The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Chadwick J Johnson - One of the best experts on this subject based on the ideXlab platform.
-
extreme developmental synchrony reduces sibling Cannibalism in the black widow spider latrodectus hesperus
Animal Behaviour, 2016Co-Authors: Chadwick J Johnson, Rebecca Halpin, Dale R StevensAbstract:Cannibalism, intraspecific predation, is a fascinating behaviour that can serve as a model system for researchers interested in learning more about conspecific conflicts ranging from siblicide to sexual Cannibalism. Cannibalism is most often studied in terms of the benefits it provides the predator, but the prevalence of such an ecologically significant behaviour is also shaped by the costs inherent in a cannibalistic attack. Perhaps most intuitively, the risk of injury when attacking a conspecific of similar or larger size has been considered, and led to the prediction that Cannibalism should be most common by larger individuals among asymmetrically sized pairs. This prediction is commonplace in the Cannibalism literature, and leads to the more novel hypothesis that siblicide then may be reduced to the extent that maternal investment yields developmental synchrony and size-matched siblings. Here we test these hypotheses in the western black widow spider, Latrodectus hesperus , by rearing some eggs at 4 °C warmer temperatures for 7 days, and thus experimentally creating size asymmetries between clutchmates. Our temperature manipulation was successful at speeding development (eggs reared at warmer temperatures attained their first moult 2.5 days sooner than their counterparts). This developmental asynchrony accelerated Cannibalism by more than 3 days relative to control groups in which eggs and spiderlings were all reared at either consistently colder or warmer temperatures. Lastly, the mass and size of an egg were poor predictors of Cannibalism in both treatments that included individuals reared at warm temperatures. In contrast, in our control group where both eggs were reared at cooler temperatures, we found that families typified by heavier and larger eggs were slower to show cannibalistic behaviour. We discuss the implications of these findings, paying particular attention to their relevance to the black widow's emerging role as an urban pest.
-
family affects sibling Cannibalism in the black widow spider latrodectus hesperus
Ethology, 2010Co-Authors: Chadwick J Johnson, Kathryn Kitchen, Maydianne C B AndradeAbstract:Adaptive foraging tactics are shaped by genes, the environment and gene–environment interactions. Because of relatively high levels of agonism toward conspecifics, spiders have been a popular focus for behavioral–ecological examinations of conspecific predation, or Cannibalism. Surprisingly, studies examining the underlying, proximate assumption that Cannibalism in spiders is a heritable trait shaped by interactions between genes and the environment are virtually non-existent. Here, we examine the influence of family on the expression of sibling Cannibalism in the post-hatching, group-living phase of an otherwise solitary, web-building spider, the North American black widow (Latrodectus hesperus). Our results showed significant levels of variation in cannibalistic propensity among 26 sibships, with some families cannibalizing full sibs within 2 d and other families waiting 3 wk before resorting to Cannibalism. A similar family-level effect was evident in measures of sibling cohabitation, voracity toward cricket prey, and development speed. Negative correlations between maternal egg sac investment and offspring Cannibalism suggest that this family effect may stem, at least in part, from a maternal effect, although we were not able to directly test the prediction that Cannibalism is most common from spiderlings in poor condition. Thus, we present novel data suggesting family effects seem to be responsible for Cannibalism in L. hesperus spiderlings; however, future work will be required to disentangle the relative importance of shared genes and shared maternal environment. We discuss several mechanisms that could explain the persistence of family-level variation in Cannibalism, a trait that seems likely to be subject to strong directional selection.
-
precopulatory sexual Cannibalism in fishing spiders dolomedes triton a role for behavioral syndromes
Behavioral Ecology and Sociobiology, 2005Co-Authors: Chadwick J Johnson, Andrew SihAbstract:Precopulatory sexual Cannibalism (predation of a potential mate prior to copulation) offers an extreme example of intersexual conflict, a current focus in behavioral ecology. The ‘aggressive-spillover’ hypothesis, posits that precopulatory sexual Cannibalism may be a nonadaptive by-product of a general syndrome of voracity (aggression towards prey) that is expressed in multiple behavioral contexts. In this view, selection favoring high levels of voracity throughout ontogeny spills over to cause sexual Cannibalism in adult females even when it is not necessarily beneficial. Using the North American fishing spider, Dolomedes triton, we present the first in depth test of this hypothesis. We found support for three aspects of the spillover hypothesis. First, voracity towards hetero-specific prey results in high feeding rates, large adult size, and increased fecundity. Second, juvenile and adult voracity are positively correlated (i.e., voracity is a consistent trait over ontogeny). Third, voracity towards hetero-specific prey is indeed positively correlated with precopulatory sexual Cannibalism. Assays of antipredator behavior further revealed positive correlations between boldness towards predators, voracity and precopulatory sexual Cannibalism. Overall, our results support the notion that precopulatory sexual Cannibalism in D. triton is part of a behavioral syndrome spanning at least three major contexts: foraging, predator avoidance, and mating.
