and Applied Analysis 3 Combining 1.1 and 1.2 , we see that the Watkinson model of the annual plants is given by the difference equation N n 1 λN n 1 aN n γ λmN n , n 0, 1, 2, . . . . 1.3 In this model the density-independent mortality is not included and the growth of the population occurs only during the vegetative phase of the life cycle. Watkinson in 18 assumed that density-independent morta...

Trade-offs among traits are important for maintaining biodiversity, but the role of natural selection in their construction is not often known. It is possible that trade-offs reflect fundamental constraints, negative correlational selection, or directional selection operating on costly, redundant traits. In a Sonoran Desert community of winter annual plants, we have identified a trade-off betwe...

Plants show phenological responses to herbivory. Some enclosure experiments have demonstrated that the onset of the peak flowering season is dependent on grazing pressure. We constructed a mathematical model using Pontryargin's maximum principle to investigate changes in flowering time by examining shifts in resource allocation from vegetative to reproductive plant components. We represented a ...

(1) Neighbourhood experiments were used to compare the magnitudes of competitive effect and competitive response using all pairwise combinations of Papaver rhoeas, Triticum aestivum and Avena sativa as neighbour species, and these three species plus Chenopodium album as target species. (2) Over 79% of the variance in target weight was explained by a simple hyperbolic function of neighbour weigh...

The effects of interand intraspecific interference on size hierarchies (size inequalities) were investigated in populations of the annual plants Trifolium incarnatum and Lollurn mult~florurn. Variables experimentally manipulated included plant density, species proportions, soil fertility. and spatial pattern of plantings. Densities were below those for extensive density-dependent mortality. Siz...

Masting is defined as the intermittent highly variable production of seed in a plant population. According to reproductive modes, that is, sexual and asexual reproduction, masting species can be separated into three groups, that is, (1) species, for example, bamboo, flower only once before they die; (2) species, for example, Fagus, reproduce sexually; and (3) species, for example, Stipa tenacis...

F-box proteins are generally responsible for substrate recognition in the Skp1-Cullin-F-box complexes that are involved in protein degradation via the ubiquitin-26S proteasome pathway. In plants, F-box genes influence a variety of biological processes, such as leaf senescence, branching, self-incompatibility, and responses to biotic and abiotic stresses. The number of F-box genes in Populus (Po...