Adaptation and Evolution Flashcards
(30 cards)
What is evolution?
Change in allele (or gene) frequencies within a gene pool over time which can lead to speciation
What did Darwin observe on the Galapagos islands?
Finches on the islands resemble mainland finches (common ancestor)
Species on the archipelago differed in beak size and form (evolved)
What did Darwin conclude about evolution?
That natural selection could be a driving force
What is an allele?
Different forms of a gene
What is a gene pool?
The sum total of all of the alleles in a population
What is a phenotype?
An attribute of an organism such as behaviour, morphology, or physiology
What is a genotype?
The set of genes an organism carries
What does evolution require?
Phenotypic variation that is heritable
What is phenotypic plasticity?
Variation as a result of environmental influences
What are genetic differences?
Variation as a result of differences in the genome
What is phenotypic variation a function of?
Genetic variation and environmental effects
Vp=Vg+Ve
What does h^2 (heritability) equal?
Vg/Vp or Vg/(Vg+Ve)
What is the Hardy-Weinberg principle?
In an infinitely large population, where mating is random and evolutionary forces absent, allele frequencies will remain constant across generations
What is genetic drift?
In populations that are not infinitely large, allele frequencies will naturally fluctuate due to chance
In small populations, the effect of genetic drift is more pronounced, can lead to a population losing an allele
What is bottleneck genetic drift?
A reduction in genetic diversity in a population due to a large reduction in population size
What is the founder effect genetic drift?
A small number of individuals leave a large population to colonize a new area and bring with them only a small amount of genetic variation
What drives evolution?
Natural selection
What is the theory of natural selection?
Many offspring are produced, not all survive
Traits vary among individuals within a population and may be heritable
Some heritable traits give individuals an advantage
Advantageous traits become more common
What happened to beak sizes on the Galapagos during a drought?
Drought caused a decline in seed abundance and an increase in seed hardiness
Killed finches with medium beaks but birds with large beak thrived
What is directional selection?
Extreme phenotypes are favoured
What is stabilizing selection?
Average phenotypes are favoured
What is disruptive selection?
Two or more extreme phenotypes are favoured
What is adaptation?
Traits that have been selected for through natural selection
What is speciation?
Physical and ecological processes interact with selection and random processes to produce new species
