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Noë, R., & Hammerstein, P. (1995). Biological markets. Trends. Ecol. Evol, 10(8), 336–339.
Abstract: In biological markets, two classes of traders exchange commodities to their mutual benefit. Characteristics of markets are: competition within trader classes by contest or outbidding; preference for partners offering the highest value; and conflicts over the exchange value of commodities. Biological markets are currently studied under at least three different headings: sexual selection, intraspecific cooperation and interspecific mutualism. The time is ripe for the development of game theoretic models that describe the common core of biological markets and integrate existing knowledge from the separate fields.
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Connor, R. C. (1995). Altruism among non-relatives: alternatives to the 'Prisoner's Dilemma'. Trends Ecol Evol, 10(2), 84–86.
Abstract: Triver's model of reciprocal altruism, and its descendants based on the Prisoner's Dilemma model, have dominated thinking about cooperation and altruism between non-relatives. However, there are three alternative models of altruism directed to non-relatives. These models, which are not based on the Prisoner's Dilemma, may explain a variety of phenomena, from allogrooming among impala to helping by non-relatives in cooperatively breeding birds and mammals.
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Krebs, J. R., Clayton, N. S., Hampton, R. R., & Shettleworth, S. J. (1995). Effects of photoperiod on food-storing and the hippocampus in birds. Neuroreport, 6(12), 1701–1704.
Abstract: Birds that store food have a relatively large hippocampus compared to non-storing species. The hippocampus shows seasonal differences in neurogenesis and volume in black-capped chikadees (Parus atricapillus) taken from the wild at different times of year. We compared hippocampal volumes in black-capped chickadees captured at the same time but differing in food-storing behaviour because of manipulations of photoperiod in the laboratory. Differences in food-storing behaviour were not accompanied by differences in the volume of the hippocampus. Hippocampal volumes also did not differ between two groups of a non-food-storing control species, house sparrows (Passer domesticus), exposed to the same conditions as the chickadees.
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Mesterton-Gibbons, M., & Dugatkin, L. A. (1995). Toward a theory of dominance hierarchies: effects of assessment, group size, and variation in fighting ability. Behav. Ecol., 6(4), 416–423.
Abstract: We introduce assessment to the analysis of dominance hierarchies by exploring the effect of an evolutionarily stable fighting rule when there is variation in resource holding potential (RHP) and RHP is not a perfectly reliable predictor of the outcome of a fight. With assessment, the probability of a linear hierarchy decreases with group size but can remain appreciable for groups of up to seven or eight individuals, whereas it decreases virtually to zero if there is no assessment. The probability of a hierarchy that correlates perfectly with RHP is low unless group size is small.
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Keverne, E. B. (1995). Olfactory learning. Curr. Opin. Neurobiol., 5(4), 482–488.
Abstract: Unravelling the mechanisms of learning and memory can, and should, be tackled at many levels. Discovery of the huge family of odourant receptor genes provided olfaction with `molecular' respectability similar to that afforded to the visual system. Consequently, molecular studies have dominated the olfactory literature this past year, even to the point of providing a molecular basis of olfactory perception. Needless to say, the molecular approach favours a `hard-wired' system; however, other results suggest that flexibility in the olfactory system provides for certain adaptations that are crucial to the biological needs of mammals.
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Saltz, D., & Rubenstein D.I. (1995). Population Dynamics of a Reintroduced Asiatic Wild Ass (Equus Hemionus) Herd. Ecol Appl, 5(2), 327–335.
Abstract: Reintroduction is the release of animals into an area where they were extirpated or have significantly declined. Little is known about the factors that determine the success of failure of ungulate reintroduction. We studied the dynamics of a reintroduced Asiatic wild ass (Equus hemionus) population for 10 yr (1983-1993) following the first successful release into the wild. A total of 14 adult females and 14 adult males were released into a nature reserve in the Negev Desert of southern Israel. Over this 10-yr span the female population has grown to only 16 adults. Reproductive success of reintroduced females was low in the first 5 yr following release (0.0-0.8 foals@?female^-^1@?yr^-^1), but increased to 0.5-1.0 foals@?female^-^1@?yr^-^1 in the last 5 yr. Reproductive success of wild-born females @>3 yr old was higher than that of reintroduced females of similar ages, and ranged from 0.5-1.0 foals@?female@?^-^1yr^-^1. Our study and data from the E. hemionus studbook suggest that young nonprimiparous females produced primarily males, while primiparous and old females produced primarily females. We attribute the low reproductive success following reintroduction to the stress caused by capture, transport, and release procedures; we consider the age-dependent progeny sex ratio within the framework of Trivers and Willard's (1973) maternal allocation hypothesis. We conclude that the slow growth of the female population was due to: (a) low reproductive success of females in the early years following reintroduction, and (b) a male-skewed progeny sex ratio among prime-aged reintroduced females. A simple stochastic Leslie matrix model suggests that high survival and improved reproductive success of reintroduced females at later stages of the study, and the reproductive success of wild-born females, make the population relatively unsusceptible to extinction from random demographic processes. In-depth knowledge of the dynamics of reintroduced populations is vital for the correct assessment of their viability. We offer suggestions for increasing the efficacy of future wild ass reintroductions.
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Loveland, K. A. (1995). Self-recognition in the bottlenose dolphin: ecological considerations. Conscious Cogn, 4(2), 254–257.
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Hart, D., & Whitlow, J. W. J. (1995). The experience of self in the bottlenose dolphin. Conscious Cogn, 4(2), 244–247.
Abstract: Marten and Psarakos have presented some evidence which suggests that objective self-awareness and possibly representations of self may characterize the dolphins' experience of self. Their research demonstrates the possibility of similarities in the sense of self between primate species and dolphins, although whether dolphins have subjective self-awareness, personal memories, and theories of self--all important facets of the sense of self in humans--was not examined. Clearly, even this limited evidence was difficult to achieve; the difficulties in adapting methods and coding behavior are quite apparent in their report. Future progress, however, may depend upon clarification of what are the necessary components for a sense of self and an explication of how these might be reflected in dolphin behavior. We are mindful of the authors' point (pp. 219 and 220) that the dolphin lives more in an acoustic than a visual environment. Thus, while tasks relying upon vision may reveal the presence or absence of the sense of self in primates, it might well be the case that in dolphins self-related experiences might be better revealed in auditory tasks. But then, what is the nature of human self-awareness in terms of audition? While both conceptual and methodological hurdles remain, Marten and Psarakos have demonstrated that important questions can be asked about the minds and phenomenal worlds of nonanthropoid species.
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Anderson, J. R. (1995). Self-recognition in dolphins: credible cetaceans; compromised criteria, controls, and conclusions. Conscious Cogn, 4(2), 239–243.
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Marten, K., & Psarakos, S. (1995). Using self-view television to distinguish between self-examination and social behavior in the bottlenose dolphin (Tursiops truncatus). Conscious Cogn, 4(2), 205–224.
Abstract: In mirror mark tests dolphins twist, posture, and engage in open-mouth and head movements, often repetitive. Because postures and an open mouth are also dolphin social behaviors, we used self-view television as a manipulatable mirror to distinguish between self-examination and social behavior. Two dolphins were exposed to alternating real-time self-view (“mirror mode”) and playback of the same to determine if they distinguished between them. The adult male engaged in elaborate open-mouth behaviors in mirror mode, but usually just watched when played back the same material. Mirror mode behavior was also compared to interacting with real dolphins (controls). Mark tests were conducted, as well as switches from front to side self-views to see if the dolphins turned. They presented marked areas to the self-view television and turned. The results suggest self-examination over social behavior.
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