PARENT SESSION
Symposium 5: Marine macroecology
Organized by: JD Witman and K Roy
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 517 B, Level 5, Palais des congrès de Montréal
Macroecological diversity patterns: A marine-terrestrial comparison.
Witman, Jon*,1, Etter, Ron2, Smith, Franz1, 1 Brown University, Providence, RI2 University of Massachusetts, Boston, MA
ABSTRACT- Although macroecological patterns in the ocean ultimately result from evolutionary history, oceanographic processes, species interactions and human activity, little is actually known about the general mechanistic processes driving the emerging patterns. We synthesize recent evidence for three macroecological patterns of species diversity in the ocean 1) local-regional diversity relationships, 2 productivity diversity relationships and 3) latitudinal diversity gradients and compare them to their better-studied terrestrial counterparts. In addition to informing fundamental differences, such a comparative approach could provide insight into general mechanisms transcending ecosystem boundaries. The results indicate that local diversity in both terrestrial and marine communities is predominantly positively and linearly related to regional diversity, implying that colonization from the regional species pool is an important driver of local species richness. The proportion of the regional species pool represented in local communities tends to be lower in marine than in terrestrial communities. The hypothesis that this results from limited dispersal from the regional pool to local communities will be evaluated along with several alternates. On a global scale, the relationship between productivity and diversity in the ocean is paradoxical when water column productivity is used as the independent variable as high levels of diversity occur in low productivity tropical waters. Like other macroecological relationships, the form of the productivity diversity function is scale -dependent and causality may be better informed by a multivariate approach that includes tropho-dynamic factors. While there is increasing evidence for a latitudinal diversity gradient in the oceans, decreasing from low to high latitudes as on land, it does not hold for all taxonomic groups, may be offset N or S from the equator, and asymmetric due to recent findings of high diversity in Antarctic waters.
Key words: local - regional diversity, productivity - diversity, latidudinal diversity gradients, epifauna