The demographic trajectories of organisms – including geographical diversification and allopatric speciation – are the outcome of the interplay between biotic (e.g., dispersal capacity, niche breadth, interspecific interactions) and abiotic (e.g., climate changes, topography, environmental heterogeneity) factors that synergistically determine their range dynamics and processes of population fragmentation-expansion. In this seminar, Joaquín Ortego will present some of his recent research on grasshoppers from the Mediterranean region aimed at better understanding some aspects of the demographic and evolutionary dynamics of alpine and montane biotas from different perspectives and at contrasting spatiotemporal/evolutionary scales. His talk will include some of his latest and ongoing work on (i) interglacial speciation in relictual alpine grasshoppers that currently form extremely fragmented populations in sky islands, (ii) the microevolutionary consequences of recent transitions to flightlessness, and (iii) concerted demographic responses to Quaternary climatic oscillations in a species assemblage of alpine grasshoppers.