Areas of endemism of the Patagonian steppe: an approach based on insect distributional patterns using endemicity analysis

Aims  To delimit areas of endemism in the Patagonian steppe using endemicity analysis (EA), which evaluates areas of endemism by means of an endemicity index, and to compare the resulting endemic areas with those proposed for the Patagonian steppe by previous authors.
Location  The Patagonian steppe, a region of South America found approximately below parallel 36° S to the east of the Andes Mountains.
Methods  Distributional data for 159 species of insects collected in the Patagonian steppe, and consisting of 1317 georeferenced samples were used to identify areas of endemism. A data grid of presence and absence (with cells of 1° × 1°) was constructed. Initially, two different types of EA were performed, seeking areas defined by 'four or more' species. A first analysis was performed without taking into consideration those quadrats where no species had been recorded (empty quadrats), which in many cases meant a discontinuous distribution. The second analysis was performed assuming a continuous distribution for each species. A third analysis, assuming continuous distributions, was performed using 'three or more' as the number of species necessary for an area to be identified as an endemic area.
Results  In the first two analyses, EA recognized the same five areas of endemism: western Patagonia, south-western Payunia, northern Suabandean, southern Subandean and Austral Patagonia. The results of the third analysis allowed the identification of three more areas of endemism: northern Payunia, Chubutian and Santacrucian.
Main conclusions  We identified five areas of endemism for the Patagonian steppe, some of which have been defined in previous contributions. These areas are: Western Patagonia, Payunia and Subandean Patagonia (which can be divided into septentrional and meridional), Central Patagonia (Chubutence and Santacrucense) and Austral Patagonia.     

Ecological and historical factors affecting distribution pattern and richness of endemic plant species: the case of the Maritime and Ligurian Alps hotspot

The aim of this study was to test a method to locate all the foci, centres, and areas of endemism in a biodiversity hotspot in order to understand the influence of ecological and historical factors on the distribution pattern and to identify priority areas for future conservation projects. The study area was the Maritime and Ligurian Alps hotspot.
Analyses were performed on the presence/absence matrix of 36 vascular plant taxa endemic to the study area. For each operational geographical unit, the number of endemic taxa present was counted. Additionally, the weighted endemism value was calculated. Areas of endemism were distinguished using cluster analysis and parsimony analysis of endemicity. The influence of ecological characteristics and historical factors was evaluated using Multi-Response Permutation Procedure and the Nonparametric Multiplicative Regression. The Indicator Species Analysis (INDVAL) method was used to identify the species characterizing the areas of endemism. Our results show the importance and location of four main areas of endemism within the Maritime and Ligurian Alps and explain the distribution pattern of endemic plants. These areas are easily interpreted by historical and ecological factors, and INDVAL indicates which taxa took part in the history of each endemism area.     

Areas and algorithms: evaluating numerical approaches for the delimitation of areas of endemism in the Canary Islands archipelago

Aim Areas of endemism are the fundamental units of cladistic biogeographical analysis but there is no consensus on the most appropriate method for their delimitation. In this paper, the relative performance of a number of algorithmic approaches for the delimitation of areas of endemism is investigated within the context of the Canary Islands flora, and areas of endemism within the Canary Islands archipelago are defined. Location The Canary Islands. Methods A data matrix comprising the distributions of 609 endemic spermatophyte taxa (c. 90% of the endemic flora) scored on a 10 × 10 km UTM grid was analysed using: (1) UPGMA (unweighted pair group method with arithmetic mean) clustering of Jaccard and Kulczynski similarity coefficient matrices, (2) parsimony analysis of endemicity (PAE), and (3) the program ndm (eNDeMism). The performance of each method was then determined by the extent to which the resulting areas of endemism met three criteria: (1) possession of two or more strict endemic taxa, (2) diagnosability, and (3) geographical contiguity. Results Each of the four methods resulted in substantially different sets of areas. ndm analysis resolved 17 areas of endemism consistent with all three criteria, and collectively these accounted for 59% of all cells. In the hierarchical analyses none of the methods recovered more than eight areas of endemism, and the total coverage of cells ranged from 13% to 33% when the results were confined to intra‐island areas of endemism. Main conclusions ndm outperforms hierarchical clustering methods in terms of both the number of intra‐island areas of endemism delimited that meet the three evaluation criteria and the total coverage of those areas. ndm may also be considered preferable because it is non‐hierarchical, incorporates spatial information into the delimitation of areas, and permits overlap between areas of endemism where there is evidence to support it. The results support the use of ndm as the most appropriate method currently available for the delimitation of areas of endemism. The areas of endemism identified by the ndm analysis are discussed.     

