Field experiments using small replicated enclosures focused on interactions between larval populations of Epitheca cynosura and Ladona deplanata (Odonata: Anisoptera) - two species that emerge in early spring. The presence of Epitheca reduced the total biomass of Ladona, but Ladona had no significant effect on Epitheca. These early-emerging species reduced the biomass of small instars of late-emerging Anisoptera which colonized enclosures during the experiments; and the late-emerging Anisoptera seem to have inhibited colonization by Zygoptera larvae. Results are consistent with the importance of predatory (cannibalism or mutual predation) interactions in this community.

No description available.

No / One of the most inimical ways to debase a people is to declare them cannibals - eaters of their own kind. The association between cannibalism and immorality, depravity, and base iniquity has contributed to the long-term interest in the behaviour. It has become a commonplace pejorative applied to exotic peoples, enemies, and strangers - sometimes and, more innocuously perhaps, to titillate fascination and, more sinisterly and more often, to dehumanise another group. Tuzin (1983, 62) characterises the Ilahita Arapesh's (of northeastern New Guinea) attitude towards the cannibalism of the downstream Sepik, "... as an amused, faintly condescending interest that is morally neutral in tone...'and that those who engage in such consumption are described as an 'another kind of man'. The apparent relativism of this statement, although lacking in obvious contempt or fear, provides the basis upon which difference could be accentuated to justify actions at another time or under different circumstances. The use of the term 'cannibalism' among both Europeans and non-Europeans (see Strathern 1982, Rumsey 1999) to make a people less than human - with real social and political consequences for those so-labeled - prompted Arens (1979) to deny that the behaviour had ever been practised. Others have argued that it did occur upon occasion in a number of circumstances and for a variety of reasons.

acase@tulane.edu

The Gram positive soil dwelling bacteria Bacillus subtilis produces spores when encountered with a low nutrient environment. However, B. subtilis can delay spore production by a mechanism known as cannibalism. Cannibalism is a process by which B. subtilis delays commitment to sporulation by killing a subpopulation of its cells. This process involves production of two toxins, SDP and SKF. SDP is a 42 amino acid peptide with a disulfide bond derived from the internal cleavage of its precursor protein pro-SdpC. pro-SdpC is part of the sdpABC operon. Production of extracellular SDP induces expression of the sdpRI operon. Encoded in this operon is the negative regulator SdpR and SdpI. SdpI is a dual function protein which acts both as a signal transduction protein and the immunity factor against SDP. The current model states that production of SDP is sensed via SdpI. SdpI will sequester SdpR to the membrane in response and allow for sdpRI expression. The aims of this dissertation are to establish the requirements for SDP production and its response via SdpI/SdpR during cannibalism. Studies in Chapter II were carried out to determine the factors required for production of the antimicrobial peptide SDP. Site directed mutagenesis of the leader signal peptide sequence in pro-SdpC demonstrated that proper signal peptide cleavage was required for SDP production. Additional site directed mutants of the cysteine residues in pro-SdpC revealed that these are not required for SDP toxic activity. These studies also included deletions within the sdpABC operon and revealed that the two proteins of unknown function, SdpA and SdpB are required for SDP production. Using mass spectrometry analysis, we found that SdpA and SdpB together are required to produce the active 42 amino acid peptide SDP. Taken together we concluded that SDP production was a multi step process which required proteins encoded within the operon and additional processing supplemented in the cell. In Chapter III we investigated the role of SdpI, specifically what residues were required for the signaling and immunity functions observed. Our initial screen, included site directed mutagenesis of highly conserved residues between the 4th and 5th transmembrane domains of SdpI. These resulted in over 20 SdpI mutants generated. From these, only two SdpI mutants had defects in either signal transduction or SDP immunity. Additional localized mutagenesis was used to isolate two other mutants in SdpI which only affected signal transduction or SDP immunity. SdpI signaling-immunity+ mutants presented a defect in SdpR membrane sequestration and sdpRIinduction. Our findings suggest these types of SdpI mutants may be important for the downstream effect of SdpR membrane sequestration. SdpI signaling+ immunity- mutants revealed defects in SDP protection. Some of the residues mutated were conserved in other SdpI homologs. Site directed mutagenesis of these conserved residues in the SdpI ortholog YfhL showed these are also required for SDP resistance. For the first time, we were able to identify mutations which affected only SDP immunity and gained further insight into how SdpI signaling-immunity+ mutants play a role during signal transduction. In Chapter IV we initiated studies to define what regions of the negative regulator SdpR are important for its function during cannibalism. We employed localized mutagenesis to identify SdpR mutants which decreased sdpRIexpression even in the presence of inducing signal. We isolated three such SdpR mutants, referred to as super repressors. We expect these SdpR super repressors are unable to be sequestered to the membrane in the presence of SDP.

