Studied by 52 PeopleOrganic Evolution
Tags & Description
Organic Evolution
Population change overtime.
Natural Selection
Theoretical process by which gene variation and the environment lead to significant changes in a population because individuals with gene variations more suited to the environment survive longer and reproduce more.
Theory of Inheritance
the theory that organisms develop new traits as needs arise and pass these acquired traits down to their offspring (wrong) (Lamarck)
Adaptive radiation
the formation of a new species from an ancestral species caused by the availability of a new habitat.
Adaptation
occurs when an inheritable phenotype increases the likelihood of an animal to survive and successfully reproduce.
Fitness
a measure of the capacity for successful reproduction in a given environment compared to other of the same species.
Microevolution
a change in the frequency of alleles in population over time.
Macroevolution
Large-scale changes that result in an extinction or formation of a new species
Biogeography
the study of the geographic distribution of plants and animals.
Paleontology
the study of the fossil record.
Fossils
evidence of plants and animals from the past that has become a part of the earth's crust.
Convergent Evolution
When unrelated species have similar adaptations (Analogous)
Analogous Structures
Similar structures due to convergent evolution.
Homologous Structures
Similar structures due to shared ancestry.
Comparative Anatomy
The study of structural similarities in living or fossilized animals and homologies that show evolutionary relationships.
Homeotic Genes
Determine identity of body regions in early embryos.
Phylogeny
refers to evolutionary relationships among species.
Phylogenic Tree
shows lines of descent from an ancestral species to modern descendants.
Nodes
represent individuals, populations or species.
Branches
represent evolutionary connection between nodes.
Population
groups of individuals of the same species that occupy a given area at the same time and share a common gene pool.
Gene pool
the sum of all the alleles for all traits in a sexually reproducing population.
Population Genetics
the study of the genetic events in gene pools.
Hardy-Wienberg Theorem
States that mixing of alleles in meiosis and their recombination don't alter allele frequencies across generations, given several factors.
large population
Random sexual reproduction
no migration
no mutation
no natural selection
Genetic Drift
Chance events effecting gene frequencies in a population (Neutral evolution)
Founder Effect
a type of genetic drift caused by the separtation of a few individuals from a bigger population, creating their own population. They do not carry the same gene frequencies as the larger population so this new population will likely have less genetic variation.
Bottleneck Effect
A form of genetic drift that takes place when an event dramatically decreases the size of a population resulting in decreased genetic variation even as populations regrow.
Gene Flow
Changes in gene frequency caused by immigration or emigration of individuals.
Mutation Pressure
a measure of the tendency of gene frequencies to change through mutation.
Selection Pressure
the tendency for natural selection to occur
Directional selection
occurs when individuals with one phenotypic extreme are at a disadvantage compared to all others causing a decrease in that extreme.
Disruptive Selection
Occurs when both phenotypic extremes are at an advantage to those with the intermediate phenotype.
Stabilizing Selection
Occurs when both phenotypic extremes are at a disadvantage and leads to a decrease in phenotypic range.
Balanced Polymorphism
occurs when different phenotypes are maintained at relatively stable frequencies.
Species
a group of populations in which genes are actually or potentially exchanged through interbreeding.
Speciation
The formation of a new species.
Reproductive isolation
when populations cannot reproduce with one another
Premating isolation
prevents mating altogether, via impenetrable barrier or changes in courtship behavior.
Postmating Isolation
prevents successful fertilization.
Allopatric Speciation
Occurs when subpopulations become geographically isolated.
Demes
Small local populations, not isolated.
Parapatric Speciation
relative isolation of a deme can make its members experience different selection pressures that can ultimately result in speciation. (No certain cases)
Sympatric Speciation
Occurs within one population when individuals become reproductively isolated.
Phyletic gradualism
evolution occurs gradually over millions of years.
punctuated equilibrium
long periods of stasis interrupted by brief periods of change.
Mosaic Evolution
occurrence within a population of different rates of evolution in various structures or functions.
Systemics
study of evolutionary relationships among and diversity of organisms. (Taxonomy)
Nomenclature
Assignment of distinctive names to each species.
Taxon
any grouping of animals that share a particular set of characteristics.