Factors Affecting Cannibalism Among Newly Hatched Wolf Spiders (Lycosidae, Pardosa Amentata)

Abstract

Cannibalism is a common phenomenon among young wolf spiders (Lycosidae). The purpose of this study was to investigate how various factors influence cannibalistic tendencies in hatchlings of Pardosa amentata (Clerk 1757). The basic experimental approach was to place pairs of unfed hatchlings of similar body mass in small containers without prey and to measure if and when cannibalism happened. From the data, we identified three different cannibalistic strategies. One large group of hatchlings never cannibalized and thus died from starvation. Another group cannibalized shortly before the time at which they were predicted to die from starvation. In these spiders, there was a strong positive relationship between average body mass of the contestants and their latency to cannibalize. A third group cannibalized quickly and the latency to cannibalize in these spiders was independent of body mass. We also tested if cannibalistic tendencies were higher among unrelated pairs than among pairs of siblings, but we did not find any support for this hypothesis. In another experiment we tested if maternal effects influenced cannibalism, i.e. if siblings from certain mothers were more cannibalistic than siblings from others. We did not find any evidence that maternal effects influenced whether or not cannibalism occurred. However, when cannibalism did occur, the latency to cannibalize varied significantly among siblings from different mothers beyond what would have been predicted solely from hatchling body mass.

Kin-selected siblicide and cannibalism in the European earwig

“…For instance, Pfennig et al (1993) observed direct siblicide and cannibalism in their study on polyphenism in tadpoles of the spadfoot toad (Scaphiopus bombifrons), and they found that carnivores consume significantly fewer siblings than nonsiblings. A majority of studies report indirect evidence for cannibalism by observing that individuals disappeared and remaining bodies or body parts (dragonfly larvae Aeshna juncea and Tramea carolina [Van Buskirk 1989; damselfly larvae Megaloprepus coerulatus [Fincke 1994]; wolf spiders Pardosa amentata [Hvam et al 2005]), not allowing the discrimination between nest-mate killing and cannibalism and the associated fitness consequences. With the simulation of the survival of victims and survivors in control individuals, that is, noninteracting ''pairs,'' we created the distribution of expected survival probabilities for victims and survivors under the null hypothesis.…”

“…Conspecific killing, siblicide, and cannibalism are common behaviors for invertebrates (e.g., Fincke 1994;Bilde and Lubin 2001;Hvam et al 2005) and these behaviors occur also in vertebrates (e.g., O'Connor 1978;Pfennig 1997). However, clear experimental separation for killing and siblicide and their fitness consequences (i.e., whether cannibalized individuals got killed or whether they died for another reason) is still scarce, probably partly due to the difficulty of observing the killing events per se.…”

“…A variety of experiments were carried out with different study organisms to gain insight into the evolution of siblicide or cannibalism (e.g., Van Buskirk 1989;Fincke 1994;Pfennig et al 1999;Hvam et al 2005;Schneider and Bilde 2008). As expected, it was generally found that siblicide reduced density and competition and that cannibalism increased the survival of the aggressor (Van Buskirk 1989;Fincke 1994).…”

“…As expected, it was generally found that siblicide reduced density and competition and that cannibalism increased the survival of the aggressor (Van Buskirk 1989;Fincke 1994). It has also been shown that body size or weight can influence the siblicidal and cannibalistic behavior (e.g., O'Connor 1978;Van Buskirk 1992;Fincke 1994;Hvam et al 2005). However, our quantitative understanding of fitness components due to siblicide and cannibalism in the evolution of sibling interactions is still limited.…”

Do cannibalism and kin recognition occur in just-emerged crab spiderlings?

“…Cannibalism, the ingestion of all or part of a conspecific (Pfennig 1997), occurs naturally in a wide range of animals (Pfennig 1997;Osawa 2002;Hvam et al 2005). However, its impact within populations typically has elicited only limited attention (Fox 1975;Polis 1981;Elgar & Crespi 1992), and it remains relatively poorly understood (Wilder & Rypstra 2010.…”