Biodiversity in Aquatic Systems and Environments: Lake Biwa

99 Pages·2014·1.91 MB·English

by  Noboru Okuda

SPRINGER BRIEFS IN BIOLOGY
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Kayoko Fukumori · Shin-ichi Nakano
Takefumi Nakazawa
Biodiversity
in Aquatic
Systems and
Environments
Lake Biwa
123
SpringerBriefs in Biology
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Noboru Okuda (cid:129) Katsutoshi Watanabe
Kayoko Fukumori (cid:129) Shin-ichi Nakano
Takefumi Nakazawa
Biodiversity in Aquatic
Systems and Environments
Lake Biwa
Noboru Okuda Katsutoshi Watanabe
Center for Ecological Research Department of Zoology
Kyoto University Graduate School of Science
Otsu, Japan Kyoto University
Kyoto , Japan
Kayoko Fukumori
Section of Integrative Biology Shin-ichi Nakano
The University of Texas at Austin Center for Ecological Research
Austin , TX , USA Kyoto University
Otsu, Japan
Takefumi Nakazawa
Department of Life Sciences
The College of Biosciences
and Biotechnology
National Cheng Kung University
Tainan , Taiwan
ISSN 2192-2179 ISSN 2192-2187 (electronic)
ISBN 978-4-431-54149-3 ISBN 978-4-431-54150-9 (eBook)
DOI 10.1007/978-4-431-54150-9
Springer Tokyo Heidelberg New York Dordrecht London
Library of Congress Control Number: 2013951142
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Foreword
While the twentieth century was the century when researchers tried to discover “the
general basic principles of organisms,” the twenty-fi rst century is expected to be the
century when researchers try to understand “the evolution and diversity of organ-
isms” on the basis of such general principles of organisms by integrating various
disciplines such as morphology, physiology, and ecology.
The chief diffi culty in studying “the evolution and diversity of organisms” lies in
the fact that we have to consider factors at various levels ranging from the genome
to the ecosystem. As taking various factors into account may cause a loss of focus,
traditional studies have been restricted to analyzing only one individual level or fac-
tor. However, unfortunately, the current research and education system based on
such a compartmentalized approach is inadequate for incisively studying “the evo-
lution and diversity of organisms.”
In order to solve these problems, we should strongly emphasize the necessity for
joint studies and integration of the education programs between micro-level biology
(genomic science, evolutionary developmental biology, genetic science, cell biol-
ogy, neurobiology, molecular physiology, and molecular evolutionary studies) and
macro-level biology (primatology, anthropology, ethology, environmental biology,
evolutionary taxonomy, and so on) to young biologists. We launched a new educa-
tion program in Kyoto University, called “Global COE program for Evolution and
Biodiversity Research” to promote such integrative studies at various levels, and
have succeeded in initiating novel currents of study of biodiversity that led rather
than followed those in the rest of the world. To this aim, we decided to publish six
books in “SpringerBriefs in Biology” which we hope will stimulate interest in such
novel approaches on the evolution and diversity of organisms in the world and
among young biologists.
This book covers a broad range of aquatic biology from molecular biology,
through ecology, to paleobiology in Lake Biwa, a fascinating ancient lake that is
also famed as a biodiversity hotspot. It will be a useful resource not only for
researchers and technicians but also for graduate students who want to learn aquatic
science. Naturalists and nature lovers can enjoy here a virtual tour of the world of
biodiversity in this ancient lake. That biodiversity ranges over vast differences of
v
vi Foreword
scale: We describe the latest molecular genetics techniques that have revealed a
relationship between the lake’s microbial diversity and its ecosystem functioning.
We also describe the evolutionary history of the lake’s biodiversity, especially fi sh
diversity, as well as laboratory experiments that revealed that diversity of fi sh feed-
ing morphology affects the body size of plankton communities and consequently
the overall ecosystem properties.
Unfortunately, Lake Biwa is also known as a tragic lake which has suffered from
a variety of human disturbances, such as eutrophication, habitat destruction, exotic
species introduction, and global warming, and that is now threatened by biodiver-
sity loss and ecosystem deterioration. This book thus will appeal to conservationists
and policy makers who are interested in biodiversity conservation and ecosystem
management. As well, it will provide an opportunity for all readers to think deeply
about the need to conserve the earth’s biodiversity.
Kiyokazu Agata
Professor, Department of Biophysics, Kyoto University
Project Leader of Kyoto University Global COE program
“Evolution and Biodiversity”
Pref ace
Two decades have passed since the Earth Summit, at which the Convention on
Biological Diversity (CBD) came into force to encourage the conservation of bio-
logical diversity on the earth and the fair and equitable sharing of benefi ts arising
from the sustainable use of its components. At present, the loss of biological diver-
sity has progressed at an accelerating rate and is particularly severe in freshwater
ecosystems, in which environmental alterations have been extreme due to drastic
changes in land-use patterns. For most of us, it is intuitively understandable why
fi shery resources should be conserved, because they provide humankind with ben-
efi ts such as food sources, i.e., a provisioning service from aquatic ecosystems.
However, it is not so easy to answer the question of why fi sh diversity is necessary
for human well-being. We also have little knowledge on how diversity of other
aquatic biota, especially of microbes, affects ecosystem properties such as organic
production, water purifi cation, and nutrient cycling. Or rather, we human beings
have no inherent sense to discern the invisible nature of diversity in a microscopic
world. For aquatic biologists, therefore, it is a great challenge to perceive the entity
of biological diversity in aquatic ecosystems, trace its evolutionary history, and dis-
cover the ecological consequences of its evolutionary diversifi cation, toward the
integration of biodiversity sciences.
Here we introduce the latest topics of ecological and evolutionary research on
aquatic biological diversity from bacteria to fi shes, with special reference to the case
