Geographic Range Of Species Research Articles

New records of Lolliguncula (Lolliguncula) argus Brakoniecki & Roper, 1985 (Myopsida: Loliginidae) in northwestern Mexico

Seven specimens of Lolliguncula (Lolliguncula) argus, were collected in the shrimp fisheries of the Gulf of California and five specimens from the western coast of Baja California Peninsula, deposited in the Santa Barbara Museum of Natural History (USA), are examined and reported. These records expand species geographic distribution range for approximately 950 km and report the maximum size of mantle length 38.8 mm for males and 60.8 mm for females. Morphometric data of the 12 collected specimens are presented, and species funnel organ and statoliths are described.

Structural overshoot of tree growth with climate variability and the global spectrum of drought-induced forest dieback.

Ongoing climate change poses significant threats to plant function and distribution. Increased temperatures and altered precipitation regimes amplify drought frequency and intensity, elevating plant stress and mortality. Large-scale forest mortality events will have far-reaching impacts on carbon and hydrological cycling, biodiversity, and ecosystem services. However, biogeographical theory and global vegetation models poorly represent recent forest die-off patterns. Furthermore, as trees are sessile and long-lived, their responses to climate extremes are substantially dependent on historical factors. We show that periods of favourable climatic and management conditions that facilitate abundant tree growth can lead to structural overshoot of aboveground tree biomass due to a subsequent temporal mismatch between water demand and availability. When environmental favourability declines, increases in water and temperature stress that are protracted, rapid, or both, drive a gradient of tree structural responses that can modify forest self-thinning relationships. Responses ranging from premature leaf senescence and partial canopy dieback to whole-tree mortality reduce canopy leaf area during the stress period and for a lagged recovery window thereafter. Such temporal mismatches of water requirements from availability can occur at local to regional scales throughout a species geographical range. As climate change projections predict large future fluctuations in both wet and dry conditions, we expect forests to become increasingly structurally mismatched to water availability and thus overbuilt during more stressful episodes. By accounting for the historical context of biomass development, our approach can explain previously problematic aspects of large-scale forest mortality, such as why it can occur throughout the range of a species and yet still be locally highly variable, and why some events seem readily attributable to an ongoing drought while others do not. This refined understanding can facilitate better projections of structural overshoot responses, enabling improved prediction of changes in forest distribution and function from regional to global scales.

A new noteworthy record of Phrynops williamsi Rhodin & Mittermeier (Testudines, Chelidae) in Uruguay

The Neotropical turtle Phrynops williamsi (Testudines, Chelidae) is a scarcely studied species distributed in southern Brazil, north-eastern Argentina, Paraguay and Uruguay. We report herein the finding of a juvenile specimen, it measured 40 mm of carapace length and was collected in February 2013 by Tiago Delpino at San Gregorio de Polanco (32°36'S, 55°50'W), Tacuarembo Department, in a streamlet tributary of the Negro River (MNHN 9487. This new record suggests that P. williamsi is widely distributed over the Negro River basin, at the southern boundaries of the species geographic range.

Barrier Displacement on a Neutral Landscape: Toward a Theory of Continental Biogeography.

