ch 25: phylogenies and the history of life

Question 1

what does position, size and connection among continents influence?

Answer 1

ocean circulation patterns, sea level, and global climate

Question 2

when do mass extinctions of marine animals occur?

Answer 2

when sea level dropped, exposing the continental shelves

Question 3

what are the current distributions of species a product of?

Answer 3

vicariance, dispersal, speciation and extinction

Question 4

fossil record

Answer 4

total collection of fossils that have been found throughout the world

Question 5

what does the fossil record provide direct evidence of?

Answer 5

what organisms from the past looked like, where they lived, and when they existed

Question 6

what conditions are fossils formed under?

Answer 6

organisms must be buried rapidly and decompose slowly

Question 7

habitat bias

Answer 7

organisms that live where sediment is actively being deposited are more likely to fossilize

Question 8

what kind of habitats are more likely to form fossils?

Answer 8

organisms that live in burrowing habitats are more likely to fossilize compared to organisms that live above ground

Question 9

taxonomic and tissue bias

Answer 9

organisms with hard parts are more likely to leave fossil evidence
- tissues with a tough outer coat that resists decay fossilize more readily

Question 10

temporal bias

Answer 10

recent fossils are more common than ancient fossils

Question 11

abundance bias

Answer 11

organisms that are abundant, widespread, and present for a long time leave evidence much more often than do species that are rare, local or ephemeral

Question 12

radiometric dating

Answer 12

used to assign absolute dates to events and species in the fossil record

Question 13

molecular clock hypothesis

Answer 13

rates of molecular change are constant enough to predict timing of evolutionary divergence

Question 14

molecular clock

Answer 14

uses the average rate at which a given gene or protein accumulates changes to measure the timing of divergences

Question 15

what must a molecular clock be?

Answer 15

calibrated using independent data, such as the fossil record, known divergences, or biogeographic dates

Question 16

adaptive radiation

Answer 16

the rapid production of many descendant species from a single lineage

Question 17

how is adaptive radiation inferred?

Answer 17

by phylogenetic analysis or observed in the fossil record as the sudden appearance of related diverse species

Question 18

what can two things can trigger adaptive radiations?

Answer 18

1. extrinsic factors: favorable new conditions in the environment
2. intrinsic factors: evolution of key morphological, physiological, or behavioral traits

Question 19

ecological opportunity

Answer 19

marked by availability of more or new types of resources

Question 20

innovations in evolution

Answer 20

evolution of key traits may have triggered many important diversification events in the history of life

Question 21

cambrian explosion

Answer 21

the most spectacular evolutionary change in the history of life

Question 22

how was the cambrian explosion documentated?

Answer 22

by major fossil assemblages mainly from Canada, China, and Austrailia

Question 23

fauna

Answer 23

a collection of animal species

Question 24

what triggered the cambrian explosion?

Answer 24

1. higher oxygen levels
2. rise of eukaryotic photosynthesis
3. evolution of predation
4. new niches create more new niches
5. new genes, new bodies

Question 25

higher oxygen levels

Answer 25

made aerobic respiration more efficient and supported larger, more active movements

Question 26

rise of eukaryotic photosynthesis

Answer 26

was enabled by increases in phosphorus and provided higher-quality food source for early animals

Question 27

the evolution of predation

Answer 27

exerted selection for shells, exoskeletons, rapid movement, and other defenses driving morphological divergence among prey animals

Question 28

new niches create new niches

Answer 28

exploitation of new niches created more new niches, driving speciation and ecological diversification

Question 29

new genes, new bodies

Answer 29

the earliest animals had few or no Hox genes - gene duplication and diversification increased the number of Hox genes in animals, yielding larger, more complex bodies

Question 30

mass extinction

Answer 30

the rapid extinction of a large number of diverse species around the world

Question 31

how many years does it take a species to be wiped out during mass extinction?

Answer 31

one million years

Question 32

what are mass extinctions caused by?

Answer 32

catastrophic events - sudden and temporary changes in the environment

Question 33

background extinction

Answer 33

the lower, average rate of extinction

Question 34

how does background extinction reduce populations to 0?

Answer 34

1. normal environmental change 2. emerging disease 3. predation pressure 4. competition with other species

Question 35

key event relevant to human history

Answer 35

1. origin of planet earth (4.5 billion years ago) 2. origin of life - prokaryotes (3.5 billion years ago) 3. origin of eukaryotes (2 billion years ago) 4. origin of multicellular animals (1 billion years ago) 5. cambrian explosion (540 million years ago) 6. origin of mammals (200 million years ago) 7. divergence between Human and Chimp (4-6 million years ago)