Chapter 22 Flashcards
What is the biological species concept?
It defines species as groups of populations that have the potential to interbreed and that are reproductively isolated from other groups.
What is sympatric speciation?
Differentiation of populations within a common geographic area into species
What do gene pools have?
All alleles present in a species
What the definition of a reproductive isolating mechanism?
Any barrier that prevents genetic exchange between species
What are prezygotic isolating mechanisms?
The formation of the zygote is prevented.
What are Postzygotic isolating mechanisms?
the zygote is formed but the offspring can not reproduce (infertile)
What is the ecological species concept?
Distinctions among species are maintained by natural selection
Why is the ecological species concept difficult to apply?
Because populations are geographically separated in nature
How does is reproductive isolation reinforced?
In speciation, the process by which reproductive isolation between populations is increased by selection against mating between members of the two population eventually resulting in reproductive isolation.
What are the two possible outcomes when two populations that are partially reproductively isolated become sympatric?
- gene flow occurs between them
- hybrids reproduce with other members of the population and they will serve as a means of genetic exchange.
What is the effect of genetic drift on a population?
Random change in small populations, founder effects, and population bottlenecks all may lead to changes in traits that cause reproductive isolation.
How can genetic drift and natural selection lead to speciation?
Natural selection causes them to accumulate many differences to adapt leading to reproductive isolation.
What is allopatric speciation?
It takes place when populations are geographically isolated
What is polyploidy?
a condition in which one or more entire sets of chromosomes instantaneously is added to the diploid genome.
autopolyploidy?
results in meotic error
What is allopolyploid
it is contains genomes of two or more species
What is distrubtive selection?
It causes populations to have two different phenotypes
What is adaptive radiation
The evolution of several divergent from a primitive and unspecialized ancestor
What is key innovation
Allows members to use a new resource from an adaptation
What is stasis?
A period of time during which little evolutionary change occurs
What is gradual evolutionary change?
The view that species change very slowly in ways that may be imperceptible from one generation to the next but that accumulate and lead to major changes over thousands or millions of years.
What is the punctual equilibrium hypothesis?
A hypothesis about the mechanisms of evolutionary change proposing that long periods of little or no change are punctuated by periods of rapid evolution.
Define mass extinction
a relatively sharp decline in the number of species.