Macroevolutionary theory posits three processes leading to lineage diversification and the formation of regional biotas: dispersal (species geographic range expansion), speciation (species lineage splitting), and extinction (species lineage termination). The Theory of Island Biogeography (TIB) predicts species richness values using just two of these processes; dispersal and extinction. Yet most species on Earth live on continents or continental shelves, and the dynamics of evolutionary diversification at regional and continental scales are qualitatively different from those that govern the formation of species richness on biogeographic islands. Certain geomorphological processes operating perennially on continental platforms displace barriers to gene flow and organismal dispersal, and affect all three terms of macroevolutionary diversification. For example, uplift of a dissected landscape and river capture both merge and separate portions of adjacent areas, allowing dispersal and larger geographic ranges, vicariant speciation and smaller geographic ranges, and extinction when range sizes are subdivided below a minimum persistence threshold. The TIB also does not predict many biogeographic and phylogenetic patterns widely observed in continentally distributed taxa, including: (i) power function-like species-area relationships; (ii) log-normal distribution of species geographic range sizes, in which most species have restricted ranges (are endemic) and few species have broad ranges (are cosmopolitan); (iii) mid-domain effects with more species toward the geographic center, and more early-branching, species-poor clades toward the geographic periphery; (iv) exponential rates of net diversification with log-linear accumulation of lineages through geological time; and (v) power function-like relationships between species-richness and clade diversity, in which most clades are species-poor and few clades are species-rich. Current theory does not provide a robust mechanistic framework to connect these seemingly disparate patterns. Here we present SEAMLESS (Spatially Explicit Area Model of Landscape Evolution by SimulationS) that generates clade diversification by moving geographic barriers on a continuous, neutral landscape. SEAMLESS is a neutral Landscape Evolution Model (LEM) that treats species and barriers as functionally equivalent with respect to model parameters. SEAMLESS differs from other model-based biogeographic methods (e.g., Lagrange, GeoSSE, BayArea, and BioGeoBEARS) by modeling properties of dispersal barriers rather than areas, and by modeling the evolution of species lineages on a continuous landscape, rather than the evolution of geographic ranges along branches of a phylogeny. SEAMLESS shows how dispersal is required to maintain species richness and avoid clade-wide extinction, demonstrates that ancestral range size does not predict species richness, and provides a unified explanation for the suite of commonly observed biogeographic and phylogenetic patterns listed above. SEAMLESS explains how a simple barrier-displacement mechanism affects lineage diversification under neutral conditions, and is advanced here toward the formulation of a general theory of continental biogeography. [Diversification, extinction, geodispersal, macroevolution, river capture, vicariance.].

Relationship between Behavioral Thermoregulation and Physiological Function in Larval Stream Salamanders

Abstract Relationships between behavioral regulation, environmental temperatures, and physiological tolerance are critical to conservation policy; however, these relationships may not be consistent among sister taxa. A species geographic range is influenced by various factors including physiological tolerance to temperature change. In this study, we investigated the effects of temperature variation on thermal preference and standard metabolic rates (SMR) of two species of larval salamanders, Eurycea cirrigera (Southern Two-Lined Salamander) and Eurycea wilderae (Blue Ridge Two-Lined Salamander). These species share similar life histories, but E. cirrigera is broadly distributed and E. wilderae occupies a smaller range. We measured SMR using volume of oxygen consumption during closed-circuit respirometery trials conducted at 5°C increments between 5°C and 25°C. Standard metabolic rates were influenced by temperature, with a range of temperature-independent SMRs observed at those temperatures above each spe...

Climate and local abundance in freshwater fishes.

Identifying factors regulating variation in numbers of individuals among populations across a species' distribution is a fundamental goal in ecology. A common prediction, often referred to as the abundant-centre hypothesis, suggests that abundance is highest near the centre of a species' range. However, because of the primary focus on the geographical position of a population, this framework provides little insight into the environmental factors regulating local abundance. While range-wide variation in population abundance associated with environmental conditions has been investigated in terrestrial species, the relationship between climate and local abundance in freshwater taxa across species' distributions is not well understood. We used GIS-based temperature and precipitation data to determine the relationships between climatic conditions and range-wide variation in local abundance for 19 species of North American freshwater fishes. Climate predicted a portion of the variation in local abundance among populations for 18 species. In addition, the relationship between climatic conditions and local abundance varied among species, which is expected as lineages partition the environment across geographical space. The influence of local habitat quality on species persistence is well documented; however, our results also indicate the importance of climate in regulating population sizes across a species geographical range, even in aquatic taxa.

