Homogenization Of Fauna Research Articles

Butterfly loss in urban landscapes and nature reserves

ContextUrbanization and landscape homogenization are main drivers causing biodiversity loss across the globe. The transformation of natural and semi-natural habitats into agro-environments and settlement areas causes the reduction of species diversity, and thus faunal homogenization. ObjectiveIn this study, we analyse changes in land-cover and habitat configuration and test for changes in species richness and community composition of butterflies in an urban area and a nature reserve. MethodWe analysed historical and recent aerial and satellite pictures, and studied the butterfly fauna for two areas in northern Austria, the urban area around Salzburg city and the nature reserve Bluntautal in close geographic proximity. For these analyses we consider the period 1946–2018. ResultsThe proportion of settlement area and forest increased in average by about 5%. Size of field copses increased and small-scale connectivity and thus landscape complexity decreased in both areas. In the same time span, we found a decrease in butterfly species richness for both areas, and in the nature reserve Bluntautal particularly for the past two decades by 50%. The species community composition changed significantly, with severe losses of specialist and xerothermophilic species which rely on open and extensively used ecosystems. ConclusionsThe findings underpin that the reduction of landscape complexity and the intensification of land-use including urbanization drives the loss of diversity of butterflies and changes in species composition, today dominated by some few generalist species. This trend is particularly observable for the nature reserve Bluntautal, where a large proportion of species diversity has disappeared in recent years despite nature conservation. This case underlines habitat management in nature reserves is needed to hold a high level of habitat quality and to preserve the entire species diversity.

A Morrison stem gekkotan reveals gecko evolution and Jurassic biogeography.

Geckos are a speciose and globally distributed clade of Squamata (lizards, including snakes and amphisbaenians) that are characterized by a host of modifications for nocturnal, scansorial and insectivorous ecologies. They are among the oldest divergences in the lizard crown, so understanding the origin of geckoes (Gekkota) is essential to understanding the origin of Squamata, the most species-rich extant tetrapod clade. However, the poor fossil record of gekkotans has obscured the sequence and timing of the assembly of their distinctive morphology. Here, we describe the first North American stem gekkotan based on a three-dimensionally preserved skull from the Morrison Formation of western North America. Despite its Late Jurassic age, the new species already possesses several key characteristics of the gekkotan skull along with retained ancestral features. We show that this new stem gekkotan, and several previously named species of uncertain phylogenetic relationships, comprise a widespread clade of early crown lizards, substantiating faunal homogeneity in Laurasia during the Late Jurassic that extended across disparate ecological, body-size and physiological classes.

Pocillopora damicornis-associated macroinvertebrate responses to spatial gradients in the southern Mexican Pacific

We explicitly tested for spatial changes in Pocillopora damicornis-associated invertebrates across several spatial scales in the southern Mexican Pacific. Sorting of invertebrates from 40 coral heads along 882 km of the coast yielded 325 taxa, 283% more than any other Pocillopora spp. coral host study to date, but estimators signals that richness might be 17–39% larger than the current number. Permutation, ordination, and regression analysis indicate that the composition and abundance of invertebrates vary in response to the spatial distance among coral heads: high similarity and variation occur among coral heads within localities (<500 m), probably related to faunal homogenization, but progressively modest reduction in similarity and variation as spatial distance increases suggesting a weak role for environmental sorting across southern Mexican Pacific coral reefs. Future studies should explicitly explore spatial, environmental, and historical biogeography processes that regulate and maintain community structure and biodiversity on eastern Pacific reefs.

