The genetic recovery of resistant populations released from pesticide exposure is accelerated by the presence of environmental stressors. By contrast, the relevance of environmental stressors for the spread of resistance during pesticide exposure has not been studied. Moreover, the consequences of interactions between different stressors have not been considered. Here we show that stress throug...

Ecological factors often shape demography through multiple mechanisms, making it difficult to identify the sources of demographic variation. In particular, conspecific density can influence both the strength of competition and the predation rate, but density-dependent competition has received more attention, particularly among terrestrial vertebrates and in island populations. A better understa...

We compared the effect of herbivory by two congeneric specialist weevils (Neochetina eichhorniae and Neochetina bruchi) on competition between their host Eichhornia crassipes and another floating aquatic plant (Pistia stratiotes) by experimentally manipulating plant densities, presence of either or both herbivore species, and nutrient levels. Measurements of E. crassipes yield per original plan...

Theory and empirical evidence show that intraspecific competition can drive selection favouring the use of novel resources (i.e. niche expansion). The evolutionary response to such selection depends on genetic variation for resource use. However, while genetic variation might facilitate niche expansion, genetically diverse groups may also experience weaker competition, reducing density-dependen...

Conditions favoring population divergence in trophic features, such as the low levels of species richness and interspecific competition found on islands, can be similar to conditions that increase their sexual dimorphism or overall variance. Male emberizid sparrows of tidal marshes have undergone parallel evolution of large bills. We tested for parallel increases between dimorphism and overall ...

To determine the role of natural enemies and host-plant quality in the population dynamics of Cameraria hamadryadella. we examined survival patterns and causes of mortality of a single population of C. hamadryadella during the epidemic vcars of 1982-1984 and the endemic years of 198,S-1990. C hamadryadella is a leat-mining microlepidopteran whose primary host is white oak, Quercus alba. Populat...

It is becoming increasingly clear that under natural conditions parasitic infections commonly consist of co-infections with multiple conspecific strains. Multiple-strain infections lead to intraspecific interactions and may have important ecological and evolutionary effects on both hosts and parasites. However, experimental evidence on intraspecific competition or facilitation in infections has...

The biogeographic expansion of modern humans out of Africa began approximately 50,000 years ago. This expansion resulted in the colonization of most of the land area and habitats throughout the globe and in the replacement of preexisting hominid species. However, such rapid population growth and geographic spread is somewhat unexpected for a large primate with a slow, density-dependent life his...

Soldier-producing polyembryonic waSPS are the only social animals that develop as parasites inside the bodies of other insects. Characterizing the kin composition of broods is central to understanding the evolution of the soldier caste in these unique social insects. Here we studied the role of soldiers in mediating the outcome of competition among clones of the polyembryonic wasp Copidosoma fl...

Many empirical studies of ecological community indicate the coexistence of competing species is extremely common in nature. However, many mathematical studies show that coexistence of competitive species is not so easy. In the present article, we focus on the segregation of habitat (microhabitat). If habitats of species are spatially separated, they can coexist easily: under the habitat segrega...