If you need an accessible version of this item please contact JSTOR User Support

Body Size, Aerial Dispersal, and Origin of the Pacific Land Snail Fauna

Joseph Vagvolgyi
Systematic Zoology
Vol. 24, No. 4 (Dec., 1975), pp. 465-488
DOI: 10.2307/2412906
Stable URL: http://www.jstor.org/stable/2412906
Page Count: 24
  • Download PDF
  • Cite this Item

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 need an accessible version of this item please contact JSTOR User Support
Body Size, Aerial Dispersal, and Origin of the Pacific Land Snail Fauna
Preview not available

Abstract

Minute genera, whose shell measures less than 100 mm, form 60.0% of the Pacific land snail fauna. In contrast to this, the minute class only represents 27.1% of the continental fauna. The mean generic size in the Pacific fauna is correspondingly lower: 11.9 mm vs. 20.6. The difference between the 2 groups is statistically highly significant. Similarly to the Pacific, the eastern Pacific and eastern Atlantic insular land snail faunas and the wide-spread fauna also are dominated by the minute genera. From these observations it is concluded that minute body size is advantageous for long distance dispersal, both overseas and overland, in the land snails. This in turn indicates that the mechanism involved must be aerial, since only in this type of dispersal are small size and light weight advantageous. The minute species also are, as a rule, more abundant than the large ones, which constitutes a further advantage. Support to the hypothesis is provided by the facts that land snarls have been recovered from the plumage of birds; that recently formed volcanic islands have been colonized predominantly by minute land snails, and that mineral particles considerably larger and heavier than the minute land snails have been collected at high altitudes by airplanes. Alternative hypotheses are considered and rejected on the grounds that their tenets are unproven, unnecessary or erroneous; however, it is emphasized that the relationship between body size and area size needs further analysis. The characteristics of insular land snail faunas are summarized as follows: predominance of minute genera; high frequency of primitive, orthurethran genera and families; resemblance to the fauna of the nearest continent; low degree of enclemism on the family level, increasingly higher, on the genus and species level, relatively recent origin, through aerial immigration.

Page Thumbnails

  • Thumbnail: Page 
465
    465
  • Thumbnail: Page 
466
    466
  • Thumbnail: Page 
467
    467
  • Thumbnail: Page 
468
    468
  • Thumbnail: Page 
469
    469
  • Thumbnail: Page 
470
    470
  • Thumbnail: Page 
471
    471
  • Thumbnail: Page 
472
    472
  • Thumbnail: Page 
473
    473
  • Thumbnail: Page 
474
    474
  • Thumbnail: Page 
475
    475
  • Thumbnail: Page 
476
    476
  • Thumbnail: Page 
477
    477
  • Thumbnail: Page 
478
    478
  • Thumbnail: Page 
479
    479
  • Thumbnail: Page 
480
    480
  • Thumbnail: Page 
481
    481
  • Thumbnail: Page 
482
    482
  • Thumbnail: Page 
483
    483
  • Thumbnail: Page 
484
    484
  • Thumbnail: Page 
485
    485
  • Thumbnail: Page 
486
    486
  • Thumbnail: Page 
487
    487
  • Thumbnail: Page 
488
    488