D4.1 Natural Selection Flashcards
(21 cards)
Evolution
Cumulative change in heritable characteristics over a period of time
Natural selection
Process that drives evolutionary change
Process of natural selection
- Overproduction of offspring
- Variation within population (result of meiosis, sexual reproduction, mutations)
- Struggle for survival (not enough resources)
- Differential survival
- Reproduction
Sources of variation in a species
Mutations, meiosis, sexual reproduction
Gene
Heritable factor that consists of a length of DNA and influences a specific characteristic
Allele
Alternative versions of a gene
Mutation
Change to base sequence of DNA
Fitness
How well adapted an organism is to its environment
Differential survival
Varying chances of survival and reproduction among a population
Sexual selection
Reproductive success of an individual
Sexual dimorphism
Morphological differences between male and female in a species
Allele frequency
Proportion of a particular allele in a population
Phenotype
Set of observable characteristics of an individual
Genotype
Organism’s combination of alleles an individual has for a particular trait or gene
Directional selection
One extreme phenotype favored over others
Disruptive selection
Two extreme phenotypes are favored over one intermediate phenotype
Stabilizing selection
One intermediate phenotype is favored over extreme phenotypes
Hardy Weinberg conditions for genetic equilibrium
- No new alleles are generated by mutation
- Organisms mate randomly
- Individual or gametes don’t enter/exit population
- Large population
- No natural selection
Artificial selection
Selective breeding of plants and animals based on specific traits chosen by humans
Artificial selection steps
- Desirable traits selected
- Individuals with better version of trait chosen to reproduce
- Repeated for each successive generation
