Diversity of Form and Function Lecture

Exam 1

What are the characteristics of animals

1. multicellular

2. heterotrophic = cannot produce its own food

3. internal digestion

4. movement and nervous system

5. monophyletic = ancestral species and all of its descendants

what are choanoflagellates

the closest living relative to animals

key outcome of the cambrian explosion

rapid burst of diversification establishing most basic modern marine animal body forms and phyla

punctuated equilibrium

evolutionary pattern where there are long periods of time where there is no morphological change, but every so often there are short periods of time with rapid evolutionary change

factors promoting diversification during the cambrian

1. increase in global O2

2. increase in ocean Ca2+

3. expansive continental shelves/shallow lagoons

4. evolution of hox genes

hox genes function

regulate embryonic development and control body function pattern positioning along the anterior-posterior axis

acanthodians vs placoderms

• acanthodians are ancestors of modern sharks

• placoderms are ancestors of bony fishes

major environmental challenges for early land vertebrates

1. gravity

2. desiccation (drying out)

3. breathing in gas versus water

what period came after the cambrian event

ordovician

what things happened during early ordovician

modern spinal column forms which leads to the 1st fishes

• plants colonize land first

• animals colonize land second

what things happened during late ordovician

• bony jaws evolved

• large predators

• 2 major lineages formed (acanthodians and placoderms)

what things happen during the devonian period

• diversification of sharks and bony fishes

• placoderms become extinct

• 1st lobe-finned fishes evolve (1st vertebrate colonization of land)

what things happen at the end of the triassic period

• bony fishes diversify

• extinction event

what things happen during the jurassic period

• increase in body size

• following the extinction event of the triassic, there are open habitats/niches and more large reptiles for prey

what things happen during the cretacious period

• closest ancestors of modern fishes evolved

• more large predators

what is the cretaceous-paleogene

the “K-Pg boundary”

• astroid that took out all the dinosaurs

• bony fishes survived and adapted to the open habitats

when did lobe-finned fishes arise and diversify

in the devonian period

lobe-finned fishes and land colonization

lobe-finned fishes were the 1st to colonize land at the end of the devonian period

skeletal modifications in lobe-finned fishes

evolution brought modifications to the girdles, vertebral column, and skull

muscle modifications in lobe-finned fishes

muscles in the fins adapted to support body weight on land

lobe-finned fishes led to the evolution of _____

tetrapods (amphibians, mammals, birds, crocodiles, reptiles)

direct ancestor of amphibians

sarcopterygian ancestor (lobe-finned fishes)

key adaptations of amphibians from their direct ancestor

1. lungs

2. appendages with internal support away from trunk

aquatic origins of early amphibian species

fully aquatic and inhabited shallow water with dense vegetation

challenges of living on land for amphibians

1. gravity

2. desiccation

3. different oxygen medium

what period did birds, crocodilians, and reptiles originate

pennsylvanian period

what lineage do birds, crocodilians, and reptiles belong to

sauropsid lineage

what did the sauropsid lineage give rise to

• dinosaurs

• modern birds

• crodilians

• snakes,lizards

what period did mammals originate from

pennsylvanian period

what lineage do mammals belong to

synapsid lineage

what was important about the jurassic period in terms of mammals

the specific mammal lineage that led to all modern mammals formed during the jurassic period

what is the major evolutionary trend in animal evolution

increasing structural and functional complexity

centralization

evolutionary transition from a scattered nerve net to a structured, centralized nervous system

cephalization

sensory organs became more concentrated towards the anterior (head) of organisms

what is the timeline of all extinction events from oldest to most recent

1. late ordovician

2. late devonian

3. permian-triassic

4. triassic-jurassic

5. cretaceous-paleogene

what was the largest extinction event and why

end permian/permian triassic; this extinction event had a large magnitude of change in global temperatures

what caused the late ordovician extinction

volcanism and anoxia

what caused the late devonian extinction

ocean anoxia, global cooling fluctuations

what caused the permian-triassic extinction

global warming, ocean acidification

what caused the triassic-jurassic extinction

volcanic eruptions, global warming, ocean acidification

what caused the cretaceous-paleogene extinction

an asteroid

geologic eons (oldest to youngest)

1. precambrian

2. paleozoic

3. mesozoic

4. cenozoic

periods of the precambrian (oldest to youngest)

1. hadean

2. archean

3. paleoproterozoic

4. mesoproterozoic

5. neoproterozoic

periods of the paleozoic (oldest to youngest)

1. cambrian

2. ordovician

3. silurian

4. devonian

5. mississippian

6. pennsylvanian

7. permian

periods of the mesozoic (oldest to youngest)

1. triassic

2. jurassic

3. cretaceous

periods of the cenozoic (oldest to youngest)

1. paleocene

2. eocene

3. oligocene

4. miocene

5. pliocene

6. pleistocene

7. holocene

homeostasis

requires energy; the stability of the internal environment of an individual

why is thermoregulation important?

temperature affects the rates for enzyme reactions, temperature variations can be extensive in some ecosystems

what does the Q10 temperature coefficient measure

it measures the sensitivity of a reaction or process to a change in temperature

how to calculate the Q10 coefficient

the rate of a reaction at a given temperature divided by the rate of a reaction at the temperature 10 degrees less

homeotherms

animals that keep a steady internal body temperature ; regulators

what are some examples of homeotherms

birds and mammals

poikilotherms

animals that vary their body temperature along with the environment; conformers

examples of poikilotherms

frogs, lizards, fish

key physiological parameters regulated by homeostasis

• temperature

• pH

• blood glucose

• blood pressure

• heart/respiratory rate

• concentrations of O2, CO2, Na+, Ca2+

thermoneuatral zone

range of external temperatures in which a homeotherms metabolic rate is minimal and does not change with external temperature

endotherm

animal that gets heat primarily from internal sources (metabolism)

• may or may not be successful at maintaining a constant temperature

ectotherm

animal that obtains heat primarily from external sources

• may have body temperatures higher or lower than external temperatures

heterotherm

animal that functions homeothermically during certain times but hibernates during winter/cold months

what is the importance of brown adipose tissue

specialized fat tissue used in mammals for nonshivering thermogenesis to produce heat

blood vessel physiological response to cold (vasoconstriction)

constriction near the skin to minimize heat loss to the environment

blood vessel physiological response to heat (vasodilation)

dilation near the skin to increase heat transfer away from the body

4 pathways of thermal exchange

radiation, evaporation, convection, conduction

conduction

direct heat transfer between solids in contact

convection

heat transfer driven by the movement of air or fluid across a surface

microenvironment

a small, specific environment within a larger habitat that provides unique climate conditions (microclimate)

countercurrent heat exchange

vessels flowing parallel and opposite of each other to minimize heat loss

negative feedback control system

stimulus causing a deviation from a set point triggers a response to reverse the change, restoring stability

positive feedback control system

mechanism that amplifies or accelerates a process until a specific endpoint stops the loop

thermoregulatory adaptation: surface area to volume ratio

high surface area to volume ratios (small animals) lose or gain heat more rapidly, low surface area to volume ratios (large animals) lose or gain heat more slowly