Chapter 14

Front 1

Adaptation

Back 1

1.The evolutionary process by which a population as a whole becomes better matched to its habitat.

2. An inherited characteristic - structural, biochemical, or behavioral - that enables an organism to funcion well and therefore to survive and reproduce better than competitors lacking the characterisitc.

Front 2

Allele

Back 2

One of two or more alternative versions of a gene that exist in a population of organisms. Each allele has a DNA sequence that is somewhat different from that of all other alleles of the same gene.

Front 3

Allele frequency

Back 3

The proportion (percentage) of a particular allele in a population.

Front 4

Aritificial selection

Back 4

A process in which only individuals that possess certain characteristics are allowed to breed. Artificial selection is used to guide the evolution of crop plants and domestic animals.

Front 5

Directional selection

Back 5

A type of natural selection in which individuals with one extreme of an inherited characteristic have an advantage over other individuals in the population, as when large individuals produce more offspring than do small and medium-sized individuals.

Front 6

Disruptive selection

Back 6

A type of natural selection in which individuals with one extreme of an inherited characteristic have an advantage over other individuals in the population, as when large individuals producde more offspring than do small and medium-sized individuals.

Front 7

Extinction

Back 7

The demise of a species or other, larger group of organisms.

Front 8

Fixation

Back 8

In genetics, the removal of all alleles within a population at a particular genetic locus except one. The allele that remains has a frequency of 100 percent.

Front 9

Fossil

Back 9

Preserved remains or an impression of a formerly living organism. Fossils document the history of life on earth, showing that many organisms from the past were unlike living forms.

Front 10

Founder effect

Back 10

A genetic bottleneck that results when a small group of individuals from a larger source poulation establishes a new population far from the original population.

Front 11

Gene flow

Back 11

The exchange of alleles between different populations.

Front 12

Gene pool

Back 12

The sum of all the genetic information carried by all the individuals in a population.

Front 13

Genetic Bottleneck

Back 13

A drop in the size of a population that results in low genetic variation or causes harmful alleles to reach a frequency of 100 percent in the population.

Front 14

Genetic drifit

Back 14

The natural process in which chance events cause certain alleles to increase or decrease in a population. The genetic makeup of a population undergoing genetic drift changes at a random over time, rather than being shaped in a nonrandom way by natural selection.

Front 15

Genetic variation

Back 15

The allelic differences among the individuals of a population.

Front 16

Mutation

Back 16

A change in the sequence of an organism's DNA. Because new alleles arise only by mutation, mutations are the original source of all genetic variation.

Front 17

Natural selection

Back 17

An evolutionary mechanism in which the individuals in a population that possess particular inherited characteristics survive and reproduce at a higher rate than other individuals in the population because those characteristics enable the individuals to function optimally in their particular habitat. It's the only evolutionary mechanism that consistently improves the survival and reproduction of the organism in its environment.

Front 18

Pangaea

Back 18

Ancient supercontinent

Front 19

Plate tectonics

Back 19

How crust moves around

Front 20

Sexual dimorphism

Back 20

A distinct difference in apperance between the males and females of a species.

Front 21

Sexual selection

Back 21

A type of natural selection in which individuals that differ in inherited characteristics differ, as a result of those characteristics, in their ability to get mates.

Front 22

Stabalizing selection

Back 22

A typeof natural selection in which individuals with intermediate values of an inheritied characteristic have an advantage over other individuals in the population, as when medium sized individuals produce offspring at a higher rate than do small or large individuals.