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Life History Patterns of Gambusia marshi (Poeciliidae) from Cuatro Cinegas, Mexico Author(s): Gary K. Meffe Source: Copeia, Vol. 1985, No. 4 (Dec. 10, 1985), pp. 898-905Published by: American Society of Ichthyologists and Herpetologists (ASIH)Stable URL: http://www.jstor.org/stable/1445239Accessed: 01-10-2015 15:50 UTC

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COPEIA, 1985, NO. 4 COPEIA, 1985, NO. 4

SELANDER, R. K., AND T. S. WHITTAM. 1983. Protein polymorphism and the genetic structure of populations, p. 89-144. In: Evolution of genes and pro- teins. M. Nei and R. K. Koehn (eds.). Sinauer Assoc. Inc., Sunderland, Massachusetts.

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SELANDER, R. K., AND T. S. WHITTAM. 1983. Protein polymorphism and the genetic structure of populations, p. 89-144. In: Evolution of genes and pro- teins. M. Nei and R. K. Koehn (eds.). Sinauer Assoc. Inc., Sunderland, Massachusetts.

SHAKLEE,J. B., AND C. S. TAMARU. 1981. Biochem- ical and morphological evolution of Hawaiian bone- fishes (Albula). Syst. Zool. 30:125-146.

SOKAL, R. R., AND F.J. ROHLF. 1969. Biometry. Free- man and Co., San Francisco, Calif.

TODD, T. N., G. R. SMITH AND L. E. CABLE. 1981. Environmental and genetic contributions to morphological differentiation in ciscoes (Coregoninae) of the Great Lakes. Can. J. Fish. Aquat. Sci. 38:59- 67.

UTTER, F. M. 1981. Biological criteria for definition of species and distinct intraspecific populations of anadromous salmonids under the U.S. Endangered Species Act of 1973. Can. J. Fish. Aquat. Sci. 38: 1626-1635.

VAN VALEN, L. 1978. The statistics of variation. Evol. Theory 4:33-43.

VRIJENHOEK, R. C., AND S. LERMAN. 1982. Hetero- zygosity and developmental stability under sexual and asexual breeding systems. Evolution 36:768- 776.

WAINWRIGHT, T. 1982. Milkfish fry seasonality on Tarawa, Kiribati, its relationship to fry seasons elsewhere, and to a sea surface temperature (SST). Aquaculture 26:265-271.

WAKE, D. B. 1981. The application of allozyme evidence to problems in the study of morphology, p. 257-270. In: Evolution today; Proc. 2nd Int. Congr. Syst. Evol. Biol. G. G. E. Scudder and J. L. Reveal (eds.). Carnegie Mellon University, Pittsburgh, Pennsylvania.

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NORTHWEST AND ALASKA FISHERIES CENTER, NATIONAL MARINE FISHERIES SERVICE, NA- TIONAL OCEANIC AND ATMOSPHERIC ADMI- NISTRATION, 2725 MONTLAKE BOULEVARD EAST, SEATTLE, WASHINGTON 98112. Ac-

cepted 26 Feb. 1985.

WAINWRIGHT, T. 1982. Milkfish fry seasonality on Tarawa, Kiribati, its relationship to fry seasons elsewhere, and to a sea surface temperature (SST). Aquaculture 26:265-271.

WAKE, D. B. 1981. The application of allozyme evidence to problems in the study of morphology, p. 257-270. In: Evolution today; Proc. 2nd Int. Congr. Syst. Evol. Biol. G. G. E. Scudder and J. L. Reveal (eds.). Carnegie Mellon University, Pittsburgh, Pennsylvania.

WINANS, G. A. 1980. Geographic variation in the milkfish Chanos chanos. I. Biochemical evidence. Evolution 34:558-574.

WRIGHT, S. 1978. Evolution and the Genetics of Pop- ulations. Vol. 4. Variability Within and Among Nat- ural Populations. University of Chicago Press, Chi- cago, Illinois.

NORTHWEST AND ALASKA FISHERIES CENTER, NATIONAL MARINE FISHERIES SERVICE, NA- TIONAL OCEANIC AND ATMOSPHERIC ADMI- NISTRATION, 2725 MONTLAKE BOULEVARD EAST, SEATTLE, WASHINGTON 98112. Ac-

cepted 26 Feb. 1985.

Copeia, 1985(4), pp. 898-905

Life History Patterns of Gambusia marshi (Poeciliidae) from Cuatro Cienegas, Mexico

GARY K. MEFFE

The life history and ecology of Gambusia marshi, a poeciliid fish endemic to the Cuatro Cienegas basin and Rio Salado drainage of Coahuila, Mexico, is virtually unknown. Fishes collected in different seasons from natural lakes, rivers and an artificial canal were analyzed for reproductive patterns, food choice and parasitism. G. marshi reproduced seasonally, with fecundity increasing as a function of female size. Reproduction is not strongly habitat dependent, although reduced reproductive activity was noted in the canal. Superfetation was infre- quent. Major food items of G. marshi were detritus and insects, with other invertebrates, plant material and juvenile fish also represented. Somatic condition was little affected by habitat or season and most individuals were robust. Parasites included two nematodes, a trematode and an acanthocephalan. G. marshi is a habitat and food generalist, which perhaps accounts for its local abundance and success within its limited range.

