Topic 12 - Natural Selection

Question 1

Adaptation (process)

Answer 1

Change in the phenotypic characteristics of populations over time, due to natural selection.

Question 2

Adaptation (trait)

Answer 2

Any heritable trait that increases the fitness of an individual with that trait, compared with individuals without that trait, in a particular environment.

Question 3

Evolution

Answer 3

(1) The theory that all organisms on Earth are related by common ancestry and that they have changed over time, and continue to change, via natural selection and other processes. (2) Any change in the genetic characteristics of a population over time, especially a change in allele frequencies.

Question 4

Biological fitness

Answer 4

The ability of an individual to produce surviving, fertile offspring, relative to that ability in other individuals in the population.

Question 5

Fossil record

Answer 5

Provides evidence of change in the history of a species, since sequential transitional forms can be found on sequential geological strata, which allows to have an approximate date for when the different ancestors were alive and the type of environment in which they lived.

Question 6

Homology

Answer 6

Similarity among organisms of different species due to shared ancestry. Features that exhibit such similarity (e.g., DNA sequences, proteins, body parts) are said to be homologous. It provides evidence in favour of evolution because shared ancestry is the simplest (most parsimonious) explanation for the evolution of these similarities.

Question 7

Intersexual selection

Answer 7

A type of sexual selection in which an individual of one sex chooses a particular individual of the other sex for mating (usually occurs through female choice)

Question 8

Intrasexual selection

Answer 8

A type of sexual selection driven by competition among members of one sex (usually male-male) for an opportunity to mate.

Question 9

Macro-Evolution

Answer 9

The emergence of new species. It could happen quickly (E.g., as in allopolyploids) or take millions of years.

Question 10

Micro-evolution

Answer 10

Evolution that occurs at the population level, resulting from changes in allele frequencies.

Question 11

Overpopulation

Answer 11

Results from populations producing more offspring than the environment can support, and generates strong competition for resources such as food, shelter and mating sites, making certain individuals unable to survive and reproduce.

Question 12

Natural selection

Answer 12

The process by which individuals with certain heritable traits tend to produce more surviving offspring that individuals without those traits, often leading to a change in the genetic makeup of the population. A major mechanism of evolution.

Question 13

Disruptive selection

Answer 13

A mode of natural selection that favours extreme phenotypes at both ends of the range of phenotypic variation. Increases overall genetic variation in a population.

Question 14

Directional selection

Answer 14

A mode of natural selection that favours one extreme phenotype with the results that the average phenotype of a population changes in one direction. Generally reduces overall genetic variation in a population.

Question 15

Stabilizing selection

Answer 15

A mode of natural selection that favours phenotypes near the middle of the range of phenotypic variation. Reduces overall genetic variation in a population.