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| Wu, Q.-X. and G. M. Mueller. 1997. Biogeographic relationships between the macrofungi of temperate eastern Asia and eastern North America. Canadian Journal of Botany 75 (12): 2108-2116. |
Abstract Eastern North America and temperate eastern Asia reportedly share a relatively high number of taxa of macrofungi (mushrooms and relatives), including a number of taxa that have putative eastern North America - temperate eastern Asia disjunct distributions. These reports have been used to imply an affinity between the mycotas (fungal equivalent of flora and fauna) of the two regions. To date, however, this affinity has not been examined in detail. A comparison of north temperate macrofungal mycotas was undertaken to examine the similarity between these regions. We used two methods in this study: 1) direct comparison of taxon lists and 2) calculation of the Simpson Coefficient of similarity from lists of selected taxa. These analyses were based on field work, herbarium records, and published taxonomic treatments for Amanita, Lactarius, Ramaria, and Boletaceae. Results of these analyses document that taxonomic similarity between eastern North America and temperate eastern Asia mycotas can be quite high. In all cases, the calculated similarity values for eastern North America - temperate eastern Asia comparisons are higher than those between either region of North America and Europe or between western North America and eastern Asia. Furthermore, the eastern North American and temperate eastern Asian disjunct distributions of macrofungi are usually limited to the level of species or lower. A list of disjunct species and the Simpson Coefficient values calculated among north temperate regions for Amanita, Lactarius, Ramaria, and Boletaceae are presented below, along with a References list. These are excerpts from the paper cited above. In addition, two disjunct species, Lactarius indigo and Suillus spraguei, are discussed. |
* HMAS: Specimens available from the Herbarium of Mycology, Academia Sinica |
Simpson Coefficient The Simpson Coefficient is a binary similarity coefficient proposed by Simpson (1960) to measure biotic resemblances between geographic areas. The Simpson Coefficient value is: C / N1 x 100 Where C is the number of taxa common to the two samples, and N1 is the total number of taxa (at the same taxonomic level) present in the smaller of the samples (smaller in terms of number of taxa). This coefficient reduces the effect of differences in size between the two samples and is therefore widely used in biotic comparisons (Flynn, 1986). In mycogeographic studies, this is especially important because it is unclear how much of the observed sample size difference between two regions is due to lack of sufficient collecting in the areas. In this paper we apply the Simpson Coefficient to data on several relatively well-studied groups of macrofungi that occur in each of the four regions in the north temperate zone. |
Amanita Species Distribution of Amanita in North Temperate Regions
Simpson Coefficient values calculated between eastern North America and western North America (i.e., 54), and between Europe and eastern Asia (i.e., 57) are higher than any other combinations. The lowest value (i.e., 29) was encountered in comparisons between western North America and Europe. While eastern North America and temperate eastern Asia share more taxa than any other pairs of regions, the coefficient of similarity is only 40. |
Lactarius Species Distribution of Lactarius in North Temperate Regions
About 200 species of Lactarius have been reported from North America (Hesler & Smith, 1979) and 80 taxa have been reported from temperate east Asia. Fourteen of these species show the eastern Asian-eastern North American disjunct distribution pattern, i.e., 8.7% of eastern North American species. As in Amanita, the eastern Asian locations of these species are mostly in southern and southwestern China, i.e., Guizhou, Sichuan, Yunnan, Xizang, Guangxi, and Fujian provinces. In both eastern Asia and North America, more Lactarius species are associated with deciduous trees (e.g., Quercus, Fagus) than with conifers (e.g., Pinus, Tsuga). The disjunct species Lactarius atroviridis, L. gerardii and L. indigo, also occur in Colombia and Costa Rica where they are associated with Quercus (Methven and Mueller, 1992; Mueller and Halling, 1995). The similarity value calculated between eastern North America and eastern Asia (i.e., 53) is close to that calculated between eastern North America and western North America (i.e., 49) and that for Europe and eastern Asia comparisons (i.e., 55). It is higher than the values calculated between eastern and western North America and Europe (i.e., 30 and 40) or between western North America and eastern Asia (i.e., 28). |
Ramaria Species Distribution of Ramaria in North Temperate Regions
The genus Ramaria is cosmopolitan, except for one section of Subgenus Echinoramaria which is pantropical. However, geographical ranges of species are limited and exhibit various biogeographic patterns (Corner, 1950, 1966, 1970; Marr & Stuntz, 1973; Petersen, 1975, 1981, 1984, 1986, 1987, 1988, 1989; Petersen & Zang, 1989, 1990; Wu, 1986). Of the 182 species known to the Northern Hemisphere, only 19 species (10%) are distributed throughout Asia, Europe and North America, and morphological varieties are often recognized within the widely distributed species. Of the 79 species reported from eastern Asia, 34 species (i.e., 43%) also occur in eastern North America. Twenty-eight of these are also found in either Europe or western North America. Five species of Ramaria, i.e., 8.6% of eastern North American species, seem confined to eastern North America and eastern Asia. Many Ramaria species are known only from one of the four regions defined in this study. Among the 76 species known from western North America, 29 species (i.e., 38%) have not been reported from any other area of the world. This level of endemism is similar to that seen in Europe, eastern Asia and eastern North America. The calculated similarity value between eastern North America and eastern Asia for Ramaria (i.e., 59) is higher than that calculated between all other combinations of regions. Values for eastern North America and western North America comparisons (i.e., 52) were the next highest followed by those calculated between Europe and eastern Asia (i.e., 43) and then Europe and North America (i.e., 37, 38). |
Boletaceae Species Distribution of Boletaceae in North Temperate Regions
Taxonomic summaries of Boletaceae are numerous (e.g., Alessio, 1985; Coker & Beers, 1943; Horak, 1987a, b; Moser, 1983; Singer, 1977; Singer, Garcia & Gómez, 1990, 1991, 1992; Smith & Thiers, 1971; Thiers, 1976, 1979; Wolfe 1979; Wolfe & Bougher, 1993; Zang, 1983, 1985, 1986, 1987, 1992; Zang & Chen, 1990). Boletaceae display a comparatively high level of endemism in all four northern temperate regions, ranging from 30% to 50%. Eastern North America is rich in species diversity of Boletaceae and it shares a relatively large number of species with eastern Asia. Europe and western North America share the least number of species. The relatively high numbers of shared species between eastern and western North America is largely influenced by the Florida - Texas distribution pattern as 35% of the shared species are reported from these two areas. Thirty-two species of Boletaceae, i.e., 12% of eastern North American species, seem confined to eastern North America and eastern Asia. The calculated similarity value between eastern North America and western North America is high (i.e., 64). Eastern North America and eastern Asia also have a relatively high coefficient of similarity (i.e., 51) and the two regions share 83 species. This value is slightly higher than that calculated between Europe and eastern Asia (i.e., 49), and is higher than the values calculated between Europe and North America (i.e., 28, 33), and between western North America and eastern Asia (i.e., 38). |
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