Copeia, 1985(4), pp. 898-905

Life History Patterns of Gambusia marshi (Poeciliidae) from Cuatro Cienegas, Mexico

GARY K. MEFFE

The life history and ecology of Gambusia marshi, a poeciliid fish endemic to the Cuatro Cienegas basin and Rio Salado drainage of Coahuila, Mexico, is virtually unknown. Fishes collected in different seasons from natural lakes, rivers and an artificial canal were analyzed for reproductive patterns, food choice and parasitism. G. marshi reproduced seasonally, with fecundity increasing as a function of female size. Reproduction is not strongly habitat dependent, although reduced reproductive activity was noted in the canal. Superfetation was infre- quent. Major food items of G. marshi were detritus and insects, with other invertebrates, plant material and juvenile fish also represented. Somatic condition was little affected by habitat or season and most individuals were robust. Parasites included two nematodes, a trematode and an acanthocephalan. G. marshi is a habitat and food generalist, which perhaps accounts for its local abundance and success within its limited range.

THE Cuatro Cienegas region, an intermon- tane basin west of Monclova, Coahuila,

Mexico, is well known for its high degree of biological endemism (Taylor and Minckley, 1966; Marsh, 1984). Aquatic endemics include species of crustaceans, molluscs, fishes and tur-

THE Cuatro Cienegas region, an intermon- tane basin west of Monclova, Coahuila,

Mexico, is well known for its high degree of biological endemism (Taylor and Minckley, 1966; Marsh, 1984). Aquatic endemics include species of crustaceans, molluscs, fishes and tur-

tles (Minckley, 1969). Despite intense interest in this biota, particularly in the fishes (reviewed by Minckley, 1984), few comprehensive studies have been conducted on basic ecology and life histories of its component species. With grow- ing awareness of the scientific value of this area,

tles (Minckley, 1969). Despite intense interest in this biota, particularly in the fishes (reviewed by Minckley, 1984), few comprehensive studies have been conducted on basic ecology and life histories of its component species. With grow- ing awareness of the scientific value of this area,

? 1985 by the American Society of Ichthyologists and Herpetologists ? 1985 by the American Society of Ichthyologists and Herpetologists

898 898


MEFFE-GAMBUSIA MARSHI LIFE HISTORY

potentials for human-induced changes and re- sultant conservation concerns (Contreras-Bald- eras, 1984), it is appropriate to assemble life history information regarding Cuatro Cienegas fishes.

Gambusia marshi Minckley and Craddock (Poeciliidae) is native to the Cuatro Cienegas basin and the Rio Salado drainage of Coahuila. Occurring in two color morphs, a light, spotted phase and a striped, melanistic phase (Minckley, 1962), it is ". .. perhaps the most abundant fish in the Cuatro Cienegas basin ..." (Minckley, 1969). Despite its abundance and general rep- resentation in collections, little has been published on G. marshi since its description more than 20 years ago (Minckley, 1962). Included are reports on laboratory hybridization with G. affinis (Minckley, 1964), laboratory study of mate choice by males (Arnold, 1966), a discussion of distribution and occurrence within the Cuatro Cienegas basin (Minckley, 1969, 1984), chro- mosome morphology (Campos and Hubbs, 1971) and details of male and female genital morphologies (Peden, 1972a, b).

I investigated reproductive parameters, food utilization and parasite occurrence in spotted phase G. marshi over four seasons from three major habitats of Cuatro Cienegas: shallow lakes (lagunas), rivers and an artificial canal. Seasonal and spatial (habitat) variation in life history of G. marshi was thus obtained for a gross analysis of its ecology.

MATERIALS AND METHODS

Specimens used.--All analyses were conducted on preserved specimens housed in the Arizona State University (ASU) Museum, collected by various personnel from 1964-1970, but mostly 1964-1965. Because collections were not made specifically for comprehensive life history studies, I selected habitats best represented and for which the largest number of specimens was available. Consequently, two habitat categories included collections from several different localities, while the seasonal analysis included collections from several years. Seasonal designa- tions are: winter = Dec.-Jan.; spring = April; summer = June; autumn = Aug.-Sept.

The following collections were utilized (listed are localities as in Minckley [1969], ASU museum number and collection date): Lagunas- San Pablo Laguna, 625, 24 Jan. 1964; Laguna Grande, 1746, 15 Apr. 1965; Ferrinios Laguna, 955, 9June 1964; Laguna Grande, 5967, 2 Sept.

1970. Rivers-Rio Salado, 2852, 21 Dec. 1966; 1725, 13 April 1965; Puente Colorado, 967, 10

June 1964; 5989,4 Sept. 1970. Canals-La An- gostura, 620, 23Jan. 1964; 1731, 13 April 1965; 934, 7 June 1964; 2260, 13 Aug. 1965.

Length-frequency analysis.-All specimens from each collection were sexed and placed in 1 mm (standard length, SL) size categories. One to three mature females were randomly selected from each category for further analysis, so that a total of 20-30 females representing the size range of maturity were selected (three small collections allowed analysis of only 18, 18 and 11 individuals). These fish were used in all subsequent procedures. Most collections were made by 3.2 mm mesh seines, but some were by 6.3 mm mesh and mesh sizes may have influenced size distributions in collections.