Landscape homogenisation and simplified butterfly community structure go on par across Northern Austria

ContextAgricultural intensification has led to strong homogenization of landscapes. Field copses have become larger, the boundaries between habitats became sharper, and land plots have been cultivated more intensively. In parallel, most field copses, ruderal areas and hedgerows were removed. As a result, ecotones and rarely used microhabitats largely disappeared. In consequence, many suitable habitats for species such as butterflies vanished and the permeability of the landscape decreased, with negative effects on biodiversity.ObjectiveIn this study we analyse land-use and habitat configuration, and butterfly diversity for the years 1953 and 2018 for northern Austria.MethodsWe assessed land cover and landscape configuration for the years 1953 and 2018 on a field-by-field basis across northern Austria, based on aerial and satellite images. We studied butterfly diversity for these two identical periods of time.ResultsOur data show a decrease of the number of field copses over the past decades and a reduction in landscape complexity. The expected number of butterflies per sample unit of an assumed species decreased significantly. Particularly sedentary specialists decreased, while the proportion of mobile generalists increased.ConclusionsOur study underlines the general trend of landscape and faunal homogenization, which specifically leads to the vanishing of extensively used micro-habitats and the loss of sedentary specialist species.

Synchronous long‐term trends in abundance and compositional variability of butterflies in Central Europe

AbstractAnnual insect abundances are determined by short‐term population fluctuations and long‐term trends in community composition. Any assessment of this temporal variability needs long‐term quantitative data on abundances. Here we use museum data (1940–2017) of butterflies and burnet moths from southwestern Germany and central Austria comprising 220,758 records from 155 species, and 55,641 records from 170 species, respectively. We ask whether population fluctuations and long‐term population trends are spatially synchronized across larger spatial distances (&gt;300 km) according to the Moran effect, and whether common trends in community composition and stability exist? Population fluctuations of 85.5% of species jointly occurring in both study regions were positively correlated (mean r = 0.30 ± 0.03). Comparing different time windows, we found different sets of species being in spatial synchrony reflecting temporal changes in butterfly community composition. Mesophilic, habitat generalist, and dispersive species were significantly more synchronized than xerothermophilic, habitat specialist, and sedentary species. Long‐distance travelers were particularly synchronized. In both study regions, species rank orders became less even with time. Stability in community composition increased with time with an ongoing trend to faunal homogenization, but not to species loss. Our study points to global and not to local drivers behind trends in butterfly population fluctuations and compositional stability, in the present case to altered land use and urbanization as major drivers toward synchrony and homogenization. Finally, our data have implications for conservation strategies as they strongly indicate that natural landscape structures are associated with higher faunal compositional variability in comparison to agricultural and urban landscapes.

Introduction of non‐native fish for aquaculture in China: A systematic review

AbstractAquaculture, especially of non‐native species and translocated domestic species, is a greatly encouraged way of relieving the conflicts between food and economic demand and resource depletion. We herein summarized the introduction history of non‐native fish for aquacultural use in China, including 105 species introduced from abroad and 61 species translocated domestically across river basins, which has brought great economic benefits but high ecological risks. Of these, one‐fourth have successfully established wild populations in natural waters and 15% have successfully invaded. We presented specific examples of seven aquaculture species/taxa and three aquarium species/taxa to explain their outcomes. The notable economic benefits, complex species composition and strain selection of tilapias, carps and sturgeons may together facilitate their invasion, and result in fish diversity decline, genetic pollution, and loss of ecosystem service. We specifically reviewed invasion cases in lakes and reservoirs and found that lakes in western China and reservoirs made by major hydroprojects are hotspots for non‐native species, and this has led to the disappearance of endemic species and changes to the original faunal composition. The escaped non‐native fish introduced via aquaculture has changed the original fish biogeography, resulting in the loss of assemblage uniqueness and causing faunal homogeneity. China has achieved significant progress in completing the Aichi Targets by improving the legal system and strengthening conservational actions on controlling non‐native species. Further actions, especially on risk assessment and management of non‐native species are expected for a healthy outlook for the aquaculture industry of China.

Low-head dams induce biotic homogenization/differentiation of fish assemblages in subtropical streams.

