THE SYSTEMATIC STATUS OF FUNDULUS KANSAE
AND FUNDULUS ZEBRINUS
by
CHARLES THOMAS EVERETT, B.S. in Ed.
A THESIS
IN
ZOOLOGY
Submitted to the Graduate Faculty of Texas Tech University in
Partial Fulfillment of the Requirements for
the Degree of
MASTER OF SCIENCE
Approved
August, 1972
ACKNOWLEDGEMENTS
8QJ> f^tf^/oi"^
m Jin I am deeply grateful to my major advisor, Dr. John S.
Mecham, for his direction of this thesis. I am thankful
to Drs. Francis L. Rose and Robert W. Mitchell for the time
and equipment they provided. I sincerely thank Mr. Mike
Bishop, Mr. Scott Simpson, Mr. Greg Mengden, Mr. Tony
Mollhagen, and especially my wife, Donna, for their assis
tance in collecting the fish of this study. I am grateful
to Dr. Joe R. Goodin and, again. Dr. Francis L. Rose for
their constructive criticism of this manuscript. This
research was supported in part by National Science Founda
tion Grant {GB-13791) under the direction of Dr. John S.
Mecham.
11
CONTENTS
ACKNOWLEDGEMENTS ii
LIST OF TABLES iv
LIST OF FIGURES v
I. INTRODUCTION 1
II. METHODS AND MATERIALS 3
III. RESULTS 10
Morphological Analysis 10
Electrophoretic Analysis 12
IV. DISCUSSION 32
V. SUriMARY 3 9
LITERATURE CITED 41
111
LIST OF TABLES
Table Page
1. Analysis of Variance, Single Classification Males v.s. Females 25
2. Regression of Morphological Characters on Distance from Southernmost Locality 26
3. Descriptive Statistics for Pectoral Rays, Dorsal Rays and Vertical Bar Number-Males 28
4. Descriptive Statistics for Anal Rays and Principal Caudal Rays 30
5. Degree of Correlation between Scale Number and Vertebral Number 31
IV
LIST OF FIGURES
Figure Page
1. Sample Localities for Fundulus zebrinus 16
2. Typical Male and Female F. zebrinus 18
3. Descriptive Representation of Lateral Scale Number with Respect to Locality 20
4. Variation in Eye Diameter with Respect to Locality 22
5. Electrophoretic Pattern Differences between F. zebrinus and Cyprinodon rubrofluviatills 24
V
CHAPTER I
INTRODUCTION
According to the current literature there are two spe
cies of the genus Fundulus in the saline, alkaline waters
associated with the upper regions of the Central Plains
drainage systems. These two fish, F. zebrinus Jordan and
Gilbert and F. kansae Garman, exhibit morphological charac
ters not observed elsewhere in the genus. These include a
lengthy convoluted gut and weak, slender pharyngial teeth.
Two characters have been utilized in differentiating
the two fish. The first character, lateral scale number,
is found in many recognized keys (Blair, et al., 1968; Eddy,
1969; Knapp, 1953). In F. kansae the lateral series number
is given as 52 to 64 scales while in F. zebrinus the scale
count varies from 41 to 49. The other character, eye diam
eter, has been only infrequently mentioned (C. L. Hubbs,
1926; Koster, 1957). Hubbs simply reported that F. zebrinus
had a larger eye. Koster compared the eye diameter to the
width of the preorbital bone. In F. kansae the width of the
preorbital was reported as being two-thirds or more of the
diameter of the eye while in F_. zebrinus the bone width is
no greater than one-half to two-thirds the diameter of the
eye. According to Koster, the preorbital size is essen
tially the same size in both species.
There has been some disagreement as to the ranges of
the two fish, but the concensus of most contemporary workers
is that F. kansae is found from South Dakota to northern
Texas and eastern New Mexico, or more generally the Arkansas
River basin east to Missouri; F. zebrinus is found in the
Brazos, Colorado, and Pecos River drainages of Texas and New
Mexico.
