Female remating inDrosophila ananassae: shorter duration of copulation during second mating as compared to first mating

Drosophila ananassae, a cosmopolitan and domestic species, belongs to theananassae subgroup of themelanogaster species group. Female remating was observed in ten mass culture stocks of this species, which were initiated from flies collected from different geographic localities. The frequency of female remating ranges from 24% to 56% in different strains. Strains show significant variation in remating latency (days). Significant variation has also been found in all the stocks for duration of copulation between first and second matings. The duration of copulation is shorter in second mating as compared to first mating inD. ananassae.     

Male Remating in Drosophila ananassae: Evidence for Interstrain Variation in Remating Time and Shorter Duration of Copulation during Second Mating

In Drosophila ananassae, male remating was studied using ten mass culture stocks which were initiated from flies collected from different geographic localities. Male remating occurs at a high frequency and varies within narrow limits (84-96 percent) in different strains. Interestingly, male remating time (in min) varies from 7.41 (Bhutan) to 21.59 (PAT) in different strains and the variation is highly significant. Further, the results also show that males copulate for shorter duration during second mating. This is the first report in the genus Drosophila which provides evidence for interstrain variations for male remating time as well as for shorter duration of copulation during second mating as compared to first mating in D. ananassae.     

Remating Behavior of Cnephasia jactatana Walker Females (Lepidoptera: Tortricidae)

Cnephasia jactatana Walker is an important pest of kiwifruit in New Zealand. We investigated, under laboratory conditions, the effects of multiple mating on the reproductive performance of C. jactatana females and how such effects varied with male virginity and larval nutrition. We found that in permanent pairs, remating increased female fecundity and fertility but suboptimally fed females benefited more from remating. Regardless of this benefit, mass-reared pairs had a lower remating frequency. Females remating with a virgin male or a male that had delivered a spermatophore presented similar fecundity and fertility; however, females receiving a second ejaculate from a virgin male had increased daily fecundity. Female weight clearly affected remating behavior since those that received a second ejaculate were significantly heavier. Neither mating length nor size of the first spermatophore influenced female remating. Further, mass-reared and individually reared males produced spermatophores of similar size.     

No Effect of Male Courtship Intensity on Female Remating in the Butterfly <Emphasis Type="Italic">Pieris napi</Emphasis>

In Pieris napi, female fitness increases with number of matings, but wild females mate at an unexpectedly low rate. From a sexual conflict perspective this could be because males manipulate female remating, or alternatively, because wild females experience costs associated with remating which are not applicable under laboratory conditions. To get an indication which sex controls remating and/or the different sexes’ relative costs and benefits of remating, we here test whether female mating frequency is affected by male courtship intensity. We found no effect on female mating frequency or lifespan. This indicates that (i) females control remating and their optimal mating frequency is lower compared to males, or (ii) males can manipulate female remating. We argue that both these alternatives may apply simultaneously to P. napiand that they are inseparable.     

Female Remating Behavior in a Lekking Moth

In polyandrous species, male reproductive success will at least partly be determined by males' success in sperm competition. To understand the potential for post‐mating sexual selection, it is therefore important to assess the extent of female remating. In the lekking moth Achroia grisella, male mating success is strongly determined by female choice based on the attractiveness of male ultrasonic songs. Although observations have indicated that some females will remate, only little is known about the level of sperm competition. In many species, females are more likely to remate if their first mating involved an already mated male than if the first male was virgin. Potentially, this is because mated males are less well able to provide an adequate sperm supply, nutrients, or substances inhibiting female remating. This phenomenon will effectively reduce the strength of pre‐copulatory sexual selection because attractive males with high mating success will be more susceptible to sperm competition. We therefore performed an experiment designed both to provide a more precise estimate of female remating probability and simultaneously to test the hypothesis that female remating is influenced by male mating history. Overall, approximately one of five females remated with a second male. Yet, although females mated to non‐virgin males were somewhat more prone to remate, the effect of male mating history was not significant. The results revealed, however, that heavier females were more likely to remate. Furthermore, we found that females' second copulations were longer, suggesting that, in accordance with theory, males may invest more sperm in situations with an elevated risk of sperm competition.     

