Terrestrial Taxa Research Articles

A new halisaurine mosasaur (Squamata: Halisaurinae) from Japan: the first record in the western Pacific realm and the first documented insights into binocular vision in mosasaurs

A specimen of a halisaurine mosasaur is reported from Japan for the first time, closing the pre-existing biogeographical gap between the Middle East and the eastern Pacific. Phosphorosaurus ponpetelegans sp. nov., from the lowermost Maastrichtian of Hokkaido, has been assigned to the genus Phosphorosaurus for sharing the following suite of major cranial characters with P. ortliebi, the type species from Belgium: apex of posterodorsal triangular plateau on frontal reaching level of interorbital constriction; frontal lateral border forming a step-like junction between interorbital and preorbital segments of frontal; preorbital segment of frontal sloping anteroventrally; and stapedial meatus parallel-sided in latero-medial view. Potential autapomorphies that distinguish P. ponpetelegans from other members of Halisaurinae include: postorbitofrontal jugal process elongate and stalk-like, projecting laterally; this process distally bearing a ventrally facing depression for jugal articulation; and lateral surangular–articular suture angular rather than round. The long and laterally projecting jugal processes, when combined with a depressed as well as narrow snout, provide compelling evidence for well-developed binocular vision for the new mosasaur, with an estimated binocular field of view (BFoV) of 35°. This value is unusually high for non-ophidian squamates that typically exhibit a BFoV of 10—20°, and is higher than those of other measured mosasaur taxa by at least 5°. Among colubrid snakes, nocturnal species exhibit greater BFoV than diurnal ones in both arboreal and terrestrial taxa. Known also from the Maastrichtian of Hokkaido are fossils of lantern fish (myctophids) and 10-armed cephalopods (coleoids), both of which are typically bioluminescent today. It is hence proposed that the exceptionally large, forward-facing eyes of P. ponpetelegans may well have been a special adaptation for a nocturnal lifestyle, where they hunted small, bioluminescent prey at night while avoiding direct competition with larger, more piscine mosasaurine taxa such as Mosasaurus hobetsuensis that co-existed with P. ponpetelegans.http://zoobank.org/urn:lsid:zoobank.org:pub:3EF73BE7-B3FE-4441-BA5E-29C5D5FCCBC9

Terrestrial fishes: rivers are barriers to gene flow in annual fishes from the African savanna

AbstractAimWe compared the genetic variability and phylogeographical structure of three sympatric clades of annual killifishes (the Nothobranchius furzeri complex, N. orthonotus complex and N. rachovii complex) inhabiting annually desiccating savanna pools. Hypotheses on the mechanisms affecting intraspecific structure and speciation were tested.LocationTemporary pools in Mozambique (Africa).MethodsThe study is based on spatially detailed samples covering the entire range of all three species complexes. A set of 12–13 microsatellites (1638 individuals, 96 populations) and cytochrome b sequences (463 fish, 152 populations) were used as genetic markers. Phylogenetic and population genetic approaches were used to describe the spatial genetic structure and to test the respective roles of river channels and river basins on diversification.ResultsProfound genetic differentiation among populations was evident; some populations located only a few kilometres apart were genetically very distinct, suggesting a significant role of genetic drift and low dispersal ability. Large rivers (Zambezi, Save, Limpopo) formed major barriers to gene flow, with minor differences among the three complexes. Further, the demographic expansion of previously isolated lineages was often limited by the river channel, and rivers were also confirmed as factors affecting speciation events. River basins and elevational gradient had a smaller, but non‐negligible, role in population structuring.Main conclusionsRiver channels are the main barriers to gene flow in Nothobranchius fishes. The study demonstrated low dispersal ability and congruence in the phylogeographical pattern of all three complexes. Cases where Nothobranchius appear to have crossed river channels result from the dynamics of river morphology rather than from rare dispersal events. This conclusion is supported by simultaneous crossing events across lineages. A further division, also consistent among the three complexes, was detected between drier inland and wetter coastal areas. The phylogeographical pattern of Nothobranchius is unique in that it combines features of both aquatic and terrestrial taxa.

