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Assortative mating in the dimorphic lesser snow goose could be explained if birds choose mates according to the color of their parents. Young birds were tested to determine if they would show color preferences at an early age. Blue and white phase lesser snow geese, as well as white phase geese dyed pink, were reared in families with either a blue, white, or pink foster parent. All birds were then combined in a large flock in an attempt to simulate natural conditions as closely as possible. Birds tested in a choice situation were found to show a significant preference for birds of the same color as their foster parents. The fact that the young were raised in families and later in a flock suggested that color preferences were a natural and not a laboratory phenomenon.Two lines of evidence suggest that where the color of the foster parent is altered, the preference for the color of the original foster parent is lost. This suggests that prolonged association of gosling and parent is important if parental color is to have an influence on mate selection.

1983. Light intensity as a factor in the choice of an oviposition site by Drosophila pseudoobscura and Drosophila persirnilis. Can. J. Genet. Cytol. 25: 370-377. Light preferences for ovipositing of the sibling species Dro.sophila p.seudoobscura and D . persirnilis were measured in a multichoice chamber. Behavioral differentiation was found among sympatric populations of D . pseudoobscura and D. persirnilis and between allopatric populations of D . p.seudoobscura. Differences among isofemale lines within populations indicated genetic variability for the behavior. Both D. pseudooh.scura populations were less fecund in a uniform light environment than in the multichoice environment while D . persirnilis showed no difference in fecundity in the two environments. The patterns for general photoresponse and ovipositional light response were shown to be different for each population. Thus, the motivation to oviposit may affect photopreference differentially in each population. WOGAMAN, D. J., et M. B. SEIGER. 1983. Light intensity as a factor in the choice of an oviposition site by Drosophila p.seudoob.scura and Drosophila persirnilis. Can. J. Genet. Cytol. 25: 370-377. La preference de lumiere pour l'oviposition des especes cryptique Drosophila pseudoobscura et D . persirnilis fut mesurke dans une chambre de test d'alternatives multiples. On trouva des diffkrences de comportement entre les populations sympatriques de D . pLseudoobscura et de D. persirnilis et entre les populations allopatriques de D . pseudoobsc.ura. Les differences de cornportement entre les lignes isofernelles dans les populations indiquaient une variabilite genetique. Les deux populations de D . pseudoobsc.ura etaient moins fecondes dans un milieu de lumiere uniforme que dans un milieu de choix multiples, tandis que les D. per.sirni1i.s ne montrerent aucune difference de fecondite dans les deux milieux. Les modeles pour la photoreponse generale et pour la reponse a la lumiere pendant l'oviposition ktaient demontrks comme etant differents pour chaque population. Ainsi, la motivation d'ovipondre peut affecter la photoprkference diffCrentielle dans chaque population. IntroductionThe choice of an oviposition site is important for understanding the adaptiveness of Drosophiltr species. Carson (197 1 ), in a review of field studies, pointed out that Drosophila are generally more selective in choosing an oviposition site than a feeding site. He suggested that choice of a site for oviposition has been more important as an adaptation to the environment than choice of a feeding site. The few laboratory studies of ovipositing preference have generally utilized chemical cues and substrate surface preference. Both D . rnelanogaster and D . pseudoobsc.ura have been shown to be gregarious during egg laying which is probably due to a response to a chemical cue (Del Solar and Palomino 1966;Del Solar 1968), possibly a pheromone from males feeding at the site (Mainardi 1968). McKenzie and Parsons (1972) found that D. melunogaster showed a slight preference for ovipos...

Five isofemale strains from each of four sympatric species, Drosophila immigrans, D. repleta, D. melanogaster, and D. affinis, were lightly anesthetized with ether, CO2, Flynap, or cold temperature. The photoresponse of each treatment group was measured in an open field and a Y-tube apparatus. Relative light values were compared with those of the unanesthetized control groups of each species, as well as among the different treatments themselves and among species. Significant differences between species were apparent for all treatments in the Y-tube and for all treatments except ether and CO2 in the open field. Response to anesthesia may differ between species due, in part, to their differing genotypes. Comparing treatment groups within species in the Y-tube design, all species except D. melanogaster showed significant differences between treatments. In the open field, only D. affinis was significantly affected. Particularly in the Y-tube, anesthetized flies generally differed significantly from the controls, indicating that the use of anesthesia during a behavioral study could cause deviations in behavior from that of normal unanesthetized flies.

Selection was carried out on a population of Drosophila pseudoobscura to obtain lines preferring high-light intensity or low-light intensity during oviposition. This species is generally characterized as preferring low-light intensities. It was possible to select for increased preference for high-light intensity, but not for low-light intensity during oviposition. However, additive genetic variability exists in preferences for both high- and low-light intensities. The original population was probably operating at a photonegative extreme for oviposition, yet maintained enough genetic variability to permit selection toward a photopositive preference.