Distribution Limits Of Species Research Articles

Geologically recent rearrangements in central Amazonian river network and their importance for the riverine barrier hypothesis

The riverine barrier hypothesis is a central concept in Amazonian biogeography. It states that large rivers limit species distributions and trigger vicariant speciation. Although the hypothesis has explanatory power, many recent biogeographical observations addressing it have produced conflicting results. We propose that the controversies arise because tributary arrangements in the Amazon river system have changed in geologically recent times, such that large tracts of forest that were on the same side of a river at one time got separated to different sides at another. Based on topographical data and sediment dating, we map about 20 major avulsion and river capture events that have rearranged the river network in central Amazonia during the late Pleistocene and Holocene. We identify areas where past riverine barrier effects might still linger in the absence of a major river, as well as areas where such effects may not yet have accumulated across an existing river. These results call for a reinterpretation of previous biogeographical studies and a reorientation of future works to take into account the idiosyncratic histories of individual rivers.

Comparative analysis of the distribution and habitats of two <i>Eremias</i> species (Reptilia, Lacertidae) using niche-based GIS modeling

The distribution and habitat characteristics of two Eremias species ( E. arguta and E. stummeri ) from contiguous areas of southeastern Kazakhstan, northeastern Kyrgyzstan, and western Xinjiang, China, were analyzed using GIS modeling. We show that both species are dry-steppe-adapted xerophilous lizards with sclerophilic and partially petrophilic specialization. In spite of the visible similarity of the ecological niches (ENs) occupied by E. arguta and E. stummeri , the latter differs in a number of key variables. While most of the precipitation variables, the radiation of the winter and off-season months, and afternoon (PM) humidity are most important for E. arguta habitats, the habitats suitable for E. stummeri are limited by temperature variables, radiation during most of the year, and morning (AM) humidity. Differences on this scale indicate the way in which these lizards are adapted to different ecosystems — E. arguta to the plains and E. stummeri to the mountains — and support the views on their different zoogeographical accessory. A visible correspondence of the distributional pattern of the two Eremias species to the mountain piedmonts and low foothills, with Pliocene-Quaternary concreted pebble deposits and the loess strata, permit us to consider mountain trails as the most likely means by which the species expanded in the Late Cenozoic period. Pronounced isolation of the populations in the Northern and the Central Tien Shan intra-montane depressions appears as a factor from at least the Late Pliocene ( E. stummeri ) and the Middle Pleistocene ( E. arguta ) periods; and the association of the lizard habitats with loess deposits has given rise to the suggestion that there was an absence of serious change in their ranges during the Last Glacial Maximum (LGM). Low precipitation, a high annual temperature range and the high aridity of the climate in general beyond the ENM optimum of E. arguta all point to severe conditions for lizards surviving already in the eastern part of the Ily Basin and explain the limited species distribution in the highly arid deserts of Xinjiang. In terms of methodology, our data highlights the lack of a ‘generalized set’ of BIOCLIM parameters in the ecological niche modeling of the mountain species. In particular, moisture and solar radiation as well as the relief variables play an important role in the ecological health of the poikilothermic xerophilous species inhabiting mountain areas.

New species of black corals (Cnidaria: Anthozoa: Antipatharia) from the New Zealand region, part 2

ABSTRACT One new genus and ten new species of antipatharian corals are described from the New Zealand region. Differential diagnoses are given and comparisons are made to related nominal species. Described as new is the genus Acanthosaropathes and the following species: Antipathes coronata, A. dicrocrada, A. polyhedra, Acanthosaropathes uniseriata, Phanopathes ctenocrada, Cupressopathes simplex, Stylopathes stenotes, Stauropathes stellata, Telopathes tasmaniensis, and Heteropathes intricata. This research highlights the diversity of deepsea corals for the region, improves knowledge of the distributional limits of species, which in turn can inform assessments of species prevalence for conservation initiatives and management decisions.

Integrating mechanistic and correlative niche models to unravel range-limiting processes in a temperate amphibian.

