Definitions chapter 5: Adaptation and natural selection

Question 1

Natural Selection

Answer 1

Differential success (reproduction and survival) of individuals that results in elimination of maladaptive traits from a population

Question 2

Evolution

Answer 2

Change in gene frequency through time resulting from natural selection and producing cumulative changes in characteristics of a population

Question 3

Adaptation

Answer 3

A genetically determined characteristic (behavioral, morphological, or physiological) that improves an organism’s ability to survive and reproduce under prevailing environmental conditions

Question 4

Gene

Answer 4

Unit material of inheritance; more specifically, a small unit of a DNA molecule, coded for a specific protein to produce one of the many attributes to species

Question 5

Allele

Answer 5

One of two or more alternative forms of a gene that occupies the same relative position or locus on homologous chromosomes

Question 6

Genome

Answer 6

The collective term for all the DNA in the cell

Question 7

Chromosomes

Answer 7

One of a group of threadlike structures of different lengths and sizes in the nuclei of cells of eukaryote organisms

Question 8

Locus

Answer 8

Site on a chromosome occupied by a specific gene

Question 9

Homozygous

Answer 9

Containing to identical alleles of a gene at the corresponding loci of a pair of chromosomes

Question 10

Heterozygous

Answer 10

Containing to different alleles of a gene, one from each parent, at the corresponding loci of a pair of chromosomes

Question 11

Genotype

Answer 11

Genetic constitution of an organism

Question 12

Phenotype

Answer 12

Physical expression of a characteristic of an organism, determined by both genetic constitution and environment

Question 13

Qualitative Traits

Answer 13

Phenotypic characteristics that fall into a limited number of discrete categories

Question 14

Quantitative Traits

Answer 14

Phenotypic characteristics that have a continuous distribution

Question 15

Phenotypic Plasticity

Answer 15

Ability to change form under different environmental conditions

Question 16

Norm Of Reaction

Answer 16

The set of phenotypes expressed by a single genotype across a range of environmental conditions

Question 17

Developmental Plasticity

Answer 17

Differences in phenotypic traits for a given genotype under different environmental conditions that reflect differences in the allocation of biomass to different tissues (leaves, stem, and roots) during the growth and development of the individual plant

Question 18

Acclimation

Answer 18

Reversible phenotypic changes in an individual organism in response to changing environmental conditions - a form of phenotypic plasticity

Question 19

Genetic Differentiation

Answer 19

When genetic variation occurs among subpopulations of the same species

Question 20

Gene Pool

Answer 20

The sum of all the genes of all individuals in a population

Question 21

Allele Frequency

Answer 21

The proportion of a given allele among all the alleles present at the locus in the population

Question 22

Genotype Frequency

Answer 22

The proportion of various genotypes in a population; compare gene frequency

Question 23

Target Of Selection

Answer 23

The phenotypic trait that natural selection acts directly upon

Question 24

Selective Agent

Answer 24

The environmental cause of fitness differences among organisms within a population with different phenotypes

Question 25

Directional Selection

Answer 25

Selection favoring individuals at one extreme of the phenotype in a population

Question 26

Stabilizing Selection

Answer 26

Selection favoring the middle in the distribution of phenotypes

Question 27

Disruptive Selection

Answer 27

Selection in which two extreme phenotypes in the population leave more offspring than the intermediate phenotype, which has lower fitness

Question 28

Mutations

Answer 28

Transmissible changes in the structure of a gene or chromosome

Question 29

Genetic Drift

Answer 29

Random fluctuation in allele frequency over time, due to chance alone without any influence by natural selection; important in small populations

Question 30

Migration

Answer 30

Intentional, directional, usually seasonal movement of animals between two regions or habitats; involves departure and return of the same individual ; a round-trip movement

Question 31

Gene Flow

Answer 31

Exchange of genetic material between populations

Question 32

Hardy-Weinberg Principle

Answer 32

The proposition that genotypic ratios resulting from random mating remain unchanged from one generation to another, provided natural selection, genetic drift, and mutation are absent

Question 33

Assortative Mating

Answer 33

When individuals choose mates non randomly with respect to their genotype, or more specifically, select mates based on some phenotypic trait

Question 34

Positive Assortative Mating

Answer 34

Occurs when mates are phenotypically more similar to each other than expected by chance

Question 35

Negative Assortative Mating

Answer 35

Occurs when mates are phenotypically less similar to each other than expected by chance

Question 36

Inbreeding

Answer 36

Mating among close relatives

Question 37

Inbreeding Depression

Answer 37

Detrimental effects of inbreeding

Question 38

Cline

Answer 38

A measurable, gradual change over a geographic region in the average of some phenotypic character, such as size or colorization; or it can be a gradient in genotypic frequency

Question 39

Ecotype

Answer 39

Subspecies or race adapted to a particular set of environmental conditions

Question 40

Geographic Isolates

Answer 40

Groups of populations that are semi-isolated from one another by some extrinsic barrier; compare subspecies

Question 41

Subspecies

Answer 41

Geographical unit of a species population, distinguishable by morphological, behavioral, or physiological characteristics

Question 42

Adaptive Radiation

Answer 42

Evolution from a common ancestor of divergent forms adapted to distinct ways of life

Question 43

Selective Breeding

Answer 43

Selecting individuals that exhibit a desired trait, and mating them with individuals exhibiting the same trait (or traits)