Chapter 15

Question 1

define extinction

Answer 1

all individuals in that species/genus/etc. have died out and left no descendants

Question 2

dissolution

Answer 2

water dissolves fossil leaving behind a cast

Question 3

carbonization

Answer 3

thin carbonized layer

Question 4

What are the right conditions fossilization requires?

Answer 4

Geological and abiotic conditions.

Most often occurs in sedimentary rocks

Question 5

What factors can disrupt the process of fossilization?

Answer 5

scavengers/predators
soft tissue preservation rare
abiotic factors break down organism

Question 6

Lagerstatten (resting place)

Answer 6

Large number of fossils found together due to perfect geological and biotic conditions

Question 7

Ediacaran fossils

Answer 7

Huge burst of new multicellular organisms

Question 8

Where do you look for fossils?

Answer 8

Look for sites that are prone to have fossils based of ideal geological and abiotic conditions
Look near previously identified sites
phylogenetic/ biogeographical reconstructions
combinations of above

Question 9

Law of superposition (relative aging)

Answer 9

Fossils found lower down in the sediment at a particular locality are older than those found closer to the surface

Question 10

Radiocarbon dating (absolute aging)

Answer 10

Isotope carbon-14 decays into carbon-12 at a steady state, half-life 5730 years.

Question 11

Potassium-14 to argon-40

Answer 11

(1.3 by half-life), volcanic in origin; date surrounding volcanic rocks around fossil

Question 12

Paleomagnetic dating

Answer 12

Changes in the earth’s magnetic field which is preserved in metal grains in rocks.

Question 13

Does a fossil represent the first or last appearance of the species?

Answer 13

NO

Question 14

Signore-Lipps effect

Answer 14

Time lag between the last known fossil and extinction;

result= extinction date is estimated to be earlier that it actually is

Question 15

“Forward smearing”

Answer 15

reworking of strata; mixing of layers

Question 16

Mass extinctions

Answer 16

Spike in extinction rates; 40-50% of all species & 5-8 in earth’s history

Question 17

Background extinction

Answer 17

extinction outside of mass extinction, 95% of all extinctions

Question 18

How is background extinction caused?

Answer 18

Mainly caused by predation, competition, diseases, climate change.

Question 19

endemic

Answer 19

native to only one area

Question 20

What can happen if natural selection favors traits in predators that make them efficient at capturing prey?

Answer 20

Can cause prey to go extinct; also cause an evolutionary arms race

Question 21

What can happen if new predators enter an area (natural or unnatural)?

Answer 21

Can extirpate native fauna

Question 22

What are the 5 big mass extinctions?

Answer 22

Ordovician, Devonian, Permian, Triassic, Cretaceous (K-T)

Question 23

How is extinction a double-edged sword?

Answer 23

Besides wiping out lineages and genetic variation, the evolutionary landscape changes opening up new opportunities for surviving lineages

Question 24

What are the 4 causes of loss in mass extinctions?

Answer 24

taxonomic diversity, morphological diversity, behavioral diversity, number of different types of niches

Question 25

Dead clade walking

Answer 25

Clade that survives a mass extinction event to only going extinct in the next geological time period

Question 26

K-T Mass Extinction aka Cretaceous-Tertiary

Answer 26

Occurred over very short period of time; supernova/ asteroid collision theories (iridium deposits)

Question 27

Permian Extinction

Answer 27

Greatest mass extinction, all walks of life hit hard, coral reefs depleted

Question 28

What caused Permian extinction?

Answer 28

Siberian traps- huge volcanic eruptions &

massive “greenhouse” effect due to CO2 release, so surviving species adapted to hypoxia

Question 29

How come species longevity has no effect on the probability of extinction

Answer 29

Extinction is a function of how well individuals in a species adapt to the current environment, not how well they adapted to past conditions

Question 30

What is the advantage of having a broader geographic range?

Answer 30

The less likely a taxon will go extinct

Question 31

Phyletic gradualism model

Answer 31

Adaptations that arise within a species are the result of slow gradual processes, where any variant that provides the slightest benefit slowly increases in frequency
ex. equine evolution

Question 32

cladogenesis

Answer 32

a new form that appears in the fossil record arising through branching speciation events

Question 33

anagenesis

Answer 33

a new form that appears in the fossil record arising through gradual modification WITHOUT branching speciation

Question 34

Punctuated equilibrium

Answer 34

predicts that a lot of evolutionary change takes place in short periods of time tied to speciation events
ex. Cambrian explosion

Question 35

Cambrian explosion (5 facts)?

Answer 35

-543-490 mya spike in number of species
-new body forms and shapes
most of the animal groups that have ever lived can be traced back to this time period

Question 36

What is Punctuated equilibrium in bryozoans tied to?

Answer 36

tied to changes in oceanic boundaries

Question 37

Cope’s rule

Answer 37

Species in mammalian clades tend to increase in body size over evolutionary time. (Doesn’t always hold up within mammals and across other groups)
general increase in organismal complexity

Question 38

What is the difference between passive & active trends?

Answer 38

Passive: no directional tendency to change, but the precursor starts at a minimum size which evo can’t take new lineages
Active: each lineage tends to increase in body size

Question 39

What two processes lead to active trends?

Answer 39

• trait values with each subclade shifting in parallel

- species selection

Question 40

Species selection

Answer 40

speciation and extinction rates that vary according to the value of the trait in question

Question 41

In what body size does speciation events take place more frequently?

Answer 41

Speciation events are more frequent among LARGER species

Question 42

Tree branches are longer in larger species, what does this indicate?

Answer 42

Fewer extinctions