Body condition but not dietary restriction prolongs lifespan in a semelparous capital breeder

Abstract

Effects of diet on longevity are complex because acquired resources are shared among growth, reproduction and somatic maintenance. We simplify these axes by examining how dietary restriction and competitive contexts affect longevity using semelparous males of the Australian redback spider (Latrodectus hasselti). Plastic development of L. hasselti males results in trade-offs of body condition against faster development if females are present, facilitating scramble competition. In the absence of females, males develop slowly as high body condition adults, and are better equipped for mate searching. Here we focus on effects of diet and competitive context on body condition and longevity. Although male survival depended on body condition and exercise, contrary to studies in a wide range of taxa, dietary restriction did not increase longevity. However, there was an interactive effect of diet and competitive context on lifespan, because high-diet males reared in the absence of females lived longer than males reared in the presence of females. Thus males near females pay a survival cost of developing rapidly. This shows that life-history trade-offs affected by competitive context can impose longevity costs independent of the direct energy expenditure of searching, courtship, competition or reproduction.

Longevity cost of remaining unmated under dietary restriction

“…These data support the hypothesis that DR triggers adaptive mechanisms that increase longevity if reproduction can be delayed (Partridge, Gems & Withers 2005). These results are in contrast to a recent study of male redback spiders, in which adult condition and energy expenditure were the strongest predictors of longevity, with no direct effect of DR (Kasumovic, Brooks & Andrade 2009). This sex difference is consistent with life history hypotheses that posit effects of DR depend on how DR shapes the resource allocation trade‐offs inherent to reproduction.…”

“…Previous research has demonstrated that short‐lived male redback spiders survive approximately 20 days after becoming sexually mature (Andrade 2003) and do not increase their longevity under DR (Kasumovic, Brooks & Andrade 2009). It was suggested that this occurs because these males mate only once in their lifetime and die shortly afterwards (Andrade 1996, 2003), so DR should not be associated with reallocation of resources to somatic maintenance (Kasumovic, Brooks & Andrade 2009). This is consistent with the hypothesis that longevity effects of DR depend on allocation priorities shaped by the pattern and frequency of reproduction by adults.…”

Persistence and survival of the spider Nephila plumipes in cities: do increased prey resources drive the success of an urban exploiter?

“…On the other hand, increased resources have improved the success of both ants (Penick et al 2015) and granivorous birds (Kark et al 2007) in urban areas. In laboratory studies, feeding spiders more food either decreases longevity (Austad 1989;Spencer 1990) or has no effect (Kasumovic et al 2009). However, in the field prey density can increase population density, growth and development of select spider species Miyashita 1986;Wise 1995) but does not always increase spider species diversity (Greenstone 1984).…”

Dietary restriction in rats and mice: A meta-analysis and review of the evidence for genotype-dependent effects on lifespan

“…Nevertheless, contrary evidence has been reported. For example, DR protocols have failed to increase lifespan in D. melanogaster (Le Bourg and Minois, 1996; Le Bourg and Minois, 2005; Libert et al, 2007; Lee et al, 2008), the nematode C. remanei (Sutphin and Kaeberlein, 2008), medflies (Carey et al, 2002), rotifers (Kirk, 2001; Weithoff, 2007), butterflies (Beck, 2007; Molleman et al, 2009), the spider L. hasselti (Kasumovic et al, 2009), and houseflies (Cooper et al, 2004). Likewise, despite repeated demonstrations that DR can increase the lifespan of laboratory rodents (Weindruch and Walford, 1988; Turturro et al, 1999), recent studies appear to have identified strains that fail to exhibit increased lifespan in response to DR (Harper et al, 2006a; Liao et al, 2010a; Rikke et al, 2010).…”