The joint evolution of traits and habitat: ontogenetic shifts in leaf morphology and wetland specialization in Lasthenia.

The interplay between functional traits and habitat associations drives species' evolutionary responses to environmental heterogeneity, including processes such as adaptation, ecological speciation, and niche evolution. Seasonal variation is an aspect of the environment that varies across habitats, and could result in adaptive shifts in trait values across the life cycle of a plant. Here, we use phylogenetic comparative methods to evaluate the joint evolution of plant traits and habitat associations in Lasthenia (Asteraceae), a small clade of predominantly annual plants that have differentiated into an ecologically diverse range of habitats, including seasonal ephemeral wetlands known as vernal pools. Our results support the hypothesis that there is a link between the evolution of leaf morphology and the ecohydrological niche in Lasthenia, and, in the formation of aerenchyma (air space), differentiation between vernal pool and terrestrial taxa is fine-tuned to specific stages of plant ontogeny that reflects the evolution of heterophylly. Our findings demonstrate how the relationships between traits and habitat type can vary across the development of an organism, while highlighting a carefully considered comparative approach for examining correlated trait and niche evolution in a recently diversified and ecologically diverse plant clade.

Towards a natural classification and backbone tree for Sordariomycetes

Sordariomycetes is one of the largest classes of Ascomycota and is characterised by perithecial ascomata and inoperculate unitunicate asci. The class includes many important plant pathogens, as well as endophytes, saprobes, epiphytes, and fungicolous, lichenized or lichenicolous taxa. The class includes freshwater, marine and terrestrial taxa and has a worldwide distribution. This paper provides an updated outline of the Sordariomycetes and a backbone tree incorporating asexual and sexual genera in the class. Based on phylogeny and morphology we introduced three subclasses; Diaporthomycetidae, Lulworthiomycetidae and Meliolomycetidae and five orders; Amplistromatales, Annulatascales, Falcocladiales, Jobellisiales and Togniniales. The outline is based on literature to the end of 2014 and the backbone tree published in this paper. Notes for 397 taxa with information, such as new family and genera novelties, novel molecular data published since the Outline of Ascomycota 2009, and new links between sexual and asexual genera and thus synonymies, are provided. The Sordariomycetes now comprises six subclasses, 28 orders, 90 families and 1344 genera. In addition a list of 829 genera with uncertain placement in Sordariomycetes is also provided.

Simplification of Caribbean reef-fish assemblages over decades of coral reef degradation.

Caribbean coral reefs are becoming structurally simpler, largely due to human impacts. The consequences of this trend for reef-associated communities are currently unclear, but expected to be profound. Here, we assess whether changes in fish assemblages have been non-random over several decades of declining reef structure. More specifically, we predicted that species that depend exclusively on coral reef habitat (i.e., habitat specialists) should be at a disadvantage compared to those that use a broader array of habitats (i.e., habitat generalists). Analysing 3727 abundance trends of 161 Caribbean reef-fishes, surveyed between 1980 and 2006, we found that the trends of habitat-generalists and habitat-specialists differed markedly. The abundance of specialists started to decline in the mid-1980s, reaching a low of ~60% of the 1980 baseline by the mid-1990s. Both the average and the variation in abundance of specialists have increased since the early 2000s, although the average is still well below the baseline level of 1980. This modest recovery occurred despite no clear evidence of a regional recovery in coral reef habitat quality in the Caribbean during the 2000s. In contrast, the abundance of generalist fishes remained relatively stable over the same three decades. Few specialist species are fished, thus their population declines are most likely linked to habitat degradation. These results mirror the observed trends of replacement of specialists by generalists, observed in terrestrial taxa across the globe. A significant challenge that arises from our findings is now to investigate if, and how, such community-level changes in fish populations affect ecosystem function.