Biodiversity and biogeography of the avifauna of the Sierra Madre Occidental,Mexico

The Sierra Madre Occidental (SMOc) is located in the boundary between the Nearctic and Neotropical regions, area which has been considered as a complex transition zone. We analysed biogeographic patterns of its resident avifauna, including species richness, endemism, and biotic regionalization by analysing presence-absence matrices of 148 species of resident-terrestrial birds. We created the species richness maps by overlapping potential distribution maps obtained for each species via species distribution models (SDMs). To depict biogeographic patterns, we used strict consensus cladograms from parsimony analyses of endemicity (PAE) and phenograms from an unweighted pair-group method with arithmetic average clustering algorithm. The Pacific slope of the SMOc contains the highest species richness, decreasing towards the northeast, and reflected in endemic and endangered species richness patterns. The PAE resulted in one area of endemism represented by the whole SMOc, outlining a divided area in its Pacific slope. The cluster analyses divided the area into two. One group towards the Pacific slope, delimited by the mountain ridge and characterized by tropical vegetation types and Mexican-Mesoamerican affinities; the other group is located towards the east and northeast, characterized by arid and temperate types of vegetation and Nearctic affinities. These results evidence a transition from a tropical to a temperate composition of bird species. In this way the location for a boundary between the Nearctic and the transition zone, for birds in this part of Mexico, is restricted to these highest elevations.     

Areas of endemism and patterns of diversity for aphids of the Qinghai-Tibetan Plateau and the Himalayas

Aim  The study aimed to identify areas of endemism for aphids in the Qinghai-Tibetan Plateau and the Himalayas (QTPH), and to test congruence between patterns of endemism and patterns of overall species richness identified in a previous study.
Location  The QTPH.
Methods  A distribution data base of 326 endemic aphids in the QTPH was compiled. The study area was divided into a grid of 2°× 2° operative geographical units. Parsimony analysis of endemicity (PAE) was used to identify areas of endemism, and the diversity patterns of endemic species were then mapped using GIS.
Results  We identified 326 endemic species belonging to 138 genera within Adelgidae and 14 subfamilies of Aphididae. Five areas of endemism were found using PAE analysis: the eastern Himalayas, the western Himalayas, north-western Yunnan, southern Tibet and the eastern QTPH. Maps of patterns of endemism identified four major centres for endemic aphids, namely the western Himalayas, the eastern Himalayas (or Sikkim-Assam Himalayas), north-western Hengduan Mountains and the mountains of southern Gansu Province, and three minor centres, southern Tibet, south-eastern Tibet and the eastern Qinghai Province in the north-eastern QTPH.
Main conclusions  Our study identifies major centres of aphid endemism. Furthermore, there is a noticeable congruence between patterns of endemism and patterns of species richness. The patterns of endemism were most likely influenced by the recent uplift of the QTPH.     

