Opposite Latitudinal Clines for First Mating and Second Mating (Remating) in Males of Drosophila melanogaster

Abstract

Although female remating has been studied extensively in insects, few studies have been carried out for male remating (second mating). In this study, we analyzed Drosophila melanogaster males for their remating potential, using iso-female line culture initiated with wild flies collected from eight Indian geographic localities. We examined the association of latitude and percent melanization with first and second male mating (including mating-related traits). Our results indicated that second male mating has a negative latitudinal cline opposite to that of first mating. Body melanization is negatively correlated with second mating by male and positively with first mating (measured in terms of percent mated pairs). Mating latency during first (ML1) and second (ML2) male mating has a negative latitudinal cline, but slope values differ significantly as ML2 is great at higher latitudes as compared to ML1. The difference between ML1 and ML2 is non-significant at lower latitudes. However, copulation period of second mating (CP2) has a negative latitudinal cline, whereas copulation period of first mating (CP1) has positive latitudinal cline. Next, the latency and copulation period differ significantly between first and second male mating treatments in within-population analyses as well as in melanic strains. Furthermore, male remating ability (number of maximum successful remating attempts continuously by a male in 12 h) also follows negative latitudinal cline. The lower latitudinal lighter males have more remating ability as compared to darker males from higher latitudes.

Temperature fluctuations during development reduce male fitness and may limit adaptive potential in tropical rainforest Drosophila

“…Such a consistent reduction in adult size is significant because male body size correlates strongly with mating success and lifetime reproductive success in Drosophila (Partridge & Farquhar, 1983). Mating success itself is also significantly reduced by high thermal stress (> 36°C) on adult males (Onder, 2009), and latitudinal clines in male mating-related traits in D. melanogaster suggest that abiotic conditions drive selection on remating (Chahal et al, 2013). What is not known, however, is as follows: (i) whether similar effects on male reproductive success are induced by temperature variation that is routinely experienced at the limits of an ecological distribution and (ii) whether exposure to such conditions during development affects the genetic variance and therefore adaptive potential of these fitness-related traits.…”

Low but genetically variable male remating ability in a tropicalDrosophiladespite substantial fitness benefits

“…Variation in abiotic conditions also affects insect mating duration (Horton et al , 2002), sperm allocation and remating rate (Katsuki and Miyatake, 2009) within genotypes. Latitudinal variation in male remating traits within two cosmopolitan Drosophila species has also been observed (Chahal et al , 2013; Singh and Singh, 2000). Bouletreaumerle et al (1982) found that female fecundity was lower in tropical versus temperate populations of D. melanogaster , suggesting that males of tropical species may also invest less in sperm or seminal components associated with the environments they inhabit.…”

“…For example, low resource availability may reduce male mating rates (Blay and Yuval, 1997) and their ability to produce sperm (Gage and Cook, 1994). Latitudinal clines in male mating traits indicate that environmental variation can determine such allocation patterns (Chahal et al , 2013).…”