches following changes in their environment or the evolution of new traits. - An example would be bats since they are the only mammals that capable of true fly  - aquatic mammals such as dolphins which is a significant departure from their ancestors 10. How are camera traps being used in modern mammalogy? - Useful for elusive mammals, in difficult weather/terrain, can gather long-term data - - Gathering data regarding species diversity, species abundance, behavior, range sizes, etc. - 11. Define: mammal, hair cortex, lactation, endothermic, homeothermic Mammal: living mammals are hairy, lactate, endothermic, amniotic that mostly give live birth (there are exceptions such are prototherians) Endothermic: have a body temperature principally dependent on internally generated metabolic heat homeothermic – maintain relatively constant internal body temperature (Tb) regardless of ambient temperature (Ta) hair cortex - The Hair shaft is multi-layered (inner medulla, middle cortex, outer cuticle) => cortex cells rich in keratin proteins, + pigments which impart coloration Phylogeny Assignment 1. placental root placements have been supported by data – draw an unrooted tree that shows these. 2. Give an example of morphological convergence in mammals, and discuss the significance of this convergence – what does convergence tell you about the evolutionary process? - anteaters and numbats both have sticky tongues due to similar diets and way to acquire food - shows how different lineages can acquire similar traits due to similar selective pressure regardless of different environment 3. Be able to draw a phylogeny that shows paraphyletic, polyphyletic, and monophyletic groups. 4. Draw “PTME” relationships, be able to place all Placental orders into their correct Superorder (polytomies are fine), with correct interrelationships of the Superorders (Springer et al molecules tree), from memory (i.e., ordinal names NOT provided). - laurasiatheria is a super order and Carnivora is an order - so we won’t be given a word bank of the names?  - For the quiz Relationships among orders within superorders can be left unresolved., but for the exam do we have to. Define: lineage, anagenesis, cladogenesis cladogenesis : when a lineage splits Lineage: This is where individuals are tied together by ongoing genetic exchange, they all contain a common ancestor anagenesis is an evolutionary process in which a single species gradually evolves into a new species over time without branching into separate lineages. In anagenesis, the ancestral species undergoes enough genetic changes and adaptations that, over many generations, it becomes distinct enough to be considered a new species. However, the original species doesn’t coexist with the new one; it is effectively replaced by its evolved form. L2 - Mammal Origins 1. Draw a graphic of deep time that shows 3 Eras (with dividing times), in correct order from past to present. 2. What is the function of the temporal opening in an early synapsid? - Modern Mammals part of Synapsid lineage => single temporal opening between postorbital & squamosal bones - Function of temporal opening => attachment point, allowing expansion of jaw musculature 3. Draw the four primary synapsid lineages correctly on a phylogeny. 4. What is the functional importance of a secondary palate? - Allows animal to breath while chewing food - with later importance in suckling 5. Discuss the importance of the End-Permian Mass Extinction (EPME) event. - which occurred around 252 million years ago (Ma), was the most severe extinction event in Earth’s history, marking a pivotal moment in the evolution of life.  - resulted in the extinction of approximately 80-96% of marine animal species and 70% of terrestrial vertebrate species - Largest decline in global biodiversity in past 500 Myr - radically altering Earth's ecosystems and reshaping the evolutionary trajectory of life. The most widely accepted cause of the EPME is the Siberian Traps volcanic eruptions, - Massive CO2 emissions: The volcanic activity released enormous amounts of carbon dioxide (CO2) into the atmosphere, leading to severe global warming. - Ocean Acidification: The increased CO2 dissolved in the oceans, lowering the pH and disrupting marine ecosystems, especially affecting calcifying organisms like corals and shellfish. - Acid Rain: The release of sulfur dioxide (SO2) and other gases likely led to acid rain, further damaging terrestrial and aquatic habitats. Cyodonts which are derived from theraspids Survived EPME, diversified extensively in Triassic. These animals gave rise to mammals surviving synapsids like cynodonts were able to persist in smaller roles and gradually evolve into more diverse forms, eventually leading to the evolution of true mammals. - synapsids were no longer the dominant land vertebrates after EPME Without the resilience of certain synapsid groups, mammals—and ultimately humans—would not have evolved. This event highlights how mass extinctions, while devastating, can set the stage for new evolutionary opportunities and lineages to thrive. 6. What is a defining jaw feature of crown Mammalia? - lower jaw comprised only of dentary bone, jaw articulation = dentary-squamosal 7. What is the evidence for endothermy in Mesozoic mammals – be as specific as possible? Castorocauda with fur, many other extinct crown Mammals with fur => presence of fur ancestral for crown Mammals - was likely an ancestral trait for crown mammals.  