Spatial structure in ecological communities – a quantitative analysis

The spatial structure of communities has recently gained much attention in ecology. Spatial structure comprises an important element in communities, but the literature lacks a thorough investigation about possible among‐organism or among‐ecosystem differences in the degree of spatial structure. Here, I conducted a quantitative review to determine if the degree of spatial structure varied predictably between the major organism types and ecosystems. Spatial structure was quantified as the relative fraction of community variation explained purely by spatial variables (fraction S/E). I integrated data from 322 variation partition analyses both in a generalized linear model (GLM) and using a boosted regression tree method, and showed that a mean of 11.0% of the variation in community composition was explained purely by spatial variables. Across all taxa, a body size–S/E relationship was positive. In GLM, fraction S/E increased highly significantly with study extent, it was highest among terrestrial taxa and higher in ectotherms than in homoiotherms. Spatial structure was also higher in omnivores than in autotrophs. These results suggest that the degree of spatial structure is jointly driven by extrinsic factors such as study extent and ecosystem type, and intrinsic factors such as body size, thermoregulation and interactions between body size and dispersal mode. These results should be important not only for basic research, but also conservation and bioassessment programs would benefit from the information about the magnitude of spatial variation in nature.SynthesisSpatial processes comprise an important element in most ecological communities, but the degree to which spatial structure varies across organisms or ecosystems is poorly known. Here, a quantitative review of 322 variation partition analyses indicated that spatial component varied predictably across ecological communities – it was driven by study extent and ecosystem type as well as by species traits such as body size and thermoregulation. These results give deep insights into the magnitude of spatial variation in nature and should be highly beneficial for conservation and bioassessment programs that are built on the information about how communities vary in space.

Home-range allometry in coral reef fishes: comparison to other vertebrates, methodological issues and management implications

Body size has been identified as a key driver of home-range area. Despite considerable research into home-range allometry, the relatively high variability in this relationship among taxa means that the mechanisms driving this relationship are still under debate. To date, studies have predominantly focused on terrestrial taxa, and coral reef fishes in particular have received little attention. We quantitatively reviewed studies examining home range in reef fishes, and assessed the interspecific relationship between body mass and home-range area. Body mass and home range are positively related in reef fishes (slopes of 1.15-1.72), with predators having larger home ranges than herbivorous species. This may be attributed to the mobility and lower abundance of predators' food items. Coral reef fishes, and fishes in general, appear to occupy a smaller area per unit mass than terrestrial vertebrates (intercepts of -0.92 to 0.07 versus ≥1.14). This is likely linked to the relative metabolic costs of moving through water compared to air. The small home ranges of reef fishes and their apparent reluctance to cross open areas suggest that reserves aimed at protecting fish species may be more effective if located across whole reefs, even if those reefs are comparatively small, rather than if they cover subsections of contiguous reef, as home ranges in the former are less likely to cross reserve boundaries.

Early Triassic (early Olenekian) life in the interior of East Gondwana: mixed marine–terrestrial biota from the Kockatea Shale, Western Australia

