Chapter 11 Flashcards
Gene pool
The collection of alleles found in all of the individuals of a population
Allele frequency
A measure of how common a certain allele is in the population
Mutation
A random change in the DNA of a gene
Recombination
Forms new combinations of alleles
Hybridization
The crossing of two different species
Normal distribution
Highest frequency near average value and lower frequency toward each extreme value
Microevolution
The observable change in the allele frequencies of a population over time
Directional selection
one extreme phenotype is favored by natural selection
Stabilizing selection
intermediate phenotypes are favored by natural selection
Disruptive selection
both extreme phenotypes are favored by natural selection
What are the three pathways of natural selection
Directional, stabilizing, and disruptive selection
Gene flow
The movement of alleles from one population to another
When does gene flow occur
Occurs when individuals join new populations and reproduce.
Genetic drift
Changes in allele frequencies that are due to chance
How does genetic drift work
Causes a loss of genetic diversity
Bottleneck effect
Describes the effect of a disruptive event that leaves only a few survivors in a population
When does the bottleneck effect occur
Occurs after an event greatly reduces the size of the population
When does sexual selection occur
Occurs when certain traits increase mating success
Intra selection
Competition among males, the winner wins the female
Intersection
Males display certain traits that attract the female
What are the five conditions required to be in equilibrium
Very large population-no genetic drift
no emigration or imigration-no gene flow can occur
no mutations-no new alleles can be added to the gene pool
random mating-no sexual selection can occur
no natural selection- all traits must equally aid in survival
what is the Hardy-Wienberg equations
1) p2+2pq+q2=1
2) p+q=1
what is the p2
homozygous dominant
what is the 2pq
heterozygous
what is the q2
homozygous recessive
what is the p
dominant alleles
what is the q
frequency of recessive alleles
what are the five factors that can lead to evolution
Genetic dirift, gene flow, mutations, sexual selection, and natural selection
what is genetic drift
allele frequencies can change due to chance alone
what is gene flow
the movement of alleles from one population to another
what creates genetic variation needed for evolution
mutations
what is it called when certain traits may improve mating success
sexual selection
what is it called when certian traits may be an advantage for survival
natural selection
reproductive isolation
occurs when members of different populations can no longer mate successfully
speciation
the rise of two or more species from one existing species
behavioral isolation
isolation caused by differences in courtship or mating behaviors
geographic isolation
physical barriers that divide a population into two or more groups
temporal isolation
exists when timing prevents reproduction before populations
which type of isolation involves factors of time
temporal isolation
which type of isolation involve mating or courtship rituals
behavioral isolation
which type of isolation can isolation can involve physical barriers
geographic isolation
convergent evolution
evolution toward similar characteristics in unrelated species
divergent evolution
closely related species evolve in different directions they become increasingly different
example of convergent evolution
wings on birds and insects
example of divergent evolution
red fox and the kit fox
what is coevolution
the process in which two or more species evolve in response to changes in each other
extinction
the elimination of a species from earth
punctuated equilibrium
states that episodes of speciation occur suddenly in geologic time and are followed by long periods of little evolutionary change
adaptive radiation
the rapid evolution of many diverse species from ancestral species
