Fine‐scale selection by ovipositing females increases egg survival

Abstract

One of the most important defenses for the eggs of ovipositing female organisms is to avoid being laid in the same habitat as their predators. However, for most organisms, completely avoiding an offspring's predators is not possible. One mechanism that has been largely overlooked is for females to partition an oviposition site into microhabitats that differ in quality for offspring survival. We conducted a series of experiments to examine whether female newts avoid microhabitats utilized by their offspring's primary predator, caddisfly larvae. Female newts avoided laying eggs near predatory caddisflies and shifted egg laying upward in the water column when provided with a vertical dimension. Caddisflies were attracted to chemical stimuli from female newts and their eggs, yet primarily used benthic areas in experimental chambers. Finally, results from a field experiment indicate that the behavioral strategy employed by female newts increases offspring survival. This subset of non-genetic maternal effects, micro-oviposition avoidance, is likely an important yet underexplored mechanism by which females increase offspring survival.

Within‐patch oviposition site shifts by spider mites in response to prior predation risks decrease predator patch exploitation

“…Prey eggs and juveniles are generally vulnerable to predators and, be- Amano et al, 2008;Gall et al, 2012;Lucas & Brodeur, 1999). We demonstrated that precautionary micro-oviposition shifts (i.e., oviposition site shift within patches) of spider mites in predator-free patches, based on previously experienced predation risks, could decrease predator patch exploitation.…”

“…Prey eggs and juveniles are generally vulnerable to predators and, because loss of offspring reduces parents’ inclusive fitness (Hamilton, ), parental attention to avoiding offspring predation is particularly important. Females can reduce offspring predation by ovipositing in relatively protected microhabitats within patches (e.g., Amano et al., ; Gall et al., ; Lucas & Brodeur, ). We demonstrated that precautionary micro‐oviposition shifts (i.e., oviposition site shift within patches) of spider mites in predator‐free patches, based on previously experienced predation risks, could decrease predator patch exploitation.…”

“…In general, females select oviposition sites on two scales, between and within patches. While selecting patches without predators increases offspring survival (e.g., Chesson, 1984;Resetarits & Wilbur, 1989;Spieler & Linsenmair, 1997), micro-oviposition selection is advantageous when predation risk is ubiquitous in most patches (Gall et al, 2012), the ability of females to disperse between patches or detect adjacent patches is limited (Meng et al, 2012), and lethal and nonlethal costs of dispersal (Bonte et al, 2012) are high for females. In the case of T. kanzawai, predatory mites are not ubiquitously distributed, but spatially associated with spider mites on host plants (Nachappa, Margolies, Nechols & Campbell, 2011).…”

“…When predator-free patches are unavailable or movement between patches is costly for the ovipositing female, within-patch microhabitat use for oviposition (hereafter referred to as "micro-oviposition selection") against predators is favored (Gall, Brodie, & Brodie, 2012;Meng, Sabelis, & Janssen, 2012). Studies have reported predatorinduced micro-oviposition selection that reduces offspring predation in newts (Gall et al, 2012), predatory midges (Lucas & Brodeur, 1999), water striders (Amano, Hayashi, & Kasuya, 2008;Hirayama & Kasuya, 2009), and herbivorous mites (Lemos et al, 2010). With the exception of these works, induced micro-oviposition selection has been poorly studied, in part because its potential benefits can be overlooked or underestimated in typical laboratory conditions where predators do not have the opportunity to disperse from prey patches due to the experimental design.…”

Complex predator–prey interactions between the rusty crayfish (Orconectes rusticus) and invertebrate and vertebrate prey within their native range

“…Gall, unpublished data). Nevertheless, some common predator avoidance behaviors include changes in activity and distribution patterns (Richmond & Lasenby 2006;Ferrari et al 2010), and although neither isopods or salamander larvae modified their immediate behavior in response to crayfish stimuli, prey may also reduce predation risk by spatially avoiding the potential predator (e.g., Gall et al 2012). Again, however, neither isopods nor salamander larvae modified their position within the substrate in response to crayfish chemical cues.…”