Authors infer that other biological functions of integument (thermal insulation, tactile function) evolved BEFORE origin of crown Mammalia (early Mammaliaforms) - This indicates that early mammaliaforms were likely evolving towards endothermy, using fur for heat retention, much like modern mammals. Evidence for endothermy in Mesozoic mammals primarily comes from fossil records, including findings that indicate the presence of fur, which is closely linked to the ability to regulate body temperature internally (endothermy) Fossils like Castorocauda, a mammal form from the Middle Jurassic (~164 Ma), show clear impressions of fur. Since fur is typically associated with thermal insulation, its presence strongly suggests that these animals were endothermic, as they would need fur to retain body heat. Define: synapsid, heterodont, crown group, Mammaliaform Crown group: A crown group refers to the most recent common ancestor of a group of living organisms (extant species) and all of its descendants, both living and extinct. adaptive radiation: can adapt to many environments (lots of adaptations to different environments. synapsid lineage: single temporal opening between post orbital and squamosal bones (, which allowed for attachment of jaw muscles and facilitated stronger bites) - synapsid lineage: single temporal opening between post orbital and squamosal bones - there is an enlargement is temporal opening, movement of jaw muscles origins to above braincase and zygomatic arch - Some of muscles from lower jaw go to braincase and ZA Heterodont: mammaliaformes: subclade of Cynodontia – originating at ~ Triassic / Jurassic boundary (~ 200-210 Ma) – many changes in skeletal anatomy (and presumably soft anatomy) leading to mammalian ground plan: - in lower jaw there is gradual enlargement of tooth bearing dentary / reduction of post dentary bones - Dentition becomes strongly heterodont - Skeletal changes consistent with more efficient food-processing Heterodont refers to a type of dentition in which an organism has teeth of different shapes and sizes L3 Be able to answer the following general questions: 1. What are the three alternative models for timing of Placental mammal diversification?  Explosive model : Extinction of non-avian dinosaurs at Cretaceous-Paleogene (K-Pg) extinction event allowed radiation of Placentals - Most of the diversification happened rapidly after the extinction. Long fuse model: This model proposes that the origins of major placental mammal groups began during the Late Cretaceous( before the extinction ) but their diversification into the wide variety of modern species occurred after the K-Pg extinction. The "long fuse" refers to a gradual evolution and slow radiation, with diversification peaking after the extinction event. - the diversification into modern species occurred gradually and did not fully "explode" until after the K-Pg event. short fuse model : short fuse model suggests that placental mammals diversified well before the K-Pg extinction. 2. Which hypothesis is supported by recent data? Long fuse model - "relaxed molecular clock" methods applied in the study, as noted on the right of the image, use genetic data and fossil constraints to more accurately estimate divergence times. - This approach provides a timeline for placental mammal evolution that aligns with the Long Fuse Model The diagram shows that many major groups (represented by horizontal bars) diverged either before or shortly after the K-Pg boundary. For instance, lineages such as Afrotheria, Euarchontoglires, and Laurasiatheria have divergence points extending back into the Late Cretaceous (80–100 million years ago), supporting the idea of gradual diversification that started before the mass extinction. The graph in the lower half (D) shows speciation and extinction rates over time. It indicates some changes, but not a sharp increase at the K-Pg boundary, which again supports the Long Fuse Model where diversification was already underway and continued gradually after the K-Pg event, rather than exploding all at once. 3. How did the KTR have a biotic impact on early Placental diversification? The KTR saw the rapid expansion of flowering plants (angiosperms), which brought about new ecological niches and food resources. - produced fruits and seeds, creating new feeding opportunities for early mammals, including placentals Hyperdiverse insect lineages, such as Lepidoptera (moths and butterflies), Hymenoptera (bees, wasps, ants), and Coleoptera (beetles), co-radiated with angiosperms as their primary pollinators. - led to an increase in insect populations, providing early placental mammals with a new and abundant source of insect prey. - leading to the gradual adaptive radiation of placental mammals.  The widespread appearance of angiosperms and their associated pollinators during the KTR created a new ecological landscape. 4. Which abiotic factors were also impacting early Placental diversification? Old continental isolation also plays important role in radiation initial separation of Pangaea into northern continents (Laurasia) & southern continents (Gondwana) As the supercontinent Pangaea broke apart during the Late Cretaceous (~100 Ma) and into the Paleogene, placental mammals were distributed across increasingly isolated landmasses. This geographic isolation due to drifting continents led to vicariance, where populations became separated by physical barriers, such as oceans, mountains, or deserts, promoting the evolution of distinct mammalian clades. As continents drifted apart, early mammals isolated on different landmasses underwent speciation, leading to the formation of distinct groups such as Afrotheria in Africa and Xenarthra in South America. the diverse range of marsupials found in Australia and New Guinea is a result of millions of years of isolation from other continents, leading to a unique evolutionary trajectory. 