A new terrestrial–marine assemblage from the lower beds of a thin outcrop section of the Kockatea Shale in the northern Perth Basin, Western Australia, contains a range of fossil groups, most of which are rare or poorly known from the Lower Triassic of the region. To date, the collection includes spinose acritarchs, organic-cemented agglutinated foraminifera, lingulids, minute bivalves and gastropods, ammonoids, spinicaudatans, insects, austriocaridid crustaceans, actinopterygians, a temnospondyl-like mandible, plant remains, and spores and pollen. Of these groups, the insects, crustaceans and macroplant remains are recorded for the first time from this unit.Palynomorphs permit correlation to nearby sections where conodonts indicate an early Olenekian (Smithian) age. The locality likely represents the margin of an Early Triassic shallow interior sea with variable estuarine-like water conditions, at the southwestern end of an elongate embayment within the East Gondwana interior rift–sag system preserved along the Western Australian margin. Monospecific spinose acritarch assemblages intertwined with amorphous organic matter may represent phytoplankton blooms that accumulated as mats, and suggest potentially eutrophic surface waters. The assemblage represents a mixure of marine and terrestrial taxa, suggesting variations in water conditions or that fresh/brackish-water and terrestrial organisms were transported from adjacent biotopes. Some of the lower dark shaly beds are dominated by spinicaudatans, likely indicating periods when the depositional water body was ephemeral, isolated, or subjected to other difficult environmental conditions.The biota of the Kockatea Shale is insufficiently known to estimate biotic diversity and relationships of individual taxa to their Permian progenitors and Triassic successors, but provides a glimpse into a coastal-zone from the interior of eastern Gondwana. Specialist collecting is needed to clarify the taxonomy of many groups, and comparisons to other Lower Triassic sites are required to provide insights into the pattern of biotic decline and recovery at the end-Permian crisis.

New dinosaur and crocodylomorph material from the Middle Jurassic (Bathonian) Kilmaluag Formation, Skye, Scotland

Synopsis Archosaur specimens collected from the Kilmaluag Formation (Great Estuarine Group) of Cladach a’Ghlinne, Skye are described. These comprise crocodylomorph material; a pubis and group of osteoderms with an associated tooth; a theropod tooth; and a dinosaur limb bone. The material is regionally important as the Skye assemblage is dominated by aquatic amphibians and amphibious reptiles with terrestrial taxa being comparatively rare. The crocodylomorph pubis is referable to an indeterminate mesoeucrocodylian; the osteoderms and associated tooth to an indeterminate neosuchian. The Kilmaluag Formation has now yielded the only associated and articulated terrestrial/freshwater Middle Jurassic crocodylomorphs from the UK thus far. The theropod tooth is referable to an indeterminate theropod, and provides the first body fossil evidence of a small theropod taxon from the Bathonian of the Hebridean Basin. The dinosaur limb bone is regarded conservatively as an indeterminate dinosaur although it does possess possible theropod affinities.

Methyl mercury and stable isotopes of nitrogen reveal that a terrestrial spider has a diet of emergent aquatic insects.

Terrestrial spiders transfer methyl mercury (MeHg) to terrestrial consumers such as birds, but how spiders become contaminated with MeHg is not well understood. In the present study, the authors used stable isotopes of nitrogen in combination with MeHg to determine the source of MeHg to terrestrial long-jawed orb weaver spiders (Tetragnatha sp). The authors collected spiders and a variety of other aquatic and terrestrial taxa from 10 shallow ponds in north Texas, USA. Based on MeHg concentrations and stable nitrogen isotope ratios, the authors identified distinct aquatic- and terrestrial-based food chains. Long-jawed orb weaver spiders belonged to the aquatic-based food chain, indicating that they are exposed to MeHg through their consumption of emergent aquatic insects. Additionally, the present study suggests that ecologists can use stable isotopes of nitrogen (δ(15) N) in conjunction with MeHg speciation analysis to distinguish between aquatic and terrestrial food chains.

Predictability in species distributions: a global analysis across organisms and ecosystems

AbstractAimWe explored the effects of multiple species traits, spatial extent and ecosystem type on predictability in species distributions.LocationGlobal.MethodsWe assembled over 4900 published AUC (area under the curve of a receiver operating characteristic plot) values from the species distribution modelling literature. Our data covered broad variation in species characteristics such as body size or trophic position for taxa ranging from bacteria to mammals. Data covered ecosystems from freshwater to forests and encompassed geographical areas from the tropics to polar regions. We used generalized linear mixed models and boosted regression trees to analyse the AUC data.ResultsWe found that most AUC values originated from large‐sized terrestrial taxa while studies considering smaller taxa, especially from aquatic ecosystems, were rare. Predictability was highest in autotrophs and in active non‐flying taxa and increased with body size and study extent. There were marginal differences in predictability between ectotherms and endotherms and between taxa originating from different ecosystems.Main conclusionsOur results suggest that predictability in species distributions is related to organismal variables such as body size, dispersal mode and trophic position as well as to study extent. We also identified a gap in species distribution modelling studies for aquatic species and for small taxa.

