許多研究發現獲勝經驗使動物在後續打鬥時有較高的攻擊性及獲勝機率 (勝者效應，winner effect)，落敗經驗則有相反的影響 (敗者效應，loser effect)。相較於敗者效應，勝者效應通常較不易偵測到，使得研究勝者效應的生理機制較為困難。睪固酮 (testosterone) 及皮質醇 (cortisol) 是與打鬥行為有密切相關的固醇類荷爾蒙，經常伴隨著動物的獲勝或落敗而變化，因此被推測可能是獲勝經驗調控後續打鬥行為的生理機制之一。雌雄同體且行自體授精的紅樹林鱂魚Kryptolebias marmoratus (former : Rivulus marmoratus) 具有顯著的勝者效應，而且打鬥行為與體內的睪固酮及皮質醇濃度有關聯性，是研究勝者效應與荷爾蒙關係的合適物種。本研究透過強制給予K. marmoratus個體連續三次的獲勝經驗，探討獲勝經驗前後個體體內睪固酮及皮質醇濃度是否有顯著改變，以及經驗後睪固酮及皮質醇濃度是否對後續打鬥的行為及勝率有顯著影響。此外，本研究亦探討K. marmoratus個體得到獲勝經驗後，再次參與打鬥時與對手的互動、打鬥結果以及經驗後荷爾蒙濃度，是否影響其打鬥後的體內荷爾蒙濃度。結果顯示，連續三次的獲勝經驗顯著地提高個體率先展示、率先攻擊、率先鰓蓋展示及獲勝的機率。然而，獲勝經驗前後，K. marmoratus體內睪固酮及皮質醇濃度沒有顯著的改變。經驗後睪固酮及皮質醇濃度亦未對後續的打鬥行為造成顯著的影響。然而，打鬥後荷爾蒙濃度卻受到後續打鬥時與對手的互動及打鬥結果的影響：相較於在後續打鬥中落敗的個體，打鬥後獲勝個體有顯著較高的睪固酮及顯著較低的皮質醇濃度。根據本研究的結果，獲勝經驗應非透過改變K. marmoratus個體體內睪固酮及皮質醇的濃度以引發勝者效應。本論文並針對其他可能與勝者效應相關之生理機制如血清素(serotonin)、或其他荷爾蒙等進行討論。

Recent winning and losing experiences have been found to increase and decrease an individual’s aggressiveness and probability of winning a subsequent contest, respectively (winner and loser effect). It is harder to find a suitable organism to investigate the physiological mechanisms of the winner effect because it is not as common as the loser effect. Testosterone and cortisol have been shown to correlate with contest behavior and outcome in many animal species and are thus considered possible candidates for the physiological mechanisms underlying winner and loser effect. K. marmoratus displays both winner and loser effects and its contest behaviors correlate with its testosterone and cortisol levels, which makes the fish ideal for investigating the relationship between the winner effect and the two hormones. I gave individuals of the fish three winning experiences to investigate whether testosterone and cortisol played important roles in mediating the winner effect in the fish. The results of the study showed that the winning experiences did not have significant effects on post-experience testosterone or cortisol levels, and that post-experience testosterone and cortisol levels did not have significant relationships with the fish’s subsequent contest behavior or outcome. Interestingly, the fish’s subsequent contest behavior and outcome appeared to influence its post-contest testosterone and cortisol levels: winners of the subsequent contests had higher testosterone but lower cortisol levels than the losers. I concluded from these results that although these two hormones may have important relationships with the fish’s contest behavior, they are not responsible for mediating the winner effect in the fish. Physiological mechanisms that might be important to the winner effect of the fish are discussed.

