Data from: Population divergence along lines of genetic variance and covariance in the invasive plant Lythrum salicaria in eastern North America

Evolution during biological invasion may occur over contemporary
timescales, but the rate of evolutionary change may be inhibited by a lack
of standing genetic variation for ecologically relevant traits and by
fitness trade-offs among them. The extent to which these genetic
constraints limit the evolution of local adaptation during biological
invasion has rarely been examined. To investigate genetic constraints on
life-history traits, we measured standing genetic variance and covariance
in 20 populations of the invasive plant purple loosestrife (Lythrum
salicaria) sampled along a latitudinal climatic gradient in eastern North
America and grown under uniform conditions in a glasshouse. Genetic
variances within and among populations were significant for all traits;
however, strong intercorrelations among measurements of seedling growth
rate, time to reproductive maturity and adult size suggested that fitness
trade-offs have constrained population divergence. Evidence to support
this hypothesis was obtained from the genetic variance–covariance matrix
(G) and the matrix of (co)variance among population means (D), which were
79.8% (95% C.I. 77.7–82.9%) similar. These results suggest that population
divergence during invasive spread of L. salicaria in eastern North America
has been constrained by strong genetic correlations among life-history
traits, despite large amounts of standing genetic variation for individual
traits.