A NEW GENUS AND SPECIES OF THE FAMILY TRACHYPACHIDAE (COLEOPTERAN, ADEPHAGA) FROM THE UPPER LADINIAN (MIDDLE TRIASSIC) OF MONTE SAN GIORGIO

A new genus and species of fossil Trachypachidae Praedodromeus sangiorgiensis gen. n sp. n. (Coleoptera, Trachypachidae, Eodromeinae), with well developed asymmetrical mandibles, shorter than the head, subrectangular pronotum and slender tibiae, longer than femora, is described from the Kalkschieferzone (uppermost member of the Meride Limestone) of the Swiss side of Monte San Giorgio. Trachypachidae are terrestrial Coleoptera well represented in the Mesozoic fossil record by the extinct family Eodromeinae. Up to now, more than 33 fossil species belonging to 13 genera of Eodromeinae have been described. The new species is part of a collection of fossil insects that includes members of at least six different orders. Based on the ecology of corresponding extant taxa, this insect assemblage provides new insights on the paleoenvironment of Monte San Giorgio area during the Late Ladinian. The assemblage includes terrestrial taxa that support the presence of emerged land and taxa with long-lasting aquatic larval stage (as Plecoptera and Ephemeroptera) that confirm the presence of stable fresh water basins.

Comparative phylogeography of codistributed aquatic insects in western North America: insights into dispersal and regional patterns of genetic structure

Summary Phylogeographic studies provide insights about complex systems at different evolutionary scales. In addition to providing evidence about ecological processes at the organismal level, a synthesis of studies across taxa can illuminate broad phylogeographic patterns at the landscape scale. We compared the phylogeographic patterns of two codistributed species of aquatic insects, Pteronarcella badia (Plecoptera: Pteronarcyidae) and Drunella grandis (Ephemeroptera: Ephemerellidae), across much of their range in western North America. We conducted population genetic analyses of P. badia and D. grandis individuals that co‐occurred in 22 western North American localities. Patterns of genetic structure and gene flow were compared to test for differential dispersal ability and to determine whether broad‐scale phylogeographic trends are consistent with patterns seen in terrestrial taxa across a similar geographic area. We also evaluated whether patterns observed in these species fit previously proposed models of genetic structure in aquatic organisms. Pteronarcella badia showed greater genetic structure and lower rates of dispersal than D. grandis. Both taxa showed several shared geographic regions of genetic isolation, including the Bitterroot Valley in Montana, the Pacific Northwest, the southern Rocky Mountains and the Colorado Plateau. These broad‐scale phylogeographic patterns are largely consistent with trends observed in several terrestrial taxa across the sample area. D. grandis showed patterns of gene flow consistent with an isolation‐by‐distance model of genetic structure. Patterns observed in P. badia reflect elements of multiple models and may highlight the value of the dendritic network approach to understanding genetic patterns of aquatic taxa at broad geographic scales.

Input of terrestrial invertebrates to streams during monsoon-related flash floods in the southwestern United States

Annual monsoons produce violent thunderstorms in the southwestern USA and can result in significant overland flow and flash floods in stream channels, washing many invertebrates into the streams. We identified >140 taxa of terrestrial invertebrates in samples collected from receding flows in ephemeral stream channels after monsoon-related flash floods at 14 sites in Arizona and New Mexico. Relative to the number of aquatic organisms, proportions of terrestrial individuals and terrestrial taxa were initially high but decreased over time. The initial flush of water during the flows appeared to be very destructive, such that the average organism was 40% intact 24 h after waters began to recede. On the second day, the average individual was 90% intact, but the proportion of intact organisms declined over time. These results suggest high inputs of terrestrial invertebrates to these stream ecosystems during the monsoon.

