DEEP ETHOLOGY: DEVELOPMENT
			BEHAVIORAL PLASTICITY

Behavioral patterns change at various levels of organization in specific ways. They are the endpoint (OUTPUT) of a process that begins with INPUT (such as sensory information) and INTEGRATION (of the sensory information with other variables about the organism including the effects of previous experiences and competition with alternative possible responses).

REFLEXES (and strings of reflexes termed fixed action patterns (FAPs) or motor programs) are relatively inflexible in expression, but can be evoked by varying stimuli. [In practice, FAP refers to an "instinctive" or "automatized" behavior pattern -- they are functionally similar but instincts are particularly rapidly learned -- so fast in fact they may appear innate, or completely genetically determined] The path from stimulus to response can vary depending on multiple variables such as enabling or inhibiting physiological circumstances. Such circumstances include the availability of substrate to synthesize neurotransmitters, the rate of synthesis, the rate of their release, or recent activities that may have exhausted or replenished a cell's competence to act (such as short-term adaptation or habituation).
Many changes in behavior are secondary to developmental change: for example -- the same stimulus and integrative activity can have an apparently different outcome if body size and shape are different; developmental changes in physiology (such as puberty or pregnancy or menopause) can affect the availability of neuromodulating hormones. There are also "windows of opportunity" for change that "open and close" depending on developmental and environmental circumstances -- some are programmed in development and others depend on specific environmental conditions -- these are "sensitive periods" leading to phenomena such as imprinting or rapid learning.

In honey bees, "Behavioral differences arise as part of a system of age-related, socially regulated division of labor common to species of social insects. Bees perform several different tasks in the hive during the first 2 to 3 weeks of adult life, including brood care ("nursing"), and then shift to foraging for nectar and pollen outside the hive for the remainder of their 5- to 7-week life. Like other forms of behavioral plasticity, such as social dominance and sexual behavior in vertebrates, the transition to foraging in the honey bee involves long-term, environmentally modulated changes in behavior that are associated with changes in brain structure, brain neurochemistry, and expression in the brain of at least a few genes. However, the extent of gene expression changes associated with bee behavioral plasticity is not known."

Individual bees vary in several ways in how they perform their jobs, due to both intrinsic factors and changes in the environment that affect colony needs. For example, foragers fly to food sources located at distances from several meters to several kilometers from the hive, under variable weather conditions, and may specialize on collecting pollen or nectar, or on one or more floral species. Both nurses and foragers vary in performance tempo, with some individuals working harder than others. The timing of the transition from hive work to foraging is itself variable and may be accelerated, delayed, or reversed depending on the needs of the colony.

“Several forms of animal behavior are known to be influenced by the activity of specific genes. Microarray studies have been used to relate changes in behavior with changes in gene expression in the brain. These studies identified average trends for groups of animals, but did not examine gene expression in individuals. But identifying average differences between groups is not the same as identifying differences that can reliably predict behavior in individuals (8). This is especially the case for behavior performed outside of a laboratory setting where the experiences of each individual can vary widely. To predict behavior from gene expression profiles in a natural context would demonstrate a more robust relation between genes and behavior than is commonly thought to exist." (from Whitfield et al. (2003) Gene Expression Profiles in the Brain Predict Behavior in Individual Honey Bees. SCIENCE 302(5643): 296-299).

