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The evolutionary relationships among 13 species representing all six subgenera of the shrimp genusPenaeuswere examined using 558 bp of mitochondrial (mt) DNA from the cytochrome oxidase subunit I gene. Analyses of this sequence revealed high genetic divergence between species (d=8–24%), a finding which contrasts with previous work, which indicated that genetic diversity, based on electrophoretic analysis of allozymes, was extremely low inPenaeus.Three tree-building methods (maximum parsimony, neighbor joining, and maximum likelihood) were concordant in indicating that current subgenera assignments do not reflect evolutionary partitions within the genusPenaeus.While the molecular phylogenies cast doubt on the validity of subgenera, the observed relationships are concordant with biogeographic boundaries across the tropical range ofPenaeus.Both the western Atlantic and eastern Pacific contain monophyletic species pairs which cluster together in all analyses. The Indo-Pacific contains a putative basal taxa (P. indicus), the deepest mtDNA lineages, and the highest diversity, including representatives of all three primary lineages observed inPenaeus.These data are consistent with the suggestion by Dallet al.(1990) thatPenaeusarose in the Indo-Pacific and radiated eastward and westward to account for the current circumtropical distribution of the genus. This phylogenetic framework forPenaeuswill enhance the scientific foundations for wildlife resource management and breeding experiments (hybridization and related manipulations) designed to improve the commercial value of captive strains.

Data on the Sambia—a tribe living in Papua New Guinea—are presented to demonstrate how Sambia males develop a homosexual orientation in boyhood and adolescence, then switch to become heterosexuals in adulthood. Social learning theory is used to explain how sexual orientation in the Sambia change from homo- to heterosexual during the transition to adulthood. Whereas most learning analyses of sexual orientation are based on data from Western cultures, this manuscript extends that literature to deal with a non-Western culture. While including Pavlovian and operant conditioning, which is stressed in many learning analyses of sexual learning, the present analysis also includes detail on the social and cognitive learning principles that are important in understanding the learning of sexual orientation and behavior.

Observations onCebus capucinusin 10 forests in Chiriqui, Panama, are reported. Troop size ranged from two to five in small forests to 20 or more in large forests. A 10 week study was conducted in a coastal forest that contained a troop of 27 to 30Cebus. The troop’s daily path length was approximately 1.6 to 2.5 km and their home range was between 32 and 40 ha. TheCebususually spent 50 to 70% of their day foraging and traveling. On one occasion, aCebusattacked anIguana, wrestled with it, eventually broke off 30 to 40 cm of its tail, and ate meat from the tail. The relations betweenCebusandSaimiri oerstedii, Alouatta palliata, and man are described.

Various functional theories of play stress that social play is essential for the practice and learning of sex roles, dominance relationships, troop culture, integration of individuals into the troop structure, the control of aggression, etc. Data on squirrel monkeys (Saimiri) in natural environments indicate that social interaction and troop integration can develop in various manners in the absence of social play.

Data from primate studies suggest that social spacing in many species is controlled by conditioning effects. As do monkeys, humans divide up their social space in ways that closely reflect underlying personality factors and social patterns. Although much of social spacing is beyond conscious awareness in daily life, the study of animals and humans has begun to establish the factors that govern proxemic behavior.

Eight troops containing a total of 151 howler monkeys were studied for 513 h between December19, 1970, and February 25, 1971. The troops contained 26 mothers with their infants. Mother-infant and other adult female-infant interactions were analyzed for infants from all three age classes. The data extend the knowledge of howler behavior in three ways. First, the study broadens the comparative data on Alouatta palliata to cover a new geographic area, a coastline forest in southwestern Panama. Second, the data provide the most detailed description of infant behavioral development and mother-infant interactions available in the howler literature. And third, since the population density of 10.4 howlers per ha at the study site is one of the highest densities reported in the primate literature, the present study contributes to the analysis of how primates adapt to conditions of high population density. Comparisons are made between the adult female-infant interactions observed on Barro Colorado Island and those observed at the present study site.

