Venom and Social Behavior: The Potential of Using Spiders to Evaluate the Evolution of Sociality under High Risk

Risks of sociality, including competition and conspecific aggression, are particularly pronounced in venomous invertebrates such as arachnids. Spiders show a wide range of sociality, with differing levels of cannibalism and other types of social aggression. To have the greatest chance of surviving interactions with conspecifics, spiders must learn to assess and respond to risk. One of the major ways risk assessment is studied in spiders is via venom metering, in which spiders choose how much venom to use based on prey and predator characteristics. While venom metering in response to prey acquisition and predator defense is well-studied, less is known about its use in conspecific interactions. Here we argue that due to the wide range of both sociality and venom found in spiders, they are poised to be an excellent system for testing questions regarding whether and how venom use relates to the evolution of social behavior and, in return, whether social behavior influences venom use and evolution. We focus primarily on the widow spiders, Latrodectus, as a strong model for testing these hypotheses. Given that successful responses to risk are vital for maintaining sociality, comparative analysis of spider taxa in which venom metering and sociality vary can provide valuable insights into the evolution and maintenance of social behavior under risk.

Numerical Study of One Prey-Two Predator Model Considering Food Addition and Anti-Predator Defense

This article examines the interaction between prey populations, juvenile predators, and adult predators. A mathematical model that considers adding food and anti-predators was developed. The equilibria of the existing system are that the system has four equilibria points with conditions suitable for the locale. Numerical simulations were carried out to describe the dynamics of the system solution. Based on numerical simulations, the varying of parameter causes changes in the extinction of prey or survival of prey populations, juvenile predators, and adult predators. Addfood parameters (A) encourae Hopf Bifurcation and Saddle-node bifurcation Numerical continuity results show that Hopf bifurcation occurs when the parameter value A = 1.00162435 and when the parameter value A = 2.435303 Saddle-node bifurcation occurs.

Predator defense is shaped by risk, brood value and social group benefits in a cooperative breeder

Predation is a major cause of mortality and nest failure in birds. Cooperative predator defense can enhance nest success and adult survival but, because it is inherently risky, dynamic risk assessment theory predicts that individuals modify defense behavior according to the risk posed by the predator. Parental investment theory, on the other hand, predicts that reproductive payoffs (brood value) determine investment in nest defense. We propose that, in cooperative breeders, fitness benefits deriving from the survival of other group members may additionally influence defense behavior (social group benefits theory). We tested predictions of these theories in the cooperatively breeding purple-crowned fairy-wren, Malurus coronatus, where brood value is higher for breeders, but social group benefits more important for helpers. We recorded experimentally induced individual defense behaviors in response to predator models presented near nests, representing differing levels of threat to nests and adults. As predicted, 1) individuals engaged in less risky defenses when encountering a more dangerous predator (dynamic risk assessment theory); 2) individuals defended older broods more often, and breeders defended more than helpers (parental investment theory); and 3) helpers were more likely to respond to a predator of adults (social group benefits theory). Our findings highlight that predator defense in cooperative breeders is complex, shaped by the combination of immediate risk and multiple benefits.

The Role of Bacterial Natural Products in Predator Defense

Bacterially produced natural products, i.e., low molecular weight metabolites, or derivatives thereof, constitute most of the commercially available antibiotics as well as a large proportion of anticancer drugs. While indispensable as therapeutically active compounds, the ecological roles of many of these bacterial natural products remain poorly understood. Here, we discuss these metabolites in light of ­microbial predator defense: soil bacteria are constantly threatened by a variety of predators and the secretion of low molecular weight toxins enables the producing bacteria to kill or deter the predator. Conversely, a deeper understanding of these microbial predator–prey interactions can lead to the discovery of novel compounds, which in turn can be of therapeutic use.