Life history variation in the heavy metal tolerant plant Thlaspi caerulescens growing in a network of contaminated and noncontaminated sites in southern France: role of gene flow, selection and phenotypic plasticity

Abstract

Summary• Here we explore life history differences in a set of neighbouring metallicolous and nonmetallicolous populations of the heavy metal tolerant plant Thlaspi caerulescens .• We contrasted data from field observations and from a common garden experiment, in which soil zinc (Zn) concentration and light availability were manipulated, and data on microsatellite molecular variation.• The two ecotypes showed few differences in life history in the field, but large differences in their response to Zn concentration in the common garden. Soil toxicity affected most characters in nonmetallicolous plants, while it had no effect on metallicolous plants. The two ecotypes responded similarly to light. Genetic differentiation for quantitative characters between ecotypes contrasted with the absence of differentiation for microsatellites. Conversely, populations of the same ecotype showed similar responses to Zn, despite their high differentiation for molecular markers.• We conclude that divergent selection related to soil toxicity has had a predominant role in shaping life history differences between ecotypes, gene flow weakly opposing local adaptation despite geographical proximity.

Historical connectivity, contemporary isolation and local adaptation in a widespread but discontinuously distributed species endemic to Taiwan, Rhododendron oldhamii (Ericaceae)

“…A pattern of restricted dispersal of R. oldhamii could have been caused by small effective population sizes or possibly by the short distance Rhododendron seeds can disperse (Hirao, 2010) and ineffective pollen flow (Marshall et al, 2010), resulting in the beginning of reproductive isolation, and this may have facilitated within-population mating because of fragmentation and population divergence (Jiménez-Ambriz et al, 2007). Environmental variables might have played roles as selective forces, enforcing population adaptive divergence, in rapidly evolving small populations of R. oldhamii even when selection was weak.…”

“…Therefore, geographic variations in flowering rhythms of R. oldhamii suggest population isolation caused by reduced gene flow among populations. Evidence suggests a direct relationship between natural selection and assortative mating resulting from differences in flowering times (Jiménez-Ambriz et al, 2007), and local adaptations associated with flowering time genes have also been reported (Keller et al, 2011(Keller et al, , 2012.…”

Evolution of nickel hyperaccumulation and serpentine adaptation in the Alyssum serpyllifolium species complex

“…Although it is generally believed that the emergence of the hyperaccumulation trait in these two model species was driven by, and coincident with, the appearance of anthropogenic metal-polluted sites in the mining regions of Europe (Pauwels et al, 2006;Jiménez-Ambriz et al, 2007;Besnard et al, 2009), recent research on A. halleri supports a much more ancient appearance of the trait-or at least selection on major genes responsible for the trait-during the speciation process giving rise to this lineage hundreds of thousands of years ago, and thus pre-dating any human industrial activity (Roux et al, 2011). It has been suggested that major loci involved in metal tolerance and accumulation, such as the HMA4 gene (encoding the plasma membrane ATPase responsible for transporting Zn 2+ out of root cells for loading into the xylem and translocation to the shoot), were targets of selection early in the history of the species (Pauwels et al, 2005;Roux et al, 2011).…”

Adaptive Species Differentiation and Population Uniformity in Viola Species Sharing Similar Geographical Distribution but Differing Habitat Preferences

“…Examples include Scabiosa canescens (Waldmann & Andersson, 1998), Liatris scariosa var. novae-angliae (Gravuer, von Wettberg, & Schmitt, 2005), Cedrela odorata (Navarro et al, 2005), Thlaspi caerulescens (Jimenez-Ambriz et al, 2007) and Brassica insularis and Centaurea corymbosa (Petit et al, 2001). Petit et al (2001) suggested that restricted ecological niches could cause species to experience homogenous selection pressures, resulting in a lower Q ST .…”