Several authors (Miller, 1955; Metcalf, 1966; Pfliger,
1971) have suggested the possibility of conspecificity be
tween F. kansae and F. zebrinus but have lacked sufficient
evidence to support this contention. This study was under
taken with the objective of determining the systematic
relationships of the two animals.
CHAPTER II
METHODS AND MATERIALS
Specimens for analysis were collected at the 20 local
ities indicated in Figure 1. These localities were dis
tributed from the lower portion of the Pecos drainage in
southwestern Texas northward to the Smokie Hill River in
the west-central portion of Kansas (least distance approxi
mately 573 miles). Eight distinct drainages were sampled,
these being from north to south; Smokie Hill River, Arkansas
River, Cimarron River, Canadian River, Red River, Brazos
River, Colorado River, and Pecos River. Samples from numer
ous localities within the Canadian, Red and Brazos River
drainages were studied in order that the supposed range
limits of the fish could be closely inspected.
All fish were collected with a fine mesh, 20 foot seine.
The fish were most generally found in the stream bed proper
where the water was shallow with a moderate rate of flow, or
in the side pools adjoining the main body of water. The
fish definitely seemed to prefer a substrate of sand or fine
gravel.
The fish were kept in styrofoam containers for transpor
tation to the laboratory. Upon arrival in the laboratory a
random sample of the fish were preserved in 10% formalin;
the remaining fish were kept in aquaria, styrofoam coolers,
and large plastic containers. All fish were kept in an
3
environmental room with the water temperature stabilized at
20.0 - 1.0°C. The fish were maintained on a diet of shrimp
flakes and commercial tropical fish food.
Freshly preserved fish were allowed to set for several
days before measurements and counts were taken. This was
done to allow completion of preservation, as these fish
would be grouped with aged museum specimens. Setting also
affected erosion of the mucous layer covering the scales.
This layer seriously hinders the counting of scales.
Four measurements were recorded (to the nearest 0.1 mm)
for each fish. These were: standard body length, predor-
sal length, eye diameter, and body depth immediately poste
rior to the operculum. A binocular, widefield scope was
used as an aid in taking all measurements. Counts were
made of six meristic characters for each fish. These in
cluded numbers of pectoral rays, dorsal rays, anal rays,
principal caudal rays, vertical bars, and lateral scales
(from the first scale in contact with the operculum to the
last large scale in the region of the hypural plate).
Scales were counted on both sides and averaged if there was
a difference. Any mean value ending in 0.5 was raised to
the next whole number.
The scales in these fish are normally quite difficult
to count, and a technique was devised which greatly simpli
fied this problem. After all other measurements and counts
5
were taken, the fishes were placed in close proximity (7-10
cm) to an incandescent bulb and allowed to dry slightly.
They were then placed in a solution of methylene blue in
distilled water (1:200) for a period of approximately three
minutes. They were again dried for three to five minutes
under the lamp. With the aid of a dissecting scope the
scales could then be easily and accurately counted. Upon
return to the formalin the fish gradually lost their blue
color and were in no way harmed. The ray counts generally
proceeded without difficulty, but on occasion drying or
backlighting was necessary.
The fish were also sexed at the time of measurement.
This is a relatively simple procedure. The males have much
bolder barring than do the females (Fig. 2). The male has
a rounded anal fin while in the female it is angular. The
female also has a low sheath around the anterior portion
of the anal fin. Another sexual difference, previously un
recorded, is a black spot located above the pectoral fin
just posterior to the operculum. This spot is consistently
present in the males and absent in the females.
When possible, thirty animals, including fifteen males
and fifteen females, were analyzed from each locality. A
total of thirteen localities afforded this number of animals.
Where only a lesser number could be obtained, the animals
were measured and counts taken in the same manner but the
6
sample was not included in the analyses of variance or re
gression analyses as unequal sample size greatly burdened
the analysis. All samples were analyzed in terms of
descriptive statistics.
