A fecundity cost of (walking) mobility in an insect

Abstract

Evolutionary theory predicts trade-offs between fecundity and mobility, but there is substantial lack of empirical evidence if and how basic mobility relates to fitness costs. In a field experiment, we investigated fecundity costs of mobility in a non-migratory, wing-monomorphic grasshopper, Stenobothrus lineatus, and at the same time tested for possible effects of reproductive state (egg-load) on the mobility. For 10 days, body weight and activity radius of 60 females were recorded daily and oviposition events were inferred from abrupt weight losses. We found a strong and significant relationship between the individual mobility and the time between egg pods laid (interpod period). Individual egg-laying was reduced by a rate of 0.36 eggs per day with each meter increase in mean daily activity radius. The trade-off was not biased by the size of the females, that is, constitution did not positively influence both offspring number and mobility. Egg-load had no significant influence on the individual distances travelled. We could demonstrate that mobility – as induced and selected for by foraging, thermoregulation, predator escape, shelter seeking, and reproduction – can be directly paid off by fecundity. This direct consequence of mobility on individual fitness was detected for the first time in a walking insect.

Wing shape patterns among urban, suburban, and rural populations ofIschnura elegans(Odonata: Coenagrionidae)

“…However, after becoming sexually mature, females only return to breeding sites when they are receptive (Corbet, 1999) and undergo stronger selective pressure to forage (Anholt, 1992), whereas males tend to stay close to breeding sites in order to find a mate (Beirinckx, Van Gossum, Lajeunesse, & Forbes, 2006;Corbet, 1999), therefore females may need to be more dispersive than males (Beirinckx et al, 2006). Moreover, females can also show impaired locomotor performance once they become gravid (Carlson, McGinley, & Rowe, 2014;Olsson, Shine, & Bak-Olsson, 2000;Samietz & Köhler, 2012;Shine, 2003) and in flying organisms, pregnancy has shown to affect take-off negatively (Almbro & Kullberg, 2012;Lee, Witter, Cuthill, & Goldsmith, 1996;Veasey, Houston, & Metcalfe, 2001). In such case, the larger, longer, and narrower wing pattern found in females could be of aid for long-distance dispersal, since the angular velocity increases towards the wing tip in flapping wings, notably in petiolated wings where the velocity gradient from base to tip is more pronounced (Bomphrey et al, 2016;Dudley, 2000), thus providing more lift per wingbeat (Bomphrey et al, 2016).…”

Potential syndromes linking dispersal and reproduction in the hermaphrodite land snail Cornu aspersum

“…This trade-off has been largely analysed in wing dimorphic insects (Guerra, 2011), but also exists in species exhibiting continuous variation in mobility and reproduction (e.g. in a walking grasshopper; Samietz & K€ ohler, 2012). However, the actual relationship between fecundity and dispersal may not be so straightforward, depending on the considered taxa (Ronce & Clobert, 2012).…”

Mobility cost and degenerated diffusion in kinesis models

“…In general, it is hardly known if and how mobility transfers to fitness costs. The fecundity costs of mobility in some insects was measured in field experiment (in non-migratory, wing-monomorphic grasshopper, Stenobothrus lineatus) (Samietz and Köhler, 2012). For some other insects (the Glanville fritillary butterfly Melitaea cinxia) the fecundity cost of mobility was not found (Hanski et al, 2006).…”