Mammalogy Final Exam

Biogeography

Study of the patterns of distribution of organisms (extant and extincta)

2 branches of biogeography

ecological zoogeography and Historical biogeography

Ecological zoogeography

- deals with relationships between mammals and environments (any time thinking about environmental impact on animal distribution)
- endemism, island biogeography, convergent evolution, latitudinal gradients (higher latitude, lower species diversity; lower latitude, higher species diversity --> closer to the equatior, productivity increases, higher competition with more species - increased specialization) (doesn't always hold)

Historical biogeography

- attempts to explain, by reconstruction, the sequence of events involved in the origin, dispersal and extinction of organisms (what historical events influenced distribution)
- alfred wallace was the 1st
- two main mechanisms: dispersal and vicariance

dispersal

originate, then disperse

movement of individuals on small (one lifetime) or grand (geologic time) scale

disjunct populations explained by stating that individuals dispersed across inhospitable habitat to colonize new areas, the barrier was always there

occurs from a center of origin

hard to test, unlikely, doesn't happen often

how to determine center of origin

oldest fossils of group, oldest fossils of nearest relatives, area with highest diversity

dispersal routes are great for faunal interchanges:

1. corridor. no resistance - beringia
2. filter route. only few species can make it. island hopping across central american land bridge before full formation
3. sweepstakes route. swimming, flying, rafting- big payoff but low odds. hoary bat to hawaii

vicariance

widespread species has been divided (think pangea/ continental drift)

(more testable) test first

new barriers can arise - big population can be split by some historical event

Became popular after plate tectonics

vicariance species pump

repeated pattern of isolation, speciation, etc.

Example:
- original population (a) in same habitat
- as habitat moves up, population splits with geography
- isolation cause split --> a and b
- as more ideal habitat occurs, they continue to move up (never leaving talus slope) --> becomes abc
- How can we test? Look at plants for a comparative analysis
- fossils, molecular, compare to other organisms

Faunal regions depend on ___ and ____

geography (location and connectivity with other regions) and major ecosystems (biomes) found in each area

endemism

unique to area (example is kangaroos in australia)

the more isolated, the more endemism

zoogeographic regions

- done by simpson
- different animals in regions
- arctic = north
- palearctic is the old world an has fewest endemics
- wallaces line between oriental and australian
- australian has 28 families, 12 endemics
-nearctic is new world
- neotropical has 52 families, 17 endemics

zoogeographic regions

Who is responsible for island biogeography?

Macarther and wilson

- studied polynesian birds
- smaller islands lacks in species richness --> depends on distance to mainland

David steadman

- excavated fire pits from the people on these islands
- at bottom of pit, found larger birds
- as reaching top, bones got smaller - start finding reptiles
- at top, dogs that they brought with
- colonization of people on islands could have driven lots of birds to extinction
- less species on smaller islands could be bc more places to hide

Island Biogeography factors

distance and size

Island biogeography (different sizes, same distance)

- bigger has higher species richness because richer habitat diversity and bc of how they get to the islands from the mainland --> more likely to hit bigger land

- smaller island, smaller population (higher extinction rate, lower colonization rate)

Island biogeography (same size, different distance)

-closer island has higher richness and higher colonization rate

extinction rate is roughly the same

SLOSS

- single large or several small dilemma

Which is more optimal? larger size or smaller

larger

Which is more optimal? 1 large protected area or multiple areas

single large

Which is more optimal? rounder area or oval area

rounder

Which is more optimal? closer proximity to other islands or further proximity

closer

Which is more optimal? connected areas or non connected areas

connected

Which is more optimal? buffer zone around area or no buffer zone

buffer zone

Adaptations (giraffe, zebra, camel)

Giraffe: eating habits probably not enough to balance the expense of having a long neck so neck length probably selected for necking

zebra: stripes thought to be for blending in, making them look bigger, camo from predators but that is not so. They are for avoiding blood sucking flies.

camels: toes, hump, etc. from cold, barren sub tundra environment --> works for desert conditions

paedomorphy

adult with juvenile characteristics

axolotl paedomorphy

gills on outside

heterochrony (different time) in heteromyidae rodents:

- skull measurements throughout development
- noticed differences in heteromyidae rodents that are in same clade and closely related
- allometric growth
- selecting for slowed development for something (hypermorphosis --> pocket gopher matures longer, develops faster, neoteny --> kang rat, progenesis --> kang mouse)

allometric growth

"different growth"
as grows, rest of body grows quicker than hind legs

how to be paedomorphic:

1.) slow development mature at same age (neotony)
2.) pushed sexual maturity earlier (progenesis)
3.) increase % development beyond ancestor = hypermorphosis

adaptation

modification of an organism that makes it more fit for existence under the conditions of its environment: a heritable physical or behavioral trait that serves a specific function and improves an organism's fitness or survival

exaptation

adaptation that's been taken over for a different use --> using for a different purpose than what it was adapted for

examples: hair --> originally for touch but exaptated for insulation, camo, etc.

