Patterns in evolution Flashcards
(19 cards)
Factors that can influence natural selection
Diseases
Climate conditions
Food availability
Predators
Directional Selection
selection that favours an increase or decrease in the value of a trait from the current population average
Stabilizing Selection
selection against individuals exhibiting traits that deviate from the current population average
Disruptive Selection
selection that favours two or more variations of a trait differ from the current population average
Sexual Selection
reproductive success caused by variation in the ability to obtain mates; results in sexual dimorphism and mating and courtship behaviours
Genetic Drift:
changes to gene populations as a result of chance, not selection
Genetic Bottlenecks
a dramatic, often temporary, reduction in population size usually resulting in significant genetic drift
Founder Effect
genetic drift that results when a small number of individuals separate from their original population and establish a new population
Often leads to adaptive radiation, the rapid evolution of one species into several species, each adapted to a new niche.
Speciation
when one species splits into two or more new species that cant breed
Species:
Share the same gene pool and there is interbreeding
New species can evolve under a variety of circumstances:
Reproductive Isolation
Allopatric Speciation
Sympatric Speciation
Reproductive isolating mechanism:
Any behavioural, structural, or biochemical trait that prevents individuals of different species from reproducing successfully together
Can be Prezygotic or Postzygotic
Prezygotic
prevents interspecies mating and fertilization
mechanisms:
Behavioural
Temporal
Ecological
Mechanical
Gametic
Zygotic mortality
Hybrid inviability
Hybrid infertility
Allopatric Speciation
Is the formation of a new species as a result of evolutionary changes following a period of geographic isolation
Sympatric Speciation
Is the evolution of populations within the same geographic area into separate species
Human action can be a pressure that causes this to occur
Divergent Evolution
is the evolution of many species from a single common ancestor.
Adaptive radiation
is a type of divergent evolution
a single species is rapidly evolved into many new distinct, but closely related species.
Convergent Evolution:
the evolution of similar traits in distantly related species
Coevolution:
one species evolves in response to the evolution of another species
