Centres of plant endemism in China: places for survival or for speciation?

Abstract

Aim This study aimed to identify the 'centres of endemism' of the Chinese spermatophyte flora in order to indirectly detect the locations of past glacial refugia. The role of these areas as places for plant survival ('plant museums') and/ or areas for plant evolution and speciation ('plant cradles') was also assessed.Location China.Methods Distribution patterns of 555 plant endemic taxa, taken as a representative sample of the Chinese endemic flora, were mapped on a 1°· 1°l atitude/longitude grid. For each grid cell, species richness (total count of species) and weighted richness (down-weighting each species by the inverse of its range) were calculated. Grid cells within the top 5% of highest values of weighted richness were considered centres of endemism. Based on available information, all plant taxa included in this study were classified into palaeoendemics and neoendemics, and their distributional patterns were represented separately.

Linajes de angiospermas endémicas en México: zonas de alto endemismo para la conservación

“…For other areas with high degrees of endemism, such as the Andes, isolation caused diversification, similar in many respects to the floras of remote oceanic islands (Särkinem et al, in press) or along elevational gradients (Kessler, 2000). Climate was the factor that promoted speciation in Australia's areas of endemism (Ladiges et al, 2011), while tectonic stability in central and southern China influenced the permanence of areas of plant endemism (López-Pujol et al, 2011). In Sub-Saharan Africa, elevation range and low seasonality were core environmental predictors for centers of endemism (Jetz et al, 2004).…”

Conservation of Chinese Plant Diversity: An Overview

“…2), Glyptostrobus, Keteleeria, Metasequoia (Fig. 2) Most of these plant refugia generally also served as areas for plant evolution and speciation ('plant cradles') in addition to being places for their persistence during the Neogene cooling (Axelrod et al, 1996;López-Pujol et al, 2011). Interestingly, the main centres of evolution were located in the southwestern part of China, that is, the eastern fringe of the Tibetan Plateau.…”

“…Huang et al, 2010) due to their low suitability (too steep). However, other practices such as extensive logging and overgrazing have significantly damaged the natural ecosystems of these areas (CI, 2007;Morell, 2008 Ying et al, 1993;Wang & Zhang, 1994;Ying, 2001;Li et al, 2003;Tang et al, 2006;Zhang & Ma, 2008;Li et al, 2009;López-Pujol et al, 2011). The code numbers for the different hotspots correspond to those in Fig.…”

“…This wealth of species diversity and endemism is attributable to a series of factors largely related to the biogeography, tectonics and geological history of the country, including: (i) a complex and extended geological history, with many tectonic events, (ii) a large proportion of the area of China within tropical and subtropical latitudes, (iii) the wide and persistent connection of China to tropical regions of Southeast Asia as well as with other regions, (iv) an unbroken connectivity between tropical, subtropical, temperate, and boreal forests, (v) a highly rugged and dissected topography (especially in southern China), and (vi) perhaps the most significant, reduced extinction rates during the late Cenozoic global cooling (e.g. Tiffney, 1985;Latham & Ricklefs, 1993;Axelrod et al, 1996;Guo et al, 1998;Guo, 1999;Qian & Ricklefs, 1999;Qian, 2001Qian, , 2002Ying, 2001;López-Pujol et al, 2006, 2011Qian et al, 2006;Wu et al, 2007;Li, 2008 One of the main features of Chinese vascular flora is its ancient origin; the modern flora of China is still showing a strong relictual character (Thorne, 1999;Qian & Ricklefs, 1999;Qian, 2001;López-Pujol & Ren, 2010;López-Pujol et al, 2011). This is directly linked to the geologic history of China's landmass, with some of the events influencing the flora composition tracing back to the early Mesozoic.…”

“…15 Ma; Zachos et al, 2001) onwards, a progressive global cooling produced numerous plant extinctions in most of the Northern Hemisphere, especially Europe and North America (Tiffney, 1985;Sauer, 1988;Axelrod et al, 1996;Jackson & Weng, 1999), and these were centered on the relictual, thermophilic elements of the 'boreotropical flora' (Tiffney, 1985;Latham & Ricklefs, 1993). In contrast, the limited ice coverage in East Asia during the Quaternary glaciations (significantly milder than in Europe and North America, and limited only to northern areas north of 60º N; Qian & Ricklefs 1999), coupled with the numerous mountain ranges in the southern section of China (which would have provided long-term stable habitats through local buffering of the extreme climatic oscillations) and the lack of barriers for southwards migration enabled the country to serve as a refuge for many Tertiary plant lineages, ensuring their survival to the present day (Axelrod et al, 1996;Qian & Ricklefs, 2000;López-Pujol et al, 2011). The presence of numerous and extensive refugia is likely to be the cause of the overrepresentation of relict elements in the modern flora of China and the much larger overall taxonomical richness of the Asian country with respect to other territories from the Northern Hemisphere (Europe and the United States, with comparable areas, harbor a much poorer flora: 11,500 and 18,000 species, respectively; Axelrod et al, 1996).…”