Genetics of natural populations. XXXI. Genetics of an isolated marginal population of Drosophila pseudoobscura.
نویسندگان
چکیده
AYR (1954, 1959), CARSON (1955,1956,1959), BROWN (1957), DOBZHANM s ~ ~ (1957 and other publications), TOWNSEND (1952) and others have pointed out that the genetic structures of populations of the same species inhabiting the central and the peripheral parts of the distribution area are likely to be characteristically different on the average. Central populations have, by and large, mastered a greater range of ecological niches, and have thus achieved a more secure adaptedness to the environment than the peripheral ones, which may well be able to survive in only a restricted adaptive zone. The form of natural selection which predominates in central populations has been termed by CARSON (Zoc. cit.) heteroselection; it favors polymorphism, restricted recombination, and a general adaptedness to a multiplicity of conditions. Marginal populations are dominated by homoselection, which favors a relative homozygosity, random genetic drift, free recombination, and adaptive specialization. Evolutionary novelties, such as new species, are, however, more likely to arise, in the opinion of most writers, from the marginal rather than from the central populations. The population of Drosophitila pseudoobscuru discovered in the Andes of Colombia around Bogota occurs in an apparently small area isolated from the main body of the species by extensive territories in which the species in all likelihood does not occur. The results of a cytological and genetic analysis of this population are reported in the pages that follow.
منابع مشابه
Further studies on gene polymorphism in the mainbody and geographically isolated populations of Drosophila pseudoobscura.
We have examined polymorphism at 22 additional loci in the populations from the mainbody of Drosophila pseudoobscura and an isolated population from Bogotá, Columbia, which also shows partial reproductive isolation from mainbody populations. These studies extend our previous observations of reduced gene polymorphism and apparent lack of unique allele in the Bogotá population.
متن کاملGenetic studies of natural populations of Drosophila: Drosophila pseudoobscura, a large dominant population.
F O R several years members of this laboratory have studied the genetic structure of Drosophila populations. None of these populations has been a large dominant continental population. PROFESSOR TH. DOBZHANSKY and his colleagues have analyzed samplemf Drosophila willistoni, the major Neotropical Drosophila with the largest population of any Drosophila known, and Drosophila pseudoobscura, which ...
متن کاملGenetics of Natural Populations. III Gene Arrangements in Populations of Drosophila Pseudoobscura from Contiguous Localities.
EVENTEEN gene arrangements, related to each other as single or S multiple inversions, were described by DOBZHANSKY and STURTEVANT (1938) in the third chromosome of Drosophila pseudoobscura. Some of these gene arrangements have a wide, and others a narrow geographical distribution. In some localities the entire population is uniform, but more commonly several arrangements are found together. Dif...
متن کاملGene flow and the geographical distribution of a molecular polymorphism in Drosophila pseudoobscura.
This paper discusses the relation between the geographical distribution of an enzyme polymorphism and population structure in Drosophila pseudoobscura. California populations of this species living in very different montane and lowland habitats separated by several kilometers are similar to each other in the frequency of an esterase allele. Previous estimates suggest that gene flow is too limit...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Genetics
دوره 48 شماره
صفحات -
تاریخ انتشار 1963