Starvation Stress and Intraovarian Cannibalism in Livebearers (Atheriniformes: Poeciliidae) Author(s): Gary K. Meffe and Robert C. Vrijenhoek Source: Copeia, Vol. 1981, No. 3 (Aug. 26, 1981), pp. 702-705 Published by: American Society of Ichthyologists and Herpetologists Stable URL: http://www.jstor.org/stable/1444578 . Accessed: 21/06/2011 17:33 Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at . http://www.jstor.org/action/showPublisher?publisherCode=asih. . Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact
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tute breeding populations. All size classes are represented in collections from the upper, high-temperature stretch of the stream. It is unlikely that individuals are moving up from cooler water downstream because the intervening course has been modified to form a swiftwater irrigation ditch which probably acts as an effective barrier. Cyprinodon sp. and Gambusia cf. senilis appeared to be in good physical condition, and large fat bodies were present in adults of both species. Gonads were examined in adult Cyprinodon and Gambusia collected over temperatures ranging from 39.2 to 43.8 C. Testes were enlarged in males of Cyprinodonand ova in various states of development were present in females of both species. In laboratory tests on Cyprinodon n. nevadensis, Shrode and Gerking (1977) found that temperature limits for egg production and maturation were narrower than limits for normal activity or for spawning and concluded that "oogenesis is the most temperaturesensitive phase of the life cycle." The presence of developing ova in females from water of 39.2-43.8 C is therefore good evidence that Cyprinodonsp. and Gambusia cf. senilis are not stressed at those temperatures, which are the highest long-term temperature tolerances known for any teleost.
1974. CraterC. J. M. GLOVER. ocephalusdalhousiensisn. sp., a sexually dimorphic freshwater teleost (Atherinidae) from South Australia. Aust. Zool. 18:88-98. MILLER,R. R. 1949. Hot springsand fish life. Aquar. J. 20:286-288.
IVANTSOFF, W., AND
OTTO, R. G., AND S. D. GERKING. 1973.
Heat toler-
ance of a Death Valley pupfish (genus Cyprinodon). Physiol. Zool. 46:43-49.
SHRODE, J. B., AND S. D. GERKING.
1977. Effects of
constant and fluctuating temperatures on reproductive performance of a desert pupfish, CyprinoIbid. 50:1-10. don n. nevadensis. 1978. The natural SOLTZ, D. L., AND R. J. NAIMAN. history of native fishes in the Death Valley system. Natural History Museum of Los Angeles County, Science Series 30. MICHAELLEONARD SMITH, Divisionof Biological Sciences and Museum of Zoology, AND BARRY
andFish CHERNOFF,Schoolof NaturalResources Division,Museumof Zoology,Universityof Michigan,AnnArbor,Michigan48109. Accepted 15 July 1980.
Copeia, 1981(3), pp. 702-705
? 1981 by the American Society of Ichthyologists and Herpetologists
STARVATION STRESS AND INTRAOVARIN LIVEBEARERS IAN CANNIBALISM (ATHERINIFORMES: POECILIIDAE).-For several decades, it has been suggested that poeciliid fishes abort and resorb developing embryos during environmental stress, implying that this may be an adaptive mechanism used to recoup energy invested into reproduction. Scrimshaw (1944) examined several species which occasionally superfetate (i.e., simultaneous development of more than one brood). In many cases, youngest broods became atretic and were resorbed. As a result of extensive LITERATURECITED morphological studies of intraovarian develBROWN, J. H. 1971. The desert pupfish. Sci. Amer. opment, Turner (1947) stated that "Many of 225:104-110. the embryos die and the bodies disintegrate. 1971. Evolutionin con, ANDC. R. FELDMETH. are either absorbed by the ovary, or the stant and fluctuating environments: thermal tol- They parts are ingested by the surviving remaining Evolution erances of desert pupfish (Cyprinodon). in a kind of intraovarian cannibalism." embryos 25:390-398. stated that "Degenerating ova Schultz (1961) DEACON, J. E., ANDW. L. MINCKLEY.1974. Desert fishes, p. 385-487. In: Desert Biology, Vol. 2. G. and embryos are common in females living under suboptimal conditions . . . ." Hester (1964) W. Brown,Jr. (ed.). Academic Press. C. R., E. A. STONEAND J. H. BROWN. applied a partial starvation stress to guppies FELDMETH, 1974. An increased scope for thermal tolerance (Poecilia reticulata) and found that "... physioto cycling logical stress might . . . cause an immediate reupon acclimating pupfish (Cyprinodon) temperature.J. Comp. Physiol.89:29-44. duction in size and number of the developing
Acknowledgments.-We extend our thanks to Robert R. Miller and Philip R. Yant for their helpful comments; and to Edie Marsh and R. R. Miller for help in the field. Field work was supported by grants from the New York Zoological Society and NSF DEB 77-17315 (to R. R. Miller). Permission to collect fishes in Mexico was kindly granted by the Direccion General de Regiones Pesqueras (permit nos. 3616 and 6243).
