25: Evolution by Natural Selection

Question 1

Evolution

Answer 1

(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 2

Population

Answer 2

A group of individuals of the same species living in the same geographic area at the same time.

Question 3

Population Thinking

Answer 3

The ability to analyze trait frequencies, event probabilities, and other attributes of populations of molecules, cells, or organisms.

Question 4

Descent with modification

Answer 4

The phrase used by Darwin to describe his hypothesis of evolution by natural selection. He meant that species that lived in the past are the ancestors of the species existing today, and that species change through time.

Question 5

fossil

Answer 5

Any physical trace of an organism that existed in the past. Includes tracks, burrows, fossilized bones, casts, and so on.

Question 6

fossil record

Answer 6

All of the fossils that have been found anywhere on Earth and that have been formally described in the scientific literature.

Question 7

extant species

Answer 7

A species that is living today.

Question 8

Sedimentary rocks

Answer 8

A type of rock formed by gradual accumulation of sediment, particularly sand and mud, as in riverbeds and on the ocean floor. Most fossils are found in sedimentary rocks.

Question 9

geological time scale

Answer 9

The sequence of eons, eras, and periods used to describe the geologic history of Earth.

Question 10

extinct species

Answer 10

A species that has died out.

Question 11

transitional feature

Answer 11

A trait that is intermediate between a condition observed in ancestral (older) species and the condition observed in derived (younger) species.

Question 12

vestigial trait

Answer 12

A reduced or incompletely developed structure that has no function or reduced function, but is clearly similar to functioning organs or structures in closely related species.

Question 13

phylogenetic tree

Answer 13

A branching diagram that depicts the evolutionary relationships among species or other taxa.

Question 14

homology

Answer 14

Similarity among organisms of different species due to their inheritance from a common ancestor. Features that exhibit such similarity (e.g., DNA sequences, proteins, body parts) are said to be homologous. Compare with homoplasy.

Question 15

genetic homology

Answer 15

Similarity in DNA nucleotide sequences, RNA nucleotide sequences, or amino acid sequences due to inheritance from a common ancestor.

Question 16

developmental homology

Answer 16

A similarity in embryonic form, or in the fate of embryonic tissues, that is due to inheritance from a common ancestor.

Question 17

structural homology

Answer 17

Similarities in adult organismal structures (e.g., limbs, shells, flowers) that are due to inheritance from a common ancestor.

Question 18

morphology

Answer 18

The shape and appearance of an organism’s body and its component parts.

Question 19

natural selection

Answer 19

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

Question 20

artificial selection

Answer 20

Deliberate manipulation by humans, as in animal and plant breeding, of the genetic composition of a population by allowing only individuals with desirable traits to reproduce.

Question 21

fitness

Answer 21

The ability of an individual to produce viable offspring relative to others of the same species.

Question 22

adaptation

Answer 22

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

Question 23

tuberculosis

Answer 23

A disease of the lungs caused by infection with the bacterium Mycobacterium tuberculosis.

Question 24

natural experiment

Answer 24

A situation in which a natural change in conditions enables comparisons of groups, rather than a manipulation of conditions by researchers.

Question 25

acclimatization

Answer 25

A change in an individual’s phenotype that occurs in response to a change in natural environmental conditions.

Question 26

acclimation

Answer 26

A change in a study organism’s phenotype that occurs in response to laboratory conditions.

Question 27

genetic correlation

Answer 27

A type of evolutionary constraint in which selection on one trait causes a change in another trait as well; may occur when the same gene(s) affect both traits.

Question 28

fitness trade-off

Answer 28

In evolutionary biology, an inescapable compromise between two traits that cannot be optimized simultaneously. Also called trade-off.