Each character was first analyzed for the presence of
sexual dimorphism. This was accomplished by single class
ification, analysis of variance. If sex influenced the
phenotypic expression of a character the males and females
were compared separately; if sex did not create a bimodal
distribution they were combined for study.
Data for certain characters suggested clinal variation.
To evaluate a possible clinal change in phenotypic expres
sion the various mean values for each character were re
gressed against locality on a south-north axis, the
southernmost locality being assigned a value of zero. All
other values were expressed in miles from this locality.
The locality was considered the independent variable and the
character, the dependent variable.
Twenty animals, five from each of four localities, were
examined for possible correlation between vertebral number
and lateral scale number. The scale counts were made as
previously described except that the scales were not stained,
The vertebral counts were made after clearing and staining
the fish in a modified method of Taylor (1967) as described
by Mitchell (1971). Vertebral counts were taken from the
7
first unfused neural spine to the last neural spine on the
hypural plate.
Logrithms were utilized where ratios were involved in
the evaluation of a character. Instead of dividing one
character by another, the log of the smaller value was sub
tracted from the log of the larger. This technique mini
mizes problems of normality often associated with ratios.
This procedure was used in evaluating eye diameter (log
standard length - log eye diameter) and predorsal length
(log standard length - log predorsal length).
Attempts were made to analyze four protein systems,
these systems being, hemoglobins, aromatic esterases, gen
eral proteins, and lactic dehydrogenase. Horizontal starch
gel electrophoresis was the method applied in studying these
systems. Animals for electrophoretic study were collected
from ten different localities, ranging from the Smokie Hill
River in west-central Kansas to the Pecos River in south
western Texas (Fig. 1; sites listed alphabetically). They
were maintained in the laboratory as previously described.
At least five fish from each locality were analyzed for each
system.
Each animal was prepared for study in the following
manner. The fish was held in one hand, and with a pair of
sissors in the other, the body was transversely cut into two
pieces, the cut being made just posterior to the anal
8
opening. The anterior portion of the fish was immediately
dropped into a graduated centrifuge tube (15 ml) containing
two drops of Sigma 14-5 anti-coagulant solution and six ml
amphibian Ringer's solution. The tube was gently shaken as
the fish was bled to prevent clotting of the blood. The
fish was removed after bleeding had stopped and the tube
was placed in ice. The liver of the fish was then removed
and placed in a centrifuge tube surrounded by ice.
The tube containing the blood was then centrifuged for
five minutes at 300 rpms, the supernate removed, six ml
Ringer's added, the red blood cells suspended by shaking
and again centrifuged. This procedure was repeated again
and the supernate discarded. Three drops of distilled water
were added to the "RBCs" as a hemolyzing agent. The cells
were further hemolyzed by freezing and thawing. Again the
tube was centrifuged to free the hemoglobin of cellular
debris. The hemoglobin was then placed in a freezer for
subsequent study.
Three drops of distilled water were added to the tube
containing the liver. It then was reduced to a homogenate
with a glass rod. The homogenate was centrifuged and frozen
for later use.
Separation of blood hemoglobins was accomplished by
utilizing the pH 8.6 buffer of Smithies (1959). The gels
were formed in a 12 x 20 x 0.8 cm mold using 12%
9
Electrostarch and stock buffer diluted one volume buffer to
four volumes de-ionized, distilled water; the electrode
buffer was not diluted. Electrophoresis was accomplished
using both the "comb plate" method and the paper tab method.
Both proved similarly successful. DC voltage was supplied
by a GELMAN Model # 38201 power supply. The gels were run
under refrigerated conditions for five hours at 200V. Stain
ing was effected with Amido-schwartz lOB (0.2 gm in 250 ml
methanol); acetic acid: distilled water (10:2:10). De-
staining and hardening of the gel was carried out in the
just mentioned solution minus the Amido-schwartz black.
The methods applied in the esterase study were essen
tially the same as that previously described, the exception
being that liver homogenate was used rather than blood and
a different staining technique was utilized. The reagent
for esterase staining contained one ml alpha-napthyl acetate
(1 gm/100 ml acetone), 20 mg Fast Blue RR and 50 ml Tris-
malate buffer at a pH of 7.0. The sliced gel was placed in
this solution for a period of five to thirty minutes.
