An evaluation of the influence of environment and biogeography on community structure: the case of Holarctic mammals

Abstract

Aim To evaluate the influence of environment and biogeographical region, as a proxy for historical influence, on the ecological structure of Holarctic communities from similar environments. It is assumed that similarities among communities from similar environments in different realms are the result of convergence, whereas their differences are interpreted as being due to different historical processes.Location Holarctic realm, North America and Eurasia above 25°N.Methods Checklists of mammalian species occurring in 96 Holarctic localities were collected from published sources. Species were assigned to one of 20 functional groups defined by diet, body size and three-dimensional use of space. The matrix composed of the frequencies of functional groups in the 96 localities is used as input data in a correspondence analysis (CA). The localities are classified into nine groups according to Bailey's ecoregions (used as a surrogate of regional climate), and the positions of the communities in the dimensions of the CA are compared in relation to ecoregion and realm. Partial regression was used to test for the relative influence of ecoregion and realm over each dimension and to evaluate the effect of biogeographical realm on the variation in the factor scores of the communities of the same ecoregion. ResultsIn some cases, mammalian communities from areas with similar regional climates exhibit convergence in community structure, irrespective of the biogeographical realm where they are located. However, all of them are clearly subdivided into Nearctic and Palearctic subsets. Differences in the composition of the regional pools only partially explain differences in local communities between realms.Main conclusions Holarctic mammalian communities from regions with widely different climates differ in ecological structure irrespective of their biogeographical location. On the other hand, the structures of Nearctic and Palearctic communities from regions of similar climate radically differ in some features. Thus, although present climatic conditions influence community structure, contingent historic processes associated with each region also play a major role in determining community structure.

Regional and environmental effects on the species richness of mammal assemblages

“…The overlap between regional and environmental variables (Hawkins et al, 2003a;our results) and the correlation between current and past climate (see, for example, Hawkins et al, 2005Hawkins et al, , 2007a demonstrate that geographic differences in species richness and community structure are linked not only to present-day environmental conditions but also to historical processes acting at evolutionary and ecological time-scales (see Hawkins et al, 2005;Svenning & Skov, 2005;Rodríguez et al, 2006). Although our results are restricted to terrestrial non-volant mammal assemblages, it is likely that they can be extrapolated to many other groups.…”

“…all orders except Chiroptera, Cetacea, and Pinnipedia) was used to calculate species richness in 311 localities distributed worldwide (see the data base description in Rodríguez, 1999; and examples of its application in Nieto et al, 2005 andRodríguez et al, 2006). For this analysis we selected the 224 sites ranging from 100 to 10,000 km 2 in area.…”

“…Among them, the characteristics of the sites where the species occur, including the environment (climate and habitat) and its physical characteristics (area and topographic and landscape heterogeneity), are frequently mentioned as the primary drivers of species richness (Kerr & Packer, 1997;Francis & Currie, 1998, 2003Waide et al, 1999;Jetz & Rahbek, 2001;Kerr et al, 2001;Rahbek & Graves, 2001;Currie et al, 2004;Tognelli & Kelt, 2004;Field et al, 2005;Scheiner & Willig, 2005). Communities are not, however, affected only by the characteristics of the site where they occur; they are also the result of the assembling of species from those available in the regional pool (Ricklefs, 2004), which includes the characteristics and evolutionary history of the species present in the regional pool (Nieto et al, 2005;Rodríguez et al, 2006;J. Hortal, J. Rodríguez, D. Nogués-Bravo, M. B. Araú jo & C. Rahbek, unpublished), the geomorphological and environmental characteristics of the region (Jetz & Rahbek, 2001;Rahbek & Graves, 2001), and region-specific historical variation in climate and habitat (see, for example, Hawkins & Porter, 2003;Hawkins et al, 2005;Svenning & Skov, 2005, 2007Montoya et al, 2007).…”

Large-scale patterns in morphological diversity and species assemblages in Neotropical Triatominae (Heteroptera: Reduviidae)

“…On the other hand, large-scale differences in climatic, vegetation, physiognomy and soil conditions that influence the structuring of species assemblages across biomes ( Rodríguez et al 2006 ) may underlie the regional associations of triatomine SR and MDiv with the presence of biomes.…”

Habitat preference of extant African bovids based on astragalus morphology: operationalizing ecomorphology for palaeoenvironmental reconstruction

“…Another approach is to classify species into ecological groups defined by their combination of diet, body size, and locomotor behavior and to use the absolute frequencies of these different ecological groups in different communities to construct a multidimensional eco-space. Distance in this eco-space measures ecological similarity, with more distant communities being more dissimilar to each other (Hertel and Lehman, 1998;Rodriguez, 2004;Rodriguez et al, 2006). In addition to comparing the structure of different communities, these approaches are useful for inferring the types and relative abundance of different habitats in a palaeocommunity.…”