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This work is a brief review of a series of studies of the phenotypic organization and ecological significance of individual differences in fish behavior. The following species were studied: guppy Poecilia retuculata, lion-headed cichlid Steatocranus cassuarius, and the convict cichlid Archocentrus nigrofasciatum. We developed methods for the analysis of individual differences in fish behavior and studied their structure, development, and ecological and evolutionary significance. Individual differences are important primarily because they are the basic material for evolution (Darwin, 1859). The basic ecological and adaptive mechanisms maintaining individual differences in behavior within a single population are currently known. They primarily include the frequencydependent selection (Wilson @et al.,@ 1994; Wilson, 1998). Nonetheless, most studies of individual differences in the behavior of fish and other animals until now involved only the adaptive value of isolated behavioral elements and tactics. Motivational mechanisms of individual differences remain almost unclear. Also absent is a unitary comparative approach, including the study of the phenotypic structure of individuality, its motivational determinants, as well as ecological and evolutionary significance. INDIVIDUALITY: HOW TO MEASURE IT? In the study of any differences between species, populations and individuals, the basic unit of analysis is character (Yablokov and Larina, 1985; Mina, 1986; Yablokov, 1987, 1988). The concept of character includes any trait, which can vary between the species, populations or individuals (Michener and Sokal, 1957; Langlet, 1971; Mina, 1986). In the study of morphological and physiological variation, characters are not very difficult to define and measure. However, in behavioral studies this is often not an easy task. The behavior of each individual depends on both its motivational state in a particular time and the immediate environmental stimuli. Even in the controlled experimental conditions it is almost impossible to create completely identical environment for all individuals. They receive and respond to somewhat different stimuli. It is also impossible to exclude the random variation of behavior, the more so that natural selection can maintain even completely random behavioral tactics (Cooper and Kaplan, 1982; Labas and Krylov, 1983; Kaplan and Cooper, 1984). All this at first glance completely contradicts the possibility to find stable individual characteristics of the individual. This problem, the extraction of stable characteristics of individuality from constantly changing in response to the environment overt behavior, is so important not only in the study of animal behavior. It first appeared in the beginning of the 20 century in psychology when it became necessary to measure such "immeasurable" phenomena as intellect and personality. This is why psychologists developed a system of methods for the extraction of stable characteristics of personality and factors of intelligence, which could be used also in the study of animal behavior (Harrington, 1988). Two different aspects of stability are usually distinguished in psychology and psychometrics (Eysenck, 1970; Eysenck and Eysenck, 1985): there is a fundamental distinction between "stability" and "consistency." When one speaks of stability of certain behavior, this usually means that this behavior does not change. Consistency of a particular behavioral measure means, that it is characterized by high predictability or correlation during repeated measurement (temporal stability or continuity) or across various situations even if the overall average level of this measure changes (Nunnally, 1967; Ozer, 1986). For example, an individual exhibiting higher level of aggressiveness than other individuals in one situation could also be more aggressive than others in another situation even if the behavior overall differs in these situations (figure). Thus, the behavior may be situation-specific whereas individual differences, consistent. The significant consistency of temperament and the fact, that they could appear in various situations make temperament very important in the ecological sense. For example, our studies revealed assortative mating with respect to the level of boldness in male and female. This evidences, that temperament plays an important role in the mate choice in fishes. Temperament determines characteristics of parental care, especially such important element as food provisioning. At the same time, the pattern of parental brood provisioning significantly affects the subsequent life of the offspring. The importance of temperament for fish ecology is also supported by the data, indicating that fish with different temperament differ in habitat preference, the structure of the ration, characteristics of schooling behavior etc. (Wilson @et al.,@ 1993; Budaev, 1997b). Thus, temperament could provide an important element for the comparative and integrative approach to the study of behavior, unifying analysis of general phenotypic structure of individuality, possible motivational and physiological mechanisms, and their ecological and evolutionary significance.()，英语论文，英语论文题目 |