Adams, C. E., Huntingford, F. A., Turnbull, J. F. and Beattie, C. 1998. Alternative competitive strategies and the cost of food acquisition in juvenile Atlantic salmon (Salmo salar). Aquaculture 167: 17-26

Beacham, J. L. and Newman, J. A. 1987. Social experience and the formation of dominance relationships in the pumpkinseed fish, Lepomis gibbosus. Animal Behaviour 35: 1560-1563

Beacham, J. L. 2003. Models of dominance hierarchy formation: Effects of prior experience and intrinsic traits. Behaviour 140: 1275-1303

Beaugrand, J. P., Goulet, C. and Payette, D. 1991. Outcome of dyadic conflict in male green swordtail fish,Xiphophorus helleri: Effects of body size and prior dominance. Animal Behaviour 41: 417-424

Beaugrand, J. P. and Goulet, C. 2000. Distinguishing kinds of prior dominance and subordination experiences in males of green swordtail fish (Xiphophorus helleri). Behavioural Processes 50: 131-142

Bégin, J., Beaugrand, J. P. and Zayan, R. 1996. Selecting dominants and subordinates at conflict outcome can confound the effects of prior dominance or subordination experience. Behavioural Processes 36: 219-226

Bentvelsen, F. M., Brinkmann, A. O., Van der Schoot, P., Van der Linden, J. E. T. M., Van der Kwast, Th. H., Boersma, W. J. A., Schröder, F. H. and Nijman, J. M. 1995. Developmental pattern and regulation by androgens of androgen receptor expression in the urogenital tract of the rat. Molecular and Cellular Endocrinology 113: 245-253

Bergman, D. A., Kozlowski, C. P., Mcintyre, J. C., Huber, R., Daws, A. G. and Moore, P. A. 2003. Temporal dynamics and communication of winner-effects in the crayfish, Orconectes rusticus. Behaviour 140: 805-825

Berthold, A. A. 1849. Transplantation of testes. (English translation by D. P. Quiring, 1944) Bulletin of the History of Medicine 16: 399-401

Bevan, W., Daves, W. F. and Levy, G. W. 1960. The relation of castration, androgen therapy and pre-test fighting experience to competitive aggression in male C57 BL/10 mice. Animal Behaviour 8: 6-12

Castro, N., Ros, A. F. H., Becker, K. and Oliveira, R. F. 2006. Metabolic costs of aggressive behaviour in the Siamese fighting fish, Betta splendens. Aggressive Behavior 32: 474-480

Chase, I. D., Bartolomeo, C. and Dugatkin, L. A. 1994. Aggressive interactions and inter-contest interval: how long do winners keep winning. Animal Behaviour 48: 393-400

Consten, D., Lambert, J. G. D. and Goos, H. J. Th. 2001. Cortisol affects testicular development in male common carp, Cyprinus carpio L., but not via an effect on LH secretion. Comparative Biochemistry and Physiology part B:
Biochemistry and Molecular Biology 129: 67-677

Costa, W. J. E. M. 2004. Kryptolebias, a substitute name for Cryptolebias Costa, 2004 and Kryptolebiatinae, a substitute name for Cryptolebiatinae Costa, 2004 (Cyprinodontiformes: Rivulidae). Neotropical Ichthyology 2: 107-108

Diaz-Uriarte, R. 1999. Anti-predator behaviour changes following an aggressive encounter in the lizard Tropidurus hispidus. Proceedings of the Royal Society of London, Series B 266: 2457-2464

Drummond, H. and Canales, C. 1998. Dominance between booby nestlings involves winner and loser effects. Animal Behaviour 55: 1669-1676

Earley, R. L., Edwards, J. T., Aseem, O., Felton, K., Blumer, L. S., Karom, M. and Grober, M. S. 2006. Social interactions tune aggression and stress responsiveness in a territorial cichlid fish (Archocentrus nigrofasciatus).
Physiology & Behavior 88: 353-363

Earley, R. L. and Hsu, Y. Y. 2008. Reciprocity between endocrine state and contest behavior in the killifish, Kryptolebias marmoratus. Hormones and Behavior 53: 442-451

Elofsson, U. O., Mayer, I., Damsgård, B. and Winberg, S. 2000. Intermale competition in sexually mature arctic charr: effects on brain monoamines, endocrine stress responses, sex hormone levels, and behavior. General and
Comparative Endocrinology 118: 450-460

Enquist, M. and Leimar, O. 1983. Evolution of fighting behaviour: decision rules and assessment of relative strength. Journal of Theoretical Biology 102: 387-410

Enquist, M. and Leimar, O. 1987. Evolution of fighting behaviour: the effect of variation in resource value. Journal of Theoretical Biology 127: 187-205.

