Low genetic diversity contrasts with high phenotypic variability in heptaploid Spartina densiflora populations invading the Pacific coast of North America

Abstract

Species can respond to environmental pressures through genetic and epigenetic changes and through phenotypic plasticity, but few studies have evaluated the relationships between genetic differentiation and phenotypic plasticity of plant species along changing environmental conditions throughout wide latitudinal ranges. We studied inter‐ and intrapopulation genetic diversity (using simple sequence repeats and chloroplast DNA sequencing) and inter‐ and intrapopulation phenotypic variability of 33 plant traits (using field and common‐garden measurements) for five populations of the invasive cordgrass Spartina densiflora Brongn. along the Pacific coast of North America from San Francisco Bay to Vancouver Island. Studied populations showed very low genetic diversity, high levels of phenotypic variability when growing in contrasted environments and high intrapopulation phenotypic variability for many plant traits. This intrapopulation phenotypic variability was especially high, irrespective of environmental conditions, for those traits showing also high phenotypic plasticity. Within‐population variation represented 84% of the total genetic variation coinciding with certain individual plants keeping consistent responses for three plant traits (chlorophyll b and carotenoid contents, and dead shoot biomass) in the field and in common‐garden conditions. These populations have most likely undergone genetic bottleneck since their introduction from South America; multiple introductions are unknown but possible as the population from Vancouver Island was the most recent and one of the most genetically diverse. S. densiflora appears as a species that would not be very affected itself by climate change and sea‐level rise as it can disperse, establish, and acclimate to contrasted environments along wide latitudinal ranges.

Genetic diversity and genetic structure of Decalobanthus boisianus in Hainan Island, China

“…These results are consistent with the previous reports from other invasive species like Carduus acanthoides L. (Bohumil, Petr, Dana, Petr, & Ivana, ), Ambrosia artemisiifolia L. (Kočiš et al, ), and Spartina densiflora Brongn. (Castillo et al, ) but are less than most clonal invasive species, such as Eupatorium catarium Veldkamp (Li, Li, & Liu, ), Praxelis clematidea R.M.King & H.Rob. (Wang, Huang, Downie, Chen, & Chen, ), Galinsoga quadriradiata Ruiz & Pav.…”

Contrasting plant adaptation strategies to latitude in the native and invasive range of Spartina alterniflora

“…Second, geographic gradients in abiotic conditions might lead to the evolution of altered vegetative and reproductive traits or novel latitudinal clines (Bossdorf et al, 2005;Colautti et al, 2009;Colautti & Lau, 2015;Hodgins et al, 2018). An important invasive mechanism is phenotypic plasticity, which allows the form and function of an organism to match the environmental variation encountered in a new environment without genetic modification (Richards et al, 2006;Davidson et al, 2011;Castillo et al, 2018). Preadaptation is another mechanism facilitating invasion by which there is an incidental match of a genetically distinct subset of phenotypes to the particular introduced environments (Maron et al, 2004;Dlugosch & Parker, 2007).…”

Transgressivity in Key Functional Traits Rather Than Phenotypic Plasticity Promotes Stress Tolerance in A Hybrid Cordgrass

“…Trait Var. = (X max − X min ) × 100 X max (1) Mean intra-population trait variability index was calculated for each taxon as the arithmetic average (n = 12 inundation x salinity treatments) of the relation between the difference between the maximum (x max ) and the minimum (x min ) values divided by the maximum of a given plant trait at each salinity x inundation combination [40]. The intra-population trait variability was used as an intrinsic indicator of trait variation within populations.…”

“…and their F-1 sterile hybrid S. densiflora x foliosa from San Francisco Estuary on the central California coast, USA [23,39]. Both parental species show low genetic diversity in the studied salt marshes [40,41], and their habitats are expected to be substantially impacted by climate change and SLR [30]. We analyzed 36 biochemical, physiological, morphological, and fitness-related traits of the hybrid S. densiflora x foliosa in relation to its co-occurring parental species in a mesocosm experiment, in which the three taxa were subjected to the combined effects of salinity, inundation, and their interactions.…”