%0 Journal Article %1 wright1946genetics %A Wright, S %A Dobzhansky, T %D 1946 %J Genetics %K Drosophila experimental_evolution inversions pseudoobscura seasonal_adaptation temporal_variation %N 2 %P 125-156 %T Genetics of Natural Populations. XII. Experimental Reproduction of Some of the Changes Caused by Natural Selection in Certain Populations of Drosophila Pseudoobscura %U http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1209320/ %V 31 %X RAPID changes in the genetic composition occlir in populations of Dro- sophila pseudoobscura which inhabit certain localities on Mount San Ja- cinto, California (DOBZHANSKY 1943). These changes are cyclic and connected with the succession of the year's seasons. The genetic variable involved is the gene arrangement in the third chromosome. Three gene arrangements are common among the third chromosomes of the San Jacinto populations. One of them, called Standard (abbreviated ST), is most frequent in the populations in winter and in early spring, reaches its lowest frequency in early summer, and increases in frequency during middle and late summer. The second, Chiricahua (abbreviated CH), shows a cycle opposite to that of ST. The third, Arrowhead (AR), tends to follow a path resembling that of CH but with less regularity. Inversion homozygotes and heterozygotes occur in the populations with frequencies which are close to those which are expected if the carriers of the different gene arrangements mate a t random. Analysis of the data has led to the working hypothesis according to which the changes in the relative frequencies of the gene arrangements are induced by natural selection in response to the seasonal alterations in the environment. The gene arrangements may be in themselves adaptively neutral (that is, free from position effects), but they contain different gene complexes which make their carriers adapted to different seasonal environments (DOBZHANSKY 1943). Since the changes in the composition of the populations are consider- able and rapid, the chromosomal types concerned must be subject to intense selection pressures. The selective advantages and disadvantages that must be postulated are, indeed, high enough to justify an attempt to detect them in laboratory experiments. The present article reports the results of experi- ments designed to test the validity of the above hypothesis.

@article{wright1946genetics, abstract = {RAPID changes in the genetic composition occlir in populations of Dro- sophila pseudoobscura which inhabit certain localities on Mount San Ja- cinto, California (DOBZHANSKY 1943). These changes are cyclic and connected with the succession of the year's seasons. The genetic variable involved is the gene arrangement in the third chromosome. Three gene arrangements are common among the third chromosomes of the San Jacinto populations. One of them, called Standard (abbreviated ST), is most frequent in the populations in winter and in early spring, reaches its lowest frequency in early summer, and increases in frequency during middle and late summer. The second, Chiricahua (abbreviated CH), shows a cycle opposite to that of ST. The third, Arrowhead (AR), tends to follow a path resembling that of CH but with less regularity. Inversion homozygotes and heterozygotes occur in the populations with frequencies which are close to those which are expected if the carriers of the different gene arrangements mate a t random. Analysis of the data has led to the working hypothesis according to which the changes in the relative frequencies of the gene arrangements are induced by natural selection in response to the seasonal alterations in the environment. The gene arrangements may be in themselves adaptively neutral (that is, free from position effects), but they contain different gene complexes which make their carriers adapted to different seasonal environments (DOBZHANSKY 1943). Since the changes in the composition of the populations are consider- able and rapid, the chromosomal types concerned must be subject to intense selection pressures. The selective advantages and disadvantages that must be postulated are, indeed, high enough to justify an attempt to detect them in laboratory experiments. The present article reports the results of experi- ments designed to test the validity of the above hypothesis.}, added-at = {2016-03-25T18:09:16.000+0100}, author = {Wright, S and Dobzhansky, T}, biburl = {https://www.bibsonomy.org/bibtex/28f64c650a6913a5a609a24453a48bc66/peter.ralph}, interhash = {286d6a53202795622a16a3c26ae543a1}, intrahash = {8f64c650a6913a5a609a24453a48bc66}, journal = {Genetics}, keywords = {Drosophila experimental_evolution inversions pseudoobscura seasonal_adaptation temporal_variation}, month = mar, number = 2, pages = {125-156}, pmid = {17247189}, timestamp = {2016-03-25T18:09:16.000+0100}, title = {Genetics of Natural Populations. {XII}. {Experimental} Reproduction of Some of the Changes Caused by Natural Selection in Certain Populations of {{Drosophila} Pseudoobscura}}, url = {http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1209320/}, volume = 31, year = 1946 }