Evidence for an evolutionary history of overcompensation in the grassland biennial Gentianella campestris (Gentianaceae)

Article Abstract:

Simulated grazing can have a positive effect on the lifetime seed production of the strict biennial herb Gentianella campestris. It is shown that overcompensation occurs in populations exposed to a high risk of damage but not in those wherein the risk of damage is predictably low. Overcompensation pertains to higher vegetative productivity and seed yield as a consequence of natural or simulated grazing. These and previous results show that the capacity for overcompensation is an adaptive trait with an evolutionary history associated with habitats with a high and predictable risk of damage.

Environmental aspects, Adaptation (Physiology), Physiological adaptation, Grazing, Herbs

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Stabilization of mixed-mating systems by differences in the magnitude of inbreeding depression for male and female fitness components

Article Abstract:

A numerical analysis of a model in which selfing rate is controlled by a single locus having two alleles, designated A and a, was conducted. The selfing rates of genotypes AA, Aa and aa were designated s1,s2 and s3. One limitation of the model is that it did not allow for the joint evolution of inbreeding depression as selfing rate evolved. Results demonstrate that relaxing the assumption of equal inbreeding-depression effects greatly changes the dynamics of mating system evolution by permitting evolutionary stability of mixed-mating systems.

Inbreeding

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Why are unisexual flowers associated with wind pollination and unspecialized pollinators?

Article Abstract:

It is observed that unisexual flowers are more frequent among wind- and water-pollinated species compared to those pollinated by animals. Although this condition holds for dioecy and monoecy, no specific explanations for such behavior have been established. One possibility is that wind pollinated plants have no need for grouped stamens and carpals in a single flower. It is also suggested that the absence of selectivity in terms of floral rewards may explain pollination effects.

Flowers, Pollination

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