Question

Explain the difference between "allopatric speciation" and "sympatric speciation". Provide an example.

Answer 1

Answer:

Explanation:          

Is geographic isolation needed?

Yes (allo)     No  (sym)

Major differentiation mechanism

Natural selection(allo ) Polyploidy  (sym)

Speed of creation of new species

Slow(allo..)  Autopolyploidy – fast; allopolyploidy – slow (sym.. )

Common in nature?

Yes (allo..) Yes – in plants (sym)

Examples Darwin’s Finches; squirrels in the Grand Canyon(allo )

                        Cultivated cor.n, wheat and tobacco(sym)

Allopatric Speciation

Allopatric comes from the Greek words allos meaning “other” and patris which means “fatherland.” Allopatric speciation occurs when a population of organisms becomes separated or isolated from their main group. Over time, the allele frequency in the new group, which used to be homogenous across the individuals, becomes subject to changes via natural selection due to of pressure from differences in predators, climate, competitors and resources. Populations can become isolated for a variety of reasons. Some examples are changes in land topography resulting from earthquakes, seeds dispersed by the wind and carried away in rivers, flooding, migration and erosion. Two examples of allopatric speciation are Darwin’s Finches and populations of squirrels in the Grand Canyon. Research has shown that the greater the distance of separation, the greater the odds that speciation will occur.

Sympatric Speciation

The term sympatric comes from the English prefix sym- meaning “same” or “together” and the Greek word patris which means “fatherland.” This type of speciation happens in a population without geographic isolation. The main mechanisms resulting in sympatric speciation involve changes in the chromosomes of the organism. One way this happens is when there is a serious error that occurs during cell division resulting in more than one copy of a chromosome(s), or the loss of a chromosome(s), in one of the daughter cells. This condition is known as aneuploidy and there are two main kinds:

i) Autopolyploidy

ii) Allopolyploidy