Elkin A. Noguera-Urbano

Areas of endemism: travelling through space and the unexplored dimension

The current concept of areas of endemism assumes that they are geographic areas where there is spatial congruence of at least two endemic taxa. When this congruence is non-random, areas of endemism are explained by historical and ecological factors. Space has been the main dimension of analysis of areas of endemism, and the role of the time dimension in areas of endemism remains unclear. Phylogenetic information is a source of temporal information to explore the structure of the areas of endemism. I review the concept of areas of endemism and discuss their conceptual models (structure and boundaries). I propose four scenarios about the structural integration of endemic taxa in the space-time dimensions into areas of endemism. A better understanding of how to interpret areas of endemism can be analysed using phylogenetic information from endemic taxa to test simultaneous divergence and to propose temporal strata. Although the evolutionary relationships of the space and time dimensions have rarely been characterized in areas of endemism, I used this conceptual framework to interpret the Andean area of endemism and its evolution.

Mammal species richness and biogeographic structure at the southern boundaries of the Nearctic region

Abstract We analyzed whether the spatial variation in mammal species richness reflects the southern boundaries of the Nearctic region as previously established by endemism patterns. Records from 710 mammal species were drawn on a map of North America (from Canada and Alaska to Panama) gridded at 4° latitude-longitude. We evaluated the probable existence of unknown species through three richness estimators (Chao2, ICE, and Jack1), modeled the potential distribution of species, and mapped the predicted pattern of species richness through the number of coexisting potential distributions. The poorest grid cells are in the northern areas, whereas the richest ones are in the southern areas, coinciding with the pattern of collecting points. The average richness of 4° grid cells comprising the Nearctic region was 18 species, and the richest 4° grid cells had 150 species, coinciding with the 26° latitude. From the 406 mammal species of the Nearctic region, 104 are restricted to it, and 305 species situated south of it are not distributed in the region. The map of predicted richness shows the classical latitudinal diversity gradient, with the number of species increasing to the tropics. We conclude that the Nearctic region has a low mammal richness, with a richness pattern corresponding with previously described patterns of endemism, with a boundary situated at 26°–30° latitude.

Methodological Issues in Modern Track Analysis

Track analysis is the core of panbiogeographic analysis. In this work, we reflect on the formalization of track analysis, its methodological issues, and interpretations by using new software developments and from a contemporary evolutionary biogeographical viewpoint. From a geometric perspective, we analyze the meaning of a minimal spanning tree, considering that Prim’s algorithm is the most commonly used to draw individual tracks. We then show the existing methodologies (graphs, PAE, combined method, AE) and software packages (Trazos2004, Croizat, Martitracks, fossil) used to perform track analysis. Finally, we illustrate a track analysis using Nearctic mammals as an example. Based on our review, connectivity matrix analysis may be the best way to associate individual tracks into generalized tracks because it compares the minimal spanning tree topologies. However, it is the most demanding of all methods, since it requires a high spatial congruence among species, and therefore more algorithmic development.

The Neotropical region sensu the areas of endemism of terrestrial mammals

Abstract. The mammals are the biological group initially analysed by Wallace to define the Neotropical region (NR). Their areas of endemism (Ae) are considered historical patterns, which have been used to describe biogeographic schemes. However, the Ae at regional scale are currently unclear. In the present study, we analyse Ae of mammals at the regional scale and compare them with previous biogeographic schemes of the NR. The Ae of Neotropical terrestrial mammals were identified using the endemicity analysis (software NDM/VNDM). Our results showed that the NR is composed of 10 Ae, supported by 82 endemic taxa (6 families, 29 genera, and 47 species). The Ae showed a NR with multiple boundaries and with a core of higher overlap of the areas of endemism (OAE) from Veracruz and the Pacific coasts of Mexico to the southern limit of Amazonia in Brazil. The NR boundaries vary strikingly with latitude, with substantially more overlapping areas of endemism in the tropical biomes than in the temperate biomes of America. This pattern of OAE is consistent with the higher mammal-species richness zone within the tropical biomes and other biogeographic patterns such as higher productivity and spatial heterogeneity.

Environmental factors related to biogeographical transition zones of areas of endemism of Neotropical mammals

Abstract. Biogeographical transition zones are areas of a complex biotic mixture located at the borders between biogeographical units. Climatic, physical and ecological factors should play an important role in allowing coexistence of different biotic elements in the transition zone. Here, we explore the relationship between environmental factors and biogeographical transition zones, defined by Neotropical mammal distributions, by a model selection approach based on the Akaike information criterion and accounting for the spatial structure in the data. We detected three areas of high overlap between mammalian areas of endemism. Two of them corresponded to the well-established regional-level transition zones, namely Mexican (MTZ) and South American (SATZ) transition zones; the third was one located in south-eastern Brazil, approximately between the Paraná and Chacoan dominion that we call The Atlantic Forest integration zone (AF). Only one explicative variable was shared by the three transitions zones (precipitation of the warmest quarter). However, shared variables with great explanatory power indicated two environmental aspects as facilitators for the coexistence of different biotic components in a given geographical area. The first one was the heterogeneity component, either topographic for the SATZ and MTZ or climatic for the AF. The second one was related non-extreme thermal conditions: precipitation of the warmest quarter, interpreted as a thermal buffer, shared by AF and SATZ, and isothermality shared by MTZ and SATZ.

On the distribution of the Brazilian porcupine Coendou prehensilis (Erethizontidae) in Colombia

Abstract The Brazilian porcupine Coendou prehensilis is distributed from northwestern South America to northeastern Paraguay and northwestern Argentina. In Colombia, it is present mainly in the Caribbean, the eastern Llanos and the Andean regions, which correspond to six of the biogeographical provinces of the country. Its presence in the Colombian Amazon region has been suggested based on records from neighboring countries such as Ecuador, Venezuela and Brazil. However, no voucher specimens or additional evidence that corroborates the presence of the species in that region of Colombia is known. Based on the review of specimens deposited in Colombian collections, analyses of photographic records, and the literature, the presence of the species in the Colombian Amazon is confirmed, and its distribution in the country updated. Overall, we found 36 records of C. prehensilis in Colombia, of which seven correspond to the Colombian Amazon (four photographic records and three specimens). A genetic analysis based on cytochrome-b suggests that this species is genetically uniform throughout its distributional range. These new records make C. prehensilis the most widespread species of the genus among natural regions and biogeographic provinces of Colombia. Other species are restricted to one or two provinces.