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

Abstract

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.

Chromosomal Thermal Index: a comprehensive way to integrate the thermal adaptation ofDrosophila subobscurawhole karyotype

“…D. subobscura in particular (Balanyà et al 2009or Dolgova et al 2010 This index can be also used in other Drosophila species where adaptive inversions are or could be related to temperature as in the case of D. robusta (Levitan 1992(Levitan , 2003Levitan and Etges 2005), D. melanogaster (Lemeunier and Aulard 1992), D. guarani group (Brncic 1953) D. repleta group (Wasserman 1992), Hawaiian Drosophila species (Carson 1992), D. ananassae and other Indian species (Singh 2015). Even in the future, D r a f t thermal adaptive inversions could be detected due to the intensive research on chromosomal inversions in different organisms (Pennisi 2017).…”

Transposable elements in Drosophila

“…The Drosophila genus is estimated to include several thousand species [13] sharing their most recent common ancestor~25-40 My ago [14]. So far,~1500 drosophilid species have been described.…”

A resource on latitudinal and altitudinal clines of ecologically relevant phenotypes of the Indian Drosophila

“…As in several other taxonomic groups, the genus Drosophila is species-rich in India, presumably due to the extensive heterogeneity in ecological conditions. This environmental heterogeneity may have spurred diversification among populations and taxa, and many species in this genus are endemic to the Indian subcontinent 6 .…”