洲际入侵植物生态位稳定性研究进展

人类活动引起的大规模洲际物种交换与生物入侵, 改变了当地生态系统结构与功能, 使生物多样性受到日益严重的威胁。本文通过综合分析主要国家和地区入侵植物的地理起源, 发现洲际入侵主要包括东亚—北美、东亚—南美、欧洲—南非、欧洲—北美、欧洲—东亚、北美—大洋洲等, 这些洲际入侵造成的后果往往比陆内入侵更为严重。利用物种分布模型(SDMs)预测入侵物种潜在分布范围是有效管理和提早预防生物入侵的重要依据, 但这些模型的一个关键假定是: 入侵物种的生态位在空间和时间上是保守的、稳定的。然而, 对于远离原产地种群并能快速适应新生境的洲际入侵植物来说, 生态位可能发生显著的变化。入侵种能否在入侵地保持原有的生态位, 取决于制约其生态分布的限制因素和生态过程在不同地区间是否发生变化。本文中作者总结了洲际入侵与陆内入侵的生态与进化过程的异同点, 认为这些限制物种原产地分布的因素如扩散限制、种间互作、适应性进化、生态可塑性和种群遗传特性等均可能导致入侵物种生态位的改变。建议下一步的研究应该重视: (1)对生态位属性进行多尺度的研究, 包括时间、空间、环境或系统发育等几个方面; (2)对比生态位稳定与发生偏移的物种特性, 确定什么样的入侵物种更容易改变原有的生态位; (3)进行生态位时间动态格局研究, 探讨生态位变化的倾向、历史速率和偏移程度, 以便判定生态位变化趋势。这些研究结果将会进一步提高物种分布模型的预测能力, 有助于更为准确地揭示气候变化和物种入侵对生物多样性的影响。     

Niche dynamics in space and time

Niche conservatism, the tendency of a species niche to remain unchanged over time, is often assumed when discussing, explaining or predicting biogeographical patterns. Unfortunately, there has been no basis for predicting niche dynamics over relevant timescales, from tens to a few hundreds of years. The recent application of species distribution models (SDMs) and phylogenetic methods to analysis of niche characteristics has provided insight to niche dynamics. Niche shifts and conservatism have both occurred within the last 100 years, with recent speciation events, and deep within clades of species. There is increasing evidence that coordinated application of these methods can help to identify species which likely fulfill one key assumption in the predictive application of SDMs: an unchanging niche. This will improve confidence in SDM-based predictions of the impacts of climate change and species invasions on species distributions and biodiversity.     

Combining phylogenetic and ecological niche modeling approaches to determine distribution and historical biogeography of Black Hills mountain snails (Oreohelicidae)

We aim to show how a combination of molecular systematics and ecological niche modelling approaches can be used to test historical biogeographical hypotheses for species of conservation concern. We focus on the land snail genus Oreohelix (Oreohelicidae), a group found throughout the Rocky Mountains. In addition to its larger distribution, a group of Oreohelix is also found in the Black Hills of Wyoming and South Dakota, an isolated, easternmost extension of the Rocky Mountains. We determine the number, distribution, and relationships of Black Hills Oreohelicids, which are a current conservation concern due to their fragmented distribution. We compared Black Hills groups to those in the main part of the Rockies to test historical biogeographical patterns that explain current diversity. We collected mtDNA data (COI and 12S sequences) from multiple populations of Oreohelix throughout the Black Hills and in adjacent populations in the Rocky Mountains to construct phylogenetic hypotheses. To determine whether favourable environmental conditions currently exist between the Black Hills and the north-eastern Rocky Mountains, we used DesktopGARP to generate an ecological niche model for distinct lineages discovered in the molecular phylogenetic analysis. Results show that all Black Hills populations are likely Oreohelix cooperi and that little genetic differentiation exists within this clade. In addition, Black Hills groups are genetically similar or identical to populations found in the Judith Mountains and Bighorn Mountains (north-eastern Rockies). Ecological niche models show that suitable environmental conditions may exist between eastern Rockies and Black Hills O. cooperi samples. Taken together, the phylogenetic and niche model data, along with the low vagility of the snails, support passive long-distance dispersal as a likely explanation for current arrangement of biodiversity.     

