Species Pool Research Articles

Different levels of disturbance influence the distributional patterns of native but not exotic plant species on New Zealand small islands

Disturbances of oceanic origin can severely affect plant communities on islands, but it is unclear whether they promote or deter biological invasions. Here, I collected floristic data from 97 small islands subject to different levels of ocean-borne disturbances (i.e. inside and outside Wellington Harbour, New Zealand). First, I tested how relationships between the richness of native and exotic species and island characteristics (e.g. area, isolation, height, distance from nearest dwelling) changed depending on island location. Next, I assessed compositional differences on inner and outer islands for both native and exotic species, and how they vary with geographic distance between islands (i.e. distance-decay). Results show that the richness of both native and exotic plant species was similarly related to island characteristics regardless of island location. Both native and exotic species richness consistently increased with area and nearest dwelling. However, only exotics richness always declined with isolation, while natives richness alone consistently increased with height (elevation). Natives on outer, more exposed islands were floristically more homogenous, and compositional differences changed less strongly with the distance between islands than inside Wellington harbour. In contrast, exotics exhibited similar distributional patterns regardless of island location. Different levels of ocean-borne disturbances might explain distinct distributional patterns in native species. Conversely, results for exotic species might reflect a lack of coastal specialists in the species pool. Perhaps time-lags in the invasion process and non-equilibrium dynamics play a role as well. Conservation bodies should similarly manage islands sustaining different levels of ocean-borne disturbances.

GLACIAL RELICT OF TOMENTHYPNUM NITENS (HEDW.) LOESKE (AMBLYSTEGIACEAE) IN THE UKRAINIAN CARPATHIANS: DISTRIBUTION AND PHYTOCOENOTIC TIMING

We found that within the Ukrainian Carpathians Tomenthypnum nitens is a regionally rare species with a narrow ecological amplitude. The article provides a map of the current distribution of the species within the Ukrainian Carpathians, taking into account new findings. T. nitens was found exclusively on meso- and eutrophic bogs in the communities of three associations of the Scheuchzerio palustris-Caricetea fuscae class: ass. Caricetum davallianae Dutoit 1924, ass. Carici flavae-Eriophoretum latifoliae Soό 1944, which belong to the order Caricetalia davallianae, as well as ass. Caricetum nigrae Braun 1915 of the order Caricetalia nigrae. Its greatest coenotic activity is shown in the ass. Carici flavae-Eriophoretum latifoliae. The detailed characteristics of plant communities with the participation of T. nitens and the idea of its inclusion in the Red List of Transcarpathia in order to preserve the gene pool of relict species of the Carpathians are substantiated. A list of mosses occurring in plant communities together with the Tomenthypnum nitens is given. Among them are Aulacomnium palustre, Helodium blandowii, Calliergonella cuspidata, Campulium stellatum var. protensum, Palustriella commutata, Thuidium delicatulum, Phylonotis fontana, Plagiomnium ellipticum, Climacium dendroides.

Concurrent assessment of functional types in extant vegetation and soil seed banks informs environmental constraints and mechanisms of plant community turnover in temperate forests of south-eastern Australia

Our understanding of how environmental heterogeneity shapes plant community dynamics is largely based on above-ground diversity despite the importance of seed banks as reservoirs of genetic and taxonomic diversity that buffer plant populations and influence vegetation following disturbance. Using a plant functional trait approach, this study examined the importance of fire-related germination cues and environmental determinants of plant community turnover in wet forests of south-eastern Australia – forests of both high conservation value and the focus of current timber harvesting. We surveyed extant vegetation, soil seed banks, forest structure and edaphic properties across 62 sites burnt in 1939 and not subsequently affected by wildfire or logging. A total of 46 families, and 99 species were identified in extant vegetation with 43 and 126 respectively in the soil seed bank, with only 32% of species co-occurring in both species’ pools. Despite historically long fire return intervals, the soil seed bank demonstrated a clear positive response to fire-related germination cues (heat in combination with smoke) that were concentrated in hard-seeded species dispersed by ants. Seeds from early successional species showed no response to fire cues, while species typical of the wetter margins of these forests were killed by high heat. The soil seed bank was dominated by species associated with early successional stages, consistent with the initial floristics model of succession. Woody species were largely restricted to extant vegetation and replacement is most likely to occur from future seed rain. Spatially structured environmental heterogeneity shaped plant turnover with the relative strength of environmental controls differing among functional types and pools of diversity. Differential response of the combined species pool relative to extant vegetation demonstrates that the soil seed bank provides a storage effect. Forest management practices that generate patchy and heterogenous environments, including the intensity of regeneration burns and density of overstorey species, will benefit biodiversity conservation through overstorey structural controls on resource availability and diversity of understorey vegetation, that is transferred to soil seed banks via tight abiotic controls and seed inputs.

