Evolution and Processes
All the different alleles present in a population at one time.
What is a gene pool?
The full spectrum of observable physical, physiological, or behavioral traits present within a population, upon which natural selection acts.
What is phenotypic range?
A group of similar organisms that can interbreed to produce fertile, viable offspring.
What is a species?
Isolating factors that stop mating or fertilization from happening in the first place
What are prezygotic isolating mechanisms?
Body parts in different species that share the same ancestral layout, even if used for different functions.
What are homologous structures?
The main process that creates entirely new alleles in a population.
What is mutation
Natural selection that favors the average phenotype and removes the extreme traits.
What is stabilising selection?
The transfer of genes into or out of a population caused by the movement of individuals or their gametes.
What is gene flow?
Isolating factors that act after fertilization to prevent a hybrid from becoming a fertile adult.
What are postzygotic isolating mechanisms?
Body parts in different species that do the same job but evolved independently due to similar environmental pressures.
What are analogous structures?
Random changes in allele frequencies that have a much bigger effect on small populations.
What is genetic drift?
Selection that shifts toward one extreme phenotype because the environment has changed.
What is directional selection?
Speciation that happens in the exact same location without any geographic barrier.
What is sympatric speciation?
A postzygotic barrier where the hybrid zygote forms but dies before reaching adulthood.
What is hybrid inviability?
The rapid evolution of one common ancestor into many new species to fill open ecological niches.
What is adaptive radiation?
When a small group breaks off to start a new population, carrying a different gene pool than the original group.
What is the founder effect?
Selection that favors both extreme phenotypes over the middle average, which can split a population in two.
What is disruptive selection?
Speciation that occurs when biological populations become geographically isolated from one another.
What is allopatric speciation?
A postzygotic barrier where a hybrid grows into a healthy adult but cannot produce fertile offspring, like a mule.
What is hybrid sterility?
When two species directly influence each other's evolution over time, like flowers and their pollinators.
What is co-evolution?
A sharp drop in population size caused by a event like a natural disaster, which wipes out genetic diversity.
What is the bottleneck effect?
A condition in which an organism possesses more than two complete sets of chromosomes.
What is polyploidy?
A chain of neighboring populations where adjacent groups can mate, but the two ends of the chain cannot.
What is a ring species?
A postzygotic mechanism in which first-generation (F1) hybrids are viable and fertile, but their offspring (F2) are sterile or inviable
What is hybrid breakdown?
The pattern showing long periods of evolutionary stability interrupted by brief, rapid bursts of speciation.
What is punctuated equilibrium?