Correlates of sexual dimorphism for dry weight and development time in five species of Drosophila

Abstract

Pre-adult development time, dry weight at eclosion, and daily fecundity over the first 10 days of adult life were measured in five species of Drosophila from the melanogaster and immigrans species groups. Overall, the three species of the melanogaster group (D. melanogaster, D. ananassae, D. malerkotliana) developed faster, were lighter at eclosion, and produced more eggs per unit weight at eclosion than the two species of the immigrans group (D. n. nasuta, D. sulfurigaster neonasuta). The degree of sexual dimorphism in dry weight was greater than that in development time, but did not vary significantly among species, and was not correlated with fecundity, contrary to expectations that sexual selection for increased fecundity drives sexual size dimorphism in Drosophila. The degree of dimorphism in development time was significantly correlated with dry weight and fecundity, with lighter species tending to be more dimorphic for development time as well as more fecund, both in absolute terms and in terms of fecundity per unit weight. The results suggest that our understanding of the evolutionary forces maintaining sexual size dimorphism in Drosophila will probably benefit from more detailed studies on the correlates of sexual dimorphism within and among Drosophila species, and on the shape of reaction norms for the degree of sexual dimorphism across different levels of ecologically relevant environmental variables.

Adaptation to larval crowding in Drosophila ananassae and Drosophila nasuta nasuta: increased larval competitive ability without increased larval feeding rate

“…In general, pre-adult development time in D. n. nasuta was higher than that in D. ananassae, as also noted earlier (Sharmila Bharathi et al 2004). Pre-adult development time was, in general, greater in males than in females, and greater at high rather than low larval density, as is usually the case in Drosophila (Figures 2,3, Table 2).…”

“…In D. n. nasuta, all pre-adult life-stages differed significantly from one another in duration, with a 23 h egg stage, followed by two larval instars of about 27 and 29 h, respectively, a longer third larval instar of about 63 h and a pupal stage lasting about 87 h (Figure 4B). The longer larval instar durations in D. n. nasuta are consistent with their larger adult size compared to D. ananassae (Sharmila Bharathi et al 2004). D. n. nasuta also showed a significant selection regime × life-stage duration interaction (Table 3), with a large (~12 h) reduction in third instar duration in the NCU populations (Figure 4B).…”

Adaptation to larval crowding inDrosophila ananassaeandDrosophila nasuta nasuta: increased larval competitive ability without increased larval feeding rate

“…In general, pre-adult development time in D. n. nasuta was higher than that in D. 421 ananassae, as also noted earlier (Sharmila Bharathi et al 2004). Pre-adult development 422 time was, in general, greater in males than in females, and greater at high rather than low 423 larval density, as is usually the case in Drosophila (Figures 2,3, Table 2).…”

Resource use by individual Drosophila suzukii reveals a flexible preference for oviposition into healthy fruits

“…We used generalised linear models (GLMs) to investigate the relation between the two fixed effects initial egg density (eggs per gram blueberry) and blueberry treatment (intact versus wounded fruits) and each response variable (survivorship, mean adult dry weight, median development time). As Drosophila is known to exhibit sexual size dimorphism 23 , sex was added as fixed effect in the analysis of adult dry weight. Development time as well as adult dry weight were modelled using a GLM with Gamma error structure and log link, whereas for survival data we specified a binomial GLM with a logit link function and corrected for under-dispersion.…”