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opencc-zeroDec 2021View details →

Non-native species drive biotic homogenization, but it depends on the realm, beta diversity facet and study design: A meta-analytic systematic review

While reducing the species richness of invaded communities is a well-known consequence of biological invasions, non-native species can also reduce variability between communities over time (i.e., beta diversity) in a process known as biotic homogenization. Although biotic homogenization due to non-native species is a common topic of theoretical reviews, we believe no global meta-analysis on the effect of non-native species on beta diversity has been carried out yet. Here, we systematically show that non-native species drive biotic homogenization, but it depends on the realm, beta diversity facet and study design. Biotic homogenization was more intense in marine and freshwater ecosystems than in terrestrial ecosystems. We also found that non-native species reduced both taxonomic and phylogenetic beta diversity, but not the functional beta diversity. Finally, we observed more intense effects using "before vs. after invasion" followed by "uninvaded vs. invaded sites" while the effect size of studies using "communities associated with native vs. non-native species" did not differ from zero. Our findings highlight that non-native species contribute to biotic homogenization as a prevalent pattern in communities worldwide, and that biodiversity conservation strategies should go beyond investigating the reduction in the number of species by also taking into account beta diversity in its multiple facets.

opencc-zeroJan 2022View details →

Nectar values from: Turnover in floral composition explains species diversity and temporal stability in the nectar supply of urban residential gardens

Residential gardens are a valuable habitat for insect pollinators worldwide, but differences in individual gardening practices substantially affect their floral composition. It is important to understand how the floral resource supply of gardens varies in both space and time so we can develop evidence-based management recommendations to support pollinator conservation in towns and cities. We surveyed 59 residential gardens in the city of Bristol, UK, at monthly intervals from March to October. For each of 472 garden surveys, we combined floral abundances with nectar sugar data to quantify the nectar production of each garden, investigating the magnitude, temporal stability, and diversity and composition of garden nectar supplies. We found that individual gardens differ markedly in the quantity of nectar sugar they supply (from 2 g to 1662 g), and nectar production is higher in more affluent neighbourhoods, but not in larger gardens. Nectar supply peaks in July (mid-summer), when more plant taxa are in flower, but temporal patterns vary among individual gardens. At larger spatial scales, temporal variability averages out through the portfolio effect, meaning insect pollinators foraging across many gardens in urban landscapes have access to a relatively stable and continuous supply of nectar through the year. Turnover in species composition among gardens leads to an extremely high overall plant richness, with 636 taxa recorded flowering. The nectar supply is dominated by non-natives, which provide 91% of all nectar sugar, while shrubs are the main plant life form contributing to nectar production (58%). Two thirds of nectar sugar is only available to relatively specialised pollinators, leaving just one third that is accessible to all. Synthesis and applications. By measuring nectar supply in residential gardens, our study demonstrates that pollinator-friendly management, affecting garden quality, is more important than the size of a garden, giving every gardener an opportunity to contribute to pollinator conservation in urban areas. For gardeners interested in increasing the value of their land to foraging pollinators we recommend planting nectar-rich shrubs with complementary flowering periods and prioritising flowers with an open structure in late summer and autumn.

opencc-zeroJan 2022View details →

Data from: Turnover in floral composition explains species diversity and temporal stability in the nectar supply of urban residential gardens

opencc-zeroDec 2016View details →

Data from: Genetic diversity and divergence in the fountain darter (Etheostoma fonticola): implications for conservation of an endangered species

The endangered fountain darter Etheostoma fonticola is found only in the Comal and San Marcos rivers in the Guadalupe River basin in central Texas, USA. Comal River fountain darters were believed to be extir- pated following a severe drought in the 1950s and were reintroduced in the early 1970s using 457 darters from the San Marcos River. In this study we used 23 microsatellite loci to describe and evaluate the genetic diversity, population structure and effective population size (Ne) of fountain darters. We also evaluated the genetic effect of the Comal River reintroduction and the influence of low-head dams (dams) on dispersal in both rivers. Bayesian analysis of individual genotypes and Analysis of Molecular Variation supported two distinct populations concordant with the two rivers. Estimates of Ne were much smaller (<10 %) than census size (Nc) in both rivers but did not indicate the populations are at risk of an immediate and rapid loss of genetic diversity. Coalescent-based estimates of the genetically effective number of founders (Nf) for the Comal River averaged about 49 darters and, together with the indices of genetic diversity and the bottleneck test (heterozygosity excess) results, were consistent with a founder event following the reintroduction in the Comal River. Finally, our results regarding the influence of dams on fountain darter dispersal were equivocal and did not support a conclusion. We recommend this issue be examined further as part of the fountain darter recovery program.

