Large-scale patterns of species richness and their causes are still poorly understood for most terrestrial invertebrates, although invertebrates can add important insights into the mechanisms that generate regional and global biodiversity patterns. Here we explore the general plausibility of the climate-based "water-energy dynamics" hypothesis using the latitudinal pattern of land-snail species richness across extensive topographically homogeneous lowlands of northern Eurasia. We established a 1480-km long latitudinal transect across the Western Siberian Plain (Russia) from the Russia-Kazakhstan border (54.5°N) to the Arctic Ocean (67.5°N), crossing eight latitudinal vegetation zones: steppe, forest-steppe, subtaiga, southern, middle and northern taiga, forest-tundra, and tundra. We sampled snails in forests and open habitats each half-degree of latitude and used generalized linear models to relate snail species richness to climatic variables and soil calcium content measured in situ. Contrary to the classical prediction of latitudinal biodiversity decrease, we found a striking unimodal pattern of snail species richness peaking in the subtaiga and southern-taiga zones between 57 and 59°N. The main south-to-north interchange of the two principal diversity constraints, i.e. drought stress vs. cold stress, explained most of the variance in the latitudinal diversity pattern. Water balance, calculated as annual precipitation minus potential evapotranspiration, was a single variable that could explain 81.7% of the variance in species richness. Our data suggest that the "water-energy dynamics" hypothesis can apply not only at the global scale but also at subcontinental scales of higher latitudes, as water availability was found to be the primary limiting factor also in this extratropical region with summer-warm and dry climate. A narrow zone with a sharp south-to-north switch in the two main diversity constraints seems to constitute the dominant and general pattern of terrestrial diversity across a large part of northern Eurasia, resulting in a subcontinental diversity hotspot of various taxa in this zone.

Department of Botany and Zoology Masaryk University Brno Czech Republic

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Rosenzweig ML (1995) Species diversity in space and time. Cambridge: Cambridge University Press. 436 p.

Willig MR, Kaufmann DM, Stevens RD (2003) Latitudinal gradients of biodiversity: pattern, process, scale and synthesis. Annu Rev Ecol Syst 34: 273–309.

Pimm SL, Brown JH (2004) Domains of diversity. Science 304: 831–833. PubMed

Nekola JC (2005) Latitudinal richness, evenness, and shell size gradients in eastern North American land snail communities. Rec West Aust Mus Suppl. 68: 39–51.

Bromham L, Cardillo M (2003) Testing the link between the latitudinal gradient in species richness and rates of molecular evolution. J Evol Biol 16: 200–207. PubMed

Hillebrand H (2004) On the generality of the latitudinal diversity gradient. Amer Nat 163: 192–211. PubMed

Cardillo M, Orme CDL, Owens IPF (2005) Testing for latitudinal bias in diversification rates: an example using New World birds. Ecology 86: 2278–2287.

Horsák M, Chytrý M, Axmanová I (2013) Exceptionally poor land snail fauna of central Yakutia (NE Russia): climatic and habitat determinants of species richness. Polar Biol 36: 185–191.

Francis AP, Currie DJ (2003) A globally consistent richness–climate relationship for angiosperms. Amer Nat 161: 523–536. PubMed

Field R, Hawkins BA, Cornell HV, Currie DJ, Diniz-Filho AJF, et al. (2009) Spatial species-richness gradients across scales: a meta-analysis. J Biogeogr 36: 132–147.

Hawkins BA, Porter EE, Diniz-Filho JAF (2003) Productivity and history as predictors of the latitudinal diversity gradient of terrestrial birds. Ecology 84: 1608–1623.

Davidowitz G, Rosenzweig ML (1998) The latitudinal gradient in species diversity among North American grasshoppers (Acrididae) within a single habitat: a test of the spatial heterogeneity hypothesis. J Biogeogr 25: 553–560.

Skillen EL, Pickering J, Sharkey MJ (2000) Species richness of the Campopleginae and Ichneumoninae (Hymenoptera: Ichneumonidae) along a latitudinal gradient in eastern North America old-growth forests. Environ Entomol 29: 460–466.

Chown SL, Gaston KJ, Williams PH (1998) Global patterns in species richness of pelagic seabirds: the Procellariiformes. Ecography 21: 342–350.

Janzen DH (1981) The peak in North American ichneumonid species richness lies between 38° and 42° North. Ecology 62: 532–537.

Bannister JR, Vidal OJ, Teneb E, Sandoval V (2012) Latitudinal patterns and regionalization of plant diversity along a 4270-km gradient in continental Chile. Austral Ecol 37: 500–509.

Currie DJ (1991) Energy and large-scale patterns of animal and plant-species richness. Amer Nat 137: 27–49.

Mittelbach GG, Steiner CF, Scheiner SM, Gross KL, Reynolds HL, et al. (2001) What is the observed relationship between species richness and productivity? Ecology 82: 2381–2396.

Riddle WA (1983) Physiological ecology of snails and slugs. In: Russell-Hunter WD, editor. The Mollusca, Vol. 6: Ecology. London: Academic Press, 431–461.

Ansart A, Vernon P (2003) Cold hardiness in molluscs. Acta Oecol 24: 95–102.

von Humboldt A (1808) Ansichten der Natur, mit wissenschaftlichen Erläuterungen. Tübingen: J. G. Cotta, 474 p.

Cameron RAD, Greenwood JJD (1991) Some montane and forest molluscan faunas from eastern Scotland: effects of altitude, disturbance and isolation. In: Meier-Brook C, editor. Proceedings of the 10th International Malacological Congress. Tübingen: Unitas Malacologica, 437–442.

Horsák M, Cernohorsky N (2008) Mollusc diversity patterns in Central European fens: hotspots and conservation priorities. J Biogeogr 35: 1215–1225.