Enquist, M., Leimar, O., Ljungberg, T., Mallner, Y. and Segerdahl, N. 1990. A test of the sequential assessment game: fighting in the cichlid fish Nannacara anomala. Animal Behaviour 40: 1-14.

Farrell, W. and Wilczynski, W. 2006. Aggressive experience alters place preference in green anole lizards, Anolis carolinensis. Animal Behaviour 71:1155-1164

Fuxjager, M. J., Mast, G., Becker, E. A. and Marler, C. A. 2009. The ‘home advantage’ is necessary for a full winner effect and changes in post-encounter testosterone. Hormones and Behavior 56: 214-219

Goymann, W., Landys, M. M. and Wingfield, J. C. 2007. Distinguishing seasonal androgen responses from male–male androgen responsiveness— Revisiting the Challenge Hypothesis. Hormones and Behavior 51: 463-476

Hack, M. A. 1997. The energetic costs of fighting in the house cricket, Acheta domesticus L.. Behavioral Ecology 8: 28-36

Hammerstein, P. and Parker, G. A. 1982. The asymmetric war of attrition. Journal of Theoretical Biology 96: 647-682

Harrington, R. W., Jr. 1961. Oviparous hermaphroditic fish with internal self-fertilization. Science 134: 1749-1750

Harrington, R. W., Jr. 1963. Twenty-four-hour rhythms of internal self-fertilization and of oviposition by hermaphrodites of Rivulus marmoratus. Physiological Zoology 36: 325-341

Hirschenhauser, K., Taborsky, M., Oliveira, T., Canàrio, A. V. M. and Oliveira, R. F. 2004. A test of the ‘challenge hypothesis’ in cichlid fish: simulated partner and territory intruder experiments. Animal Behaviour 68: 741-750

Hirschenhauser, K. and Oliveira, R. F. 2006. Social modulation of androgens in male vertebrates: Meta-analyses of the challenge hypothesis. Animal Behaviour 71: 265-277

Hock, K. and Huber, R. 2009. Models of winner and loser effects: A cost-benefit analysis. Behaviour 146: 69-87

Hollis, K. L. 1984. The biological function of Pavlovian conditioning: The best defense is a good offense. Journal of Experimental Psychology: Animal Behavior Processes 10: 413-425

Hollis, K. L. 1999. The role of learning in the aggressive and reproductive behavior of blue gouramis, Trichogaster trichopterus. Environmental Biology of Fishes 54: 355-369

Hsu, Y. Y. and Wolf, L. L. 1999. The winner and loser effect: Integrating multiple experiences. Animal Behaviour 57: 903-910

Hsu, Y. Y. and Wolf, L. L. 2001. The winner and loser effect: What fighting behaviours are influenced? Animal Behaviour 61: 777-786

Hsu, Y. Y., Earley, R. L. and Wolf, L. L. 2006. Modulation of aggressive behaviour by fighting experience: Mechanisms and contest outcomes. Biological Reviews 81: 33-74

Hsu, Y. Y., Lee, S. P., Yang, S. Y. and Cheng, K. C. 2008. Switching assessment strategy during a contest: Fighting in killifish Kryptolebias marmoratus. Animal Behaviour 75: 1641-1649

Hsu, Y. Y., Lee, I. H. and Lu, C. K. 2009. Prior contest information: mechanisms underlying winner and loser effects. Behavioral Ecology and Sociobiology 63: 1247-1257

