Chapter 21

Question 1

Beaks of Darwin’s Finches

Answer 1

Darwin collected 31 specimens from 3 islands in the Galápagos Islands​

Darwin not an expert on birds.​

Took them back to England for identification.​

Told his collection was a closely related group of distinct species.​

All were similar except for beak characteristics.​

In all, 14 species now recognized.​

Question 2

3 conditions of natural selection

Answer 2

Phenotypic variation must exist in the population.​

This variation must lead to differences among individuals in lifetime reproductive success.​

Phenotypic variation among individuals must be genetically transmissible to the next generation.

Question 3

Peter and Rosemary Grant

Answer 3

Studied medium ground finch on island called Daphne Major​

Found beak depth variation among members of the population

Question 4

Industrial melanism

Answer 4

Phenomenon in which darker individuals come to predominate over lighter ones

Question 5

Artificial Selection

Answer 5

Change initiated by humans

Question 6

Experimental selection

Answer 6

Scientists have imposed selection

Question 7

Agricultural selection

Answer 7

Differences have resulted from generations of human selection for desirable traits, such as greater milk production and larger corn ear size​

Question 8

Domestication

Answer 8

Human-imposed selection has produced a variety of cats, dogs, pigeons, and others​

Question 9

Fossil Evidence of Evolution

Answer 9

Fossils are the preserved remains of once-living organisms​

Rock fossils are created when three events occur​

Organism buried in sediment.​

Calcium in bone or other hard tissue mineralizes.​

Surrounding sediment hardens to form rock.

Question 10

Estimating the age of fossils

Answer 10

In Darwin’s day, rocks were dated by position relative to one another​

Today geologists determine the absolute age of rocks using isotopic dating

Question 11

Evolutionary transitions

Answer 11

gaps in the fossil record

Question 12

Homologous structures

Answer 12

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

Question 13

Early embryonic development

Answer 13

Strongest anatomical evidence supporting evolution comes from comparisons of how organisms develop​

Embryos of different types of vertebrates, for example, often are similar early on, but become more different as they develop

Question 14

Imperfections

Answer 14

some organisms do not appear perfectly adapted

Question 15

Pseudogenes​

Answer 15

Fossil genes; traces of previously functioning genes​

Question 16

Vestigial structures

Answer 16

Vestigial structures have no apparent function, but resemble structures ancestors possessed​

Question 17

Biogeography

Answer 17

Study of the geographic distribution of species​

Question 18

Convergent evolution

Answer 18

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

Question 19

Darwin noted on his voyage that

Answer 19

Islands are often missing plants and animals common on continents.​

Can live there if introduced​

Species present on islands often diverged from continental relatives.​

Occupy niches used by other species on continents​

Island species usually are more closely related to species on nearby continents.

Question 20

Darwin’s Critics 7 principal objections

Answer 20

“Evolution is not solidly demonstrated”​

“There are no fossil intermediates”​

The intelligent design argument​

“Evolution violates the Second Law of Thermodynamics”​

“Proteins are too improbable”​

“Natural selection cannot explain major changes”​

The irreducible complexity argument