Historical Range Expansion Determines the Phylogenetic Diversity Introduced During Contemporary Species Invasion

Abstract

For a species rapidly expanding its geographic range, such as during biological invasion, most alleles in the introduced range will have their evolutionary origins in the native range. Yet, the way in which historical processes occurring over evolutionary time in the native range contribute to the diversity sampled during contemporary invasion is largely unknown. We used chloroplast DNA (cpDNA) gene genealogies and coalescent methods to study two congeneric plants, Silene latifolia and S. vulgaris. We examined how phylogenetic diversity was shaped by demographic growth and historical range expansions in the native European range, and how this history affected the diversity sampled during their recent invasion of North America. Genealogies from both species depart from neutrality, likely as a result of demographic expansion in the ancestral range, the timing of which corresponds to shortly after each species originated. However, the species differ in the spatial distribution of cpDNA lineages across the native range. Silene latifolia shows a highly significant phylogeographic structure that most likely reflects different avenues of the postglacial expansion into northern Europe from Mediterranean refugia. By contrast, cpDNA lineages in S. vulgaris have been widely scattered across Europe during, or since, the most recent post-glacial expansion. These different evolutionary histories resulted in dramatic differences in how phylogenetic diversity was sampled during invasion of North America. In S. latifolia, relatively few, discrete invasion events from a structured native range resulted in a rather severe genetic bottleneck, but also opportunities for admixture among previously isolated lineages. In S. vulgaris, lack of genetic structure was accompanied by more representative sampling of phylogenetic diversity during invasion, and reduced potential for admixture. Our results provide clear insights into how historical processes may feed forward to influence the phylogenetic diversity of species invading new geographic ranges.

Patterns of cyto-nuclear linkage disequilibrium in Silene latifolia: genomic heterogeneity and temporal stability

“…S. latifolia was introduced to North America relatively recently, ca. 200 years ago (Taylor and Keller, 2007). Following multiple, likely separate, introductions to both the Eastern and Western coasts of North America, the introduced range of S. latifolia expanded rapidly (Taylor and Keller, 2007;Keller et al, 2009).…”

“…Given that the nuclear and cytoplasmic genomes are not physically linked, in purely outcrossing species like S. latifolia, the accumulation of LD must be due either to epistatic selection or neutral demographic processes associated with the history of population structure (for example, founder effects). These founder effects could include ongoing local events that occur regularly in metapopulations (McCauley, 1994;McCauley et al, 1996;McCauley, 1997;Keller et al, 2012), or historical processes including the species post-glacial history of range expansion (Taylor and Keller, 2007).…”

Adaptation and colonization history affect the evolution of clines in two introduced species

“…Silene vulgaris is gynodioecious, with self-compatible hermaphrodites and a mixed-mating system (Glaettli et al, 2006), whereas S. latifolia is dioecious. Both species have evolutionary histories of dynamic range expansion, becoming widespread following post-glacial expansion throughout their native range in Eurasia (Taylor & Keller, 2007). The species were first reported in North America in the early 1800s, probably introduced from Europe as contaminant in clover seed and waste from ocean-going ships that deposited their ballast (soil, sand, gravel, silage) in North American port cities (Martindale, 1876;Baker, 1948;McNeill, 1977).…”

Constructing Standard Invasion Curves from Herbarium Data—Toward Increased Predictability of Plant Invasions

“…Molecular biology techniques can provide valuable data to recreate invasive species routes, and there is an extensive body of literature demonstrating this (e.g., Keller et al 2012;Taylor and Keller 2007). Indeed, some researchers have used genetic analyses in conjunction with herbarium data to look for hybridization events, study evolutionary trajectories, or identify a species' geographic origin, although not specifically to generate invasion curves.…”