Evolution Flashcards
Adaptive Radiation
a process in which organisms diversify rapidly into a multitude of new forms, particularly when a change in the environment makes ew resources available, creates new challenges, and opens environmental niches
Allele
A variant form of a gene (diploid organisms have 2 alleles per genetic locus)
Allopatric Speciation
A population forms a new species because of geographic isolation from parent population
Analogous Structures
Structures in different animals that appear similar yet are anatomically different, with different functions
Antibiotic Resistance
Occurs when bacteria change in some way that reduces or eliminates the effectiveness of drugs, chemicals, or other agents designed to cure or prevent infections
Artificial Selection
The process by which species are modified by humans (i.e. selective breeding of dogs)
Bottleneck Effect
a sudden change in environment drastically reduces the size of a population (gene pool of survivors may not reflect the old population)
Adaptation
A change in an organism in response to its environment which increases its chance of survival (inherited and passed along generations; do not occur quickly)
Cladogram
A diagram to show relations among organisms
Clade
A life-form group consisting of an ancestor and all its descendants—representing a single “branch” on the “tree of life”. The ancestor may be an individual, a population or even a species (extinct or extant).
Convergent Evolution
explains why distantly related species can resemble one another; two organisms develop similarities as they adapt to similar environmental challenges, NOT due to common ancestry. (resulting likeness is analogous)
Directional Selection
shifts overall makeup of population (phenotype); favors one extreme
Disruptive Selection
spreads out population; favors both extremes
Divergent Evolution
The accumulation of differences between groups which can lead to the formation of new (different) species; often result of diffusion of same species which blocks gene flow and allows differentiation of characteristics
Evolution
Change in species over time
Founder Effect
A few individuals become isolated from a larger population and establish a new population whose gene pool is not reflective of the source population
Gene Flow
occurs when a population gains or loses alleles by genetic additions or subtractions; reduces genetic difference/population becomes more similar
Genetic Drift
unpredictable fluctuation in allele frequencies from one generation to the next; smaller populations are more likely to be affected
Homologous Structures
Anatomical signs of evolution; suggest common ancestor
Prezygotic Barriers
prevent mating or hinder fertilization; isolation- habitat, behavioral, temporal (timing), mechanical (anatomical), gametic (gametes won’t fuse)
Postzygotic Barriers
Prevent fertilized egg from developing into fertile adult; reduced hybrid viability (incompatibility ceases development), fertility (offspring is sterile), hybrid breakdown (offspring can reproduce but their offspring are sterile)
Natural Selection
heritable traits become more or less in a population as a function of the effect of inherited traits on the differential reproductive success of organisms interacting with their environment
Outgroup
a group of organisms that serve as a reference group when determining the evolutionary relationship among three or more groups of organisms
Phylogenetic Tree
a branched diagram showing the inferred evolutionary relationships among various biological species or beings
