Landscape Population Genomics of Forsythia (Forsythia suspensa) Reveal That Ecological Habitats Determine the Adaptive Evolution of Species

Abstract

Understanding the genetic mechanisms of adaptation to environmental variables is a key concern in molecular ecology and evolutionary biology. Determining the adaptive evolutionary direction and evaluating the adaptation status of species can improve our understanding of these mechanisms. In this study, we sampled 20 populations of Forsythia suspensa to infer the relationship between environmental variables and adaptive genetic variations. Population structure analysis revealed that four genetic groups of F. suspensa exist resulting from divergent selection driven by seven environmental variables. A total of 26 outlier loci were identified by both BayeScan and FDIST2, 23 of which were environment-associated loci (EAL). Environmental association analysis revealed that the environmental variables related to the ecological habitats of F. suspensa are associated with high numbers of EAL. Results of EAL characterization in F. suspensa are consistent with the hypothesis that ecological habitats determine the adaptive evolution of this species. Moreover, a model of species adaptation to environmental variables was proposed in this study. The adaptation model was used to further evaluate the adaptation status of F. suspensa to environmental variables. This study will be useful to help us in understanding the adaptive evolution of species in regions lacking strong selection pressure.

Genetic variability and structure of an important wild steppe grass Psathyrostachys juncea (Triticeae: Poaceae) germplasm collection from north and central Asia

“…The genetic structure of species is affected by the interaction of multiple factors, such as the transmission model of seeds and pollen, population demographic history, geological events, geographical or ecological barriers and divergent selection of environmental factors (Yang et al, 2017;Ohsawa & Ide, 2008). While a strong gene flow (N m > 1) may weaken the segregation of species, the hierarchical structure of P. juncea revealed by AFLPs here could scarcely be ascribed to gene drift or inbreeding (Sui et al, 2009;Clark, Wentworth & O'Malley, 2000;Slatkin, 1993).…”

“…To conserve and exploit the genetic resources of plants scientifically, a detailed acquaintance of the distribution and amount of genetic variability within the organism is demanded, mainly focused on the investigation of the population genetic diversity and hierarchical structure (Feng, Jiang & Fan, 2015;Costa et al, 2016). A heavily researched subject in evolutionary biology and molecular ecology is the investigation of the genetic basis of local adaptation in non-model species in natural plant populations (Di Pierro et al, 2017;Yang et al, 2017). Adaptive divergence driven by seasonal climate change and habitat heterogeneity can result in local adaptation (Yang et al, 2017;Hedrick, 2006).…”

“…A heavily researched subject in evolutionary biology and molecular ecology is the investigation of the genetic basis of local adaptation in non-model species in natural plant populations (Di Pierro et al, 2017;Yang et al, 2017). Adaptive divergence driven by seasonal climate change and habitat heterogeneity can result in local adaptation (Yang et al, 2017;Hedrick, 2006). In addition to environmental differences, geographic isolation, phylogeographic patterns, gene flow and population dynamics also lead to selective pressures resulting in spatially structured genetic variation.…”

Ten Years of Landscape Genomics: Challenges and Opportunities

“…However, most non-model species do not have established genomic information to appropriately place sufficient markers across the genome. Therefore, two characteristics, i.e., no requirement for a priori genome knowledge and a high covering density in genomes, are indispensable for the use of these molecular markers in landscape genomics ( Yang et al, 2017 ).…”

Landscape genomics analysis of Achyranthes bidentata reveal adaptive genetic variations are driven by environmental variations relating to ecological habit

“…The typical regional vegetation consists of deciduous broadleaved forest (DBLF). To date, only two landscape genetics studies of Cotinus coggygria and Forsythia suspensa in this region have been reported (Lei et al 2015;Yang et al 2017). However, these informations are insuicient to understand the adaptive evolution of regional vegetation.…”