The origin of new homoploid species via hybridization is theoretically difficult because it requires the development of reproductive isolation in sympatry. Nonetheless, this mode is often and carelessly used by botanists to account for the formation of species that are morphologically intermediate with respect to related congeners. Here, I review experimental, theoretical, and empirical studies...

The number of regulations regarding pre-plant soil fumigation is increasing. Buffer zones are required for methyl bromide and chloropicrin applica­ tions. Choosing application blocks, methods, and rates to maximize pro­ fits is becoming a difficult challenge for growers. One consideration is the management of the buffer zone. We consider the costs and returns of using steam for pre-plant soil d...

rangeland ploughing and cultivation using dry land farming crops may be amajor reason for the destruction of natural resources in the semiarid and sub-humid regionswhich may significantly change the composition and reduce the stability of the affectedcommunities. in present research, an abandoned ploughed site was compared with a nearbyreference site in the semiarid rangelands of baharkish, quc...

Plant species, plant community diversity and microbial interactions can significantly impact soil microbial communities, yet there are few data on the interactive effects of plant species and plant community diversity on soil bacterial communities. We hypothesized that plant species and plant community diversity affect soil bacterial communities by setting the context in which bacterial interac...

Polyploidy is a common mode of speciation that can have far-reaching consequences for plant ecology and evolution. Because polyploidy can induce an array of phenotypic changes, there can be cascading effects on interactions with other species. These interactions, in turn, can have reciprocal effects on polyploid plants, potentially impacting their establishment and persistence. Although there i...

We have little synthetic understanding of the characteristics of successful plant invaders, i.e., those that become naturalized. I will make, however, three observations about the characteristics of these species: 1) If considered collectively, their morphologic, genetic, and ecological characteristics in many regions (including Hawai`i) are as diverse as the characteristics of the native vascu...

This article describes a multidimensional, multivariate, and multilevel approach to the assessment of nicotine withdrawal. In this prospective study, 70 adult smokers assigned to an active or placebo nicotine patch condition completed multiple daily assessments using an electronic diary. Average and individual growth curves were estimated for affective and nonaffective withdrawal symptoms. All ...