Insights into the causal mechanisms that limit species distributions are likely to improve our ability to anticipate species range shifts in response to climate change. For species with complex life histories, a mechanistic understanding of how climate affects different lifecycle stages may be crucial for making accurate forecasts. Here, we use mechanistic niche modeling (NicheMapR) to derive "proximate" (mechanistic) variables for tadpole, juvenile, and adult Rana temporaria. We modeled the hydroperiod, and maximum and minimum temperatures of shallow (30cm) ponds, as well as activity windows for juveniles and adults. We then used those ("proximate") variables in correlative ecological niche models (Maxent) to assess their role in limiting the species' current distribution, and to investigate the potential effects of climate change on R. temporaria across Europe. We further compared the results with a model based on commonly used macroclimatic ("distal") layers (i.e., bioclimatic layers from WorldClim). The maximum temperature of the warmest month (a macroclimatic variable) and maximum pond temperatures (a mechanistic variable) were the most important range-limiting factors, and maximum temperature thresholds were consistent with the observed upper thermal limit of R. temporaria tadpoles. We found that range shift forecasts in central Europe are far more pessimistic when using distal macroclimatic variables, compared to projections based on proximate mechanistic variables. However, both approaches predicted extensive decreases in climatic suitability in southern Europe, which harbors a significant fraction of the species' genetic diversity. We show how mechanistic modeling provides ways to depict gridded layers that directly reflect the microenvironments experienced by organisms at continental scales, and to reconstruct those predictors without extrapolation under novel future conditions. Furthermore, incorporating those predictors in correlative ecological niche models can help shed light on range-limiting processes, and can have substantial impacts on predictions of climate-induced range shifts.

A Practical Guide to the Study of Distribution Limits.

Factors that limit the geographic distribution of species are broadly important in ecology and evolutionary biology, and understanding distribution limits is imperative for predicting how species will respond to environmental change. Good data indicate that factors such as dispersal limitation, small effective population size, and isolation are sometimes important. But empirical research highlights no single factor that explains the ubiquity of distribution limits. In this article, we outline a guide to tackling distribution limits that integrates established causes, such as dispersal limitation and spatial environmental heterogeneity, with understudied causes, such as mutational load and genetic or developmental integration of traits limiting niche expansion. We highlight how modeling and quantitative genetic and genomic analyses can provide insight into sources of distribution limits. Our practical guide provides a framework for considering the many factors likely to determine species distributions and how the different approaches can be integrated to predict distribution limits using eco-evolutionary modeling. The framework should also help predict distribution limits of invasive species and of species under climate change.

Interspecific aggression among parapatric and sympatric songbirds on a tropical elevational gradient

Abstract Interspecific competition is hypothesized to be a strong force that sets species range limits and drives parapatric distributions of closely related species on tropical mountains. Yet, experimental evidence that competition drives spatial segregation of closely related species on elevational gradients is rare. To test whether competition limits elevational ranges of tropical songbirds, we conducted reciprocal playback experiments on 2 pairs of species with adjacent but nonoverlapping (parapatric) distributions and 1 pair of sympatric species. We found asymmetric interspecific aggression in one parapatric pair (Pycnonotidae) and a complete absence of interspecific aggression in the other (Zosteropidae). We also found asymmetric interspecies aggression in a pair of sympatric flycatchers (Muscicapidae). Our results indicate that interspecific aggression may set range limits in some cases, but it is not a prerequisite for parapatry. Furthermore, the presence of interspecific aggression between co-occurring relatives suggests that while competition may play a role in limiting species distributions, interspecific aggression alone is not sufficient evidence to assert that competition is the primary driver of parapatric distributions.

Isolation on a remote island: genetic and morphological differentiation of a cosmopolitan odonate.

