Patterns of Heat Stability Polymorphism at Acph Locus in Indian Natural Populations of Three Drosophila Species

Parkash, Ravi,Sharma, Manju,Sharma, Suman 한국유전학회 1991 Genes & Genomics Vol.13 No.4

Isofemale lines derived from Indian natural populations of Drosophila ananassae, D. takahashii and D. nepalensis were analysed through horizontal starch gel electrophoresis as well as post-electrophoretic heat denaturation technique for genetic variation at acid phosphatase locus. Allozymic data revealed nearly uniform patterns in D. takahashii and D. nepalensis populations while latitudinal variation was observed in D. ananassae. The contrasting patterns of allozymic variation in three Drosophila species concur with the niche-width variation hypothesis.

Climate warming mediates range shift of two differentially adapted stenothermal Drosophila species in the Western Himalayas

Ravi PARKASH,Seema RAMNIWAS,Babita Kajla 한국응용곤충학회 2013 Journal of Asia-Pacific Entomology Vol.16 No.2

The average temperature of the earth has increased from 0.3 to 0.6 °C, and warming is facilitating faunal reshuffling. Variable thermal environments warrant mechanisms to adjust the expression of phenotypic values to environmental needs. Ectothermic Drosophilids are profoundly affected by thermal selection (i.e., genetic effects)or through induced effects on phenotypes (i.e., plastic effects). Climatic data for the last fifty years involves a significant change in average temperature (Tave) ofWestern Himalayas,which has affected the distribution and boundaries of various Drosophilids in this region. There is a significant decline in the number of D. nepalensis from lower ranges; whereas D. ananassae is reported to be introduced to lower tomid mountainous ranges. Further, a comparison of fecundity, hatchability, and viability at different growth temperatures has shown significant decrease in trait values at 17 °C in D. ananassae and at 25 °C in D. nepalensis. Thus, the recent range changes of these two species involve genetic effects on ecophysiological and plastic effects on life history traits. Our results indicate that thermal plasticity of life history traits can be species-specific; thus climate change may lead to a mismatch of such traits to the changing environment. We suggest that D. nepalensis and D. ananassae could serve as indicator species for analyzing range changes under changing climatic conditions. Evolutionary biologists can provide unique perspective to the examination of how climate change will affect the earth's biota.

ADH Polymorphism and Ethanol Tolerance in Some Drosophila Species from India

Parkash, Ravi,Sharma, Manju,Sharma, Suman 한국유전학회 1992 Genes & Genomics Vol.14 No.3

Seven Indian geographical populations of D. melanogaster and ten oriental Drosophila species were assayed electrophoretically for Adh genie variation. Except four Drosophila species, most species revealed monomorphism or occurrence of one most frequent (>96%) and one rare allele. The Indian geographical populations of D. melanogaster revealed significant clinal variation (3% for 1˚latitude) at Adh locus and Adh^F allelic frequency correlated significantly with increase in latitude. It was suggested that the abundance of secondary alcohols in the southern Indian tropical and humid environment might exert selective pressure favouring higher frequency of Adh^S allele. Patterns of ethanol utilisation as well as ethanol tolerance were analysed in larval and adult individuals of seven geographical populations of D. melanogaster and three Drosophila species. The D. melanogaster populations revealed latitudinal variation in ethanol tolerance along north-south axis while other Drosophila species showed interspecific divergence of ethanol tolerance levels. The parallel occurrence of latitudinal variation at Adh locus as well as ethanol tolerance in Indian geographical populations of D. melanogaster could be maintained by balancing natural selection varying spatially along the north-south axis of the Indian sub-continent.

Allozymic Polymorphism in Indian Colonising Natural Populations of Zaprionus Indianus

Parkash, Ravi,Yadav, J P 한국유전학회 1992 Genes & Genomics Vol.14 No.4

Twelve Indian natural populations of Z. indianus. collected along 22˚latitudinal range, were analysed electrophoretically for allozymic variation of seven gene-enzyme systems. Interestingly all the seven Est loci were found to be highly polymorphic in all the populations of Z. indianus. Except Mdh-2 all the fourteen loci revealed extensive polymorphism. The Indian continental populations of Z. indianus revealed higher genetic similarities on the basis of Nei's genetic indices. The genetic structure of Z. indianus populations were characterised by significantly higher values of genetic indices as compared with other sympatric colonising Drosophila species from India; extensive inter-populational genotypic as well as allelic frequency heterogeneity; and higher genic differentiation at all the loci. All the polymorphic loci in geographical populations of Z. indianus revealed latitudinal clines and changes in allelic frequencies were found to correlate with latitude. The patterns of genie differentiation in Z. indianus population were comparable to those of D. melanogaster populations from India and other continents. The occurrence of higher genetic variability in Z. indianus populations were in agreement with its habitat generalist or broad niche-width characteristics i. e. the species populations utilised diverse food resources and displayed adaptation to variable climatic conditions. Thus, the observed genic divergence patterns in colonising populations of Z. indianus could be maintained by balancing natural selection varying spatially along the north-south axis of the Indian sub-continent.

Allozymic Polymorphism in Indian Natural Populations of Drosophila Melanogaster

Ravi Parkash,Suman Sharma,Shamina 한국유전학회 1993 Genes & Genomics Vol.15 No.3

Allozymic variation of seven gene-enzyme systems were analysed in eight Indian natural populations of D.melanogaster collected alnog 22˚ latitudinal range. Acph, Mdh-2 and five esterase loci revealed monomorphism while the other loci were found to be highly polymorphic in all the Indian populations of D.melanogaster. The genetic structures of D.melanogaster populations were characterised by extensive inter-populational genotype as well as allelic frequency heterogeneity; higher genie differentiation at six polymorphic loci; and allelic frequencies were found to correlate with latitude. The patterns of genie differentiation in D.melanogaster populations were comparable to those of populations from other continents. The occurrence of higher genetic variability in D.melanogaster populations was found to be in agreement with its habitat generalist or broad niche-width characteristics. The observed genie divergence patterns at six loci in the populations of D.melanogaster seemed to be maintained by balancing natural selection varying spatially along the north-south axis of the Indian sub-continent.

