نتایج جستجو برای: predation rate
تعداد نتایج: 971157 فیلتر نتایج به سال:
Recent theoretical and empirical work argues that growth rate can evolve and be optimized, rather than always being maximized. Chronically low resource availability is predicted to favour the evolution of slow growth, whereas attaining a size-refuge from mortality risk is predicted to favour the evolution of rapid growth. Guppies (Poecilia reticulata) evolve differences in behaviour, morphology...
Avian life history theory has long assumed that nest predation plays a minor role in shaping reproductive strategies. Yet, this assumption remains conspicuously untested by broad experiments that alter environmental risk of nest predation, despite the fact that nest predation is a major source of reproductive failure. Here, we examined whether parents can assess experimentally reduced nest pred...
In the Mediterranean, fishing bans generally allow the recovery of populations of sea urchin predators, such as the seabreams Diplodus sargus and D. vulgaris, promoting the transformation of overgrazed communities into ones dominated by erect macroalgae. However, in the marine reserve on Ustica Island (SW Italy) the opposite trend has occurred in the upper infralittoral community, and urchin ba...
Allee effects can have significant consequences for small populations and understanding the causal mechanisms for such effects is important for guiding conservation actions. One proposed mechanism is through predation, in which a type II functional response leads to increasing predation rates as prey numbers decline. However, models to support this mechanism have incorporated only a single decl...
Leks often attract predators as well as mates, yet most evolutionary models have assumed that sexual selection, not predation, drives lekking behavior. We explored the influence of predation on lek dynamics using a stochastic dynamic game model based on the lek-breeding greater sage grouse (Centrocercus urophasianus) and its principal avian predator, the golden eagle (Aquila chrysaetos). The mo...
Predators can affect individual fitness and population and community processes through lethal effects (direct consumption or ‘density’ effects), where prey is consumed, or through non-lethal effects (trait-mediated effects or interactions), where behavioural compensation to predation risk occurs, such as animals avoiding areas of high predation risk. Studies of invertebrates, fish and amphibian...
نرخ شکارگری اساس هر پژوهش در برهمکنش شکار-شکارگر است و یکی از اجزای مهم در انتخاب شکارگران در کنترل بیولوژیک بهشمار میرود. نرخ شکارگری کفشدوزکHippodamia variegata (Goeze) با تغذیه از تراکمهای مختلف (20، 40، 60، 80 و 100) عدد از پورههای سن سوم شته پنبه Aphis gossypii Glover در شرایط آزمایشگاهی (1±25 درجه سلسیوس، رطوبت نسبی 5 ±65 درصد و دوره نوری 16 ساعت روشنایی و 8 ساعت تاریکی) بررسی شد. ...
Because competition for resources generally leads to the spatial exclusion of species using similar resources, it is surprising that foreign spider species are frequently observed in or near the nests of the social spider, Anelosimus studiosus (Hentz 1850) (Theridiidae). In this study, we quantified the frequency of A. studiosus-foreign spider co-occurrence and completed experiments designed to...
Predators exert strong top-down pressure on herbivorous insects, but research on how predators affect herbivore fitness often focuses on the more active juvenile and adult life stages while ignoring the pupal or cocoon life stage. Few studies have investigated predation of lepidopteran pupae or cocoons and even fewer have investigated species that are not forest pests. Here we present a study o...
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