Changes in behavior attributed to parasite or infection (selectively irritating the nervous system? activating specific psychoactive genes?) "Solitary parasitoid insects usually lay only one egg per host and reject already parasitized hosts, as only one offspring can successfully develop (1). Despite the constraints, superparasitism is commonly observed. A body of theoretical works has explained that the decision of a parasitoid to lay extra eggs can be advantageous and selected for when host’s are rare (2). However, superparasitism in a solitary Drosophila parasitoid was not determined by parasitoid nuclear genes but caused by an infectious extra-chromosomal factor. This microparasite takes advantage of the wasp’s superparasitism behavior for its own transmission. This leads to reconsider the evolutionary interpretation of this behavior. A comparison of seven laboratory strains of Leptopilina boulardi showed clear between-population variation in superparasitism behavior. . . This trait was also highly variable within strains, even in the Sienna strain that was initiated from a single female. To investigate the origin of such variability, 20 inbred lines were established from the Sienna strain. Stable lines were obtained: some of them never caused superparasitism (NS lines), while others laid up to 15 eggs in the same host [S lines . . .]. Crosses between S and NS inbred lines (3) revealed strict maternal transmission of the phenotypes: both F1 and back-crosses behaved similarly to their maternal ancestors. The same result was obtained when crossing two natural populations (Antibes and Madeira) also showing contrasting superparasitism behavior (table S1). Variability in superparasitism behavior appeared to be induced by an extra-chromosomal factor that is vertically transmitted through maternal lineage. To investigate whether this extra-chromosomal factor was infectious, we first parasitized Drosophila larvae by NS females (from Madeira) and subsequently superparasitized the larvae by S females (from Antibes). At emergence of the adult parasitoids, females were individually tested for their behavior and for their genotype using a molecular marker that allows to distinguish the two strains . . . . They were compared to control females emerging from hosts parasitized only by Madeira females, or by Antibes females (within-strain competition), respectively. All controls behaved as expected: Madeira females never allowed superparasitism, while Antibes did. Among the winners of the between-strain competition, all Antibes females favored superparasitism as expected, while 71% (46/65) of Madeira females also favored superparasitism in spite of their genotype. This result showed that superparasitism behavior was horizontally transmitted and is probably regulated by an infectious extra-chromosomal factor present in the S line. Superparasitism behavior of newly infected lines was stable over generations, suggesting that the infectious factor settled durably. The apparent infectiousness of superparasitism behavior strongly suggests the involvement of a replicating particle in S females. Preliminary electron microscopy suggests a virus is involved, since particles were observed in S females (8/9)and not in NS females (0/6). Because superparasitism in L. boulardi is not determined by parasitoid’s genes but by a microparasite, the adaptive significance of this behavior for the parasitoid needs to be reconsidered. Modification of the wasp’s behavior makes it more likely that hosts will be infested with both uninfected and infected females, favoring horizontal transmission of the particles. However, consequence of this behavioral modification for the fitness of the microparasite is not so evident since it suffers a trade-off between horizontal and vertical transmission. Several parameters of the association (physiological cost of infection, efficiency of vertical transmission, parasitoid/Drosophila ratio) need to be estimated before we can decide whether this phenomenon should be interpreted as a mere pathological effect or as a true adaptive manipulation. (from "Infectious Behavior in a Parasitoid" by Julien Varaldi et al.(2003) at www.sciencexpress.org on 16 October 2003.)

Learning as a biological phenomenon "...observations of natural learning tend to encourage the view that learning consists, not of a unitary general capacity, but of a collection of specialized abilities which have evolved independently in particular species in order to do specific jobs." When asked "what is learning for?" T.J. Roper. believes it that involves information pertaining to the individual's experience in the world rather than experiences so reliably encountered by the species that these needs would have come to be encoded in the genome. (1983 in Genes, Development, and Learning, Halliday and Slater, eds. pp 178-212.) feels it is to solve practical problems. Galef (1976 in Adv Stud. Behav, 6:77-100) One of the practical problems is particular to social species: the need to make predictions about conspecifics (A. Jolly, 1966, in: Science 153:501-506; N.K. Humphrey, The social function of intellect, in Growing Points in Ethology, Bateson & Hinde, eds, pp 303-317.) [jump to notes on learning]

Neuroplasticity The structure and function of the nervous system is generally presumed to be the materialist basis for all behavioral actions. examples of neuroplasticity Cognitive Ecology Internal and environmental information converge to shape behavior, but the capacity to change as a result of experience and the paths change may take are highly subject to environmental selection pressures, guiding evolution of traits that can best be characterized as cognitive. “Cognitive Ecology lays the foundations for a field of study that integrates theory and data from evolutionary ecology and cognitive science to investigate how animal interactions with natural habitats shape cognitive systems.” Essay on evolutionary ecology of learning

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Oct 2008