The use of geostatistics and GIS for evolutionary history studies: the case of the nose‐horned viper (Vipera ammodytes) in the Balkan Peninsula

Geostatistics and geographical information system (GIS) procedures are novel techniques helpful for the identification of environmental correlates sustaining contact zones among subspecies or closely related species. In this paper, we tried to infer evolutionary scenarios for Vipera ammodytes across the European part of its distribution area using geostatistics and ecological niche‐based models, hence trying to solve several biogeographical questions that remained unclear after the application of classical morphological tools and genetic analyses. Eleven morphological traits from 871 vipers were analysed with geostatistics and ecological niche‐based modelling. Interpolation by kriging was used to generate surfaces of morphological variation, which were combined with spatial principal components analysis (SPCA). SPCA maps were used to test putative morphological differentiated groups with discriminant function analysis (DFA). Maximum entropy modelling and seven environmental variables were used to identify factors limiting the distribution of groups and areas for the potential occurrence of such groups. Three patterns of morphological variation were observed: a north‐west/south‐west cline, transition zones with steep clines of variation in a west–east arc, and particular character traits that disturbed the general cline. SPCA identified between three and nine putative population groups, of which three were supported by DFA. Areas of potential occurrence of these groups were coherent with the range of the three subspecies of V. ammodytes currently recognized. The distribution of all subspecies was mostly related to precipitation in the driest month. Areas of probable sympatry between subspecies are generally small and restricted. The main patterns of geographic variation of morphological characters for V. ammodytes were similar to the patterns obtained for Vipera latastei and Vipera monticola; the same environmental factors limit the distribution of differentiated groups of vipers in the Balkans and the Iberian Peninsula. The influence of humidity on the variation of morphological traits in spatially separated viper taxa from the two European peninsulas coincides with their phylogenetic relatedness. Geostatistics and GIS procedures were successful in the identification of environmental correlates sustaining contact zones among V. ammodytes subspecies in the Balkans. The same techniques should be applied for studying other parapatric forms and refugia regions. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 651–666.     

Niche breadth,environmental landscape,and physical barriers: their importance as determinants of species distributions

Species distributions and their patterns in geographical space have been studied for several decades and explained by theories such as Janzen's, with respect to the nature of dispersal barriers in the Tropics, and Rapoport's, with respect to range size. However, the roles of specific environmental and geographical factors (e.g. ecological niche breadth, geographical barriers, etc.) in shaping species ranges and distributional patterns remain largely unexplored. The present study analyzed predictions from these two theories via analysis of virtual species with respect to biogeographical patterns: virtual species were created across South America, covering all major environments on the continent, and were used to compare effects of niche breadth, environmental availability, connectivity, seasonality, and the presence of known biogeographical barriers (rivers) in shaping species distributions and biodiversity patterns. Geographical ranges varied from narrow to broad, depending on the location of the seed point when comparing species produced with the same niche breadth. Analysis without consideration of seasonality and barriers produced species with broader distributions in the Tropics and narrower distributions in montane and temperate regions of the continent. When seasonality was included, however, broader ranges were concentrated in temperate regions, thus supporting Janzen's idea. Rapoport's rule of broader geographical ranges at higher latitudes was supported only when seasonality and physical barriers were included but not in species with very narrow or very broad niches, suggesting that this ‘rule’ results from interactions among niche breadth, dispersal capabilities, and dispersal barriers. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 108 , 241–250.     

How species longevity, intraspecific morphological variation, and geographic range size are related: a comparison using late Cambrian trilobites

Phenotypic variation is fundamental to evolutionary change. Variation not only evinces the connectivity of populations but it is also associated with the adaptability and evolvability of taxa. Despite the potential importance of morphological variation in structuring evolutionary patterns, little is known about how relative differences in intraspecific morphological variation and its geographic structure are linked to differences in species longevity. This study offers a novel combination of analyses that reveal the quantitative relationships among intraspecific variation, geographic range size and duration in the fossil record using late Cambrian trilobites. Results show that geographic range size and duration are positively correlated. Surprisingly, longer lived species tend to have less intraspecific variation. Phylogenetic effects were also explored and found not to determine the association between these variables. However, the distribution of geographic range sizes shows strong phylogenetic signal. In light of previous work, one possible explanation for these results is that species with shorter durations have comparatively higher rates of morphological evolution, reflected in higher phenotypic variation overall.     

