Ecoclimatological Survey of the Wetland Biota in the Tropical Wet-and-Dry Climatic Zone

The distinctness of the conditions in the water bodies of the tropical wet-and-dry climatic zone is demonstrated by a survey of the adaptations employed by the plant and animal species to survive the seasons unfavourable to their activity. The species filling common niches in the water bodies of this zone on different continents are compared. Unmistakable phylogenetic relationships among the species filling common niches in various parts of the world can be recognized. Through comparisons of the activity and distribution of 104 species, the adaptations of the biota to the seasonal changes were found to be generally similar to those of the biota in the temperate zones in that both must produce dormant stages during the same months each year. The inherent instability of the aquatic ecosystem encourages the development of very fast growing organisms with high rates of recruitment and very unstable but resilient populations. As a consequence of their characteristic population dynamics, the impact of intercontinental introductions of aquatic species inhabiting this zone are found to be more likely to cause severe biotic disturbances than similar introductions of species adapted to other climatic zones.