Native fruit traits may mediate dispersal competition between native and non-native plants

Seed disperser preferences may mediate the impact of invasive, non-native plant species on their new ecological communities. Significant seed disperser preference for invasives over native species could facilitate the spread of the invasives while impeding native plant dispersal. Such competition for dispersers could negatively impact the fitness of some native plants. Here, we review published literature to identify circumstances under which preference for non-native fruits occurs. The importance of fruit attraction is underscored by several studies demonstrating that invasive, fleshy-fruited plant species are particularly attractive to regional frugivores. A small set of studies directly compare frugivore preference for native vs. invasive species, and we find that different designs and goals within such studies frequently yield contrasting results. When similar native and non-native plant species have been compared, frugivores have tended to show preference for the non-natives. This preference appears to stem from enhanced feeding efficiency or accessibility associated with the non-native fruits. On the other hand, studies examining preference within existing suites of co-occurring species, with no attempt to maximize fruit similarity, show mixed results, with frugivores in most cases acting opportunistically or preferring native species. A simple, exploratory meta-analysis finds significant preference for native species when these studies are examined as a group. We illustrate the contrasting findings typical of these two approaches with results from two smallscale aviary experiments we conducted to determine preference by frugivorous bird species in northern California. In these case studies, native birds preferred the native fruit species as long as it was dissimilar from non-native fruits, while non-native European starlings preferred non-native fruit. However, native birds showed slight, non-significant preference for non-native fruit species when such fruits were selected for their physical resemblance to the native fruit species. Based on our review and case studies, we propose that fruit characteristics of native plant communities could dictate how well a non-native, fleshy-fruited plant species competes for dispersers with natives. Native bird preferences may be largely influenced by regional native fruits, such that birds are attracted to the colors, morphology, and infructescence structures characteristic of preferred native fruits. Non-native fruits exhibiting similar traits are likely to encounter bird communities predisposed to consume them. If those non-natives offer greater fruit abundance, energy content, or accessibility, they may outcompete native plants for dispersers

Flourishing Foliage: Exploring Hail City\u27s Diverse Botanical Landscape

This research explores the role of native plants in enhancing the distinctiveness of cities in Saudi Arabia, focusing on a specific case study of Al-Samra Park. The study aims to investigate the prevalence and effects of non-native and native plants in the park and their contribution to the uniqueness of the landscape. A questionnaire was designed and implemented to gather data, and the park\u27s plant composition was examined. The findings indicate that non-native plants dominate Al-Samra Park, while native plants are scarce. However, the abundance of non-native plants offers various benefits to park visitors. Some non-native plants possess medicinal properties, such as anti-diabetic and detoxifying effects, and provide support for joint health. It is important to exercise caution due to the potential health risks associated with certain non-native plant species. Interestingly, certain non-native plants in the park are harmless and contribute aesthetically to the environment. These plants provide shading and enhance the visual appeal of the area. The research highlights the importance of carefully selecting and incorporating plants, both native and non-native, to strike a balance between aesthetic considerations and potential health implications. The limited presence of native plants raises questions about the preservation and promotion of Saudi Arabia\u27s indigenous flora. Designers and landscapers should consider the significance of native plants in maintaining the Kingdom\u27s identity while ensuring the safe and beneficial integration of non-native species

Non-Native Non-\u3ci\u3eApis\u3c/i\u3e Bees Are More Abundant on Non-Native Versus Native Flowering Woody Landscape Plants

Urban ecosystems can support diverse communities of wild native bees. Because bloom times are conserved by geographic origin, incorporating some non-invasive non-native plants in urban landscapes can extend the flowering season and help support bees and other pollinators during periods when floral resources from native plants are limiting. A caveat, though, is the possibility that non-native plants might disproportionately host non-native, potentially invasive bee species. We tested that hypothesis by identifying all non-native bees among 11,275 total bees previously collected from 45 species of flowering woody landscape plants across 213 urban sites. Honey bees, Apis mellifera L., accounted for 22% of the total bees and 88.6% of the non-native bees in the collections. Six other non-native bee species, accounting for 2.86% of the total, were found on 16 non-native and 11 native woody plant species. Non-Apis non-native bees in total, and Osmia taurus Smith and Megachile sculpturalis (Smith), the two most abundant species, were significantly more abundant on non-native versus native plants. Planting of favored non-native hosts could potentially facilitate establishment and spread of non-Apis non-native bees in urban areas. Our host records may be useful for tracking those bees’ distribution in their introduced geographical ranges

Natural selection on plant resistance to herbivores in the native and introduced range