Phylogeny, divergence times and species limits of spiny lizards (Sceloporus magister species group) in western North American deserts and Baja California

The broad distribution of the Sceloporus magister species group (squamata: phrynosomatidae) throughout western North America provides an appropriate model for testing biogeographical hypotheses explaining the timing and origins of diversity across mainland deserts and the Baja California Peninsula. We inferred concordant phylogenetic trees describing the higher-level relationships within the magister group using 1.6 kb of mitochondrial DNA (mtDNA) and 1.7 kb of nuclear DNA data. These data provide strong support for the parallel divergence of lineages endemic to the Baja California Peninsula (S. zosteromus and the orcutti complex) in the form of two sequential divergence events at the base of the magister group phylogeny. A relaxed phylogenetic analysis of the mtDNA data using one fossil and one biogeographical constraint provides a chronology of these divergence events and evidence that further diversification within the Baja California clades occurred simultaneously, although patterns of geographical variation and speciation between clades differ. We resolved four major phylogeographical clades within S. magister that (i) provide a novel phylogenetic placement of the Chihuahuan Desert populations sister to the Mojave Desert; (ii) illustrate a mixed history for the Colorado Plateau that includes Mojave and Sonoran Desert components; and (iii) identify an area of overlap between the Mojave and Sonoran Desert clades near Yuma, Arizona. Estimates of bidirectional migration rates among populations of S. magister using four nuclear loci support strong asymmetries in gene flow among the major mtDNA clades. Based on the nonexclusivity of mtDNA haplotypes, nuclear gene flow among populations and wide zones of phenotypic intergradation, S. magister appears to represent a single geographically variable and widespread species.     

Macroecology meets macroevolution: evolutionary niche dynamics in the seaweed Halimeda

Aim Because of their broad distribution in geographical and ecological dimensions, seaweeds (marine macroalgae) offer great potential as models for marine biogeographical inquiry and exploration of the interface between macroecology and macroevolution. This study aims to characterize evolutionary niche dynamics in the common green seaweed genus Halimeda, use the observed insights to gain understanding of the biogeographical history of the genus and predict habitats that can be targeted for the discovery of species of special biogeographical interest. Location Tropical and subtropical coastal waters. Methods The evolutionary history of the genus is characterized using molecular phylogenetics and relaxed molecular clock analysis. Niche modelling is carried out with maximum entropy techniques and uses macroecological data derived from global satellite imagery. Evolutionary niche dynamics are inferred through application of ancestral character state estimation. Results A nearly comprehensive molecular phylogeny of the genus was inferred from a six‐locus dataset. Macroecological niche models showed that species distribution ranges are considerably smaller than their potential ranges. We show strong phylogenetic signal in various macroecological niche features. Main conclusions The evolution of Halimeda is characterized by conservatism for tropical, nutrient‐depleted habitats, yet one section of the genus managed to invade colder habitats multiple times independently. Niche models indicate that the restricted geographical ranges of Halimeda species are not due to habitat unsuitability, strengthening the case for dispersal limitation. Niche models identified hotspots of habitat suitability of Caribbean species in the eastern Pacific Ocean. We propose that these hotspots be targeted for discovery of new species separated from their Caribbean siblings since the Pliocene rise of the Central American Isthmus.     

Using biogeographical history to inform conservation: the case of Preble's meadow jumping mouse

The last Pleistocene deglaciation shaped temperate and boreal communities in North America. Rapid northward expansion into high latitudes created distinctive spatial genetic patterns within species that include closely related groups of populations that are now widely spread across latitudes, while longitudinally adjacent populations, especially those near the southern periphery, often are distinctive due to long‐term disjunction. Across a spatial expanse that includes both recently colonized and long‐occupied regions, we analysed molecular variation in zapodid rodents to explore how past climate shifts influenced diversification in this group. By combining molecular analyses with species distribution modelling and tests of ecological interchangeability, we show that the lineage including the Preble's meadow jumping mouse (Zapus hudsonius preblei), a US federally listed taxon of conservation concern, is not restricted to the southern Rocky Mountains. Rather, populations along the Front Range are part of a single lineage that is ecologically indistinct and extends to the far north. Of the 21 lineages identified, this Northern lineage has the largest geographical range and low measures of intralineage genetic differentiation, consistent with recent northward expansion. Comprehensive sampling combined with coalescent‐based analyses and niche modelling leads to a radically different view of geographical structure within jumping mice and indicates the need to re‐evaluate their taxonomy and management. This analysis highlights a premise in conservation biology that biogeographical history should play a central role in establishing conservation priorities.     