Endemic regions of the vascular flora of the peninsula of Baja California,Mexico

Question: Can we recognize areas of high endemism and high endemic richness, using data from collections, and what are the ecological variables that best explain these areas? Location: Peninsula of Baja California, Mexico. Methods: We analysed the distribution of 723 endemic vascular plants species along the peninsula of Baja California and neighbouring islands distributed in 218 cartographic cells 15’ x 20’ in size. By means of a residual analysis, we identified areas of significantly high endemic species richness, and we calculated the degree of endemicity (or rarity) in each cell by giving to each species a weight factor inversely proportional to the land area it covers. Results: Nine regions of high‐endemicity and/or high endemic species richness were found. Discussion and conclusions: The analyses of rarity and endemic species richness showed two contrasting scenarios: High endemicity values in oceanic and sky islands accounts for a high number of species with a restricted distribution, promoted most likely by genetic isolation and high environmental heterogeneity. High endemic richness along the peninsular coast is related to ecotonal transition along vegetation types. After correcting for collection effort (i.e. the number of specimens collected within a cell), we found the phytogeographic region and altitudinal heterogeneity to be the variables that best predicted endemic richness. Both high endemism and high endemic richness have distinct geographic patterns within our study region. The nine endemic regions provide elements for priority definitions in future conservation programs.     

Cladistic analysis of distributions and endemism (CADE): using raw distributions of birds to unravel the biogeography of the South American aridlands

Aim To use published distributional and taxonomic information on Neotropical birds in a cladistic analysis of distributions and endemism (CADE) to generate a testable hypothesis of area‐relationships for the arid areas of endemism, particularly those of Central South America (the ‘arid diagonal’), and to clarify the different methodologies commonly associated with parsimony analysis of endemicity (PAE). Location South America. Methods Cladistic analysis of distributions and endemism. Results We obtain a tree where the relationships of most areas are resolved, and we find support for an exclusive clade of Central South American areas, with the Caatinga as sister to both the Chaco and Cerrado. Main conclusions There is a substantial amount of historical signal in avian distributions, when large numbers of taxa and multiple taxonomic levels are considered. Ecological noise and historical information are more easily distinguished in CADE analyses than they would be in PAE analyses. Based on our results we predict that among aridland birds, the Cerrado and Chaco species will be more closely related to each other than to Caatinga species.     

A protocol for the delimitation of areas of endemism and the historical regionalization of the Brazilian Atlantic Rain Forest using harvestmen distribution data

The concept of areas of endemism (AoEs) has rarely been discussed in the literature, even though the use of methods to ascertain them has recently increased. We introduce a grid‐based protocol for delimiting AoEs using alternative criteria for the recognition of AoEs that are empirically tested with harvestmen species distributions in the Atlantic Rain Forest. Our data, comprising 778 records of 123 species, were analysed using parsimony analysis of endemicity and endemicity analysis on four different grids (two cell sizes and two cell placements). Additionally, we employed six qualitative combined criteria for the delimitation of AoEs and applied them to the results of the numerical analyses in a new protocol to objectively delimit AoEs. Twelve AoEs (the most detailed delimitation of the Atlantic Rain Forest so far) were delimited, partially corroborating the main divisions previously established in the literature. The results obtained with the grid‐based methods were contradictory and were plagued by artefacts, probably due to the existence of different endemism patterns in one cell or to a biogeographical barrier set obliquely to latitudinal and longitudinal axes, for example. Consequently, the congruence patterns found by them should not be considered alone; qualitative characteristics of species and clade distributions and abiotic factors should be evaluated together. Mountain slopes are the main regions of endemism, and large river valleys are the main divisions. Refuges, marine transgressions and tectonic activity seem to have played an important role in the evolution of the Atlantic Rain Forest.     

Areas of endemism in the Nearctic: a case study of 1339 species of Miridae (Insecta: Hemiptera) and their plant hosts

