Shift in ecological strategy helps marginal populations of shepherd's purse (Capsella bursa-pastoris) to overcome a high genetic load.

Orsucci M, Milesi P, Hansen J, Girodolle J, Glémin S, Lascoux M

Proc. Biol. Sci. 287 (1927) 20200463 [2020-05-27; online 2020-05-20]

The outcome of species range expansion depends on the interplay of demographic, environmental and genetic factors. Self-fertilizing species usually show a higher invasive ability than outcrossers but selfing and bottlenecks during colonization also lead to an increased genetic load. The relationship between genomic and phenotypic characteristics of expanding populations has, hitherto, rarely been tested experimentally. We analysed how accessions of the shepherd's purse, Capsella bursa-pastoris, from the colonization front or from the core of the natural range performed under increasing density of competitors. First, accessions from the front showed a lower fitness than those from the core. Second, for all accessions, competitor density impacted negatively both vegetative growth and fruit production. However, despite their higher genetic load and lower absolute performances, accessions from the front were less affected by competition than accessions from the core. This seems to be due to phenotypic trade-offs and a shift in phenology that allow accessions from the front to avoid competition.

Pascal Milesi

SciLifeLab Fellow

PubMed 32429810

DOI 10.1098/rspb.2020.0463

Crossref 10.1098/rspb.2020.0463

pmc: PMC7287375
Dryad: 10.5061/dryad.vt4b8gtp7
figshare: 10.6084/m9.figshare.c.4955732

Publications 9.5.0