Behavioral genetics of Drosophila ananassae

Drosophila ananassae has a unique status among Drosophila species because of certain peculiarities in its genetic behavior. The most unusual feature of this species is its relatively high frequency of spontaneous male recombination. The results of studies on non-sexual behavior, such as phototactic responses, eclosion rhythm, and preferences for oviposition and pupation sites, lead us to suggest that this behavior is under polygenic control, with a substantial amount of additive genetic variation. Sexual isolation has been reported in D. ananassae with the degree of such isolation being stronger in isofemale lines than in natural populations. The significant variations seen in the mating propensity of several isofemale strains, inversion karyotypes and wild type strains, the diminishing effects of certain mutations on the sexual activity of males, and the positive responses to selection for high and low mating propensity point to a genetic control of sexual behavior in D. ananassae. Males contribute more to variation and thus are more subject to intrasexual selection than females. There is a positive correlation between sternopleural bristle number, mating propensity and fertility in D. ananassae. This correlation between morphometric traits and mating success suggests that larger flies are more successful in mating than smaller ones. There is also evidence for adaptive plasticity and a trade-off between longevity and productivity in D. ananassae. Rare, specific courtship song parameters that provide males with a mating advantage have also been reported in different geographic strains of D. ananassae. The remating behavior of males and females, sperm displacement, and the bi-directional selection for female remating speed indicate that post-mating behavior in this species may also be under genetic control. The occurrence of size assortative mating further indicates that there is size-dependent sexual selection in D. ananassae.     

Population and behaviour genetics of Drosophila ananassae

Drosophila ananassae is a cosmopolitan and domestic species. It occupies a nuique status among the Drosophila species due to certain peculiarities in its genetic behaviour. The most unusual feature of this species is spontaneous male recombination in appreciable frequency. The present review summarises the work done on population and behaviour genetics of D. ananassae from India. Population dynamics of three cosmopolitan inversions has been studied in Indian population of D. ananassae and it is evident from the results that there is a considerable degree of genetic divergence at the level of inversion polymorphism. In general, the populations from south India show more differentiation than those from the north. These three cosmopolitan inversions, which are coextensive with the species, exhibit heterosis. Interracial hybridization does not lead to beaakdown of heterosis, which suggests that evidence for coadaptation is lacking in geographic populations of D. ananassae. Heterosis appears to be simple luxuriance rather than populational heterosis (coadaptation). Unlinked inversions occur in random associations, indicating no interchromosomal interactions. However, two inversions of the third chromosome often show strong linkage disequilibrium in laboratory populations, which is due to epistatic gene interaction and suppression of crossing-over. Genetic variations for certain allozyme polymorphism and sternoleural bristle phenotypes in Indian populations of D. ananassae have also been observed.A number of investigations have also been carried out on certain aspects of behaviour genetics of Indian D. ananassae. There is evidence for sexual isolation within D. ananassae. Significant variations in mating propensity of several isofemale strains, inversion karyotypes, the diminishing effects of certain mutations on sexual activity of males and positive response to selection for high and low mating propensity provide evidence for genetic control of sexual behaviour in D. ananassae. Males contribute more to variation and thus are more subject to intra-sexual selection than females. Evidence for rare male mating advantage has also been presented. Geographic strains of D. ananassae show variation with respect to oviposition site preference. The results of studies on pupation site preference, which is an important component of larval behaviour, suggest that larval pupation behaviour in D. ananassae is under polygenic control with a substantial amount of additive genetic variation.     

Water Availability Affects Female Remating in the Seed Beetle,Callosobruchus chinensis

Benefits of multiple mating to females may come from the acquisition of water in male ejaculates. This hypothesis seems plausible in species in which males provide females with large ejaculates and has been tested with the prediction that females mate more frequently when an external source of water is unavailable. My study observed that females deprived of water were more likely to remate than females given water in the adzuki bean beetle, Callosobruchus chinensis. This result suggests that females may absorb the water in male ejaculates and thus change their remating receptivity according to the need for additional water. However, compared with related species, the ejaculate size is smaller, so ejaculatory hydration benefits are expected to be small in this species. There were no significant differences in lifetime fecundity and longevity between females that were allowed to receive one ejaculate from remating and females that were not allowed to do so when water was unavailable. This provides no evidence that receiving an additional ejaculate enhances female fitness. Thus, obtaining water from male ejaculates may partly compensate the costs of remating to females, although it alone would be insufficient to explain polyandry in C. chinensis. Increased mating frequency in water‐deprived females would not necessarily support the hypothesis that females remate for ejaculatory hydration benefits.     

