Definitions of species Flashcards
What is the ecological species concept?
A species is determined by individuals that share the same niche and the same resources. The occupy the same space.
What it the phylogenetic species concept?
A species is determined by genetically different individuals, but that come from a common ancestor.
What is the morphological / phenetic species concept?
A species is determined by individuals that are similar., be it in their morphology, their biochemistry, their genetics, their molecular genetics.
What is the biological species concept?
Members of a population that can interbreed and have fertile offspring. These members share the same gene pool. There is reproductive isolation to prevent breeding between two species.
What are the drawbacks of the phenetic species concept?
Some species look alike, but are different species and some of the same species can look very different (ex. types of dogs)
What are the drawbacks for the biological species concept?
- Does not apply to asexually-reproducing species
- Cannot be applied to extinct species
- Cannot be applied between geographically isolated species (bc. cannot interbreed or we cannot examine if they can)
How can there be isolation to prevent breeding between species?
Many ways:
- ecological/habitat isolation (live diff places)
- Temporal isolation (no mate same time year)
- Behavioral isolation (incompatible reprod. signals)
- Mechanical isolation (anatomically incomptatible)
- Gamete isolation (egg and sperm may not recognize each other or cannot survive in female internal envir.)
- Gen incompatibility
- Hybrid inviability (embryo not develop)
- Hybrid lives, but low/sterile (not fit) (stops gene flow)
- Hybrids breakdown (they are fertile, so can continue)
What is the general process of speciation?
Something prevents gene flow between the populations, then the populations accumulate genetic differences so that they diverge so much that they are incompatible to mate with other ones. When there is an increased reproductive isolation, it develops to new species.
What is the difference between sympatric and allopatric speciation?
Allopatric speciation happens when two species are separated by a physical, geographical barrier. Sympatric speciation happens when two species are reproductively isolated but that it they are in the same geographic area.
What conditions favor allopatric speciation?
A small population, genetic drift and a new environment.
What events can lead to a decrease in gene flow, leading to sympatric speciation?
A new ecological barrier zone (Small area with different selection pressures), a sub-population becomes linked to a specific resource, assortative mating between specific phenotypes, new sexual preference.
What are the chromosomal speciation processes?
Autopolyploidy in which the chromosome number is doubled. They become isolated from the other ones bc. 4nx2n = 3n.
Allopolyploidy is when 2 different species combine to form polyploidy hybrids.
