Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Taxonomic Diversity of Island Biotas

Daniel S. Simberloff
Evolution
Vol. 24, No. 1 (Mar., 1970), pp. 23-47
DOI: 10.2307/2406712
Stable URL: http://www.jstor.org/stable/2406712
Page Count: 25
  • Read Online (Free)
  • Download ($4.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Taxonomic Diversity of Island Biotas
Preview not available

Abstract

1) For any taxon higher than genus, the expected mean number of species per genus (E(S/G)) for a randomly drawn subset is a non-decreasing function (approximately linear for many taxa) of the size of the subset, and is therefore lower than the mean number of species per genus for the entire taxon. 2) The relationship of actual S/G for an island biota to S/G expected for a random subset of identical size drawn from the species pool of the presumed source area is relatively insensitive to modifications of taxonomy and to use of a source area slightly larger than the real one. This relationship is subject to more drastic change upon use of incomplete species lists for island or source or a presumed source area smaller than or different from the real source. 3) Pseudo-random drawings of biotas of identical size to those of a number of islands show that, in general, the mean number of species per genus, though lower than in the source biota, is higher than would be expected on a hypothesis of random colonization. 4) The deviation of actual from expected S/G is not strongly correlated with island area, maximum elevation, and distance from source. 5) The claimed positive correlation between species range and genus size, even if it should be shown to exist, is probably insufficient to account for the magnitude of these deviations. 6) The main causes of the excess of insular S/G's over those predicted by chance are probably two simultaneous tendencies: a) similarity of congeneric species in ecological requirements. b) similarity of congeneric species in dispersal capabilities.

Page Thumbnails

  • Thumbnail: Page 
23
    23
  • Thumbnail: Page 
24
    24
  • Thumbnail: Page 
25
    25
  • Thumbnail: Page 
26
    26
  • Thumbnail: Page 
27
    27
  • Thumbnail: Page 
28
    28
  • Thumbnail: Page 
29
    29
  • Thumbnail: Page 
30
    30
  • Thumbnail: Page 
31
    31
  • Thumbnail: Page 
32
    32
  • Thumbnail: Page 
33
    33
  • Thumbnail: Page 
34
    34
  • Thumbnail: Page 
35
    35
  • Thumbnail: Page 
36
    36
  • Thumbnail: Page 
37
    37
  • Thumbnail: Page 
38
    38
  • Thumbnail: Page 
39
    39
  • Thumbnail: Page 
40
    40
  • Thumbnail: Page 
41
    41
  • Thumbnail: Page 
42
    42
  • Thumbnail: Page 
43
    43
  • Thumbnail: Page 
44
    44
  • Thumbnail: Page 
45
    45
  • Thumbnail: Page 
46
    46
  • Thumbnail: Page 
47
    47