Lesson 23: Diversity of Animals Flashcards
what is the largest extant mammal and the largest extant terresterial
blue whale/elephant
therians vs. non therians
eutherians
- placental mammals
metatherians
- marsupeals
the nontherian mammals are these monotremes
DIFFERENCES
- thereians are viviperous
- monotroemes lack nipples
- lumbas ribs are lost in the therian
- have a skeleton that is related to bounding behavior
– involved the evolution of the scapular sling
– all this internal viscera is suspended between the scapula and long muscles
—- helps with shock absorber when you’re bouncing through the grass
- therians have a calcaneal heal
– attachment of achillies tendon
– gives the foot a lot of leverage
- some skull differences
- the shape of the nasal bones being flared vs rectangular (eitheria)
- on average the marsupials differ in the dental formula
- some skull differences
- the shape of the nasal bones being flared vs rectangular (eitheria)
- on average the marsupials differ in the dental formula
diversity of marsupials
- themetatherians actually got originated in asia (we think)
- and then they dispersed to north america in the early cenozoic
- thought to have dispered to australia separated from antartica
- both groups have dog-like, catlike, flying squirrel0like, fasorial herbivores, and digging ant eaters –>examples of convergent evolution
^^^ do not have common ancestor
^^^ their ancestors underwent similar environemental pressures
african originating ungulates
- from the provosciea
- elephants
- there is evidence of the elephant’s kidney that suggest a faily recent quatic ancestor CONCULUDING that elephants were secondarily terresterial
** the first terresterials were aquatic
boroeutheria
- carnivores refer to not only a diet but also to a taxa
- not equivalent
- pangolin is the world’s most poached animal despite having the most protection
viviparity is universal for eutherians as a whole + sexual
- thought to evolve once
- places a big physical change to the mother
- change in the immune system so that they don’t reject their young
- reduced pressure having been descended
- sexual preference of testes being descented
- scrotum is posterior to the penis in most placentals
- metatherians have a cloaca
- process of placentation
process of placentation
- key amniotic membranes
- form different structures that get different kinds of structures names
- correoalentic placenta
ex: kangaroo
- presence of transient appearance of a shell (in marsupeals)
- don’t think of marsupeals as being transiety – it is a pretty derived group
- often enege with well developed lungs and forelimbs, but an underdeveloped neural system
- the motehr kangaroo will not assist the young kangaroo – it has to get out of the birth canal then travel into the pouch (might provide a litmus test)
- in that she hasn’t really invested in her young yet – continue to caring or stop caring and start again
- kangaroos – one of the rare vertebrates that have sibling offsrping that are simulataneously dependent at different stages –> similar to birds and incubation
tusks can develop out of different teeth
- show sex differences
- probably a sexually selected for trait
- rodents are known for gnawing 00 undergo a huge amount of tooth repair
lophodontia
- sharm bladed enamel regions separated by dentene
–> hipsodontia
very large temporalis in carnivores
- not in herbivores, but herbivores have a very strong masseter
- masseter muscles are good at chewing –> narrow gape
- carnivores do a lot of wider gape
only cellulose enzymes can digest cellulose
- plant cell wall
- no known vertebrae that can digest it
- form a asymbiotic reltionship with bacteria
plants and energy
- plants have a lot of energy content per gram compared to meat
- then energy that is available is hard to access
- possible that hindgut digestion is the ancestral trait
hindgut digestion
PROBLEM
– the energy is made accessible to the organism in the hindgut, after it passed through the foregut (absoprtion)
- hindgut fermenters – fractures cell wall – increases surface ara
cow stomach
- gets protein from bacteria
- ^^ cows digest bacteria
- if you have a ton of forge of diffreent types – a hindgut fermenter can digest them very quickly
rabbits
- hindgut fermenters
- eat their own poo for nutrients
- with the elevated surface area to volume raitio – foregut fermenter takes too long – has to be hinggut
hindgut
do with better quality
foregut
starve if low quality but high in quality
morphologies
corsorial limb morphology
- maximizes speed at the expense of power
- tend to be long for coveing distanc e
- musculature restricted to proximal regions – makes the distal regions quite light
HORSE
- most of leg musculature is concentrated close to central body
- restricted to movement in a single plain
forsorial limb morphology
- refers to digging
- maximizes power at the expense of speed
altricial
- monotreme
- marsupial
- eutherian
precocial
eutherian cow
- not fully independant but shortly after birth it is on its legs and thermoregulating
large mammals
- produce less offspring but their young lives longer compared to smaller mammals
large carnivores
- tend to have multiple large altricial young
- while large herbivores tend to produce few precocial young, herbivores would have to face predation so it is better for them to be independent when born
more efficient for carnivores to have altricial young
- the rush to develop wastes energy
- they have the luxury of slowing things down
- thermoregulation is incredibly expensive
naked mole rats
eusocial
– there is a queen
– very genetically related
spotted hyena
pseudopenia
– female clitorus develops much like a male penis
- females develop under high androgen levels
— very masularized as a result
— they make all the decisions in the group
fully aquatic mammals
pinepeds come out of the water very often
- spend a lot of time on the peach
- can exist outside the water for certain amount of times
seals and thses other things are still called fully aquatic (species like beavers are semi)
- 3 evolutionary events for aquatic mammals
– blubber instead of haor
^^^^ need blubber to be fully aquatic