Areas of endemism are essential first hypotheses in investigating historical biogeography, but there is a surprising paucity of such hypotheses for the Nearctic region. Miridae, the plant bugs, are an excellent taxon to study in this context, because this group combines high species diversity, often small distribution ranges, a history of modern taxonomic revisions, and comprehensive electronic data capture and data cleaning that have resulted in an exceptionally error‐free geospatial data set. Many Miridae are phytophagous and feed on only one or a small number of host plant species. The programs ndm/vndm are here used on plant bug and plant data sets to address two main objectives: (i) identify areas of endemism for plant bugs based on parameters used in a recent study that focused on Nearctic mammals; and (ii) discuss hypotheses on areas of endemism based on plant bug distributions in the context of areas identified by their host plant species. Given the narrow distribution ranges of many species of Miridae, the analytical results allow for tests of the prediction that areas of endemism for Miridae are smaller and more numerous, especially in the Western Nearctic, than are those of their host plants. Analyses of the default plant bug data set resulted in 45 areas of endemism, 35 of them north of Mexico and many located in the Western Nearctic; areas in the Nearctic are more numerous and smaller than those identified by mammals. The host plant data set resulted in ten areas of endemism, and even though the size range of areas is similar between the Miridae and plant data sets, the average area size is smaller in the Miridae data set. These results allow for the conclusion that the Miridae indeed present a valuable model system to investigate areas of endemism in the Nearctic.     

Biogeographic regions of North American mammals based on endemism

Since the 19th Century, two regions have been recognized for North American mammals, which overlap in Mexico. The Nearctic region corresponds to the northern areas and the Neotropical region corresponds to the southern ones. There are no recent regionalizations for these regions under the criterion of endemism. In the present study, we integrate two methods to regionalize North America, using species distribution models of mammals: endemicity analysis (EA) and parsimony analysis of endemicity (PAE). EA was used to obtain areas of endemism and PAE was used to hierarchize them. We found 76 consensus areas from 329 sets classified in 146 cladograms, and the strict consensus cladogram shows a basal polytomy with 14 areas and 16 clades. The final regionalization recognizes two regions (Nearctic and Neotropical) and a transition zone (Mexican Transition Zone), six subregions (Canadian, Alleghanian, Californian‐Rocky Mountain, Pacific Central America, Mexican Gulf‐Central America, and Central America), two dominions (Californian and Rocky Mountain), and 23 provinces. Our analysis show that North America is probably more complex than previously assumed. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 485–499.     

Biogeographic analysis of endemic cacti of the Sierra Madre Oriental, Mexico

The distribution of cacti species that inhabit the Sierra Madre Oriental (SMO) was analysed. Grid-cells were analysed using parsimony analysis of endemicity (PAE) and endemism indices. Areas characterized by their diagnostic species were determined, aiming to propose areas for the conservation of threatened cacti. Distributional data were obtained from 1936 herbarium specimens, electronic information, and from field collections. Eight areas of endemism and three main clades were obtained from the grid-cell analysis. Areas obtained from the endemism indices are very similar to those obtained with the PAE, but differ in the association of grid-cells. PAE showed endemism patterns indicating that southern and central sections of the SMO province are the areas richest in geographically-restricted species. The results obtained with different endemism indices detected more or less the same areas, although the importance level is different. The corrected weighted endemism index can be considered as a reliable measure of endemism because it is unrelated to species richness. A regionalization of the SMO in three subprovinces is suggested, supported by characteristic cacti taxa and the existence of natural barriers.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 373–389.     

An optimality criterion to determine areas of endemism

A formal method was developed to determine areas of endemism. The study region is divided into cells, and the number of species that can be considered as endemic is counted for a given set of cells (= area). Thus, the areas with the maximum number of species considered endemic are preferred. This is the first method for the identification of areas of endemism that implements an optimality criterion directly based on considering the aspects of species distribution that are relevant to endemism. The method is implemented in two computer programs, NDM and VNDM, available from the authors.     

