Do mothers producing large offspring have to sacrifice fecundity?

Abstract

We artificially selected on egg size in a butterfly to study the consequences for fecundity, reproductive effort and offspring fitness. Correlated responses in either pupal mass, larval or pupal development time were virtually absent. Offspring size was positively related to fitness, but only partly traded off against fecundity. Rather, total reproductive effort (measured as fresh mass), egg water content and the decline of egg size with female age increased in the large‐egg selected lines compared to either small‐egg or control lines. Accounting for these effects showed that reproductive investment (in dry mass) was in fact similar across lines. Such mechanisms may enable increased investment in (early) offspring without a reduction in their number, revealing a much more complex picture than a simple trade‐off between offspring size and number. Substantial variation among replicates suggests that there are different underlying mechanisms for change, rather than any single, unitary pathway.

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

“…During selection, we also established lines selected purely on egg size. However, as could be expected from weak correlations between egg and body size (Fischer et al, 2002), there were no substantial differences between selection on egg size or residual egg size (see Fischer et al, 2006 Fischer et al, 2006). All selected lines had been established at 271C, and showed significant realized heritabilities for all traits targeted by selection and in all directions of selection.…”

“…10 eggs per female was measured for 100-160 females per line in each generation, from which 30 were selected as parents. As the eggs of B. anynana are nearly perfect spheres, egg size was measured as cross-sectional area (mm 2 ) using a digital camera (Leica DC200) connected to a binocular microscope (for details see Fischer et al, 2006). During selection, we also established lines selected purely on egg size.…”

“…Stearns, 1992;Fox and Czesak, 2000;Roff, 2002). Egg size in insects, for instance, can considerably affect the fitness of the progeny resulting from these eggs; larger offspring were frequently found to mature earlier, to have improved ability to avoid or withstand predation or competition, or to survive better in stressful environments compared with the small offspring (Azevedo et al, 1997;Fox and Czesak, 2000;Roff, 2002;Czesak and Fox, 2003;Fischer et al, 2003Fischer et al, , 2006. The considerable and wide-ranging ecological importance of a large body size is clearly demonstrated by its positive effect on various fitnessrelated traits (e.g.…”

Life history evolution and cellular mechanisms associated with increased size in high‐altitude Drosophila

“…Across many insects, larger eggs tend to produce larger adults, while egg size and egg number are inversely correlated (Parsons 1962; Harvey 1983, 1985; Berrigan 1991; but see Fischer et al. 2005; Hassall et al. 2006), potentially reflecting variation along the continuum between r and K reproductive strategies in terms of offspring number versus offspring size.…”

Adult longevity and its relationship with conservation status in European butterflies

“…Adult life span also afects realised fecundity, i.e. the number of eggs laid, which in turn can have a critical impact on population viability (Fischer et al 2006;Pijpe 2007;Haeler et al 2014). Low quantities Bilnicki (2015) Whenever more than one record was available for a species, we present the median with the range (min-max) in parentheses.…”