Term
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Definition
Involves the splitting of evolutionary lineages
-need not involve adaptation
-Darwins mystery of mysteries |
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Term
| Basic patterns of evolutionary change |
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Definition
| anagenesis and cladogenesis |
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Term
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Definition
| phyletic change, is the evolution of species involving an entire population |
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Term
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Definition
-evolutionary splitting event in a species in which each branch and its smaller branches forms a clade
-an evolutionary mechanism and a process of adaptive evolution that leads to the development of a greater variety of sister organisms
-provides independent evolutionary lineages |
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Term
| Biological Species Concept |
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Definition
defines 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 unable to produce viable offspring with members of other populations
-focuses the study of speciation on the evolution of reproductive isoaltion
-Ernst Mayr |
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Term
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Definition
existence of biological factors that impede members of two species from producing viable fertile hybrids
-allow lineages to evolve separately
-prezygotic and postzygotic barriers |
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Term
| Limitations of Biological Species Concept |
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Definition
-doesn't apply to asexual organisms, fossils, and organisms of which little is known regarding their reproduction
-some species hybridize frequently to the point where their ranges overlap yet maintain their differences |
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Term
| Morphological Species Concept |
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Definition
| characterizes a species in terms of body shape, size, and other structural features |
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Term
| Paleontological species concept |
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Definition
| focuses on morphologically discrete species known only from fossil records |
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Term
| Ecological species concept |
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Definition
| views species in terms of its ecological niche |
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Term
| Phylogenetics species concept |
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Definition
| defines a species as a set of organisms with unique genetic history |
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Term
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Definition
| impede mating between species or hinder fertilization of ova if members of different species try to mate |
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Term
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Definition
| prevent the hybrid zygote from developing into viable, fertile adult |
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Term
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Definition
need not evolve as mechanism to avoid hybridization but rather evolves as a consequence of adapation(s) to improve survival or mating success in a particular population or species
-could evolve to prevent matings that produce unfit hybrids (reinforcement)
-evidence: greater premating isolation between sympatric than allopatric populations of two species |
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Term
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Definition
develops over time with genetic isolation of populations
-result of divergence at one or more loci such that combinations of alleles from the two species result in low fitness
-divergence could be due to selection or drift |
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Term
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Definition
| allopatric, sympatric, parapatric speciation |
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Term
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Definition
gene flow interrupted/reduced when population is divided into two or more geographically isolated subpopulations
-known as 'other country' speciation
-ex. A. harrisi and A. leucurus species of squirrels at each side of grand canyon |
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Term
| Dobzhansky-Muller incompatibilities |
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Definition
-arise in allopatry and result in isolation
-may arise with or without the aid of selection therefore reproductive isolation and adaptation may be decoupled |
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Term
| D-M incompatibility example |
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Definition
1.Two allopatric populations of a species are originally fixed for the same alleles at two loci (both populations A1A1B1B1).
2.Through selection or drift one population becomes fixed for a new allele at the B locus (A1A1B2B2).
3.In that population, a new allele at the A locus arises and is fixed (A2A2B2B2).
4.When populations hybridize and recombine, the A2 allele will be mixed with the B1 allele in some offspring. The A2B1 combination may be deleterious because A2 has never had to function with the B1 allele.
Such reductions in hybrid fitness are called D-M incompatibilities. |
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Term
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Definition
-'same-country' speciation
-divergence and speciation take place without geographic isolation
-difficult because genes causing divergence must be linked to or the same as those causing reproductive isolation (assortative mating)
-appears to require simultaneous evolution of trait divergence and assortative mating
-ex. -evolution of plant host races of the same insect species
-genes that cause host preference may lead to assortative mating |
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Term
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Definition
Adjacent populations diverge usually in response to some strong ecological gradient
-ex. flower colors and organism preference |
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Term
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Definition
presence of extra sets chromosomes due to accidents during cell division
-results in reproductive barriers between different ploidy levels |
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Term
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Definition
| more than two chromosome sets all derived from a single species |
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Term
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Definition
| polyploids with chromosomes derived from different species |
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Term
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Definition
gradual divergence between adjacent forms
-ex. song complexity of greenish warblers increase in complexity around different sides of the ring (more structures and foliage) |
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Term
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Definition
evolution of diversely adapted species from a common ancestor upon introduction to new environmental opportunities
-ex. Hawaiian archipelago |
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