Species range limits involve many aspects of evolution and ecology, from species distribution abundance to the niches. Theory suggests myriad processes by which arise, including competitive exclusion, Allee effects, gene swamping; however, most models remain empirically untested. Range are correlated with a number abiotic biotic factors, but further experimentation is needed understand underlying mechanisms. edges characterized increased genetic isolation, differentiation, variability in...

Abstract In plant conservation, restoration (the augmentation or reestablishment of an extinct population community) is a valuable tool to mitigate the loss habitat. However, efforts can result in introduction novel genes and genotypes into populations when materials used are not local origin. This movement potentially important because many species subdivided that adapted environmental conditions. Here we focus on genetic concerns arising from ongoing efforts, where often little known about...

While small-scale studies show that more diverse native communities are less invasible by exotics, at large spatial scales often find positive correlations between and exotic diversity. This large-scale pattern is thought to arise because landscapes with favorable conditions for species also have species. From theory, we proposed an alternative hypothesis: the relationship driven heterogeneity in composition, which environment. Landscapes environment can sustain species, leading a...

Abstract A major goal of population biologists involved in restoration work is to restore populations a level that will allow them persist over the long term within dynamic landscape and include ability undergo adaptive evolutionary change. We discuss five research areas particular importance biology offer potentially unique opportunities couple basic with practical needs restorationists. The are: (1) influence numbers individuals genetic variation initial on colonization, establishment,...

In California, little is known about the sensitivity of native bunchgrasses to competition or changes in resource availability. We investigated effect nonnative annual vegetation on availability and growth a bunchgrass, Nassella pulchra, pair factorial field experiments that incorporated effects both interspecific intraspecific as well variation soil depth. Plots differing target densities neighborhoods were used assess aboveground (light) belowground (water) over multiple seasons two sites...

Abstract Invasive plants can be larger and more fecund in their invasive range than native range, although it is unknown how often this a result of genetically controlled shift traits, plastic response to favourable environment, or combination thereof. Here we present data from common garden experiments that compare the size fecundity California poppies, Eschscholzia californica Cham. Individuals 20 populations, half (native) Chile (invasive), were grown both with without competition other...

According to theory, gene flow marginal populations may stall or aid adaptation at range limits by swamping peripheral with maladaptive enhancing genetic variability and reducing inbreeding depression, respectively. We tested these contrasting predictions manipulating patterns of the annual plant, Mimulus laciniatus , its warm limit. Gene was experimentally applied using crosses within warm-limit (selfed outcrossed), between populations, central across two elevational transects. measured...

The traditional view of the species as fundamental unit evolution has been challenged by observations that in heterogeneous environments, gene flow may be too restricted to overcome effects local selection. Whether a evolves cohesive depends critically on dynamic balance between homogenizing among populations and potentially disruptive adaptation. To examine this evolutionary "global" selection, we studied northern Californian Helianthus exilis, serpentine sunflower, within mosaic...

Abstract High‐impact biological invasions often involve establishment and spread in disturbed, high‐resource patches followed by biotically or abiotically stressful areas. Evolutionary change may be required for the second phase of invasion (establishment areas) to occur. When species have low genetic diversity short selection history, within‐generation phenotypic plasticity is cited as mechanism through which across multiple habitat types can We show that trans‐generational (TGP) result...

Root plasticity, a trait that can respond to selective pressure, may help plants forage for nutrients in heterogeneous soils. Agricultural breeding programs have artificially selected increased yield under comparatively homogeneous soil conditions, potentially decreasing the capacity plasticity crop like barley (Hordeum vulgare). However, effects of domestication on evolution root are essentially unknown. Using split container approach, we examined differences among three levels germplasm...

Plant populations often adapt to local environmental conditions. Here we demonstrate adaptation in two subspecies of the California native annual Gilia capitata using standard reciprocal transplant techniques sites (coastal and inland) over three consecutive years. Subspecies performance each site was measured four ways: probability seedling emergence, early vegetative size (length longest leaf), flowering, total number inflorescences produced per plant. Analysis variables demonstrated...

Abstract Insight into the speed and predictability of local adaptation can be gained by studying organisms, such as invasive species, that have recently expanded their geographical ranges. Common garden studies were designed to address these issues with California poppy, Eschscholzia californica , collected from a wide range environments in both its native (California) (Chile) We found similar patterns plant trait variation along abiotic gradients plants areas. Multivariate analysis...

We used three congeneric annual thistles, which vary in their ability to invade California (USA) grasslands, test whether invasiveness is related differences life history traits. hypothesized that populations of these summer-flowering Centaurea species must pass through a demographic gauntlet survival and reproduction order persist the most invasive (C. solstitialis) might possess unique characteristics. Using idea as conceptual framework, we compared each congener terms (1) seed germination...

In inland California grasslands, the high densities of alien annual species have altered growing environment for native perennial grasses. Using variable-density plots, we measured influence intraspecific competition (conspecifics only) and diffuse (mixed-composition neighborhoods that include conspecifics) on growth survival Nassella pulchra, purple needlegrass. We assessed effects in weeded plots unweeded respectively, across a density gradient N. pulchra plants (16–356 plants/m2). used...

Four California annual grassland species were used to examine the hypothesis that different plant have equivalent competitive effects. We investigated effects of annuals on soil water availability and growth responses blue oak (Quercus douglasii Hook & Arn.) neighbor—induced depletion. Neighborhoods composed from with differing phenology morphology hypothesized show non—equivalent both a per—individual— per—unit—tissue basis. Three introduced winter sown at each three densities (10, 30,...

Seed dormancy models suggest that evaluation of environmental conditions should influence the decision to germinate and waiting for more favourable may increase potential fitness. However, because rapid emergence is often positively correlated with performance survival, an alternative strategy accelerate rate site pre‐emption. This response likely be found in seasonal environments greater resource depletion which early confer a competitive advantage. The experiments reported here perennial...

Abstract Interest in using native grass species for restoration is increasing, yet little known about the ecology and genetics of populations or spatial scales over which seed can be transferred successfully grown. The purpose this study was to investigate genetic structure within among Elymus glaucus order make some preliminary recommendations transfer use revegetation projects. Twenty from California, Oregon, Washington were analyzed allozyme genotype at 20 loci, patterns variation...