opencc-zeroFeb 2022View details →

Data for: Habitat diversity, resource availability, and island age in the species-area relationship

Aim: The island species-area relationship (ISAR) and its theoretical justifications assume the area of islands to be homogeneous across an archipelago, which is generally not the case. We compare the performance of models that adjust or substitute for island area with measures of habitat diversity, island age, and resource availability to account for the violation of this assumption. We further compare the performance of models for two taxonomic groups. Location: Five hotspot archipelagos (Azores, Galapagos, Hawaii, Cape Verde, Canary Islands). Taxa: Vascular plants and birds. Methods: We used the mathematical framework of the power law to compare relevant models, treating the one containing only area as a null model against which others were compared. Data was collated from the GIFT database and from the literature. Models were compared using linear regression within archipelagos and via mixed effect models with archipelago as a random effect. Results: Weighting of island area by habitat diversity and resource availability systematically improved statistical significance and model fits versus the area only power law. Models including island age did not show the same systematic improvement in model fits. For vascular plants, weighting islands by resource availability (energy and water) performed better than weighting by habitat diversity, although for birds these weightings performed equally well. Main Conclusions: Given that islands within archipelagos are fairly uniform in climate, topography, and geology, it is worth accounting for this in ISARs. Our results suggest that, for islands in volcanic hotspot archipelagos this is best done by using direct measures of habitat diversity and resource availability rather than using island age as a proxy. Because weighting area by habitat diversity and resource availability produced better predictors of species diversity, the proposed approach may be particularly valuable in conservation science.

opencc-zeroMar 2022View details →

Moving beyond the diversity paradox: the limitations of competition-based frameworks in understanding species diversity

Over the last century, ecologists have attempted to understand patterns of species diversity by showing stable coexistence arising from a baseline expectation of competitive exclusion. This expectation stems from an explicit assumption of resource scarcity and implicit assumptions of Malthusian struggle and winner-take-all dynamics. Fidelity to the competitive exclusion principle (CEP) presents species diversity as a paradox: if species compete for limited resources, how can they coexist? In this essay, we investigate the contradiction between the theoretical expectation of competitive exclusion and the empirical prevalence of multispecies communities. We trace the persistence of the CEP in ecological research despite numerous challenges and explore publishing trends suggesting that this framework has resulted in a disproportionate focus on competition and exclusion in contemporary research. From a critical science studies perspective, we analyze the sociopolitical factors that have contributed to these patterns. We argue that we must excavate the ideological foundation upon which competition-based coexistence research has been built to move beyond the current perceived "diversity paradox." To that end, we propose shifting the functional null hypothesis of coexistence research, introducing the notion of a "coexistence principle," which positions the persistence of multispecies communities as the rule rather than the exception in nature.

opencc-zeroMar 2022View details →

Reduced genetic diversity associated with the northern expansion of an amphibian species with high habitat-specialization, Ascaphus truei, resolved using two types of genetic markers

Reconstruction of historical relationships between geographic regions within a species' range can indicate dispersal patterns and help predict future responses to shifts in climate. Ascaphus truei (coastal tailed frog) is an indicator species of the health of forests and perennial streams in the Coastal and Cascade Mountains of the Pacific Northwest of North America. We used two genetic techniques — microsatellite and genotype-by-sequencing (GBS) — to compare the within region genetic diversity of populations near the northern extent of the species' range (British Columbia, Canada) to two geographic regions in British Columbia and two in Washington, USA, moving towards the core of the range. Allelic richness and heterozygosity declined substantially as latitude increased. The northernmost region had the lowest mean expected heterozygosities for both techniques (microsatellite, M = 0.20, SE = 0.080; GBS, M = 0.025, SE = 0.0010) and the southernmost region had the highest (microsatellite, M = 0.88, SE = 0.054; GBS, M = 0.20, SE = 0.0029). The northernmost regions (NC and MC) clustered together in population structure models for both genetic techniques. Our discovery of reduced diversity may have important conservation and management implications for population connectivity and the response of A. truei to climate change.

