Chapter 17
Lineage Species Concept
A species is a single lineage of ancestor-descendant populations which maintain its identity from other such lineages and which has it own evolutionary tendencies and historical fate
Gametic Isolation
A type of prezygotic barrier. Gametic isolation happens when the egg and sperm are released but a zygote is not formed. Reproductive cells are not compatible
Postzygotic Isolating Mechanisms
A type of reproductive isolating mechanism which comes into play after the gametes of two different species have fused to create a hybrid zygote. These mechanisms may prevent the proper development of the hybrid and/or make it infertile, thus the hybrid is unable to successfully reproduce.
Cryptic Species
Cryptic speciation is a biological process that results in a group of species (which, by definition, cannot interbreed) that contain individuals that are morpholigically identical to each other but belong to different species.
Prezygotic Isolating Mechanisms
Reproductive isolating mechanisms which prevent the formation of a zygote between members of different species. These mechanisms include geographical isolation, ecological isolation, temporal isolation, behavioral isolation, mechanical isolation, and gametic isolation.
Sympatric Speciation
Speciation due to reproductive isolation without any physical separation of the subpopulation.
Allopatric Speciation
The formation of two species from one when reproductive isolation occurs because of a physical geographic barrier.
Speciation
The process of splitting one population into two populations that are reproductively isolated from one another.
Reproductive Isolation
When isolating mechanisms make it so two species can not reproduce.
Biological Species Concept
Where one species is reproductively isolated from another species, meaning they cannot breed and reproduce with species other than their own.
Temporal Isolation
A form of prezygotic isolation that prevents species from mating because they mate at different times.
Mechanical Isolation
A form of prezygotic isolation where the size and shape of an organisms genitalia can only fit into that of its own species.
Morphological Species Concept
Organisms are classified in the same species if they appear identical
Polyploidy
Polyploid cells and organisms are those containing more than two paired (homologous) sets of chromosomes.
Behavior Isolation
Prezygotic isolation usually in the form of mating rituals and signals. Signals that attract mates to each other may be one of the most important factors in determining whether closely related species mate with each other or not.
Habitat (Ecological) Isolation
Prezygotic isolation where species may live in the same place but different habitats. For example one lives underground while the other lives in a tree
Reinforcement
Reinforcement is the process by which natural selection increases reproductive isolation.
Hybrid Breakdown
hybrid produces offspring but offspring not viable or fertile
Punctuated Equilibrium
long periods of stasis punctuated by episodes of speciation. species develop in spurts of rapid NOT slow & gradual change
Low Hybrid Fertility
the hybrid is sterile
Low Hybrid Viability
zygote fails to develop or reach sexual maturity