Life history adaptations of Carabus populations in a suburban park: A capture-recapture case study

A two seasons capture-recapture study was preformed between 2016 and 2017, focusing on the Carabus species living in a suburban park in Budapest, Hungary. Eighty-four live-capture non-baited pitfall traps were placed in a grid covering an area of 567 m 2 . Five Carabus species were captured in the park from the nine species in the potential species pool. The most numerous were C. scheidleri , C. ulrichii and C. coriaceus . C. convexus and C. intricatus were captured only a few times. All Carabus species were individually marked and released. We experienced high fluctuation in the estimated population size of C. scheidleri and C. ulrichii, the two most abundant species. The marking technique made possible to detect that the two dominant species overwinter both as larvae and as adults, and thus share remarkably similar life histories. Similar habitat preference, life cycle and low dispersal power sets stage for potential competition between the two species. Due to population sizes below viability limit and the potential for competitive interactions, we presume that a larger network of metapopulation structure makes it possible that these populations persist in a suburban park. The results indicate that urban parks, if they are sufficiently connected to other suitable habitat patches, can have a significant importance in preserving large bodied predatory Carabus species.

How drought tolerant are tropical woody crop species – turgor loss points for the five most common species in the emerging landscapes on the Malaysian Peninsular

Drought events are increasing with climate change and threaten the future of industrial plantations in Southeast Asia. Drought tolerance has been well investigated for oil palm plantations. A comparative study on the tolerance of different woody crop species is still missing. We assessed the leaf turgor loss point of five common woody crop species using osmometry. The aim was to assess possible future risks in terms of the species´ drought tolerance. The research was carried out in Simpang Pertang, Malaysia. We collected botanical material from five species, namely Acacia mangium, Hevea brasiliensis, Tectona grandis, Mangifera indica, and Elaeis guineensis. To assess the adaptation of the local tree species pool, we measured the turgor loss point of the 65 most abundant tree species in the Pasoh forest reserve for comparison. Measured species showed a wide range of drought tolerance, ranging from -2.56 MPa to -1.15 MPa and -2.46 MPa to -0.88 MPa for crop species and forest species, respectively. Under the current precipitation regime, there is less concern about the cultivation success of these species in the study area. With the predicted changes in rainfall intensity and frequency, a reduction in the productivity of woody crop plantations can be expected.

Flow variation at multiple scales filters fish life histories and constrains community diversity in desert streams

AbstractEnvironmental regimes, which encompass decadal‐scale or longer variation in climate and disturbance, shape communities by selecting for adaptive life histories, behaviors, and morphologies. In turn, at ecological timescales, extreme events may cause short‐term changes in composition and structure via mortality and recolonization of the species pool. Here, we illustrate how short‐term variation in desert stream fish communities following floods and droughts depends on the context of the long‐term flow regime through ecological filtering of life history strategies. Using quarterly measures of fish populations in streams spanning a 10‐fold gradient in flow variation in Arizona, USA, we quantified temporal change in community composition and life history strategies. In streams with highly variable flow regimes, fish communities were less diverse, fluctuation in species richness was the principle mechanism of temporal change in diversity, and communities were dominated by opportunistic life history strategies. Conversely, relatively stable flow regimes resulted in more diverse communities with greater species replacement and dominance of periodic and equilibrium strategies. Importantly, the effects of anomalous high‐ and low‐flow events depended on flow regime. Under more stable flow regimes, fish diversity was lower following large floods than after seasons without floods, whereas diversity was independent of high‐flow events in streams with flashier flow regimes. Likewise, community life history composition was more dependent on antecedent anomalous events in stable compared to more temporally variable regimes. These findings indicate that extreme events may be a second‐level filter on community composition, with effects contingent on the long‐term properties of the disturbance regime (e.g., overall degree of variation) in which extremes take place. Ongoing changes to global environmental regimes will likely drive new patterns of community response to extreme events.