Hiroyuki Iida - One of the best experts on this subject based on the ideXlab platform.
-
small within clutch variance in spiderling body size as a mechanism for avoiding sibling Cannibalism in the wolf spider pardosa pseudoannulata araneae lycosidae
Population Ecology, 2003Co-Authors: Hiroyuki IidaAbstract:This study investigated why sibling Cannibalism is so rare in the second instar of the wolf spider Pardosa pseudoannulata (Araneae: Lycosidae), despite the fact that the spider is cannibalistic and does not discriminate kin from non-kin. Laboratory experiments revealed that relative size difference between the cannibal and its victim affected the occurrence of nymphal Cannibalism, as in other spiders. The degree of the size difference, measured as the coefficient of variation (CV), was smaller within a brood than among broods, but was greater in smaller clutches that might have been produced by less well fed females. Statistical analysis confirmed that intraclutch Cannibalism would occur in less than about 1% of encounters among siblings that were randomly selected from the same clutch, because about 99% of intrabrood encounters fell within a 10% size difference, which is the marginal value above which frequent Cannibalism occurs. Thus, interclutch Cannibalism was expected to occur much more frequently than intraclutch Cannibalism. Considering the potential benefit of Cannibalism under food stress and high nymphal mortality, even with the sacrifice of their full sibs, the small intraclutch variance in spiderling body size may be understood as a tactic adopted by mother spiders to avoid sibling Cannibalism.
Yu Peng - One of the best experts on this subject based on the ideXlab platform.
-
factors influencing sexual Cannibalism and its benefit to fecundity and offspring survival in the wolf spider pardosa pseudoannulata araneae lycosidae
Behavioral Ecology and Sociobiology, 2013Co-Authors: Huaping Zhang, Zeliang Liu, Yu PengAbstract:Sexual Cannibalism is hypothesized to have evolved as a way to obtain a high-quality meal, as an extreme mate choice or as a consequence of female aggressive spillover. Here, we examined underlying factors likely to influence sexual Cannibalism in the wolf spider Pardosa pseudoannulata (Bosenberg & Strand, 1906) from China, including mating status, female egg-laid status, female hunger level, female adult age and mate size dimorphism. The results showed that about 10 % of P. pseudoannulata virgin females cannibalized the approaching males before mating and that 28 % of P. pseudoannulata virgin females immediately cannibalized the males after mating. No incidents of sexual Cannibalism during copulation were observed. Before mating, previously mated females and starved females tended to engage in significantly higher rates of attacks compared to virgin and well-fed females. Females that had laid egg sacs tended to engage in a significantly higher rate of attacks and sexual Cannibalism than virgin females before mating. Regardless of pre- or post-mating, there was a strong positive relationship between mate size dimorphism and the occurrence of sexual Cannibalism. We also tested the effects of sexual Cannibalism on the fecundity of cannibalistic females and the survival of their offspring. Our results indicated that sexual Cannibalism affected positively the offspring survival of cannibalistic females, but not fecundity. Our findings support the hypothesis that sexual Cannibalism has evolved as an adaptive component of female foraging strategy and that it benefits offspring survival as a result of paternal investment.
Allen W. Shostak - One of the best experts on this subject based on the ideXlab platform.