Although low levels of genetic structure are expected in highly widespread species, geographical and/or ecological factors can limit species distributions and promote population structure and morphological differentiation. In order to determine the effects of geographical isolation on population genetic structure and wing morphology, 281 individuals of the cosmopolitan odonate Pantala flavescens were collected from four continental (Central and South America) and five insular sites (Polynesian islands and the Maldives). COI sequences and eight microsatellite loci were used to characterize genetic diversity and genetic structure between and within locations. Linear and geometric morphometry were used to evaluate differences in the size and shape of wings. Genetic analysis showed a global genetic difference between the continental and insular sites. American locations did not show genetic structure, even in locations separated by a distance of 5000 km. Easter Island showed the lowest values of genetic diversity (mainly mitochondrial diversity) and the highest values of genetic differences compared to other insular and continental sites. Individuals from Easter Island showed smaller forewings, a different abdomen length to thorax length ratio, and a different configuration of anal loop in the hindwings. Thus, the greater isolation, smaller area, and young geological age seem to have determined the genetic and morphological differences in P. flavescens of Easter Island, where selection could promote a loss of migratory behavior and may improve other life history traits, such as reproduction. This work provides new insight into how microevolutionary processes operate in isolated populations of cosmopolitan species.

One millennium of historical freshwater fish occurrence data for Portuguese rivers and streams

The insights that historical evidence of human presence and man-made documents provide are unique. For example, using historical data may be critical to adequately understand the ecological requirements of species. However, historical information about freshwater species distribution remains largely a knowledge gap. In this Data Descriptor, we present the Portuguese Historical Fish Database (PHish–DB), a compilation of 2214 records (557 at the basin scale, 184 at the sub-basin scale and 1473 at the segment scale) resulting from a survey of 194 historical documents. The database was developed using a three-scale approach that maximises the inclusion of information by allowing different degrees of spatial acuity. PHish database contains records of 25 taxonomical groups and covers a time span of one millennium, from the 11th until the 20th century. This database has already proven useful for two scientific studies, and PHish further use will contribute to correctly assess the full range of conditions tolerated by species, by establishing adequate benchmark conditions, and/or to improve existing knowledge of the species distribution limits.

An Inventory of Bryophytes on the Summit of Pink Mountain (Peace River District, British Columbia, Canada)

The bryophyte diversity in northern British Columbia is insufficiently studied. We conducted a bryophyte survey in a 2.2-km2 proposed ecological reserve at the summit of Pink Mountain in the Peace River District of northern British Columbia. Pink Mountain is at the southern periphery of the ranges of several arctic flora species as well as the northernmost reaches of other temperate flora species. The south summit of Pink Mountain has a high floristic diversity coincident with its limestone geology, which provides a more alkaline condition for plant growth than the north summit does. We documented 65 species, including 2 new provincial records for British Columbia (Polytrichum hyperboreum and Tayloria hornschuchii), one red-listed (threatened) species (Tortula systylia), and one blue-listed (at-risk) species (Mnium arizonicum). Polytrichum hyperboreum and T. hornschuchii have affinities to habitats more typical of polar regions. The presence of P. hyperboreum at Pink Mountain represents a southward range extension from 61°33′ N in western North America. Because isolated populations at species distribution limits are likely to be vulnerable to climate change, the establishment of an ecological reserve on the south end of the summit of Pink Mountain is important for the preservation of bryophyte habitat.

Ecological niche differentiation in peripheral populations: a comparative analysis of eleven Mediterranean plant species

The ‘central‐peripheral’ hypothesis has provided a baseline for many studies of population dynamics and genetic variability at species distribution limits. Although peripheral populations are often assumed to occur in ecologically marginal conditions, little is known about whether they effectively occur in a distinct ecological niche. A cross‐taxa analysis of 11 Mediterranean vascular plants were studied.We quantified variation in the ecological niche between populations at the northern range limits of species in Mediterranean France and those in the central part of the distribution in continental Spain or Italy in 2013–2014. We analyzed both the macro‐ecological niche where populations occur in terms of broad habitat and altitudinal range and the micro‐ecological niche where individual plants grow in terms of soil and structural biotic and abiotic characteristics.Most species occur in a single broad habitat type common to central and peripheral populations and have a narrower altitudinal range in the latter. In contrast, for the micro‐ecological niche we detected marked variation in several niche parameters among central and peripheral populations. Although many differences are species‐specific some are common to several species. We found a trend towards narrower micro‐niche breadth in peripheral populations.Our results illustrate the importance of studying the precise ecological characteristics where plants grow and the pertinence of a multi‐species approach to correctly assess niche variation. The ecological originality of peripheral populations underlines their evolutionary potential and conservation significance.

