Population genetics of Drosophila ananassae

2015

J Genet

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Biodiversity is the sum total of all living things on the earth with particular reference to the profound variety in structure,function and genetic constitution. It includes both number and frequency of species or genes in a given assemblage and the variety of resulting ecosystems in a region. It is usually considered at three different levels: genetic, species and ecological diversities. Genus Drosophila belongs to the family Drosophilidae (class Insecta, order Diptera), characterized by rich species diversity at global level and also in India, which is a megadiverse country. At global level, more than 1500 species have been described and several thousands estimated. Hawaiian Islands are particularly rich in species diversity with more than 500 species which provides a unique opportunity to study evolution in genus Drosophila. About 150 species of Drosophila have been reported from India. Certain species of Drosophila found in India have been investigated for genetic diversity within the species. In this regard, Drosophila ananassae is noteworthy. It is a cosmopolitan and domestic species with common occurrence in India and is endowed with many genetic peculiarities. Population genetics and evolutionary studies in this species have revealed as to how genetic diversity within a species play an important role in adaptation of populations to varying environments. In addition, the work carried on D. melanogaster, D. nasuta, D. bipectinata and certain other species in India has shown that these species vary in degree and pattern of genetic diversity, and have evolved different mechanisms for adjusting to their environments. The ecological adaptations to various kinds of stress studied in certain species of Drosophila inhabiting the Indian subcontinent are also discussed.

Section: Intraspecific Genetic Variabilitymentioning

confidence: 99%

Section: Intraspecific Genetic Variabilitymentioning

confidence: 99%

Species and genetic diversity in the genus Drosophila inhabiting the Indian subcontinent

2015

J Genet

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“…The most unusual feature of this species is spontaneous male meiotic recombination in appreciable frequency (Singh 2000), which is otherwise rare in the genus. It possesses a high degree of inversion polymorphism, though only three paracentric inversions, namely sub-terminal or alpha (2L), terminal or delta (3L) and basal or eta (3R), are found to be coextensive with the species (Singh 1996). Sexual isolation, maintained by strong mating preferences has been reported between the light and dark forms of D. ananassae in laboratory stocks (Futch 1966).…”

Section: Introductionmentioning

confidence: 99%

Effect of chromosome arrangements on mate recognition system leading to behavioral isolation in Drosophila ananassae

Nanda

2011

Genetica

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The mechanisms of speciation that appear in the early stages of reproductive isolation has been of recent interest to evolutionary biologists. Experiments were conducted to study behavioral isolation between karyotypically different homozygous strains derived from natural populations of Drosophila ananassae. Three mass cultures stocks established from flies collected from natural populations were employed and homozygous stocks (ST/ST and AL/AL) were made through selection for homozygosity. By employing male-choice technique, mating success was scored by direct observation in the Elens-Wattiaux mating chamber. There is preference for homogamic matings in all the three populations and the differences between homogamic and heterogamic matings are statistically significant in two populations (Lucknow and Varanasi). These findings provide evidence that there is incipient sexual isolation between karyotypically different strains of D. ananassae derived from natural populations which shows that chromosome arrangements may affect the mate recognition system in D. ananassae.

“…The most unusual feature of this species is spontaneous male meiotic recombination in appreciable frequency (Singh 2010b). It possesses high degree of inversion polymorphism, though only three paracentric inversions, namely subterminal alpha (2L), terminal delta (3L) and basal eta (3R), are found to be coextensive with the species (Singh 1996).…”

Section: Introductionmentioning

confidence: 99%

Origin of sexual isolation in Drosophila ananassae due to founder effects

Nanda

2011

Genetica

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The origin of sexual isolation is the central event in the evolution of biological species and plays a key role in maintaining biological diversity. Three mass culture stocks of D. ananassae originating from different geographic localities showing no isolation with each other were subjected to different degrees of bottlenecks i.e. one pair, five pairs and ten pairs. These drift lines were passed through flush-crash cycle at every generation with same initial number of founders, and maintained for twenty-seven generations and then the pattern of matings was tested among these nine drift lines involving 36 crosses in total. In 23 of 36 crosses, the difference between homogamic and heterogamic matings was significant and isolation indices were significantly more than zero in one direction only providing evidence for asymmetrical sexual isolation. Further, when Bonferroni test for pair-wise analysis was employed, significant differences between homogamic and heterogamic matings were found in 25 crosses. These findings provide evidence for origin of sexual isolation by founder effects in D. ananassae.