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DEMODIV: Bridging the gap between demography and diversification: Insights from an evolutionary radiation of grasshoppers
Our understanding about the foremost proximate mechanisms driving the formation and persistence of independently evolving lineages (i.e., species) is still tremendously limited. This could be in part due to the scarce integration of microevolutionary processes into macroevolutionary inference, which has hampered our capacity to identify the ecological and evolutionary phenomena that jointly operate to shape current patterns of biological diversity. A potential way to fill this gap is integrating accurate estimates of key demographic and evolutionary processes operating at microevolutionary scales within macroevolutionary inference frameworks. Research in this direction is promising but still at its early infancy. The increased capacity to generate large genomic datasets in non-model organisms and the continuous development of versatile analytical approaches allows us now to infer evolutionary and demographic parameters at an unprecedented resolution. As a result, we can now confidentially estimate the timing and magnitude of demographic fluctuations, infer rates of gene flow among populations, and determine the occurrence, extent, direction and timing of hybridization. All these phenomena are presumed to be closely associated with opportunity of species formation and lineage persistence, but formal evaluation of their impacts on rates of species formation is still very limited.
The goal of DEMODIV is to shed light on the microevolutionary processes underlying rates of species formation, with particular emphasis on studying the demographic controls on this phenomenon. Using as study system a radiation of grasshoppers, the central hypothesis that will be tested in this project is that speciation rates are explained by species-specific population and hybridization dynamics, two microevolutionary processes intimately linked to the four major controls of speciation: population isolation, population persistence, evolution of reproductive barriers, and evolutionary novelty. These hypothetical rate-limiting controls of speciation are likely to be of particular importance in the context of Pleistocene climatic oscillations, in which recurrent phases of population expansion/contraction provided ample opportunity for both divergence and gene flow at different stages along the continuum of speciation. Specifically, DEMODIV aims to integrate genomic data and detailed information on taxon-specific ecological and phenotypic attributes to: (i) test across landscape replicates how the interplay between dispersal ability and niche breadth impact the demographic trajectories of species to shape their spatial patterns of genetic and phenotypic diversification (Objective 1); (ii) identify the processes contributing to the genetic cohesiveness of species in hotspots of diversification in which geographical contact and opportunities for hybridization among several closely related taxa might be frequent over evolutionary time (Objective 2); (iii) analyse whether rates of speciation estimated at the tips of the phylogeny are explained by species-specific population and hybridization dynamics and determine how these processes are impacted by the interaction between biotic and abiotic parameters identified as key drivers of geographical diversification at microevolutionary timescales (Objective 3). In addressing these core questions, DEMODIV aims to bridge the gap between micro- and macroevolutionary phenomena in order to gain new insights into the processes that generate biological diversity.
SCHEMATIC OF DEMODIV
2. Ortego J, Kaya S, Çıplak B, Knowles LL (2024) Microgeographic speciation in a complex of Anatolian bush crickets facilitated by fast evolution of reproductive isolation. Journal of Evolutionary Biology, in press. [PDF]
1. Noguerales V, Ortego J (2022) Genomic evidence of speciation by fusion in a recent radiation of grasshoppers. Evolution, 76: 2618-2633. [PDF] [Digest by Sean Stankowski - PDF]
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