The ecological significance of spacing among plants in contributing to the maintenance of species richness, particularly in tropical forests, has received considerable attention that has largely focussed on distance- and density-dependent seed and seedling mortality. More recently it has become apparent that plant spacing is also relevant to pollination, which often constrains seed production. ...

It is increasingly recognized that microbiota affect host health and physiology. However, it is unclear what factors shape microbiome community assembly in nature, and how microbiome assembly can be manipulated to improve host health. All plant leaves host foliar endophytic fungi, which make up a diverse, environmentally acquired fungal microbiota. Here, we experimentally manipulated assembly o...

The correspondence between allozymic variation and specific differentiation was studied in four populations corresponding to the three nominal, allopatric species of clam genus Eurhomalea (E. rufa, E. lenticularis, E. exalbida) described for southern South America. Allozyme variation scored in 12 loci was high as indicated by heterozygosity levels (15.8-20.7 %) and by the presence of only three...

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Reproductive character displacement is the adaptive evolution of traits that minimize deleterious reproductive interactions between species. When arising from selection to avoid hybridization, this process is referred to as reinforcement. Reproductive character displacement generates divergence not only between interacting species, but also between conspecific populations that are sympatric wit...

Estradiol plays an important role in mediating changes in female sexual behavior across reproductive cycles. In the túngara frog [Physalaemus (=Engystomops) pustulosus], the relationship between gonadal activity and female sexual behavior, as expressed by phonotaxis, is mediated primarily by estradiol. Estradiol receptors are expressed in auditory and motivational brain areas and the hormone co...

In Experiment 1, hooded rats (Rattus norvegicus) were exposed to a novel diet in a food dish or on a conspecific; they were allowed to consume the same diet and then were injected with a toxin LiCl. Later both groups ate more of the novel diet than animals that had not been exposed, and the conspecific-exposed group ate more than the dish-exposed group. Reducing aversion learning by exposure on...

In social mammals, the presence of an affiliative conspecific reduces stress responses, a phenomenon referred to as "social buffering."In a previous study, we found that the presence of a conspecific animal ameliorated a variety of stress responses to an aversive conditioned stimulus (CS), including freezing and Fos expression in the lateral amygdala (LA) of male rats. Although these findings s...

Leaf-cutting ants of the genus Atta have highly size-polymorphic workers, and size is related to division of labor. We studied trail-following behavior of different-sized workers in a laboratory colony of Atta vollenweideri. For small and large workers, we measured responsiveness and preference to artificial conspecific and heterospecific pheromone trails made from poison gland extracts of A. v...