Phylogenetic niche conservatism and plant diversification in South American subtropical grasslands along multiple climatic dimensions

Abstract

Phylogenetic niche conservatism can be investigated at multiple scales on an explicit geographical context. Haplotype-based comparative analyses of lineages occupying the same region, and thus subjected to similar environmental factors, allow decoupling shared evolutionary and ecological patterns, as well as multiple dimensions of adaptive diversification. Here we aimed to assess the role of environmental drivers on diversification of subtropical grassland, based on haplotypic diversity of two plant genera. We sampled two closely related and co-distributed grassland plant genera, Petunia and Calibrachoa, across their entire distribution area. Eigenvectors extracted from pairwise distances based on chloroplast DNA haplotypes were used to fit Phylogenetic Signal-Representation (PSR) curves to estimate evolutionary patterns in 19 bioclimatic variables and altitude. The PSR curves showed that altitude, precipitation, and temperature variables changed at different rates with haplotype differentiation. Altitude and temperature traits evolved under conditions closer to a neutral dynamics, whereas precipitation traits differentiated following more complex models. Our results indicated that the diversification in the two genera was more limited by precipitation conditions. Based on these novel findings, we suggest that future studies should test the possible impact of precipitation variables on the process of ecological differentiation in these genera.

Contrasting results of multiple species delimitation approaches cause uncertainty in synecological studies: A case study on Sri Lankan chafers

“…In consequence, basis for the comparative analysis (i.e. PCoA, clustering) was the amount of divergence alone resulting often in a dendrogram‐based presentation of the outcome in unresolved polytomies of entities (see Figure 4, Figure S3): this makes haplotypes a poor proxy for compositional comparison of species diversity, at least in hyperdiverse and ancient tropical habitats (Barros et al, 2020; Cruz‐Salazar et al, 2021; Rodríguez et al, 2015), for which shared entities are highly informative and should be considered. Haplotypes are simply products of divergence, species often carry more than a single haplotype (or can be even heteroplasmic: i.e.…”

Population genomics indicates micro‐refuges and riverine barriers for a southern South American grassland nightshade

“…Our results revealed that the P. parodii evolutionary history agrees with the proposal for ancient lineages (Avise, 2000). The ancestor of the Petunia genus has originated in the Pampa, and the Quaternary climate shifts strongly influenced its species distribution and diversification (Barros et al, 2015(Barros et al, , 2020Ramos-Fregonezi et al, 2015;Reck-Kortmann et al, 2014), with posterior migration to the north and higher elevations (Backes et al, 2019;Lorenz-Lemke et al, 2010).…”

Isotopic niches do not follow the expectations of niche conservatism in the bird genus Cinclodes

“…Examples of PNC in particular traits abound across multiple taxa including birds (Khaliq et al, 2015; Lovette & Hochachka, 2006), mammals (Cooper et al, 2011; da Silva et al, 2020), frogs (Hu et al, 2016; Pyron et al, 2015; Vidal‐García & Keogh, 2017), insects (D'Agostino et al, 2022; Dorey et al, 2020; Morinière et al, 2016) and plants (Ackerly, 2009; Barros et al, 2020; Folk et al, 2019; Kerkhoff et al, 2014; Kolanowska et al, 2017). Current tests of niche conservatism often examine the degree to which traits follow the phylogenetic history of a given group (Cooper et al, 2010; Münkemüller et al, 2015), but usually lack a comparative framework.…”