Reproductive and somatic analysis. -Females were measured to the nearest 0.1 mm SL with a dial caliper. Ovaries were removed and contents counted under a dissecting microscope (7x). Eggs and embryos were placed into one of six categories, primarily for detection of superfetation: 1) immature ova-ova in the process of yolking, but sub-mature in size; 2) mature ova/ fertilized egg-full-sized ova, unfertilized or re- cently fertilized; 3) primitive streak-primitive streak present, but eyes not yet distinguishable; 4) early eyed-eyes present, but not full sized; little dorsal pigmentation; 5) middle eyed-eyes full sized; moderate to extensive dorsal pigmentation; and 6) late eyed-little yolk re- maining; near parturition.

Categories 2-6 were summed to obtain total number of eggs and embryos carried, or "total reproduction" (TR). Category 1 was considered preparatory to actual reproduction since it included immature members. Subsequent to counting, ovaries and their contents were placed into individual tared aluminum pans, dried to constant weight at 85-90 C for 24-28 hr and weighed to the nearest 0.1 mg on a Mettler analytical balance. The remainder of the fish, minus the digestive tract (below), was similarly treated and weighed. I thus obtained reproductive and somatic dry weights (RDW and SDW), respectively. Since all fish were preserved in 10% formalin and stored in 35% iso- propanol, potential effects of preservation on length or weight should be equivalent among groups.

A somatic condition factor was calculated for

899


COPEIA, 1985, NO. 4

WINTER

50- 40- Y=1.147X - 26.6 : Y=1.24X -25.0

r=8 896 - r= 923

20- 8

10- i *

, 'Ih V 1 I I I I 1 I

50- 40 Y .031X- .34

- r =.086 N.S. 30- 20-

10-

'tIT T, r, I . . .I

50-

40-

CANA L 30- 20-

10-

20 24 28 32 36 40 44

Y=1,66X -38.2 r =930

I 1I I I I I I

SUMMER

Y =.045X2- 2.22X + 27.5 r = .917

,I , t ; I I

Y =.476X - 9.8 r = .698

I I I I

AUTUMN

Y =1.18X - 24.3 r = .837

Y =.240X - 5.3 r=.653

,~ , , I . I.

Y =.653X - 11.3 Y= .073X2 - 3.93X 56.3 Y .140X-3.6 r=.875 r=.862 r =.460

20 24 28 32 36 40'44 20 '2428'32'36 '4'4 44 2 24 28 32 36 40 44 STANDARD LENGTH (mm)

Fig. 1. Regressions of total reproduction on standard length for Gambusia marshi by habitat and season. The winter laguna regression included only reproductively active fish. The spring laguna regression does not include the extreme value at 41 mm SL, considered an outlier. A regression was not conducted for the winter canal sample, since all observations were zero and thus collinear. N.S. indicates statistically non-significant product-moment correlation coefficients; the remainder are significant at P < .05 or better. Small arrows indicate two identical observations.

each fish as SCF = (SDW/SL) x 100 and reproductive effort was calculated as RE = (RDW/ SDW + RDW) x 100, or the percentage of total weight invested in reproduction. The relationship between dependent variables TR, SCF, or RE and the independent variable SL was investigated using a regression analysis program (BMDP5R, Dixon et al., 1981) on the ASU IBM system. A linear model was used as a descriptor of the relationship between the dependent variable and SL. In four cases a second order poly- nomial was used instead since it improved the correlation coefficient by at least 10%. These models are included simply as aids in visualizing relationships between variables.

Food habits. -The entire length of the digestive tract was removed (above) and opened length- wise and contents were examined under a dissecting microscope (7-21x). Contents were broadly classified as detritus, invertebrates, vascular plant material, turbellarian flatworms (planarian-like), or fishes. Detritus consisted of a variety of organic and inorganic materials in- cluding mud and debris, but was frequently invested with diatoms and unicellular or filamen- tous algae, as revealed under higher power (40- 100 x). Invertebrates consisted primarily of insects, but also included spiders, ostracods and small unidentified crustaceans. Vascular plants included small seeds and broken stems. Food contents were quantified by visually estimating,

at 5% intervals, the percentage of gut filled by each category.

Parasites.-Gut and coelom parasites were collected as encountered. No systematic search was made for parasites.

RESULTS

Length-frequency analysis.-Male G. marshi generally matured between 18 and 20 mm SL, with the smallest mature male 17.6 mm and the largest in the 31 mm size class. Females matured at 20-22 mm and ranged upward to 47 mm SL. Fish from rivers were generally smaller than those from canals or lagunas, but no consistent seasonal size trends were noted.

Reproductive and somatic analyses.-Numbers of ova/embryos carried by G. marshi were posi- tively related to female size (Fig. 1). The smallest individual carrying an embryo was 22.0 mm SL, but fish typically began to yolk ova in the 20-22 mm range. Reproduction was strongly seasonal, with little activity in winter and autumn and peaks in spring and summer. An ex- ception was females from lagunas, which were reproductively active in all seasons although less so in autumn and winter (Fig. 1). All embryos in the winter (an.) laguna sample were in stage 2, indicating reproduction for that year was just commencing.

900

SPRI NC

u D

RIVERS a


WINTER

50-

40- Y -.698X + 47.5 r=-648 N.S

LAGUNAS 30- 20-

t0- ??

.

~ I I I I'

0 LI ..

'IVERS >

U C)

50- - Y=.128X-1.1

r= 117 N.S. 30-

20-

10-

f^T-.f t;- p , I I .

SPRING

Y =-.133X2+97X -147.1

r=.851

- I . I

Y=2.15X- 471 r .910

SUMMER AUTUMN

Y =.654X -13.5 . Y=.390X 4.1 r =.702 r=.353 N.S.

