Maternal effects of plant competition: Comparing introduced populations to their native counterparts

Background/Question/Methods

Parents growing in stressful conditions have compromised fitness and may confer this stress to its offspring through paternal and maternal effects.  In plants, response to intraspecific competition can delay life-history events, fitness and response to selection.  A species may have varied response to stress across its range however, as populations are constantly evolving and may develop varied trade-offs between competitiveness versus the ability to spread and reproduce.  We present how early life-history traits vary across a weedy species range and how these traits are modified by the maternal environment quality.  Using seeds harvested from mothers grown under different levels of intraspecific competition, we use a common garden to grow populations from three ranges and determine the effect of maternal competition on offspring early life-history traits.

Results/Conclusions

We observed varying responses to maternal competition levels within a species: Early life-history offspring performance varied both the direction and strength of response varies by population.  Differences in traits to competition may be explained by genetic variation, adaptive provisioning, or varied trade-off adaptation between competitiveness and maternal fecundity.  We also found that early life-history traits were heritable, when mothers grew without competition.  Our results indicate maternal effects of competition are present, but the expression is not equal by all populations and should be considered when modeling population dynamics across a species range.  Additionally, these findings suggest that some populations in the introduced ranges have adapted increased competitive abilities and negative maternal effects are minimized when grown in competition unlike populations in the native range.