That predators attack and prey defend is an oversimplified view. When size changes during development, large prey may be invulnerable to predators, and small juvenile predators vulnerable to attack by prey. This in turn may trigger a defensive response in adult predators to protect their offspring. Indeed, when sizes overlap, one may wonder "who is the predator and who is the prey"! Experiments...

Invasive species threaten biodiversity globally, and invasive mammalian predators are particularly damaging, having contributed to considerable species decline and extinction. We provide a global metaanalysis of these impacts and reveal their full extent. Invasive predators are implicated in 87 bird, 45 mammal, and 10 reptile species extinctions-58% of these groups' contemporary extinctions wor...

background : suicide is a global public health problem. deliberate self-poisoning (dsp) is one of the most common methods of suicide in many countries. this study was designed to identify the trends and characteristics of dsp in gorgan. methods: the study was carried out retrospectively in 5 azar hospital. it included 549 patients who were hospitalized in the hospital due to dsp from march 2008...

A recent review of published studies revealed that predators generally have lower population densities than non-predators in a variety of communities. We report here similar results for a highly replicated study of macroinvertebrates that colonized very uniform detrital microcosms in an old field. This pattern persisted even though predators usually were smaller than non-predators, as determine...

Behavioral ecology and population ecology are two separate branches of ecology; studies linking the effect of individual behavior and population dynamics are rare. This paper connects a stochastic optimal foraging model of insect predators with an age structured population model of its prey. I modeled syrphid larvae feeding on cereal aphids, an interaction critical to cereal crops in Germany. T...

Calls of avian predators potentially predict danger for murine rodents. Indeed, exposure of field-experienced rodents to owl calls induces defensive behavior suggesting that recognition of vocalizations of avian predators is innate. To address this hypothesis, we investigated whether laboratory-reared and predator-naive rodents (mice, gerbils, rats) express defensive behavior in response to cal...

Although biologists routinely label animals as predators and prey, the ecological role of individuals is often far from clear. There are many examples of role reversals in predators and prey, where adult prey attack vulnerable young predators. This implies that juvenile prey that escape from predation and become adult can kill juvenile predators. We show that such an exposure of juvenile prey t...

Coevolution may be defined as an evolutionary change in a trait of one species in response to a change in a trait of a second species, followed by an evolutionary response by the second species to the changes in the first. Yet, more complex evolutionary relationships are known to occur, such as Batesian mimicry, where three or more separate species interact along their evolutionary history. Do ...

hyrcania (gorgan) has long attracted men of power due to its strategic and economic location. according to historical evidence, the iranian governments before the sassanid dynasty, attempted to dominate the region in order to consolidate their power. the sassanid dynasty, following the same policy of the former dynasties, not only established an important military base there but also constructe...