ICHTHYOLOGICAL NOTES large oocytes and embryos, an effect that would be revealed in the first brood after the application of stress ...." When Xiphophorusspp. are crowded in small containers and transported from Mexican streams to New York City, some field-inseminated females skip one or more initial broods when placed under optimal laboratory conditions (K. D. Kallman, pers. comm.). Borowsky and Kallman (1976) state "It is possible that the stress of collecting adversely affected the reproductive performance of the females. [Some] broods were "missed" or aborted . .. suggest[ing] that the cyclic pattern of reproduction was disrupted. We take this as further evidence of the traumatic effects of collection." We have observed the same phenomenon with Poeciliopsis spp. transported from northwestern Mexico to New Jersey. Despite these accounts of missed broods, detailed studies of resorption phenomena have yet to be undertaken. It is the purpose of this work to examine resorption more closely and to determine if it occurs at a frequency high enough to be considered adaptive response to stressful environments. Three poeciliid species were utilized, representing a wide range of reproductive adaptations and habitat types (Thibault and Schultz, 1978). Poeciliopsis monacha Miller were laboratory stocks originally collected in 1978 from the Arroyos de Guiracoba and de Jaguari of the Rio del Fuerte in Sonora, Mexico. Poeciliopsis prolifica Miller were laboratory stocks collected in 1978 in the Arroyo del Aguajita of the Rio Mayo in Sonora. Systematic inbreeding was avoided in both stocks. Poecilia reticulata Peters were obtained at local tropical fish outlets. Although "fancy" inbred strains of this species were avoided, origins and specific histories of stocks are unknown, and caution should be exercised in extrapolation of their results to wild populations. Separate populations of each species were established in 37.8-1 aquaria. Filtration was provided by one charcoal/floss filter and air stone per tank, and a 15:9 hour light:dark photoperiod was established. Average temperature was 27 C, but fluctuated somewhat between extremes of 21 C and 29 C. Plant cover was provided by the filamentous algae Pithophora kewensis, and a population of 10 to 20 snails of the genus Planorbus was introduced into each tank. A layer of marble chips added substrate heterogeneity. Fish were fed ad libidum twice dai-
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ly, with an alternation of frozen brine shrimp and powdered Purina Trout Chow. Twentyfive female and seven male P. reticulata were used, as were 23 female and eight male P. monacha and 23 female and six male P. prolifica. They remained in these "conditioning tanks" for several weeks, after which the length of each female was measured to the nearest millimeter. They were then weighed to the nearest thousandth of a gram on a Sartorius balance in a tared beaker of water. A condition factor [(weight/length) x 100] (modified from Lagler et al., 1977) was calculated for each fish, which is used as an index of robustness for the individual-the higher the factor, the more robust the fish. These measurements were not taken for P. reticulata. After weighing, the entire population of each species was placed into clean 20.8-1 aquaria with normal filtration but with no algal growth, snails or vascular plants. The fish were never fed after this, and the filter was cleaned frequently to remove algal growth. This treatment thus provided stress by starvation and crowding (the density was doubled by halving the tank size). Two females were removed every three to five days, and length and weight measurements of these were again taken; the fish were then sacrificed by immersion in ice water. Each ovary was examined under a dissecting microscope, contents removed and all embryos inspected for degeneration or abnormalities of body parts. Each population was treated as such for approximately 30 days, until all females were examined. The condition factors of pre-stressed and starved populations of fish were compared in a test of the null hypothesis that starvation stress had no effect on the fish. Condition factors of pre-stressed fish were compared to those of stressed fish in a Student's "t" test. The stressed population consisted of a serial sampling of individuals in various stages of starvation, and therefore included fish that had experienced stress for only a short period. This would decrease the power of the test (probability of rejecting a false null hypothesis). Even with this bias, both P. monacha and P. prolifica demonstrated a significant weight loss during starvation [P. monacha: tdf= 44 = 2.02, P < .05; P. prolifica: tdf=44 = 8.78, P
