The exact nature of the relationship among species range sizes, speciation, and extinction events is not well understood. The factors that promote larger ranges, such as broad niche widths and high dispersal abilities, could increase the likelihood of encountering new habitats but also prevent local adaptation due to high gene flow. Similarly, low dispersal abilities or narrower niche widths could cause populations to be isolated, but such populations may lack advantageous mutations due to low population sizes. Here we present a large-scale, spatially explicit, individual-based model addressing the relationships between species ranges, speciation, and extinction. We followed the evolutionary dynamics of hundreds of thousands of diploid individuals for 200,000 generations. Individuals adapted to multiple resources and formed ecological species in a multidimensional trait space. These species varied in niche widths, and we observed the coexistence of generalists and specialists on a few resources. Our model shows that species ranges correlate with dispersal abilities but do not change with the strength of fitness trade-offs; however, high dispersal abilities and low resource utilization costs, which favored broad niche widths, have a strong negative effect on speciation rates. An unexpected result of our model is the strong effect of underlying resource distributions on speciation: in highly fragmented landscapes, speciation rates are reduced.

Distributional similarity (congruence) between phylogenetically independent taxonomic groups has important biogeographical as well as conservation implications. When multiple groups show congruence, one or two of them can be used as surrogates of diversity in others; thus, simplifying some of the challenges of area prioritization for conservation action. Here we test for congruence in complementarity between amphibians, reptiles and birds across seven tropical rainforest sites in the Eastern Himalaya and Indo-Burma global biodiversity hotspots. The results show that while frogs and lizards are strongly congruent with each other, birds as a whole do not show congruence with either of them. However, certain bird subgroups delineated on the basis of broad ecological niche and life history attributes are significantly congruent with both frogs and lizards. Multiple Mantel regression between environmental variable and species distribution dissimilarity matrices indicate that along with differential response to between-site ecological differences, inherent lifehistory characteristics shared by certain groups contributes to observed patterns of congruence. Our analyses indicate that examining biologically distinct subsets of larger groups can improve the resolution of congruence analyses. This approach can refine area-prioritization initiatives by revealing fine-scale discordances between otherwise concordant groups, and vice versa. Given that monetary resources do not always allow inclusion of multiple groups in biodiversity inventorying efforts, performing such analyses also makes economic sense because it can provide better resolution even with single-group data. In the context of conservation in North-east India, the results highlight the biogeographical complexity of the region, and also point at future priorities for biodiversity inventorying and conservation prioritization, both in terms of areas as well as taxonomic groups.

Invasive alien species continue to threaten global biodiversity. CRISPR-based gene drives, which can theoretically spread through populations despite imparting a fitness cost, could be used to suppress or eradicate pest populations. We develop an individual-based, spatially explicit, stochastic model to simulate the ability of CRISPR-based homing and X chromosome shredding drives to eradicate populations of invasive house mice (Mus muculus) from islands. Using the model, we explore the interactive effect of the efficiency of the drive constructs and the spatial ecology of the target population on the outcome of a gene-drive release. We also consider the impact of polyandrous mating and sperm competition, which could compromise the efficacy of some gene-drive strategies. Our results show that both drive strategies could be used to eradicate large populations of mice. Whereas parameters related to drive efficiency and demography strongly influence drive performance, we find that sperm competition following polyandrous mating is unlikely to impact the outcome of an eradication effort substantially. Assumptions regarding the spatial ecology of mice influenced the probability of and time required for eradication, with short-range dispersal capacities and limited mate-search areas producing 'chase' dynamics across the island characterized by cycles of local extinction and recolonization by mice. We also show that highly efficient drives are not always optimal, when dispersal and matesearch capabilities are low. Rapid local population suppression around the introduction sites can cause loss of the gene drive before it can spread to the entire island.We conclude that, although the design of efficient gene drives is undoubtedly critical, accurate data on the spatial ecology of target species are critical for predicting the result of a gene-drive release.