Metacommunity dynamics over 16 years in a pyrogenic shrubland.

Metacommunity theory allows predictions about the dynamics of potentially interacting species' assemblages that are linked by dispersal, but strong empirical tests of the theory are rare. We analyzed the metacommunity dynamics of Florida rosemary scrub, a patchily distributed pyrogenic community, to test predictions about turnover rates, community nestedness, and responses to patch size, arrangement, and quality. We collected occurrence data for 45 plant species from 88 rosemary scrub patches in 1989 and 2005 and used growth form, mechanism of regeneration after fire, and degree of habitat specialization to categorize species by life history.

Pollen performance of Raphanus sativus (Brassicaceae) declines in response to elevated [CO(2)].

Although increases in atmospheric [CO(2)] are known to affect plant physiology, growth and reproduction, understanding of these effects is limited because most studies of reproductive consequences focus solely on female function. Therefore, we examined the effects of CO(2) enrichment on male function in the annual Raphanus sativus. Pollen donors grown under elevated [CO(2)] initially sired a higher proportion of seeds per fruit than ambient [CO(2)]-grown plants when each was tested against two different standard competitors; however, by the end of the 5-month experiment, these pollen donors sired fewer seeds than ambient [CO(2)]-grown plants and produced a lower proportion of viable pollen grains.

The impact of plant and flower age on mating patterns.

Background: Over a season, plant condition, amount of ongoing reproduction and biotic and abiotic environmental factors vary. As flowers age, flower condition and amount of pollen donated and received also vary. These internal and external changes are significant for fitness if they result in changes in reproduction and mating.

Microhabitat distribution of two Florida scrub endemic plants in comparison to their habitat-generalist congeners.

Habitat-specialist species may be restricted to a narrower range of microhabitats than habitat-generalist species. We addressed this hypothesis by comparing microhabitats of two pairs of congeners that differ in habitat specificity and co-occur in one distinct habitat type, Florida rosemary scrub. We characterized microhabitats of rosemary scrub specialists, Polygonella basiramia and Lechea cernua, their habitat-generalist congeners, Polygonella robusta and Lechea deckertii, and random points in the rosemary scrub habitat.