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23 Cards in this Set
- Front
- Back
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What is anagensis? |
Species formation without branching of the evolutionary line of descent. In anagenesis, the old species evolves into a new species, but the old species no longer exists. |
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What is cladogenesis? |
The formation of a new group of organisms or higher taxon by evolutionary divergence from an ancestral form.In cladogenesis, a small subset of an existing species evolves into a new species by adapting to a new environment, but the old species continues to persist, relativley unchanged, at the same time as the new species. |
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What is speciation? |
The formation of new and distinct species in the course of evolution. |
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Complete the analogy: speciation is to extinction as birth is to ________. |
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Why did Darwin call speciation the ‘mystery of mysteries’? |
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What is microevolution? |
Evolutionary change within a species or small group of organisms, especially over a short period. |
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What is macroevolution? |
Major evolutionary change. The term applies mainly to the evolution of whole taxonomic groups over long periods of time. |
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How does speciation occur? |
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What is reproductive isolation? |
Reproductive isolation refers to the situation where different species may live in the same area, but properties of individuals prevent them from interbreeding. The things which stop species or groups of organisms reproducing sexually are called isolating mechanisms. |
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Describe prezygotic and postzygotic barriers to gene flow. |
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Why do hybrids sometimes have reduced viability and/or fertility? |
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What is hybrid breakdown? |
Hybrid breakdown is a type of reproductive failure that appears after the F2 generation of crosses between different species or subspecies. It is caused by incompatibility between interacting genes. |
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What is sympatric speciation? |
Sympatric speciation is the process through which new species evolve from a single ancestral species while inhabiting the same geographic region. |
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What is allopatric speciation? |
Allopatric speciation is just a fancy name for speciation by geographic isolation, discussed earlier. In this mode of speciation, something extrinsic to the organisms prevents two or more groups from mating with each other regularly, eventually causing that lineage to speciate. |
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Why is sympatric speciation thought to be rarer than allopatric speciation? |
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What is polyploidy? |
Polyploidy is the process of genome doubling that gives rise to organisms with multiple sets of chromosomes. The term ploidy (see glossary for this and other related terms) refers to the number of complete genomes contained in a single cell. |
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What is an autopolyploid? |
Autopolyploids are polyploids with multiple chromosome sets derived from a single species. Autopolyploids can arise from a spontaneous, naturally occurring genome doubling, like the potato. |
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What is an allopolyploid? |
Allopolyploids are polyploids with chromosomes derived from different species. Precisely it is the result of multiplying the chromosome number in an F1 hybrid. |
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What are hybrid zones and how do they develop? |
Image result for definition of hybrid zoneHybrid zones are locations where the hybrid offspring of two divergent taxa (species, subspecies or genetic "forms") are prevalent and there is a cline in the genetic composition of populations from one taxon to the other. |
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What is a hybrid swarm? |
A hybrid swarm is a population of hybrids which contains parent types, and offspring types, and intermediate types all mingled together and back-crossing and cross pollinating each other. Hybrid swarms are characterized by huge phenotypic differences between individuals. |
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What is meant by punctuated and gradual patterns in evolutionary history? |
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Why are there many species (i.e., instead of just one)? |
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What allows for species coexistence? |
The term niche differentiation (synonymous with niche segregation, niche separation and niche partitioning), as it applies to the field of ecology, refers to the process by which competing species use the environment differently in a way that helps them to coexist. The competitive exclusion principle states that if two species with identical niches (i.e., ecological roles) compete, then one will inevitably drive the other to extinction.[1] When two species differentiate their niches, they tend to compete less strongly, and are thus more likely to coexist. |