Latitudinal effects on phenology near the northern limit of figs in China

The interaction between pollinating wasps and figs is an obligate plant-insect mutualism, and the ca. 750 Ficus species are mainly tropical. Climatic constraints may limit species distributions through their phenology and this seems particularly likely for figs, where phenological mismatches can cause local extinction of the short-lived pollinators. We therefore compared the phenologies of Ficus altissima, F. racemosa and F. semicordata in tropical Xishuangbanna (21°55′N) and subtropical Liuku (25°50′N), SW China, to understand what factors limit fig distributions near their northern limits. All species produced synchronous crops of syconia in Xishuangbanna but production in Liuku was continuous, which may help maintain pollinator populations. However, in general, we found decreased fitness at the northern site: slower syconium development, so fewer crops each year; fewer seeds per syconium (two species); and fewer pollinators and more non-pollinators per syconium, so less pollen is dispersed. This is most easily explained by colder winters, although low humidities may also contribute, and suggests the northern limit is set by temperature constraints on reproductive phenology. If so, the warming predicted for future decades is expected to enhance the fitness of northern populations of figs and, in the longer term, allow them to shift their range limits northwards.

Environmental and phenotypic heterogeneity of populations at the trailing range-edge of the habitat-forming macroalga Fucus serratus

Empirical work on the dynamics of range limits of species distributions often lack replications of edge populations. We compared the local environment and performance of two groups of geographically peripheral populations of the foundation intertidal alga Fucus serratus L. at its southern range boundary in the NW Iberian Peninsula. Two populations were located on the Western Galician coast in large embayments or rias, and the other two on a Northern open coastal stretch in Lugo province. Sharp differences were detected in the local environment and performance of the two groups of populations. While recruitment was quite consistent throughout the year in rias, it was very limited and variable in Lugo. Furthermore, thalli from rias were severely damaged following their transplantation in Lugo, and poor conditions of local adult plants were detected there in subsequent years. These results suggest a higher vulnerability of Lugo populations under new climate conditions, while western rias, strongly influenced by upwelling events, feasibly act as contemporary refugia for this species. If sustained over time, these refugia may mitigate the retreat of the seaweed’ rear-edge predicted by large spatial scale models.

An annotated checklist of the mammals of Paraguay

As the center of convergence of some of the major bioregions of South America, Paraguay is a biodiverse country of biogeographic importance. Yet despite a long history of natural history research, basic knowledge of its fauna, including mammals, is still lacking. The last updated list of Paraguayan mammals was published in 2002, but increased research efforts since that time have brought about numerous changes in the taxonomy and known distribution of many species. We present an updated and annotated checklist on the mammals of Paraguay through 2016. Only species records based on the assessment of some type of verifiable voucher are included here. Because the Paraguay River has been considered a significant biogeographic boundary, the distribution of each species (east of the river, west of the river, present on both sides) is tabulated as well. We recorded 181 native species of mammals, 30 more than in 2002, belonging to 10 orders, 33 families, and 116 genera. Chiroptera (58) was the most diverse order, followed by Rodentia (56), Carnivora (20) and Didelphimorphia (18). Ctenomys pilarensis, C. paraguayensis y C. dorsalis are known only from Paraguay. The inventory is likely incomplete, as well as our knowledge of species distributional limits. Continued collecting of tissues and vouchers, as well as an examination of museum specimens, is necessary to address numerous unsolved questions concerning distribution, taxonomy, ecology, biogeography, population biology and the effects of anthropogenic modification.

The latitudinal diversity gradient in South American mammals revisited using a regional analysis approach: The importance of climate at extra-tropical latitudes and history towards the tropics.

