BIO 1220 Chapter 24 Vocabulary

allopatric speciation

The formation of new species in populations that are geographically isolated from one another.

allopatry

populations that are geographically separated

allopolyploidy

polyploidy resulting from contribution of chromosomes from two or more species

autopolyploidy

an individual that has more than two chromosome sets that are all derived from a single species

backcrossing

crossing of a hybrid with one of its parents or an individual genetically similar to its parent, in order to achieve offspring with a genetic identity which is closer to that of the parent

behavioral isolation

isolation between populations due to differences in courtship or mating behavior

biogeography

Geographic distribution of species.

biological species concept

Definition of a species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but are not able to produce viable, fertile offspring with members of other populations.

clade

A taxonomic grouping that includes only a single ancestor and all of its descendants.

colonization

the spread and development of an organism in a new locality or habitat

common ancestry

a group of organisms share common descent if they have a common ancestor

cryptic species

a species that cannot be distinguished from similar species by easily identifiable morphological traits

disruptive selection

form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle

fusion (of populations)

the two populations freely interbreed

gametic barrier

matings fail because eggs and sperm are incompatible

genetic divergence

refers to fixed genetic differences between species

genetic isolation

barrier to gene flow isolates populations

habitat isolation

populations live in different habitats and do not meet

hybrid sterility

hybrid offspring mature but are sterile as adults

hybrid viability

hybrid offspring do not develop normally and die as embryos

hybrid zone

a geographic region in which members of different species meet and mate, producing at least some offspring of mixed ancestry

hybridization

Breeding technique that involves crossing dissimilar individuals to bring together the best traits of both organisms

mechanical isolation

Morphological differences prevent fertilization.

monophyletic group

includes a single common ancestor and all of its descendants

morphology

study of form

morphospecies concept

The definition of a species as a population or group of populations that have measurably different anatomical features from other groups.

nondisjunction

Error in meiosis in which homologous chromosomes fail to separate.

phylogenetic species concept

defines a species as the smallest group of individuals that share a common ancestor

phylogenetic tree

A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms.

phylogeny

Evolutionary history of a species

polyploidy

condition in which an organism has extra sets of chromosomes

postzygotic isolation

reproductive isolation that occurs after members of two different species have mated and produced a hybrid offspring. Such hybrids are usually unable to reproduce

prezygotic isolation

a barrier to successful breeding that occurs before fertilization, such as differences in mating time or behavior

reinforcement

an evolutionary process where natural selection strengthens prezygotic reproductive barriers between populations, preventing the production of unfit hybrid offspring

reproductive isolation

Separation of species or populations so that they cannot interbreed and produce fertile offspring

secondary contact

when two populations that have diverged in isolation from a common ancestor are reunited geographically

self-fertilization

the fertilization of plants and some invertebrate animals by their own pollen or sperm rather than that of another individual.

speciation

Formation of new species

species

A group of similar organisms that can breed and produce fertile offspring.

subspecies

variations of a species that live in different geographic areas

sympatric speciation

The formation of new species in populations that live in the same geographic area

sympatry

Condition in which two or more populations live in the same geographic area, or close enough to permit interbreeding.

sympatric speciation

The formation of new species in populations that live in the same geographic area

synapomorphy

shared derived characteristics

temporal isolation

form of reproductive isolation in which two populations reproduce at different times

tetraploid

four sets of chromosomes

triploid

three sets of chromosomes

vicariance

the physical splitting of a habitat