Distributional patterns of Neotropical seasonally dry forest birds: a biogeographical regionalization

Neotropical seasonally dry forests (NSDFs) are widely distributed and possess high levels of species richness and endemism; however, their biogeography remains only partially understood. Using species distribution modelling and parsimony analysis of endemicity, we analysed the distributional patterns of the NSDF avifauna in order to identify their areas of endemism and provide a better understanding of the historical relationships among those areas. The strict consensus trees revealed 17 areas of endemism for NSDFs, which involve four large regions: Baja California, Caribbean–Antilles islands, Mesoamerica and South America. These well-resolved clades are circumscribed by geographical and ecological barriers associated with the Gulf of California, the leading edge of the Caribbean plate, the Tehuantepec Isthmus, the Polochic–Motagua fault, the Nicaragua Depression, the Chocó forest, the Amazon basin and the Andean Cordillera. Relationships among groups of NSDFs found here suggest that evolution of their avifauna involved a mixture of vicariance and dispersal events. Our results support the idea of independent diversification patterns and biogeographical processes in each region, including those previously associated with the Pleistocene Arc Hypothesis for NSDFs of south-eastern South America. This study provides a biogeographical framework to open new lines of research related to the biotic diversification of NSDFs.     

Distributional modelling and parsimony analysis of endemicity of Senecio in the Mediterranean-type climate area of Central Chile

Aim Floristic blocks and areas of endemism resulting from a parsimony analysis of endemicity (PAE) using raw floristic data versus data generated from distributional modelling for 130 species in the genus Senecio Tourn. ex L. distributed in the Mediterranean‐type climate area of Central Chile were compared, and the results were used to identify conservation priorities for the flora of the region. Location Central Chile, between 30° and 38° S. Methods Using herbarium records, a species × area matrix consisting of presence/absence data was constructed from a 0.5° × 0.5° grid. Distributional modelling techniques incorporating vegetation formations, elevation and the contagion index were used to interpolate floristic composition of poorly known areas. Parsimony analysis of endemicity was used to identify floristic blocks and areas of endemism. Results Using the number of most parsimonious trees as an index, distributional modelling greatly optimized the results of the PAE analysis. Three floristic blocks and four areas of endemism were suggested based on the PAE results using potential distribution data not incorporating the contagion index, while four blocks and two areas of endemism were suggested from the PAE results using potential distribution data incorporating the contagion index. Floristic blocks for the northern coast, southern Andes, and northern/central Andes were found, with some blocks showing divisions within them representing distinct geographic subunits. Major breaks between and within floristic blocks were identified at 32.5°–33° S and 34.5°–35° S. Main conclusions The floristic blocks identified with the distributional modelling and PAE correspond well to results from some previous studies and support hypothesized biogeographic divisions within Central Chile. The results were similar to those obtained from parallel analysis of the entire tree flora of Central Chile. The vegetative formation‐based distributional modelling produced robust and reproducible results when used along with PAE, especially when the contagion index was incorporated, and is a useful technique for area classification. The results demonstrate the utility of Senecio as an indicator genus for biogeography and conservation in southern South America.     

Richness and endemism of helminth parasites of freshwater fishes in Mexico

Distribution records of 152 adult helminth taxa parasites of freshwater fishes in Mexico were analysed to determine areas of high richness and endemism. Distribution maps were prepared for each taxon and overlaid onto a map of Mexico divided into 1 × 1 degree grid-cells. Richness was determined by counting recorded helminth species in each grid-cell. A corrected weighted endemism index was calculated for each grid-cell, and the relationship between richness and endemicity was analysed with an Olmstead–Tukey corner test of association. Five areas of high richness and endemism were identified: (1) Los Tuxtlas and the Papaloapan river basin, on the Gulf of Mexico; (2) the Grijalva-Usumacinta basin near the Gulf of Mexico coastal plain; (3) the Yucatan Peninsula; (4) the Sierra de Manantlán Biosphere Reserve in western Mexico; and (5) the Pátzcuaro lake, in central Mexico. The distribution of richness and endemism of helminth parasites of freshwater fishes in Mexico is congruent with distributional patterns described for other freshwater taxa in Mexico. Patterns of richness and/or endemism in the studied areas can be explained by the ichthyological composition of their bodies of water. The present study establishes an objective way of analysing the relationship between richness and endemicity, and suggests that helminths can make valuable contributions to regionalization of geographical areas and for identification of rich and biologically complex areas with potential for conservation of aquatic systems.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 435–444.     

