Ch17 Speciation Flashcards
Groups of organisms that mate with each other
Species
Theorem by Carolus Linnaeus states that organisms that look alike are the same species and those who don’t are not.
Morphological Species Concept
A state in which two groups of organisms may no longer share genes
Reproductive Isolation
“Species are groups of ACTUALLY OR POTENTIALLY(Key phrase here!!!) interbreeding natural populations which are reproductively isolated from other such groups.” - Ernst Mayr
Biological Species Concept
Species branch off and create two or more daughter species, which thereafter, evolve as distinct lineages
Lineage Species Concept
Speciation that results when a population is divided by a physical barrier
Allopathic Speciation
Speciation without physical limitation
Sympathetic Speciation
The most common means of sympathize speciation, or the duplication of sets of chromosomes within individuals.
Polyploidy
Mechanisms that prevent hybridization from occurring
Prezygotic isolating mechanisms
Mechanisms that reduce the fitness of hybrid offspring
Postzygotic Isolation Mechanisms
Prezygotic isolating mechanisms can prevent hybridization in several ways.. They are:
Mechanical isolation, Temporal Isolation, Behavioral Isolation, Habitat Isolationation, Gametic Isolation
These may form is reproductive isolation is incomplete
Hybrid Zones
Differences in the size and shape of reproductive organisms that may prevent the Union of gametes from different species.
Mechanical Isolation
Many Organisms have Different mating times or seasons, thus reproductively isolating them
Temporal Isolation
Species may reject, or fail to recognize, individuals of other species as potential mating partners
Behavioral Isolation
Two closely related species that don’t reproduce with each other, because of living habitat preferences
Habitat isolation
The Sperm of one species may not attach to the eggs of another species because the eggs do not release the appropriate attractive chemicals, or the sperm may be unable to penetrate the egg and the gametes are chemically incompatible
Gametic Isolation
Prezygotic isolating mechanisms hat result in selection against hybridization
Low hybrid zygote viability, low hybrid adult vitality, Hybrid infertility
Hybrid Zygotes may fail to mature normally, either dying during development or developing phenotypic abnormalities hat prevent them from becoming reproductively capable adults
Low Hybrid Zygote Viability
Hybrid offspring may have lower survivorship than non-hybrid offspring
Low Hybrid Adult Viability
Hybrids may mature into infertile adults. For example, the offspring of makings between horses and donkeys—mules—are sterile; although they are otherwise Beale, they produce no descendants.
Hybrid Infertility
The divergence of biological lineages and the emergence of reproductive isolation between lineages.
Speciation