The latitudinal diversity gradient has been considered a consequence of a shift in the impact of abiotic and biotic factors that limit species distributions from the poles to the equator, thus influencing species richness variation. It has also been considered the outcome of evolutionary processes that vary over geographical space. We used six South American mammal groups to test the association of environmental and evolutionary factors and the ecological structuring of mammal assemblages with spatial variation in taxonomic richness (TR), at a spatial resolution of 110 km x 110 km, at tropical and extra-tropical latitudes. Based on attributes that represent what mammal species do in ecosystems, we estimated ecological diversity (ED) as a mean pairwise ecological distance between all co-occurring taxa. The mean pairwise phylogenetic distance between all co-occurring taxa (AvPD) was used as an estimation of phylogenetic diversity. Geographically Weighted Regression analyses performed separately for each mammal group identified tropical and extra-tropical high R2 areas where environmental and evolutionary factors strongly accounted for richness variation. Temperature was the most important predictor of TR in high R2 areas outside the tropics, as was AvPD within the tropics. The proportion of TR variation accounted for by environment (either independently or combined with AvPD) was higher in tropical areas of high richness and low ecological diversity than in tropical areas of high richness and high ecological diversity. In conclusion, we confirmed a shift in the impact of environmental factors, mainly temperature, that best account for mammal richness variation in extra-tropical regions, whereas phylogenetic diversity best accounts for richness variation within the tropics. Environment in combination with evolutionary history explained the coexistence of a high number of ecologically similar species within the tropics. Consideration of the influence of contemporary environmental variables and evolutionary history is crucial to understanding of the latitudinal diversity gradient.

The European roe deer (Capreolus capreolus L.) at the northern boundary of its range in Eastern Fennoscandia

The dispersal, population dynamics, and ecological features of the European roe deer at the northern limit of species distribution and also their visits, wintering, and breeding outside the range boundary are discussed. A significant increase in the abundance of roe deer in the northern part of the range and their largescale expansion beyond the historical distribution limit have taken place during the past decade. However, their spread in Karelia and Arkhangelsk oblast is strictly limited, depending primarily on snow depth and duration. Hunting the roe deer as a game species in the region is possible only in the south of Pskov oblast, where habitat conditions are most favorable for it.

The power of the transplant: direct assessment of climate change impacts

Understanding the factors that limit species distributions has become increasingly important in the face of rapid climate change. Many approaches have been used to predict responses of species and communities to new environmental challenges, including species distribution modelling, glasshouse and growth cabinet experiments, and small-scale field manipulations, all of which have both advantages and limitations. Here, we review the use of a powerful, direct method to predict how species and communities will respond to the changing climate: the field transplant experiment. We discuss how transplant experiments can elucidate the factors that limit species distributions; disentangle the role of genetic change vs. phenotypic plasticity in species’ responses; and improve understanding of the role of species interactions in driving community change. Several generalisations about potential species’ responses to climate change are emerging from these studies, including the critical role of specific life stages in response to warming trends, the role of natural enemies and new hosts in limiting or promoting adaptive capacity, and the role of niche saturation in conferring community stability at a functional guild level. Transplant experiments have also confirmed likely mechanisms of recent range shifts and highlighted the potential for some modelling exercises to overestimate future range changes. With the prospect that accelerating warming over the next few decades will increase extinction rates and accelerate ecosystem degradation, we urge researchers to utilise this powerful but underused method more widely.

Natural and anthropogenic barriers to climate tracking in river fishes along a mountain–plains transition zone

AbstractAimTo examine how the distributions of fishes in three rivers changed over four decades of rising air temperatures.LocationColorado, USA.MethodsWe used fish sampling over more than four decades in three rivers in Colorado, USA, to examine changes in the upper and lower distribution limits of fishes.ResultsThere was a divergent pattern of range shifts among species. One coldwater fish species showed the expected pattern of retraction at its lower limit and expansion at its upper limit. However, warmwater fishes, on average, did not shift their upper distribution limit.Main conclusionsAll three rivers displayed a strong habitat transition from upstream, high‐gradient reaches to downstream, low‐gradient reaches, suggesting that habitat conditions associated with high channel slope may limit the ability of some fish species to track warming water temperatures. In addition, potential anthropogenic barriers to fish movement occurred near species distribution limits, and these may prevent or delay range shifts in river fishes. The overall pattern of range shifts was consistent across the three rivers, suggesting a coherent influence of species' traits, physiological tolerances and habitat requirements on fish species distributions.

