Evolution
Change in a population overtime
Natural Selection
The process by which organisms better adapted to their environment tend to survivie and produce more offspring
5 agents of evolutionary change
Natural Selection Genetic Drift Founder Effect Bottleneck Gene Flow Sexual Selection
Genetic Drift
A random change in allele frequencies in a population
Fixation
The reduction of genetic variation due to genetic drift
Founder Effect
Small number of individuals leave a population and become the founders of a new area - usually having a different allele frequency than the original population
Bottleneck
Reduction of a population (usually caused by death) leaving a small fraction of the original population intact, this smaller population will usually have different allele frequencies than those that died
Gene Flow
Migration into or out of a population will change allele frequencies
Sexual Selection
A form of natural selection that depends on an individuals ability to obtain a mate
Fitness
A measure of the relative amount of reproduction of an individual with a particular phenotype compared to the reproductive success of an individual with a different phenotype
3 important elements to an organisms fitness
Environment
Fitness measured relative to other genotypes or phenotypes in the population
Depends on an organisms reproductive success compared to the other organisms in the population
Stabilizing Selection
Individuals with intermediate phenotypes are most fit
Disruptive Selection
Individuals with extreme phenotypes experience the highest fitness, and those with intermediate phenotypes have the lowest
Species
Population that is capable of interbreeding to poduce healthy fertile offspring
Reproductive Barriers
Prezygotic and Postzygotic barriers
Prezygotic Barriers
Prevent mating between different species (this happens before the fusion of sperm and egg)
Temporal Isolation
Mating times differ (some like mornings, some like nights, etc)
Habitat Isolation
Living in different habitats that dont allow organisms to cross paths easily
Behavioral Isolation
No sexual attraction (you looking for a buff guy not a bitch like nik)
Mechanical Isolation
Wrong organs to fuck with (my nigga doesnt have a penis that goes into a vagina)
Gametic Isolation
Egg and sperm fail to fuse to make zygote
Postzygotic Barriers
Barriers that occur after the hybrid zygote is formed
Hybrid Sterility
The hybrid cannot reproduce
Mechanisms of Speciation
Making a new species
Altruistic Behavior
Behaviors that come at a cost to the individual doing the behavior while benefiting the recipient (jumping infront of a bullet to save someones life)
Female investment to reproduction
Produces larger gamete (egg) (by making larger gamete, the female has already invested more towards reproduction because this takes more energy to do)
Male investment to reproduction
Produces the smaller, usually mobile gamete
Tactics for getting a mate
Courtship rituals
Gifts
Control resources
Looks
Tactics for keeping a mate
If the offspring benefit from having a father, the male is more likely to provide parental care
Mate Gaurding
Copulatory plugs-break off penis into her so no other penis can get in
Monogamy
One male one female
Polygyny
1 male bunch of females
Polyandry
1 female and bunch of males
Sexual Dimophism
Differences between male and female (size, aggressiveness)
Sexual Monomorphism
Male and females look the same
Ecology Levels
Individual Population Community Ecosystems Biosphere
Individual
Organism
Population
A group of individuals of the same species living in a defined area
Community
Consists of two or more populations of diff species living in the same area
Ecosystems
Consists of a community of living things interacting with the physical aspects if their environment
Biotic Factors
Living things in an ecosystem
Abiotic Factors
Nonliving things in an ecosystem
Biosphere
Consists of all the earths ecosystems containing living species
Limitations for species to live
Physical factors
Interactions with other species
Geographical barriers
Interactions between species
Competition Predation Parasitism Commensalism Mutualism
Competition
Two species competing for resources
Competitive exclusion
When one species wins the competition with another species excluding it
Predation
Predators seek prey to survive
Parasitism
One species benefits at the expense of another (without killing it for as long as possible)
Commensalism
One species benefits but the other is unharmed
Mutualism
Both benefit from the interaction
Genetic Biodiversity
The collection of genes within a population
Causes of biodiversity loss
Habitat destruction Invasive species Overharvesting Pollution Climate change
Population growth
Most species cannot handle expionential growth
Density dependent
Events that depend on a population size to occue
Density independent
Events that dont depend on the population of a species to occur