Latitudinal Differentiation in Alcoholic Utilisation and Desiccation - Starvation Tolerance in Drosophila Kikkawai Populations from India

Parkash, Ravi,Vandna 한국유전학회 1994 Genes & Genomics Vol.16 No.3

Indian geographical populations of D. kikkawai, collected along 20˚N latitudinal range, revealed significant genetic divergence not only of ethanol and acetic acid utilisation but also dessication and starvation tolerance. Latitudinal patterns of ethanol utilization (2.60 to 4.15%) and significantly higher acetic acid utilization (3.50 to 5.25%) were observed in adult individuals of seven geographical populations of D. kikkawai. Very low concentrations (upto 1%) of n-propanol and isopropanol served as resources while secondary alcohols were found to be toxic to D. kikkawai. populations. Thus, the northern and southern populations of D. kikkawai revealed divergence in the patterns of resource utilisation. The parallel occurrence of latitudinal genetic divergence for ethanol and acetic acid utilisation and for propanols in Indian populations of D. kikkawai could be maintained by balancing natural selection varying spatially along the north-south axis of the Indian subcontinent. The observed genetic differentiation in desiccation(17 to 26 hrs) as well as starvation tolerance (92 to 129 hrs) in D. kikkawai populations suggest the role of climatic selection along the latitudinal transect.

Utilisation of Alcoholic Resources in Five Colonising Drosophilids from Himachal Pradesh , India

Parkash, Ravi,Vandna 한국유전학회 1994 Genes & Genomics Vol.16 No.3

Drosophila melanogaster, Zaprionus indianus and D. repleta revealed significantly higher ethanol and acetic acid tolerance levels as compared with D. kikkawai and D. immigrans. The parallel patterns of utilisation of other primary and secondary alcohols seem to be correlated with the concentrations of these metabolites found in natural food resources. The longevity effects of n-butanol (0.4 to 1.5%) were found to be significantly high in all the five drosophilids as compared to 2-butanol. The interspecific differences for resource utilisation are in agreement with niche-width hypothesis and seem to be adaptively maintained by natural selection mechanisms.

Starvation and Desiccation Tolerance in Indian Populations of Drosophila Melanogaster

Ravi Parkash,Shamina,Neena 한국유전학회 1993 Genes & Genomics Vol.15 No.3

Data on mean survival times for starvation tolerance under highly wet conditions and desiccation tolerance at zero percent humidity revealed significant differences for four Indian geographical populations of D.melanogaster. The genetic control of these physiological traits was ascertained from the occurrence of little differences between two successive generations of various isofemale lines of D.melanogaster populations. The north Indian populations of D.melanogaster revealed significant higher tolerance for desiccation as compared with the southern populations. On the contrary, for starvation tolerance, under humid conditions, the survival values of the southern populations were found to be significantly higher than that of north Indian populations. It can be argued that the south Indian populations of D.melanogaster which lived in a hot and humid environment throughout the year were poorly protected against desiccation but displayed higher starvation tolerance due to steady metabolic rate at increased ambient temperature. Thus. Indian geographical populations of D.melanogaster revealed adaptively maintained genetic divergence for starvation and desiccation tolerance.

Allozyme Phylogeny of Five Species of Takahashii Species Subgroup of Drosophilla

Parkash, Ravi,Jyoutsna,Vandna 한국유전학회 1994 Genes & Genomics Vol.16 No.3

Allozymic variations at eight polymorphic loci in five species belonging to takahashii species subgroup were analysed through horizontal starch gel electrophoresis. Phylogenetic relationships based on NEI's as well as NAIR's indices revealed two main lineages. In one of the lineage, D. paralutea and D. prostipennis constitute one group while other main lineage includes two closely related species i. e. D. takahashii and D. lutescens and one distantly related species i. e. D. nepalensis. Thus, observed phylogenetic relationships based on allozymic data concur with the interrelation based on interspecific hybridization tests. The extent of observed allozymic divergence among five specis of takahashii subgroup seem to be correlated with their allopatric and endemic geographical distribution pattern throughout the oriental region.

Allozyme Variation in Ten Indian Natural Populations of Drosophila Immigrans

Parkash, Ravi,Yadav, J P 한국유전학회 1991 Genes & Genomics Vol.13 No.4

Ten Indian natural populations of D. immigrans, collected along 12˚ longitudinal and 6˚latitudinal ranges, were analysed electrophoretically for allozymic variation of eight gene-enzyme systems. Adh, α-Gpdh, Sod and three Est loci were found to be monomorphic, Mdh locus revealed some geographical variation while overall patterns of genie variation at six other polymorphic loci depicted similarities. Nei's significantly higher values of genetic similarities between populations pairs and low values of Wright's fixation index (F_(ST)) revealed that Indian populations of D. immigrans are genetically homogeneous for the loci analysed. Such observations are consistent with narrow nich-width in terms of food resources and climatic adaptation of this species. However, statistical analysis of allopatric populations of D. immigrans suggest genic differentiation at most polymorphic loci. The available data on genetic structure of D. immigrans populations could be explained on the basis of migration as well as balancing natural selection mechanisms.