,l , , , . i . , 1 . *i 1 * . , * .

Y=.336X-.85 Y.618X-12.9 r =.324 N.S. r=.576

J ,

L 50-

40- Y -.014X +74 r. 239 N.S.

-ANAL 30-

20-

10-

20 24 28 32 36 40 44

Y -.147X2 9.2X-124.4 Y= 217X +5,9 r=.858 r .189 NS.

20 24 28 32 36 40 44 20 24 28 32 36 40 44 STANDARD LENGTH (mm)

Y=.336X-8.1 r= .419

20 24 28 32 36 40 44

Fig. 2. Regression of reproductive effort on standard length for Gambusia marshi by habitat and season. Protocol as in Fig. 1.

Superfetation, for purposes here, is defined as carrying ova/embryos in two or more non- consecutive stages of development. Consecutive stages (i.e., #2 and #3) were not considered in- stances of superfetation since they may repre- sent slow development by some embryos, or an error in classification by the observer. With this definition only 6 of 251 (2.4%) mature females superfetated; it was observed once in the canal (spring, stages 1 and 6), four times in lagunas (summer, stages 1, 2 and 6; autumn, stages 2 and 4, 2 and 5, and 1 and 5) and once in rivers (spring, stages 1, 2 and 6). Superfetation is thus rare in G. marshi.

Reproductive effort as a function of SL is plotted in Fig. 2. The relation between RE and

SL, although inconsistent, is usually positive. A low reproductive investment occurred in autumn and winter in all habitats except lagunas, where the reproductive season was extended. Generally low coefficients of determination (r2) indicate that SL is a poor predictor of RE, or conversely that RE is somewhat independent of length.

Somatic condition factor as a function of SL is plotted in Fig. 3. SCF's were consistent among seasons and habitats, indicating that somatic condition was little influenced by spatial or temporal change.

Food habits.--G. marshi is primarily a detriti- vore/insectivore (Fig. 4). The dominant item

WINTER

1.0-

8 Y=.022X-.41 r-,952

.6- LAGUNAS

-

.4- e 2

COPEIA, 1985, NO. 4

WINTER

LAGUNAS

70.0 47.3

RIVERS

17.8

CANAL I

61.8

[I EMPTY [ E FISH U

88.6

PLANTS FLATWORMS

69.4

[TO INVERTEBRATES [ DETRITUS

Fig. 4. Pie diagrams showing average proportion of alimentary tracts filled with each food item. Numbers under diagrams are average percentage fullness of tracts.

in 9 of 12 populations was detritus, with invertebrates occasionally a major food item in summer or autumn. Other categories were sparsely and intermittently represented.

The amount of each food item as a percentage of total food in guts is a better indicator of actual food choice by G. marshi (Table 1) since it ignores empty portions of the digestive tract. Detritus constituted 37 to 90% of the diet, while invertebrates made up 9 to nearly 60%. No seasonal trends were obvious other than an increase in utilization of invertebrates through the year in lagunas. Overall food choice was remarkably similar in lagunas and rivers, two natural habitats, while detritus was more im- portant in the artificial canal (Table 1). Inver- tebrate prey were identified whenever possible and at least 12 taxa were utilized: Platyhel- minthes (Planariidae), Arthropoda (Arachnida, Ostracoda, unidentified crustaceans), Insecta (Ephemeroptera, Odonata, Megaloptera, He- miptera [Corixidae, Naucoridae], Coleoptera, Diptera, Hymenoptera [red ants]).

Fishes as prey items were detected only from lagunas and rivers and in quantifiable amounts only in summer and autumn (Fig. 4). Based on scale structure and pigmentation patterns, fish eaten were almost certainly juvenile G. marshi.

Although the species is thus cannibalistic the behavior appears to be rare.

Parasites. -Four parasite species were collected from G. marshi: an intestinal trematode, a small (5-10 mm) intestinal nematode, a large (20-100 mm) encysted coelomic nematode (possibly Con- tracaecum sp.), all unidentified and an acanthocephalan of the genus Paulisentis (Hoffman, 1967). Incidences of parasitism by season and habitat (Table 2) indicate more heavily infected fish in lagunas and lowest incidence of parasitism in the canal. The small nematode, when present, often numbered several to 20 individuals per fish; other parasites generally occurred singly. The only other report of G. marshi parasites is by Guajardo-Martinez (1984) who found "... encysted and intestinal nematodes ...."

DISCUSSION

G. marshi is an abundant fish in the Cuatro Cienegas basin and adjacent drainages (Minck- ley, 1962, 1969, 1984). It tolerates a wide range of environmental conditions and adapts to a variety of situations, with relatively little effect on life history parameters. The fish is by all mea- sures a generalist, feeding on a variety of items

SPRING SUMMER FALL

70.8

83.8

902



TABLE 1. PERCENTAGE OF Gambusia marshi DIET CONSISTING OF EACH FOOD CATEGORY, LISTED BY HABITAT AND SEASON.

