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

Journal of Asia-Pacific Entomology 16 (2013) 147–153

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Climate warming mediates range shift of two differentially adapted stenothermal Drosophila species in the Western Himalayas Ravi Parkash, Seema Ramniwas ⁎, Babita Kajla Department of Genetics, Maharshi Dayanand University, Type IV / 35, M.D.U., Campus, Rohtak-124001, India

a r t i c l e

i n f o

Article history: Received 25 February 2012 Revised 21 December 2012 Accepted 26 December 2012 Keywords: Temperature increase Drosophila nepalensis Drosophila ananassae Relative abundance Life history traits

a b s t r a c t 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) of Western 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 to mid 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. © Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society, 2013. Published by Elsevier B.V. All rights reserved.

Introduction Climate warming over the last quarter century is quite large in tiny fruit flies, butterflies and other insect taxa. In species of fruit fly, the frequencies of inversions were observed decades ago to correspond to the latitude and/ or altitude at which the flies were found (Rank and Dahlhoff, 2002; Umina et al., 2005). The biological effects of climate change have shown up primarily in ecological patterns, such as the northerly spread of species (Bakkenes et al., 2002; Hill et al., 2002; Skov and Svenning, 2004) or the onset of flowering of plants (Sparks et al., 2000; Fitter and Fitter, 2002; Miller-Rushing et al., 2006) and reproductive success of animals (Stevenson and Bryant, 2000; Visser and Holleman, 2001; Coppack and Both, 2002; Sanz et al., 2003). Due to climate warming, many insect species have shifted their ranges to higher latitudes and altitudes (reviewed by Hill et al., 2011). Recent global climate warming has caused species to shift their ranges poleward (Parmesan et al., 1999; Parmesan and Yohe, 2003). Insects, especially those species that have narrow thermal tolerances (Addo-Bediako et al., 2000; Deutsch et al., 2008) are particularly sensitive to temperature

⁎ Corresponding author. Tel.: +91 8930787521. E-mail addresses: [email protected], [email protected] (S. Ramniwas).

changes. There is now a substantial literature documenting that insects are expanding at their high-latitude and high-elevation cool range margins (Parmesan et al., 1999; Warren et al., 2001; Parmesan and Yohe, 2003; Hickling et al., 2006; Anderson et al., 2008) and retracting at their low-latitude and low-elevation warm margins (Wilson et al., 2005; Franco et al., 2006; Parmesan, 2006; Anderson et al., 2008). Many studies have focused on how insects respond to climate changes (Cammell and Knight, 1992; Harrington and Stork, 1995; Butterfield and Coulson, 1997; Bale et al., 2002; Chown and Terblanche, 2006); and much has been learned on specific insect taxa (Harrington et al., 1995; Parmesan et al., 1999; Hill et al., 2001; Reemer et al., 2003; Hickling et al., 2005). Corroborating the previous findings with genetic studies is more of an exception in the fruit fly, particularly Drosophila subobscura, a native of Europe which presents challenges as the necessary data do not extend far back. The result of Balanya et al. (2006) suggests that flies, with their short generation time, can cope genetically with climate change, whereas longer-lived organisms, such as large trees, are unlikely to be as flexible. Current efforts to study the biological effects of global change have focused on ecological responses, particularly shifts in species ranges. Genetic change may be at least as important as ecological ones in determining species' responses. In addition, such change may be a sensitive indicator of global changes that will provide different information than that provided by range shifts. Species can respond to climate change in three possible ways: (i) in order to track climate change, species can change or reshuffle their geographical

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R. Parkash et al. / Journal of Asia-Pacific Entomology 16 (2013) 147–153

hatchability, and viability at 21 °C, as compared with 17 °C. In this cold sensitive species, lower limits of thermal range (17 °C) significantly affect fitness traits.

