Patterns of Evolution, Reproductive Isolation, Speciation, Genetic Drift Flashcards
Unrelated species that form an inter-relationship can undergo
coevolution
Unrelated species that are in similar environments can undergo
convergent evolution
Unrelated species under intense environmental pressure can undergo
extinction
Related species under intense environmental pressure can undergo (2)
extinction
punctuated equilibrium
Related species in small populations can undergo
punctuated equilibrium
Related species in different environments can undergo
adaptive radiation
Three types of reproductive isolation
Behavioral, geographical, and temporal
Behavioral isolation
difference in mating rituals (calls, dances, etc.)
Geographical isolation
difference in location, separated by landscape (mountains, rivers, oceans, canyons, etc.)
Temporal isolation
difference in mating time (different time of day/year, different seasons)
What are the two causes of speciation?
Isolation and genetic divergence
What is isolation? (effects, causes)
- limits gene flow
- either physical barrier or differing conditions
- only considered different species once enough genetic variation occurs
What is genetic divergence? (crossing into speciation, probability)
One species splitting into several different species rapidly
1. enough genetic differences to prevent interbreeding
2. more likely in small populations
3. like genetic drift
Result of speciation
Two groups of individuals more closely adapted to the local environment than the other group. There may not always be an increase in fitness, but natural selection will eventually.
What is genetic drift?
random changes in allele frequencies in small populations
What is the Bottleneck Effect?
Great reduction in population.
Changes gene pool.
Can cause genetic drift.
Main concern for endangered species
What is a bottleneck event?
A random but major catastrophe that greatly reduces population size
What is the Founder Effect?
A small group breaks off from the main population and colonizes a distant area.
Limited diversity
Results in quick divergence (adaptive radiation) to fill all available niches
Coevolution
organisms evolving as a result of the other (pollinators and plants)
Convergent Evolution
evolution producing similar features in unrelated species (emus and ostriches)
Punctuated Equilibrium
rapid evolution after a period of slow evolution (after migration, mass extinction leaving many niches open)
Adaptive Radiation/Divergent Evolution
one species rapidly evolves into several species living in different ways (Darwin’s finches)