Comparison between Parsimony Analysis of Endemicity (PAE), Endemicity Analysis (EA), and an alternative coding of Three-Distribution Statements based on hypothetical distributions

Areas of endemism are identified by a variety of methods, none of which is universally accepted. Performance of each method depends upon the variables chosen. Here, we compare Parsimony Analysis of Endemicity (PAE), Endemicity Analysis (EA), and a new coding method that we propose, Three-Distribution Statements (3DS). We rate performance based on the ability to identify hypothetical predefined patterns that represent non-conflicting, nested, and overlapping areas of endemism. Additionally, we also compared properties commonly used in analyses, such as shape and size of the area and the number of taxa involved. We found that 3DS has the best performance in retrieving predefined areas. EA is the only method that resolved a completely overlapping pattern, but it also found spurious patterns. Resolution with PAE always had intermediate precision and efficiency and so is not the best option for analysis of endemism. We recommend the use of 3DS together with EA as the best available option for hypothesizing areas of endemism.     

Ecoregion Prioritization Suggests an Armoury Not a Silver Bullet for Conservation Planning

In the face of accelerating species extinctions, map-based prioritization systems are increasingly useful to decide where to pursue conservation action most effectively. However, a number of seemingly inconsistent schemes have emerged, mostly focussing on endemism. Here we use global vertebrate distributions in terrestrial ecoregions to evaluate how continuous and categorical ranking schemes target and accumulate endangered taxa within the IUCN Red List, Alliance for Zero Extinction (AZE), and EDGE of Existence programme. We employed total, endemic and threatened species richness and an estimator for richness-adjusted endemism as metrics in continuous prioritization, and WWF''s Global200 and Conservation International''s (CI) Hotspots in categorical prioritization. Our results demonstrate that all metrics target endangerment more efficiently than by chance, but each selects unique sets of top-ranking ecoregions, which overlap only partially, and include different sets of threatened species. Using the top 100 ecoregions as defined by continuous prioritization metrics, we develop an inclusive map for global vertebrate conservation that incorporates important areas for endemism, richness, and threat. Finally, we assess human footprint and protection levels within these areas to reveal that endemism sites are more impacted but have more protection, in contrast to high richness and threat ones. Given such contrasts, major efforts to protect global biodiversity must involve complementary conservation approaches in areas of unique species as well as those with highest diversity and threat.     

Historical biogeography of South American freshwater fishes

Aim To investigate biogeographical patterns of the obligate freshwater fish order Characiformes. Location South America. Methods Parsimony analysis of endemicity, likelihood analysis of congruent geographical distribution, and partition Bremer support were used. Results Areas of endemism are deduced from parsimony analysis of endemicity, and putative dispersal routes from a separate analysis of discordant patterns of distribution. Main conclusions Our results demonstrate the occurrence of 11 major areas of endemism and support a preferential eastern–western differentiation of the characiforms in the Amazonian region, contrasting with the southern–northern differentiation of terrestrial organisms. The areas of endemism identified seem to be deeply influenced by the distribution of the emerged land during the 100‐m marine highstand that occurred during the late Miocene and allow us to hypothesize the existence of eight aquatic freshwater refuges at that time. The raw distribution of non‐endemic species supports nine patterns of species distribution across the 11 areas of endemism, two of which support a southern–northern differentiation in the eastern part of the Amazon. This result shows that the main channel of the Amazon limited dispersal between tributaries from each bank of the river. The levels of endemism further demonstrate that the aquatic freshwater refuges promoted allopatric speciation and later allowed the colonization of the lowlands. By contrast, the biogeographical pattern found in the western part of the Amazon is identified as a result of the Miocene Andean foreland dynamic and the uplift of the palaeoarches that promoted allopatric divergence across several sedimentary basins by the establishment of disconnected floodplains. The assessment of conflicting species distributions also shows the presence of seven putative dispersal routes between the Amazon, Orinoco and Paraná rivers. Our findings suggest that, rather than there being a single predominant process, the establishment of the modern South American freshwater fish biotas is the result of an interaction between marine incursions, uplift of the palaeoarches, and historical connections allowing cross‐drainage dispersal.     

