6b Flashcards
Evolution
change in heritable characteristics of biological populations over successive generations.
types of fossils
nesting, faeces, bones, footprints and skin impression
List the four postulates regarding populations proposed by Darwin and Wallace’s theory of evolution by natural selection
Genetic variation
Genetics are passed to offspring
Death of some
Survival and reproduction are not determined by chance but depends at least in part on heritable characteristics
Define homologous structures
structures that are similar these show that there is a common ancestor.
Define vestigial structures
Structure which no longer perform the function of which they originally evolved to do in the species ancestor
Define Analogous structure
Non - homologous structures which serve similar functions evolved from convergent evolution as such they resemble each other. Consider birds and bees
evidence for the last universal ansestor (LUCA)
By analysing biochemical and genetics (DNA barcoding is visual similarities of DNA coding) we are able to note similarities that may be genetically connected and traits which may have evolved due to environmental conditions.
artificial selection examples
Wild mustard plant has variated into kale, broccoli, cabbage and cauliflower
Cows bos indicus and bos taurus divided by north and south.
Natural selection example are insect becoming resistant to insecticides and the peppered moth darkening after the industrial revolution
Define gene pool
A set that contains all of the alleles of all of the genes from all of the individuals in a population.
Hardy-Weinberg principle
Population geneticists use the term equilibrium population for the hypothetical non-evolving population in which allele frequencies do not change as long as the following conditions are met.
There must be no mutation
There must be no gene flow
The populations must be very large
All matings must be random with not endency for certain genotypes
There must be no natural selection. That is, all genotypes must reproduce with equal success.
gene flow
the movement of all alleles in or out of the population caused by migration or immigration.
population bottleneck
A drastic size reduction in a population that results in less genetic variation
Founder effect
Founder effect - few individual become isolated from the main population and this results in divergent evolution
genetic drift
‘drift in equilibrium’ shift in gene frequencies
define sexual selection
A special kind of selection that acts on traits that help an animal acquire a mate. (peacocks)