Habitat Season Detritus Invertebrates Flatworms Plants Fish

Laguna Winter 90.3 8.9 0 0.8 tr Spring 52.4 46.9 0.70 0 Summer 40.1 50.3 0 0 9.6 Autumn 37.7 59.1 0 1.6 1.6

Mean 55.1 41.3 0.2 0.6 2.8 River Winter 57.9 42.1 0 0 0

Spring 52.8 41.5 0 5.7 0 Summer 42.8 54.2 0 1.5 1.5 Autumn 76.3 21.0 0 2.7 0

Mean 57.4 39.7 0 2.5 0.4 Canal Winter 76.6 22.3 1.1 0 0

Spring 90.5 9.3 0.2 0 0 Summer 77.5 18.7 0.3 3.5 0 Autumn 83.1 10.6 1.3 5.0 0

Mean 81.9 15.3 0.7 2.1 0 Grand mean 64.8 32.1 0.3 1.7 1.1

and existing in all major habitats of Cuatro Cie- negas, from natural streams, marshes and lakes to artificial canals.

Fish from three habitats exhibited similar patterns with respect to reproductive activities, but with slightly different lengths of reproductive season. Reproduction in lagunas began in Jan., when about one-third of the females contained yolked ova or early embryos (Fig. 1). Repro- duction was at a peak through autumn (Sept.) and presumably declined thereafter. The reproductive season in lagunas apparently spans 9+ months.

Fish in rivers were reproductively inactive in Dec. except for one individual beginning to yolk ova and another with early embryos. Most fish

were reproducing in spring and summer (Fig. 1), while only half remained active in Sept. Riv- er fish also appear to be reproductively active from Jan.-Sept. but with smaller broods at the beginning and end of the season.

Fish in the canal were all inactive near the end of Jan., while full reproductive activity occurred through spring and summer (Fig. 1). By mid-Aug. reproduction was on the decline, with about two-thirds of the fish no longer carrying offspring. Reproductive season in the canal was shorter than elsewhere, probably lasting from Feb. or March until Aug.

Overall, fish were reproductively active long- est and carried the largest broods in lagunas, while both parameters were depressed in the

TABLE 2. PARASITES COLLECTED FROM Gambusia marshi AT CUATRO CIENEGAS. Total number of fishes examined is in parentheses, below which is number of individuals infected by trematode, small nematode, large

nematode and acanthocephalan parasites, respectively.

Season

Winter Spring Summer Autumn

Lagunas (25) (32) (20) (18) 8,0,0,0 1,0,0,0 4, 13,0,0 0,0,0, 1

Rivers (18) (11) (24) (23) 0,0, 1 0,0, 0,0,0 0,9,0,0 1,00,0,0

Canal (26) (25) (25) (27) 0,,0,00 0,0,0,0 0,0,0,0 1,0,3,0

903


COPEIA, 1985, NO. 4

canal. This is curious since fish in canals had the highest average slope for SCF (.0283 vs .0274 and .0233 for lagunas and rivers, respectively) and thus were not in poor somatic condition. Reproduction in G. marshi is probably not primarily limited by energetic contraints, but is rather a function of local environmental conditions.

SCF's were remarkably consistent among seasons and habitats (Fig. 3). Other than minor mean differences just mentioned (not statistically significant) there was no clear evidence of seasonal or habitat effects on robustness and most fish examined appeared to be in good condition. There was, however, an unmeasured seasonal effect on amount of fat present. Vis- ceral fat was generally absent or at low levels in reproductively active females (spring and summer) and was prevalent along the alimentary tracts in autumn and winter. Storage apparently begins when reproduction declines making high- energy fats available for the next reproductive season.

Patterns of RE were erratic, but generally paralleled total reproduction. In most cases, RE increased with SL, although this was not always significant (Fig. 2). RE was generally less dependent upon SL than was total reproduction, indicating that energetic commitments to reproduction in G. marshi may be flexible.

Life history patterns of G. marshi are typical of gambusiines in general (Krumholz, 1948, 1963; Hubbs and Springer, 1957; Hubbs, 1971; Peden, 1973). Most examined to date repro- duce seasonally, are generalists in food choice and exhibit increased fecundity with increased female size. Gambusia marshi is more of a habitat generalist than species such as G. amistadensis (Peden, 1973), G. gaigei (Hubbs and Brodrick, 1963), G. geiseri (Hubbs and Springer, 1957), G. georgei (Hubbs and Peden, 1969), G. heterochir (Hubbs, 1957), G. krumholzi (Minckley, 1963) or G. longispinis (Minckley, 1962), which are re- stricted to limited habitats or are otherwise rare in Coahuila or adjacent southern Texas, but probably is not as generalized as the cosmopol- itan G. affinis. The apparently flexible nature of G. marshi is likely responsible for its abundance within its limited geographic range.

ACKNOWLEDGMENTS

W. L. Minckley's pioneering studies of the Cuatro Cienegas fauna made this analysis possible. I thank him for introducing me to this

amazing region, for allowing me to exploit hard- earned specimens collected by himself, his col- leagues and students and for critically reviewing the manuscript. The paper was improved by the comments of Clark Hubbs and an anonymous reviewer. Financial support during analysis of fishes was provided by the Department of Zo- ology, ASU; manuscript preparation was aided by a postdoctoral appointment at the University of Florida. I thank Grace Kiltie for typing the manuscript and B. DeMarias for assistance in data analysis.

LITERATURE CITED

ARNOLD, E. T. 1966. Comparative studies of mating behavior in gambusiin fishes (Cyprinodontiformes: Poeciliidae). Unpubl. MS Thesis, Arizona State University, Tempe, Arizona.