The buffer systems used in the analysis of LDH were
the same as previously described. Staining was accomplished
by the tetrazolium method (Fine and Costella, 1963).
The fourth system, general proteins, was run with the
same technique as described for hemoglobins except that
liver homogenate was used in the slots.
CHAPTER III
RESULTS
Morphological Analysis
Thirteen of the 20 localities provided a sample of 15
males and 15 females. Studies of sexual dimorphism and
clinal variation were made on these samples.
Of the seven characters analyzed for sexual dimorphism
only one revealed sexual variation. The position of ante
rior insertion of the dorsal fin is located more posteriorly
in females than in males. For the samples studied, the dif
ference was found to be highly significant (0.001 level).
No other characters, other than those mentioned in the
previous section, showed any evidence of sexual dimorphism
(Table 1, A-G). Although no statistical testing was con
ducted on the smaller samples with regard to sex it was
assumed that these samples do not differ markedly from the
larger samples in this respect. For this reason the males
and females were combined for analysis of the descriptive
statistics for all characters except predorsal length and
barring (limited to males). This was done in order to
provide a larger sample size.
The regression of scale number upon location on a north-
south axis proved to be statistically highly significant
(0.001 level). In other words, as distance from the
10
11
southernmost locality increased, there was a corresponding
increase in scale number (Fig. 3). As may be seen, the
correlation is not perfect but a definite trend is indi
cated. The several noticeable reversals in scale number
seem to be random in nature as the variation in one partic
ular stream is in some cases more pronounced than that
observed in adjacent drainages.
As eye diameter rather than preorbital width appears
to vary geographically, eye diameter was analyzed in terms
of standard body length, the margin of error being less
critical. As mentioned previously, log values were used to
alleviate problems of normality. The resultant log value
was regressed on locality and again the results proved to
be highly significant (0.001 level). Some component of
location affects eye diameter in a statistically significant
manner. The results of this regression is given in Table 2F.
As log values were used in analyzing eye diameter, confi
dence interval and standard deviation are not presented.
The difference in terms of log values for each locality is
graphed in Figure 4 so that some concept of the geographic
variation in eye diameter may be observed. In this case
the larger logrithmic values denote a smaller comparative
eye diameter.
The characters, pectoral fin ray number, dorsal fin ray
number, anal fin ray number, and principal caudal ray number
12
were evaluated in the manner described for the previous two
characters. Tables 3 and 4 give the mean values, one stan
dard deviation and 95% confidence intervals for each local
ity. These data are not presented graphically as there are
no consistent geographic trends. Significant variation is
observed in comparing certain localities but this variation
does not appear to be correlated with north-south locus or
drainage system.
Body depth was recorded for each fish but it was later
decided to disregard this character. The body design of
the fish is such that nutritional state and stomach contents
affect body depth.
Vertical bar number was recorded for all animals but
only analyzed in the males, as barring in the females was
sometimes faint or absent. Here too, minor variation of
number could not be attributed to either stream system or
north-south location (Table 3C).
Both methods, pooled and unpooled, of correlating ver
tebral number and scale number (Table 5, A-B) gave the same
results. Scale number is significantly correlated with
number of vertebrae (0.05 level).
Electrophoretic Analysis
Of the four systems studied, only two, the hemoglobins
and esterases, gave results adequate for critical analysis.
Neither system revealed any differences among localities
13
and there was no indication of isozyme polymorphism at any
locality. The two systems are shown in Figure 2. To facil
itate presentation of the different electrophoretic patterns
the typical complete banding is drawn for each system.
This method of presentation is used for two reasons: one,
no difference was observed among the various localities
studied, and two, no single gel was representative of all
localities. One or two locations always seemed to run
"lopsided" or streaked. Each system was run repeatedly, so
in the case where a sample ran poorly on one gel it could
be checked for consistency on another gel.