Dispersal traits linked to range size through range location, not dispersal ability, in Western Australian angiosperms

Aim  We examine the relative importance of seed dispersal mode in determining the range size and range placement in 524 species from six focal plant families (Agavaceae, Euphorbiaceae, Malvacaeae, Sapindaceae, Proteaceae and Fabaceae ( Acacia )).
Location  Western Australia.
Methods  Taxa were categorized by dispersal mode and life-form and their distributions modelled using maxent . Geographical range size was compared amongst dispersal mode, life-form and biome using phylogenetically independent contrasts. Geographical range placement was considered in a similar manner.
Results  Range size did not vary with dispersal mode (ant versus wind and vertebrate dispersal) or life-form, and instead varied primarily as a function of the biogeographical region in which a species was found. Range placement, however, did vary among dispersal modes, with the consequence that diversity of wind- and ant-dispersed plants increased with latitude while the diversity of vertebrate-dispersed plants was more evenly distributed.
Main conclusions  For the taxa studied, range sizes were a function of the biogeographical region in which species were found. Although differences in range size may exist among species differing in dispersal modes, they are likely to be far smaller than differences among species from different biogeographical regions. The trait most likely to affect species geographical range size, and hence rarity and risks associated with other threats, may simply be the geographical region in which that species has evolved.     

The relationships between abundance, range size and niche breadth in Central European tree species

Aim  Range size and niche breadth have been found to be positively related to abundance in many plant and animal groups. We tested these two relationships for the tree species flora of Central Europe; that is, for all 25 species that have their distribution centre in this region.
Location  Eurasia, with a focus on Central Europe.
Methods  We devised an abundance and niche variable classification system to transform the existing literature data into a semi-quantitative assessment of abundance and niche breadth (in terms of soil chemical and physical variables, and temperature) for each of the 25 tree species. Regression analyses between abundance, range size and niche breadth were conducted for the entire species sample and for subsets of species defined by their ecology or phylogeny.
Results  The relationship between abundance in the distribution centre and range size was weak for the Central European tree species. However, significant abundance–range size relationships were found for phylogenetically or ecologically more homogenous species groups (for example for trees of the order Rosales and for mid-successional tree species). Realized niche breadth was positively related to range size in the case of temperature, but not for soil-related variables. No relationship existed between niche breadth and abundance in the distribution centre.
Main conclusions  We hypothesize that the weak relationship between abundance and range size is primarily a consequence of substantial ecological and phylogenetic heterogeneity within this rather species-poor assemblage. The positive relationship between realized temperature niche breadth and range size emphasizes the strong influence of climatic variables on plant distribution patterns over continental or global scales.     

Explosive evolution of an ancient group of Cyphophthalmi (Arachnida: Opiliones) in the Balkan Peninsula

Aim  To investigate the phylogeny of the genus Cyphophthalmus in the Balkan Peninsula and to test the current recognition of 'phyletic lines' and phylogenetic groups proposed in previous studies in order to elucidate the biogeographical history of the region.
Location  Europe, Balkan Peninsula, Adria microplate.
Methods  Two mitochondrial (cytochrome c oxidase subunit I and 16S rRNA) and two nuclear (28S rRNA and 18S rRNA) markers were used to infer the phylogenetic history of the group. Molecular dating with relaxed molecular clocks was used to elucidate the relative time of diversification within the genus Cyphophthalmus and its constituent lineages.
Results  Our analyses confirm the monophyly of the genus Cyphophthalmus , and that of the Aegean and gjorgjevici lineages, whereas the 'Dinaric lineage' appears paraphyletic.
Main conclusions  We show that the genus Cyphophthalmus is an old endemic from the Balkan biogeographical region, which gave origin to at least three main lineages. Those lineages have diversified within overlapping ranges. According to our molecular dating, they have also diversified within the same timeframe. The Dinaric Alps, although presenting a large number of species, cannot be inferred as the centre of origin of the group. Instead, the biogeographical evolution of the genus could be related to the palaeogeographic history of the Adria microplate.     