Extensive distribution of widespread species and the loss of native species driven by anthropogenic disturbances modify community similarity, resulting in a decrease or increase in community distinctiveness. Data from four basins in the Wannan Mountains, China, were used to evaluate the effects of low‐head dams on patterns of fish faunal homogenization and differentiation based on abundance data. We aimed to examine the spatial changes in taxonomic and functional similarities of fish assemblages driven by low‐head dams and to examine whether the changes in the similarity of fish assemblages differed between taxonomic and functional components. We found that low‐head dams significantly decreased the mean taxonomic similarity but increased the mean functional similarity of fish assemblages in impoundments using abundance‐based approaches, suggesting that taxonomic differentiation accompanied functional homogenization in stream fish assemblages. These results show the importance of population abundance in structuring fish faunal homogenization and differentiation at small scales, especially when the major differences among assemblages are in species abundance ranks rather than species identities. Additionally, we also found only a weak positive correlation between changes in mean taxonomic and functional similarities, and partial pairs exhibited considerable variation in patterns of fish faunal homogenization and differentiation for taxonomic and functional components. In conclusion, this study highlighted that the observed taxonomic differentiation of current fish assemblages (short‐term phenomenon) is probably an early warning sign of further homogenization in regions where native species are completely predominated and that changes in taxonomic similarity cannot be used to predict changes in functional similarity.

Dam Construction Impacts Fish Biodiversity in a Subtropical River Network, China

Dams and diversions are a primary threat to freshwater fish biodiversity, including the loss of species and restructuring of communities, often resulting in taxonomic homogenization (increased similarity) over time. Mitigating these impacts requires a strong scientific understanding of both patterns and drivers of fish diversity. Here, we test whether different components of fish biodiversity have changed in response to major dam construction, and whether these patterns are predictable as a function of key environmental factors in the Gan River Basin, China. The results showed that total and native species alpha diversity have declined from the historical period (pre-dam) to the current period (post-dam). A total of 29 native species are lost, while 6 alien species were gained over time. We found evidence for fish faunal homogenization in the Gan River Basin, with a slight (1%) increase in taxonomic similarity among river basins from the historical period to the current period. Additionally, we revealed significant associations between drainage length, drainage area, and average air temperature, and alpha and beta fish diversity. This study provides new insight into the patterns and drivers of fish biodiversity change in the broader Yangtze River Basin and helps inform management efforts seeking to slow, and even reverse, current trajectories of biodiversity change.

Freshwater fish faunas from two Permian rift valleys of Zambia, novel additions to the ichthyofauna of southern Pangea

Toward the end of the Paleozoic, Earth's land masses formed the supercontinent Pangea. Despite the relative lack of large-scale physical dispersal barriers, patterns of endemism and regionalization existed, likely driven by climate. During the later Permian the fossiliferous southern region of Pangea has proven to be remarkably homogeneous in terms of terrestrial floras and faunas. However, these signals among vertebrates are best documented amongst tetrapods, and little attention has been paid to freshwater fish assemblages often occurring in the same rocks. Given the increasingly arid and landlocked conditions of the interior of Pangea, the study of freshwater vertebrate communities can help contribute to an understanding of biogeographic patterns across the supercontinent. Here we report two Permian fish assemblages from the Madumabisa Mudstone Formation of Zambia consisting of actinopterygians and large-bodied elasmobranchs: 1) a middle Permian assemblage from the Mid-Zambezi Basin; and 2) a late Permian assemblage from the Luangwa Basin. These assemblages are compared with other middle and late Permian freshwater ichthyofaunas from Australia, Brazil, Chile and South Africa and found to reinforce signals of faunal homogeneity for terrestrial assemblages found using the richer and more well-documented tetrapod fossil record.

Ichthyological Differentiation and Homogenization in the Pánuco Basin, Mexico

Species introductions and extirpations are key aspects of aquatic ecosystem change that need to be examined at large geographic and temporal scales. The Pánuco Basin (Eastern Mexico) has high ichthyological diversity and ecological heterogeneity. However, freshwater fish (FWF) introductions and extirpations since the mid-1900s have modified species range and distribution. We examine changes in FWF species composition in and among four sub-basins of the Pánuco by comparing fish collection records pre-1980 to 2018. Currently, the FWF of the Pánuco includes 95 species. Fishes in the Poeciliidae, Cyprinidae, and Cichlidae, respectively, comprised most records over time. Significant differences in species composition were found between the first (pre-1980) and last (2011–2018) study periods, but not for periods in-between. Eight independent species groups were key for explaining changes in Pánuco river ichthyofauna; one group was dominated by invasive species, and saw increases in the number of records across study periods (faunal homogenization). Another group was formed by species with conservation concern with a declining number of records over time. Thirteen (2 native and 11 non-native) species were responsible for temporal turnover. These results strongly suggest high rates of differentiation over time (via native species loss) following widespread non-native species introductions.