The nature of dispersal barriers and their impact on regional species pool richness and turnover

AbstractAimWe document realized and potential global species ranges based on empirically vetted species concepts in conjunction with global climate databases and climate suitability modelling. From this we investigate the nature of dispersal barriers and illustrate how they generate ecological uniqueness.LocationHolarctic.MethodsFifty‐two small body‐size (i.e. < 5 mm) land snail taxa within the genera Euconulus, Pupilla and Vertigo were considered. These represent ~10% of all small body‐size Holarctic land snails and are among the most proficient known passive dispersers. Their potential climatic ranges were determined using Maxent modelling based on 9205 occurrence records. From these we inferred the location, width and nature of isolating barriers and tested for their effects on regional species pool richness and turnover.ResultsUse of unvetted traditional taxonomic concepts and unverified occurrence records would have created up to threefold higher or lower estimates of species‐specific climatic tolerances than the actual values. Modelling must thus only use high quality occurrence data. All but one taxon were shown at a global scale to possess multiple isolated areas of appropriate climate. While oceans represented the most common barrier (37%), intra‐continental barriers were in total almost twice as frequent (inappropriate climate – 29%, habitat/history – 27% and the Greenland ice sheet – 7%). These barriers restricted taxa to only a subset of their potential range, with European taxa possessing approximately twice the global occupancy rates as North American ones (median scores of 62 vs. 34%). As a result, regional taxa pools were three times smaller than their potential sizes, with 50% change in composition occurring over ~2600‐km distances.Main conclusionsEven for these readily dispersing taxa, isolation barriers prevented species from saturating their potential global range, reduced the size of regional species pools by 2/3, and generated ecological uniqueness between them.

What Does the Future Hold for Páramo Plants? A Modelling Approach

Understanding the effects of climate change on tropicalpine biota remains a scientific challenge today. The Andean páramo is the largest and most diverse tropicalpine biogeographical region in the world, and also one of the most threatened as it is prone to accelerated environmental changes. My goal was to predict changes in the distribution ranges of the diverse and highly endemic páramo flora on the mid-term (50 years). First, I predicted distribution changes in páramo plant species under novel climates and considering dispersal constraints. Second, I looked for consensus areas of species losses vs. gains in the páramo, expecting to identify a gradient of increasing relative richness with elevation over time. Last, I evaluated the behavior of plant species regarding their climatic refugia since the Last Glacial Maximum (LGM) to establish if they likely remain or transcend them. Based on VegParamo vegetation data and CHELSA bioclimatic information, I performed species distribution models for a 664 species pool, that were then contrasted between the present, future (2070) and past (LGM). About 8.3% of the entire species pool (55 species) were predicted to be extirpated from the páramo by 2070, including 22 species endemics. On average, páramo plants gained 15.52% of additional distribution by 2070 (18.81% for endemics). Models predicted the most area gains for the northern páramos of Colombia and Venezuela, and the highest losses for the eastern Ecuadorian and Peruvian mountains. Moreover, area gains were more pronounced at high elevations, suggesting a future accelerated colonization process toward the northern Andean summits. Finally, only 21.41% of the species’ 2070 distribution coincided with their LGM (19.75% for endemics), and the largest climatic refugia since the LGM were found in southern Ecuador and Peru. This study is pioneer in predicting future distribution shifts for páramo plant species overall and provides solid bases to support climate change research and adaptation strategies in the tropical Andes.

