Evolution Flashcards
Microevolution
Change in allele frequencies in populations over time
Macroevolution
Major evolutionary change
Stabilizing Selection
Selects for common phenotype
Directional Selection
Favours a trait at one extreme
Disruptive Selection
Favours two extremes. Selects against common phenotype
Sexual Selection
Preference of characteristics by one sex in individuals of the other sex
Artificial selection
Selection by humans. Not natural. (dog breeding)
Sources of variation
Mutations, meiosis, diploidy, outbreeding, polymorphism (heterozygote advantage)
Frequency dependent selection
Selects for the least common phenotype
Hybrid vigour
A heterozygous hybrid offspring is more advantageous than its homozygous parents
Gene flow
Due to the flow of individuals in and out of populations. Individuals can enter or leave populations, carrying alleles with them.
Genetic Drift
Random changes in alleles
Founder Effect
A group migrates to a new place.
Bottleneck Effect
A population is suddenly decreased in size due to a natural disaster, etc.
HW Equation
p^2+2pq+q^2=1
HW Assumptions
No evolution: No natural selection No mutation No gene flow No genetic drift Random mating
Divergent Evolution
Evolution from a common ancestor. Results in homologous structures
Convergent Evolution
Two species exhibit similar traits despite sharing no common ancestor. Exhibit analogous structures
Parallel Evolution
Two species diverge from a single common ancestor and then evolve in similar ways
Coevolution
Both predator and prey evolve
Macroevolution: Phyletic Gradualism
Gradual small-changes : evolution
Macroevolution: Punctuated EQ
Long period of no evolution interspersed with short period of rapid evolution
Types of prezygotic reproductive barriers
Habitat, temporal, behavioural, mechanical, gametic
Types of post zygotic reproductive barriers
Hybrid inviability (zygote doesn't properly develop) Hybrid sterility (hybrid can't reproduce) Hybrid breakdown (hybrid has reduced fertility)
Allopatric Speciation
A geographic barrier results in the divergence of two species
Sympatric Speciation
Formation of new species without a geographic barrier
Types of Clades
Paraphyletic, Monophyletic, Polyphyletic
Polytomy
A branch on a cladistics tree that has three or more species coming off of it. Don’t have enough information to determine exact times of speciation.
Ecology
Relation of organisms to each other and their surroundings
Population
Group of individuals of the same species living in the same area
Community
Group of populations living in the same area
Ecosystem
A community of interacting organisms and their environment
Biosphere
Any region of the world with living organisms
Habitat
Place where a certain organism usually lives
Types of dispersion patterns
Clumped, uniform, random
Population size
Number of individuals within population
Population density
Number of individuals per unit of area or volume
Age Structure
Describes the age of individuals of a population
Survivorship Curve Types
Type I (higher rate of death among old: ex humans) Type II (constant mortality rate throughout the lifecycle of an organism. ex squirrels) Type III (high mortality rate among young members of population)
Biotic Potential
Max growth rate of a species under perfectly ideal conditions
Carrying capacity
Max number of individuals of a population that can be supported by their habitat
Density Dependent limiting factors
Act as population is large in size
Density independent limiting factors
Act regardless of population size (example: natural disasters)
Intrinsic Rate of Growth
Maximum growth rate of a population
Exponential Growth
Occurs when there is more reproduction than mortality in a population
Logistic Growth
Occurs when there is a carrying capacity (K) acting on a population
Types of animal behaviour
Innate and Learned
Innate animal behaviour
Molded by evolution. These behaviours increase the fitness of the animal.
Learned animal behaviour
Behaviours acquired by experiences/environment
Instinct
Inherited (genetic) behaviour. Example: in mammals, mother cares for children
Fixed action pattern
Inherited behaviour by animals due to a sign stimulus
Imprinted behaviour
A behaviour is “imprinted” on an animal during a specific phase in their lifetime, and in that phase ONLY (ex. salmon return to their birthplace to mate. their birthplace is thus imprinted on them at their birth)
Associated Learning
when an animal learns that two or more events are connected/associated
Classical conditioning
When an animal is conditioned to respond to substitute stimulus, as opposed to normal stimulus (see Nicole’s notes)
Trial and Error (Operant Conditioning) learning
Animal connects its behaviour to a sort of response it receives
Spatial Learning
An animal connects to a specific location
Habituation
Learned behaviour that allows an animal to disregard meaningless stimuli
Observational Learning
When an animal observes and copies another animal’s behaviour
Insight
An animal learns a new behaviour that will have a positive outcome
Types of animal movement
Kinesis, taxis, migration
Kinesis
Undirected movement in response to a stimuli
Taxis
Directed movement in response to a stimuli
Migration
Long distance, seasonal movement by animals
Types of animal communication
Chemical, audial, visual, tactile
Chemical communication
Animals use pheromones to communicate chemically
Releaser pheromones
Chemicals that cause immediate and specific changes in behaviour
Primer pheromones
Cause physiological changes
Foraging behaviours
Animals want to maximize feeding while using minimal energy to obtain food. They will pack together and associate certain colours with foods to achieve this.
Agonistic behaviour
Aggression and hostile behaviours. Comes from competition for food.
Dominance hierarchies
Hierarchies established within population limits competition for food and mates.
Territoriality
Animals defend their territory
Altruistic Behaviour
When animals risk their safety to protect other animals. Increases fitness of animal and their relatives.
Kin selection
Favours reproductive success of an animals relative’s, even at cost to the animal’s own reproductive success and safety