First footprints occurrence from the Muschelkalk detritical unit of the Catalan Basin: 3D analyses and palaeoichnological implications

Fossil vertebrate footprints are known from several Triassic localities of the Iberian Peninsula. Geological setting and palaeoichnological analyses are presented from the first recovered tetrapod footprints from the Middle Muschelkalk facies of the Iberian Peninsula. The studied outcrop is 40 km NW from Barcelona, in the Catalan Coastal Ranges (Catalan Basin, NE Iberian Peninsula). The stratigraphic section is ascribed to Middle Muschelkalk facies from Late Anisian-Early Ladinian age (Middle Triassic), and comprises mainly red mudstones with interbedded sandstones. Tetrapod footprints are located at the upper part of decametric medium-grain size sandstone intercalated in metric-submetric mudstone beds sequence. The general palaeoenvironment is a floodplain with episodic torrential events. Several 3D models from footprints were made by photogrammetry technique, being useful in the morphological description and depth analyses as indicator of the trackmaker’s pressure weight distribution and locomotion-substrate interaction. Tetrapod footprints are preserved in convex hyporelief in a sandstone bed with ripple laminations, mud-cracks and invertebrate traces. Substrate under the sand was muddy and soft, with progressive desiccation. There are eight footprints from different specimens and trackmakers. Seven of them are attributed to Isochirotherium isp. And Chirotherium isp. In special, three of them clearly resemble to pentadactyl morphology of chirotheriid pes. Potential trackmakers are crurotarsians. The last footprint is isolated and is referable to Rhynchosauroides isp. Potential trackmakers is a lacertoid-type reptile. The finding partially confirms the presence of homogeneous fauna diversity in the Middle Triassic of Europe Dominated by the same ichnofamilies reported here

Landscape-scale drivers of fish faunal homogenization and differentiation in the eastern United States

Establishment of nonnative fishes and extirpations of native fishes have homogenized freshwater fish faunas, yet our understanding of the drivers of this process remain limited. We addressed this knowledge gap by testing three hypotheses about introductions and homogenization of fish communities is the eastern United States: First, whether nonnative fish introductions have caused fish faunas to become homogenized or differentiated; second, whether patterns of faunal change are related to native species richness, propagule pressure, and anthropogenic disturbance; third, whether invasion patterns are attributable to either biotic resistance or preadaptation. We compared taxonomic similarity among watersheds in historical and contemporary time steps, and modeled contributions of different drivers to faunal change within watersheds. Average similarity among watersheds nearly doubled in contemporary times, pointing to substantial fish faunal homogenization. No watersheds lost species; patterns of homogenization are attributable entirely to nonnative species invasion. Community change and nonnative richness were positively associated with agriculture-urban land use, recreational fishing demand, and elevation. Native richness negatively affected community change and nonnative richness. Nonnative species originated from watersheds with higher richness than the ones they invaded, suggesting a role for biotic resistance. Understanding how mechanisms operate across spatial scales will help guide future conservation efforts.

