Rapid Buildup of Genetic Diversity in Founder Populations of the Gynodioecious Plant Species Origanum vulgare after Semi-Natural Grassland Restoration

Abstract

In most landscapes the success of habitat restoration is largely dependent on spontaneous colonization of plant species. This colonization process, and the outcome of restoration practices, can only be considered successful if the genetic makeup of founding populations is not eroded through founder effects and subsequent genetic drift. Here we used 10 microsatellite markers to investigate the genetic effects of recent colonization of the long-lived gynodioecious species Origanum vulgare in restored semi-natural grassland patches. We compared the genetic diversity and differentiation of fourteen recent populations with that of thirteen old, putative source populations, and we evaluated the effects of spatial configuration of the populations on colonization patterns. We did not observe decreased genetic diversity in recent populations, or inflated genetic differentiation among them. Nevertheless, a significantly higher inbreeding coefficient was observed in recent populations, although this was not associated with negative fitness effects. Overall population genetic differentiation was low (FST = 0.040). Individuals of restored populations were assigned to on average 6.1 different source populations (likely following the ‘migrant pool’ model). Gene flow was, however, affected by the spatial configuration of the grasslands, with gene flow into the recent populations mainly originating from nearby source populations. This study demonstrates how spontaneous colonization after habitat restoration can lead to viable populations in a relatively short time, overcoming pronounced founder effects, when several source populations are nearby. Restored populations can therefore rapidly act as stepping stones and sources of genetic diversity, likely increasing overall metapopulation viability of the study species.

Hidden founder effects: small‐scale spatial genetic structure in recently established populations of the grassland specialist plant Anthyllis vulneraria

“…; Helsen et al . ). These elevated inbreeding coefficients can also become amplified in certain species by an increased chance of biparental inbreeding under a leptokurtic pollen dispersal pattern in populations with strong SGS subpopulation structure (Jones et al .…”

“…100 ha of historical calcareous grassland (Helsen et al . ). Most of these restored grasslands were adjacent to mature calcareous grassland, from which spontaneous dispersal of plant species occurred.…”

“…; Helsen et al . ). This suggests that long‐term establishment success of founder populations cannot be reliably assessed based on the measures of genetic diversity and differentiation alone, but that the extent of SGS within these populations should be evaluated as well.…”

Genetic rescue by distant trees mitigates qualitative pollen limitation imposed by fine‐scale spatial genetic structure

“…For instance, conspecific density critically determines the availability of pollen donors and thus pollination failure due to quantitative pollen limitation (Ashman et al, ; Ghazoul, ). In addition, fine‐scale spatial genetic structuring (FSGS hereafter) within plant populations can influence the quality of the pollination by creating genetic neighbourhoods where individuals exhibit increased kinship (Aizen & Harder, ; Escudero, Iriondo, & Torres, ; Helsen, Jacquemyn, Hermy, Vandepitte, & Honnay, ). In this regard, the existence of long‐distance pollination may provide key pollination services (Castilla et al, ; Jordano, ; Kremen et al, ).…”

Rapid genetic restoration of a keystone species exhibiting delayed demographic response

“…Helsen et al . , ). A landscape genetics approach may also provide insight into the effects of the landscape matrix on gene flow (e.g.…”