Chapter 4 Flashcards
Population
Cluster of individuals of the same species who share a common geographical area and find their mates more often in their own cluster than in others
Gene Pool
All the alleles within a population
Four Core Processes of Evolution
Mutation, Gene Flow, Genetic Drift, and Natural Selectoin
Mutation (know the various types)
changes ot the nucleotide sequence in the DNA
- the ultimate source of new variation in DNA
- Completely random
- must examine at the level of a population (for evolutionary importance)
Gene Flow
The movement of alleles within and between populations
INCREASES variation within populations
DECREASES variation between populations
Migration
Movement of alleles in and out of populations
Nonrandom Mating
Pattern of mating in which individuals mate preferentially with certain others
Assortative Mating
Mate slection based on similarity (positive assortative) or differences (negative assortative) in traits
Genetic Drift
-Random factors cause fluctuation in allele frequencies across generations
-Reduces variation in a pop. (to fixed point)
-greatest effect in small populations
DECREASES variation within populations
INCREASES variation between populations
Founder Effect
the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.
Bottleneck Effect
A dramatic reduction in the size of a population such that the genetic diversity in the population is substantially curtailed
- Losing genes in the gene pool due to the removal of individuals
- makes it easier for an allele to reach fixed frequency
- type of genetic drift
Exaptation
Trait that is currently serving a function other than that for which it orginally arose
Epigenetic system
The factors in the body that work in combination with the genes and proteins to affect phenotypes
Behavorial inheritance system
The system of imitation and learning by which behavior passes from generation to generation
Symbolic inheritance
The passing down of knowledge via symbols and language
Developmental Systems Theory (DST)
An approach that includes the development of biological and behavorial systems as a core part of evolutionary processes
Niche Construction Theory
The modification of niches by organisms and the mutual interactions between organisms and environments
-Organisms alter feature of the habitat making it better or worse=>As conditions change, natural selection operates on the phenotype=>Natural selection alters frequencies of genotypes/alleles
Biological Species
A group of interbreeding natural populations that are reproductively isolated from other such groups
-individuals can breed together and not with other species
Paleospecies
Species defined on the basis of fossil evidence
- Cannot observe whether or not they can breed with a certain species
- form, time period, geographical area, habitats
Allopatric Speciation
Mode of speciation that involves a separation and isolation of populations of the parent species
-Occurs when geographic barrier seperates parts of a population
Phyletic Gradualism (Darwinian Evolution)
The slow accumulation of small changes in populations such that over time enough change has occurred to result in a speciation event
Punctuated Equilibrium
Rapid biological changes in organisms followed by long, relatively static periods during which little biological change occurs
Homology/Parallel Evolution
Type of evolutionary process whereby species come to share phenotypic characteristics due to recent common ancestry
Homoplasy/Convergent Evolution
Type of evolutionary process whereby species come to share phenotypic characteristics due to similiar environmental pressures
-due to independent evolution
Fertility
Actual reproduction (# of offpsring produced)
Fecundity
Potential for reproduction (problem w/Neandrathals)
Population Genetics
Concerned with:
- the distribution of alleles within a population
- the variation in alleles between populations
- the variation in alleles in populations over time
Breeding Population
A group of organisms that chooses mates within thay group
Hardy-Weinberg Equation
A way to predict the number of expected genotypes in the offspring population based on the observed allele frequencies in the parental population.
-Predicts equilibrium between generations if certain assumptions are met
Consanguinous Mating (inbreeding)
Mating with relatives
- increases the frequency of homozygotes but does not change the allele frequencies
- big effects when alleles are rare (recessive diseases)
Sexual Selection
Preferences in (assortive) mating that increase the frequency of some allele combinations in the next generation
Mutation (know the various types)
- the ultimate source of new variation in DNA
- Completely random
- must examine at the level of a population (for evolutionary importance)
Stabilizing Natural Selection
Favors variation in the middle of the distribution
Directional Natural Selection
Selection that favors variation toward one of the extremes of the distribution
Disruptive Natural Selection
Favors variation at both ends of the disribution
Balanced Polymorphism
A situation in which two different versions of a gene are maintained in a population of organisms because individuals carrying both versions are better able to survive than those who have two copies of either version alone.
Subspecies
A species with two or more divisions that have little to no gene flow between them
-takes thousands of years
Macroevolution
The origin and evolution of species
Speciation
The formation of new and distinct species in the course of evolution
-Due to reproductive isolation
Anagenesis
Species evolve gradually from one species into another
Cladogenesis
One or more species branch off from an original species
Adaptive Radiation
Periods when speciation results in several new, but closely related, species that are more or less contemporary in time
-b/c of expansion into new environments
Mass Extinction
When a large number of species become extinct at more or less the same time
Cladistics
Classification based soley on shared derived traits to create evolutionary trees
