Genetics Chapter 21

one species splits into two (or more) species

cladogenesis

occurs when populations have incompatible reproductive organs

define mechanical isolation

Intermediate phenotypes are favored

define stabilizing selection

Occurs when populations mate at different times

define temporal/seasonal isolation

Evolutionary changes within populations of species

microevolution

Similar genotypes more likely to mate than dissimilar ones

positive assortative

Group of individuals belonging to same species, live in the same geographical area and can interbreed

population

selection mulation gene flow sexual selection genetic drift

the ideal population has no: (smgsg)

Commonly affects genotype frequencies in population genetics

define inbreeding

inbreeding

A genetic bottleneck 12,000 years ago led to ______ in cheetahs, causing deleterious recessive alleles to become much more common.

genetic bottleneck

A population of fish has and variety of body colors and patterns. After an oil spill, only white fish with red stripes remain. What is this an example of?

founder effect

A species of beetles have different horn shapes. A group of two-pronged horn beetles are in log that floats to a remote island. A population of beetles form on the island and they all have two-pronged horns. What is this an example of?

Sexual dimorphism

Female spiders are usually significantly larger than male spiders. This phenomena is called _________.

p2 + 2pq + q2 = 1

Hardy-weinberg law

first generation hybrids are viable, but subsequent generations have lower fitness

Hybrid breakdown

different species can produce a viable offspring, but that offspring cannot reproduce

Hybrid sterility

an embryo is produced, but cannot survive development

Hybrid unviability

Disruptive selection

In a species of Galapagos finch, thick beaked individuals excel at cracking nuts, while thin beaked individuals excel at picking out grubs from trees. Individuals with intermediate beaks aren't good at either task. This is an example of what?

0.42

In snapdragons, the red and white flower alleles exhibit incomplete dominance. If the frequency of the red alleles is 0.3, what frequency of pink flowers do you expect in the population?

0.16

Opossums can be grey or white, with the grey allele being dominate. If the frequency of the grey allele is 0.6, what frequency do you expect for white opossums?

sexual selection

Peahens prefer peacocks with large and colorful tails, so those peacocks get to mate more frequently. This is an example of

unviability, sterility, breakdown

Postzygotic barriers: hybrid ________________

Create reproductive isolation even when members of two population mate with each other because the hybrids are sterile

Postzygotic isolating mechanisms

stabilizing selection

SS individuals have normal hemoglobin and are susceptible to malaria. Ss individuals have mostly normal hemoglobin and are resist to malaria. ss individuals have sickle cell anemia. This is an example of _______.

0.18

The frequency of a genetic disorder caused by a recessive allele is 0.01 in a population. What is the frequency of carriers are in the population?

Behavioral isolation

Two groups of jumping spider don't mate because of differences in their courtship dances is an example of

frequency of heterozygous genotype

What does 2pq represent?

frequency of dominant allele

What does p represent?

frequency of homozygous dominant (AA)

What does p2 represent?

frequency of recessive allele

What does q represent?

frequency of homozygous recessive (aa)

What does q2 represent?

Ornithodirans

What is the last common ancestor of sauropods and pterosaurs?

hybrid breakdown

When some varieties of rice are crossed, the hybrids are viable, but subsequent generations are smaller and have less fitness. This is an example of what?

C

Which of the follow represents a period of anagenesis?

selection against intermediate phenotypes, both extremes are selected for

define disruptive selection

microevolution

White clover plants produce hydrogen cyanide gas in response to herbivore insects feeding on them, deterring or even killing them. Recently white clover in urban areas was found to lack this mechanism. Its thought that since there are less herbivore insects in urban areas, the plant can save energy and resources by not producing hydrogen cyanide. This would be considered an instance of ______.

occurs when two populations occupy different habit

define ecological isolation

one species transforms into another after a period of statis

anagenesis

behaviors unique to a species are effective barriers to mating

define behavioral isolation

a trait at extreme end of spectrum isselected for or against

define directional selection

An individual's genetic contribution to future generations

fitness

Genetic information carried by members of population, often has high degree of heterozygosity (ex. domestic dog)

gene pool

high rates of reproductive success

high fitness genes have

Evolutionary events leading to emergence of new species and other taxonomic groups

macroevolution

Measure rate of evolutionary change in terms of amino acid or nucleotide sequences to estimate time of divergence

molecular clock

Dissimilar genotypes are more likely to mate

negative assortative

Genetic differences among present-day species can be used to reconstruct their evolutionary histories

phylogeny

Prevent mating from taking place (individuals dont see each other as mates or at all)

prezygotic isolating mechanisms

•formation of new species caused by mutation, migration, and drift

speciation

population variance, mean

stabilizing selection reduces ___________________ over time, but not the __________________