Unit 7: Topic 10 - Speciation Flashcards
What can happen when two species become reproductively isolated?
Speciation. When reproductive isolation occurs between two populations, each population can accumulate their own unique characteristics and become individual species.
What is the definition of a species?
A group of sexually reproducing organisms that can interbreed and exchange genetic information.
What is the difference between gradualism and punctuated equilibrium in evolution?
In evolution, gradualism is when evolution constantly occurs but at a slow rate, while punctuated equilibrium is when evolution happens in a period of rapid change after stasis/no evolutionary change. Note: periods of time over millions of years.
What is divergent evolution and when does it occur?
Divergent evolution occurs when species sharing common ancestry develop different phenotypes due to different selective pressures, such as environmental changes, predation, and competition. One example involves Darwin’s findings regarding the Galapagos finch, in which the finches he found had homologous beak structures, proving their divergence from a common ancestor finch.
What is adaptive radiation and what is the rate of speciation during it?
Adaptive radiation is the rapid increase in speciation due to an increased amount of available niches. New niches can be created by environmental change, predation, or competition.
How does speciation affect biodiversity?
Speciation increases biodiversity which in turn benefits the population.
What is the difference between sympatric and allopatric speciation?
Allopatric speciation occurs when there is a geographical separation of the two groups of organisms involved, while sympatric speciation occurs when there is no geographical separation, commonly due to polyploidy, which is when cells have more than one pair of chromosomes.
What are the prezygotic barriers that separate species?
Two populations can be separated and eventually undergo speciation due to the following prezygotic barriers: habitat isolation (occupation of different habitats), temporal isolation (different timing of reproduction), mechanical isolation (different reproductive structures), gametic isolation (different eggs or sperm cells), or behavioral isolation (different mating preferences).
What are the postzygotic barriers that separate species?
Postzygotic barriers include sterilization (inability to produce offspring), inviability (early embryonic death), and abnormality (abnormal development and/or survival rates).