Scale-dependent patterns of fish faunal homogenization in Neotropical reservoirs

The conservation challenges facing freshwater ecosystems necessitate broadening our science from understanding individual species loss to anticipating multi-faceted changes to biodiversity. In recent decades, the process of biotic homogenization by which regional biotas become more similar through time has attracted considerable attention. Here, we (1) quantified spatial and temporal changes in taxonomic and functional similarity of fish assemblages among Neotropical reservoirs, (2) determined nonnative species contributions to changes in taxonomic and functional composition, and (3) evaluated relationships between the changes in taxonomic and functional similarity among reservoirs. We did so by considering different spatial scales: inter- and intra-ecoregions. At inter-ecoregion scale, reservoir fish assemblages have become taxonomically homogenized over time, whereas functional trait composition has tended to differentiate. At intra-ecoregion scale, we detected both taxonomic and functional differentiation over time. Despite these overall trends, different ecoregions exhibited considerable variation in patterns of fish faunal homogenization and differentiation. We found a moderate positive relationship between changes in mean taxonomic and functional similarity among reservoirs at inter-ecoregion scale, which was no longer evident within ecoregions. In conclusion, this study demonstrates the strong scale-dependence of perceived patterns in homogenization, and further highlights the magnitude of threats to freshwater biodiversity in the Neotropical ecosystems.

Sucesión estacional de zooplancton gelatinoso (medusae y ctenophores) del puerto de Mar del Plata, Argentina (Océano Atlántico sudoccidental)

Temporal variation of the population dynamics of the medusae and ctenophores (gelatinous zooplankton) is described over an annual cycle in the Mar del Plata Harbor, Argentina. A total of 18 species were identified, 3 of which were ctenophores (2 of Class Tentaculata and 1 of Nuda) and 15 medusae (14 of Class Hydrozoa and 1 of Scyphozoa). A species of hydromedusae, Annatiara affinis , was observed for the first time in the Argentine Sea. In both groups, species richness and abundances showed the lowest values in the cold period (austral autumn-winter) and the highest values in the warm period (spring-summer). The meroplanktonic medusae Obelia sp. and Eucheilota ventricularis as well as the holoplanktonic Liriope tetraphylla represented 94.2% of the total abundances of this group (classified as dominant). In the ctenophores, the dominant species were Pleurobrachia pileus and Mnemiopsis leidyi , which accounted for 99.3% of the ctenophores. Monthly medusae succession indicated that holoplanktonic species were dominant over practically all the annual cycle in terms of abundance, while considering species richness values, meroplanktonic species showed highest values. Ctenophores (considering abundance values) was displayed alternating periods of approximately three months of dominance between P. pileus and M. leidyi . The Bray-Curtis similarity index performed on medusae identified two groups of seasons with faunal affinity, the 1) cold and 2) warm periods, with the water temperature and non-gelatinous zooplankton abundances as the environmental factors that best explained this variability (BIO-ENV analysis), while for ctenophores, temporal faunal homogeneity was observed and a single group with faunal affinity was identified. https://doi.org/10.25260/EA.19.29.3.0.880

The Invasion Hierarchy: Ecological and Evolutionary Consequences of Invasions in the Fossil Record

Species invasions are pervasive in Earth history, yet the ecological and evolutionary consequences vary greatly. Ancient invasion events can be organized in a hierarchy of increasing invasion intensity from ephemeral invasions to globally pervasive invasive regimes. Each level exhibits emergent properties exceeding the sum of interactions at lower levels. Hierarchy levels correspond to, but do not always exactly correlate with, geographic extent of invasion success. The ecological impacts of lower-level impacts can be negligible or result in temporary community accommodation. Invasion events at moderate to high levels of the hierarchy permanently alter ecological communities, regional faunas, and global ecosystems. The prevalence of invasive species results in evolutionary changes by fostering niche evolution, differential survival of ecologically generalized taxa, faunal homogenization, and suppressing speciation. These impacts can contribute to mass extinctions and biodiversity crises that alter the trajectory of ecological and evolutionary patterns of life. The fossil record provides a long-term record of how invasion impacts may scale up through time, which can augment ecological studies of modern species invasions.