Maximum response of loblolly pine plantations to silvicultural management in the southern United States

Pine plantations in the southern US are among the most intensively managed forests in the world and their productivity has tripled over natural pine forests through application of intensive pine plantation establishment and management practices. As we are trying to increase carbon (C) sequestration through further enhancing pine plantation productivity by refinement of silvicultural regimes, whether a maximum productivity or the maximum potential C sequestration exists remains unclear. Our analysis of six long-term field trials indicated that a maximum productivity and a maximum response to silvicultural practices for loblolly pine (Pinus taeda L.) exist across the species geographic range in the southern US. The maximum response was inversely proportional to the base site quality, and silvicultural treatments never increased productivity above that maximum. Further analysis of loblolly pine culture and density studies demonstrated that the effects of planting density and cultural treatment intensity on biomass production strongly interacted with site quality in that lower quality sites responded more to silvicultural intensity than higher quality sites. The results highlight that we can optimize silvicultural prescriptions for specific sites by changing silvicultural intensity depending on the site quality.

Comparative Quantification of Intralocational, Interlocational, and Interspecific Variability in Stag Beetles (Coleoptera: Lucanidae) and the Questions of Phenotypic Plasticity and Species Selection

Stag beetles show a great intraspecific variation. The morphological variation of a species at a single location is a reflection of the species developmental plasticity (DP) and that across locations is a measure for the species adaptive plasticity (AP). Variations of external morphology (developmentally highly variable) and reproductive organ (developmentally highly stable) were studied in each of 514 locations comprising 187 species to determine intralocational, interlocational, and interspecific variability. Dealing with naturally occurring variation, extra attention was paid to the normality of each data set and the validity of partitioning each variation component. With this, the comparative quantification of DP and AP and its presentation as broad-sense heritability were made possible. The results indicate that intraspecific evolution begins with the diversification in genitalia morphology through selection on individual phenotypes as the traditional theory dictates while DP of external morphology sustains the morphological robustness of species. More significantly, there was a highly significant difference in DP of external morphology among species and the interspecific, broad-sense heritability of DP in body and mandible length was very high, indicating that DP is firmly a genetic trait on its own. Furthermore, DP (of body length) influences the species geographic range (GR) more significantly than the species mean or other measures. DP in external morphology and GR being a highly heritable emergent trait and an emergent property, respectively, at the species level, these findings suggest that DP plays a significant role in interspecific evolution through species selection rather than selection on individual phenotypes.

A review of bush dog Speothos venaticus (Lund, 1842) (Carnivora, Canidae) occurrences in Paraná state, subtropical Brazil.

We report six new occurrence records of the bush dog Speothos venaticus, a widely distributed South American carnivore that is threatened with extinction. These records are accompanied by notes on the places where the records were made, such as vegetation type, date and information about the protection of areas. The records, obtained over the last 17 years in Paraná state, southern Brazil, offer an improved understanding of the species geographic range and the threats it faces and can enable better assessments of the conservation status of the species in southern Brazil.

Uncertainty in identifying local extinctions: the distribution of missing data and its effects on biodiversity measures.

Identifying local extinctions is integral to estimating species richness and geographic range changes and informing extinction risk assessments. However, the species occurrence records underpinning these estimates are frequently compromised by a lack of recorded species absences making it impossible to distinguish between local extinction and lack of survey effort—for a rigorously compiled database of European and Asian Galliformes, approximately 40% of half-degree cells contain records from before but not after 1980. We investigate the distribution of these cells, finding differences between the Palaearctic (forests, low mean human influence index (HII), outside protected areas (PAs)) and Indo-Malaya (grassland, high mean HII, outside PAs). Such cells also occur more in less peaceful countries. We show that different interpretations of these cells can lead to large over/under-estimations of species richness and extent of occurrences, potentially misleading prioritization and extinction risk assessment schemes. To avoid mistakes, local extinctions inferred from sightings records need to account for the history of survey effort in a locality.

