Crying Rock
Member
The Barbarian said:
Except micro can be directly observed, repeatedly.
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Except micro can be directly observed, repeatedly.
Crying Rock
Member
The Barbarian said:
Please elaborate.
Barbarian
Member
http://www.genetics.org/cgi/reprint/18/4/293.pdf
Dobzhansky and Pavlovsky (1971) reported a speciation event that occurred in a laboratory culture of Drosophila paulistorum sometime between 1958 and 1963. The culture was descended from a single inseminated female that was captured in the Llanos of Colombia. In 1958 this strain produced fertile hybrids when crossed with conspecifics of different strains from Orinocan. From 1963 onward crosses with Orinocan strains produced only sterile males. Initially no assortative mating or behavioral isolation was seen between the Llanos strain and the Orinocan strains. Later on Dobzhansky produced assortative mating (Dobzhansky 1972).
...
One example of evolution at work is the case of the hawthorn fly, Rhagoletis pomonella, also known as the apple maggot fly, which appears to be undergoing sympatric speciation.[13] Different populations of hawthorn fly feed on different fruits. A distinct population emerged in North America in the 19th century some time after apples, a non-native species, were introduced. This apple-feeding population normally feeds only on apples and not on the historically preferred fruit of hawthorns. The current hawthorn feeding population does not normally feed on apples. Some evidence, such as the fact that six out of thirteen allozyme loci are different, that hawthorn flies mature later in the season and take longer to mature than apple flies; and that there is little evidence of interbreeding (researchers have documented a 4-6% hybridization rate) suggests that sympatric speciation is occurring. The emergence of the new hawthorn fly is an example of evolution in progress.
http://en.wikipedia.org/wiki/Speciation
Dobzhansky and Pavlovsky (1971) reported a speciation event that occurred in a laboratory culture of Drosophila paulistorum sometime between 1958 and 1963. The culture was descended from a single inseminated female that was captured in the Llanos of Colombia. In 1958 this strain produced fertile hybrids when crossed with conspecifics of different strains from Orinocan. From 1963 onward crosses with Orinocan strains produced only sterile males. Initially no assortative mating or behavioral isolation was seen between the Llanos strain and the Orinocan strains. Later on Dobzhansky produced assortative mating (Dobzhansky 1972).
...
One example of evolution at work is the case of the hawthorn fly, Rhagoletis pomonella, also known as the apple maggot fly, which appears to be undergoing sympatric speciation.[13] Different populations of hawthorn fly feed on different fruits. A distinct population emerged in North America in the 19th century some time after apples, a non-native species, were introduced. This apple-feeding population normally feeds only on apples and not on the historically preferred fruit of hawthorns. The current hawthorn feeding population does not normally feed on apples. Some evidence, such as the fact that six out of thirteen allozyme loci are different, that hawthorn flies mature later in the season and take longer to mature than apple flies; and that there is little evidence of interbreeding (researchers have documented a 4-6% hybridization rate) suggests that sympatric speciation is occurring. The emergence of the new hawthorn fly is an example of evolution in progress.
http://en.wikipedia.org/wiki/Speciation
Crying Rock
Member
The Barbarian said:
I appreciate the examples.
http://en.wikipedia.org/wiki/Sympatric_speciation
"...takes place when sexually reproducing organisms choose to mate with individuals that are similar (positive assortative mating) or dissimilar (negative assortative mating) to themselves in some specific manner...."
http://en.wikipedia.org/wiki/Assortative_mating
O.K., I think we've beaten this thread to death. It was a pleasure to exchange ideas.
CR
Barbarian
Member
Turns out it was. No one was messing with the population; it just diverged by founder effect. This is a common mode of speciation; a small population is separated from the larger group, and in isolation the particular mix of alleles in the small group eventually leads to a new species.
The second speciation, that of hawthorn to apple flies, was entirely outside of the lab.