Squirrel and tree‐shrew responses along an urbanisation gradient in a tropical mega‐city – reduced biodiversity, increased hybridisation of Callosciurus squirrels, and effects of habitat quality

AbstractUrbanisation is rapidly transforming terrestrial environments, especially in the tropics. Many squirrel species tolerate urbanisation, but studies are biased towards temperate regions. We quantify the distribution and abundance of squirrels and (ecologically similar) tree‐shrews along an urbanisation gradient in a rapidly urbanising tropical mega‐city (Bangkok, Thailand) located within the Indo‐Burma biodiversity hotspot. We used repeated point counts in 150 1 km cells, selected using random stratification across the urbanisation gradient. We quantified species responses to (i) urbanisation intensity (measured using impervious surface cover), (ii) environmental conditions (woodland quantity and quality, human disturbance and predation pressure from free‐ranging cats and dogs) and (iii) urbanisation impacts on hybridisation between congeneric Callosciurus squirrels. Three of the six species from the regional species pool were extremely rare or absent within our study region (Tamiops macclellandi, Callosciurus caniceps and Menetes berdmorei). Of the three more widespread species (Tupaia belangeri, Callosciurus finlaysonii and Callosciurus erythraeus) only C. finlaysonii had a higher abundance in more urban locations. The increasing intensity of urbanisation has thus markedly reduced squirrel diversity and abundance, contrasting with the perception from temperate regions that squirrels typically tolerate urbanisation. Urbanisation is thus likely to have reduced important ecological functions provided by squirrels, such as seed dispersal. Models of species responses to environmental conditions suggest that improving habitat quality by increasing tree cover and diversity at local and landscape scales and reducing human disturbance and numbers of feral dogs would partially mitigating adverse impacts of urbanisation on tropical squirrels and tree‐shrews. Urban infrastructure (bridge construction across the Chao‐Praya River) appears to have increased the permeability of a geographic barrier that previously separated C. finlaysonii and C. erythraeus distributions, increasing hybridisation rates. Our study enhances understanding of the ecological impacts of urbanisation in biodiverse tropical regions and the action required to mitigate these impacts.

Species Diversity and Community Composition of Macroinvertebrates in Headwater Streams of Two Subtropical Neighboring Lowland Basins

Determining the patterns of diversity and community composition in headwater streams is fundamental to river biodiversity conservation. Environmental selection has been assumed to be a major force driving temperate macroinvertebrate assembly. To test this assumption in the subtropics, we conducted identical surveys for headwater streams in two neighboring basins, which are located on two sides of a north–south mountain in southern China. We sampled macroinvertebrates and measured habitat and environmental variables in headwater streams of the two basins. The two groups of headwater streams share a species pool and have similar taxa, taxa richness, and functional composition. Beta diversity accounted for a high proportion of the within-basin diversity, and was mainly attributed to the replacement differences. Highly similarity between the two basins’ species composition showed similar environmental selection in structuring macroinvertebrate communities at the regional scale. Redundancy analysis showed that basin identity is the key factor explaining the variation of communities. Environmental selection is an important factor in structuring macroinvertebrate communities within individual basins. Annual precipitation differs significantly on the two sides of the mountain shaded by the East Asia monsoon, resulting in distinctive substrate compositions in the two basins. Our study provides empirical support for the roles of environmental selection in shaping subtropical macroinvertebrate communities.

Can vegetation clearing operations and reprofiling of bars be considered as an ecological restoration measure? Lessons from a 10‐year vegetation monitoring program (Loire River, France)

Maintenance operations in regulated rivers are often implemented as preventive measure to maintain wide, smooth channels and to limit the risk of flooding. By clearing vegetation, removing roots and lowering sediment bar elevation, these works can recreate pioneer habitats and related plant communities. Using a before‐after‐control‐impact design with monitoring of riparian vegetation over 10 years, we evaluated the effects of fluvial maintenance works on plant richness and composition in an island complex located in a Nature Reserve along the Middle Loire River. Our results showed that artificial rejuvenation operations had a significant short‐term negative effect on richness. However, in the few years following the work, the riparian communities established on the rejuvenated island became more diverse, with a large proportion of annual plants, contributing to the increased species pool of the Nature Reserve. In addition, we found that temporal changes in species richness were strongly influenced by hydrological conditions, with a peak in biodiversity observed during prolonged summer low water. This highlights the importance of considering flow variations to more accurately assess the ecological benefit of restoration operations on riparian vegetation. Overall, as successional stages were more advanced at the island complex scale, fluvial maintenance works have allowed the recreation of sandy pioneer habitats exposed to flooding. These habitats have promoted the establishment of species‐rich communities without favoring the installation of invasive alien species. From this view, the maintenance works have increased the mosaic of habitats within the Nature Reserve and have restored environmental conditions favorable to early‐successional species.

