Evolution Flashcards
Hardy Weinberg Principles
Genetic drift, gene flow, mutation, natural selection, large population
Genetic Drift
Chance events that change allele frequencies (founder effect and bottleneck effect)
Gene Flow
Movement of individuals in and out of a population - changes gene frequencies by adding or moving out some alleles
Mutation
mutation creates variation by changing alleges- ex A to a
Natural Selection
Differential survival and reproduction rates
Large Population
Makes allele changes more/less reasonable (flipping a penny 10 times vs 100)
Prereproductive bariers
Geographic isolation - separated by physical barriers
Ecological isolation - different habitats prevent species from mating
Temporal isolation - mate in different seasons
Behavioral isolation - when a cerian behavior prevents species from mating, ex when bird songs don’t match
Mechanical isolation - physical differences prevent mating
Gametic Isolation - sperm cell chemically can’t enter egg cell
Post reproductive isolation
Prevent hybrids from becoming fertile adults
Reduced hybrid viability - f2 offspring are weaker
Reduced hybrid fertility - sterile offspring are produced
Hybrid breakdown - first generation hybrids are strong and offspring in next generation are weak
Speciation
Evolutionary processes through which new species arise
Allopathic Speciation
Comes out of geographic isolation
Sympatric Speciation
When species still live in the same area but a mutation stops them from breeding with their original species
Punctuated Equilibrium
No constant rate of speciation, it occurs in rapid bursts of change
Gradualism
Thought by Darwin and Lyell
Gradual divergence over long periods of time
Evidence for Evolution
Fossils, DNA similarities, embryology, homologous and analogues structures
Homologous structures
Existence of shared ancestry between structures in different species - ex wings in bats and arms of primates.
STRUCTURES ADAPTED TO DIFFERENT PURPOSES FROM THE SAME COMMON ANSCESTOR
Analogues structures
Structures that have the same function but different origins
Darwin and Natural selection
Organisms best fit for survival in a particular environment would be selected to live against those less suited for the environment
Comparing DNA variations
DNA variations can be used to compare where species branched off based on different mutations - ESPECIALLY IN MITOCHONDRIA
Hardy Weinberg equations
If none of the 5 agents for evolution happen, gene frequencies don’t change
p+q=1
p^2 + 2pq + q^2=1
Founder Effect
When a small group splinters and starts a new colony
Bottleneck effect
When a disaster or ecological change kills almost all of a species but a small group, which changes allele frequencies based on those that survive
Non random mating
Mating based on certain attractive characteristics
Reproductive isolation
Key to developing new species
Darwins principles
- Individuals vary in their chsracteristics
- Variations are inherited
- Many individuals don’t survive to adulthood
- Individuals who have more resources bc of their characteristics produce surviving offspring
