Landscape and climatic features drive genetic differentiation processes in a South American coastal plant

Abstract

Background Historical and ecological processes shape patterns of genetic diversity in plant species. Colonization to new environments and geographical landscape features determine, amongst other factors, genetic diversity within- and differentiation between-populations. We analyse the genetic diversity and population structure of Calibrachoa heterophylla to infer the influence of abiotic landscape features on the level of gene flow in this coastal species of the South Atlantic Coastal Plain. Results The C. heterophylla populations located on early-deposited coastal plain regions show higher genetic diversity than those closer to the sea. The genetic differentiation follows a pattern of isolation-by-distance. Landscape features, such as water bodies and wind corridors, and geographical distances equally explain the observed genetic differentiation, whereas the precipitation seasonality exhibits a strong signal for isolation-by-environment in marginal populations. The estimated levels of gene flow suggest that marginal populations had restricted immigration rates enhancing differentiation. Conclusions Topographical features related to coastal plain deposition history influence population differentiation in C. heterophylla. Gene flow is mainly restricted to nearby populations and facilitated by wind fields, albeit without any apparent influence of large water bodies. Furthermore, differential rainfall regimes in marginal populations seem to promote genetic differentiation.

Genomic Analyses of Wild and Cultivated Bacanora Agave (Agave angustifolia var. pacifica) Reveal Inbreeding, Few Signs of Cultivation History and Shallow Population Structure

“…Moreover, those sites were also differentiated from each other, a fact that may also explain non- linearity in Mantel tests. Coastal regions have unique environmental characteristics, such as high salinity, greater availability of atmospheric moisture, wind strength and tidal influence, therefore constituting distinct landscapes with unique abiotic and biotic composition [ 61 , 62 ]. We therefore hypothesize that different selection regimes occurring across populations in the coastal environment may be responsible for the observed differentiation.…”

Neutral and outlier single nucleotide polymorphisms disentangle the evolutionary history of a coastal Solanaceae species

“…Depa06 occupies an area that is inserted into the Barrier‐Lagoon II (c. 325 kya), and these individuals inhabit the freshwater coast of Patos Lagoon, whereas Depa07 individuals grow on soils from the Barrier‐Lagoon IV (c. 7–8 kya), the newest available SACP region (Tomazelli et al, 2000) and close to the sea coast. In general, populations from the marginal distribution have shown high genetic differentiation (Palma‐Silva et al, 2009; Pinheiro et al, 2011; Salgueiro et al, 2004; Silva‐Arias et al, 2017, 2021). Based on neutral markers, such differentiation and structure in newly colonized areas depend on local demographic patterns (Klopfstein et al, 2006), and populations from these areas could be influenced by local bottlenecks (Hofer et al, 2012).…”

“…Additionally, we used a matrix (9) with the coast‐distance matrix between geographic points, accounting for mean wind speed and predominant direction (WIND). In this matrix, we included information from 2011 to 2016 from meteorological stations throughout the SACP (Silva‐Arias et al, 2021) that includes the year when the individuals were collected for the genetic analysis. We compared the nine models containing a single predictor variable and the predictor variables' combination with a null model.…”

“…Each SACP portion or area (Figure 1f) has different seasonality and winds blowing in different directions, influencing the sand dunes' mobility (Bigarella et al, 2005). In general, the northern region has strong winds from South to Northwest; the central region, which is mostly affected by stronger winds (17 m/s) that blow from the East to West; and the southern region that has the weakest regime of winds, mostly from blowing from the South to Northwest direction (Figure 1f; Silva-Arias et al, 2021). The SACP belongs to the Pampa ecosystem, but the grasslands in SACP differ from the typical Pampa mainly due to the high salinity and other soil components and prostrate grasses and other decumbent herbaceous plants dominate these coastal vegetation (Menezes et al, 2015).…”

Genomic analyses of wild and cultivated bacanora agave (Agave angustifoliavar.pacifica) reveal inbreeding, few signs of cultivation history and shallow population structure

“…Moreover, those sites were also differentiated from each other, the fact that also may explain non-linearity in Mantel tests. Coastal regions have unique environmental characteristics, such as high salinity, greater availability of atmospheric moisture, wind strength and tidal influence, therefore constituting distinct landscapes with unique abiotic and biotic composition [57,58]. We therefore hypothesize that different selection regimes occurring across populations in the coastal environment may be responsible for the observed differentiation.…”