Inter-annual Arcellinida (testate lobose amoebae) assemblage dynamics within lacustrine environments

Arcellinida (testate lobose amoebae) were examined from 22 surface-sediment samples collected from homogenous environments in eastern Canadian lakes (Lac du Castor Blanc, SW Quebec; Oromocto Lake, SW New Brunswick) to: 1) evaluate the faunal consistency of assemblages within the targeted environments; and, 2) assess the Arcellinida assemblage response evident in samples collected from Oromocto Lake in 2010 CE (n = 10) and 2012 CE (n = 6) to inter-annual changes in environmental conditions. Cluster analysis and detrended correspondence analysis (DCA), redundancy analysis (RDA), and Bray-Curtis Dissimilarity Matrix (BCDM) were used to identify the dominant arcellinidan assemblages, determine physicochemical controls over the Arcellinida distribution, and assess the assemblages’ faunal homogeneity, respectively. Cluster analysis, DCA, and BCDM results revealed two distinct and relatively homogenous arcellinidan assemblages: 1) Lac du Castor Blanc Assemblage; and 2) Oromocto Lake Assemblage, which could further be subdivided into Oromocto Lake 2010 CE (OL10), and 2012 CE (OL12) sub-assemblages. RDA results showed that 65.6% of the variance in the arcellinidan distribution could be attributed to four significant parameters; sand size fraction (32.1%), calcium (29.2%), manganese (2.7%), and organic content (1.5%). The OL10 and OL12 sub-assemblages aligned well with the respective sample collection dates of 2010 CE and 2012 CE, with proportions of the healthy-lake-indicating Diffluggiid taxa being higher in OL12, likely due to a concurrent slight increase in substrate organic content in the 2012 CE sediments. Our results confirm the faunal homogeneity of assemblages in limnologically similar environments, and demonstrate the rapid response of Arcellinida assemblages to changes in lake conditions at inter-annual time scales.

Rodent community responses to vegetation and landscape changes in early successional stages of tropical dry forest

The extent to which the array of land covers dominating anthropogenic landscapes impacts on biodiversity remains today an open question of great relevance. The characteristics of the animal communities inhabiting tropical forest early successional stages can determine, to a large extent, the course of secondary succession and natural regeneration. In this study, we evaluated the response of terrestrial rodents to variations in vegetation and landscape attributes, in early stages of tropical dry forest succession, at three integration levels: (1) communities, (2) populations, and (3) individuals. Our results reveal a rodent response to the variation in vegetation and landscape attributes, which indeed was largely modulated by seasonality, and determined by the focal spatial scale considered. In general, most of the species were favored by vegetation structure simplification and increase in understory density, probably due to the increase in refuge and trophic resources. Nevertheless, one species, Lyomis pictus, was sensitive to variation in vegetation composition and negatively affected by a reduction in vegetation structural complexity, which could be explained by the high number of tree seeds included in their diet. We found a higher diversity of rodents in sites surrounded by a high coverage and connectivity of dry and riparian forest, probably because large forest patches act as sources of species and the forest connectivity favors the colonization process toward sites under regeneration. Our results showed that preserving remnants of the original vegetation and implementing management actions at different spatial scales in anthropogenic landscapes is critical for preventing: (1) an increase in generalist populations, (2) rapid faunal homogenization, (3) defaunation, and (4) the loss of specialist species; with profound implications for the ecology of forest, ecosystem services and human health.

Biodiversity of ostracod communities (Crustacea, Ostracoda) in a tropical floodplain

Neotropical floodplains harbour both floating and rooted plants and are associated with rich ostracod communities. After dry seasons, flooding causes recruitment in 2 ways: floods bring in allochthonous macrophytes with associated pleuston communities, and these rising water levels rehydrate plants and attached (ostracod) eggs that dried at the onset of the dry season. We analysed the ostracods communities in the Araguaia River floodplain (Brazil) during 2 hydrological periods (dry and rainy) and evaluated the species distribution in relation to abiotic and biotic factors. We compared the ostracod fauna of 6 lakes in the dry and rainy period and 17 lakes in the rainy period. We tested the hypothesis that the highest values of ostracod community attributes (richness, density, and evenness) occur in the rainy season owing to the influx of allochthonous individuals and the rehydration of the dried autochthonous macrophytes. We indeed observed the highest richness and diversity of ostracods in the rainy season; the homogenizing effect of the flood pulse at the onset of the rainy season caused a more homogeneous fauna (lower beta diversity) during that hydrological period. The distribution of species showed a significant effect of both abiotic factors (local) and hydrological period (regional).

