Download 8.0-Other Mechanisms of Evolution

yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Human evolutionary genetics wikipedia, lookup

Adaptive evolution in the human genome wikipedia, lookup

Heritability of IQ wikipedia, lookup

Genetics and archaeogenetics of South Asia wikipedia, lookup

Genome (book) wikipedia, lookup

Sociobiology wikipedia, lookup

Race and health wikipedia, lookup

Genetic history of North Africa wikipedia, lookup

Race and genetics wikipedia, lookup

Human genetic clustering wikipedia, lookup

Human genetic variation wikipedia, lookup

Other Mechanisms of Evolution
Natural selection is not the only mechanism through
which populations evolve.
Other Mechanisms of Evolution
Gene flow
• Definition: Movement of
alleles from one
population to another
• How it works: When
animals move from one
population to another &
breed in the new
population; when spores
or seeds of plants or
fungi are spread to new
bald eagle migration
Other Mechanisms of Evolution
Gene flow:
• Lots of gene flow
between populations
Results in
• Lots of gene flow
Results in
between populations
Similar populations
Different populations
(genetically) that could
evolve into different
Other Mechanisms of Evolution
Genetic drift
• Definition: Changes in allele frequencies due to chance
• How it works: Small populations are more likely to be
affected by chance; Due to chance some alleles may
increase in frequency while others may decrease & even
become eliminated from the population
Other Mechanisms of Evolution
Genetic drift
• Key Terms
– Bottleneck effect: Genetic
drift that occurs after an
event drastically reduces the
size of a population
– Founder effect: Genetic drift
that occurs after a small
number of individuals
colonize a new area
• Negative effects: Population loses genetic variation, so
population is less likely to have some individuals that will be
able to adapt to a changing environment; harmful alleles
may become more common due to chance alone
Other Mechanisms of Evolution
Sexual selection
• Definition: Process in which
certain traits increase mating
success & therefore become
more common in the population.
• How it works: Females
preferentially mate with males
that display certain traits, so
those traits get passed onto
offspring & can become more
exaggerated each generation
Other Mechanisms of Evolution
Sexual selection
• Types
– Intrasexual: Competition/fighting
among males for females
– Intersexual: Males display certain
traits to attract females