Material and methods Collections Temperature average (Tave) over the last 50 years in the Western Himalayan regions is shown in Fig. 1A. Climatic data for Western Himalayan regions were obtained from the Indian Institute of Tropical Meteorology (IITM; www.tropmet.res.in). Wild individuals of Drosophila species (n =200–250) were collected from localities along an altitudinal gradient (219 m–1440 m) of the Indian subcontinent. The collections were made in winter (Nov–Jan) and spring (Feb–March) with net sweeping and bait traps from fruit markets and warehouses in 2004– 05 (Rajpurohit et al., 2008a, 2008b). Percent species distribution was estimated as the number of individuals of Drosophila species divided by the total number of individuals of all the different Drosophila species in the samples collected from a given locality. For laboratory analyses, 20 isofemale lines per population were set up from wild-caught females of

A

14.0

Western Himalayas 13.2

Taverage (º C)

distribution; (ii) may adapt to new environment either behaviorally, as in phenological shifts (timing of growth, reproduction, etc.), acclimation, or hardening; or genetically, such as by increasing heat tolerance; and (iii) may go extinct if unable to adapt. Temperature has a direct influence on many life history parameters of insects (Angilletta et al., 2002; Walther, 2002; Hanna and Cobb, 2007; Tewksbury et al., 2008). A large number of studies have been conducted over the past 20–30 years to investigate the effects of predicted scenarios of climate warming on insects (Hill et al, 2002; Wilson et al, 2005; Deutsch et al, 2008). Much of this research has focused on the effects of increase in summer temperature of 1–2 °C on rate-based processes of experimental populations, and mainly in polar and temperate climates (Parmesan et al., 1999; Bale et al., 2000; Karban and Strauss, 2004; Musolin, 2007; Tewksbury et al., 2008), or by the monitoring of shifts in distributions that have been correlated with natural climate warming (Gutierrez et al., 2008). Also, while thermo tolerance has been an area of research interest (Block et al., 1990; Chown and Nicolson, 2004), there has been less focus on the life history parameters of insects, especially those living in the tropical areas, or on the proximity of their upper thermal limits to the current and future temperature regimes. It is known that relatively small increases in temperature may become lethal or sub-lethal for such species (Talekar and Shelton, 1993; Klok et al., 2004; Lapointe et al., 2009). Life-history plasticity is a large subject, and for a manageable study it is necessary to narrow the subject matter considerably. Consequently, we focus on plasticity shown in the three closely interrelated life-history traits: fecundity, hatchability, and viability. Life-history traits may be correlated in an absolute way, as with genetically correlated traits; or in a more flexible way, involving individuals adjusting their trait combination to the current environment — with such plasticity permitting a more adequate response to the changing environments. Plasticity may be adaptive or nonadaptive, and reaction norms (more specifically, a given aspect of them) may or may not qualify as adaptation, in the narrower historical sense, to a variable environment. However, the distinctions are not always straightforward (Newman, 1992; Gotthard and Nylin, 1995; Spitze and Sadler, 1996). D. nepalensis, described from Nepal (Himalayas) by Okada (1955), is a Himalayan endemic cold adapted species; whereas D. ananassae, initially described from Indonesia by Doleschall (1858), is a circumtropical species belonging to the ananassae subgroup of the melanogaster species group (Bock and Wheeler, 1972). Although cosmopolitan in distribution, D. ananassae is a warm adapted tropical species and has not been recorded from higher latitudinal and altitudinal localities. The distribution of this species is limited by its sensitivity to cold and desiccation stress (Parkash and Munjal, 1999). D. nepalensis has not been analyzed so far for different quantitative traits conferring adaptation to harsh climatic conditions in the Himalayas. The effects of climate change in the Western Himalayan regions have resulted in significant demographic changes in Drosophilids (Kolli et al., 2006; Rajpurohit et al., 2008a), but there is paucity of data on life history traits which may be associated with the northern border limits of the Drosophila species. Some species have restricted distribution with clear borders on different continents, and range expansions have been reported in few cases (Jenkins and Hoffmann, 1999; Hoffmann et al., 2003). However, it is not clear why species distributions are limited. We examined the issue of the effects of global change, emphasizing the plastic effects on life history of two differentially adapted Drosophila species. We look at this issue with few questions in evolutionary biology: (a) Is plasticity adaptive for all species? (b) How important is the plasticity of life history traits in determining the geographical range of a species? To better understand these questions, one must compare traits at different growth temperatures. D. ananassae and D. nepalensis showed significant plastic effects for life history traits. Trait values decreased significantly at 25 °C for D. nepalensis. On the other hand, adaptive invasion of D. ananassae to low- and mid-altitude localities can be explained on the basis of significant plastic changes (3 fold high) in fecundity,

12.4

11.6

10.8

10.0 1950

1960

1970

1980

1990

2000

2010

Years

B

80 D. nepalensis r = - 0.98 ± 0.13***

60

% Distribution

148

40

20

D. ananassae y = 0.98 ± 0.09***

0 1960

1980

2008

Years Fig. 1. Regression slope for increase in Tave during the past five decades for the Western Himalayan region (A); and (B) changes in % distribution of D. nepalensis and D. ananassae in collections made in 1960s, 1980s, and 2000s in a midland locality (Solan).

