Karyology of Lower Teleost Fishes (Clupeiformes, Taxonomy, Elopiformes, Phylogeny)

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1985 Karyology of Lower Teleost Fishes (Clupeiformes, Taxonomy, Elopiformes, Phylogeny). Albert John Doucette Jr Louisiana State University and Agricultural & Mechanical College

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Recommended Citation Doucette, Albert John Jr, "Karyology of Lower Teleost Fishes (Clupeiformes, Taxonomy, Elopiformes, Phylogeny)." (1985). LSU Historical Dissertations and Theses. 4048. https://digitalcommons.lsu.edu/gradschool_disstheses/4048

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Doucette, Albert John, Jr.

KARYOLOGY OF LOWER TELEOST FISHES

The Louisiana Slate University and Agricultural and Mechanical Col. Ph.D. 1985

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University Microfilms International

KARYOLOGY OF LOWER TELEOST FISHES

A Dissertation

Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy

The Department of Zoology and Physiology

ALBERT JOHN DOUCETTE, JR.

To my parents, Albert J. Doucette, Sr. and the late

Albertine Atlow Doucette, for instilling in me the desire to learn and an appreciation for an education and to my sisters, Margaret Doucette Davis and Alice Doucette Twillie for their encouragement and support through the years.

ii ACKNOWLEDGEMENTS

Special thanks are due my major professor,

Dr. J. Michael Fitzsimons, for his encouragement and

assistance during my studies at Louisiana State University.

Also, I would like to thank the other members of my doctoral

committee, Dr. Kenneth C. Corkum, Dr. Dudley D. Culley, Jr.,

Dr. John W. Fleeger, Dr. Walter J. Harman, and Dr. William

G. Henk for reading and commenting on this dissertation.

I thank the following people for helping collect the

specimens used in this research: G. Tommy Chandler, Wilton

DeLaune, J. Michael Fitzsimons, William F. Font, Brian

Hanks, Jeffrey W. Korth, LuAnn T. Korth, William

H. LeGrande, Carol L. Lear, Lorraine Madsen, R. Jan

F. Smith, Carol S. Stevens and Jonathan G. Stevens.

For assistance on many collecting trips and for hours

of scientific discussions in and out of academic settings, I

thank Jeffrey Korth.

Many thanks go to Dr. William H. LeGrande for in

struction and assistance in photographic and computer work

and also for many discussions on karyology. A portion of

the analytical section of this research was supported by NSF

Grant No. PRM-8206665 to Dr. LeGrande. I wish to thank all my friends for encouragement and support during this project and Carol Stevens for typing this dissertation.

This study would not have been possible without the support from the Board of Regents Graduate Fellowship

Program. In this regard, I would like to offer special thanks to Dr. William Arceneaux, Commissioner of Higher

Education, and Ms. Sharon Beard, Deputy Commissioner. TABLE OF CONTENTS

Page

DEDICATION...... ii

ACKNOWLEDGEMENTS ...... iii

TABLE OF CONTENTS...... V

LIST OF T A B L E S ...... vi

LIST OF F I G U R E S ...... vii

ABSTRACT ...... viii

INTRODUCTION ...... 1

MATERIALS AND METHODS ...... 5

Procedures ...... 5

Basis for comparing karyotypic differences . . . 20

RESULTS AND DISCUSSION...... 25

Species accounts...... 25

Potential use of karyology in the taxonomy of elopiform and clupeiform fishes .... 33

Evolution of chromosomes in elopiform and clupeiform fishes ...... 37

Karyology and the phylogeny of teleost fishes. . 38

GENERAL CONCLUSIONS ...... 45

LITERATURE CITED ...... 46

VITA ...... 53

v LIST OF TABLES

Table Page

1. Summary of karyotypic data for Megalops atlanticus, Elops saurus, Brevoortia patronus, B . smithi, B. tyrannus, B. smi thi x EU tyrannus, Dorosoma cepedianum, D. petenense, Harengula clupeola and Anchoa mitchilli ...... 29

2. Chromosome numbers in elopiform and clupeiform fishes ...... 35

vi LIST OF FIGURES

Figure Page

1. Chromosomal rearrangements in fishes...... 21

2. Karyotypes of Megalops atlanticus and El ops saurus ...... 26

3. Karyotypes of Brevoortia patronus, B. smithi, B» tyrannus and B^ smithi x B^ tyrannus .... 27

4. Karyotypes of Dorosoma cepedianum, D. petenense, Harengula clupeola and Anchoa mitchilli ...... 28

vii ABSTRACT

Karyotypes of nine species (Megalops atlanticus, Elops

saurus, Brevoortia patronus, B. smithi, B. tyrannus,

Dorosoma cepedianum, D . petenense, Harengula clupeola, and

Anchoa mitchi11i) and one hybrid (B^ smithi x B^ tyrannus)

of teleost fishes revealed diploid complements ranging from

28 to 50 chromosomes and comprised of uniarmed elements or

combinations of uniarmed and small and large biarmed elements. The occurrence of large metacentric-submeta- centric chromosomes was usually associated with a reduction

in total chromosome number suggesting fusion events in the evolution of karyotypes from ancestral complements with 48 to 52 acrocentrics. Information from karyotypes is used to characterize species, genera, and families and, where possible, these data are used in combination with published reports to reinterpret previously proposed phylogenetic classifications.

viii INTRODUCTION

Karyology is the study of chromosome number and morphology and is used to assess intra- and interspecific relationships of animals and plants. Chromosome studies, important tools in taxonomy, also have potential in estimat ing the phylogenies of living organisms (Simon, 1963;

Taylor, 1967; Ohno et al. 1968; Takagi and Sasaki, 1974;

LeGrande and Fitzsimons, 1976; Bickham and Baker, 1977;

King, 1977; Dingerkus, 1979; Baker, et al., 1982).