Tackling intraspecific genetic structure in distribution models better reflects species geographical range.

Genetic diversity provides insight into heterogeneous demographic and adaptive history across organisms’ distribution ranges. For this reason, decomposing single species into genetic units may represent a powerful tool to better understand biogeographical patterns as well as improve predictions of the effects of GCC (global climate change) on biodiversity loss. Using 279 georeferenced Iberian accessions, we used classes of three intraspecific genetic units of the annual plant Arabidopsis thaliana obtained from the genetic analyses of nuclear SNPs (single nucleotide polymorphisms), chloroplast SNPs, and the vernalization requirement for flowering. We used SDM (species distribution models), including climate, vegetation, and soil data, at the whole‐species and genetic‐unit levels. We compared model outputs for present environmental conditions and with a particularly severe GCC scenario. SDM accuracy was high for genetic units with smaller distribution ranges. Kernel density plots identified the environmental variables underpinning potential distribution ranges of genetic units. Combinations of environmental variables accounted for potential distribution ranges of genetic units, which shrank dramatically with GCC at almost all levels. Only two genetic clusters increased their potential distribution ranges with GCC. The application of SDM to intraspecific genetic units provides a detailed picture on the biogeographical patterns of distinct genetic groups based on different genetic criteria. Our approach also allowed us to pinpoint the genetic changes, in terms of genetic background and physiological requirements for flowering, that Iberian A. thaliana may experience with a GCC scenario applying SDM to intraspecific genetic units.

An integrated trait-based framework to predict extinction risk and guide conservation planning in biodiversity hotspots

Determining species extinction risk and its drivers is a major goal for conservation biology. The IUCN Red List is widely used for classifying extinction-risk and prioritizing conservation action. However, this system has been acknowledged as biased and complementary approaches are strongly recommended to achieve more reliable conclusions on conservation priorities. Species traits, often perceived as determinant for resiliency to disturbances, have been used to identify potentially vulnerable species, even when data are scarce (e.g. Data Deficient species). We provide an integrative and cost-effective framework for predicting species extinction-risk using data on 195 anurans from the Brazilian Cerrado. We used IUCN population trend and expert-perceived vulnerability to habitat alteration as response variables, to identify traits associated to increased extinction-risk. We used species traits, threat pressure and geographic range to determine which species and areas should have higher conservation priority. We found the IUCN extinction-risk to be underestimated, as many species categorized as LC or DD are actually sensitive and/or declining. We identified breeding site, habitat and clutch size as predictors of anuran extinction risk. We found that >70% of the biome's anurans have major protection gaps, incurring in high extinction-risk. The southwest and central regions of the biome are the main hotspots for high extinction-risk species and should be prioritized for conservation. Our framework may be particularly valuable to assess extinction-risk and prioritize conservation action regarding less studied taxa and regions with high anthropogenic pressure, but weak government support and scarce funding.

Pollination ecology of <i>Oreocallis grandiflora</i> (Proteaceae) at the northern and southern ends of its geographic range

Geographic variation in pollination ecology is poorly documented, if at all, in many plant-pollinator systems. Great insights could be gained into the abiotic and biotic factors which impact the evolution of floral properties and their potential to lead to speciation by doing so, as both can vary naturally over the geographic range of a plant species. We characterized the pollination ecology of the Andean tree Oreocallis grandiflora (Family: Proteaceae) at the northern and southern ends of its range in Ecuador and Peru in terms of flower morphology, nectar properties, pollinators and plant reproduction. We found significant divergence in the two populations in terms of style length and flower openness, nectar standing crop and secretion rate, and pollinator community. We did not find a significant difference in the length of the pollen presenter or in nectar sucrose concentration by weight (% Brix). The observed divergence in floral traits between the two study populations may be related to a combination of factors, including genetic drift and isolation by distance, distinctive suites of pollinators, or heterospecific pollen competition, which future studies should further investigate. This study demonstrates that pollination ecology can vary substantially across the geographic range of a species, with implications for delimiting species and subspecific taxa.