Schamp B, Horsák M, Hájek M (2010) Deterministic assembly of land snail communities according to species size and diet. J Anim Ecol 79: 803–810. PubMed

Ložek V (1964) Quartärmollusken der Tschechoslowakei. Praha: Nakladatelství Československé akademie věd. 374 p.

Martin K, Sommer M (2004) Relationships between land snail assemblage patterns and soil properties in temperate-humid forest ecosystems. J Biogeogr 31: 531–545.

O’Brien EM (1998) Water–energy dynamics, climate, and prediction of woody plant species richness: an interim general model. J Biogeogr 25: 379–398.

O’Brien EM, Whittaker RJ, Field R (1998) Climate and woody plant diversity in southern Africa: relationships at species, genus and family levels. Ecography 21: 495–509.

O’Brien EM (2006) Biological relativity to water–energy dynamics. J Biogeogr 33: 1868–1888.

Hawkins BA, Field R, Cornell HV, Currie DJ, Guegan JF, et al. (2003) Energy, water, and broad-scale geographic patterns of species richness. Ecology 84: 3105–3117.

Field R, O’Brien EM, Whittaker RJ (2005) Global models for predicting woody plant richness from climate: development and evaluation. Ecology 86: 2263–2277.

Walter H (1974) Die Vegetation Osteuropas, Nord- und Zentralasiens. Stuttgart: Gustav Fischer Verlag. 452 p.

Hijmans RJ, Cameron SE, Parra JL, Jones PG, Jarvis A (2005) Very high resolution interpolated climate surfaces for global land areas. Inter J Climatol 25: 1965–1978.

Horsák M (2003) How to sample mollusc communities in mires easily. Malacologica Bohemoslovaca 2: 11–14.

Pilsbry HA (1948) Land Mollusca of North America north of Mexico. Vol. II, part 2. Philadelphia: The Academy of Natural Sciences of Philadelphia. 1113 p.

Kerney MP, Cameron RAD, Jungbluth JH (1983) Die Landschnecken Nord- und Mitteleuropas. Hamburg/Berlin: Parey Verlag. 384 p.

Sysoev A, Schileyko A (2009) Land snails of Russia and adjacent countries. Sofia/Moscow: Pensoft. 312 p.

Horsák M, Juřičková L, Picka J (2013) Molluscs of the Czech and Slovak Republics. Zlín: Kabourek. 264 p.

Trabucco A, Zomer RJ, Bossio DA, van Straaten O, Verchot LV (2008) Climate change mitigation through afforestation/reforestation: A global analysis of hydrologic impacts with four case studies. Agricul Ecosyst Environ 126: 81–97.

Churkina G, Running SW, Schloss AL, the participants of the Potsdam NPP model intercomparison (1999) Comparing global models of terrestrial net primary productivity (NPP): the importance of water availability. Glob Change Biol 5 (Suppl. 1)46–55.

Juřičková L, Horsák M, Cameron R, Hylander K, Míkovcová A, et al. (2008) Land snail distribution patterns within a site: the role of different calcium sources. Eur J Soil Biol 44: 172–179.

Wäreborn I (1969) Land molluscs and their environments in an oligotrophic area in southern Sweden. Oikos 20: 461–479.

Zbíral J (1995) [Analysis of plant material. Unified techniques]. Brno: Central Institute for Supervising and Testing in Agriculture. 192 p. [In Czech].

Cook R D (1977) Detection of influential observation in linear regression. Technometrics 19: 15–18.

Cleveland WS (1979) Robust locally weighted regression and smoothing scatterplots. J Amer Stat Assoc 74: 829–836.

R Core Team (2012) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna- URL http://www.R-project.org/.

Buckley LB, Jetz W (2007) Environmental and historical constraints on global patterns of amphibian richness. Proc R Soc Lond B 274: 1167–1173. PubMed PMC

Malyshev LI (1993) Ecological background of the floristic diversity in northern Asia. Fragm Flor Geobot Suppl. 2(1): 331–342.

Rosenzweig ML (1992) Species diversity gradients: we know more and less than we thought. J Mammal 73: 715–730.

Nekola JC (2009) Big ranges from small packages: North American vertiginids more widespread than thought. The Tentacle 17: 26–27.

Cameron RAD, Pokryszko BM, Horsák M (2010) Land snail faunas in Polish forests: patterns of richness and composition in a post-glacial landscape. Malacologia 53: 77–134.

Ehlers J, Gibbard PL, editors (2004) Quaternary glaciations - extent and chronology, Part III: South America, Asia, Africa, Australasia, Antarctica. Amsterdam: Elsevier. 903 p.

Hausdorf B, Hennig C (2003) Nestedness of northwest European land snail ranges as a consequence of differential immigration from Pleistocene glacial refuges. Oecologia 135: 102–109. PubMed

Lennon JJ, Greenwood JJD, Turner JRG (2000) Bird diversity and environmental gradients in Britain: a test of the species–energy hypothesis. J Anim Ecol 69: 581–598.

Del Grosso S, Parton W, Stohlgren T, Zheng D, Bachelet D, et al. (2008) Global potential net primary production predicted from vegetation class, precipitation, and temperature. Ecology 89: 2117–2126. PubMed

Hylander K, Nilsson C, Jonsson BG, Göthner T (2005) Differences in habitat quality explain nestedness in a land snail metacommunity. Oikos 108: 351–361.

Horsák M (2006) Mollusc community patterns and species response curves along a mineral richness gradient: a case study in fens. J Biogeogr 33: 98–107.

IPCC (2007) Climate change 2007: The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge University Press. 582 p.

Willis KJ, Whittaker RJ (2002) Species diversity–scale matters. Science 295: 1245–1248. PubMed