Homage to Lloyd: revisiting a pioneering biogeographical paper in The Naturalist

摘要

Following a long-standing tradition, Lewis Lloyd-Evans ("Lloyd") published his 1974 Presidential Address to the YNU in The Naturalist: "The biogeography of snails in Yorkshire" (Lloyd-Evans, 1975). It is a short but wide-ranging account, dealing withmany interesting records of land and freshwater molluscs in the county. It also includes a detailed account of his systematic sampling of tetrads (2km squares) within a single 10km square (Ordnance Survey 44:20, Penistone). Among other ways of analysinghis data, he examined the relationship between the size of area and the number of species to be found in it, extending beyond the square to the then known fauna of increasing areas within Yorkshire and to the whole of Great Britain. Included in his analysis is a graph (his Figure 6) showing the relationship between the number of species of land and freshwater molluscs and the logarithms of the areas concerned. This kind of quantitative examination, species/area relationships (SARs hereafter) has a longhistory, but he was almost certainly unaware that his was the first attempt to do so for molluscs within a single land mass. These SARs have played a significant part in the development of biogeographical ideas (Rosenzweig, 1995) but the next attempts to analyse such SARs for continental as opposed to island molluscs did not appear until the end of the 20th century (Nekola and Smith, 1999; Cameron, 2002).