Glacial connectivity and current population fragmentation in sky islands explain the contemporary distribution of genomic variation in two narrow-endemic montane grasshoppers from a biodiversity hotspot

Aim Cold‐adapted biotas from mid‐latitudes often show small population sizes, harbour low levels of local genetic diversity and are highly vulnerable to extinction due to ongoing climate warming and the progressive shrinking of montane and alpine ecosystems. In this study, we use a suite of analytic...

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Bibliographic Details
Published in:Diversity & distributions 2021-09, Vol.27 (9), p.1619-1633
Main Authors: Tonzo, Vanina, Ortego, Joaquín
Format: Article
Language:English
Subjects:
Alpine ecosystems
Analysis
approximate Bayesian computation
Archipelagoes
Bayesian analysis
Biodiversity
Biodiversity hot spots
Biological diversity
Climate
Climate change
Climate cycles
Cold
Colonization
Connectivity
Current distribution
ddRAD‐seq
demographic history
Demographics
Demography
Ecological niches
Endangered & extinct species
Environment models
environmental niche modelling
Fragmentation
Gene flow
Genetic diversity
Genetic drift
Genetic research
Genetic structure
Genomics
Glacial periods
Global warming
Grasshoppers
Habitats
Islands
landscape genetics
Mathematical models
Mountain ecology
Mountains
Niche (Ecology)
Niches
Orthoptera
Oscillations
Pleistocene
Pleistocene glaciations
Population
Population genetics
Quaternary
RESEARCH ARTICLE
Species extinction
Statistical analysis
Statistical inference
Taxa
Threatened species
Topography
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Summary:Aim Cold‐adapted biotas from mid‐latitudes often show small population sizes, harbour low levels of local genetic diversity and are highly vulnerable to extinction due to ongoing climate warming and the progressive shrinking of montane and alpine ecosystems. In this study, we use a suite of analytical approaches to infer the demographic processes that have shaped contemporary patterns of genomic variation in Omocestus bolivari and Omocestus femoralis, two narrow‐endemic and red‐listed Iberian grasshoppers forming highly fragmented populations in the sky island archipelago of the Baetic System. Location South‐eastern Iberia. Methods We quantified genomic variation in the two focal taxa and coupled ecological niche models and a spatiotemporally explicit simulation approach based on coalescent theory to determine the relative statistical support of a suite of competing demographic scenarios representing contemporary population isolation (i.e. a predominant role of genetic drift) versus historical connectivity and post‐glacial colonization of sky islands (i.e. pulses of gene flow and genetic drift linked to Pleistocene glacial cycles). Results Inference of spatial patterns of genetic structure, environmental niche modelling and statistical evaluation of alternative species‐specific demographic models within an approximate Bayesian computation framework collectively supported genetic admixture during glacial periods and post‐glacial colonization of sky islands, rather than long‐term population isolation, as the scenario best explaining the current distribution of genomic variation in the two focal taxa. Moreover, our analyses revealed that isolation in sky islands has also led to extraordinary genetic fragmentation and contributed to reduce local levels of genetic diversity. Main conclusions This study exemplifies the potential of integrating genomic and environmental niche modelling data across biological and spatial replicates to determine whether organisms with similar habitat requirements have experienced concerted/idiosyncratic responses to Quaternary climatic oscillations, which can ultimately help to reach more general conclusions about the vulnerability of mountain biodiversity hotspots to ongoing climate warming.
ISSN:1366-9516
1472-4642
DOI:10.1111/ddi.13306