-
Sublethal Exposure to Diatomaceous Earth Increases Net Fecundity of Flour Beetles (Tribolium confusum) by Inhibiting Egg Cannibalism
2016Co-Authors: Allen W. ShostakAbstract:Population regulation results from an interplay of numerous intrinsic and external factors, and for many insects Cannibalism is such a factor. This study confirms a previously-reported observation that sublethal exposure to the fossilized remains of diatoms (i.e. diatomaceous earth) increases net fecundity (eggs produced minus eggs destroyed/day) of flour beetles, Tribolium confusum. The aim was to experimentally test two non-mutually-exclusive ecological mechanisms potentially responsible for the increased net fecundity: higher egg production and lower egg Cannibalism. Adult T. confusum were maintained at low or high density in medium containing sublethal (0–4%) diatomaceous earth. Net fecundity increased up to 2.16 control values during diatomaceous earth exposure, and returned to control levels following removal from diatomaceous earth. Cannibalism assays on adults showed that diatomaceous earth reduced the number of eggs produced to 0.76control values at low density and to 0.86controls at high density, and also reduced egg Cannibalism rates of adults to as little as 0.46control values, but at high density only. Diatomaceous earth also reduced Cannibalism by larvae on eggs to 0.36control values. So, while the presence of diatomaceous earth reduced egg production, net fecundity increased as a result of strong suppression of the normal egg Cannibalism by adults and larvae that occurs at high beetle density. Undisturbed cultures containing sublethal diatomaceous earth concentrations reached higher population densities than diatomaceous earth-free controls. Cohort studies on survival from egg to adult indicated that this population increase wa
-
Sublethal exposure to diatomaceous earth increases net fecundity of flour beetles (Tribolium confusum) by inhibiting egg Cannibalism.
PLoS ONE, 2014Co-Authors: Allen W. ShostakAbstract:Population regulation results from an interplay of numerous intrinsic and external factors, and for many insects Cannibalism is such a factor. This study confirms a previously-reported observation that sublethal exposure to the fossilized remains of diatoms (i.e. diatomaceous earth) increases net fecundity (eggs produced minus eggs destroyed/day) of flour beetles, Tribolium confusum. The aim was to experimentally test two non-mutually-exclusive ecological mechanisms potentially responsible for the increased net fecundity: higher egg production and lower egg Cannibalism. Adult T. confusum were maintained at low or high density in medium containing sublethal (0–4%) diatomaceous earth. Net fecundity increased up to 2.1× control values during diatomaceous earth exposure, and returned to control levels following removal from diatomaceous earth. Cannibalism assays on adults showed that diatomaceous earth reduced the number of eggs produced to 0.7× control values at low density and to 0.8× controls at high density, and also reduced egg Cannibalism rates of adults to as little as 0.4× control values, but at high density only. Diatomaceous earth also reduced Cannibalism by larvae on eggs to 0.3× control values. So, while the presence of diatomaceous earth reduced egg production, net fecundity increased as a result of strong suppression of the normal egg Cannibalism by adults and larvae that occurs at high beetle density. Undisturbed cultures containing sublethal diatomaceous earth concentrations reached higher population densities than diatomaceous earth-free controls. Cohort studies on survival from egg to adult indicated that this population increase was due largely to decreased egg Cannibalism by adult females. This is the first report of inhibition of egg Cannibalism by diatomaceous earth on larval or adult insects. The ability of diatomaceous earth to alter Cannibalism behavior without causing mortality makes it an ideal investigative tool for Cannibalism studies.
Dale R Stevens - One of the best experts on this subject based on the ideXlab platform.
-
extreme developmental synchrony reduces sibling Cannibalism in the black widow spider latrodectus hesperus
Animal Behaviour, 2016Co-Authors: Chadwick J Johnson, Rebecca Halpin, Dale R StevensAbstract:Cannibalism, intraspecific predation, is a fascinating behaviour that can serve as a model system for researchers interested in learning more about conspecific conflicts ranging from siblicide to sexual Cannibalism. Cannibalism is most often studied in terms of the benefits it provides the predator, but the prevalence of such an ecologically significant behaviour is also shaped by the costs inherent in a cannibalistic attack. Perhaps most intuitively, the risk of injury when attacking a conspecific of similar or larger size has been considered, and led to the prediction that Cannibalism should be most common by larger individuals among asymmetrically sized pairs. This prediction is commonplace in the Cannibalism literature, and leads to the more novel hypothesis that siblicide then may be reduced to the extent that maternal investment yields developmental synchrony and size-matched siblings. Here we test these hypotheses in the western black widow spider, Latrodectus hesperus , by rearing some eggs at 4 °C warmer temperatures for 7 days, and thus experimentally creating size asymmetries between clutchmates. Our temperature manipulation was successful at speeding development (eggs reared at warmer temperatures attained their first moult 2.5 days sooner than their counterparts). This developmental asynchrony accelerated Cannibalism by more than 3 days relative to control groups in which eggs and spiderlings were all reared at either consistently colder or warmer temperatures. Lastly, the mass and size of an egg were poor predictors of Cannibalism in both treatments that included individuals reared at warm temperatures. In contrast, in our control group where both eggs were reared at cooler temperatures, we found that families typified by heavier and larger eggs were slower to show cannibalistic behaviour. We discuss the implications of these findings, paying particular attention to their relevance to the black widow's emerging role as an urban pest.