R. Parkash et al. / Journal of Asia-Pacific Entomology 16 (2013) 147–153

both species, and all the experiments were performed with G1 and G2 generations. The density (60–80 flies per vial) was controlled by limiting the egg laying period (6–8 h) on the usual Drosophila food (i.e. cornmeal–yeast–agar medium). For all populations, replicate cultures of isofemale lines were grown at 17, 21, and 25 °C. The border populations of D. nepalensis (Rohtak and Chandigarh) and D. ananassae (Solan) in the foothills of Western Himalayas have undergone extensive changes due to global warming, changes in seasonal timings, and local effects (deforestation and industrialization) during the last 3–4 decades. Thus, the changes in the distribution of D. nepalensis and D. ananassae for the three data-set collections (1960s, 1980s, and 2000s) were compared on the basis of dominance index as well as relative abundance. These indices were calculated using the frequencies of species individuals collected from all the collection sites. Relative abundance (RA) of the species was estimated as the number of individuals of the species divided by the total number of individuals in the sample. Dominance index (DI) was calculated as: DI = ni (ni − 1) / N (N − 1); where ni is number of individuals of the species i, and N is the total number of the samples (Simpson, 1949). Analyses of traits Life history traits (fecundity, hatchability, and viability) were estimated in isofemale lines from populations of both species. For estimating fecundity, each mated pair was aspirated and placed in an oviposition chamber for a 24 hour mating period; thereafter, the male was removed. The numbers of eggs laid by each female (during 24 h) at the replaceable bottom plate of the oviposition chamber were daily recorded. This was followed for 15 successive days (7th to 21st), as this period coincided with the highest egg production; and the data were shown as daily fecundity. For hatchability, the eggs were placed on a small squarish black paper (moistened with 70% ethanol), which was kept on the food surface in a vial. The numbers of hatched eggs were counted under the microscope. Viability was estimated as a ratio of adult flies eclosed from the number of hatched eggs. Statistical analyses For all traits in each population, the isofemale line means (n = 20) and population means (n = 20 isofemale lines ∗ 10 individuals each) ± SD were used for illustration and tabular data. Since all the traits showed higher repeatability values across generations, data were pooled. Regression analysis was made for association of percent species distribution and relative species abundance with climatic (Tave) and geographic (altitude) variables. Results Changes in species distribution Data on the three sets of collections over the last 40 years in localities which represent northern species border for D. nepalensis and D. ananassae are given in Table 1. The impact of climatic changes in the foothills of the Himalayan region is evident from significant reduction in winter duration (from 5 months in 1960s to 4 months in 2000s, and with the advance of spring timings), as well as effects of global warming (Rajpurohit et al., 2008a). D. ananassae is a cold sensitive species with chill-coma recovery time of 60 min (Rajpurohit et al., 2008b) as opposed to 4 min for the cold adapted species D. nepalensis. Thus, the absence of D. ananassae and the occurrence of D. nepalensis in 1960s from low to midland localities in the north match the colder climatic conditions at that time (Table 2). During about the last two and a half decades, D. ananassae has invaded foothills, as shown by field collections. The distribution of D. ananassae changed from 3.11% in 1980s to 14.87 % in 2008 (Table 2; Fig. 1B). The data on dominance index and relative abundance have also shown significant changes for this species

149

Table 1 Data on geographical and climatic variables over the last 30 years for the altitudinal sites of origin of D. nepalensis and D. ananassae populations. For D. nepalensis Rohtak was the marginal population and for D. ananassae marginal population is Solan. Population

Lat (°N)

Long (°E)

Alt (m)

Tave

% RH

Rohtak Chandigarh Parwanoo Chamba Solan

28.50 30.44 30.51 32.36 30.58

76.30 76.52 77.15 76.06 77.07

219 400 640 996 1440

25.24 24.13 24.65 22.21 19.55

69.52 68.21 66.31 61.00 55.50

(Table 2). These data represent pooled annual collections from a given locality. On the other hand, D. nepalensis has disappeared from foothills. The distribution of D. nepalensis declined from ~67% in 1960s to 2 % in 2008 in a mid altitudinal locality Solan, and retracted (% Distribution ~0) from low land localities (Fig. 1B). Moreover, this species is highly sensitive to heat stress (knockdown time ~1 min). Thus, D. ananassae invasion in the species border localities also corresponds to warming effects as well as reduction in winter duration; and the range retraction of D. nepalensis from lower to mid altitudes corresponds to increasing temperature due to changing climate.