The past and future influence of geographic information systems on hybrid zone, phylogeographic and speciation research

Over the past two decades geographers have developed an increasingly sophisticated technology termed a geographic information system (GIS). A GIS has the ability to store, map and analyse spatial data. The powerful analytical capabilities of a GIS could serve to enhance our understanding of the spatial component of the evolutionary process. In particular, phylogeographers, hybrid zone and speciation researchers could benefit enormously from incorporating this sophisticated technology from the discipline of geography, as they have done so readily from other disciplines (e.g. genetics). Indeed, an increasing number of researchers in these fields are beginning to include GIS analyses into their research programmes. Some of this integration has taken the form of analysing the spatial relationship between populations and hybrid zones. Several other researchers have also begun to incorporate GIS into their work through the use of GIS-based niche models. These models estimate a multidimensional niche for a species using known geo-referenced populations and digital climate maps. Here, I review the recent integration of GIS and GIS-based predictive niche models into the above evolutionary sub-disciplines. I also describe evolutionary analyses that could be further enhanced through the implementation of GIS.     

The old wasp and the tree: fossils, phylogeny and biogeography in the Orussidae (Insecta, Hymenoptera)

The phylogenetic relationships of the fossil orussid taxa Mesorussus taimyrensis and Minyorussus luzzi are examined by analysing them together with a large data set compiled previously for the extant Orussidae. The fossils are placed in an unresolved trichotomy with the extant Orussidae. The phylogeny is used for evaluating the hypothesis that the ancestors of the family had reduced body size; the results of this analysis are inconclusive. The biogeographical history of the Orussidae is explored. The common ancestor of the family was probably widespread, the initial splitting events taking place prior to or coinciding with the separation of Laurasia from Gondwana. Later putative vicariance events can be correlated with the gradual breakup of Gondwana. However, the biogeographical history of the Orussidae is dominated by speciation within regions and dispersal. The minimum age of the common ancestor of the Orussidae is >180 Myr when estimated from the biogeographical pattern, >95 Myr when estimated from the phylogenetic position of the fossils; the earlier date is considered to be the most likely.  © 2004 The Linnean Society of London , Biological Journal of the Linnean Society , 2004, 82 , 139–160.     

节肢动物吐卓虫咬痕化石在云南昆明附近寒武纪早期关山生物群的发现及意义*

本文报道了一块来自云南省昆明市附近寒武纪第二世第四期关山生物群具咬痕的双瓣壳节肢动物吐卓虫 (Tuzoia)化石, 系吐卓虫咬痕化石在全球范围的首次发现。该发现证实作为主动捕食者的吐卓虫很可能被大型捕食者(如奇虾类或莱德利基虫类三叶虫等)捕食, 说明寒武纪早期的海洋生物群落已经具有高度复杂化的食物链, 为进一步了解吐卓虫的生态位及深入探讨寒武纪大爆发时期海洋生态系统食物网结构提供了新的信息。     

节肢动物吐卓虫咬痕化石在云南昆明附近寒武纪早期关山生物群的发现及意义*

本文报道了一块来自云南省昆明市附近寒武纪第二世第四期关山生物群具咬痕的双瓣壳节肢动物吐卓虫 (Tuzoia)化石, 系吐卓虫咬痕化石在全球范围的首次发现。该发现证实作为主动捕食者的吐卓虫很可能被大型捕食者(如奇虾类或莱德利基虫类三叶虫等)捕食, 说明寒武纪早期的海洋生物群落已经具有高度复杂化的食物链, 为进一步了解吐卓虫的生态位及深入探讨寒武纪大爆发时期海洋生态系统食物网结构提供了新的信息。     

Normal giants? Temporal and latitudinal shifts of Palaeozoic marine invertebrate gigantism and global change

