Global urban environmental change drives adaptation in white clover.

Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors.

On the ecological significance of pollen color: a case study in American trout lily (Erythronium americanum).

Evolutionary ecologists seek to explain the processes that maintain variation within populations. In plants, petal color variation can affect pollinator visitation, environmental tolerance, and herbivore deterrence. Variation in sexual organs may similarly affect plant performance.

Explaining the apparent paradox of persistent selection for early flowering.

Decades of observation in natural plant populations have revealed pervasive phenotypic selection for early flowering onset. This consistent pattern seems at odds with life-history theory, which predicts stabilizing selection on age and size at reproduction. Why is selection for later flowering rare? Moreover, extensive evidence demonstrates that flowering time can and does evolve.

Photoinactivation of Photosystem II in Prochlorococcus and Synechococcus.

The marine picocyanobacteria Synechococcus and Prochlorococcus numerically dominate open ocean phytoplankton. Although evolutionarily related they are ecologically distinct, with different strategies to harvest, manage and exploit light. We grew representative strains of Synechococcus and Prochlorococcus and tracked their susceptibility to photoinactivation of Photosystem II under a range of light levels.

Estimating selection through male fitness: three complementary methods illuminate the nature and causes of selection on flowering time.

Our understanding of selection through male fitness is limited by the resource demands and indirect nature of the best available genetic techniques. Applying complementary, independent approaches to this problem can help clarify evolution through male function. We applied three methods to estimate selection on flowering time through male fitness in experimental populations of the annual plant Brassica rapa: (i) an analysis of mating opportunity based on flower production schedules, (ii) genetic paternity analysis, and (iii) a novel approach based on principles of experimental evolution.

The causes of selection on flowering time through male fitness in a hermaphroditic annual plant.

Flowering is a key life-history event whose timing almost certainly affects both male and female fitness, but tests of selection on flowering time through male fitness are few. Such selection may arise from direct effects of flowering time, and indirect effects through covariance between flowering time and the environment experienced during reproduction. To isolate these intrinsically correlated associations, we staggered planting dates of Brassica rapa families with known flowering times, creating populations in which age at flowering (i.

What drives selection on flowering time? An experimental manipulation of the inherent correlation between genotype and environment.

The optimal timing of the seasonal switch from somatic growth to reproduction can depend on an individual's condition at reproduction, the quality of the environment in which it will reproduce, or both. In annual plants, vegetative size (a function of age at flowering) affects resources available for seed production, whereas exposure to mutualists, antagonists, and abiotic stresses in the environment (functions of Julian date of flowering) influences success in converting resources into offspring. The inherent tight correlation between age, size, and environment obscures their independent fitness contributions.

Hard and soft selection on phenology through seasonal shifts in the general and social environments: A study on plant emergence time.

The timing of transition out of one life-history phase determines where in the seasonal succession of environments the next phase is spent. Shifts in the general environment (e.g.

Temporal variation in phenotypic gender and expected functional gender within and among individuals in an annual plant.

Background And Aims: Adaptive explanations for variation in sex allocation centre on variation in resource status and variation in the mating environment. The latter can occur when dichogamy causes siring opportunity to vary across the flowering season. In this study, it is hypothesized that the widespread tendency towards declining fruit-set from first to last flowers on plants can similarly lead to a varying mating environment by causing a temporal shift in the quality (not quantity) of siring opportunities.

Broad geographic covariation between floral traits and the mating system in Camissoniopsis cheiranthifolia (Onagraceae): multiple stable mixed mating systems across the species' range?

Background And Aims: Plants vary widely in the extent to which seeds are produced via self-fertilization vs. outcrossing, and evolutionary change in the mating system is thought to be accompanied by genetic differentiation in a syndrome of floral traits. We quantified the pattern of variation and covariation in floral traits and the proportion of seeds outcrossed (t) to better understand the evolutionary processes involved in mating system differentiation among and within populations of the short-lived Pacific coastal dune endemic Camissoniopsis cheiranthifolia across its geographic range in western North America.