This book presents the latest topics in ecological and evolutionary research on aquatic
biodiversity from bacteria to fishes with special reference to Lake Biwa an ancient lake in
western Japan. With a geological history of 4 million years Lake Biwa is the third oldest lake
in the world. It is considered a biodiversity hotspot where 1 769 aquatic species including 61
endemics are recorded providing a rare opportunity to study the evolutionary diversification
of aquatic biota and its ecological consequences. The first chapter introduces the evolutionary
history of biodiversity especially of fish in this lake. In the second chapter some examples
of trophic polymorphism in fish are described. Fish are keystone predators in lake ecosystems
and they can be a major driver for altering biological communities through their top-down
trophic cascading effects. An excellent laboratory experiment is presented demonstrating that
functional diversity of fish feeding morphology alters food web properties of plankton prey
communities. The third chapter focuses on aquatic microbes whose abundance and diversity may
also be influenced by the diversity of fish through top-down trophic cascades. Aquatic microbes
can have a strong impact on ecosystem functioning in lakes and in this chapter the latest
molecular techniques used to examine genetic and functional diversity of microbial communities
are introduced. The final chapter presents theoretical frameworks for predicting how
biodiversity has the potential to control the incidence and intensity of human-induced regime
shifts. While respecting the precious nature of biodiversity in lakes it is essential to be
aware that modern human activities have brought a crisis of biodiversity loss in lakes
worldwide. Throughout this book readers will learn why biodiversity must be conserved at all
levels from genes to ecosystems.