Areas of endemism of arthropods in the Atlantic Forest (Brazil): an approach based on a metaconsensus criterion using endemicity analysis

An analysis of endemicity (NDM/VNDM) based on 6541 records from 791 species of arthropods was conducted aiming to delimitate areas of endemism (AEs) in the Atlantic Forest (Brazil). Nine analyses were run employing different analytical parameters of grid size and data extrapolation of species distribution, and their effects on the results were observed. The present study is the first to employ an analysis of sensitivity with UPGMA (unweighted pair group method with arithmatic mean) as a metaconsensus criterion to compare and select AEs resulting from analyses of endemicity with different analytical parameters. In total, 724 AEs grouped into 313 consensus areas were identified. With the metaconsensus criterion, 29 groups of areas were defined, most of them coinciding with the areas obtained in other studies, which confirms that the metaconsus criterion is a clear and objective method for comparing and selecting AEs. The results of the present imply that species of arthorpods respond differently to events and, moreover, that the geographical/climate features usually employed to explain distributional patterns of other taxa do not uniformly affect all species included in the study. The AEs identified in the present study represent a major advance in the search for quantitative distribution patterns in the Atlantic Rainforest, contributing to studies of historical biogeography and other approaches related to the conservation.     

Patterns of endemism in south-eastern Pacific benthic polychaetes of the Chilean coast

Aim In this study we evaluate patterns of endemism for benthic polychaete species along the southeastern Pacific coast of Chile. Our goals were (1) to describe latitudinal gradients of endemism and identify areas of high endemism, (2) to evaluate the effect of biogeographical limits on endemism patterns, and (3) to evaluate indirectly the role played by evolutionary dynamics on patterns of endemism. Location South‐eastern Pacific coast of Chile, ranging from Arica (18° S) to Cape Horn (56° S). Methods We used a list of 178 species of endemic, shallow benthic polychaetes to evaluate patterns of endemism. Parsimony analysis of endemicity (PAE) and the endemism index (EI) were used to evaluate hierarchical relationships of endemism between different latitudinal bands, and to identify areas with high degrees of endemism and differences in endemism. We evaluated the effect of biogeographical limits on endemic polychaete fauna by testing for the existence of geometric constraints (mid‐domain effect). The role of evolutionary dynamics on latitudinal patterns of endemism was evaluated with nestedness analysis (NA) using the temperature index. Results The PAE analysis indicated two large, separate areas of endemism: (1) the northern area between 18° S and 38° S, and (2) the southern area between 39° S and 56° S. The endemism index showed a maximum value (32 species) around 39°–41° S. Species‐richness curves of each 3° band of latitude showed a clear mid‐domain effect (69%), but the two maximum points of species richness at mid‐latitudes (36° S to 38° S and 39° S to 41° S) did not correspond to the mid‐domain peak in species richness, presenting a greater number of species than expected by the mid‐domain effect. The nestedness analysis showed that the number of genera reaches a maximum of 70 at mid‐latitudes (36°–41° S), decreasing towards both the northern and southern areas. The spatial distribution of the entire data set of endemic species showed a nested pattern (T° = 24.5°, P < 0.0001). Main conclusions Our results strongly support the existence of a latitudinal gradient of endemism for benthic polychaete species along the Chilean coast. The shape of this gradient is clearly non‐linear, with a marked peak of endemism occurring at mid‐latitudes (36°–41° S, endemism hotspot), which also corresponds to a peak in species richness. Furthermore, this hotspot is the midpoint separating two distinct areas of endemism to the north and south. We suggest that the observed pattern of endemism for benthic polychaete taxa of the Chilean coast can be explained by a combination of geometric constraints and historical mechanisms, such as the processes that affected the Chilean coast during the Neogene (e.g. ENSO, oxygen minimum zone, glaciations).