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 __________________