Mechanisms of Evolution
This process occurs when individuals with certain inherited traits are more likely to survive and reproduce than others.
natural selection
p2+2pq+q2=1
This variable represents the frequency of the homozygous recessive genotype.
Structures in different species that are similar because of common ancestry, such as a human arm and a bat wing.
homologous structures
These structures, like the wing of a bat and the arm of a human, share a common ancestry but may have different functions.
Homologous Structures
This term describes the rapid elimination of species, which is the direct opposite of speciation.
Extinction
A random change in allele frequencies that affects small populations more than large ones
Genetic Drift
Which of the following is NOT a condition for Hardy-Weinberg equilibrium: Small population size, No mutations, Random mating, No natural selection?
Small population size
Remnants of features that served a function in the organism's ancestors.
vestigial structures
This type of speciation occurs when a population is divided by a geographic barrier, such as a mountain range or river.
Allopatric Speciation
This is the primary reason mass extinctions occur so rapidly, leaving little time for adaptation.
drastic/rapid environmental change/ habitat loss
When a few individuals become isolated from a larger population, this effect can lead to decreased genetic variation.
Founder Effect
If p=0.6, what is the frquency of the heterozygote (2pq)
0.48 (2 x 0.6 x 0.4)
The study of the past and present geographic distribution of species.
biogeography
This term refers to a group of species that includes an ancestral species and all of its descendants.
Monophyletic Group (clade)
The variety of living organisms in an ecosystem, which is reduced by extinction.
Biodiversity
This type of selection favors intermediate phenotypes, acting against both extreme variations.
stabilizing selection
A population of 100 individuals has 20 individuals with the recessive phenotype (aa). What is the frequency of the recessive allele q?
0.45 (sqrt(20/100) = sqrt(0.2) = 0.447
Similarities in these molecules, such as cytochrome, provide the most precise evidence of common ancestry.
DNA/Amino Acid sequences
These pre-zygotic barriers prevent mating because two species breed at different times of the day, seasons, or years.
Temporal Isolation
The current era of extinction, largely driven by human activity, is often referred to as this.
The Holocene/ Anthropocene Extinction
The movement of alleles between populations, which tends to reduce differences between them.
Gene flow
A sudden, catastrophic reduction in population size that changes allele frequencies.
bottleneck effect
This type of evidence includes transitional fossils that show intermediate states between ancestral forms and their descendants.
fossil record
On a phylogenetic tree, what does a "node" (branching point) specifically represent?
The most recent common ancestor of the lineages stemming from it
The balance between extinction and this process determines the Earth's overall biodiversity.
Speciation