Life history traits Results on the three life history traits (fecundity, hatchability, and viability) at three growth temperatures (17, 21, and 25 °C) for altitudinal populations of both species are shown in Table 3. For all traits, there are no clinal or geographical variations when trait values are compared either at 17 °C, 21 °C, or at 25 °C (i.e. common garden experiments). Thus, we may infer that genetic variability for these traits may be low. Alternatively, it may be possible that a lower number of isofemale lines analyzed in the present studies may not be adequate to uncover genetic differentiation for these traits. Interestingly, a comparison of data on life history traits across two growth temperatures has evidenced significant plastic effects (Table 3; Figs. 2A and B). For D. ananassae, in all the populations at 17 °C, there are significant reductions in fecundity, hatchability, and viability; i.e. trait values are about one third of those at 25 °C. Thus, low reproductive success of D. ananassae populations at 17 °C can limit this species from invading colder regions. In contrast a significant decrease in trait values were observed at the higher end; i.e. at 25 °C for D. nepalensis, such may have resulted in its retraction from the lowland localities. However, effects due to global warming may have favored reproductive success of one species (D. ananassae) and disfavored D. nepalensis at foothill localities in 2000s, as compared with 1960s when the climatic conditions in these regions were colder and humid.

Table 2 Data based on three sets of collections (1961–62, 1983–84, and 2007–08) of D. nepalensis (Dn) and D. ananassae (Da) for % distribution (% D), dominance index (DI) and relative abundance (RA). Winter duration of the sites of origin are also given. 1961–62 Dn %D DI RA Winter (months)

1983–04 Da

66.96 0.0 0.446 0.0 0.669 0.0 5 (Nov–Mar)

Dn

2007–08 Da

29.12 3.11 0.089 0.0007 0.089 0.034 4.5 (Nov–mid-March)

Dn

Da

2.40 14.87 0.0001 0.0193 0.0017 0.143 4.5 (mid-Nov– mid-March)

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Table 3 Data on population means (±S.E.) for fecundity, hatchability (%) and viability (%) for wild caught female flies from five altitudinal populations of D. nepalensis and D. ananassae. Population (alt. in m)

Fecundity (eggs/day) Dn

Da

Dn

Hatchability (%) Da

Dn

Da

Rohtak (219) Chandigarh (400) Parwanoo (640) Chamba (996) Solan (1440) m ± s.e. c.v. r ± s.e. (altitude)

21.23 ± 2.32 30.36 ± 4.20 34.21 ± 3.21 39.21 ± 2.98 44.25 ± 2.12 33.85 ± 2.10 25.87 0.99 ± 0.03

29.25 ± 2.21 26.25 ± 2.02 23.21 ± 1.98 18.25 ± 3.02 12.32 ± 2.14 21.85 ± 1.56 30.61 −0.99 ± 0.04

33.25 ± 2.14 40.31 ± 1.69 51.27 ± 2.23 60.15 ± 1.98 68.25 ± 1.58 50.61 ± 1.42 28.12 0.98 ± 0.05

41.12 ± 1.02 35.21 ± 2.12 32.60 ± 1.02 29.25 ± 1.31 25.36 ± 2.14 32.72 ± 2.30 18.24 −0.99 ± 0.04

37.56 ± 1.11 43.14 ± 2.36 46.25 ± 1.85 51.36 ± 1.97 54.25 ± 2.00 46.56 ± 2.31 14.28 0.99 ± 0.05

31.65 ± 2.00 29.02 ± 2.19 27.56 ± 1.87 23.25 ± 1.96 20.32 ± 2.36 26.36 ± 1.25 17.22 −0.97 ± 0.05

Climatic associations We observed clinal variation for species distribution in populations of D. nepalensis and D. ananassae. It is generally assumed that selection pressures due to climatic conditions are responsible for geographical differentiation in quantitative traits. For body melanization and desiccation resistance, we found parallel results for significant regression coefficients (slope values) as a function of change in altitude of origin as well as for climatic variables; i.e. Tave and RH (Table 4). Our results

