Speciation & Evolution Misconceptions

allopatric speciation

speciation that occurs via geographic separation

allopatry

occurring in different geographic areas

behavioral isolation

type of reproductive isolation that occurs when a specific behavior or lack of one prevents reproduction from taking place

biological species concept

species concept based on reproductive isolation

dispersal

movement of individuals to a new geographic area

fusion

upon reconnection, reproductive barriers weaken and the two lineages become one

gametic isolation

type of reproductive isolation that occurs when differences in gametic cells (egg and sperm) prevent successful fertilization

habitat isolation

reproductive isolation resulting when species' populations move or are moved to a new habitat, taking up residence in a place that no longer overlaps with the same species' other populations

hybrid

offspring of two closely related individuals, not of the same species

hybrid inviability

type of reproductive isolation that occurs when hybrids do not survive to sexual maturity

hybrid sterility

type of reproductive isolation that occurs when hybrids are viable but biologically or ecologically sterile

hybrid zone

area where two closely related species continue to interact and reproduce, forming hybrids

mechanical isolation

type of reproductive isolation that occurs when differences in the size or shape of reproductive organs makes successful mating impossible

migration (gene flow)

transfer of alleles from one population to another, makes populations more similar

monophyletic group (clade)

a group that consists of one ancestor and all of its descendants

morphological species concept

species concept based on differences in size, shape, or other morphological attributes

phylogenetic species concept

species concept based on identifying smallest sets of monophyletic groups in a phylogeny

phylogeny (phylogenetic tree)

representation of the evolutionary relationships among organisms

postzygotic barrier

reproductive isolation mechanism that occurs after zygote formation

prezygotic barrier

reproductive isolation mechanism that occurs before zygote formation

reinforcement

continued speciation divergence between two related species due to low fitness of hybrids between them

reproductive isolation

situation that occurs when a species is reproductively independent from other species; behavior, location, or reproductive barriers may cause this to happen

speciation

formation of a new species

species

group of populations that interbreed and produce fertile offspring

species concept

a set of criteria used to define and differentiate species

temporal isolation

differences in breeding schedules that can act as a form of prezygotic barrier leading to reproductive isolation

vicariance

the physical splitting of a population into smaller, isolated populations by a physical barrier

population genetics

study of how selective forces change the allele frequencies in a population over time

gene pool

all the alleles that the individuals in the population carry