spandrel

byproduct of another decision in design, rather than adaptations

Hyena Masculinized genetalia

Why?
- not to make birth or mating easier... mating, almost rolls back genitalia, birth is difficult

competition-aggression hypothesis

competition-aggression hypothesis

- social rank is clearly the variable influencing female reproductive success --> improved nutrition among high-ranking females

- spotted hyenas are only ones that are cursorial predators

- probably arose relatively recently

- other hyenas are scavengers, don't hunt on groups --> scarce resources which limits group sizes and overall population densities
- communal hunting to increase available food sources but increases competition after the kill especially among juveniles. Cubs of high ranking females have a big advantage (any mutation that increased female size and aggression would be advantageous --> 1st chance at food and offspring get 1st chance too, simple mutation leads to increased placental androgen --> exposed to androgen in placenta)

- selection for adult aggressiveness favored fetal androgen exposure --> secondary effect of producing male-like genitalia --> genital displays and meeting ceremony arose later

Unanswered question: why are males so non aggressive despite polygynous mating system?

Fitness benefits:
- high ranking female at weening is round head bc it gets prime cuts from mom, while low ranking female when weened has more sagittal crest for strong muscles so that it can survive

deserts/ hest physiological challenges

heat stress, water stress, cold stress (heat radiating into space at night)

cold stress thermal neutral zone heat stress

body can function without hypothalamus triggering to control cold/heat (resting metabolic state)

Ways of avoiding heat stress:

sweating (evaporative cooling), avoid heat, thermal inertia, urination, countercurrent heat exchange

Sweating (evaporative cooling)

arid animals don't sweat bc it's expensive and doesn't work; have to drink constantly to work. but still lose water through skin or paws

Avoid heat

nocturnal
- when diurnal animals reach arid/dry areas, they can switch to crepuscular (dusk/dawn)
- shift in activity

burrows, stick houses, shelters
- expensive to build
- passed on through generations

behavior
- jackrabbit ears, heat dissipation and thermoregulation

seasonal diet shift
- wet and dry seasons (more food that provides water in dry season)

estivation
- kind of torpor
- doesn't last as long as hibernation
- takes place in hot/dry seasons
- lower metabolism but not as much as in hibernation

thermal inertia

example: camels are functionally heterothermic mammals
- body temp changes everyday
-at night, sit to let heat radiate off
- when sun rises, they heat up continuously throughout the day

high fluctuations in body temp without water, with water it decreases fluctuations
- same thing happens with food, just takes longer once fed again

Urination

filter out nitrogenous waste
- extracts water from urine; aka concentrates urine
- camels can drink salt water due to concentrations urine enough to get rid of salt

Conserve water in arid environments:

mate in optimal season
-mother loses water when lactating --> rich milk

Countercurrent heat exchange

- cools blood moving to brain
- rete system
- cavernous sinus

for places with cold and warm environments, to face the cold but be able to transition to warm, you....

want to lower the lct

how to lower lct

insulation
- hair
- dense wool hair --> hallow medulla for air movements
- blubber
- cannot just shed blubber when moving so extra set of capillaries allow blood to the outside of blubber which lets heat out

countercurrent heat exchange
- vein and artery is side-by-side so that the heart is pouring over to cool blood

behavior
- curl up/decrease SA:V
- social thermoregulation --> huddling, spooning, etc. (decrease SA)
- Seek shelter
- basking - heliotherms

Avoid cold

different foraging zone, migration, dormancy, hibernationdf

different foraging zone

example: subnivean zone --> meadow voles
- snow on top of grass that allows voles to live freely without predators

dormancy(torpor)

-durations of short period of time (body temp dec 10 º - 20º)
- lots of rodents, small marsupials, bats, small insectivoresd

dormancy (hibernation)

- long periods of time (body temp drops near ambient)
- tough
- arctic ground squirrel
- spend between 8-10 months of the year
- soil temp can get down to -18º c, have gotten body temp down to -3º
- little brown bats
- up to 6 months or so, some migrate instead
- woodchuck (marmota mormax) largest hibernator in america

problems with hibernation

- waking up is expensive --> door mouse waking up costs 10 days
- grizzly bear doesn't truly hibernate because costs 11 million calories to manage dropping body temp
- protect the brain ---> mechanisms to do so like reducing protein translation

hibernation - non-shivering thermogenesis

brown fat
- vascular
- alot of mitochondria and thermogenin
- sops respiration from making ATP --> just released as heat

humans have brown fat...
- a lot in babies
- high metabolic people have brown fat, others short in brown fat

creatine

precursor for proteins

bear "hibernation"

urea --> creatine --> proteins --> urea

make own water and recycle it and pea ^
2 breaths/minute, drops temp to 6º

fight cold

activity, shivering thermogenesis, and ramp up metabolism

activity and shivering thermogenesis are temporary fixes, the other two are permanent

osmotic regulation(marine environments)

blood vessel carries in solute and liquids, these move through and are less salty at first but as the water begins osmosing out, gets saltier. the loop of henley (gradient) is the key to osmotic regulation (longer = better concentrating), then goes through the countercurrent gradient of salts and towards the top is in active transport with low salt value and by the end, the concentration grows

ability to concentrate urine may be a spandrel

why could urine concentration be a spandrel?