5. Draw a global map with the six terrestrial zoogeographic regions. Why is there so much mammal endemicity in the Afrotropical region? significant geographic isolation - These natural barriers have limited the movement of mammal populations and facilitated the development of distinct species.  6. Discuss (maybe use a drawing) the biogeographic history of the Tenrecidae (*learning subfamily names not necessary). Tenrecs are a diverse group of small to medium-sized mammals primarily found in Madagascar, Tenrecs are believed to have originated in mainland Africa as part of the Afrotheria clade, Madagascar separated from Africa about 160 million years ago, long before the evolution of tenrecs. Tenrecs likely reached Madagascar by rafting or other means of oceanic dispersal, possibly around 40-50 million years ago. - Once tenrecs arrived in Madagascar, they underwent adaptive radiation, a process by which a single ancestral species evolves into a variety of forms adapted to different ecological niches. Africa (Afrotherian Ancestor): Tenrecs evolved as part of the Afrotherian group in mainland Africa. Dispersal to Madagascar: Around 40-50 million years ago, tenrecs dispersed to Madagascar via overwater rafting. Radiation in Madagascar: Upon arriving, tenrecs diversified into numerous species in Madagascar, filling various ecological roles. Continued Isolation: Madagascar’s isolation from mainland Africa allowed tenrecs to evolve independently, leading to high endemism.  The Tenrecidae lineage is not as old as Madagascar itself, which means tenrecs likely arrived after this split. The long-term geographic isolation of Madagascar played a key role in the high endemism of tenrecs. They did not face competition from placental mammals that evolved in other regions The 2 possibilities are by walking or waif, and waif makes the most sense 7. What does a chronogram for ALL Malagasy mammal radiations tell us about Malagasy biogeographic history? The chronogram for Malagasy mammal radiations illustrates that different mammal lineages colonized Madagascar at different times, predominantly from Africa through waif dispersal. The direction of dispersal was one-way from Africa to Madagascar, and there were no native mammals on Madagascar prior to these events. Once they arrived, these lineages diversified into the unique species we see today due to the island's isolation and unique environmental conditions. - Waif dispersal is a form of accidental, long-distance dispersal, where organisms—typically small animals or plants—are transported across bodies of water or other significant barriers. 8. How does marsupial evolution relate to plate tectonics? The Marsupials originated in Gondwana particularly in South America. - When South America, Antarctica, and Australia were still connected as part of the supercontinent Gondwana - then dispersed to other parts of Gondwana, including Antarctica and Australia. marsupials migrated or dispersed from South America to Australia through Antarctica before these landmasses separated. There were marsupials in Antarctica when it was still a part of Gondwana Antarctica drifted southward, it became isolated and its climate became much colder, eventually becoming covered in ice. This is why no extant (living) mammals exist in Antarctica today. Once Australia separated from Antarctica (around 30–40 million years ago), it became geographically isolated - With no new species coming into Australia, the marsupials there evolved independently from those on other continents - this shows adaptive radiation  9. Discuss the historical connections between the Palearctic and Nearctic – e.g., directionality and timing of biogeographic connections? palearctic: including North Africa, all of Europe and Asia The Bering Land Bridge (also known as Beringia) was a land connection between Siberia in northeastern Asia and Alaska in northwestern North America. Palearctic and Nearctic were connected by the Bering Land Bridge during the Cenozoic era This bridge enabled species to move between what is now Siberia (Palearctic) and Alaska (Nearctic). The timing of these biogeographic connections occurred mainly during glacial periods throughout the Cenozoic speceies moved in both directions across the land bridge Carnivores like wolves (genus Canis) and bears (genus Ursus) are found in both the Nearctic and Palearctic. Rodents such as squirrels and voles, and ungulates (hoofed mammals) like deer, are found in both regions due to these historic connections. 10. How does big cat phylogeny illustrate Holarctic biogeographic dynamics? Holarctic biogeographic dynamics refers to the movement, distribution, and evolutionary history of species across the Holarctic region, which includes the northern continents of both the Old World (Palearctic, which covers Eurasia and northern Africa) and the New World (Nearctic, which is North America). Big cats (genus Panthera) likely originated in the Palearctic (Eurasia) and radiated to other regions, including the Nearctic (North America), Africa, and southern Asia, over tim Some big cats, such as the American lion (Panthera atrox), dispersed from the Palearctic to the Nearctic during the Pleistocene epoch, using the Bering Land Bridge as a corridor. moved between the northern continents of the Old World (Palearctic) and the New World (Nearctic). Big cats likely have North Asian ancestry Define: chronogram, Cretaceous Terrestrial Revolution (KTR), Laurasia, Gondwana, biogeography chronogram: A chronogram is a type of evolutionary tree that explicitly incorporates time into its structure.  