Search results for "Predation"
showing 10 items of 589 documents
Attacks of songbirds in mixed‐species flocks by Eurasian Sparrowhawks: strategies of predators and potential prey
2020
The red tooth hypothesis: A computational model of predator-prey relations, protean escape behavior and sexual reproduction
2009
This paper presents an extension of the Red Queen Hypothesis (hereafter, RQH) that we call the Red Tooth Hypothesis (RTH). This hypothesis suggests that predator-prey relations may play a role in the maintenance of sexual reproduction in many higher animals. RTH is based on an interaction between learning on the part of predators and evolution on the part of prey. We present a simple predator-prey computer simulation that illustrates the effects of this interaction. This simulation suggests that the optimal escape strategy from the prey's standpoint would be to have a small number of highly reflexive, largely innate (and, therefore, very fast) escape patterns, but that would also be unlearn…
Differences in conspicuousness between alternative color morphs in a polychromatic lizard
2015
In polychromatic species, differences in conspicuousness among alternative color morphs may affect the costs and benefits relating to signal detectability by primary receivers and unintended observers. Using visual modeling, we studied the conspicuousness of the body coloration in a ventrally polychromatic population of common wall lizards (Podarcis muralis). This species shows a complex color pattern that combines brown dorsal coloration, long-wavelength–biased ventral coloration, and ventrolateral ultraviolet (UV)-blue patches that are used to signal male quality. Considering simultaneously the visual system of P. muralis and lizard predators, we quantified the chromatic and achromatic (i…
Chlorinated hydrocarbons and total mercury in the prey of the white-tailed eagle (Haliaeetus albicilla L.) in the quarken straits of the gulf of both…
1976
Samples of the white-tailed eagle population and its prey were collected from the Quarken straits area of the Gulf of Bothnia, Finland, and were analyzed for DDT, DDD, PCBs, aldrin, lindane, and mercury. Mercury, PCB, and DDE were detected in all animals studied. It was concluded that one of the most important reasons for the poor breeding results of the white-tained eagle (especially hatchability) are the combined effects of the studied pollutants originating for the most part from the fish-eating species in its prey (mergansers and great crested grebes). (JTE)
Variation in predator species abundance can cause variable selection pressure on warning signaling prey
2012
Predation pressure is expected to drive visual warning signals to evolve toward conspicuousness. However, coloration of defended species varies tremendously and can at certain instances be considered as more camouflaged rather than conspicuous. Recent theoretical studies suggest that the variation in signal conspicuousness can be caused by variation (within or between species) in predators' willingness to attack defended prey or by the broadness of the predators' signal generalization. If some of the predator species are capable of coping with the secondary defenses of their prey, selection can favor reduced prey signal conspicuousness via reduced detectability or recognition. In this study…
The effect of predator appetite, prey warning coloration and luminance on predator foraging decisions
2010
AbstractAposematic prey advertise their defence to visually hunting predators using conspicuous warning colouration. Established theory predicts that aposematic signals should evolve towards increased conspicuousness and similarity to enhance predator education. Contrary to theoretical expectations, there is often considerable within- and between-species variation in aposematic signals of animals sharing the same ecological niche, phylogeny and predators. This may be explained by varying responses of predators that weaken the selection pressure for a consistent signal. By presenting painted mealworm larvae as prey to great tits as predators we tested if different aposematic colour patterns …
Pool choice in a vertical landscape: tadpole rearing site flexibility in phytotelm-breeding frogs
2021
AbstractMany species of Neotropical frogs have evolved to deposit their tadpoles in small water bodies inside plant structures called phytotelmata. These pools are small enough to exclude large predators but have limited nutrients and high desiccation risk. Here, we explore phytotelm use by three common Neotropical species: Osteocephalus oophagus, an arboreal frog that periodically feeds eggs to its tadpoles; Dendrobates tinctorius, a tadpole-transporting poison frog with cannibalistic tadpoles; and Allobates femoralis, a terrestrial tadpole-transporting poison frog with omnivorous tadpoles. We found that D. tinctorius occupies pools across the chemical and vertical gradient, whereas A. fem…
Metazoan parasite communities and diet of the velvet belly lantern shark Etmopterus spinax (Squaliformes: Etmopteridae): a comparison of two deep-sea…
2014
By combining an examination of stomach contents yielding a snapshot of the most recent trophic niche and the structure of parasite communities reflecting a long-term feeding niche, this study aimed at gaining more comprehensive information on the role of the small-sized deep-water velvet belly lantern shark Etmopterus spinax in the local food webs of the Galicia Bank and the canyon and valley system of the Aviles Canyon, which have been both proposed for inclusion in the Natura 2000 network of protected areas. As far as is known, this study provides the first comparative parasite infracommunity data for a deep-sea shark species. Component parasite communities in E. spinax were relatively ri…
Effects of isolation, area and predators on invasion: A field experiment with artificial islands
2007
Abstract The three most important ecological factors affecting the success of island invasions are the area of the island, isolation of the island and occurrence of predators on the island. Traditionally, invasion success has been studied on natural islands, which partly explains the rarity of controlled and replicated experiments. Here we report results from a field experiment investigating the influence of the above three factors in artificial islands. As an experimental system, we used predatory mites and a nematode community occurring naturally in boreal coniferous forests. We found that all three factors had an effect on invasion success, but surprisingly, that there were no interactio…