Habitat structure and body size distributions: cross‐ecosystem comparison for taxa with determinate and indeterminate growth

Habitat structure across multiple spatial and temporal scales has been proposed as a key driver of body size distributions for associated communities. Thus, understanding the relationship between habitat and body size is fundamental to developing predictions regarding the influence of habitat change on animal communities. Much of the work assessing the relationship between habitat structure and body size distributions has focused on terrestrial taxa with determinate growth, and has primarily analysed discontinuities (gaps) in the distribution of species mean sizes (species size relationships or SSRs). The suitability of this approach for taxa with indeterminate growth has yet to be determined. We provide a cross‐ecosystem comparison of bird (determinate growth) and fish (indeterminate growth) body mass distributions using four independent data sets. We evaluate three size distribution indices: SSRs, species size–density relationships (SSDRs) and individual size–density relationships (ISDRs), and two types of analysis: looking for either discontinuities or abundance patterns and multi‐modality in the distributions. To assess the respective suitability of these three indices and two analytical approaches for understanding habitat–size relationships in different ecosystems, we compare their ability to differentiate bird or fish communities found within contrasting habitat conditions. All three indices of body size distribution are useful for examining the relationship between cross‐scale patterns of habitat structure and size for species with determinate growth, such as birds. In contrast, for species with indeterminate growth such as fish, the relationship between habitat structure and body size may be masked when using mean summary metrics, and thus individual‐level data (ISDRs) are more useful. Furthermore, ISDRs, which have traditionally been used to study aquatic systems, present a potentially useful common currency for comparing body size distributions across terrestrial and aquatic ecosystems.

Differences in dispersal- and colonization-related traits between taxa from the freshwater and the terrestrial realm

The aquatic and terrestrial realms differ in many physical properties that not only require specific physiological adaptations but also cause differences in dispersal options. We thus expect that life-history traits related to dispersal and colonization are under selection pressure because freshwater habitats are more isolated and thus more difficult to reach. We compared traits from European databases of three taxonomic groups along the passive–active dispersal gradient: plants (Plantes), snails (Mollusca: Gastropoda: Prosobranchia et Pulmonata) and hoverflies (Diptera: Syrphidae), all of which have both terrestrial and freshwater species (plants and snails) or early life stages (hoverflies). Aquatic taxa seem to be more successful long-distance dispersers than are terrestrial taxa. Our analysis also revealed lower numbers of seeds or eggs produced in the aquatic habitats. However, aquatic taxa often allocate resources to offspring guarding (vegetative propagules in plants, egg capsules in snails) and breeding-site selection (syrphids). Colonization of the aquatic realm is reinforced by increases in life span (plants), clonal spread (plants), shorter generation times (snails), selfing ability (marginal effect in pulmonate snails) or paedogenesis (two incidences in hoverflies, needs further studies). Probably, the variety of strategies reflects the different evolutionary backgrounds that elicit different combinations of trade-offs, but all traits also might increase invasibility of species.

Speciation of two stingrays with antitropical distributions: low levels of divergence in mitochondrial DNA and morphological characters suggest recent evolution

Disjunct geographic distributions across the equator (antitropicality) occur in many marine and terrestrial taxa. However, their origin and role in forming new species is still poorly understood. Here we examine the phylogenetic relationships and levels of genetic and morpho- logical divergence in 2 stingray species, the Southern Hemisphere Dasyatis brevicaudata and the Northern Hemisphere D. matsubarai, with antitropical distributions and suspected conserved morphological traits. Analyses of concatenated mtDNA sequences (3160 bp dataset: CO1, cytochrome b, control region) suggest D. brevicaudata and D. matsubarai are closely related sister lineages, with low levels of sequence divergence more akin to intra- rather than interspecific com- parisons. Multivariate analyses of morphological traits are largely consistent with the genetic data in showing small but discrete differences in morphometric characteristics, allowing Northern and Southern Hemisphere individuals to be separated into 2 groups. We suggest that D. brevicaudata and D. matsubarai are closely related sister taxa that may represent an early stage in the process of allopatric speciation.

