Behavior In Natural Populations Research Articles

The genetic architecture of odor-guided behavior in Drosophila melanogaster.

The avoidance response to repellent odorants in Drosophila melanogaster, a response essential for survival, provides an advantageous model for studies on the genetic architecture of behavior. Transposon tagging in a highly inbred strain of flies in combination with a rapid and simple statistical behavioral assay enables the identification of not only large phenotypic effects, but also small aberrations from wild-type avoidance behavior. The recent completion of the sequence of the Drosophila genome facilitates the molecular characterization of transposon-tagged genes and correlation between gene expression and behavior in smell-impaired (smi) mutant lines. Quantitative genetic analyses of a collection of smi lines in a coisogenic background revealed an extensive network of epistatic interactions among genes that shape the olfactory avoidance response. The identification and functional characterization of proteins encoded by smi genes that form part of the olfactory subgenome and correlation of polymorphisms in these genes with variation in odor-guided behavior in natural populations will advance our understanding of the genetic architecture of chemosensory behavior.

Measuring Similarity among Hispid Cotton Rats (Sigmodon hispidus) of Known Relatedness with DNA Fingerprinting

Determining mating strategies and social behavior of natural populations of mammals is equivocal when individuals can not be observed directly. DNA fingerprinting holds promise to elucidate relationships among individuals indirectly; however, few empirical data assess accuracy of DNA fingerprints in portraying relatedness in natural populations of mammals. Using the hispid cotton rat ( Sigmodon hispidas ) as a model, we determined accuracy of DNA fingerprinting for separating wild-caught individuals into categories according to their relatedness and ascertained repeatability of the pattern of DNA fingerprints. We used individuals from known breedings to compute similarity (S) in DNA fingerprints from pair-wise matchings. Because relatedness of these individuals was known, we obtained the actual distribution of band-sharing scores and computed the known mean S for each relatedness category. We detected significant differences in S between primary, secondary, and unrelated categories but could not distinguish statistically among related groups within these categories. High within-gel repeatability in the DNA banding pattern indicated a robust technique, but variation in scoring among readers confirmed that a single individual should score gels. Our results demonstrated that DNA fingerprints can be used to determine relatedness categories and uncover behavioral-social interactions for species that can not be observed directly. Routine demographic information (e.g., body mass, spatial proximity) collected during field studies and used in conjunction with DNA fingerprinting can provide a finer level of distinction among related groups.

Disrupted patterns of behavior in natural populations as an index of ecotoxicity.

This paper examines behavioral changes in natural populations of wildlife associated with pollution. Although some changes such as lack of nest attentiveness and decreased nest defense have been noted, the results have not been consistent and have been difficult to relate to specific pollutants. Experimental studies involving lead, mercury, and organochlorine and organophosphate insecticides are described. Although changes in behavior have been observed, they are generally more difficult to quantify and are less reproducible than biochemical changes. To date, there is no clear evidence in wildlife that behavioral changes caused by pollutants are a serious threat to populations.

Disrupted Patterns of Behavior in Natural Populations as an Index of Ecotoxicity

Disrupted Patterns of Behavior in Natural Populations as an Index of Ecotoxicity

The influence of the ability to disperse on generation length and population size in the flour beetle, Tribolium castaneum

Abstract. In Tribolium castaneum Herbst, in which dispersal is genetically determined, it is possible to select for strains that are characterized by high and low dispersal, High dispersal (HD) beetles are better adapted than low dispersal (LD) beetles for colonization, as can be seen from differences that exist between the two groups with regard to several life‐history parameters. Comparisons were made between the dynamics of seventy‐two HD and seventy‐two LD populations. Generation length in HD populations was significantly shorter than in LD populations. After 91/2 weeks, in open treatments (from which dispersal away from the set was allowed), HD populations had more beetles than LD populations, whereas in closed treatments (from which dispersal away from the set was not allowed) the opposite was true. These findings may explain the maintenance of the genetic variability of dispersal behaviour in natural populations of T.castmeurn.

Problems in Detecting Chaotic Behavior in Natural Populations by Fitting Simple Discrete Models

In order to predict the long—term qualitative dynamics of natural populations with discrete generations, ecologists have used short—term field data to estimate the parameters of simple difference—equation models whose behaviors are then examined. Three problems complicate the model—fitting approach: (1) the parameter estimates, and hence the predicted dynamics, may be sensitive to the estimation procedure used; (2) different models may fit the data equivalently well and yet make different predictions about population behavior; and (3) even when the best—fit parameters are used, a simple model may fail to capture the observed dynamics of the field population. I illustrate these problems using data from published insect life—table studies. I then discuss the limitations these problems impose upon the prediction of the qualitative behavior of natural populations by means of simple best—fit models. I conclude that, given these limitations, inferences about the presence or absence of chaos in natural insect populations that rely on simple best—fit models and premature.

Genetic correlations between morphology and antipredator behaviour in natural populations of the garter snake Thamnophis ordinoides.

The genetic coupling of morphology and behaviour means that the evolution of the two types of traits will not be independent: changes in behaviour will result in changes in morphology and vice versa. This might explain nonadaptive differences in morphology through indirect selection on correlated characters of other categories. Genetic correlations between morphology and behaviour are also the basis for some models of sympatric speciation and of the stability of polymorphisms. Morphology and behaviour are often correlated in nature and a genetic basis for such couplings has been demonstrated. I present here evidence that colour pattern and antipredator behaviour are genetically coupled in natural populations of the garter snake Thamnophis ordinoides. Similar phenotypic correlations between pattern and behaviour exist among species of North American snakes, indicating that selection for particular combinations of traits may help to maintain genetic covariances and colour polymorphism in Thamnophis ordinoides.

Genetic differences in mating success and female choice in seaweed flies (Coelopa frigida).