Effect of chromosome arrangements on mate recognition system leading to behavioral isolation in <Emphasis Type="Italic">Drosophila ananassae</Emphasis>

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.     

Female Age Determines Remating Behavior in Wild Mexican Fruit Flies

Male and female age are important factors that can influence mating and remating behavior. Females can discriminate against or prefer older males, but there have been relatively fewer studies on how female and male age influence female remating. Here we showed in wild flies of the Mexican fruit fly Anastrepha ludens (Loew), that when females were given a choice between males of different ages, younger females preferred to mate with younger males over older males, while older females were less selective. Also, when given a choice between males of different ages, older females had longer copulation durations than younger females. On the other hand, older males and females had lower mating success, compared with young and middle-aged flies under no choice conditions. However, middle-aged females mated faster compared to young females and young males mated faster compared to middle-aged males. Male age did not influence female remating, while female age strongly determined female remating, with no females remating when they were old. It is unclear if female receptivity mechanisms are switched off at older ages, or if females are reluctant to remate due to possible costs of mating. We discuss our results in terms of how male and female age can influence mating decisions.     

Interpopulation variation in female remating is attributable to female and male effects in <Emphasis Type="Italic">Callosobruchus chinensis</Emphasis>

The evolution of female multiple mating is best understood by consideration of male and female reproductive perspectives. Females should usually be selected to remate at their optimum frequencies whereas males should be selected to manipulate female remating to their advantage. Female remating behavior may therefore be changed by variation of male and female traits. In this study, our objective was to separate the effects of female and male strains on female remating for the adzuki bean beetle, Callosobruchus chinensis, for which there is interstrain variation in female remating frequency. We found that interstrain variation in female remating is primarily attributable to female traits, suggesting genetic variation in female receptivity to remating in C. chinensis. Some interstrain variation in female remating propensity was attributable to an interaction between female and male strains, however, with the males of some strains being good at inducing nonreceptivity in females from one high-remating strain whereas others were good at inducing copulation in nonvirgin females from the high-remating strain. There is, therefore, interstrain variation in male ability to deter females from remating and in male ability to mate successfully with nonvirgin females. These results suggest that mating traits have evolved along different trajectories in different strains of C. chinensis.     

Climate change,boundary increase and elongation of a pre‐existing cline: A case study in Drosophila ananassae

During the past two to three decades, Drosophila ananassae, a warm adapted tropical species, has invaded low to mid altitude localities in the western Himalayas. Due to its cold sensitivity, this species had never been recorded from higher latitudes as well as altitudes in India to the 1960s. A latitudinal cline in this desiccation‐sensitive species corresponds with southern humid tropical localities rather than northern drier subtropical localities. An extension of its cline into lowland to midland montane localities has resulted due to global climatic change as well as local thermal effects through anthropogenic impact. However, D. ananassae populations at species borders are characterized by lower genetic variability for body melanization as well as for desiccation resistance. There is a lack of thermal plastic effects for body melanization, and the observed extended cline might represent evolutionary (genetic) response due to selection pressure imposed by drier habitats. A comparison of fecundity, hatchability and viability at three growth temperatures (17, 20 and 25°C) showed significant reduction in trait values at 17°C in D. ananassae. Thus, its recent range expansion into northern montane localities might involve genetic effects on stress‐related traits and plastic effects on life history traits. We suggest that D. ananassae could serve as an indicator species for analyzing range expansion under changing climatic conditions.     

Remating inhibition in the melon fly,Bactrocera (=Dacus) cucurbitae (Diptera: Tephritidae): Copulation with spermless males inhibits female remating

Eight hour copulation of the melon fly,Bactrocera cucurbitae, which usually mates at dusk and finishes copulation at dawn, inhibited female remating, while 3 h copulation did not. Copulation of females with either normal or virgin sterile males inhibited female remating. Sperm-depleted sterile males inhibited female remating at the same rate as normal males when the copulation duration was 8 h, indicating that existence or amount of sperm in females' spermathecae is not important in remating inhibition. Females of a wild strain remated later than females of a mass-reared strain, irrespective of strains of 1st and 2nd males. This suggests that the females may control their own remating, or that there is a difference between wild and mass-reared strains in their sensitivity to a male substance that inhibits females' receptivity.     

