<i>Drosophila ananassae</i>: A good model species for genetical, behavioural and evolutionary studies

333-345 Drosophila ananassae, a cosmopolitan and domestic species, was first described by Doleschall in 1858 from Indonesia. During 1930s, cytological and genetical investigations in D. ananassae were initiated in Japan and USA which showed that it is a genetically unique species. Since then a large number of studies have been carried out by researchers in Japan, USA, India, France and Germany in this genetically unique species. Present review briefly summarizes the work done on genetical, behavioural and evolutionary aspects in D. ananassae which demonstrates that it is a good model species for such studies. Further, it is also discussed how the work on D. ananassae has enriched our understanding of basic phenomena like evolution and behaviour compared to similar studies on other model Drosophilds  like D. melanogaster, D. pseudoobscura or D.subobsura. </smarttagtype

Mating latency, duration of copulation and fertility in four species of the <i style="mso-bidi-font-style:normal">Drosophila bipectinata</i> complex

175-180Significant interspecific variations in mean duration of copulation and fertility were observed in four species of the Drosophila bipectinata species complex. However, D. bipectinata showed positive correlation between duration of copulation and fertility. Similarly, D. malerkotliana showed negative correlation between mating latency and duration of copulation. Likewise, D. pseudoananassae<b style="mso-bidi-font-weight: normal"> showed positive correlation between mating latency and fertility. These results suggest that D. pseudoananassae has distant relatedness from the other three species with respect to mating latency, duration of copulation and fertility which supports the previous findings

Influence of age on mating propensity in two sibling species, <em>Drosophila</em> <em>ananassae</em> and <em>D. pallidosa</em>

7-13Mating propensity in Drosophila is affected by a number of factors including age of flies. Here, we studied the age factor in two sibling species of Drosophila. We tested the effect of age on mating propensity of two sibling species (Drosophila ananassae and D. pallidosa) using five wild type strains of D. ananassae and three wild type strains of D. pallidosa. To determine the effect of age on mating propensity, five age groups were selected: 4, 8, 12, 16 and 20 days of each strain of D. ananassae and D. pallidosa. Fifteen pairs of flies were introduced into the Elens-Wattiaux mating chamber for direct observation for 60 min and in each strain, five replicates were run. Data were analyzed by one-way, two-way ANOVA and student&rsquo;s t-test. Mating propensity of all the strains of both the sibling species vary significantly. All the strains of both the sibling species showed increase in the mating propensity with age (up to 12 days) and then it decreased as the age prolonged suggesting that 12 days aged flies are more eager to mate. Age wise variation was more pronounced than strain wise variation in D. ananassae. However, it was just opposite in the case of D. pallidosa. Mating propensity of D. ananassae was significantly higher as compared to D. pallidosa in each age group

Experimental evidence for nutrition regulated stress resistance in Drosophila ananassae.

The amount and quality of nutrients consumed by organisms have a strong impact on stress resistance, life-history traits and reproduction. The balance between energy acquisition and expenditure is crucial to the survival and reproductive success of animals. The ability of organisms to adjust their development, physiology or behavior in response to environmental conditions, called phenotypic plasticity, is a defining property of life. One of the most familiar and important examples of phenotypic plasticity is the response of stress tolerance and reproduction to changes in developmental nutrition. Larval nutrition may affect a range of different life-history traits as well as responses to environmental stress in adult.Here we investigate the effect of larval nutrition on desiccation, starvation, chill-coma recovery, heat resistance as well as egg to adult viability, egg production and ovariole number in Drosophila ananassae. We raised larvae on either protein rich diet or carbohydrate rich diet. We found that flies consuming protein rich diet have higher desiccation and heat shock resistance whereas flies developed on carbohydrate rich diet have higher starvation and cold resistance. Egg production was higher in females developed on protein rich diet and we also found trade-off between egg production and Egg to adult viability of the flies. Viability was higher in carbohydrate rich diet. However, sex specific viability was found in different nutritional regimes. Higher Egg production might be due to higher ovariole number in females of protein rich diet.Thus, Drosophila ananassae adapts different stress tolerance and life-history strategies according to the quality of the available diet, which are correlated with phenotypic adjustment at anatomical and physiological levels

Two – way ANOVA for egg to adult viability in either protein or carbohydrate-enriched medium.

<p>Two – way ANOVA for egg to adult viability in either protein or carbohydrate-enriched medium.</p

Ovariole number, egg production and egg to adult viability of flies developing on protein rich diet and carbohydrate rich diet. Bar represents Mean ±SE.

<p>Ovariole number, egg production and egg to adult viability of flies developing on protein rich diet and carbohydrate rich diet. Bar represents Mean ±SE.</p

Survival curves for starvation resistance in males (A) and females (B) derived from either protein (–) or carbohydrate (- - -) enriched medium.

<p>Survival curves for starvation resistance in males (A) and females (B) derived from either protein (–) or carbohydrate (- - -) enriched medium.</p