Speciation Flashcards
What is speciation?
Speciation is the formation of a new species, often by breaking apart a single population into two groups.
What is the Marion version of natural selection?
Individuals of different genotypes have differential reproductive success in some fashion.
What are the 5 major points of natural selection?
- There is variation in a population, originally arising from mutations
- Populations tend to overproduce
- There is competition for resources
- The fittest organisms will survive and reproduce, leaving more offspring than less fit organisms
- The “fit” genes go on to become more common
What is allopatric speciation?
Speciation that occurs when two groups of a species get geographically isolated and cannot interact.
What is a cline?
A graded series of variation in a character within a species that follows a geographic line.
What is Bergmann’s Rule?
Bigger bodies farther north or in cooler regions (birds and mammals)
What is Allen’s Rule?
Extremities are shorter farther north and in cooler regions (mammals)
What is the clutch size rule?
Clutch sizes larger in northern or cooler part of range (birds and reptiles)
What are isolating mechanisms?
Means by which species remain separate
What are prezygotic methods of isolation? (4 methods)
- Ecological (habitat and temporal)
- Behavioral (calls, courtship, etc)
- Mechanical (parts do not fit)
- Gametic (egg and sperm do not fuse)
What are the postzygotic methods of isolation? (3 methods)
- Hybrid inviability
- Hybrid sterility
- Hybrid weakness
What is sympatric speciation?
Species separate while not being isolated, often due to mutations or occupying different ecological niches
What is polyploidy?
Nondisjunction of chromosomes during meiosis. It is a mechanism of sympatric speciation.
What is adaptive radiation?
Formation of several species from a common ancestor. They occupy different ecological niches. Often results in character displacement, where body parts are altered
