Evolution Part 1 Flashcards
what is artificial selection?
- Selectively selecting certain varieties of an organism over others via breeding programs
- Human beings selecting for traits while breeding animals (can be behavioural or physical traits)
- Ex. Pigeon breeding (for physical traits), crop breeding, fox breeding (for personality traits, which ended up leading to morphological changes and reproductive changes
proximal causes of morphological changes in Siberian foxes caused by artificial selection
- hormone & neurotransmitter changes
- Adrenal gland decreased, decreased cortisol (stress hormone) levels
natural selection
traits that confer the highest reproductive success increase in frequency over time
Darwin’s theory
- Darwin’s theory of natural selection: 1859; Mendel’s work on genetics: 1865-1866
- Darwin described his theory without even being aware of genetics
selective advantage
traits increases or decreases in frequency as a function of how well they suit organisms to their environment
fitness
- individual reproductive success; equal to the average contribution to the gene pool of the next generation that is made by individuals of the specified genotype/phenotype
- A fitness advantage of just 1% per generation is sufficient for one behaviour to replace another over evolutionary time
phenotype
observable properties of an organism
genotype
genetic makeup; results in phenotype
gene
Unit of heredity that is transferred from parent to offspring and is
held to determine some characteristic of the offspring
allele
Gene variant; one of two or more alternative forms of a gene
pre-reqs for natural selection
- variation in the trait
- fitness consequences of the trait
- mode of inheritance
- limited resources
- Ex. Rock mice example -> meets all pre-reqs for evolution (there’s a variation [colour of mice], it has fitness consequences (mice who can’t camouflage are eaten more frequently), it has mode of inheritance (can be passed down)
variation in the trait
- results in variation in behaviour, for example
- comes from mutations, recombination, and non-genetic changes
mutations
- change in genetic structures (ie. Addition/deletions)
- results in a variation in the trait
genetic recombination
- crossing over during cell division - “swapping” chromosome sections (random)
- results in variation in the trait
non-genetic changes
ex. Migration – new individuals introducing new trait variations
fitness consequences of the trait
- different varieties must have a differential impact on reproductive success
- ex. Male raven eggs -> males with different behaviours have different numbers of eggs with females
mode of inheritance
traits must be able to be passed on to the next generation (individual learning doesn’t usually cover this)
limited resources
some sort of pressure on the system that necessitates a change
environmental influences
- animals aren’t affected only by genotype/phenotype
- different environments have influence too
- ex. diet, location/climate, other species
example: mouse babies and alcohol
Alcohol effect on mouse babies are truly due to alcohol, not parenting (cross-fostering of control and experimental groups showed this)