. When plants are introduced into new regions, the absence of their co-evolved natural enemies can result in lower levels of attack. As a consequence of this reduction in enemy pressure, plant performance may increase and selection for resistance to enemies may decrease. In the present study, we compared leaf damage, plant size and leaf trichome density, as well as the direction and magnitude of selection on resistance and plant size between non-native (Spain) and native (Mexico) populations of Datura stramonium. This species was introduced to Spain about five centuries ago and constitutes an ideal system to test four predictions of the enemy release hypothesis. Compared with native populations, we expected Spanish populations of D. stramonium to have (i) lower levels of foliar damage; (ii) larger plant size; (iii) lower leaf trichome density that is unrelated to foliar damage by herbivores; and (iv) weak or no selection on resistance to herbivores but strong selection on plant size. Our results showed that, on average, plants from non-native populations were significantly less damaged by herbivores, were less pubescent and were larger than those from native populations. We also detected different selection regimes on resistance and plant size between the non-native and native ranges. Positive selection on plant size was detected in both ranges (though it was higher in the non-native area), but consistent positive selection on relative resistance was detected only in the native range. Overall, we suggest that changes in selection pressure on resistance and plant size in D. stramonium in Spain are a consequence of ‘release from natural enemies’

Explaining the variation in impacts of non-native plants on local-scale species richness: the role of phylogenetic relatedness

Aim: To assess how the magnitude of impacts of non-native plants on species richness of resident plants and animals varies in relation to the traits and phylogenetic position of the non-native as well as characteristics of the invaded site.Location: Global.Methods: Meta-analysis and phylogenetic regressions based on 216 studies were used to examine the effects of 96 non-native plant species on species richness of resident plants and animals while considering differences in non-native species traits (life-form, clonality or vegetative reproduction, and nitrogen-fixing ability) and characteristics of the invaded site (ecosystem type, insularity and climatic region).Results: Plots with non-native plants had lower resident plant (–20.5%) and animal species richness (–26.4%) than paired uninvaded control plots. Nitrogen-fixing ability, followed by phylogeny and clonality were the best predictors of the magnitude of impacts of non-native plants on native plant species richness. Non-nitrogen-fixing and clonal non-native plants reduced species richness more than nitrogen-fixing and non-clonal invaders. However, life-form and characteristics of the invaded sites did not appear to be important. In the case of resident animal species richness, only the phylogenetic position of the non-native and whether invaded sites were islands or not influenced impacts, with a more pronounced decrease found on islands than mainlands.Main conclusions: The presence of a phylogenetic signal on the magnitude of the impacts of non-native plants on resident plant and animal richness indicates that closely related non-native plants tend to have similar impacts. This suggests that the magnitude of the impact might depend on shared plant traits not explored in our study. Our results therefore support the need to include the phylogenetic similarity of non-native plants to known invaders in risk assessment analysis

Regional Invasive Species & Climate Change Management Challenge: Why Native? Benefits of planting native species in a changing climate

Yards host a variety of native and non-native plants. It is easy to assume all plants play a similar role in supporting wildlife, but native plants dramatically increase the diversity of bees, butterflies, birds and other native animals. Additionally, non-native plants can become invasive or support invasive pests. Native plants increase biodiversity and reduce risks associated with invasive species, which supports resilient ecosystems in the face of climate change

The role of non-native plants in the integration of non-native phytophagous invertebrates in native food webs

This thesis brings together a series of studies, examining the role of non-native plants in the integration of non-native invertebrates in native food webs. I use data from comprehensive surveys of formally-planted gardens to investigate the efficacy of straightforward measures of non-native plant presence and/or landscape parameters, as reliable predictors of non-native invertebrate presence, finding that non-native invertebrate richness increases with non-native plant species richness, with invertebrates showing a clear preference for woody plants. I then use the context of metapopulation theory to explore the facilitative role of non-native plants in the ability of a non-native invertebrate to persist within a community, finding that where host-plant habitat patches are closer together, the likelihood of a patch being occupied is greater, especially if the patch is occupied but that this effect is not universal, with species-specific effects present also. I then explore the potential for apparent competition, in the form of negative indirect interactions between native and non-native plants mediated by a shared invertebrate enemy, with the indirect interactions biased by plant relatedness, finding that phylogenetically ranked pairwise native/non-native plant interactions are weakly correlated with observed shared invertebrate interactions, while a significant Mantel test result indicates a significant potential for apparent competition. Finally, I test for detectability of apparent competition in a gall wasp community, finding no evidence of apparent competition but potential evidence for the unexpected occurrence of apparent mutualism. Collectively, these findings provide original insight into how non-native plants and non-native invertebrates interact in an ecological community, and how these interactions help to structure the community. Additionally, they have implications for non-native invertebrate species management, from the practical application of ground-level planting decisions to the development of reliable predictive tools