Viability (%)

further support that there are correlated selection responses for these stress-related traits in D. ananassae. Further, for D. nepalensis, species distribution and species abundance are negatively correlated (r= −0.96± 0.03) with Tave of the localities of origin in the Western Himalayas (Table 2), while reverse trend was observed for D. ananassae (r= 0.94± 0.07). Thus, climate changes over long periods (50 years) have affected invasive ability of Drosophila species in the Western Himalayas. Discussion

A 100 D. nepalensis

Life history traits

80

Fecundity % Hatchability % Viability

60

40

20

0

17

21 Temperature ( °C )

25

B 100 D. ananassae

Life history traits

80

Fecundity % Hatchability % Viability

60

40

20

0

17

21 Temperature ( °C )

25

Fig. 2. Significant plastic effects of growth temperatures on three life history traits (fecundity, % hatchability, and % viability) in D. nepalensis (A) and D. ananassae (B) in Solan.

Since ectothermic insects face major challenges for adaptations to abiotic stresses, there is growing interest in the consequences of climate change on insect populations (Harrington and Stork, 1995). Due to climatic warming, there are shifts in Drosophila species distributions as well as genetic changes in quantitative traits. Widespread Drosophila species have shown that populations with increased levels of resistance evolve rapidly (Huey et al., 2000). By contrast, the genetic potential of a sensitive species to evolve in response to climate change is largely unknown. We are aware of two Australian rain forest species which have shown low potential for climatic stress adaptation; i.e. low variation for cold resistance has limited D. serrata, while there is lack of evolutionary potential for desiccation resistance in D. birchii (Jenkins and Hoffmann, 1999; Hoffmann et al., 2003). However, it is not known whether distributions of other tropical species are limited by similar genetic attributes at the species borders. On the Indian subcontinent, D. ananassae occurs abundantly at low altitudinal sites in the southern humid localities (Reddy and Krishnamurthy, 1974; Parkash and Munjal, 1999). By contrast, D. nepalensis is a cold specialist, stenothermal species with a physiology adapted to a narrow range of developmental temperatures. Collection surveys in 1960s did not encounter D. ananassae, whereas, D. nepalensis was found abundantly (~67%) in the foothills (low to mid altitudes) of the Western Himalayas (Parshad and Paika, 1964). However, demographic changes during the last two and a half decades match recent climatic warming in low to mid-altitudinal localities in the Western Himalayas (Table 2). A comparison of data on Tave and RH across the last fifty years corresponds to increase in ambient temperature and a decrease in humidity resulting in range changes of these species (www.tropmet.res.in). The climates of temperate regions are becoming increasingly hospitable to insect life, raising concerns about the behavior of indigenous species and about the risk of invasion by exotic species, which may result in disruption of normal ecosystem functions. Many temperate-zone insect species have shifted their distribution in response to recent climate change. Examples are the pine processionary moth (Thaumetopoea pityocampa) in Europe (Battisti et al., 2006), winter moth (Operophtera brumata) and autumnal moth (Epirrita autumnata) in Scandinavia (Jepsen et al., 2008), and southern pine beetle (Dendroctonus frontalis) in North America (Tran et al., 2007). Some species that have historically been constrained in the distribution by geographical barriers such as mountain ranges are likely to overcome these barriers and suddenly

R. Parkash et al. / Journal of Asia-Pacific Entomology 16 (2013) 147–153

151

Table 4 Simple regression analysis of changes in % distribution (% D) and relative abundance (RA) as a function of altitude and average temperature (Tave) of origin of populations of D. nepalensis (Dn) and D. ananassae (Da) in localities of Himalayan region. Altitude