The most highly resolved system proved to be the hemo
globins. Four anodal and four cathodal bands were expressed
(Fig. 5). The leading anodal band appeared wide but clearly
and consistently defined. The two intermediate bands were
separated only slightly with the faster being the better
defined band. The slowest of the four was well defined but
showed little movement. The cathodal bands appeared as two
distinct pairs, one slow, the other intermediate in speed.
Another member of the family Cyprinodontidae (Cyprinodon
rubrofluviatilis) was run with the Fundulus for comparison.
This fish is commonly found in much the same habitat as the
plains killifish. While no differences were evident among
the killifish the pupfish was obviously different. Its pat
tern is shown in Figure 5B. It separated into three anodal
14
bands, the lead band migrating only as far as that of the
second Fundulus band. There were five distinct cathodal
bands for Cyprinodon as opposed to four in Fundulus.
The study of aromatic esterases in Fundulus gave the
same results as did the hemoglobins: no variation was
noted. A wide leading anodal band (Fig. 5C) followed by a
weakly defined, narrow band was observed for Fundulus, while
Cyprinodon expressed a weak leading band and a narrow, well
defined second band. No cathodal bands were observed for
either of the two fish.
15
16
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29
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30
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H C N o o ^ i n v o r - o o c T i O H O M o o rj" in ijD r^ 00 cTi o rH rH H H rH rH CM
31
TABLE 5
DEGREE OF CORRELATION BETWEEN SCALE NUMBER AND VERTEBRAL NUMBER
Locality Correlation
Little Silver Creek, Tex. Method One—Pooled values for scale # vertebrae # each locality-equal weight
n=4 d.f.=2
r^2 = 0.959*
^.05 (2)= 0.950
LS 1 LS 2 LS 3 LS 4 LS 5 Y
42 45 46 46 48 45.4
28 30 29 30 30 29
t.01(2)= °-950
Dbl. Mtn. Fork, Brazos, Post, Tex. scale # vertebrae #
p 1 P 2 P 3 P 4 P 5 Y
45 46 50 41 43 45. 0
29 28 29 29 28. 75
Method
n=18
^12
Two--Pooled localities
d.f.=16
= 0.611**
'^.05(16)= 0.468
.01(16)= 0-590
Pease Riv., Roaring Sp., Tex. scale # vertebrae #
RS 1 RS 2 RS 3 RS 4 RS 5 Y
46 47 51 50 49 48.6
30 29 30
29 29.5
Smokie Hill River, Kansas scale # vertebrae #
SH 1 57 30 SH 2 58 30 SH 3 57 30 SH 4 58 32 SH 5 54 32 Y 56.8 30.8
CHAPTER IV
DISCUSSION
Most of the characters analyzed in this study exhibited
remarkably little geographic variation. Variation in pec
toral ray number, dorsal ray number, anal ray number, prin
cipal caudal ray number, and vertical bar number (males)
appeared to be for the most part of a random nature. For
each character there are localities with mean values that
appear to be significantly different from those of certain
other localities, but no consistent geographic pattern is
indicated by these differences. The localities showing the
greatest divergence for one character may exhibit almost no
difference for another.
The two characters, eye diameter and lateral scale num
ber, exhibit geographic variation in terms of a north-south
cline. Eye diameter decreases with increasing north lati
tude (Fig. 5) while scale number increases with increasing
north latitude (Fig. 3). The expression of these characters
is related to their location at a statistically, highly
significant level.