opencc-zeroMar 2022View details →

Amphibian diversity in the Amazonian floating meadows: a Hanski core-satellite species system (scripts and codes)

The Amazon catchment is the largest river basin on earth, and up to 30% of its waters flow across floodplains. In its open waters, floating plants known as floating meadows abound. They can act as vectors of dispersal for their associated fauna and, therefore, can be important for the spatial structure of communities. Here, we focus on amphibian diversity in the Amazonian floating meadows over large spatial scales. We recorded 50 amphibian species over 57 sites, covering around 7,000 km along river courses. Using multi-site generalised dissimilarity modelling of zeta diversity, we tested Hanski's core-satellite (HCS) hypothesis and identified the existence of two functional groups of species operating under different ecological processes in the floating meadows. 'Core' species are associated with floating meadows, while 'satellite' species are associated with adjacent environments, being only occasional or accidental occupants of the floating vegetation. At large scales, amphibian diversity in floating meadows is mostly determined by stochastic processes, whereas at regional scales, climate and deterministic processes are central drivers. Compared with the turnover of 'core' species, the turnover of 'satellite' species increases much faster with distances and is also controlled by a wider range of climatic features. Distance is not a limiting factor for 'core' species, suggesting that they have a stronger dispersal ability even over large distances. This is probably related to the existence of passive long-distance dispersal of individuals along rivers via vegetation rafts. In this sense, Amazonian rivers can serve as corridors, facilitating dispersal especially for species associated with riverine habitats such as floating meadows.

opencc-by-4.0Nov 2021View details →

Fig. 1 in Effect Of Farming And Rainfall On The Species Diversity, Population Density And Community Structure Of Birds Breeding In The Kalahari Woodland, Ne Namibia

Fig. 1. The location of the transect (indicated with red arrow).

opencc-by-4.0Nov 2021View details →

Fig. 2 in Effect Of Farming And Rainfall On The Species Diversity, Population Density And Community Structure Of Birds Breeding In The Kalahari Woodland, Ne Namibia

Fig. 2. Monthly rainfall in Katima Mulilo in 2014 and 2015.

opencc-by-4.0Nov 2021View details →

Fig. 4 in Effect Of Farming And Rainfall On The Species Diversity, Population Density And Community Structure Of Birds Breeding In The Kalahari Woodland, Ne Namibia

Fig. 4. Percentage of main nesting guilds in 2014 and 2015.

opencc-by-4.0Dec 2021View details →

Fig. 1 in The Diversity And Species Composition Of Water Beetles (Gyrinidae, Dytiscidae, Hydrophilidae) In A Peat Bog In Belarus

Fig. 1. Study area and the sampling places: L — Lakes, H — Hollows, S — Streams.

Fig. 7 in The Diversity Of Cuculiform And Piciform Species In Partly Transformed Riparian Zambezi Forest

Fig. 7. Distribution of breeding pairs of woodpeckers in Zambezi riparian forest.

Fig. 5 in The Diversity Of Cuculiform And Piciform Species In Partly Transformed Riparian Zambezi Forest

Fig. 5. Distribution of occupied male territories of cuckoos in Zambezi riparian forest.

Fig. 2 in The Diversity Of Cuculiform And Piciform Species In Partly Transformed Riparian Zambezi Forest

Fig. 2. Zambezi forest dominated by Lonchocarpus trees.