Temperature but not moisture response of germination shows phylogenetic constraints while both interact with seed mass and lifespan

AbstractUnderstanding how plant traits interact with climate to determine plant niches is decisive for predicting climate change impacts. While lifespan and seed size modify the importance of germination timing, germination traits such as base temperature and base water potential directly translate climatic conditions into germination timing, impacting performance in later life stages. Yet we do not know how base temperature, base water potential, seed mass, lifespan and climate are related. We tested the relationships between base temperature and base water potential for germination, seed size and lifespan while controlling for bioclimatic regions. We also quantified the phylogenetic signal in germination traits and seed size using Pagel's λ. We used a worldwide data set of germination responses to temperature and moisture, seed size and lifespan of 240 seed plants from 49 families. Both germination temperature and moisture are negatively related to seed size. Annual plants show a negative relation between seed size and base water potential, whereas perennials display a negative relation between base temperature and seed mass. Pagel's λ highlighted the slow evolution of base temperature for germination, comparable to seed mass while base water potential was revealed to be labile. In the future, base water potential and seed mass can be used when moisture niches of plants are to be predicted. Lifespan, seed size and base temperature should be taken into account when analysing thermal limits of species distributions.

Canopy distribution and survey detectability of a rare old-growth forest lichen

Forest managers in many parts of the world are charged with protecting rare lichen species, including species growing near their range limits. Rare lichens may be particularly vulnerable to effects of climate change, and conserving lichen diversity necessitates understanding factors that limit species distributions. Habitat suitability envelopes for lichens are shifting as the climate changes, but it is unclear whether and how local (e.g., within-tree) lichen species distributions will shift. Conserving lichen biodiversity also requires effective field surveys to detect and monitor rare lichen populations. However, the reliability of rare lichen survey methods currently used across global forest lands is rarely tested. In this study, we quantify the canopy distribution of an epiphytic old-growth forest cyanolichen near its southern range limit and test whether ground surveys reliably detect canopy populations. Near its southern range limit, Lobaria oregana was most abundant in two distinct zones within tree crowns: on branches of large trees in the mid-crown, and on boles of small trees near ground level. The abundance of this species near ground level suggests that lichens may benefit from cooler, wetter microclimates near the equatorial edges of their ranges. Maintaining these microclimate habitats may be a key to long-term viability of rear edge lichen populations. Targeted ground surveys reliably detected L. oregana in litterfall underneath trees where it was abundant in the crowns. However, ground surveys did not reliably detect the lichen underneath trees when it occurred in the crowns in low abundance. Our results suggest that ground surveys are useful for characterizing abundant lichen species, but that canopy surveys (e.g., tree climbing) may be needed to reliably detect lichens when they occur at low abundance.

Wind differentiates reproduction in the non-expansive Black Tern Chlidonias niger and the expansive White-winged Tern Chlidonias leucopterus

Identifying the key factors governing the expansion of a species’ range is difficult because of the multiple interactions of environmental and biological factors. Among the biological factors are breeding parameters, which at the edge of a species’ range may indicate the traits involved in limiting species distribution. To evaluate whether the hatching success of two sympatric species of terns was dependent on weather parameters, a study was carried out in the valley of the River Bug in eastern Poland. During 2007–2010, nine colonies with 113 clutches of White-winged Tern (CHL, an expansive species, new to the region since 1997) and 92 clutches of Black Tern (CHN, a non-expansive species, nesting in stable numbers in this region for many years) were monitored. CHN arrived on average 9 days earlier than CHL. While CHN arrived in east-central Poland earlier and earlier during the 1998–2013 period, no such trend was recorded for CHL. The clutch initiation median in CHL was 8 days later than in CHN. The hatching success of CHL was statistically less than that of CHN (41.6 vs. 69.6%). A general discriminant analysis model showed that successful CHL clutches depended on the maximum daytime wind speed (strong winds can be disastrous for breeding terns), colony identity and clutch initiation date. In the case of CHN, none of these factors had a statistically significant influence on hatching success, although the clutch initiation date was very close to being significant. These results suggest that a species which nested in the same location for a long time in relation to ambient weather conditions has higher hatching success than the one which is in the process of expanding its distribution range.