During and after the Cambrian explosion, very large marine invertebrate species have evolved in several groups. Gigantism in Carboniferous land invertebrates has been explained by a peak in atmospheric oxygen concentrations, but Palaeozoic marine invertebrate gigantism has not been studied empirically and explained comprehensively. By quantifying the spatiotemporal distribution of the largest representatives of some of the major marine invertebrate clades (orthoconic cephalopods, ammonoids, trilobites, marine eurypterids), we assessed possible links between environmental parameters (atmospheric or oceanic oxygen concentrations, ocean water temperature or sea level) and maximum body size, but we could not find a straightforward relationship between both. Nevertheless, marine invertebrate gigantism within these groups was temporally concentrated within intervals of high taxonomic diversity (Ordovician, Devonian) and spatially correlated with latitudes of high occurrence frequency. Regardless of whether temporal and spatial variation in sampled diversity and occurrence frequency reflect true biological patterns or sampling controls, we find no evidence that the occurrences of giants in these groups were controlled by optimal conditions other than those that controlled the group as a whole; if these conditions shift latitudinally, occurrences of giants will shift as well. It is tempting to attribute these shifts to contemporary changes in temperature, oxygen concentrations in the atmosphere and the oceans as well as global palaeogeography over time, but further collection‐based studies are necessary on finer stratigraphic and phylogenetic resolution to corroborate such hypotheses and rule out sampling or collection biases.     

贵州剑河中寒武世中期甲劳组水母状化石的发现

贵州剑河革东镇八郎村南甲劳组中部钙质白云岩中新近发现的具有粗强放射状辐管的水母状化石和其下凯里组中具细辐管及同心环的拟轮盘水母(Pararotadiscus)有明显区别,属于伊尔东钵科(Eldoniidae)。其层位晚于中寒武世早期凯里生物群中拟轮盘水母(Pararotadiscus)层位1个化石带,属中寒武世中期,是该类化石在中国的最高层位,相当于北美布尔吉斯页岩生物群中Eldonia化石层位。     

Using ecological niche modelling to evaluate niche stability in deep time

Aim To investigate relative niche stability in species responses to various types of environmental pressure (biotic and abiotic) on geological time‐scales using the fossil record. Location The case study focuses on Late Ordovician articulate brachiopods of the Cincinnati Arch in eastern North America. Methods Species niches were modelled for a suite of fossil brachiopod species based on five environmental variables inferred from sedimentary parameters using GARP and Maxent . Niche stability was assessed by comparison of (1) the degree of overlap of species distribution models developed for a time‐slice and those generated by projecting niche models of the previous time‐slice onto environmental layers of a second time‐slice using GARP and Maxent , (2) Schoener’s D statistic, and (3) the similarity of the contribution of each environmental parameter within Maxent niche models between adjacent time‐slices. Results Late Ordovician brachiopod species conserved their niches with high fidelity during intervals of gradual environmental change but responded to inter‐basinal species invasions through niche evolution. Both native and invasive species exhibited similar levels of niche evolution in the invasion and post‐invasion intervals. Niche evolution was related mostly to decreased variance within the former ecological niche parameters rather than to shifts to new ecospace. Main conclusions Although the species examined exhibited morphological stasis during the study interval, high levels of niche conservatism were observed only during intervals of gradual environmental change. Rapid environmental change, notably inter‐basinal species invasions, resulted in high levels of niche evolution among the focal taxa. Both native and invasive species responded with similar levels of niche evolution during the invasion interval and subsequent environmental reorganization. The assumption of complete niche conservatism frequently employed in ecological niche modelling (ENM) analyses to forecast or hindcast species geographical distributions is more likely to be accurate for climate change studies than for invasive species analyses over geological time‐scales.     

Detecting the influence of climatic variables on species distributions: a test using GIS niche-based models along a steep longitudinal environmental gradient

Aim  To investigate the influence of climate variables in shaping species distributions across a steep longitudinal environmental gradient.
Location  The state of Oklahoma, south-central United States.
Methods  We used Geographical Information Systems (GIS) niche-based models to predict the geographic distributions of six pairs of closely related amphibian and reptile species across a steep longitudinal environmental gradient. We compared results from modelling with actual distributions to determine whether species distributions were primarily limited by environmental factors, and to assess the potential roles of competition and historical factors in influencing distributions.
Results  For all species pairs, GIS models predicted an overlap zone in which both species should occur, although in reality in some cases this area was occupied by only one of the species. We found that environmental factors clearly influence the distributions of most species pairs. We also found evidence suggesting that competition and evolutionary history play a role in determining the distributions of some species pairs.
Main conclusions  Niche-based GIS modelling is a useful tool for investigating species distribution patterns and the factors affecting them. Our results showed that environmental factors strongly influenced species distributions, and that competition and historical factors may also be involved in some cases. Furthermore, results suggested additional lines of research, such as ecological comparisons among populations occurring inside and outside predicted overlap zones, which may provide more direct insight into the roles of competitive interactions and historical factors in shaping species distributions.