The reef coral <I>Siderastrea stellata</I> thriving at its range limit: population structure in Arraial do Cabo, southeastern Brazil

Marginal reef sites are typically characterized by a low diversity of coral species; however, they are considered high conservation priorities. Despite their importance, the ecology of edge populations is poorly known. Arraial do Cabo, which is located within an upwelling region, represents the southernmost limit of the reef coral Siderastrea stellata Verrill, 1868, a species endemic to Brazil. The present study characterizes the population structure of S. stellata in Arraial do Cabo in terms of colony size, density, and percentage cover, in relation to the density of other coral species and seawater temperature. When compared to previous studies on S. stellata, populations within the species geographical range, a decrease in the abundance and colony size was expected to be observed in this edge population. However, S. stellata thrives in Arraial do Cabo and population parameters did not seem to decrease toward the species southern range limit. Siderastrea stellata may have found an ecological niche in a marginal area that is not available with the species range, allowing this population to expand in colony size and number. Siderastrea stellata was the most abundant species within the coral community and appears to be resilient to low temperatures. Recruits and small-sized adults of S. stellata were well represented at all sampling sites, but large-size colonies were more frequent in restricted-access areas. Given its unique environmental features, Arraial do Cabo should be regarded as a hotspot for coral conservation and research in the southwestern Atlantic Ocean.

Patchy distribution and varied habitats of Macrozamia lucida cycads explained by constancy in a key environmental variable

Identifying the influence of environmental variables on the spatio-temporal distribution of organisms remains a central goal of ecology. Although environmental limits to the geographic range of species have been investigated, less information is available regarding the influence of environmental variables limiting species to discrete patches within their geographic range. Identifying environmental variables of importance to the species in question is further complicated where the patches appear to be distributed across a variety of outwardly dissimilar habitats. We assessed the influence of environmental variables on the patchy distribution of Macrozamia lucida L.A.S. Johnson (Zamiaceae) cycads endemic to south-east Queensland, Australia. Here we show that patches of M. lucida are consistently associated with elevated moisture, despite the patches being located in contrasting habitats and topographic positions. Our survey results across five field sites demonstrate that both cycad abundance and adult cycad condition (estimated from measures of adult cycad leaf production and reproductive output) are positively correlated with elevated moisture, as measured by mean minimum relative humidity at the plant–soil interface. The historical biogeography of the genus Macrozamia may be intimately linked with the contraction and fragmentation of Australia’s mesic biomes during the Miocene. It is plausible that current distribution pattern of M. lucida, restricted to discrete patches that meet the species’ environmental requirements, reflects a contraction and fragmentation within its range from a more regular historical distribution under more favourable climatic regimes.

Central and rear-edge populations can be equally vulnerable to warming.

Rear (warm) edge populations are often considered more susceptible to warming than central (cool) populations because of the warmer ambient temperatures they experience, but this overlooks the potential for local variation in thermal tolerances. Here we provide conceptual models illustrating how sensitivity to warming is affected throughout a species' geographical range for locally adapted and non-adapted populations. We test these models for a range-contracting seaweed using observations from a marine heatwave and a 12-month experiment, translocating seaweeds among central, present and historic range edge locations. Growth, reproductive development and survivorship display different temperature thresholds among central and rear-edge populations, but share a 2.5 °C anomaly threshold. Range contraction, therefore, reflects variation in local anomalies rather than differences in absolute temperatures. This demonstrates that warming sensitivity can be similar throughout a species geographical range and highlights the importance of incorporating local adaptation and acclimatization into climate change vulnerability assessments.

