Rich Bifurcation Structure of Prey–Predator Model Induced by the Allee Effect in the Growth of Generalist Predator

Prey–predator models are building blocks for many food-chain and food-web models in theoretical population biology. These models can be divided into two groups depending on the nature of predators, namely, specialist predator and generalist predator. Generalist predators can survive in the absence of prey but specialist predators go to extinction. Prey–predator models with specialist predator and Allee effect in prey growth have been investigated by several researchers and various types of interesting dynamics have been reported. In this paper, we consider a prey–predator model with generalist predator subject to Allee effect in predator’s growth rate. In general, a prey–predator system with saturating functional response can be destabilized due to the increase of the carrying capacity of prey which is known as paradox of enrichment. In our model with Allee effect in predator growth, we have shown that increase in carrying capacity of prey helps the populations to survive in a coexistence steady state. The considered model is capable of producing bistable dynamics for a reasonable range of parameter values. The complete dynamics of the system are quite rich and all possible local and global bifurcations are studied to understand the dynamics of the model. Analytical results are verified with numerical examples and successive bifurcations are identified with the help of bifurcation diagrams.

The life history and feeding ecology of velvet shell, Velutina velutina (Gastropoda: Velutinidae), a specialist predator of ascidians

Velvet shell, Velutina velutina (Müller, 1776), is a specialist predator of ascidians, like other members of the gastropod family Velutinidae. Globally, invasive ascidians have become problematic, ecologically and economically, yet ecological knowledge of velutinids remains limited. This study outlines the life history and feeding ecology of V. velutina in eastern Canada based on laboratory work complemented by field observations. The life history of V. velutina is closely linked with ascidians, which serve as prey and protection for their egg capsules. Egg capsules were embedded within tunics of Aplidium glabrum (Verrill, 1871) and Ascidia callosa Stimpson, 1852, with a preference for the latter. Seasonal behavioural shifts were consistent annually and corresponded with seawater temperature cycles. Feeding dominated during the coldest months (January–May), growth occurred as water temperature increased to the annual maximum (June and July), transitioning to mating during the warmest period (July–August), and egg capsule deposition dominated as water temperature declined (November–January). Larvae hatched between January and July after 2–4 months of development. Velutina velutina preyed on all ascidian species presented during this study, including golden star tunicate, Botryllus schlosseri (Pallas, 1766), and vase tunicate, Ciona intestinalis (Linnaeus, 1767), two non-indigenous species, although solitary species were preferred.

PREDATION ON Scinax fuscovarius (ANURA, HYLIDAE) BY Scolopendra sp. (CHILOPODA: SCHOLOPENDRIDAE) IN THE STATE OF TOCANTINS, CENTRAL BRAZIL

Some arthropods groups produce substantial mortality in some vertebrate populations and have complex ecological interspecific interactions with vertebrates. Amphibians are preyed by invertebrates at all life stages, however no invertebrate species is recognized as specialist predator of this group. This short communication reports the predation of anuran by a centipede.