Eight troops ofAlouatta villosa (= A. palliata) were studied for 10 weeks in a natural forest in southwestern Panama. This is one of the few extended studies on the species to be conducted in a location other than Barro Colorado Island. The 151 animals belonging to 8 troops and 6 additional isolates utilized 37 acres of forest. This population density was 21 times greater than on Barro Colorado in 1932 and 12 times than on Barro Colorado in 1967. The average troop size was 18.9 animals; the average home range was 12.1 acres. Home ranges overlapped extensively and on the average troops had only 6% of their home range for exclusive use. There were no signs that the howling monkeys were exhausting their food supply or were experiencing decreased fertility. Several factors that could function in population control are evaluated.

Troops ofSaimiri (squirrel monkeys) were observed in 31 locations in natural habitats in Panama, Colombia, Brazil, and Peru. Troop size varied from 10 to 35 animals in Panama and Colombia and from 120 to 300 or more in the unaltered rainforests of Amazonia. Troop size correlated with forest size in all areas.Saimiri associated withCebus (capuchin monkeys) in several areas.Saimiri troops showed different responses to man, fear and flight or neutral responses or curiosity; and these correlated with local environmental conditions. Social behavior varied significantly between the large and small troops. Social interactions were much more frequent and individual distances were much smaller in the large troops than in the small troops. Several factors that may relate to these differences in sociability are discussed in light of data from this and other studies.

Groups of squirrel monkeys (Saimiri) that are exposed to certain seasonal environmental stimuli experience a yearly reproductive cycle with discrete mating and birth seasons. Seasonal rainfall or some rainfall induced seasonal changes (such as changes in vegetation or insect fauna) appear to be responsible for timing theSaimiri reproductive cycle. Animals of both sexes show significant physiological and behavioral changes during the yearly cycle. Whether the environmental timing factors affect both the males and the females equally, or affect only one sex directly and the other sex indirectly through social communication is not clear. Three mechanisms by which the reproductive activity of both males and females could be synchronized are presented, and data from a laboratory study and a field study relevant to each mechanism are presented. Several social interaction patterns frequently observed in the field study suggest that (1) male sexual activity may excite female sexual activity through male penile display and/or other stereotyped interactions and/or (2) female sexual activity may excite male sexual activity through pheromone and/or other communication channels.

Hormone injection is a common spawning induction technique in aquaculture but is of limited use in small species with low fecundity. An alternative to injection for such species is topical gill application. We conducted an experiment with female rainbow sharks Epalzeorhynchos erythrurus(Cyprinidae) in one control group and three treatment groups: (1) topical gill application of dimethyl sulfoxide (DMSO), (2) topical gill application of DMSO and Ovaprim, and (3) an Ovaprim intramuscular (IM) injection. Ovaprim contains a salmonid gonadotropin-releasing hormone analog and a dopamine antagonist. Fish were anesthetized, treated, and placed into recovery tanks. Fish were manually checked for ovulation by exerting abdominal pressure at 8, 10, and 11 h posttreatment and were observed for mortality during a 24-h period. Ovulation varied significantly: we found no ovulation of females in the control or DMSO groups, 78% ovulation in the DMSO plus Ovaprim group, and 100% ovulation in the Ovaprim IM injection group. Only two mortalities occurred in 24 h, both in the injected group. Use of DMSO as a solvent for topical gill application of hormones shows some promise as a spawning induction technique for tropical ornamental fishes.

Squirrel monkeys (Saimiri) have been studied in a variety of laboratory and natural environments. The frequency and form of exploration and social play vary considerably among different environments. For example, in some environments, young monkeys have been observed to play for 3 hr per day; but in one natural environment, not a single bout of social play was seen during a 10-week intensive study. Numerous intermediate levels of play activity have been observed. Whereas many theories of play make it appear that play is essential for the development of sexual behavior, integrated roles in troop structure, control of aggressive responses, social cohesion, etc., the data on squirrel monkeys indicate that social organization and many normal social behaviors can develop without social play. However, the opportunity to play socially provides learning experiences that increase the variety of each animal's behavioral repertoire and the subtly of social cues to which it can respond. An adaptive modicum of competence can appear without social play, but the opportunity to play socially develops the competence of animals beyond that modicum.