High Egg Size Variation in African Blue TitsCyanistes caeruleus ultramarinuson the Periphery of Species Range

Abstract. Amount and quality of resources may be variable and generally poor in habitats of marginal avian populations living at the edge of species breeding range. We studied variation in egg traits (length, breadth, volume and shape) in three populations of the African Blue Tit Cyanistes caeruleus ultramarinus inhabiting degraded habitats in highlands of Algerian Saharan Atlas at mean altitudes 1328–1437 m a.s.l. We found high within-clutch repeatability of all the egg traits studied. As theoretically expected in peripheral parts of the species geographic range, there was considerable variation in egg-size traits among the study populations, with eggs being distinctly smaller and more elongated at a site characterised by most human-modified habitat composed of maquis scrubland with rare Pistacia trees. Egg length and shape tended to be affected by the altitude of nest site and by clutch size, but not laying date. We found some effects of egg traits on hatching and fledging success, suggesting that fitne...

Occurrence data may provide unreliable thermal preferences and breadth of species.

Accurate information on the thermal preference and specialization of species is needed to understand and predict species geographical range size and vulnerability to climate change. Here we estimate the position and breadth of species within thermal gradients based on the shape of the response curve of species abundance to temperature. The objective of the study is to compare the measurements of this approach based on abundance data with those of the classical approach using species' occurrence data. The relationship between species' relative abundance and minimum winter temperature of 106 bird species wintering in the Iberian Peninsula is modeled at 100 Km2 resolution with quadratic logistic regressions. From these models we calculated the preferred temperature of species as the temperature at which the abundance is maximized, and the thermal breadth of species as the relative area under the temperature-abundance curve. We also estimated the thermal preferences and breadth of species as the average temperature and temperature range of the UTM cells in which the species are present. The abundance-temperature response curves reveal that birds prefer higher temperatures to overwinter, and are more thermally selective, than is measured by the classical approach. Moreover, response curves detect a higher inter-specific variability in both thermal preferences and thermal breadth of species. As occurrence data gives the same weight to cells with one or many individuals, the average temperature of the cells in which the species is present roughly reflects the average temperature in the region of study and not the environmental preferences of species.

Conflict between biotic and climatic selective pressures acting on an extended phenotype in a subarctic, but not temperate, environment.

Climatic selective pressures are thought to dominate biotic selective pressures at higher latitudes. However, few studies have experimentally tested how these selective pressures differentially act on traits across latitudes because traits can rarely be manipulated independently of the organism in nature. We overcame this challenge by using an extended phenotype-active bird nests-and conducted reciprocal transplant experiments between a subarctic and temperate site, separated by 14° of latitude. At the subarctic site, biotic selective pressures (nest predation) favoured smaller, non-local temperate nests, whereas climatic selective pressures (temperature) favoured larger local nests, particularly at colder temperatures. By contrast, at the temperate site, climatic and biotic selective pressures acted similarly on temperate and subarctic nests. Our results illustrate a functional trade-off in the subarctic between nest morphologies favoured by biotic versus climatic selective pressures, with climate favouring local nest morphologies. At our temperate site, however, allocative trade-offs in the time and effort devoted to nest construction favour smaller, local nests. Our findings illustrate a conflict between biotic and climatic selective pressures at the northern extremes of a species geographical range, and suggest that trade-offs between trait function and trait elaboration act differentially across latitude to create broad geographic variation in traits.

Range extension and first record of Euryzygomatomys spinosus (Rodentia, Echimyidae) in the Brazilian Cerrado

We present herein the first record of Euryzygomatomys spinosus (G. Fischer, 1814) in the Brazilian Cerrado, based on two adult male specimens collected in a “campo limpo” (dry grassland) area at Sempre Vivas National Park, state of Minas Gerais, southeastern Brazil, in June and August 2014. This taxon was previously known only from the Brazilian Pampas, Paraguayan Chaco Humedo and Atlantic Forest of southeastern and southern Brazil, northeastern Argentina and southern Paraguay. Our records increased the species geographic range 250 km northward, into the Cerrado ecoregion.