Topic 5: Evolution by Natural Selection

Question 1

Natural Selection Summary

Answer 1

• Natural selection is a process in which individuals that have certain heritable traits survive and reproduce at a higher rate than other individuals.
• Natural selection can increase the frequency of adaptations that are favorable in a given environment
• If an environment changes, or if individuals move to a
  new environment, natural selection may result in adaptation to these new conditions and give rise to new species

Question 2

Darwin Made two points in “On the Origin of Species by Means of Natural Selection”

Answer 2

1. species show evidence of “descent with modification” from common ancestors (evolution)
2. natural selection is the mechanism for “descent with modification”

Question 3

Three principles of evolution

Answer 3

1. There is variation within a population of organisms and this variation can be inherited (passed to the next generation)
2. individuals with inherited traits that are better suited for growth and reproduction in a given environment contribute disproportionately to the next generation
3. natural selection is the process in which individuals with favourable traits are more likely to surviveand reproduce

Question 4

Georges Culvier

Answer 4

• Noted that strata were dissimilar to living organisms and that fossils changed between strata (extinction).
• proposed fossil record represented catastrophism (catastrophic events)
• did not believe in evolution
• a succession of life in strata happens because catastrophe leads to local extinction, and different species move into the area

Question 5

Jean-Baptiste Lamarck

Answer 5

• the apparent disappearance of species was one species changing into another (opposed to extinction)
• hypothesized that species evolved through inheritance of acquired characteristics

Question 6

inheritance of acquired characteristics

Answer 6

An organism can pass on characteristics that it acquired during its lifetime to its offspring

Question 7

Darwin’s observations during his voyage

Answer 7

• species traits matched the environment they inhabited
• fossils resembled living species from the same region and that living species resembled other species from nearby regions
• an uplift of rock happens after earthquakes ( influenced principles of geology)

Question 8

Natural Selection

Answer 8

a process in which individuals with favorable inherited traits are more likely to survive and reproduce

Question 9

large morphological gaps between
related groups could be explained
by:

Answer 9

branching process of biodiversity, and extinction events

Question 10

What explains the duality of unity and diversity in living organisms

Answer 10

natural selection

Question 11

Descent with modification

Answer 11

describes the origin of new species (speciation) form ancestral species

Question 12

The Galápagos finch species form a
_____ group, because they
descended from a _____________

Answer 12

monophyletic group, single common

ancestor

Question 13

Darwin’s observations of evolution:

Answer 13

1. Members of a population vary in their inherited traits
2. populations produce more offsprings than the environment can support, and many offspring fail to survive and reproduce

Question 14

Darwin’s inference of evolution:

Answer 14

1. individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment leave more offspring than other individuals
2. the unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations.

Question 15

Natural selection results in the ______ of populations to their environment

Answer 15

adaptation

Question 16

Types of variation

Answer 16

genotypic, phenotypic

Question 17

genotype

Answer 17

genetic variation among individuals caused by differences in genes or other DNA segments (not all variations of genotype are expressed)

Question 18

phenotypic variation

Answer 18

an organism’s observable characteristics are determined by the interaction of environmental factors and an organism’s genotype

Question 19

For natural selection to act on variation, it must be:

Answer 19

1. seen by the environment (expressed as a phenotype)

2. heritable (caused by a genotype)

Question 20

selective agents

Answer 20

environmental factors acting on populations to effect survival and/or reproduction of individuals in the population

Question 21

Selection pressure

Answer 21

When a selective agent consistently causes differences in survival and/or reproduction in a population