Spatial and temporal extents of natural disturbances differentiate deadwood-inhabiting fungal communities in spruce primary forest ecosystems

Understanding the processes shaping the composition of assemblages at multiple spatial scales in response to disturbance events is crucial for preventing ongoing biodiversity loss and for improving current forest management policies aimed at mitigating climate change and enhancing forest resilience. Deadwood-inhabiting fungi represent an essential component of forest ecosystems through their association with deadwood decomposition and the cycling of nutrients and carbon. Although we have sufficient evidence for the fundamental role of deadwood availability and variability of decay stages for fungal species diversity, the influence of long-term natural disturbance regimes as the main driver of deadwood quantity and quality has not been sufficiently documented. We used a dendroecological approach to analyse the effect of 250-years of historical natural disturbance and structural habitat elements on local (plot-level) and regional (stand-level) species richness of deadwood-inhabiting fungi. We used data collected from 51 study plots within nine best-preserved primary spruce forest stands distributed across the Western Carpathian Mountains. Historical disturbances shaped the contemporary local and regional species richness of fungi, with contrasting impacts of disturbance regime components at different spatial scales. While local diversity of red-listed species has increased due to higher disturbance frequency, regional diversity of all species has decreased due to higher severity historical disturbances. The volume of deadwood positively influenced the species richness of deadwood-inhabiting fungi while canopy openness had a negative impact. The high number of observed rare species highlights the important role of primary forests for biodiversity conservation. From a landscape perspective, we can conclude that the distribution of species from the regional species pool is - at least to some extent - driven by past spatiotemporal patterns of disturbance events. Natural disturbances occurring at higher frequencies that create a mosaic forest structure are necessary for fungal species - especially for rare and endangered taxa. Thus, both the protection of intact forest landscapes and forest management practises that emulate natural disturbance processes are recommended to support habitats of diverse fungal communities and their associated ecosystem functions.

Who can pass the urban filter? A multi-taxon approach to disentangle pollinator trait–environmental relationships

Cities are considered important refuges for insect pollinators. This has been shown repeatedly for wild bees, but may also be true for other diverse taxa such as hoverflies. However, our understanding of how urban environmental filters shape pollinator species communities and their traits is still limited. Here, we used wild bee and hoverfly species, communities and their functional traits to illustrate how environmental filters on the landscape and local scale shape urban species pools. The multi-taxon approach revealed that environmental filtering predominantly occurred at the landscape scale as urbanisation and 3D connectivity significantly structured the taxonomic and functional composition of wild bee (sociality, nesting, diet, body size) and hoverfly (larval food type, migratory status) communities. We identified urban winners and losers attributed to taxon-specific responses to urban filters. Our results suggest that insect pollinator conservation needs to take place primarily at the landscape level while considering species traits, especially by increasing habitat connectivity.

Middle Devonian brachiopod-hosted sclerobiont assemblage from the northern shelf of Gondwana (Mader Basin, Morocco): Diversity, colonization patterns and relation to coeval palaeocommunities