Simulating natural light and temperature cycles in the laboratory reveals differential effects on activity/rest rhythm of four Drosophilids

Recent studies under semi-natural conditions have revealed various unique features of activity/rest rhythms in Drosophilids that differ from those under standard laboratory conditions. An additional afternoon peak (A-peak) has been reported for Drosophila melanogaster and another species D. malerkotliana while D. ananassae exhibited mostly unimodal diurnal activity. To tease apart the role of light and temperature in mediating these species-specific behaviours of four Drosophilid species D. melanogaster, D. malerkotliana, D. ananassae, and Zaprionus indianus we simulated gradual natural light and/or temperature cycles conditions in laboratory. The pattern observed under semi-natural conditions could be reproduced in the laboratory for all the species under a variety of simulated conditions. D. melanogaster and D. malerkotliana showed similar patterns where as D. ananassae consistently exhibited predominant morning activity under almost all regimes. Z. indianus showed clearly rhythmic activity mostly when temperature cycles were provided. We find that gradually changing light intensities reaching a sufficiently high peak value can elicit A-peak in D. melanogaster, D. malerkotliana, and D. ananassae even at mild ambient temperature. Furthermore, we show that high mid-day temperature could induce A-peak in all species even under constant light conditions suggesting that this A-peak is likely to be a stress response.     

Temperature sensitivity of circadian clocks is conserved across Drosophila species melanogaster,malerkotliana and ananassae

Light and temperature are the major environmental cycles that can synchronize circadian rhythms in a variety of organisms. Previously, we have shown that under light/dark cycles of various photoperiods, the Drosophila species ananassae exhibits unimodal activity pattern with a prominent morning activity peak in contrast with Drosophila melanogaster and Drosophila malerkotliana, which show bimodal activity pattern with morning and evening activity peaks. Here we report that circadian clocks controlling activity/rest rhythm of these two less-studied species D. malerkotliana and D. ananassae can be synchronized by temperature cycles and that even under temperature cycles D. ananassae exhibits only a pronounced morning (thermophase onset) activity peak. Although D. melanogaster and D. ananassae exhibit differences in the phase of activity/rest rhythm under temperature cycles, circadian clocks of both show similar sensitivity to warm temperature pulses. Circadian period of activity/rest rhythm of D. ananassae differs from the other two species at some moderate-range temperatures; however, in conditions that are more extreme, circadian clocks of D. melanogaster, D. malerkotliana and D. ananassae appear to be largely temperature compensated.     

Remating and sperm displacement in a natural population of Drosophila buzzatii inferred from mother-offspring analysis of microsatellite loci

Prospects for estimation of parameters of models of sperm competition from field data have improved recently with the development of methods that employ multilocus genotype data from brood-structured samples. Sperm competition in Drosophila buzzatii is of special interest because it is possible to directly observe the breeding behaviour of this species in its natural habitat of rotting cactus. Previous laboratory experiments showed that this species exhibits an unusual pattern of frequent remating and sperm partitioning. This paper reports the first attempt to estimate the frequency of female remating and sperm competition in natural populations of D. buzzatii. For the Australian population studied, the mean remating frequency was lower (alpha = 2.12-2.20) than previously estimated in laboratory experiments with the same population, whereas mean sperm displacement (beta = 0.69-0.71) fell within the limits of previous laboratory results. The evolution of the D. buzzatii mating system is discussed.     

Effects of Temperature,Photoperiod, and Light Intensity on the Eclosion Rhythm of the High-Altitude Himalayan Strain of Drosophila ananassae

Eclosion rhythm of the high-altitude Himalayan strain of Drosophila ananassae from Badrinath (altitude 5123 m) was temperature-dependent and at 21°C, it was entrained by cycles of 12 h light: 12 h darkness (LD 12:12) and free-ran in constant darkness, however, it was arrhythmic at 13°C or 17°C under identical experimental conditions (Khare, P. V., Barnabas, R. J., Kanojiya, M., Kulkarni, A. D., Joshi, D. S. (). Temperature dependent eclosion rhythmicity in the high altitude Himalayan strains of Drosophila ananassae. Chronobiol. Int. 19:1041–1052). The present studies were designed to see whether or not these strains could be entrained at 13°C, 17°C, and 21°C by two types of LD cycles in which the photoperiod at 100 lux intensity varied from 6 h to 18 h, and the light intensity of LD 14:10 cycles varied from 0.001 lux to 1000 lux. All LD cycles entrained this strain at 21°C but not at 13°C or 17°C. These results demonstrate that the entrainment of eclosion rhythm depends on the ambient temperature and not on the photoperiod or light intensity of LD cycles. Thus the temperature has taken precedence over the light in the entrainment process of eclosion rhythm of the high altitude Himalayan strain of D. ananassae. This may be the result of natural selection in response to the environmental temperature at Badrinath that resembles that of the sub-Arctic region but the photoperiod or light intensity are of the subtropical region.     