Intra and interspecific competition via allelopathy among native and non-native plants

Invasive non- native species success often is attributed to their competitive superiority, potentially through allelochemical inhibition (allelopathy) of native species, as suggested by the novel weapons hypothesis. However, it is also possible that non- native species are able to be successful through decreased intraspecific competition. Decreased intraspecific competition could be attributed to a lack of genetic variation creating less variable allelopathic effects. I predict that if non- native species follow the novel weapons hypothesis, their allelochemicals will restrict more biomass and give them a competitive edge compared to native species. Additionally, I predict that if non- native species have lower intraspecific genetic variation, non- native species will have less variation of allelopathic effects than natives. Furthermore, if non- native plant invasion is driven by allelopathy, I expect greater inhibitory effects of non- native than native plants. I conducted a greenhouse experiment to compare the competitive allelopathy of the non- native and native plants. This experiment involved assessing the restricted growth of non- native and native plant pairs (shrub or tree) in both intra- and inter-specific competition, with allelochemical extracts applied. Additionally, I conducted a laboratory bioassay experiment to evaluate the variability of allelopathic effects on model seed germination and growth using field- collected non- native and native leaf samples. My results showed little evidence that non- native invasive plants in Western New York possess particular novel or stronger allelopathic effects compared to native plants. Allelopathic effects did not vary based on invasive status, and non- native allelochemicals did not inhibit model seeds more than native allelochemicals. These findings suggest that native allelochemicals could be just as prominent as those from non- native species

Do Native Parasitic Plants Cause More Damage to Exotic Invasive Hosts Than Native Non-Invasive Hosts? An Implication for Biocontrol

Field studies have shown that native, parasitic plants grow vigorously on invasive plants and can cause more damage to invasive plants than native plants. However, no empirical test has been conducted and the mechanism is still unknown. We conducted a completely randomized greenhouse experiment using 3 congeneric pairs of exotic, invasive and native, non-invasive herbaceous plant species to quantify the damage caused by parasitic plants to hosts and its correlation with the hosts' growth rate and resource use efficiency. The biomass of the parasitic plants on exotic, invasive hosts was significantly higher than on congeneric native, non-invasive hosts. Parasites caused more damage to exotic, invasive hosts than to congeneric, native, non-invasive hosts. The damage caused by parasites to hosts was significantly positively correlated with the biomass of parasitic plants. The damage of parasites to hosts was significantly positively correlated with the relative growth rate and the resource use efficiency of its host plants. It may be the mechanism by which parasitic plants grow more vigorously on invasive hosts and cause more damage to exotic, invasive hosts than to native, non-invasive hosts. These results suggest a potential biological control effect of native, parasitic plants on invasive species by reducing the dominance of invasive species in the invaded community

Species richness and phylogenetic diversity of native and non-native species respond differently to area and environmental factors

© 2018 John Wiley & Sons Ltd Aim: To test whether native and non-native species have similar diversity–area relationships (species–area relationships [SARs] and phylogenetic diversity–area relationships [PDARs]) and whether they respond similarly to environmental variables. Location: United States. Methods: Using lists of native and non-native species as well as environmental variables for \u3e250 US national parks, we compared SARs and PDARs of native and non-native species to test whether they respond similarly to environmental conditions. We then used multiple regressions involving climate, land cover and anthropogenic variables to further explore underlying predictors of diversity for plants and birds in US national parks. Results: Native and non-native species had different slopes for SARs and PDARs, with significantly higher slopes for native species. Corroborating this pattern, multiple regressions showed that native and non-native diversity of plants and birds responded differently to a greater number of environmental variables than expected by chance. For native species richness, park area and longitude were the most important variables while the number of park visitors, temperature and the percentage of natural area were among the most important ones for non-native species richness. Interestingly, the most important predictor of native and non-native plant phylogenetic diversity, temperature, had positive effects on non-native plants but negative effects on natives. Main conclusions: SARs, PDARs and multiple regressions all suggest that native and non-native plants and birds responded differently to environmental factors that influence their diversity. The agreement between diversity–area relationships and multiple regressions with environmental variables suggests that SARs and PDARs can be both used as quick proxies of overall responses of species to environmental conditions. However, more importantly, our results suggest that global change will have different effects on native and non-native species, making it inappropriate to apply the large body of knowledge on native species to understand patterns of community assembly of non-native species