Biology 1114H Exam 3

tetrapod

animal with four limbs

three major lineages of living tetrapods

1. amphibians
2. mammals
3. reptiles

amphibia

semi-terrestrial, complete metamorphosis, external fertilization,

examples of amphibia

frogs, salamanders, caecilians

causes of rapid decline of amphibia over last 30 years

chytrid fungus, habitat loss, climate change, pollution

amphibian life cycle

metamorphosis

paedomorphosis in amphibia

the axolotl reproduces sexually while still in "larval" form

paedomorphosis

retains larval or juvenile traits into later life stages

amniotes

synapomorphy of amniotic egg

amniotic egg

egg with protective covering that reduces the rate of drying

examples of amniotes

reptiles (including birds) and egg-laying mammals

Three inner membranes of amniotic egg surround

the embryo, the yolk provided by the mother, and the waste from the embryo

amnion

membrane that surrounds the embryo

yolk sac

membrane that surrounds yolk provided by mother

allantois

membrane that surrounds embryonic waste

albumen

egg white, cushions developing embryo and provides nutrients

membranes provide ____ and increase ____

mechanical support and surface area for gas exchange

three major lineages of mammals alive today

1. egg-laying monotremes
2. pouch-bearing marsupials
3. placental (eutherians)

eutherians

produce placenta within uterus or oviduct during pregnancy

characteristics of mammals

hair/fur maid of keratin, mammary glands, endotherm (warm blooded), 4-chambered heart

monotremes

egg-laying mammals, have hair, produce milk, lack nipples

examples of monotremes

platypus and echidnas

marsupials

live young born early that develop in marsupium, nipples provide milk, placenta provides nutrients in utero

examples of marsupials

opossums, kangaroos, koalas

placental mammals

eutherians, complete embyronic development attached to placenta

placenta

organ combining maternal and embryonic tissues

viviparity

development of young inside

evolutionary advantages of viviparity and placenta

1. offspring develop at more constant temperature
2. Offspring are protected
3. Offspring are portable (mother is not tied to nest)

Evolutionary disadvantages of viviparity and placenta

placenta is energetically expensive to produce and bearing live young is energetically costly

reptile skin

waterproof, keratinized

Four major lineages of reptiles

1. lizards and snakes
2. turtles
3. crocodiles and alligators
4. birds

reptilian adaptations for life on land

- skin is watertight by a layer of scales made of keratin
- breathe air through well-developed lungs
- lay shelled, amniotic eggs
- most are ectotherms (cold-blooded)

Wings and flight developed independently in these three lineages

1. pterosaurs
2. birds
3. bats

Vertebrate flights is a _____ trait

analogous

similarities between crocodiles, birds, and dinosaurs

four-chambered heart (possibly: brood care and vocalization)

Aves (birds)

endothermy, feathers, bill (keratin), flight, gizzard (instead of teeth)

characteristics unique to aves (not seen in dinosaurs)

- acute vision
- large brains
- ultra-light bones
- forelimbs modified as wings
- no teeth (minus some birds)

characteristics shared between aves and some/all dinosaurs

- feathers
- bill made of keratin
- bipedal
- endotherm

defining characteristics of primates

- hands and feet efficient at grasping
- opposable thumbs
- flattened nails instead of claws
- relatively large brains
- color vision
- complex social behavior
- extensive parental care of offspring
- forward-facing eyes

Hominids

(great apes) large bodied with long arms, short legs, and no tail, distinct ways of walking (fist-walk or knuckle-walk)

synapomorphy defining hominins

bipedalism

humans

large brain capable of complex tasks, upright, bipedal, reduced jawbones and jaw muscles, relatively short digestive tract

human/chimp genome comaprison

99% identical, differ in expression of 19 regulatory genes

population

all the individuals of one species in a given area at a given time

community

all the species in a given area at a given time

ecosystem

all the biotic (multiple communities) and abiotic factors and their interactions in a given area at a given time (includes energy flow and nutrient cycling)

biosphere

the thin zone of life surrounding earth

energy and nutrient flows link

abiotic and biotic components of an ecosystem

environmental compartments

- water
- soil and rock
- sediment
- air

anthropocene

major human impacts on ecology

primary production

- synthesis of organic compounds from atmospheric or aqueous carbon dioxide
- amount of light energy converted to energy in bonds of organic molecules

percent of sunlight captured by plants

0.8%

percentage of gross primary production used for production of biomass versus respiration/lost

45% new biomass, 55% respiration or lost as heat

Why are autotrophs inefficient at capturing solar energy?

