On the ecology and behavior ofCebus albifrons in eastern Colombia: II. Behavior

A 503-contact-hr study of a 35 member group ofCebus albifrons was conducted in eastern Colombia in 1977 and 1978. The reactions of the group often centered on the largest adult male, which seemed dominant over all other members of the group. This “alpha” male reacted to perceived danger by putting himself between the group and the danger where he threatened and observed until the other members left the scene. Many members of the group sought the alpha's physical support while using threatening behaviors. Much tolerance towards juveniles and infants was shown by adult and subadult males which included carrying young animals out of danger. Territorial behavior was observed towards neighboring groups. Many behaviors were similar to other species ofCebus.     

New species of Podandrogyne (Cleomaceae) I. Two species from western Colombia and eastern Panama

Podandrogyne chocoensis and Podandrogyne caucana, two new species of Cleomaceae from western Colombia and eastern Panama, are described and illustrated. In view of their probable relationship to each other, but somewhat isolated position with respect to the majority of species of Podandrogyne, the new subsection Breviracemosae is proposed.     

Niche separation in Varecia variegata rubra and Eulemur fulvus albifrons: I. Interspecific patterns

Niche separation was documented in a year-long study of Varecia variegata rubra and Eulemur fulvus albifrons on the Masoala Peninsula, Madagascar. Feeding trees were measured, and diet, forest height, and forest site were recorded at 5-min time points on focal animals. For time point data, multivariate and bivariate analysis of frequencies was employed to examine how niche dimensions vary between species according to sex, season, and reproductive stage. V. v. rubra feeds in larger trees than E. f. albifrons. V. v. rubra has a diet consisting mainly of fruit, whereas E. f. lbifrons has a more varied diet. V. v. ubra ranges mainly above 15 m in tree crowns, whereas E. f. albifrons ranges mainly below 15 m in a wide array of forest sites. Both species are largely frugivorous, but they harvest fruit in different-sized trees, in different quantities, and in different forest strata. Niche partitioning varies in tandem with seasonal shifts in climate and food availability and with reproductive stages. Seasonal shifts in forest site and forest height use are largely attributed to species-specific tactics for behavioral thermoregulation and predator avoidance. The diet of E. f. albifrons is diverse whether examined by season or reproductive stage. However, females of both species diversify their diets with more low-fiber protein than males during gestation, lactation, and the hot seasons. This pattern is most pronounced for V. v. rubra females and may be directly attributed to high energetic investment in reproduction. These results suggest that niche partitioning may be driven more by the energetic requirements of reproductive females than males.     

Blood parasites in some birds from eastern plains of Colombia.

A total of 315 birds representing 75 species (23 families) from Villavicencio and San Miguel (Meta, Colombia) were examined for haematozoa. Fifty birds (15.9%) harbored blood parasites. Microfilariae were the most common haematozoans encountered, followed by species of the genera Haemoproteus, Plasmodium and Trypanosoma. This survey included 15 new host-parasite records and 8 species of birds that were examined for haematozoa for the first time. The prevalence registered in this research was similar to others recorded in the Neotropical region, but in sharp contrast with the prevalence of blood parasites in other major land masses.     

On our best behavior: optimality models in human behavioral ecology

This paper discusses problems associated with the use of optimality models in human behavioral ecology. Optimality models are used in both human and non-human animal behavioral ecology to test hypotheses about the conditions generating and maintaining behavioral strategies in populations via natural selection. The way optimality models are currently used in behavioral ecology faces significant problems, which are exacerbated by employing the so-called ‘phenotypic gambit’: that is, the bet that the psychological and inheritance mechanisms responsible for behavioral strategies will be straightforward. I argue that each of several different possible ways we might interpret how optimality models are being used for humans face similar and additional problems. I suggest some ways in which human behavioral ecologists might adjust how they employ optimality models; in particular, I urge the abandonment of the phenotypic gambit in the human case.     