While the cause of these clines may well be of a ge
netic origin there is persuasive evidence that one or both
characters may be under environmental influence. Salinity
and water temperature, as well as other environmental
32
33
factors, can modify morphological appearance in some ecto-
thermal vertebrates and invertebrates. Previous workers
have found that temperature in particular can affect pheno
typic expression in fishes. One of the earliest workers to
discuss the effects of temperature was Garman (1895). In
the very paper that he decrees F. kansae a species distinct
from F. zebrinus he implies that the characters that dis
tinguish them may not be valid. The following paragraph is
a direct quote from his paper:
By recent discussion attention has been directed to a decrease in the number of vertebrae, of fish in general, in and toward the torrid zone, and several theories have been propounded to account for the phenomenon. The species of this family (Cyprinodontidae) and others have been somewhat carefully studied,-first to determine the facts, and second, to test the theories . . . It is true a decrease obtains (vertebral number), with few exceptions, in the direction of warmer waters, but warmth of water is attended by both increase in the amount of food and decrease in the need of it, thus lessening the comparative activity of the species. Some would ascribe the differences directly to natural selection. This hypothesis of course cannot be proved; it begs the entire question. It is also found that with the decrease in number of vertebrae, there is in some cases a decrease in the number of fin rays and scales.
A considerable amount of experimental work has been
done by various workers which tend to support and explain
some of the basic ideas of Garman. Gabriel (1944) found
that in F. heteroclitus vertebral number was higher in fish
hatched at lower temperatures and, conversely, was lower at
higher temperatures. Svardson (1952) in working with the
34
coregonids found that by transplanting these fish he was
able to demonstrate the environmental plasticity of certain
characters. He indicated that scale number could be af
fected by temperature and nutritional state of the female
parent. Taning (1952) delved deeper into the problem and
was able to relate the effect of temperature on the pheno
typic expression of a certain character to a particular
time frame in the embryological life of the fish.
Salinity may also have an effect upon expression of
scale number. While Taning found that vertebral number is
set before the vitelline membrane becomes permeable to salts
Motley (19 34) , in working with Salmo kamloops, found that
scale number was set later in ontogeny. The vitelline mem
brane, may at this time, be permeable to various ions.
It is apparent that environmental factors may affect
the development of certain morphological characters in
fishes, although these factors may not have the same effect
in all species. Only future work will provide the exact
cause of clinal variation in lateral scale number and eye
diameter in Fundulus. For the present it can only be said
that although genetic differences may be involved, there is
reason to suspect that the variation is the result of the
direct effect of some component of the environment.
Only two of the electrophoretic systems studied gave
sufficient resolution to be considered reliable. These' two
35
systems, hemoglobins and esterases, were run repeatedly and
all results were the same--no difference could be observed
at the molecular level. In comparing the electrophoretic
bands with another member of the same family, Cyprinodon
rubrofluviatilis, obvious differences were noted.
On the basis of the evidence of this study, there seems
no justification for maintaining any taxonomic distinction
between the two fish. They quite obviously do not merit
separation at the specific level and there does not appear
to be sufficient justification for separation at the sub-
specific level. Lateral scale number and eye diameter are
the only characters studied which show appreciable varia
tion and this is of a clinal nature. This geographic varia
tion could be an expression of environmentally influenced
phenotypic plasticity rather than an expression of genetic
differences. Various workers, with other fish, have shown
that scale number can be influenced by various components
of the environment. Though the effects of various environ
mental components upon eye diameter have not been investi
gated it may well be that the same forces are operating in
this case.
In accepting the fact that the two fish are conspecific
the problem of what they should properly be called then
arises. After a thorough review of the literature it was
concluded that Fundulus zebrinus Jordan and Gilbert stands
36
as the first available name for the fish in question. The
following sijmmary of the literature is offered in support
of that conclusion. It also provides a taxonomic history
of the fish.
Fundulus kansae=zebrinus v;as first recorded by Dr.
C. M. Girard (1859). The Fish were collected by a Lieuten
ant J. C. Ives, the locality being listed as "between Fort
Defiance and Fort Union, New Mexico." Girard proposed the
taxon, Hydrargyra zebra, "in allusion to the numerous lat
eral bars." The generic allocation, however was incorrect.
Giinther (1866) assigned the name, Fundulus zebra, to the
fish and gave its distribution as the "upper affluents of
the Rio Grande del Norte." Jordan and Gilbert (1882) again
listed the fish of Girard, calling it F_. zebra. In the same
publication, however, F. zebra was also listed as a synonym
of F. adinia. In the addendum to their work of 1882 (p.