Species invasions threaten the antiquity of China's freshwater fish fauna

AbstractAimHuman‐mediated species introductions and extirpations have resulted in the homogenization of biotas over time. However, there remains considerable uncertainty in our understanding of homogenization process for megadiverse regions of the world. Here, we investigate the consequences of widespread species invasions and extirpations for the biogeography of China's unique freshwater fish fauna.LocationChina.MethodsBy assembling a comprehensive dataset for distribution of Chinese freshwater fishes, we quantify how non‐native fish species, from both overseas introductions and domestic translocations, has led to taxonomic homogenization of fish faunas at watershed, basin, ecoregion and country scales. We explore how the observed patterns in homogenization vary geographically, and identify those species most responsible for the faunal changes. Lastly, we simulate how China's fish fauna may continue to homogenize according to different scenarios of anticipated species introductions and extirpations.ResultsWe demonstrate that species introductions and extirpations have homogenized freshwater fish faunas across China. Overall compositional similarity of watersheds increased by 7.0% (from a historical 14.9% to 21.9% in the present day; Sørensen index). Compositional similarity of 96 of 103 (93.2%) watersheds increased, with western basins exhibiting the highest magnitude. Translocated non‐native species associated with aquaculture practices contributed the most to faunal homogenization when compared to alien species (7.3% and 0.4%, respectively). Furthermore, faunal homogenization is predicted to intensify an additional 0.5–4.2% with increasing numbers of new non‐native species introductions and the extirpation of native species.Main conclusionsSpecies introductions and extirpations have resulted in the significant impoverishment, and thus the loss of antiquity, of China's freshwater fish fauna over the past century. In the light of the growing realization that species composition (not richness) defines the role that biodiversity plays in maintaining ecosystem function, our study highlights the need for conservation strategies in China that consider changing patterns of β diversity.

Development of an Index of Biotic Integrity for the Sand Hills Ecoregion of the Southeastern United States

AbstractWe developed an index of biotic integrity (IBI) for the Sand Hills ecoregion within the upper Coastal Plain of the southeastern United States. This ecoregion exhibits differences in species composition among river basins and possesses a relatively depauperate fish fauna that has been affected by faunal homogenization. We also investigated whether this IBI could be improved by adding benthic macroinvertebrate information. Data collected from 70 wadeable stream sites were used to calculate 45 fish assemblage metrics. Twelve metrics within the categories of species richness, species composition, habitat guild, trophic guild, tolerance level, alien/invasive species, and individual fish condition were retained after screening all metrics for sensitivity to disturbance, redundancy, and ecological content. Heterogeneity of species composition among basins led to a greater reliance on richness, indicator species, trophic guild, and habitat guild metrics rather than on more geographically variable species composition metrics. Characteristic headwater assemblages provided the basis for some metrics, and invader species metrics were included to address faunal homogenization. The Sand Hills IBI (SHIBI) was more accurate ecoregion‐wide than IBIs that were developed for portions of the Sand Hills, correctly classifying about 60% of the disturbed sites compared with less than 30% for the other IBIs. However, the SHIBI was not highly responsive to gradients in site quality, as indicated by an R2 of 0.30 between SHIBI scores and instream habitat quality scores. This R2 value was improved to 0.49 by supplementing the SHIBI with a benthic macroinvertebrate index (the Ephemeroptera, Plecoptera, and Trichoptera index). We conclude that ecoregion‐wide IBIs should (1) be based on ecoregion‐wide data that characterize responses to disturbance and natural habitat gradients, (2) maintain a substantial ecological basis by including several metric classes, and (3) include metrics that address faunal homogenization where disturbance has increased the dispersion of nonnative species and native generalist species. In addition, combining information from different assemblages can enhance IBI responsiveness to disturbance and improve performance.Received May 5, 2016; accepted September 19, 2016 Published online December 8, 2016