Huber, R. and Delago, A. 1998. Serotonin alters decisions to withdraw in fighting crayfish, Astacus astacus: The motivational concept revisited. Journal of Comparative Physiology A 182: 573-583

Jennions, M. D. 1996. Residency and size affect fight duration and outcome in the fiddler crab Uca annulipes. Biological Journal of the Linnean Society 57: 293-306

Kruk, M. R., Halász, J., Meelis, W. and Haller, J. 2004. Fast positive feedback between the adrenocortical stress response and a brain mechanism involved in aggressive behavior. Behavioral Neuroscience 118: 1062-1070

Lee, I. H. 2009. The hormonal mechanisms of the loser effect in Kryptolebias marmoratus. Master’s thesis. Taipei, Taiwan: National Taiwan Normal University

Leshner, A. I. 1983. The hormonal responses to competition and their behavioral significance. Hormones and Aggressive Behaviour (ed. by Svare, B. B.)New York Plenum press: 393-404

Mackiewicz, M., Tatarenkov, A., Taylor, D. S., Turner, B. J. and Avise, J. C. 2006. Extensive outcrossing and androdioecy in a vertebrate species that otherwise reproduces as a self-fertilizing hermaphrodite. Proceedings of the National Academy of Sciences of the United States of the America 103: 9924-9928

Maynard Smith, J. 1974. The theory of games and the evolution of animal conflicts. Journal of Theoretical Biology 47: 209-221

Maynard Smith, J. and Parker, G. A. 1976. The logic of asymmetric contests. Animal Behaviour 24: 159-175

McEwen, B. S. 2000. The neurobiology of stress: From serendipity to clinical relevance. Brain Research 886: 172-189

Minamimoto, M., Sakakura, Y., Soyano, K., Akaba, Y. and Hagiwara, A. 2006. Plasma sex steroid levels and steroidogenesis in the gonad of the self-fertilizing fish Rivulus marmoratus. Environmental Biology of Fishes 75: 159-166

Mesterton-Gibbons, M., Marden, J. H. and Dugatkin, L. A. 1996. On wars of attrition without assessment. Journal of Theoretical Biology 181: 65-83

Mommsen, T. P., Vijayan, M. M. and Moon, T. W. 1999. Cortisol in teleosts: Dynamics, mechanisms of action, and metabolic regulation. Reviews in Fish Biology and Fisheries 9: 211-268

Muller, M. N. and Wrangham, R. W. 2004. Dominance, cortisol and stress in wild chimpanzees (Pan troglodytes schweinfurthii). Behavioral Ecology and Sociobiology 55: 332-340.

Nelson, R. J. 2006. Contexts and ethology of vertebrate aggression: Implication for the evolution of hormone-behavior interactions. Biology of Aggression, Oxford University: 179-291

Oliveira, R. F., Silva, A. and Canário, A. V. M. 2009. Why do winners keep winning? Androgen mediation of winner but not loser effects in cichlid fish. Proceedings of the Royal Society B 276: 2249-2256

Olsson, M. 1994. Nuptial coloration in the sand lizard, Lacerta agilis: An intra-sexually selected cue to fighting ability. Animal Behaviour 48: 607-613

Ong, K. J., Stevens, E. D. and Wright, P. A. 2007. Gill morphology of the mangrove killifish (Kryptolebias marmoratus) is plastic and changes in response to
terrestrial air exposure. Journal of Experimental Biology 210: 1109-1115

Oyegbile, T. O. and Marler, C. A. 2005. Winning fights elevates testosterone levels in California mice and enhances future ability to win fights. Hormones and
Behavior 48: 259-267.

