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Tobner C.M.,University of Quebec at Montreal | Paquette A.,University of Quebec at Montreal | Reich P.B.,University of Minnesota | Reich P.B.,University of Western Sydney | And 4 more authors.
Oecologia | Year: 2014

Increasing concern about loss of biodiversity and its effects on ecosystem functioning has triggered a series of manipulative experiments worldwide, which have demonstrated a general trend for ecosystem functioning to increase with diversity. General mechanisms proposed to explain diversity effects include complementary resource use and invoke a key role for species' functional traits. The actual mechanisms by which complementary resource use occurs remain, however, poorly understood, as well as whether they apply to tree-dominated ecosystems. Here we present an experimental approach offering multiple innovative aspects to the field of biodiversity-ecosystem functioning (BEF) research. The International Diversity Experiment Network with Trees (IDENT) allows research to be conducted at several hierarchical levels within individuals, neighborhoods, and communities. The network investigates questions related to intraspecific trait variation, complementarity, and environmental stress. The goal of IDENT is to identify some of the mechanisms through which individuals and species interact to promote coexistence and the complementary use of resources. IDENT includes several implemented and planned sites in North America and Europe, and uses a replicated design of high-density tree plots of fixed species-richness levels varying in functional diversity (FD). The design reduces the space and time needed for trees to interact allowing a thorough set of mixtures varying over different diversity gradients (specific, functional, phylogenetic) and environmental conditions (e.g., water stress) to be tested in the field. The intention of this paper is to share the experience in designing FD-focused BEF experiments with trees, to favor collaborations and expand the network to different conditions. © 2013 Springer-Verlag Berlin Heidelberg.

Poisot T.,University of Quebec at Rimouski | Poisot T.,Quebec Center for Biodiversity science
F1000Research | Year: 2013

Measuring the modularity of networks, and how it deviates from random expectations, important to understand their structure and emerging properties. Several measures exist to assess modularity, which when applied to the same network, can return both different modularity values (i.e. different estimates of how modular the network is) and different module compositions (i.e. different groups of species forming said modules). More importantly, as each optimization method uses a different optimization criterion, there is a need to have an a posteriori measure serving as an equivalent of a goodness-of-fit. In this article, I propose such a measure of modularity, which is simply defined as the ratio of interactions established between members of the same modules vs. members of different modules. I apply this measure to a large dataset of 290 ecological networks representing host-parasite (bipartite) and predator-prey (unipartite) interactions, to show how the results are easy to interpret and present especially to a broad audience not familiar with modularity analyses, but still can reveal new features about modularity and the ways to measure it. © 2013 Poisot T.

Moses M.,University of the West Indies | Umaharan P.,University of the West Indies | Dayanandan S.,Concordia University at Montreal | Dayanandan S.,Quebec Center for Biodiversity science
Genetic Resources and Crop Evolution | Year: 2014

Capsicum chinense Jacq., one of the five domesticated species of pepper grown in the New World, is a major contributor to both local and international markets and the economy of the Caribbean islands. The planning and implementation of germplasm conservation and breeding programs for the sustainable use of C. chinense genetic resources are hampered by the poor understanding of the genetic structure and diversity of C. chinense in the region. In the present study, the genetic structure, diversity and relatedness of C. chinense germplasm collections within the Caribbean basin and South America were assessed using nuclear microsatellite markers. C. chinense accessions (102) representing seven geographical regions were genotyped using nine polymorphic nuclear microsatellite markers along with 16 accessions representing four other species of Capsicum. The results revealed that the highest genetic diversity (He = 0.58) was found in the Amazon region supporting the postulated center of diversity of C. chinense as the Amazon basin. The cluster analysis resulted in two distinct genetic clusters corresponding to Upper Amazon and Lower Amazon regions, suggesting two independent domestication events or two putative centers of diversity in these regions respectively. The cluster analysis further revealed that populations in Central America and the Caribbean may have been primarily derived from progenitors from Upper Amazon region and later diverged through geographical isolation. Conservation and germplasm collection programs should therefore target these genetically distinct clusters and satellite populations, towards supporting breeding programs to harness heterosis. © 2013 Springer Science+Business Media Dordrecht.

Poisot T.,University of Quebec at Rimouski | Gravel D.,Quebec Center for Biodiversity science
PeerJ | Year: 2014

Connectance and degree distributions are important components of the structure of ecological networks. In this contribution, we use a statistical argument and simple network generating models to show that properties of the degree distribution are driven by network connectance.We discuss the consequences of this finding for (1) the generation of random networks in null-model analyses, and (2) the interpretation of network structure and ecosystem properties in relationship with degree distribution. ©2014 Poisot et al.

Hobaiter C.,University of St. Andrews | Poisot T.,University of Quebec at Rimouski | Poisot T.,Quebec Center for Biodiversity science | Zuberbuhler K.,University of St. Andrews | And 4 more authors.
PLoS Biology | Year: 2014

Social network analysis methods have made it possible to test whether novel behaviors in animals spread through individual or social learning. To date, however, social network analysis of wild populations has been limited to static models that cannot precisely reflect the dynamics of learning, for instance, the impact of multiple observations across time. Here, we present a novel dynamic version of network analysis that is capable of capturing temporal aspects of acquisition—that is, how successive observations by an individual influence its acquisition of the novel behavior. We apply this model to studying the spread of two novel tool-use variants, “moss-sponging” and “leaf-sponge re-use,” in the Sonso chimpanzee community of Budongo Forest, Uganda. Chimpanzees are widely considered the most “cultural” of all animal species, with 39 behaviors suspected as socially acquired, most of them in the domain of tool-use. The cultural hypothesis is supported by experimental data from captive chimpanzees and a range of observational data. However, for wild groups, there is still no direct experimental evidence for social learning, nor has there been any direct observation of social diffusion of behavioral innovations. Here, we tested both a static and a dynamic network model and found strong evidence that diffusion patterns of moss-sponging, but not leaf-sponge re-use, were significantly better explained by social than individual learning. The most conservative estimate of social transmission accounted for 85% of observed events, with an estimated 15-fold increase in learning rate for each time a novice observed an informed individual moss-sponging. We conclude that group-specific behavioral variants in wild chimpanzees can be socially learned, adding to the evidence that this prerequisite for culture originated in a common ancestor of great apes and humans, long before the advent of modern humans. © 2014 Hobaiter et al.

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