- only certain wavelengths can be captured
- photosynthetic rates are lowered in certain biomes due to temperature, water availability

secondary production

energy use in herbivores

How do we measure energy transfer and requirements?

bioenergetics

energy flow

energy moves through ecosystems in a one-way fashion (open system)

energy in through _____, out through ____

in through photosynthesis, out through respiration (heat)

matieral/nutrient flow

materials cycle (closed system)

trophic efficiency

5-20%, limits number of links on food chain

which are more efficient biomass producers, ectoderms or endoderms?

ectoderms because they can spend less energy on cellular respiration and maintaining body heat

which are more efficient biomass producers, small mammals or large mammals?

large mammals because they have a smaller surface-area-to-volume ration and lose less heat, spend less energy on metabolism

energy flow pyramids always

have largest level at base and smallest at point

biomass/trophic level pyramids between grassland, forest, and ocean

grassland and forest show typical pyramid system (largest level is primary producer and smallest is secondary consumer), ocean has large primary consumer rather than producers

Why is the primary consumer level larger than primary producer level in ocean biomass/trophic level chart?

Quick turnover of primary producers due to zooplankton grazing

net primary production

(gross primary production) - (respiration by autotrophs)

net primary production is expressed as

energy or biomass added / year

net primary production is very high in

tropical rainforests and coral reefs

terrestrials net primary production is limited by

temperature, water, sunlight, nutrients

which marine environments have highest NPP?

shallow waters along coastlines (receives the most nutrients from rivers and upwelling currents)

Net Ecosystem Production (NEP)

(gross primary production) - (total respiration by community)

Systems that store carbon usually produce

O2

Limiting factors of primary production in ocean

nutrients, mainly nitrogen phosphorus, or iron

Eutrophication

rich in nutrients, organisms, and organic material

nutrient sink

where nutrients are stored

higher temperatures typically lead to ______ decomposition rates

higher

effect of deforestation on nutrient cycling

huge nitrogen loss, loss of calcium and potassium, fewer plants leads to more nutrient loss

examples of biogeochemical cycles

carbon, nitrogen, water, phosphorus and other minerals

biogeochemical cycles

a general model for cycling of materials in global ecological systems

four major nutrient reserves

biotic available, biotic unavailable, abiotic available, abiotic unavailable

bioavailability

the form of chemical that can be absorbed and metabolized by an organism

bioavailability varies by...

chemical and organism

what factors control the rate of nutrient cycling?

decomposition of detritus

decomposition rate is determined by...

1. abiotic conditions (oxygen availability, temperature, precipitation)
2. quality of detritus as a nutrient source for fungi, bacteria, and archaea
3. abundance and diversity of detritivores present

boreal forests

upper soil layer consists of partially decomposed detritus and organic matter (cold, wet conditions limit decomposer metabolic rates and organic matter builds up)

tropical wet forests

organic layer of soil is absent (moisture and heat allows decomposition to keep pace with detrital inputs)

Nutrients cycle _____ through boreal forests and _____ through wet tropical forests

slowly and quickly

inorganic unavailable forms of nitrogen cycle

N2, NO2i

inorganic available forms of nitrogen cycle

NH4, NO3

organic unavailable forms of nitrogen cycle

chitin?

organic available forms of nitrogen cycle

amino acids, nucleic acids

forms of nitrogen available to plants

NH4, NO3

forms of nitrogen available to animals

organic forms only

abiotic reservoir of nitrogen cycle

atmosphere (N2)

key processes of nitrogen cycle

nitrogen fixation by bacteria, uptake by plants

human contribution to nitrogen cycle

fertilizer

reservoirs of carbon cycle

sediments, oceans, biomass, atmosphere, sedimentary rock

the carbon cycle forms

all organic molecules

human contribution to carbon cycle

respiration, burning of fossil fuels

reservoirs of phosphorus cycle

marine sedimentary rock, soil oceans