CHAPTER 4 ECOLOGY POPULATION GENETICS AND NATURAL SELECTION STUDY GUIDE

abiotic

nonliving environment

biotic

living environment

who was visiting the Galapagos Islands and became convinced that various populations evolved from ancestral forms?

Charles Darwin

natural selection theory

1. organisms. beget like organisms 2. there are chance variations between individuals in a species. some variations are heritable 3. more offspring are produced each generation that can be supported by their environment. 4. some individuals, because of their physical or behavioral traits, have a higher chance of surviving and reproducing than other individuals in same population.

adaptation

an evolutionary process that changes the anatomy, physiology, or behavior resulting in improved ability of members of a population to live in a specific environment

genes

DNA segments that serve as the key functional units in hereditary transmission.

alleles

Different forms of a gene

it is the ___________ of alleles that creates variation in a population

variety

evolutionary ecology

the study of how interactions among organisms and between organisms and their environment evolve

locus

Location of a gene on a chromosome

____________ variation among individuals in a population results from the combined effects of genes and environment.

phenotypic

who are the scientists that worked at Stanford conducting widely sited studies of plant variation?

Jens Clausen, David Keck, and William Hiesey

Clausen and his team performed what experiment on the sticky cinquefoil (Potentilla glandulosa)?

common garden experiment

common garden experiment

individuals are all in a common environment so variation among them must be genetically based

phenotypic plasticity

the ability of an organism to change its phenotype in response to changes in the environment

ecotypes

populations with adaptations to unique environments

Microsatellite DNA

tandemly repetitive nuclear DNA, 10 to 100 base pairs long

population genetics

Study of allele frequency distribution and change under the influence of evolutionary processes

The theoretical foundations of population genetics were established early in the 20th century by 2 investigators named _________ and __________.

hardy, weinberg

the __________ equilibrium model helps identify evolutionary forces that can change gene frequencies in populations

hardy-weinberg

evolution

a change in gene frequencies in a population

allele frequencies

Proportions of different alleles in a population.

the sum of all allele frequencies must equal...

1

The Hardy-Weinberg principle states that if...

no evolution takes place, genotype frequencies can be predicted from allele frequencies by math formulas based on simple probabilities

A population at Hardy-Weinberg equilibrium will maintain _____________ allele frequencies generation after generation. It won't evolve for that trait.

constant

The conditions necessary for Hardy-Weinberg equilibrium are:

1. Random mating

2. No mutations

3. Large population size

4. No immigration

5. All genotypes have equal fitness

genetic drift

random change in allele frequencies that occurs in small populations

natural selection is...

differential survival and reproduction among phenotypes

Characteristics that are controlled by multiple genes are called...

polygenic traits

The mathematical treatment of continuously varying traits and how they respond to natural selection is known as...

quantitative genetics

stabilizing selection

Natural selection that favors average variants by acting against extreme phenotypes

fitness

the number of offspring, or genes, contributed by an individual to future generations

what's the consequence of stabilizing selection?

a population tends to sustain the same phenotype over time

directional selection

occurs when natural selection favors one of the extreme variations of a trait

what's the consequence of directional selection?

the average phenotype changes over time

disruptive selection?

favors individuals at both extremes of the phenotypic range (lower and upper) (bimodal distribution range)

what's the consequence of disruptive selection?

average phenotypes become less common and the population becomes phenotypically more diverse

heritability (h^2)

the proportion of total phenotypic variation in a trait that is attributable to genetic variance

heritability equation

H^2 = Vg/Vp

phenotypic variance can be broken down into two components:

H^2= Vg/(Vg+Ve)

phenotypic plasticity

the ability of one genotype to produce more than one phenotype when exposed to different environments

inbreeding

breed from closely related people or animals, especially over many generations.

population bottlenecks

a single sharp reduction in numbers causing a loss of diversity

founder effects

occur if the new population has lower genetic diversity than the original population