Fluorescence patterns of heterochromatin in mitotic and polytene chromosomes in seven members of three sub-groups of the melanogaster species group of Drosophila

A comparative study of fluorescence patterns of heterochromatin in mitotic and polytene chromosomes of seven species belonging to 3 subgroups melanogaster sub-group: D. melanogaster and D. simulans; montium sub-group: D. kikkawai and D. jambulina; ananassae sub-group: D. ananassae, D. malerkotliana and D. bipectinata) of the melanogaster species group of Drosophila (Sophophora) has been made. Hoechst 33258 (H) fluorescence patterns of mitotic chromosomes reveal differences correlated to the taxonomic groupings of these species. The melanogaster sub-group species have H-bright regions on heterochromatin of all chromosomes; the montium subgroup species have H-bright regions mainly on the 4th and Y-chromosomes; in the ananassae sub-group, while D. ananassae chromosomes do not show any H-bright regions, D. malerkotliana and D. bipectinata have small H-bright segments only on their 4th chromosomes. The H-and quinacrine mustard (QM) fluorescence patterns of larval salivary gland polytene chromocentre in these species, however, do not show the same taxonomic correlation. While D. ananassae and D. kikkawai polytene nuclei lack any H-or QMbright region in the chromocentre, the remaining species have prominent H-and/or QM-bright region(s). In D. jambulina, the QM-bright regions are generally bigger than H-bright regions, while in D. malerkotliana and D. bipectinata the situation is reversed. Actinomycin D counterstaining prior to H-staining of polytene preparations of each species confirms that the H-bright region/s in the chromocentre are composed of A-T rich sequences. In vivo labelling of salivary gland polytene nuclei with 5-bromodeoxyuridine for 24 to 48 h and subsequent H-staining reveals that in all the species, the H-bright regions do not replicate in 3rd instar stage and presumably represent the non-replicating alpha heterochromatin. Significantly, in all the species (excepting D. kikkawai and D. ananassae), the size, location and the number of H-and/or QM-bright regions were seen to vary in different polytene nuclei in the same gland. It seems that the organization and the extent of under-replication of alpha heterochromatin varies in different polytene nuclei. Present studies also show that even closely related species differ in the content and organization of H-bright heterochromatin. The 81 F band at the base of 3 R in D. melanogaster, but not in D. simulans, appears to contain non-replicating H-bright sequences in addition to replicating chromatin.     

Adaptive associations between total body color dimorphism and climatic stress‐related traits in a stenothermal circumtropical Drosophila species

Abstract Low desiccation resistance of Drosophila ananassae reflects its rarity outside the humid tropics. However, the ability of this sensitive species to evolve under seasonally varying subtropical areas is largely unknown. D. ananassae flies are mostly lighter during the rainy season but darker and lighter flies occur in the autumn season in northern India. We tested the hypothesis whether seasonally varying alternative body color phenotypes of D. ananassae vary in their levels of environmental stress tolerances and mating behavior. Thus, we investigated D. ananassae flies collected during rainy and autumn seasons for changes in body melanization and their genetic basis, desiccation‐related traits, cold tolerance and mating propensity. On the basis of genetic crosses, we found total body color dimorphism consistent with a single gene model in both sexes of D. ananassae. A significant increase in the frequency of the dark morph was observed during the drier autumn season, and body color phenotypes showed significant deviations from Hardy‐Weinberg equilibrium, which suggests climatic selection plays a role. Resistance to desiccation as well as cold stress were two‐ to three‐fold higher in the dark body color strain as compared with the light strain. On the basis of no‐choice mating experiments, we observed significantly higher assortative matings between dark morphs under desiccation or cold stress, and between light morphs under hot or higher humidity conditions. To the best of our knowledge, this is the first report on the ecological significance of seasonally varying total body color dimorphism in a tropical species, D. ananassae.