Nelson (1984) estimated that living fishes number approximately 22,000 extant species. Other authors have estimated from 17,000 to 30,000 species (Wheeler, 1975;

Lagler et al., 1977; Lee et al., 1980). Since only about six percent of all living fishes have been karyotyped, interpretations of karyology require confirmation from other data sources.

Karyotypes are used just as any other morphological in formation in fish systematics, such as scale counts or fin-ray counts. Few chromosome studies of fishes have dealt with an entire group (family, subfamily or tribe) of which the geologic history of the range and the morphologic features are well known. Some notable exceptions are the centrarchids (Roberts, 1964), salmonids (Nygren et al.,

1971), and goodeids (Uyeno et al., 1983). Complete or near

1 2

complete studies on large groups of fishes are important in

order to understand and evaluate better the systematic

significance of chromosomal variations.

The elopiforms (ten pounders, tarpons, and bonefishes)

and clupeiforms (herrings and anchovies) are regarded by

ichthyologists as potential basal groups in the evolution of

teleost fishes. Gosline (1971) regards the elopiforms,

clupeiforms, salmoniforms (salmon and trout),

osteoglossiforms (mormyrids and bony tongues), angui11iforms

(true eels), cypriniforms (minnows and suckers), and

notacanthiforms (halosaurs and spiny eels), as "lower

teleosts" and on or near a direct line in teleostean

phylogeny. Greenwood et al. (1966) place the elopiforms

along with notacanthiforms, anguilliforms, and possibly clupeiforms into the superorder Elopomorpha. However, they do not rule out the possibility that the clupeiforms have an

origin independent of the elopiforms, and they also suggest

that both groups, because of morphological features and type of larvae, are off the main course of teleostean evolution.

Greenwood et al. suggest that among living fishes the salmoniforms are likely the basal group which is more closely related to the ancestors of higher ray-finned fishes. The fishes which make up the basal teleostean groups according to Gosline and Greenwood et al. have been of considerable interest to systematic ichthyologists, who for several decades have debated their positions in the evolution of teleost fishes. The importance of this debate is put into perspective when it is considered that over 90 percent of all species of fishes are teleosts (Gosline,

1971; Greenwood et al., 1966; Nelson, 1984).

The orders Elopiformes and Clupeiformes include about four genera with 11 species and 68 genera with 331 species respectively (Nelson, 1984). In this study, two species of elopiforms, in separate genera, were karyotyped. The genera are Megalops, a marine genus whose members are distributed in the Indo-Pacific, Atlantic, and Gulf of Mexico, and

Elops, marine fishes found off the coasts of the Americas,

South Africa, and tropical Australia (Wheeler, 1975). Seven species and one hybrid also karyotyped in this study represent four genera in the order Clupeiformes:

Brevoortia, marine fishes of the western Atlantic and Gulf of Mexico (Fischer, 1978); Dorosoma, common fresh- and brackish- water fishes of the central United States, coastal Gulf of Mexico, eastern Mexico, Guatemala, and

Nicaragua (Miller, 1960); Harengula, marine fishes of the western Atlantic, Gulf of Mexico, and Caribbean (Fischer,

1978); and Anchoa, coastal marine fishes of the western

Atlantic and Gulf of Mexico (Wheeler, 1975). The present study is the first report of a karyotype for the genus Brevoortia and includes three of the four recognized species. The first karyotypes for the genera

Anchoa and Harengula and the second for the genus Megalops are also provided. Karyotypic data for Dorosoma and Elops, although previously published (Fitzsimons and Doucette,

1981; Doucette and Fitzsimons, 1982), are an integral part of my study of lower teleost karyology and are included here. Karyotypes of these fishes are used to characterize species and genera and, where possible, used in combination with published reports to reinterpret previously proposed phylogenies. MATERIALS AND METHODS

Procedures.— Fishes were collected from native populations usually by seining or cast netting. Once karyotyped,

the fishes were cataloged and placed into the permanent collection of fishes of the Louisiana State University

Museum of Zoology (LSUMZ).

Specimens examined include:

LSUMZ 4340, Fish No. D83-10:l-5, 7, 8, FL: St. Lucie

Co., Mosquito impoundment, 5.5 mi. S. of intersection of

Fla. Hwys. A1A and 656, near Round Island Park,

A. J. Doucette, Jr., 4 October 1983 for Megalops atlanticus;

2722, F80-15:l, LA: Lafourche Parish, Dock at LUMCON