Middle Devonian (Eifelian/Givetian transition) brachiopod-hosted sclerobiont assemblage from Gondwana (Morocco, eastern Anti-Atlas, Mader Basin) has been studied for the first time. The analysis of hundreds of brachiopod shells revealed at least 26 sclerobiont taxa, making the studied palaeoecommunity one of the most diverse Middle Devonian sclerobiont assemblage reported to date. The palaeocommunity is dominated by encrusting organisms, in particular bryozoans, foraminifers, ascodictyids and microconchids, whereas bioeroders are represented by Clionolithes and Oichnus ichnospecies. As supported by microfacies, fossil preservation and the presence of encrusting Rothpletzella algae, the sclerobionts developed in a calm, euphotic, offshore marine environment situated below normal wave base. Prevalence of articulated shells without signs of either extensive mineral staining, or taphonomic alteration resulting from hydrodynamic processes, as well as preservation of some delicate encrusters ( Vinella , Rothpletzella ), indicate that the palaeocommunity did not undergo extensive time-averaging. The hosts were colonized syn vivo , as evidenced by the epibiont growth near the commissure margin, the presence of shell malformations and even embedded auloporid corals and cornulitid tubeworms. Competition for space among sclerobionts was apparently limited, as suggested by the very low number of overgrowth interactions, indicating that the shelly substrate available for colonization was abundant. The presence of the same dominant groups of sclerobionts on different host taxa indicates a lack of species-selectivity by these colonizing sclerobionts. It also suggests that the sclerobiont species pool in the environment was generally similar throughout the deposition of the sampled rock interval. As testified by the host brachiopod and bryozoan species, the sclerobiont assemblage from this locality of northern Gondwana had strong affinities with those from the southern margin of Laurussia, most likely reflecting strong connectivity between these regions provided by the South Equatorial – North Gondwana current system during the late Eifelian Kačák transgressive episode. • Diverse sclerobionts colonizing Middle Devonian brachiopods from Morocco are reported. • The assemblage is dominated by bryozoans, foraminifers, ascodictyids and microconchids. • The sclerobionts developed in a calm, euphotic, offshore environment below normal wave base. • The sclerobionts had strong affinities with assemblages inhabiting southern margin of Laurussia. • Their dispersion was enhanced during the late Eifelian Kačák transgressive episode.

Macroflora of the Krkonoše-Piedmont Basin (Pennsylvanian–early Permian); Bohemian Massif, Czech Republic

The Krkonoše-Piedmont Basin is one of several land-locked post-collisional Variscan basins of the Bohemian Massif. The fossil record of the basin is evaluated, based on published data and unpublished lists of floras collected in borehole cores and during mapping. The occurrence ranges of plant taxa are plotted against radioisotopically calibrated lithostratigraphic units. The compiled dataset is used to evaluate species richness and vegetation patterns throughout Late Pennsylvanian and Asselian times. The species richness of particular intervals has been affected by taphonomic and sampling biases of varying intensities. Coal-bearing strata and grey lacustrine intervals represent well-documented fossil-rich taphonomic windows with 20–45 species. In contrast, red beds are fossil-poor and under-sampled, typically providing only a few species. It is assumed that coal-bearing and grey lacustrine intervals represent periods of increased climatic humidity, during which wetlands covered extensive areas of basinal lowlands or shallows and coastal areas of meromictic lakes. Most habitats were colonised by hygrophytes and mesophytes. However, sparse conifer shoots found in association with wetland taxa indicate seasonality to a sufficient degree that xerophytic taxa were able to get close to sites of deposition and wetland habitats. During the deposition of red beds, wetlands may have almost completely disappeared, resulting in the basinal landscape being colonised by gymnosperm-dominated forests of walchian conifers with co-dominant cordaitaleans. Wetland assemblages of low diversity and small populations may have survived in the basin, although many species may have disappeared from the basin, having dispersed elsewhere to habitats where their survival was possible. In the late Middle Pennsylvanian and early Upper Pennsylvanian, such habitats existed in the Intra-Sudetic Basin farther east, and in other basins located in western and central parts of the Bohemian Massif. These climatically-driven oscillations in vegetation patterns, which occurred on scales of hundreds of thousands to a million years, were superimposed on a long-term drying trend marked by an increase in gymnosperms in the species pool, as well as an abundance of their remains in the fossil record, at the expense of free-sporing plants. Among the gymnosperms, there was a gradual drop in the diversity and abundance of medullosalean pteridosperms and a concomitant rise of peltasperms and conifers.

