bioRxiv Science⌕ Search

Biology subjects

Costa-Pereira, R.

Publications and source records attributed to Costa-Pereira, R..

4 recordsLinked to original sources

Shaken, not shifted: Genotypic variation tunes how interspecific competition shapes niches

Individual variation in resource use as well as in the response to competitors has been recognized as playing an important role is species interactions. Still, we have as yet little information on whether such responses have a genetic basis as well as on how they affect each other. Here, we tested whether 20 genetically inbred lines of the spider mite Tetranychus evansi vary in their response to a gradient of cadmium concentration within plants as well as in their propensity to reshape niches when facing interspecific competition along this gradient. In absence of interspecific competitors, most lines were negatively affected by cadmium, albeit often in a non-linear fashion. Morevoer, half of the lines exhibited changes in the curvature of the relationship between number of females and cadmium concentration when facing competition with the congeneric T. urticae. Inbred lines also showed a shallower decay in offspring number along the cadmium gradient in presence of interspecific competition. Our findings provide evidence for large, partly genetic, variation in resource use and in the response to interspecific competition in heterogeneous environments. Moreover, we show that genotype responses to interspecific competition is contingent upon their response to an environmental gradient. Together, our results thus emphasize the importance of considering intraspecific variation in responses to interspecific competition, providing novel insights to link intra- and interspecific levels of biodiversity.

ecology↗

Order of arrival promotes coexistence via spatial niche preemption by the weak competitor

Historical contingency, such as the order of species arrival, can modify competitive outcomes via niche modification or preemption. However, how these mechanisms ultimately modify stabilising niche and average fitness differences remains largely unknown. By experimentally assembling two congeneric spider mite species feeding on tomato plants during two generations, we show that order of arrival affects species competitive ability and changes the outcome of competition. Contrary to expectations, order of arrival did not cause positive frequency dependent priority effects. Instead, coexistence was predicted when the inferior competitor (Tetranychus urticae) arrived first. In that case, T. urticae colonised the preferred feeding stratum (leaves) of T. evansi leading to spatial niche preemption, which equalised fitness and reduced niche differences, driving community assembly to a close-to-neutrality scenario. Our study demonstrates how the order of species arrival and the spatial context of competitive interactions can jointly determine whether species can coexist.

ecology↗

Collective behaviour is not robust to disturbance, yet parent and offspring colonies resemble each other in social spiders

Groups of animals possess phenotypes such as collective behaviour, which may determine the fitness of group members. However, the stability and robustness to perturbations of collective phenotypes in natural conditions is not established. Furthermore, whether group phenotypes are transmitted from parent to offspring groups is required for understanding how selection on group phenotypes contributes to evolution, but parent-offspring resemblance at the group level is rarely estimated. We evaluated robustness to perturbation and parent-offspring resemblance of collective foraging aggressiveness in colonies of the social spider Anelosimus eximius. Among-colony differences in foraging aggressiveness were consistent over time but changed if the colony was perturbed through the removal of individuals, or via their removal and subsequent return. Offspring and parent colony behaviour were correlated, but only once the offspring colony had settled after being translocated. The parent-offspring resemblance was not driven by a shared elevation but could be due to other environmental factors. Laboratory collective behaviour was not correlated with behaviour in the field. Colony aggression seems sensitive to initial conditions and easily perturbed between behavioural states. Despite this sensitivity, offspring colonies have collective behaviour that resembles that of their parent colony, provided they are given enough time to settle into the environment.

evolutionary biology↗

Multilevel selection in groups of groups

Natural selection occurs at many levels. We evaluated selection acting on collectives at a level of multilevel selection analysis not yet quantified: within and between clusters of groups. We did so by monitoring the performance of natural colonies of social spiders with contrasting foraging aggressiveness in clusters of various sizes. Within-clusters, growth rates were suppressed when colonies were surrounded by more rival groups, conveying that competition is greater. When colonies were surrounded by few rivals, the more aggressive colonies in a cluster were more successful. In contrast, relatively non-aggressive colonies performed better when surrounded by many rivals. Patterns of selection between-clusters depended on the performance metric considered, but cluster-wide aggressiveness was always favored in small clusters. Together, selection both within-and between natural clusters of colonies was detectable, but highly contingent on the number of competing colonies.

evolutionary biology↗