An association is described in seaweed flies, Coelopa frigida, between the genotype at the alcohol dehydrogenase (Adh) locus and mating success in pairwise mating trials. Significantly higher mating success was observed in females that carried the Adh-C allele, but no association was observed between Adh genotype and male mating success. There was heterogeneity in the success of different combinations of males and females, but only when the female lacked the C allele. Analyses of video recordings indicated that C-bearing females spent longer mounted by males and that they less frequently rejected males. Evidence is presented for mate discrimination by females not carrying a C allele. The significance of there being genetic differences in both mating success and in female discrimination are discussed in the context of previous results on mating behaviour in natural populations.

Intermediate perennial-annual populations ofOryza perennis found in Thailand and their evolutionary significance

To reexamine the mode of variations in adaptive mechanisms in the Asian form ofOryza perennis, the breeding behavior of natural populations was observed at eight sites selected in Thailand. One population consisted of seedlings only (annual), and five consisted of ratooned plants only (perennial), while two others were mixtures of both. The annual population had a larger number of buried seeds at the habitat than had the others. In the habitat of the annual population, annual species were predominant, while perennial populations tended to coexist with perennial species. The annual population was in a temporary swamp, while perennial populations were found at sites more deeply inundated in the rainy season and retaining moisture in the dry season. This indicated the role of water stress in conditioning the reproductive strategy.

Effect of light on egg-laying rate and mating speed in phototactic strains of Drosophila

IN Drosophila, phototactic behaviour can be quantitatively described using Hirsch–Hadler classification mazes1. Flies entering the maze make a series of 15 consecutive light–dark choices and receive phototactic scores ranging from 1.0 (highly photonegative) to 16.0 (highly photopositive). A photoneutral population has an expected mean photoscore of 8.5. The phototaxis maze has provided a useful tool for the characterisation of phototactic behaviour in natural populations of Drosophila and for the creation of photopositive and photonegative strains of flies by artificial selection. Natural populations of D. melanogaster and D. pseudoobscura are photoneutral in general, but respond rapidly to selection for positive or negative phototactic behaviour2,4,7,8. Genetic analysis of phototaxis in Drosophila suggests that this behaviour is a polygenic trait with low heritability3,4,6. Suspension of artificial selection results in rapid reversion to photoneutrality which illustrates the principle of genetic homeostasis and suggests that changes in fitness accompany selection for photopositive and photonegative behaviour8.

Aggressiveness, Dominance and Social Organization in the Steller Jay

Aggressiveness and submissiveness are of primary importance in the motivation of behavior and as formative forces in avian social organization. In another paper (Brown, MS) their behavioral expression in the Steller Jay (Cyanocitta stelleri) is examined. In this paper their manifestations in the organization of a society of the Steller Jay are considered. The evolutionary consequences of aggressiveness in birds are mediated through the ecological and physiological effects of aggressive and submissive behavior in natural populations. Despite this, the studies of aggressiveness as expressed in dominance hierarchies and similar types of social relationships in captive birds far outnumber the few studies of wild birds. Since the forms of social organization taken by a number of individuals of an avian species in captivity so often differ from those in the wild, studies in the wild state are basic to the understanding of social organization. The present study contributes to the relatively meager information on dominance hierarchies in wild populations of birds. The social structure of the Steller Jay and other species, such as tits, in which dominance hierarchies in nature have been demonstrated, is excellently suited for observation of the causes and consequences of changes in aggressiveness in wild birds. Because of the regular presence of many individuals at particular loci and the possibility of determining their social rank, a sensitive index (rank) is available for the detection of slight changes in aggressiveness in a relatively large number of individuals and for the correlation of these with features of the environment and histories of individuals.

Growth, Dispersal and Age at Sexual Maturity of the Mexican Toad (Bufo valliceps Wiegmann)

THE dynamics of natural populations are extremely important to the survival of species and to their differentiation in time and space. Hereditary changes may provide the basis for adaptation, survival and differentiation, but these changes are evolutionarily significant only in a population that is meeting the problems of existence in its natural environment. Remarkably little is known, however, about the behavior in natural populations of most kinds of vertebrates. The present report deals principally with two phases of population dynamics (age of reaching sexual maturity and survival to sexual maturity) in a population of the Mexican toad (Bufo valliceps Wiegmann). The study was begun on July 21, 1951, when it was discovered that many young toads hatched in June and July had failed to disperse from the dirt tank from which they had metamorphosed or had moved to regularly watered areas some 100 to 235 feet distant from the tank. In the period of July 21 to October 22, 1951, a group of 357 young toads in the size range of 10 to 55 millimeters was marked by toe clipping. Observations on this population have been continued to October, 1952.

Population Dynamics of Rodents and Other Small Mammals

Publisher Summary Studies of social behavior and dynamics in natural populations are important, because the behavior of the individual in nature is a basic factor in gene exchange between parts of a species population. This chapter is concerned principally with such population phenomena as: (1) localization of the individual, (2) dispersal, (3) pattern of reproductive behavior, (4) life span in nature, and (5) pattern of distribution. All have a bearing on the gene exchange and geographic differentiation within natural populations. The behavior in natural populations of rodents and other small mammals, as revealed by live-trapping and nest-box studies, theoretically has important effects on the gene exchange in these populations. Attachment of an individual to a limited area of familiar terrain or home range tends to restrict gene dispersal. Estimates of home-range size for 39 species of rodents and for 9 other species of small mammals, although difficult to compare because of the differences in technique, do show the widespread occurrence of the home-range habit. The size of the home range is affected by such attributes as sex, age, mobility, body size, and food habits, and by such ecologic factors as vegetative cover, size of area, and season of the year. Dispersal of the young away from the place of birth at the approach of sexual maturity is the most important means of dispersing genes through the population.