Chapter 13: Adaptation and Speciation

biological fitness

individual’s survival and successful reproduction

biological species concept

idea that a species is defined as a group of natural populations that an interbreed to produce fertile offspring and cannot breed with other such groups

species

1. members of a group that an mate with one another to produce fertile offspring

2. smallest unit of classification in the Linnaean hierarchy

reproductive isolation

condition in which barriers prevent populations from interbreeding

morphology

organism’s physical characteristics

morphological species concept

idea that a species is defined as a group with similar physical characteristics, some of which are unique to the group

ecological species concept

idea that a species is defined as a group with a unique role in their community

phylogenetic species concept

idea that a species is defined as a group with a shared and unique evolutionary history leading to a high degree of DNA similarity

speciation

process by which one species splits to form two species or more

genetic divergence

accumulation of differences in the DNA sequences in two or more populations or organisms over time

allopatric speciation

formation of new species from geographically isolated populations

geographic isolation

condition in which populations are separated by physical barriers

sympatric speciation

formation of new species in the absence of geographic isolation

reproductive barrier

barrier that prevents two species from interbreeding, making them reproductively isolated

prezygotic barrier

barrier that prevents a male gamete and a female gamete from fusing to form a zygote

reproductive barrier that acts before a zygote exists

ecological isolation

condition in which closely related species in the same territory are reproductively isolated by slight differences in habitat

temporal isolation

condition in which closely related species in the same territory are reproductively isolated by slight differences

mechanical isolation

condition in which closely related species in the same territory are reproductively isolated by physical differences that do not allow the mating process to occur

behavioral isolation

condition in which closely related species in the same territory are reproductively isolated by differences in mating rituals

gametic isolation

condition in which closely related species in the same territory are reproductively isolated by differences in gametic structures that do not allow fertilization

postzygotic barrier

barrier that prevents a zygote from developing into a healthy and fertile individual

reproductive barrier that acts after a zygote exists

reduced hybrid viability

postzygotic reproductive barrier in which hybrids don’t survive to reproduce

reduced hybrid fertility

postzygotic reproductive barrier in which hybrids are infertile

hybrid breakdown

postzygotic reproductive barrier in which hybrids can produce successful and fertile offspring, but the F2 generation are not viable and/or fertile

polyploidy

condition in which an individual’s somatic cells have more than two sets of chromosomes

coevolution

tandem evolution of two species that results because interaction between the two so strongly influences their survival