Alpha, beta, or gamma: where does all the diversity go?
Alpha, beta, or gamma: where does all the diversity go?
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Alpha、Beta 或 Gamma：所有的多样性都去哪儿了？
DOI：
10.1017/s0094837300011969
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发表时间：
1988
期刊：
影响因子：
2.7
通讯作者：
SepkoskiJr,JJ
中科院分区：
文献类型：
--
作者：
SepkoskiJr,JJ
Global taxonomic richness is affected by variation in three components: within-community, or alpha, diversity; between-community, or beta, diversity; and between-region, or gamma, diversity. A data set consisting of 505 faunal lists distributed among 40 stratigraphic intervals and six environmental zones was used to investigate how variation in alpha and beta diversity influenced global diversity through the Paleozoic, and especially during the Ordovician radiations. As first shown by Bambach (1977), alpha diversity increased by 50 to 70 percent in offshore marine environments during the Ordovician and then remained essentially constant for the remainder of the Paleozoic. The increase is insufficient, however, to account for the 300 percent rise observed in global generic diversity. It is shown that beta diversity among level, soft-bottom communities also increased significantly during the early Paleozoic. This change is related to enhanced habitat selection, and presumably increased overall specialization, among diversifying taxa during the Ordovician radiations. Combined with alpha diversity, the measured change in beta diversity still accounts for only about half of the increase in global diversity. Other sources of increase are probably not related to variation in gamma diversity but rather to appearance and/or expansion of organic reefs, hardground communities, bryozoan thickets, and crinoid gardens during the Ordovician.
