The role of niche breadth in oak phylogeography: Quercus glaucoides as a study case

Abstract

Aim:The extent of genetic diversity and its distribution among populations have been associated with species attributes such as mating system, dispersal ability and geographic range size. Another attribute that could contribute to intraspecific phylogeographic patterns is niche breadth, but this has rarely been tested. Here, we ask whether a Mexican oak with a comparatively narrow climatic niche breadth has distinct genetic diversity patterns compared to other codistributed oaks with a broader climatic niche. Location: Mexico.Taxon: Quercus glaucoides M. Martens & Galeotti (Fagaceae).Methods: Descriptors of genetic diversity and structure were calculated for 21 Q. glaucoides populations using chloroplast DNA (cpDNA) and nuclear microsatellites (nSSRs).Historical demographic dynamics were inferred with approximate Bayesian computation (ABC) and past potential distribution models. To test for an association between niche breadth and phylogeographic patterns, we used genetic diversity and differentiation values of Q. glaucoides plus those previously published for 10 other Mexican oak taxa. Niche breadth was estimated for all taxa and linear regressions were performed.Results: Genetic diversity calculated from nSSRs (H O = 0.539; H E = 0.714) was among the lowest and cpDNA differentiation (N ST = 0.88) was the highest so far obtained for comparable Mexican oaks. Moderate changes in demographic size and distribution shifts throughout the last glacial cycle were inferred, explaining some of the observed genetic patterns. A positive correlation of H O and a negative correlation of N ST with niche breadth were detected across taxa.Main Conclusions: Distinct phylogeographic patterns in Q. glaucoides could be explained because a narrower niche may cause lower historical effective population sizes and more fragmented distributions in comparison to species with a wider niche breadth, even with similar range sizes. Our results indicate that niche breadth would be an interesting ecological attribute to be included in future comparative phylogeographic studies.

Nuclear and chloroplast DNA phylogeography reveals high genetic diversity and postglacial range expansion in Quercus mexicana

“…In Mexico, the geographical location, complex topography, dynamics of the tectonic and climatic history of the Mexican highlands have influenced the evolutionary history of montane species (Mastretta‐Yanes et al, 2015). Some phylogeographic studies have provided important evidence on species demographic history and population structure in Mexican oaks (González‐Rodríguez et al, 2004; Ramos‐Ortiz et al, 2016; Hipp et al, 2018, 2020; Rodríguez‐Gómez et al, 2018; Albarrán‐Lara et al, 2019; McCauley et al, 2019; Peñaloza‐Ramírez et al, 2020; Gaytán‐Legaria et al, 2023). Here, our results indicate a genetic and phylogeographical structure of Q. mexicana , evidence of a demographic expansion in some populations of the species, and a more extensive current distribution than that in the past.…”

“…In the Mexican highlands, several oak species have high genetic diversity but low genetic structure, reflecting historical population processes characterized by considerable range stability, elevational displacements, and dynamic gene flow between populations (González‐Rodríguez et al, 2004; Tovar‐Sánchez et al, 2008; Rodríguez‐Correa et al, 2015; Ramos‐Ortiz et al, 2016; Rodríguez‐Gómez et al, 2018; Albarrán‐Lara et al, 2019; McCauley et al, 2019; Peñaloza‐Ramírez et al, 2020; Gaytán‐Legaria et al, 2023). However, within the complex topography of Mexico, the distribution patterns of tree species reflect the formation of specific plant communities for each biogeographic region.…”