Correlated Responses to Selection for Faster Development and Early Reproduction in Drosophila: The Evolution of Larval Traits

Abstract

Studies on selection for faster development in Drosophila have typically focused on the trade-offs among development time, adult weight, and adult life span. Relatively less attention has been paid to the evolution of preadult life stages and behaviors in response to such selection. We have earlier reported that four laboratory populations of D. melanogaster selected for faster development and early reproduction, relative to control populations, showed considerably reduced preadult development time and survivorship, dry weight at eclosion, and larval growth rates. Here we study the larval phase of these populations in greater detail. We show here that the reduction in development time after about 50 generations of selection is due to reduced duration of the first and third larval instars and the pupal stage, whereas the duration of the second larval instar has not changed. About 90% of the preadult mortality in the selected populations is due to larval mortality. The third instar larvae, pupae, and freshly eclosed adults of the selected populations weigh significantly less than controls, and this difference appears during the third larval instar. Thereafter, percentage weight loss during the pupal stage does not differ between selected and control populations. The minimum amount of time a larva must feed to subsequently complete development is lower in the selected populations, which also exhibit a syndrome of reduced energy expenditure through reduction in larval feeding rate, larval digging and foraging activity, and pupation height. Comparison of these results with those observed earlier in populations selected for adaptation to larval crowding and faster development under a different protocol from ours reveal differences in the evolved traits that suggest that the responses to selection for faster development are greatly affected by the larval density at which selection acts and on details of the selection pressures acting on the timing of reproduction.

Realized correlated responses to artificial selection on pre-adult life-history traits in a butterfly

“…In particular, we will address the following issues: (1) Is a short development time negatively related to a large body size as is regularly assumed in life-history theory (e.g. Stearns and Koella, 1986;Partridge et al, 1999;Prasad et al, 2001;Roff, 2002; but see Gotthard, 2004)? ; (2) Does large egg size correlate with large body size, as is commonly assumed owing to positive genetic correlations among these traits (e.g.…”

Risk and the Evolution of Cell-Cycle Durations of Embryos

“…In experimental selection for larval and pupal development times of Drosophila melanogaster, there was proportionately more change in the duration of the larval stage (with feeding and growth) than in the duration of embryonic or pupal stages (Chippendale et al 1994(Chippendale et al , 1997Prasad et al 2001). We wished to isolate evolution of development rate from the trade-offs for duration of life-history stages that arise from foraging, assimilation of food, or habitat selection.…”

Evolutionary responses to crude oil from the Deepwater Horizon oil spill by the copepod Eurytemora affinis

“…This pattern is similar to the case for selection on low salinity tolerance in E. affinis (Lee et al., 2003, 2007), where selection acts predominantly on the life history stage prior to metamorphosis. Selection acting more intensely during the early life‐history stages is commonly found in many different animal species (Garrido et al., 2015; Plough, Shin, & Hedgecock, 2016; Prasad, Shakarad, Anitha, Rajamani, & Joshi, 2001). …”