Chapter 5: Adaptation and Natural Selection

Question 1

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

Answer 1

natural selection

Question 2

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

Answer 2

adaptation

Question 3

Genetic contribution by an individual’s descendants to future generations

Answer 3

fitness

Question 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 of a species

Answer 4

genes

Question 5

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

Answer 5

alleles

Question 6

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

Answer 6

selective agent

Question 7

The phenotypic trait that natural selection acts directly upon

Answer 7

target of selection

Question 8

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

Answer 8

directional selection

Question 9

Selection favoring the middle in the distribution of phenotypes

Answer 9

stabilizing selection

Question 10

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

Answer 10

disruptive selection

Question 11

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

Answer 11

assortative mating

Question 12

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

Answer 12

negative assortative mating

Question 13

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

Answer 13

positive assortative mating

Question 14

Mating among close relatives

Answer 14

inbreeding

Question 15

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

Important in small populations

Answer 15

genetic drift

Question 16

A measurable, gradual change over a geographic region in the average of some phenotypic character, such as size or coloration

Or it can be a gradient in genotypic frequency

Answer 16

cline

Question 17

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

Compare subspecies

Answer 17

geographic isolate

Question 18

Subspecies or race adapted to a particular set of environmental conditions

Answer 18

ecotype

Question 19

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

Answer 19

subspecies

Question 20

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

Answer 20

adaptive radiation

Question 21

Ability to change form under different environmental conditions

Answer 21

phenotypic plasticity

Question 22

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

Answer 22

norm of reaction

Question 23

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

Answer 23

developmental plasticity

Question 24

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

Answer 24

acclimation

Question 25

Let’s talk about trade-offs and constraints

Answer 25

“…the fitness of any phenotype is a function of the prevailing environmental conditions; the characteristics that maximize the fitness of an individual under one set of environmental conditions generally limit its fitness under a different set of conditions.”

“The limitations on the fitness of a phenotype under different environmental conditions are a function of trade-offs imposed by constraints that can ultimately by traced to the laws of physics and chemistry.”

“The characteristics enabling a species to survive, grow, and reproduce under one set of conditions limit its ability to do equally well under different environmental conditions.”

Question 26

The process of directly altering an organism’s genome

Answer 26

genetic engineering