of Lake Biwa. Lake Biwa, in western Japan, is an ancient lake with a geological
history of four million years, making it the third oldest lake in the world. It is called
a biodiversity hotspot, where 1,769 aquatic species including 61 endemics are
recorded, providing a rare opportunity to study the evolutionary diversifi cation of
aquatic biota and its ecological consequences. In this book, we fi rst narrate the evo-
lutionary history of biological diversity, especially of fi sh diversity in this lake,
focusing on its paleogeography and molecular phylogeny (Chap. 1 by Katsutoshi
Watanabe). The reader will learn how physical features of the lake have promoted
evolutionary diversifi cation of feeding functions in fi shes.
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viii Preface
Functional diversifi cation of fi shes, which play important ecological roles as
keystone predators of lake ecosystems, can sometimes be a major driver for altering
an entire lake community through their top-down trophic cascading effects (Chap. 2
by Noboru Okuda and Kayoko Fukumori). We demonstrate that predator functional
diversity has the potential for altering species composition, size structure, and tro-
phic relations of an entire biological community, which in turn affects ecosystem
functioning such as energy fl ows and nutrient cycling.
In lakes, the leading actors in ecosystem functioning, such as production and
mineralization of organic matter, are microbes, which are often regarded as ecosys-
tem engineers altering aquatic environments because of their overwhelming domi-
nance in number and mass. A few decades ago, the diversity of aquatic microbes in
nature remained unexplored because a large portion of bacteria never grow under
cultivation to be isolated for taxonomic identifi cation. However, the recent explo-
sion of advances in molecular techniques has vigorously encouraged microbiolo-
gists to characterize genetic and functional diversity of in situ microbial communities
(Chap. 3 by Shin-ichi Nakano).
While respecting the blessings of invaluable biological diversity in lake ecosys-
tems, we have to warn that modern human activities have brought a crisis of biodi-
versity loss in lakes worldwide, which will result in deterioration of ecosystem
functioning and thus of ecosystem services. In the face of such human disturbances,
ecosystem alterations are often catastrophic, a phenomenon known as ecological
regime shift. To understand how human-mediated environmental changes can
induce regime shifts in lake ecosystems and to evaluate how their biological diver-
sity, especially intraspecifi c phenotypic diversity, affects ecosystem resilience, i.e.,
dampening the incidence and intensity of regime shifts, a promising approach is
construction of theoretical models, which is considered a kind of thought experi-
ment to test probable future scenarios (Chap. 4 by Takefumi Nakazawa).
Again, we stress that Lake Biwa can be an ideal model system in which to prac-
tice biodiversity conservation with the promotion of ecological and evolutionary
understanding of biological diversity in lake ecosystems. This opportunity exists
because Lake Biwa has experienced a variety of serious environmental problems
that are shared by many other lakes worldwide, and also because the lake currently
shows symptoms of recovery from the biodiversity loss and ecosystem deteriora-
tion, recognized only by our persistent efforts in biodiversity research. Through this
book, the reader will learn how the evolutionary diversifi cation of aquatic organ-
isms interplays with the ecology of their populations and communities, and vice
versa, and why we should conserve biological diversity at different levels of bio-
logical organization from genes to ecosystems.
Otsu , Japan N oboru Okuda
Contents
1 Origin and Diversification of Freshwater Fishes in Lake Biwa .............. 1
1.1 Introduction: Lake Biwa and Its Fish Fauna ........................................ 1
1.2 A Brief Review on the Origins and Evolution
of Freshwater Fishes ............................................................................ 8
1.3 Molecular Phylogenetic Approaches ................................................... 10
1.3.1 Origin of Endemic Lineages .................................................... 10
1.3.2 Population Establishment by Endemic
and Non-endemic Species ........................................................ 14
1.4 Conclusions and Perspectives .............................................................. 15
References ..................................................................................................... 17
2 Predator Diversity Changes the World: From Gene to Ecosystem ........ 21
2.1 Why is Biodiversity Important? ........................................................... 21
2.2 Biodiversity at Three Levels ................................................................ 22
2.3 What is Phenotypic Polymorphism? .................................................... 22
2.4 Phenotypic Polymorphism in Aquatic Ecosystems ............................. 23
2.4.1 Trophic Polymorphism and Adaptive Divergence ................... 23
2.4.2 Ecological Speciation and Species Pair ................................... 25
2.4.3 The Ancient Lake Biwa as an Evolutionary Hot Spot ............. 26
2.4.4 Life History Polymorphism ..................................................... 27
2.4.5 Rapid Evolution of Trophic Polymorphism ............................. 28
2.4.6 Genetic Mechanisms of Trophic Polymorphism ..................... 30
2.5 Niche Construction .............................................................................. 31
2.6 Predator Diversity and Ecosystem Functioning ................................... 33
2.6.1 Mesocosm Experiments ........................................................... 35
2.6.2 Food Web Properties as a Universal Measure ......................... 37
2.7 Eco-Evolutionary Feedbacks ............................................................... 40
2.7.1 Feedback Loops ....................................................................... 41
2.7.2 Community Genomic Dynamics ............................................. 43
2.8 Why is Predator Diversity Important? ................................................. 44
References ..................................................................................................... 45
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