Oyegbile, T. O. and Marler, C. A. 2006. Weak winner effect in a less aggressive mammal: Correlations with corticosterone but not testosterone. Physiology & Behavior 89: 171-179

Pankhurst, N. W. and Van Der Kraak, G. 2000. Evidence that acute stress inhibits ovarian steroidogenesis in rainbow trout in vivo, through the action of cortisol. General and Comparative Endocrinology 117: 225-237

Parikh, V. N., Clement, T. S. and Fernald, R. D. 2006. Androgen level and male social status in the African cichlid, Astatotilapia burtoni. Behavioural Brain Research 166: 291-295

Parker, G. A. 1974. Assessment strategy and the evolution of fighting behaviour. Journal of Theoretical Biology 47: 223-243

Peters, P. J., Bronson, F. H. and Whitsett, J. M. 1972. Neonatal castration and intermale aggression in mice. Physiology and Behavior 8: 265-268

Popma, A., Vermeiren, R., Geluk, C. A. M. L., Rinne, T., Van den Brink, W., Knol, D. L., Jansen, L. M. C., Van Engeland, H. and Doreleijers, T. A. H. 2007. Cortisol moderates the relationship between testosterone and aggression in delinquent male adolescents. Biological Psychiatry 61: 405-411

Pottinger, T. G., Carrick, T. R., Hughes, S. E. and Balm, P. H. M. 1996. Testosterone, 11-ketotestosterone, and estradiol-17ß modify baseline and stress-induced interrenal and corticotropic activity in trout. General and Comparative Endocrinology 104: 284-295

Price, K. and Ydenberg, R. 1995. Begging and provisioning in broods of asynchronously-hatched yellow-headed blackbird nestlings. Behavioral Ecology and Sociobiology 37: 201-208

Rodgers, E. W., Earley, R. L. and Grober, M. S. 2006. Elevated 11-ketotestosterone during paternal behavior in the Bluebanded goby (Lythrypnus dalli). Hormones and Behavior 49: 610-614

Ross, C. N., French, J. A. and Patera, K. J. 2004. Intensity of aggressive interactions modulates testosterone in male marmosets. Physiology & Behavior 83: 437-445

Ruiz-de-la-torre, J. L. and Manteca, X. 1999. Effects of testosterone on aggressive behaviour after social mixing in male lambs. Physiology & Behavior 68: 109-113

Rutte, C., Taborsky, M. and Brinkhof, M. W. G. 2006. What sets the odds of winning and losing? Trends in Ecology & Evolution 21: 16-21

Sakakura, Y. and Noakes, D. L. G. 2000. Age, growth, and sexual development in the self-fertilizing hermaphroditic fish Rivulus marmoratus. Environmental Biology of Fishes 59: 309-317

Schuett, G. W., Harlow, H. J., Rose, J. D., Van Kirk, E. A. and Murdoch, W. J. 1996. Levels of plasma corticosterone and testosterone in male copperheads (Agkistrodon contortrix) following staged fights. Hormones and Behavior
30: 60-68

Schuett, G. W. 1997. Body size and agonistic experience affect dominance and mating success in male copperheads. Animal Behaviour 54: 213-224

Schuett, G. W. and Grober, M. S. 2000. Post-fight levels of plasma lactate and corticosterone in male copperheads, Agkistrodon contortrix (Serpentes, Viperidae): Differences between winners and losers. Physiology & Behavior 71: 335-341

Scott, A.P., Pinilos, M. and Ellis T. 2001. Why measure steroids in fish plasma when you can measure them in water? Perspective in Comparative Endocrinology: Unity and Diversity (Ed. by Goos, T. E., Rastogi, R. K., Vaudry, H. and Pieranton, R.), Monduzzi Editore, Bologna: 1291-1295

Scott, A. P. and Ellis, T. 2007. Measurement of fish steroids in water—a review. General and Comparative Endocrinology 153: 392-400

Soma, K. K. 2006. Testosterone and aggression: Berthold, birds and beyond. Journal of Neuroendocrinology 18: 543-551

Stamps, J. A. and Krishnan, V. V. 1997. Functions of fights in territory establishment. The American Naturalist 150: 393-405