Functional and Taxonomic Overlap in Shore Fish Assemblages in a Tropical Seascape

The relationships between shore fish assemblages from habitats neighboring coral reefs have received little attention in the Indo-Pacific. The present study is based on the extensive sampling (539,000 fish; 898 taxa) of three fish assemblages: reefs, mangroves, and soft-bottoms in a large bay of New Caledonia. Species area curves indicate that sampling was nearly exhaustive in all three habitats (262 species in mangroves, 342 on soft-bottoms, 594 on reefs). Combinations of life-history traits were used as proxies of ecological functions. The species and functional overlaps were highest between soft-bottoms and mangroves and lowest between mangroves and reefs. These overlaps were lower than most recent studies in the Indo-Pacific, a result probably linked to the extent of the sampling in the present study. The life-history traits of species found exclusively in one habitat as opposed to several habitats were not a random selection within the species pool. Overlapping species were mostly large species that fed on nekton, large invertebrates, or plankton; exclusive species were mostly sedentary, solitary, and of small size, except for plankton-feeding species, which mostly had large home ranges and formed large schools. Herbivores were seldom found in several habitats. Functional redundancy was correlated to species richness, and was highest in reef fish assemblages. Functions common to several habitats had very seldom the same relative redundancy, implying that these functions had not the same importance for each assemblage. Functions exclusive to one habitat generally had low redundancy. These functional attributes and species overlap suggest that these three assemblages have a low level of interaction, despite the fact that they share extensive boundaries. These findings may have important applications in the management of shore fish assemblages.

Functional redundancy dampens precipitation change impacts on species‐rich invertebrate communities across the Neotropics

Abstract Animal community responses to extreme climate events can be predicted from the functional traits represented within communities. However, it is unclear whether geographic variation in the response of functional community structure to climate change is primarily driven by physiological matching to local conditions (local adaptation hypothesis) or by differences between species pools in functional redundancy (insurance hypothesis). We conducted a coordinated experiment to understand how aquatic invertebrate traits mediate the responses of multitrophic communities to changes in the quantity and evenness of rainfall in 180 natural freshwater microcosms (tank bromeliads) distributed across six sites from 18°N in the Caribbean to 29°S in South America. At each site, we manipulated the mean and dispersion of the daily amount of rainfall that entered tank bromeliads over a 2‐month period. Manipulations covered a response surface representing 50% to 200% of the dispersion of daily rainfall crossed with 10% to 300% of the mean amounts of rainfall. The response of functional community structure to precipitation regimes differed across sites. These geographic differences were not consistent with the local adaptation hypothesis, as responses did not correlate with the current amplitude in precipitation. Geographic differences in community responses were consistent with the insurance hypothesis: sites with the lowest functional redundancy in their species pools had the strongest response to a gradient in hydrological variability induced by uneven precipitation. In such sites, an increase in the hydrologic variability induced a shift from communities with both pelagic and benthic traits using both green and brown energy channels to strictly benthic, brown energy communities. Our results predict uneven impacts of precipitation change on community structure and energy channels within communities across Neotropical regions. This geographic variation is due more to differences in the size and redundancy of species pools than to local adaptation. Strategies for climate change adaptation should thus seek to identify and preserve functionally unique species and their habitats. Read the free Plain Language Summary for this article on the Journal blog.

Where is the forest core area? Gradients of flora in the ecotone of urban forests in Warsaw

Urban forests are very important ecosystems, performing key cultural services and having crucial regulatory functions. However, naturally valuable areas in cities continue to decline or undergo irreversible transformations. It is necessary to determine the extent of human influence on forest ecosystems in highly urbanized environments. Our study examined the indicators of diversity, naturalness, lability, and stability of flora along transects from edge to center of six urban forests. Furthermore, the shape of gradients of changes and the threshold distance and straightness between forest edge and core for these indicators were measured. Finally, the impact of the number of inhabitants, the degree of protection, and the size and shape of the forests on each indicator separately and their aggregation in the form of the Flora Transformation Index were analyzed. The findings revealed that the gradients of changes were rarely linear and showed a logarithmic or polynomial shape. The most regular gradients were observed for lability and naturalness of flora. The regularity of the shape of the thresholds differed between the studied indicators. The threshold distance was relatively far (93–113 m) and depended heavily on human influence, but forest shape and area were also very important. Our results showed that legal protection, even as a reserve, has no effect in the case of solid human penetration of the forest. Our findings are expected to help determine suitable indicators for defining threshold values, i.e., the size of the edge and core zones of urban forests, which is crucial to the protection of the native plant species pool.

