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Bio 05 Species
| Question | Answer |
|---|---|
| Species | A group of organisms that maintains a distinctive set of attributes in nature, has the potential to interbreed with one another in nature to produce viable, fertile offspring but cannot successfully interbreed with members of other species |
| Speciation | The emergence of new species from pre-existing ones |
| Macroevolution | Evolutionary changes that occur over a long period of time that can result in a new species and groups of species |
| Taxonomy | The branch of biology that names and classifies species and groups them into broader categories |
| 5 species concepts | 1. Phylogenetic 2. Biological 3. Morphological 4. Ecological 5. Evolutionary |
| Reproductive isolation | Prevents breeding with other species |
| Morphological species concept | A species is a population or group of populations that differs morphologically from other populations. Classifies organisms based on observable phenotypic traits |
| Phylogenetic species concept | Smallest aggregation of sexual or asexual populations that contains unique combination of characteristics that identifies that group of individuals as distinct from other species. Physical traits used to be used, now both molecular data and morphology |
| Evolutionary (or "Darwinian") species concept | A species is derived from a single lineage that is distinct from other lineages and has its own evolutionary tendencies and historical fate |
| Ecological species concept (Van Valen) | Considers each species occupies a unique ecological niche. Within their own niche, members of a given species compete for survival. If 2 organisms are very similar, their needs will overlap, which results in competition |
| Reproductive barriers | Serve to isolate a species gene pool and prevent interbreeding. Categorized as prezygotic or postzygotic, depending on whether they function before or after zygotes form |
| Prezygotic barriers | Prevent formation of zygote |
| Postzygotic barriers (Uncommon) | Block development of viable, fertile individuals. Operate AFTER hybrid zygotes are formed |
| Interspecies hybrid | When 2 species produce offspring |
| Temporal isolation | 2 species breed at different times (seasons, times of day, years). Mate at different times |
| Habitat isolation | 2 species live in the same general area but not in the same kind of place. Physical separation and geographic barrier prevent contact |
| Behavioral isolation | There is little or no sexual attraction between species, due to specific behaviors. 1. Different courtship behaviors 2. Behaviors important in mate choice |
| Mechanical isolation | Female and male sex organs are not compatible. Mating is physically difficult or impossible: size or incompatible genitalia prevents mating between 2 species |
| Gametic isolation | Female and male gametes are not compatible. Gametes fail to unite successfully, so no fertilization occurs. Important in species that release gametes into the water or air |
| Reduced hybrid viability | Most hybrid offspring do not survive |
| Reduced hybrid fertility | Hybrid offspring are vigorous but sterile |
| Hybrid breakdown | The first-generation hybrids are viable and fertile, but the offspring of the hybrids are feeble or sterile |
| 2 Requirements for speciation | 1. Reproductive isolation of populations 2. Genetic divergence |
| Allopatric speciation | Physical barrier divides population |
| Peripatric speciation | Small founding population enters isolated niche |
| Parapatric speciation | New niche found adjacent to original one |
| Sympatric speciation | Speciation occurs without physical separation. Occurs as a result of new species evolving from a single ancestral species while inhabiting the same geographic region |
| Anagenesis | A single species transformed into a different species over the course of many generations |
| Cladogenesis | A division of a species into 2 or more species when some members of a species become geographically separated and 2 or more new species emerge |
| Genetic divergence occurs by... | 1. Different selective pressures 2. Different mutations that arise in each populations' gene pool |
| Bottleneck | Events result in only a few individuals surviving genetic variability is reduced (ex. overhunting and volcanism) |
| Founder effect | The reduction in genomic variability that occurs when a small group of individuals become separated from a larger population |
| 4 factors that play a role in adaptive radiations | 1. Lack of competitors 2. Varying habitats 3. Food sources 4. Evolution of new structures |
| Possible consequence of peripatric speciation | A geographically widespread ancestral species becomes paraphyletic. Ex. The evolution of the polar bear from the brown bear |
| Parapatric speciation occurs as a result of... | Dimorphism between populations of a species, and simultaneous variation in mating habits, within a continuous geographical area. Occurs when populations are separated not by a geographical barrier, like a body of water, but by an extreme habitat change. |
| Ecological isolation of a population can lead to _________ speciation. This is called _________ _________ | Sympatric. Sympatric isolation |
| Hybridization creates abrupt genetic changes that quickly lead to the... | Reproductive isolation of a group of individuals Ex. Changes in chromosome number |
| Polyploidy | The heritable condition of possessing more than 2 complete sets of chromosomes. Played an essential role in the domestication of many crops. Polypoid species are reproductively isolated from diploid sister species |
| What causes extinction? | Localized distribution and overspecialization, singular food source, small population size, interaction with other organisms, and habitat change and destruction |
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