Fig. 6 in The Diversity Of Cuculiform And Piciform Species In Partly Transformed Riparian Zambezi Forest

Fig. 6. Distribution of occupied male territories of coucals in Zambezi riparian forest.

opencc-zeroApr 2022View details →

Eco-evolutionary dynamics modulate plant responses to global change depending on plant diversity and species identity

Global change has dramatic impacts on grassland diversity. However, little is known about how fast species can adapt to diversity loss and how this affects their responses to global change. Here, we performed a common garden experiment testing whether plant responses to global change are influenced by their selection history and the conditioning history of soil at different plant diversity levels. Using seeds of four grass species and soil samples from a 14-year-old biodiversity experiment, we grew the offspring of the plants either in their own soil or in soil of a different community, and exposed them either to drought, increased nitrogen input, or a combination of both. Under nitrogen addition, offspring of plants selected at high diversity produced more biomass than those selected at low diversity, while drought neutralized differences in biomass production. Moreover, under the influence of global change drivers, soil history, and to a lesser extent plant history, had species-specific effects on trait expression. Our results show that plant diversity modulates plant-soil interactions and growth strategies of plants, which in turn affects plant eco-evolutionary pathways. How this change affects species' response to global change and whether this can cause a feedback loop should be investigated in more detail in future studies.

opencc-zeroMay 2022View details →

Diversity and predicted function of gut microbes from two species of viviparid snails

Animal gut bacteria are involved in numerous critical functions. In snails, gut bacteria play crucial roles in organic material digestion and nutrient production, and have been implicated in aspects of reproduction. Snail gut microbes are known to differ between species, and between anatomical compartments of the digestive tract; dietary changes are also known to alter snail gut flora. In an effort to better understand their diversity and function, we studied the gut microbial communities from two viviparid snails, Campeloma decisum and Cipangopaludina japonica. We were interested in whether significant differences in bacterial community composition existed between the two species, and whether differences in microbial diversity corresponded to differences in community function. Using next-generation sequencing of the bacterial 16S V4 region, we found no significant differences in alpha and beta diversity between Ca. decisum and Ci. japonica. Firmicutes and Proteobacteria were the most abundant bacterial phyla in both species, while Bacteroidetes had a higher mean abundance in Ci. japonica. Nine taxonomic groups were significantly different between the snail species. Pseudomonads and Enterobacteriaceae were notably more abundant in Ca. decisum, while Proteobacteria and Chitinophagaceae were more abundant in Ci. japonica. Peptidoglycan synthesis, pyruvate fermentation, and aerobic respiration by cytochrome c were the three most abundant microbial pathways represented in the viviparid gut. Fourteen functional pathways differed significantly between Ca. decisum and Ci. japonica, potentially correlated with differences in bacterial community composition and snail life history. Our data fill in data gaps regarding gut microbes in Viviparidae, and highlight future research paths examining the prevalence of Firmicutes and unidentified diversity in both snail species.

opencc-zeroMay 2022View details →

Interactions between soil microbes and native species drive a diversity-invasibility relationship

Soil microbes can affect both the invasiveness of exotic plants and the invasibility of native plant communities, but it still remains unclear whether soil microbes can influence the relationship between native plant species diversity and community invasibility. We constructed native plant communities with three levels of species richness (one, three, or six species) in un-sterilized or sterilized soil (i.e., with or without soil microbes) and let them not be invaded by exotic plant species or invaded by one of three exotic species (Solidago canadensis, Erigeron canadensis or Symphyotrichum subulatum) highly invasive in China. The soils conditioned by the native plant communities not invaded by the exotic species were used as soil microbe inocula to test whether richness-induced differences in soil microbes affect the growth of each of the three invasive species. Compared with the presence of soil microbes, the absence of soil microbes weakened the negative species richness-invasibility relationship, indicating that soil microbes can contribute to the higher invasion resistance of more diverse native plant communities. In the presence of soil microbes, the higher invasion resistance of more diverse communities was mainly ascribed to the complementarity effect. However, soil microbes from communities with a higher species richness did not have a stronger negative effect on the growth of any of the three invasive species. We conclude that soil microbes can alter the diversity-invasibility relationship through promoting the complementarity effect on the community invasion resistance. Our results highlight the importance to integrate the role of soil microbes in testing the diversity-invasibility hypothesis.