PARENT SESSION
Contributed Oral Session 92: Biodiversity: Aquatic Systems
Wednesday, August 10, 1:30 PM - 5:00 PM, Meeting Room 513 C, Level 5, Palais des congrès de Montréal

Ecology, history, and the distribution of fish species in Ontario lakes.

Gardezi, Tariq¹, ¹ McGill University, Montreal, Quebec, Canada

ABSTRACT- Species' distributions may be viewed as the product of three general classes of phenomenon: historical processes, chance, and the adaptations of species for particular environmental conditions. The relative importance of these factors may differ with spatial scale. In this study, records of fish species occurrence from approximately 8,000 sites (lakes) as well as many environmental variables are used to assess the relative importance of environment and regional history for determining where fish species occur. Results indicate that environmental variables and the history of the region both account for a significant amount of variation in species occurrence at this scale (approximately 900,000 square kilometers). However, neither factor accounts for very much of this variation (together, less than 20%). Most of this variation is shared between the two factors, suggesting that environmental and historical gradients tend to overlap. Results are interpreted in terms of the trade-off in conducting biological surveys between the extent of the survey and grain at which species and environmental variables must be sampled; and in terms of their significance for neutral ecological models for patterns of distribution and abundance.

Key words: fish species occurrence, biological survey, regional history, adaptation