CAMPOS, H. H., AND C. HUBBS. 1971. Cytomor- phology of six species of gambusiine fishes. Copeia 1971:566-569.

CONTRERAS-BALDERAS, S. 1984. Environmental im- pacts in Cuatro Ci6negas, Coahuila, Mexico: a com- mentary. J. Ariz.-Nev. Acad. Sci. 19:85-88.

DIXON, W. J., M. B. BROWN, L. ENGELMAN, J. W. FRANE, M. A. HILL, R. I. JENNRICH AND J. D. TOPOREK. 1981. BMDP statistical software. Uni- versity of California Press, Berkeley, California.

GUAJARDO-MARTINEZ, G. 1984. Preliminary survey of parasites of Cuatro Ci6negas, Coahuila, Mexico. J. Ariz.-Nev. Acad. Sci. 19:81-83.

HOFFMAN, G. L. 1967. Parasites of North American freshwater fishes. University of California Press, Berkeley, California.

HUBBS, C. 1957. Gambusia heterochir, a new poeciliid fish from Texas, with an account of its hybridization with G. affinis. Tulane Stud. Zool. 5:1-16.

1971. Competition and isolation mechanisms in the Gambusia affinis x G. heterochir hybrid swarm. Bull. Tex. Mem. Mus. 19:1-47.

, AND H. J. BRODRICK. 1963. Current abundance of Gambusia gaigei, an endangered fish species. Southwest. Natur. 8:46-48.

, AND A. E. PEDEN. 1969. Gambusia georgei sp. nov. from San Marcos, Texas. Copeia 1969:357- 364.

,AND V. G. SPRINGER. 1957. A revision of the Gambusia nobilis species group, with descriptions of three new species, and notes on their variation, ecology, and evolution. Tex. J. Sci. 9:279-327.

KRUMHOLZ, L. A. 1948. Reproduction in the western mosquito fish, Gambusia affinis affinis (Baird and Gi- rard), and its use in mosquito control. Ecol. Mono- gr. 18:1-43.

. 1963. Relationships between fertility, sex ra- tio, and exposure to predation in populations of the mosquitofish Gambusia manni Hubbs at Bimini, Ba- hamas. Int. Revue ges. Hydrobiol. 48:201-256.

904


MEFFE-GAMBUSIA MARSHI LIFE HISTORY MEFFE-GAMBUSIA MARSHI LIFE HISTORY

MARSH, P. C. 1984. Proceedings of the symposium on the Cuatro Cienegas of Coahuila, Mexico. J. Ariz.-Nev. Acad. Sci. 19:1-2.

MINCKLEY, W. L. 1962. Two new species of fishes of the genus Gambusia (Poeciliidae) from northeastern Mexico. Copeia 1962:391-396.

. 1963. A new poeciliid fish (genus Gambusia) from the Rio Grande drainage of Coahuila, Mexico. Southwest. Natur. 8:154-161.

. 1964. Hybridization of two species of mos- quitofishes (Gambusia, Poeciliidae) in the laboratory. J. Ariz. Acad. Sci. 3:87-89.

1969. Environments of the Bolson of Cuatro Cienegas, Coahuila, Mexico. With special reference to the aquatic biota. Texas Western Press, Univer- sity of Texas Press, El Paso, Texas.

. 1984. Cuatro Cienegas fishes: research review and a local test of diversity versus habitat size. J. Ariz.-Nev. Acad. Sci. 19:13-21.

MARSH, P. C. 1984. Proceedings of the symposium on the Cuatro Cienegas of Coahuila, Mexico. J. Ariz.-Nev. Acad. Sci. 19:1-2.

MINCKLEY, W. L. 1962. Two new species of fishes of the genus Gambusia (Poeciliidae) from northeastern Mexico. Copeia 1962:391-396.

. 1963. A new poeciliid fish (genus Gambusia) from the Rio Grande drainage of Coahuila, Mexico. Southwest. Natur. 8:154-161.

. 1964. Hybridization of two species of mos- quitofishes (Gambusia, Poeciliidae) in the laboratory. J. Ariz. Acad. Sci. 3:87-89.

1969. Environments of the Bolson of Cuatro Cienegas, Coahuila, Mexico. With special reference to the aquatic biota. Texas Western Press, Univer- sity of Texas Press, El Paso, Texas.

. 1984. Cuatro Cienegas fishes: research review and a local test of diversity versus habitat size. J. Ariz.-Nev. Acad. Sci. 19:13-21.

PEDEN, A. E. 1972a. Differences in the external gen- italia of female gambusiin fishes. Southwest. Natur. 17:265-272.

1972b. The function of gonopodial parts and behavioral pattern during copulation by Gambusia (Poeciliidae). Canad. J. Zool. 50:955-968.

. 1973. Virtual extinction of Gambusia amistadensis n. sp., a poeciliid fish from Texas. Copeia 1973:210-221.

TAYLOR, D. W., AND W. L. MINCKLEY. 1966. New world for biologists. Pacific Discov. 19:18-22.

DEPARTMENT OF ZOOLOGY, ARIZONA STATE UNIVERSITY, TEMPE, ARIZONA 85287. PRES- ENT ADDRESS: SAVANNAH RIVER ECOLOGY LABORATORY, DRAWER E, AIKEN, SOUTH CAROLINA 29801. Accepted 26 Feb. 1985.

PEDEN, A. E. 1972a. Differences in the external gen- italia of female gambusiin fishes. Southwest. Natur. 17:265-272.