Pre-copulatory sexual cannibalism (pre-SC), or predation of a potential mate before sperm transfer, provides an ideal model system for behavioral ecology's current focus on inter-sexual conflict. Studying the North American fishing spider (Dolomedes triton), I tested three female-benefit hypotheses for pre-SC: indirect benefits, direct benefits, and aggressive spillover. First, pre-SC may reflect a mating bias providing females with 'good-genes' benefits. By manipulating each female's options with regard to the most cited phenotypic advantage in male spiders, body size, I show that while females exhibit no bias in their attack tendency on males of different body sizes, large males mate significantly more often than small males. Second, pre-SC may be explained by direct benefits if females use it as an adaptive foraging/mating trade-off. My work provides mixed support for this idea: (i) females vary attacks according to the availability of mates, (ii) females do not vary attacks according to the availability of food, and (iii) females derive discrete fecundity benefits from consuming a male. Finally, I tested the aggressive-spillover hypothesis, which posits that pre-SC is a by-product of selection for high levels of aggression towards prey in traditional foraging contexts. Path analysis indicated intra-individual, positive correlations between aggression in foraging contexts and the mating context, thus supporting the hypothesis. I conclude by stressing that pre-SC in a given species may rarely be explained by one hypothesis, and that studies accounting for multiple benefits that fluctuate as behavioral-ecological contexts shift should give a more realistic glimpse of behavioral ecology and evolution.

Senior Honors thesis--Regis University, Denver, Colo., 2008. / Title from PDF title page (viewed on June 6, 2008). Includes bibliographical references.

Thesis (Honors)--College of William and Mary, 2009. / Includes bibliographical references (leaves 70-72). Also available via the World Wide Web.

Thesis (M.A.)--Victoria University of Wellington, 2008. / Includes bibliographical references.

Coexistence among ecologically similar species is often facilitated through temporal or spatial partitioning mechanisms that reduce or eliminate direct interaction. However, in many communities exhibiting guild structure, wherein potential competitors may also prey on one another, sympatric relationships persist despite species' similar life history strategies, spatial and temporal restrictions imposed by ephemeral habitats, and resource limitations that promote competition and predation. To identify the ecological roles of species-specific behavioral patterns within aquatic guilds, I quantified larval intraspecific agonistic behavior among two species of intraguild (IG) predators, Ambystoma opacum and A. tigrinum, and their shared intraguild prey, A. maculatum. All species exhibited similar ontogenetic patterns of aggression, characterized by peaks of aggression early in development and subsequent gradual decreases through metamorphosis. However, the intensity of aggression varied considerably among guild species through development, as did behavioral responses to varying levels of ambient water temperature, invertebrate prey density, and presence of predatory odonate naiads. The observed patterns suggest that guild species, despite morphological and physiological similarities, exhibit unique behavioral responses through ontogeny and in response to habitat variables, suggesting that temporally staggered breeding phenologies have contributed to behavioral divergence among these sympatric congeners. However, in situ observations of larval behavior, although largely in agreement with laboratory results on timing of increased aggression, indicated that IG predators exhibited pond-level species partitioning and do not necessarily co-occur despite being regarded as sympatric. These results, taken together with observed species-specific impacts of IG predators on IG prey, suggest that ecologically similar IG predators exert widely differing predatory pressure on shared prey, and that similarities among guild species may ultimately result in habitat partitioning across local scales.