891), Jordan and Gilbert noted that Fundulus zebra was pre
occupied in the genus and proposed the replacement name,
Fundulus zebrinus. Gilbert (1884) gave a full description
of F. zebrinus based on three specimens from Ellis, Kansas.
He stated that they were the first specimens seen since the
original discovery of the species in 1859. The name,
Fundulus kansae, was proposed in 1895 by Garman who placed
it in a separate subgenus (Plancterus). He indicated that
this fish was not the one to which F. zebrinus was first
37
applied. The type locality was given as Kansas. Jordan
and Evermann (1896), however, stated that:
. . . There is no doubt that the original F zebra is the species called zebrinus by us and ka^nsae by Garman. It came from some point between 'Fort Union and Fort Defiance.' In other words, it came from the headwaters of the Canadian River or the Rio Grande. No species of this type has been recorded from the upper Rio Grande, but the species called zebrinus and kansae is in all the upper waters of the Arkansas basin, to which the Canadian River belongs, and doubtless in the streams above Fort Union.
In the same paper Jordan and Evermann suggestec3 that
the subgenus (Plancterus), possibly merited generic status.
Carl Hubbs (1926) did elevate Plancterus to generic rank and
included two species, P. zebra and P_. kansae, the former with
41 to 49 scale rows, a more robust body and larger eyes--the
latter with 52 to 64 scale rows. The name, Plancterus, was
subsequently used by Koster (1948) in a description of the
spawning activities of the killifish. In Knapp's work of
1953, however, the generic epithet, Fundulus, was used. He
listed F. zebrinus with a distribution that included the
Rio Grande and tributaries from Brownsville to New Mexico,
and F. kansae with a distribution that included the upper
Arkansas River basin and upper parts of the Red, Colorado,
and Brazos Rivers. Miller (1955) reviewed the genus,
Fundulus, and denounced Hubbs' recognition of Plancterus.
He gave the distribution of F. zebrinus as the upper por
tions of the Colorado, Brazos, and Pecos River drainage,
38
and that of F. kansae as from South Dakota to Texas (Red
River) and New Mexico (Arkansas River). Subsequent authors
have followed Miller.
It seems clear that the name Fundulus zebrinus, pro
posed by Jordan and Gilbert in 1882 as a replacement name
for the Fundulus (Hydrargyra) zebra of Girard, is the
earliest available name, predating the name, Fundulus kansae,
by some thirteen years. The name of the Plains killifish,
therefore, should be Fundulus zebrinus Jordan and Gilbert.
CHAPTER V
SUMMARY
According to the current literature, there are two
species of the genus Fundulus in the saline alkaline waters
of the Central Plains region of the United States. These
fish are F. zebrinus and F. kansae. These forms have been
distinguished on the basis of lateral scale number and eye
diameter. Recently, several authors have suggested the
possibility of conspecificity between the two fish.
An analysis was made of variation in a number of char
acters in order to determine the systematic status of the
two forms. Emphasis was placed on morphological analysis.
Ten characters were analyzed, either singly, or in combina
tion if size was a factor (i.e., eye diameter v.s. standard
body length). Only two characters yielded variation of in
terest. Both lateral scale number and eye diameter vary in
a clinal manner. Relative eye diameter decreases in a north
ward direction on a north-south axis while scale number in
creases in the same direction. This variation seems to be
in no way associated with the various drainage systems or
with the presumed distributional limits between the two
fishes. Direct environmental effects rather than genetic
differences may be the cause of this variation.
Electrophoretic analysis of two protein systems, hemo
globins and esterases, failed to reveal any differences in
39
40
the fish. There was no indication of molecular variation
among the various localities studied, nor was there evidence
of isozyme polymorphism at any particular locality. It was
concluded that there is no evidence to support separation of
£. kansae and F. zebrinus as distinct species.
A review of the taxonomic literature indicates that the
name Fundulus zebrinus Jordan and Gilbert should be applied
to the populations formerly included in F. zebrinus and F.
kansae.