1972b. The function of gonopodial parts and behavioral pattern during copulation by Gambusia (Poeciliidae). Canad. J. Zool. 50:955-968.

. 1973. Virtual extinction of Gambusia amistadensis n. sp., a poeciliid fish from Texas. Copeia 1973:210-221.

TAYLOR, D. W., AND W. L. MINCKLEY. 1966. New world for biologists. Pacific Discov. 19:18-22.

DEPARTMENT OF ZOOLOGY, ARIZONA STATE UNIVERSITY, TEMPE, ARIZONA 85287. PRES- ENT ADDRESS: SAVANNAH RIVER ECOLOGY LABORATORY, DRAWER E, AIKEN, SOUTH CAROLINA 29801. Accepted 26 Feb. 1985.

Copeia, 1985(4), pp. 905-910

An Experimental Demonstration of the Species-Recognition Role of Anolis Dewlap Color

JONATHAN B. Losos

Inter- and intraspecific encounters were staged in the laboratory between adult males of the sympatric sibling species Anolis marcanoi and A. cybotes which differ morphologically only in dewlap color. Levels of intraspecific aggression among A. marcanoi were high, but little interspecific aggressive behavior was observed. The importance of dewlap color for species-recognition was assessed by changing the color of the dewlap of A. marcanoi to appear like that of A. cybotes and vice- versa. A. marcanoi in interspecific encounters between altered individuals exhibited an intermediate level of aggressive behavior. Intraspecific encounters between pairs of A. marcanoi with altered dewlaps revealed no higher level of aggression than the normal interspecific encounters. A system of species-recognition signals is proposed in which lizards examine more obvious signals, such as dewlap color, at greater distances and more subtle signals, such as head- bobbing patterns, at closer distances.

Copeia, 1985(4), pp. 905-910

An Experimental Demonstration of the Species-Recognition Role of Anolis Dewlap Color

JONATHAN B. Losos

Inter- and intraspecific encounters were staged in the laboratory between adult males of the sympatric sibling species Anolis marcanoi and A. cybotes which differ morphologically only in dewlap color. Levels of intraspecific aggression among A. marcanoi were high, but little interspecific aggressive behavior was observed. The importance of dewlap color for species-recognition was assessed by changing the color of the dewlap of A. marcanoi to appear like that of A. cybotes and vice- versa. A. marcanoi in interspecific encounters between altered individuals exhibited an intermediate level of aggressive behavior. Intraspecific encounters between pairs of A. marcanoi with altered dewlaps revealed no higher level of aggression than the normal interspecific encounters. A system of species-recognition signals is proposed in which lizards examine more obvious signals, such as dewlap color, at greater distances and more subtle signals, such as head- bobbing patterns, at closer distances.

THE sibling species Anolis marcanoi and A. cybotes are trunk-ground ecomorphs (Wil-

liams, 1972) found sympatrically throughout much of A. marcanoi's limited range in south- western Dominican Republic. They are consis- tently separable morphologically only by the color of the dewlap of males and the throat of females: red in A. marcanoi, yellow or white in A. cybotes (Williams, 1975). Electrophoretic studies, however, show them to be quite distinct and reveal no hybrids (Webster, 1975). How the species coexist is a puzzle. In some areas, they

THE sibling species Anolis marcanoi and A. cybotes are trunk-ground ecomorphs (Wil-

liams, 1972) found sympatrically throughout much of A. marcanoi's limited range in south- western Dominican Republic. They are consis- tently separable morphologically only by the color of the dewlap of males and the throat of females: red in A. marcanoi, yellow or white in A. cybotes (Williams, 1975). Electrophoretic studies, however, show them to be quite distinct and reveal no hybrids (Webster, 1975). How the species coexist is a puzzle. In some areas, they

are found on adjacent fenceposts (Hertz, 1980), whereas in other localities only one species is present. Although Hertz (1980) suggests that A. marcanoi may be adapted to hotter, more open microhabitats, field observations have failed to discover any obvious difference (Wil- liams, 1975; Hertz, 1980; pers. obs.). The ex- istence of two such closely related species in sympatry raises two questions amenable to laboratory investigation: does interspecific terri- torial behavior occur and, if not, how do males distinguish conspecifics from non-conspecifics?

are found on adjacent fenceposts (Hertz, 1980), whereas in other localities only one species is present. Although Hertz (1980) suggests that A. marcanoi may be adapted to hotter, more open microhabitats, field observations have failed to discover any obvious difference (Wil- liams, 1975; Hertz, 1980; pers. obs.). The ex- istence of two such closely related species in sympatry raises two questions amenable to laboratory investigation: does interspecific terri- torial behavior occur and, if not, how do males distinguish conspecifics from non-conspecifics?