Laurasia: Laurasia was one of the two supercontinents formed after the breakup of the larger supercontinent Pangaea during the late Mesozoic Era - It comprised most of the landmasses that now make up the Northern Hemisphere ( North America, Europe and Asia) Gondwana: It formed the southern part of the ancient supercontinent Pangaea before Pangaea split into two major landmasses: Laurasia in the north and Gondwana in the south. - makes up the modern hemisphere KTR: refer to question 3 - The availability of these new resources helped spur the early radiation of mammals - the KTR was a period of rapid biological innovation that reshaped terrestrial ecosystems and contributed to the diversification of many animal groups, including early mammals. biogeography: studies the geographical distribution of plants and animals. https://quizlet.com/726940116/mammalogy-exam-1-study-guide-questions-flash-cards/ Lecture 4 Be able to answer the following general questions: 1. Why is it inaccurate to say that “monotremes are 200 million years old”? Monotremes do share a common ancestor with therians , but this ancestor lived much earlier, approximately 200 Ma ago. Crown-group monotremes date to around 40 Ma. - the most recent common ancestors of all living monotremes and their descendants - Therefore, modern monotremes are not 200 million years old; they are part of a lineage that evolved much more recently. 2. Fossils suggest what kind of biogeographic history for Monotremes? Monotremes, which include modern species like the platypus and echidnas, are believed to have originated from a common ancestor shared with therians  The discovery of fossils like Monotrematum sudamericanum in Patagonia (dating to the Paleocene epoch) suggests that monotremes had a broader distribution across the ancient supercontinent Gondwana (containing South America). Obdurodon dicksoni: This species is from the Miocene epoch, specifically known from fossils found in Australia. It is significant because it resembles the modern platypus the fossil evidence indicates that monotremes had a widespread distribution in Gondwana before becoming isolated in Australia and New Guinea, 3. How do “Ameridelphs” differ from Australidelphs? Which group forms a clade? Ameridelphs have a dual calcaneum astragalus joint, where Australidelphs have a single calcaneum astragalus joint surface -- Australidelphs form a clade where Ameridelphs are paraphyletic. 4. Describe the marsupial placental morphological convergence. Marsupials and placentals have undergone adaptive radiation  In regions like Australia, marsupials evolved in relative isolation from placental mammals. This geographical separation allowed marsupials to exploit various ecological niches without direct competition from placentals. ecomorphological convergence refers to the phenomenon where different species evolve similar morphological features to adapt to similar ecological roles or environments, despite being phylogenetically distinct - convergence of marsupials and placentals due to ecological roles or environments This convergence demonstrates that morphology often reflects ecological roles - both groups developed similar physical adaptations to thrive in comparable habitats. , the idea of replicate adaptive radiation in geographic isolation suggests that when different species are placed in similar ecological conditions but are separated geographically, they can evolve in similar ways to fill similar ecological roles. This leads to convergent evolution in their morphology, resulting in similar physical traits among unrelated species that occupy comparable ecomorphological spaces. 5. Describe the morphology and significance of the fossil siren Pezosiren. Time: From mid-Eocene (~ 50 MA) Transitional morphology: foot bones consistent with digitigrade (walking) posture, strong pelvic girdle => could support weight on land, Dorsal nasal openings, heavy ribs for ballast (*osteosclerotic) Importance: suggest much time spent in water (semi-aquatic). 6. Why is the FULL biogeographic history of Proboscidea relevant to interpreting modern-day diversity? Proboscidea (the order that includes modern elephants and their extinct relatives) Proboscidea originated in Africa, which serves as a critical point for tracing the evolutionary history and adaptations of these animals. Proboscidea participated in multiple beringian dispersals to different continents, leading to a wider distribution of species, including the woolly mammoth and mastodon. The biogeographic history illustrates how Proboscidea once occupied a broad range of habitats worldwide (excluding Australia). By examining this past distribution, scientists can assess how historical climate changes, geographic barriers, and human activities have shaped the current distribution of modern elephants and their relatives. it reveals how past extinction events, dispersal patterns, and ecological adaptations have shaped the current distribution and characteristics of living elephants. 7. Pangolins, armadillos, and aardvarks are morphologically similar – why? They share fossorial robust skeletons, reduced/no dentition, and are both ant and termite eating. These shared characteristics are due to an ecomorphological convergence -- they were evolving in similar environments at different parts of the world. Define: Riversleigh World Heritage area, osteosclerotic osteosclerotic: hardening of bone substance Riversleigh World Heritage area: Most famous Australia fossil site with rich carbonate rocks w/ Oligocene ( 30 Ma) to Pleistocene Austrelidelphs - fossils of Austrelidelphs are found in carbonate rocks