Investigating the Signature of Aquatic Resource Use within Pleistocene Hominin Dietary Adaptations

There is general agreement that the diet of early hominins underwent dramatic changes shortly after the appearance of stone tools in the archaeological record. It is often assumed that this change is associated with dietary expansion to incorporate large mammal resources. Although other aspects of the hominin diet, such as aquatic or vegetal resources, are assumed to be a part of hominin subsistence, identifying evidence of these adaptations has proved difficult. Here we present a series of analyses that provide methodological support for the inclusion of aquatic resources in hominin dietary reconstructions. We suggest that bone surface modifications in aquatic species are morphologically distinguishable from bone surface modifications on terrestrial taxa. We relate these findings to differences that we document in the surface mechanical properties of the two types of bone, as reflected by significant differences in bone surface microhardness values between aquatic and terrestrial species. We hypothesize that the characteristics of bone surface modifications on aquatic taxa inhibit the ability of zooarchaeologists to consistently diagnose them correctly. Contingently, this difficulty influences correspondence levels between zooarchaeologists, and may therefore result in misinterpretation of the taphonomic history of early Pleistocene aquatic faunal assemblages. A blind test using aquatic specimens and a select group of 9 experienced zooarchaeologists as participants was designed to test this hypothesis. Investigation of 4 different possible explanations for blind test results suggest the dominant factors explaining patterning relate to (1) the specific methodologies employed to diagnose modifications on aquatic specimens and (2) the relative experience of participants with modifications on aquatic bone surfaces. Consequently we argue that an important component of early hominin diets may have hitherto been overlooked as a result of (a) the paucity of referential frameworks within which to identify such a component and (b) the inability of applied identification methodologies to consistently do so.

Species turnover and geographic distance in an urban river network

AbstractAimUnderstanding the relationships between species turnover, environmental features and the geographic distance between sites can provide important insights into the processes driving species diversity. This is particularly relevant where the effective distance between sites may be a function of the habitat or topographic features of the landscape and the means of dispersal of the organism. River networks, in particular in human‐modified landscapes, are a striking example of such a situation. Here, we use data for both aquatic and terrestrial organisms across an urban river network to examine patterns of species turnover and to determine whether these patterns differ between different taxonomic groups.LocationSheffield area, UK.MethodsAquatic (macroinvertebrates, diatoms) and terrestrial (birds, plants, butterflies) organisms were surveyed at 41 sites across an urban river network. We assessed the relationship between turnover and three alternative geographic distance measures (Euclidean, network and flow distance), whilst also taking into account the environmental distance between sites, using Mantel and partial Mantel tests.ResultsTurnover of all taxonomic groups apart from butterflies was significantly correlated with at least one measure of geographic distance. The aquatic taxonomic groups showed the strongest correlations with the geographic distance measures, and in particular with network distance. Terrestrial taxa were more closely associated with environmental than any of the geographic distance measures, although network distance remained significant for birds and some plant groups after removing the effect of environmental distance. Water‐dispersed and neophyte plant groups were significantly related to network and flow distance.Main conclusionsThe results suggest that aquatic communities are strongly influenced by spatial processes occurring within the river network. Terrestrial taxa have a more complex relationship with distance, with different components of these communities displaying different responses. Nevertheless, it is clear that connectivity along the river corridor is important for both aquatic and terrestrial communities.

Ecophysiological forecasting for environmental change adaptation

Ecophysiological forecasting for environmental change adaptation