Lecture 3: Macroevolution (and evidence for evolution)

Question 1

What did Darwin hypothesize was the reason for why the finches had different beak shapes in relation to food gathering?

Answer 1

Natural Selection

Question 2

What did Peter and Rosemary Grant discover about the ground finchs?

Answer 2

the beak depth variation among members of the population

Question 3

What did Peter and Rosemary Grant conclude about the year to year changes in average beak depth?

Answer 3

That the average beak depth represented evolutionary change resulting from natural selection.

Question 4

What are fossils?

Answer 4

The preserved remains of once-living organisms.

Question 5

How are rock fossils created?

Answer 5

1. Organism is buried in sediment
2. Calcium in bone or other hard tissue mineralizes
3. Surrounding sediment hardens to form rock

Question 6

Is fossilization common?

Answer 6

No!

Question 7

What organisms are not normally fossilized?

Answer 7

Those without a vertebrate

Question 8

How are some soft-bodied organisms preserved by their environment?

Answer 8

In some environments there is a absence of oxygen which prevents decomposition

Question 9

How are some insects, plants, and tiny lizards and frogs fossilized?

Answer 9

Though amber or fossilized resin of trees

Question 10

What is a major advantage of the fossil record?

Answer 10

Only fossils can tell us which organisms with which phenotypes existed at a given location at specific point of time prior to a few thousand years ago.

Question 11

What are some caveats when using fossil data?

Answer 11

1. fossil data is incomplete
2. spatial/ temporal bias
3. preservation bias

Question 12

What is some information we can get from fossils?

Answer 12

1. how structures were modified as they became adapted for specialized uses
2. they record the proliferation and extinction of evolutionary lineages and provide data on past geographical distributions

Question 13

What are some indirect data we can get from fossils?

Answer 13

1. Behavior
2. Physiology (scrolls of bone in nasal passages of early mammals show they have a well-developed sense of smell)
3. Ecology (teeth and dung provide data about the diets)
4. Climate (fossilized pollen and changing arrays of fossils reflect large-scale shifts in physical environments)

Question 14

How do geologists determine the absolute age of rocks?

Answer 14

Through isotopic dating

Question 15

What is radiometric dating?

Answer 15

Scientists measure the relative amounts of parent radioisotope and its breakdown products. By comparing this ratio with the isotope’s half-life, they can estimate the rock’s absolute age.

Question 16

Why are there gaps in the fossil record?

Answer 16

Because there is a low likelihood of fossil preservation and recovery.

Question 16

What demonstrates how major transitions in fossils occur?

Answer 16

Intermediate forms

Question 17

What are homologous structures?

Answer 17

Structures with different appearances and functions that are all derived from the same body part in a common ancestor.

Question 18

What are Vestigial structures?

Answer 18

structures that have no apparent function, but resemble structures ancestors possessed

Question 19

What is Biogeography?

Answer 19

It is the study of the geographic distribution of species

Question 20

What does Biogeography reveal?

Answer 20

That different geographical areas sometimes have groups of plants and animals of strikingly similar appearance, even though the organism may be only distantly related.

Question 21

What does natural selection appear to have favored?

Answer 21

Parallel evolutionary adaptations in similar environments.

Question 22

What is convergent evolution?

Answer 22

Similar forms having evolved in different, isolated areas because of similar selective pressures in similar environments.

Question 23

What did Darwin note on his voyage?

Answer 23

1. islands are often missing plants and animals common continents.
2. species present on islands often diverged from continental relatives
3. island species usually are more closely related to species on nearby continents.

Question 24

What did Darwin conclude from Voyage?

Answer 24

1. Many islands have never been connected to the mainland
2. Species arrive on islands by dispersing across the water
3. Dispersal from nearby areas is more likely than distant sources.
4. Species that can fly, float, or swim are more likely to inhabit islands
5. Colonizers often evolve into many species