notes Flashcards
biological evolution
- Descent with modification
- 1 way to detect evolution is to look for a shift in the gene pool of a population
- Allele frequencies change from one generation to the next when evolution occurs
Microevolution
- Small scale genetic changes within a species
- Over long term
- Microevolutionary changes also explain macroevolutionary events
- Emergence of new species
catastrophism
- Continual remodeling of Earth’s surface
- Some people explained the distribution of rock strata with the idea
Principle of superposition
- Lower rock strata are older than those above
- Suggests an evolutionary sequence for fossils within them
Lamark
1st to purpose a testable mechanism of evolution, but it was based on use and disuse of traits during an organism’s lifetime
survival of the fittest
organisms with highest evolutionary fitness are the ones that have the greatest reproductive success
fitness
an organisms contribution to the next generation’s gene pool
Does evolution occur if a population meets all of Hardy-Weinburgs assumtions?
NO, because allele frequencies do not change from generation to generation
Hardy-Weinberg in real world
conditions for Hardy weinberg equation do not happen in natural populations
Directional Selection
1 extreme phenotype becomes more prevalent in a population
Disruptive selection
Multiple extreme phenotypes survive at the expense of intermediate forms
Stabilizing selection
An intermediate phenotype has an advantage over individuals with extreme phenotypes
Balanced Polymorphism
- Natural selection indefinitely maintains more than two alleles for a gene
- Harmful recessive alleles may remain in a population because of a heterozygous advantage in which carriers have a reproductive advantage over homozygous
sexual dimorphisms
-Differentiate sex
-Result from sexual selection
(lions–males have manes, females don’t)
Sexual selection
Natural selection in which inherited traits, even those that seem nonadaptive, make an individual more likely to mate
INTRAsexual selection
competition that does not involve a choice by the opposite sex
INTERsexual selction
Reflects mate choice by members of the opposite sex
Do most mutations pass on to the next generation?
Most mutations do NOT pass to the next generation
Genetic Drift
- occurs by chance
- allele frequencies change purely by chance events, especially in small populations
- Founder effect and Bottlenecks are examples of genetic drift
Nonrandom Mating
- concentrates alleles locally
- Causes some alleles to concentrate in subpopulations
gene flow
- moves alleles between populations
- allele movement between populations through things like migration
Factors that cause EVOLUTION (5)
- Natural Selection
- Mutation
- Genetic drift
- Nonrandom Mating
- Gene Flow
Natural Selection
- selects for adaptations that maximize reproductive success
- Individuals vary for inherited traits (variation)
- Many more offspring are born than to survive (overproduction)
- Life is a struggle to acquire limited resources (selection)
- Environment eliminates poorly adapted individuals (adaptation)
Origin of Species
- theory that proposed natural selection as an evolutionary mechanism
- Charles Darwin
artificial selection
-like natural selection except humans take place of environment
Modern evolutionary synthesis
unifies ideas about DNA, mutations, inheritance, and natural selection
Natural selection requires…
VARIATION which arises from random mutatuons
Hardy-Weinberg equilibrium
Assumes no factors of evolution occur