lobed kidneys of these creatures probably evolved in response to large body size and diving abilities and not the the challenge posed by a marine environment

from diving or large size

problems with diving

diving reflex

- pressure:
- the bends, oxygen toxicity, narcosis, high pressure, o2 supply

the bends - decompression sickness

every 10 meters adds on 1 atmosphere of pressure

- gases in solution (blood): increased levels of nitrogen in blood; when come out of water, air bubbles try to go back to air supply --> makes blood fizz

why don't whales and pinnipeds get bends?

recently found that they might

- can exhale before deep dive
- as diving, the pressure compresses lungs more leaving with basically no gas in the lungs

oxygen toxicity

o2 under pressure can become toxic, unsure how they deal with this

narcosis

nitrogen under pressure

same effects as laughing gas

initial exhale probably helpful for whales

oxygen supply - how they deal?

store oxygen

blood stream:
- 2x as many rbc
- lots of hemoglobin
- can store 2x o2 as us

but this doesn't cut it...

black meat:
- muscle tissue high in hemoglobin and myoglobin (hemoglobin in muscles)

this still doesn't cut it...

dive reflex
- circulatory changes:
1.) body cardia (slow heart)
- 160 bpm to 20 bpm while diving
- vasoconstriction
- happens quickly; while blood vessels constrict keeping blood pressure the same, less blood flow

fruit bat - diurnal

modified echolocation; clickingb

bat morphology for echolocation

nasal cavity distance correlates with frequency --> some bats make sound from nasal : nasal length is 1/2 of wavelength

ultrasound

above human hearing (> 20 KHz)

ultrasound: properties of increased frequency

1. better for small objects (insects)
2. fade fast --> allows for less echoes of objects. far away/ filters out environment
3. easily focused --> easier to aim; clean echo
4. rare in nature
5. bats 8-215 KHz --> correlation with size
cetaceans 20 - 30 KHz

amplitude

loudness

amplitude...

1. myotis -110 decibels/pulse REALLY LOUD
- dogs live differently than us with being able to hear such high frequency
how don't they destroy their ears?:
2. tensor tympanum
tighter eardrum when sound pulse emits
3. tensor stapedium --> tenses stapes
4. auditory bullae floats in cartilage --> kind of soundproofs it
5. amplitude reflects environment
- deep forest animal; quiet voice/low amplitude call
- animals in the open; a lot louder calls b/c larger areas to scan

harmonics

gives bat distance, shape, texture

example: 80 120 240 (multiples of 40)

FM

frequency modification

CF

constant frequency

Fm continued

a lot of bats do both
- changing how fm does allows for understanding of physical property of objects like size and shape

directionality

differential intensity --> louder is closer

differential timing --> which ear comes to first tells direction

need to know speed and direction of movement to catch moving prey... how? (echolocation)

doppler shift (uses CF)
train example
- shifts up if something is moving towards
- shifts down if moving away from you

distance is a time lag, how long it takes for sound to return

repetition rate phases

1. searching pulse
| | | | |
- longer, more spaced out

2. pursuit phase
| | | | | | | |
- looking for more info

3. capture/kill phase/ feeding buzz
|||||||||||||||||
- needs max info to guarantee catching prey

cetaceans use dentary to receive info, jaw dent slightly to help with directionality but not as sophisticated as bats

Insect natural selection response to bats

- many steep dive to try to get away from bat, most insects are hearing bats not seeing them
- some have big timpana on outside to pick up soundwaves from bats
- selection for doppler "scrambler" strategy
- cloaking device by vibrating wings super fast
- ex: vibrating genitals to make sonar sounds

genetic tree puts dolphins with bats

genes used for echolocation
- same mutations
- convergent evolution at gene level

pitcher plant evolved ___

acoustic reflectors to attract bats: bats sleep protected, pitcher plant gets nitrogenous food from poop

phylogenetic tree

xenarthra examples

anteater, armadillos, sloths

afrosoricida example

tenrecs

sirenia example

manateep

proboscidea example

elephants

hyracoidea example

hyrax

tubilidentata example

aardvark

macroscelidea example

elephant shrew

primate example

chimpanzee

dermoptera example

colugo

scandentia example

tree shrew

lagomorpha example

rabbit

rodentia example

rat

eulipotyphla example

molec

chiroptera example

bats

pholidota example

pangolin

carnivora example

tiger

perissodactyla example

zebra

cetartiodactyla example

orca

theria example

cat

eutheria example

placentals - capybara