%D RA

Dn Da Dn Da

Tave

R

b

R

B

0.89 ± 0.11 −0.94 ± 0.19 0.91 ± 0.09 −0.95 ± 0.13

0.010 ± 0.003*** −0.007 ± 0.001*** 0.0001 ± 0.00003*** −0.0001 ± 0.00001***

−0.97 ± 0.10 0.92 ± 0.07 −0.96 ± 0.09 0.97 ± 0.07

−1.72 ± 0.25*** 1.24 ± 0.09*** −0.01 ± 0.002*** 0.02 ± 0.001***

expand their range. For example, increased movements of warm air masses towards high latitudes have caused recent influxes of diamondback moth (Plutella xylostella) on the Norwegian islands of Svalbard in the Arctic Ocean, 800 km north of the edge of its current distribution in the western Russian Federation (Coulson et al., 2002). D. nepalensis and D. ananassae are stenothermal species and physiologically adapted to a narrow range of developmental temperatures. Thermal sensitivity has the potential to influence ecology and fitness of a species. Thus, the extent to which ectotherms can tolerate changes in their ambient thermal environments is critical in determining their distribution and abundance. Several investigations have shown the role of thermal plastic effects on quantitative traits for adaptations to temporal and spatial changes in climatic conditions (Willott and Hassall, 1998; Mousseau et al., 2000). In the present study, D. nepalensis and D. ananassae have shown significant plastic effects for life history traits. The evolutionary changes in these traits can be explained on the basis of climatic selection of trait variability. Since life history traits are dependent on thermal conditions, we compared fecundity, hatchability, and viability at three growth temperatures (17, 21, and 25 °C). In D. nepalensis, life history trait values are significantly reduced at 25 °C, which can limit its occurrence at higher temperatures. By contrast, in D. ananassae, life history trait values are greatly reduced at 17 °C, and this can limit its occurrence in colder habitats. Thus, due to global warming, the cold adapted species D. nepalensis has retracted from low to midland localities; and D. ananassae (warm adapted species) has invaded border localities (Fig. 3) as a consequence of reproductive plasticity. In conclusion, the observed range changes of D. nepalensis and D. ananassae have resulted as a consequence of plasticity in life history traits under global warming effects at the northern border limits.

Change in physiology, phenology and distribution of individual species will inevitably alter competitive and other interactions between species, with consequent feedbacks to local abundance and geographic range. Plasticity seems to provide a good way of adapting the phenotype, yet not all organisms are perfectly plastic. Various Drosophilids are distributed nearly throughout the globe, and changes in reproductive traits offer potential adaptations in different Drosophila species. Temperature differences are sufficiently pronounced in the various geographical regions. Hence, we might predict a positive correlation between life history traits and adaptation to different geographical regions. In the present study, we found that D. nepalensis, restricted to the much colder and dry regions of the Western Himalayas, shows non-adaptive plastic effects in accordance with increasing habitat temperature; whereas, D. ananassae is habitually found in warm and humid areas and has adaptive plastic effects for life history traits driving its range in montane localities. Phenotypic plasticity in Drosophilids is still insufficiently investigated but is relevant to understanding natural population ecology. Temperate and tropical species differ significantly in the thermal range at which they can develop under laboratory conditions. Further, phenotypic plasticity for life history traits are more detrimental in the cold adapted than in warm adapted species. The associations of life history traits with the environments suggest that such traits may present the adaptive characteristics underlying the diversification and distribution of Drosophila species. The present study suggests that Drosophila species respond to climate change by shifting their distribution range, changing in abundance, physiology, behavior, and community structure. With the information base and the currently available expertise, we can apply evolutionary knowledge to global change concerns. With this paper, we hope to stimulate efforts in the direction.

Fig. 3. Schematic representation of range changes in D. nepalensis and D. ananassae during the last five decades in localities of the Western Himalayas.

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Acknowledgments Financial assistance from the Council of Scientific and Industrial Research, New Delhi to Ravi Parkash [Emeritus Scientist Project no. 21(0847)11EMR-11] is gratefully acknowledged. The Department of Science and Technology, New Delhi is gratefully acknowledged for supporting the present research work through DST-INSA/INSPIRE Faculty fellowship (IFA-11LSBM-08). References Addo-Bediako, A., Chown, S.L., Gaston, K.J., 2000. Thermal tolerance, climatic variability and latitude. Proc. R. Soc. Lond. B 267, 739–745. Anderson, S., Conrad, K., Gillman, M., Woiwod, I., Freeland, J., 2008. Phenotypic changes and reduced genetic diversity have accompanied the rapid decline of the garden tiger moth (Arctia caja) in the U.K. Ecol. Entomol. 33, 638–645. Angilletta, M.J., Niewiarowski, P.H., Navas, C.A., 2002. The evolution of thermal physiology in ectotherms. J. Therm. Biol. 27, 249–268. Bakkenes, M., Alkemade, R.M., Ihle, F., Leemans, R., Latour, J.B., 2002. 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