Mammal diversity and evolution - Week 21 Flashcards
What are the 3 mammal groupings?
- Monotremata (prototheria)
- Marsupialia (metatheria)
- Placentailia (Eutheria)
What are some general mammal characteristics?
- Backbone, insulated with fur, nurse with milk, unique jaw articulation
- Teeth replaced once or never, prismatic enamel on teeth
What are the sections of the mammary glands?
- Mammae = mammary glands = Milk production (these are modified sweat glands)
- Mammillae = nipple/ teat = milk delivery
What are mammals unique jaw articulation?
- Dentary meets squamosal bone in skull
- AKA, lower jaw only has one bone
Who evolved first, mammals or birds?
Mammals, 160 mya, amniote ancestor with reptiles
Where did first mammal-like features first appear?
300 mya, subclass synapsid - Limbs carried below body, enables rapid locomotion,
What were the first mammal niches?
- Insectivorous, nocturnal
Monotremes characteristics?
- Retain reptilian features, lay in brood egg, single discharge hole (cloaca), infants lap milk from mammary glands
- Platypus, has venom from gene duplication
Theria characteristics?
Similar tooth patterns to marsupials
What occurred with marsupial adaptive radiation?
- Evolved in pangaea, then move to north America, then spread all over
- Once isolated, underwent considerable adaptive radiation
- Many marsupials went extinct once they started co-living with eutherians
Name some examples of ecological equivalents?
- Sugar glider, independently evolved gliding behaviour
- Tasmanian devil, many marsupial equivilants
- Spotted hyenia, many marsupial equivalents
How does Marsupial reproduction differ from Eutherian?
- Have placenta, but only loose contact with foetus
- Shorted gestation
- New borns poorly developed but can crawl , can be integrated during lactation
What do you know about the opossum genome?
- Advanced immune system, inherited building blocks from common ancestor
- Most genetic innovations from regulatory DNA, and other non coding elements
The placentalia + Euthierians make up what?
Infraclass placentalia
What are the 4 superorders of placetital?
- Afrotheria, elephants/ manatees
breast cancer gene, trunk fused upper lip/ nose - Xenerthra
pilose = ant eaters
Cingulata = armadilos
teeth reduced, claws on toes - Laurasiatheria
- Euarchontoglires
How was pangae to the modern-day continents important?
- Cruital for evolutionary radiation/ specialisation
What are the classes of small mammals?
- Lagomorpha, rodentia, eulipotyphia
What are some key features of Eulipotyphia?
- Noctournal, poor vision, good sense, small smooth brain, many teeth, cloaca, no scrotum
- Shrew, emit ultra sonic clicks (crude echolocation)
- Hedgehodgs/ moonrats, heterothermic
What is the cost of being small?
High SA to volumw ratio
Have to eat own many everyday
High speed respiration
What are some key features of lagomorphs?
- Distinguished from rodents by peg teeth
- Coprophagy
- Prolific breeders
What are some key features of rodentia?
- simple teeth, big balls, social structure, have working caste
- Workers and breeders, kin selection
- Eurociality! Colonial
What are the two orders of Ungulata?
How are they distunguied?
- Perissodactyla, axis of foot 3rd toe, odd
- Rhino, horses, tapirs
- Artiodactyla, axis of foot 4th toe, even
- Pig, deer, camels
What do Artiodactyla contain?
- The Ruminants, able to digest cellulose!
- Deer and bovids
- True deer have antlers!
What are deers roar and horns for?
To attract females and scare males