? 1985 by the American Society of Ichthyologists and Herpetologists ? 1985 by the American Society of Ichthyologists and Herpetologists

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Article Contentsp.898p.899p.900p.901p.902p.903p.904p.905

Issue Table of ContentsCopeia, Vol. 1985, No. 4, Dec. 10, 1985Volume Information [pp.1119-1144]Front MatterContributions of Developmental Characters to a Phylogeny of Catostomid Fishes, with Comments on Heterochrony [pp.833-846]Larval Periods, Population Structure and the Effects of Stream Drift in Larvae of the Salamanders Desmognathus quadramaculatus and Leurognathus marmoratus in a Southern Appalachian Stream [pp.847-854]Morphological Differentiation of Etheostoma olmstedi and E. nigrum (Pisces: Percidae) in Canada [pp.855-865]Eptatretus mendozai, A New Species of Hagfish (Myxinidae) from off the Southwest Coast of Puerto Rico [pp.865-869]The Systematics and Distribution of the Lophiid Anglerfishes: III. Intergeneric Relationships [pp.870-875]Wound Healing: A Possible Role of Cleaning Stations [pp.875-880]Growth of the Mountain Brook Lamprey Ichthyomyzon greeleyi Hubbs and Trautman [pp.881-890]Geographic Variation in the Milkfish Chanos chanos II. Multivariate Morphological Evidence [pp.890-898]Life History Patterns of Gambusia marshi (Poeciliidae) from Cuatro Cinegas, Mexico [pp.898-905]An Experimental Demonstration of the Species-Recognition Role of Anolis Dewlap Color [pp.905-910]A New Species of Atelopus (Anura, Bufonidae) from the Andes of Northern Per [pp.910-917]Individual and Temporal Variation in Prey Switching by Brown Trout, Salmo trutta [pp.918-926]Facultative Metamorphosis in a Series of High Altitude Fossil Populations of Ambystoma tigrinum (Irvingtonian: Alamosa County, Colorado) [pp.926-932]Differences in Aggressive Behavior between Two Throat Color Morphs in a Lizard, Urosaurus ornatus [pp.933-940]Female Reproductive Cycle and Life History Attributes in a Virginia Population of Stinkpot Turtles, Sternotherus odoratus [pp.941-949]Reproduction and Growth of Typhlonectes compressicaudus: A Viviparous Gymnophione [pp.950-955]Population Size Estimates for a Marine Snake (Enhydrina schistosa) in Malaysia [pp.955-961]The Effect of Low-Latitude Photoperiods on the Reproduction of Female and Male Poeciliopsis gracilis and Poecilia sphenops [pp.961-965]Social Behavior and Coloration Changes in Painted Greenling, Oxylebius pictus (Pisces: Hexagrammidae) [pp.966-975]Reproduction in the Collared Lizard, Crotaphytus collaris, in West Central Texas [pp.976-980]Drinking of Soil Water by the California Legless Lizard, Anniella pulchra [pp.981-986]Age-Related Dietary Patterns of Sympatric Adult Surfperch [pp.986-994]Pangasius sutchi (Pangasiidae), an Air-Breathing Catfish That Uses the Swimbladder as an Accessory Respiratory Organ [pp.994-998]Variation in the Degree of Viviparity in the Sailfin Molly, Poecilia latipinna [pp.999-1004]Ontogenetic Change in Phototactic Responses of Surface and Cave Populations of Astyanax fasciatus (Pisces: Characidae) [pp.1004-1011]Depth-Related Changes in Sagitta Morphology in Six Macrourid Fishes of the Pacific and Atlantic Oceans [pp.1011-1017]Functional Morphology of the Branchial Basket Structures Associated with Feeding in the Atlantic Menhaden, Brevoortia tyrannus (Pisces: Clupeidae) [pp.1018-1027]Maternal Influences on Offspring Development in the California Newt, Taricha torosa [pp.1028-1035]Polychromatism and Polymorphism in Breviraja spinosa (Elasmobranchii, Rajiformes), with Description of Three New Species [pp.1035-1052]Ichthyological NotesA Unique Gambusiine Karyotype and Its Relevance to the Systematics of the Gambusia punctata Species Group [pp.1053-1056]Variation in Mitochondrial DNA Genome Size among Fishes of the Family Scorpaenidae [pp.1056-1058]Cheirodon arnoldi, a Senior Synonym of Cheirodon affinis, a Common Panamanian Characid Fish (Teleostei, Ostariophysi) [pp.1058-1060]Individual Recognition in the Juvenile Brown Bullhead (Ictalurus nebulosus) [pp.1060-1062]Fecundity of Gambusia gaigei [pp.1063-1064]Serranus lamprurus Jordan and Gilbert, 1882 (Pisces: Serranidae), a Junior Synonym of Lutjanus argentiventris (Peters, 1869) (Pisces: Lutjanidae) [pp.1064-1066]

Herpetological NotesPrey Constriction by Venomous Snakes: A Review, and New Data on Australian Species [pp.1067-1071]Differentiation in Amount of Centromeric Heterochromatin between Subspecies of the Redlegged Frog, Rana aurora [pp.1071-1074]The Effect of Tail Autotomy on the Exercise Capacity of the Water Skink, Sphenomorphus quoyii [pp.1074-1077]Maximum Prey Size of an Insectivorous Lizard, Sceloporus undulatus garmani [pp.1077-1080]Does Age-Specific Mortality Decrease with Age in Amphibian Larvae? [pp.1080-1083]Seasonal Variation in Clutch Size for Loggerhead Sea Turtles, Caretta caretta, Nesting on Little Cumberland Island, Georgia, USA [pp.1083-1085]

Reviews and Commentsuntitled [p.1086]

Editorial Notes and News [pp.1087-1090]Karl F. Lagler, 1912-1985 [pp.1090-1091]Erratum: Swimming in Constricting (Elaphe g. guttata) and Nonconstricting (Nerodia fasciata pictiventris) Colubrid Snakes [p.1091]Summary of the Meetings 1985 [pp.1092-1118]Back Matter

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