Post‐Pleistocene dispersal explains the Rapoport effect in North American salamanders

AbstractAimsIn many taxa, the latitudinal span of species' geographic ranges are positively correlated with median latitude (the Rapoport effect). This correlation is frequently explained as adaptation to contemporary climate; however, variability in post‐glacial range expansion among species could also explain this observation. We analyse geographic data for North American salamanders to test the potential causes of Rapoport effects.LocationTemperate North America.TaxonSalamanders (order Caudata).MethodsWe tested for a Rapoport effect by estimating correlations between the latitudinal midpoint and latitudinal range among species. Next, we manipulated species' latitudinal ranges by removing post‐glacial habitat and assessing the impact of species demonstrating post‐glacial range expansion in forming a Rapoport effect. We built ecological niche models for species found south of the Wisconsin Ice Sheet during the Last Glacial Maximum and transferred these models to post‐glacial areas. If dispersal is important in forming a Rapoport effect, then some species may tolerate northern climates but have not expanded northward as a result of variation in geographic access to post‐glacial habitats. We created binary ecological niche models by thresholding using the equal sensitivity and specificity value.ResultsWe recovered a Rapoport effect that was robust to the null models we tested. Analyses that manipulated ranges and species pools supported a role for variation in post‐glacial range expansion among species, especially for eastern North America. Results from transferring ecological niche models indicated that species have suitable habitat north of their range limit.Main conclusionsVariation in post‐glacial range expansion is important in shaping geographic range size clines among species in areas where climates changed rapidly, though we also found support for the climatic variability hypothesis. Post‐glacial colonization and range expansion likely plays an important role in forming latitudinal biodiversity gradients in northern taxa. While ecophysiology and biotic interactions have been emphasized as important contributors to diversity gradients, our study indicates that post‐glacial colonization also plays a key role in forming latitudinal gradients.

Biogeographic, Driving Factors, Assembly, and Co-occurrence Patterns of Archaeal Community in Biocrusts.

Archaea exhibit strong community heterogeneity with microhabitat gradients and are a non-negligible part of biocrust’s microorganisms. The study on archaeal biogeography in biocrusts could provide new insights for its application in environmental restoration. However, only a few studies on assembly processes and co-occurrence patterns of the archaeal community in patchy biocrusts have been reported, especially considering the number of species pools (SPs). Here, we comprehensively collected biocrusts across 3,500 km of northern China. Different successional biocrusts from various regions contain information of local climate and microenvironments, which can shape multiple unique archaeal SPs. The archaeal community differences in the same successional stage exceeded the variations between successional stages, which was due to the fact that the heterogeneous taxa tended to exchange between unknown patches driven by drift. We also comparatively studied the driving forces of community heterogeneity across three to ten SPs, and assembly and co-occurrence patterns were systematically analyzed. The results revealed that the impact of spatial factors on biogeographic patterns was greater than that of environmental and successional factors and that impact decreased with the number of SPs considered. Meanwhile, community heterogeneity at the phylogenetic facet was more sensitive to these driving factors than the taxonomic facet. Subgroups 1 (SG1) and 2 (SG2) of the archaeal communities in biocrusts were dominated by Nitrososphaeraceae and Haloarchaea, respectively. The former distribution pattern was associated with non-salinity-related variables and primarily assembled by drift, whereas the latter was associated with salinity-related variables and primarily assembled by homogeneous selection. Finally, network analysis indicated that the SG1 network had a higher proportion of competition and key taxa than the SG2 network, but the network of SG2 was more complex. Our study suggested that the development of the archaeal community was not consistent with biocrusts succession. The dominant taxa may determine the patterns of community biogeography, assembly, and co-occurrence.