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.
