Modeling fish species diversity in river networks

River basins across the world are shaped by local land topography and generally have a dendritic structure formed by convergence of river streams originating in a watershed until they end up in the main river. These river basins are also home to a plethora of aquatic lifeforms. Movement patterns of riverine biodiversity, especially fishes, are shaped by dendritic structure of river networks (see Figure 1) and habitat capacity of river basins. The ongoing river networks project at CASUS is specifically aimed at developing models to study the effects of dendritic network topology on fish biodiversity and thereby be able to predict biodiversity patterns across various river basins. Starting with an initial distribution of fish species on the river network, we explore how the biodiversity patterns, such as local species richness (LSR), in dendritic river networks evolve with time, under the assumption of species being equivalent on a per capita basis. Such neutral biodiversity models have been able to successfully explain a suite of biodiversity indices of plant and animal species across various ecological systems. In summary, the river project aims to bring together the neutral biodiversity theory and the framework of dispersal over networks to make predictions on biodiversity in riverine systems across the world. This would enable understanding the factors shaping present biodiversity and allow us to explore how climate change might affect future riverine biodiversity.