LITERATURE CITED
Blair, W. F., A. P. Blair, P. Brodkorb, F. R. Cagle, and G. A. Moore. 1968. Vertebrates of the United States. McGraw-Hill Book Company, New York, 616 pp.
Eddy, Samuel. 196 9. How to know the fresh water fishes. Wm. C. Brown Company Publishers, Dubuque, Iowa, 286 pp.
Fine, I. H., and L. A. Costello. 1963. The use of starch electrophoresis in dehydrogenase studies. In Colowick, S. P., and N. O. Kaplan (eds.), Methods in enzymology, Vol. 6, Academic Pre»s, New York.
Gabriel, M. L. 1944. Factors effecting the number and form of vertebrae in Fundulus heteroclitus. J. Exp. Zool., 95:105-147.
Garman, Samuel. 189 5. The Cyprinodonts. Mem. Mus. Comp. Zool., Harvard Coll., 19:1-179.
Gilbert, C. H. 1884. Notes on the fishes of Kansas. Bull. Washburn Lab. Nat. Hist., 1:15.
Girard, Charles M. 1859. Ichthyological notices. Proc. Acad. Nat. Sci. Phil., pp. 60-61.
Giinther, A. 1866. Catalog of the fishes in the British Museum, Vol. 6, 8 8 pp.
Hubbs, Carl L. 1926. Studies of the fishes of the Order Cyprinodontes. VI. Material for a revision of the American genera and species. Misc. Publ. Mus. Zool. Univ. Mich., 16:1-86.
Jordan, D. S., and B. W. Evermann. 1896. The fishes of North and Middle America. Bull. U.S. Nat. Mus., 47, 4. vols., 3,313 pp., 392 pis.
Jordan, D. S., and C. H. Gilbert. 1882. Synopsis of the fishes of North America. Bull. U.S. Nat. Mus., 16, 8 vols., 1,074 pp.
Knapp, F. T. 1953. Fishes found in the fresh watery of Texas. Ragland Studio and Litho Printing Company, Brunswick, Georgia, 166 pp.
Koster, W. J. 1948. Notes on the spawning activities and the young stages of Plancterus kansae (Garman). Copeia, 1948(1) :25-33.
41
42
1957. Guide to the fishes of New Mexico. Univ. New Mexico Press, Albuquerque, New Mexico, 116 pp.
Metcalf, A. L. 1966. Fishes of the Kansas River system in relation to zoogeography of the Great Plains. Mus. Nat. Hist., Univ. Kans. Publ., 17 (3) : 23-189.
Miller, Rcpbert R. 1955. An annotated list of the American Cyprinodontid fishes of the genus Fundulus, with the description of Fundulus persimilis from Yucatan. Occ. Papers Mus. Zool., Univ. Mich., 568:1-25.
Mitchell, R. W., and R. E. Smith. 1971. Some aspects of the osteology and evolution of the neotenic spring and cave salamanders (Eurycea, Plethodontidae) of central Texas. Tex. J. Sci., 23:343-362.
Mottley, C. McC. 1934. The effect of temperature during development on the number of scales in Kamloops trout, Salmo kamloops Jordan. Contr. Canad. Biol., 8:254-263.
Pflieger, William L. 1971. A distributional study of Missouri fishes. Mus. Nat. Hist., Univ. Kans. Publ., 20 (3) :225-570.
Smithes, O. 1959. Zone-electrophoresis in starch gels and its application to studies of serum proteins. Advan. Protein Chem., 14:65.
Svardson, G. 1952. The coregonid problem. IV. The significance of scales and gill rakers. Inst. Freshwater Research, Drottningholm, No. 33:204-232.
Tuning, A. Vedel. 1952. Experimental study of meristic characters in fishes. Biol. Rev., 27:169-193.
Taylor, W. R. 196 7. An enzyme method of clearing and staining small vertebrates. Proc. U.S. Nat. Mus., 132(3596):1-17.
