Connecting genomic patterns of local adaptation and niche suitability in teosintes

Abstract

The central abundance hypothesis predicts that local adaptation is a function of the distance to the centre of a species' geographic range. To test this hypothesis, we gathered genomic diversity data from 49 populations, 646 individuals and 33,464 SNPs of two wild relatives of maize, the teosintes Zea mays ssp. parviglumis and Zea. mays. ssp. mexicana. We examined the association between the distance to their climatic and geographic centroids and the enrichment of SNPs bearing signals of adaptation. We identified candidate adaptive SNPs in each population by combining neutrality tests and cline analyses. By applying linear regression models, we found that the number of candidate SNPs is positively associated with niche suitability, while genetic diversity is reduced at the limits of the geographic distribution. Our results suggest that overall, populations located at the limit of the species' niches are adapting locally. We argue that local adaptation to this limit could initiate ecological speciation processes and facilitate adaptation to global change.

Phylogeographic and population genetic analyses ofCucurbita moschatareveal divergence of two mitochondrial lineages linked to an elevational gradient

“…The BAPS analysis also supported two main clusters: rather than a subdivision among geographic areas, these two clusters highlighted a clear altitudinal cline (Appendix S3). As previously mentioned, similar patterns of genetic structure between highland and lowland landraces have been noted in other domesticated taxa (e.g., maize and barley; Tanto et al, 2010;Van Heerwaarden et al, 2011); and genomic analyses have uncovered signals of local adaptation to these altitudinal gradients (Aguirre-Liguori et al, 2017;Fustier et al, 2017). Divergence in highland and lowland, together with human dispersal over large areas (Besnard et al, 2013), could explain the current wide geographic-altitudinal tolerance of C. moschata (Lira, 1995).…”

“…To understand how C. moschata adapts to lowland and highland environments, local adaptation should be studied with genomic approaches—for instance, scanning single‐nucleotide polymorphisms related to environmental parameters of their distribution, as for example conducted recently in wild maize by Aguirre‐Liguori et al. (, , b).…”

Adaptive phenotypic divergence in an annual grass differs across biotic contexts*

“…; Aguirre‐Liguori et al. ) and would be expected to generate differences in total additive genetic variation but not G matrix orientation (Roff ; Puentes et al. ), but see Steppan et al.…”

The combined use of raw and phylogenetically independent methods of outlier detection uncovers genome‐wide dynamics of local adaptation in a lizard

“…However, an obvious question is why new genetic variants (CIOA) have evolved in Lerma when this population already had the ancestral genetic variation (at ROA loci highly homozygous in the west) that could be selected to warrant local adaptation to western‐like habitat. This paradox may hide a more complex scenario in which environmental gradients are multidimensional, with other factors (such as predators, parasites, or competitors) affecting the dynamics of local adaptation besides the forest‐to‐open gradient driving the divergence between the two lineages (Aguirre‐Liguori et al, ; Levinst, ). After all, if only one dimension of environmental variation is considered, moving away from one end of the gradient inevitably leads to approaching the other end (Lahti et al, ).…”