Stockley, P., Gage, M. J. G., Parker, G. A. and Møller, A. P. 1997. Sperm competition in fishes: The evolution of testis size and ejaculate characteristics. The American Naturalist 149: 933-954

Summers, C. H., Larson, E. T., Summers, T. R., Renner, K. J. and Greenberg, N. 1998. Regional and temporal separation of serotonergic activity mediating social stress. Neuroscience 87: 489-496

Taillon, J. and Côté, S. D. 2006. The role of previous social encounters and body mass in determining social rank: An experiment with white-tailed deer. Animal Behaviour 72: 1103-1110

Taylor, D. S. 2000. Biology and ecology of Rivulus marmoratus: new insights and a review. Florida Scientist 63: 242-255

Taylor, D. S., Fisher, M. T. and Turner, B. J. 2001. Homozygosity and heterozygosity in three populations of Rivulus marmoratus. Environmental Biology of Fishes 61: 455-459

Taylor, D. S., Turner, B. J., Davis, W. P. and Chapman, B. B. 2008. A novel terrestrial fish habitat inside emergent logs. The American Naturalist 171: 263-266

Trainor, B. C., Bird, I. M. and Marler, C. A. 2004. Opposing hormonal mechanisms of aggression revealed through short-lived testosterone manipulations and multiple winning experiences. Hormones and Behavior 45: 115-121

Trainor, B. C. and Hofmann, H. A. 2006. Somatostatin regulates aggressive behavior in an African cichlid fish. Endocrinology 147: 5119-5125

Vargas, J. P., Rodríguez, F., López, J. C., Arias, J. L. and Salas, C. 2000. Spatial learning-induced increase in the argyrophilic nucleolar organizer region of dorsolateral telencephalic neurons in goldfish. Brain Research 865: 77-84

Villars, T. A. 1983. Hormones and aggressive behavior in teleost fishes. Hormones and Aggressive Behavior (Ed. by Svare, B. B.), New York: Plenum: 407-433

Wingfield, J. C., Hegner, R. E., Dufty, A. M. Jr. and Ball, G. F. 1990. The “Challenge Hypothesis”: Theoretical implications for patterns of testosterone secretion, mating systems, and breeding strategies. The American Naturalist 136: 829-846

Wingfield, J. C., Jacobs, J. D., Soma, K., Maney, D. L., Hunt, K., Deborah, W., Meddle, S., Ramenofsky, M. and Sullivan, K. 1999. Testosterone, aggression, and communication: Ecological bases of endocrine phenomena. The Design of Animal Communication (Ed. by Hauser, M. D. and Konishi, M.), the University of California: 255-284

Wingfield, J. C., Soma, K. K., Wikelski, M., Meddle, S. L. and Hau, M. 2001. Life cycles, behavioural traits and endocrine mechanisms. Avian Endocrinology (Ed. by Dawson, A. and Chaturvedi, C. M.), New Delhi: Narosa Publishing House: 3-17

Wingfield, J. C. 2005. A continuing saga: The role of testosterone in aggression. Hormones and Behavior 48: 253-255

Whitehouse, M. E. A. 1997. Experience influences male-male contests in the spider Argyrodes antipodiana (Theridiidae: Araneae). Animal Behaviour 53: 913-923

Woodley, S. K. and Moore, M. C. 1999. Female territorial aggression and steroid hormones in mountain spiny lizards. Animal Behaviour 57: 1083-1089

Yang, E. J. and Wilczynski, W. 2002. Relationships between hormones and aggressive behavior in green Anole lizards: An analysis using structural equation modeling. Hormones and Behavior 42: 192-205

Yang, E. J. and Wilczynski, W. 2003. Interaction effects of corticosterone and experience on aggressive behavior in the green Anole lizard. Hormones and Behavior 44: 281-292

Yang, S. Y. 2008. The decay function of experience effects in the contest of Kryptolebias marmoratus. Master’s thesis. Taipei, Taiwan: National Taiwan Normal University