BIO CHAPTER 14

Why is genetic diversity important?

- diverse gene pool gives a population more flexibility to survive in a changing environment. - the more genetically diverse a populations is the more ways it has to adapt

Hardy-Weinberg equilibrium 5 necessary conditions

1.No mutation introducing new alleles into the population 2.No natural selection favoring some alleles over others 3.An infinitely large population size (and, therefore, no genetic drift) 4.No influx of alleles from neighboring populations (i.e., no gene flow) 5.Random mating of individuals

example of nonadaptive evolution

A mutation causes an increase in the incidence of antibiotic sensitivity in a population of Staphylococcus aureus. The gene pool of a drastically reduced population of northern elephant seals is vulnerable to chance events.

hybrid inviability

A postzygotic barrier in which hybrid zygotes fail to develop or to reach sexual maturity

founder effect

A type of genetic drift in which a small number of individuals leaves one population and establishes a new population, resulting in lower genetic diversity than in the original population.

bottleneck effect

A type of genetic drift that occurs when a population is suddenly reduced to a small number of individuals, and as a result alleles are lost from the population.

Gene flow is the movement of ________ between different populations of the _______ species

Alleles, same

nonadaptive evolution

Any change in allele frequency that does not by itself lead a population to become more adapted to its environment; the mechanisms of ____________ are mutation, genetic drift, and gene flow.

Types of genetic drifts

Bottleneck effect Founder effect

Each of the 13 species evolved from only 1 mainland species.

Galápagos finches

Describes a frequency of genotypes and phenotypes in a nonevolving population

Hardy-Weinberg equilibrium

behavior isolation

Isolation caused by differences in courtship or mating behaviors

inbreeding

Mating between closely related individuals. ___________ does not change the allele frequency within a population, but it does increase the proportion of homozygous individuals to heterozygotes.

reproductive isolation

Mechanisms that prevent mating (and therefore gene flow) between members of different species.

Non adaptive examples

Mutation Gene flow Genetic drift

How do different evolutionary mechanisms influence the composition of a gene pool?

Mutation-occur in the gamete-producing cells during DNA, when fertilized will enter the gene pool Migration (gene flow)- movement of alleles from one population to another. Genetic drift- allele changes by chance only, decrease genetic diversity of a population, more effect in smaler populations. natural selection- if the allele benifits the organism the frequency should increase.

Genetic diversity in a population is reflected by

Number of different alleles

genetic drift

Random changes in the allele frequencies of a population between generations; genetic drift tends to have more dramatic effects in smaller populations than in larger ones.

Inbreeding of closely related individuals occur is what type of populations

Small and isolated

Occurs when a gene pool seporated, gene flow is restricted, and populations diverge genetically over time

Speciation

gametic isolation

Sperm of one species may not be able to fertilize eggs of another species

Which of the following must be true if a population is undergoing evolution? Select the TWO answers that are correct. A high mutation rate is increasing genetic variability in the population. Genetic drift is causing random changes in the gene pool. The most advantageous of the alleles are increasing in frequency. The allele frequency of the population is changing over time. The gene pool is changing over the course of generations.

The allele frequency of the population is changing over time. The gene pool is changing over the course of generations.

biological species concept

The definition of a species as a population whose members can interbreed to produce fertile offspring.

speciation

The genetic divergence of populations, leading over time to reproductive isolation and the formation of new species.

gene flow

The movement of alleles from one population to another, which may increase the genetic diversity of a population.

inbreeding depression

The negative reproductive consequences for a population associated with having a high frequency of homozygous individuals possessing harmful recessive alleles.

Hardy-Weinberg principle

The principle that, in a nonevolving population, both allele and genotype frequencies remain constant from one generation to the next.

allele frequency

The relative proportion of an allele in a population.

population genetics

The study of the genetic makeup of populations and how the genetic composition of a population changes.

gene pool

The total collection of alleles in a population.

Which statements are true for both genetic bottlenecks and the founder effect?

They both result in a smaller gene pool. They both happen by chance.

What is a gene pool?

Total collection of alleles in a population

Can evolution be adaptive and non adaptive

True

What is an effect of gene flow?

an increase in the variety of alleles within the gene pool of a population

temporal isolation

form of reproductive isolation in which two populations reproduce at different times

In the Galapagos Islands, which of the following would have prevented the evolution of the many different species of finches

frequent migration of finches between the islands

hybrid infertility

hybrid offspring are sterile or have low fertility

How does the gene pool of an evolving population compare to the gene pool of a nonevolving population?

in an evolving population the gene pool is changing from generation to generation, in nonevolving population allele and genotype frequencies do not change over time. ( Hardy-Weinberg equilibrium)

mechanical isolation

mating is attempted, but morphological differences prevent its successful completion

Plants pollinated by the hummingbird do not receive pollen from plants pollinated by the bumble bee. This is an example of _____.

mechanical isolation

There are five characteristics that a population must have to NEVER experience a change in allele frequencies. Which of these is NOT one of them? no mutations a large population size natural selection no gene flow a lack of random mating

natural selection

Ecological isolation

species occur in the same area, but they occupy different habitats and rarely encounter each other

Two species of mice breed at different times of the year. This is an example of which type of isolation?

temporal

example of gene flow

the carriage of seeds between two separate urban forests by wildlife such as squirrels and rats that travel back and forth between the two

Hardy whinburg equilibrium equation

•Baseline to judge if a population is evolving •Hardy-Weinberg equation p2 + 2 pq + q2 = 1 •p2 is the frequency of homozygous dominants •2 pq is the frequency of heterozygotes •q2 is the frequency of homozygous recessives