The density ofAlouatta seniculus in the eastern llanos of Colombia

The density ofAlouatta seniculus groups was calculated and group components recorded in each of two areas of more than 100 ha, separated by 150 km in the llanos of eastern Colombia. Densities in each area were remarkably similar at 4 groups/km² and group structure comparable, although space utilization was somewhat different.     

东喜马拉雅地区多孔菌区系和生态习性

对东喜马拉雅地区多孔菌区系和生态习性进行了分析,发现该地区多孔菌极为丰富,共有10目19科101属372种,其中优势科为多孔菌科和锈革孔菌科,优势属为木层孔菌属和多孔菌属。种的区系地理成分可以分为8类,其中北温带类型种类最多,表明东喜马拉雅地区多孔菌具有明显的北温带区系特征。该地区的多孔菌有常见种、偶见种、稀有种和濒危种分别为156、141、54和21个;有腐生菌304种、寄生菌49种、菌根菌19种。在寄主方面,能够生长在被子植物上的有256种,裸子植物上的有137种,既能生长在被子植物,也能生长在裸子植物上的有40种,地上生长的有19种。东喜马拉雅地区的裸子植物,特别是云杉属、松属和冷杉属树木对于多孔菌的生长更重要,因为生长在这些属树木上的多孔菌分别有71、68和51种,高于该地区被子植物其他属树木上的多孔菌。     

Gorilla ecology and behavior

Many factors influence the evolution of primate grouping patterns, including phylogeny, demographic and life-history variables, and ecological factors such as access to food, predation pressure, and avoidance of infanticide. The interaction between these factors determines social organization.¹ Because western lowland and mountain gorillas differ so dramatically in their habitats and foraging strategies, they provide a valuable opportunity to assess how changes in ecology influence this balance. Mountain gorillas live in high-altitude montane forests, are herbivorous, and live in stable and cohesive groups. Western lowland gorillas live in lowland rainforest and are much more frugivorous than mountain gorillas. It is not yet clear to what extent incorporating significant quantities of fruit in the diet influences western lowland gorilla sociality because they have been studied much less than have mountain gorillas. However, what is known about their behavior hints that there may also be considerable differences in their social organization, including changes in group size and cohesion and in the frequency and type of intergroup encounters. Gorillas thus provide a unique opportunity to reevaluate proposed models of ecological influences on social organization in African apes.© 1998 Wiley-Liss, Inc.     

Ecology Institute prizes 1991 in the field of limnetic ecology

Ecology Institute prizes 1991 in the field of limnetic ecology     

The ecology and social behaviour of the Neotropical butterfly Heliconius xanthocles Bates in Colombia

The mimicry, population ecology¹, adult behaviour and life cycle of Heliconius xanthocles were studied at two sites in Colombian tropical forest. The results were compared with the known biology of other Heliconius species. H. xanthocles is probably unpalatable and is a Mullerian comimic of some other species. In the Amazon basin H. xanthocles belongs to the 'dennis ray' mimicry ring of the Heliconiini, which includes Eueides tales, H. bumeyi, H. elevatus, H. melpomene and H. erato. In the Rio Negro valley, where the latter species either do not exist or have different mimetic allegiances, the 'clennis-ray' pattern of H. xanthocles breaks down. The adults are pollen-feeders, like other Heliconius. but they also visit other food sources such as bird droppings. During a mark-recapture programme in the Rio Negro, adults were found to be almost entirely restricted to small areas near their foodplant Passiflorapraeacuta. Females were rarer than males, but this was probably due to a behavioural difference between the sexes. The males had a Fisher-Ford survival rate of 0.95 per day and a life expectancy of 19 days. Population size estimates of males were between 11 and 17 individuals. These estimates are lower than, but comparable to those for other Heliconius. Males as well as females visit the larval toodplant, and an adult male was observed hovering over a small group of larvae. The females lav batches of 12–41 eggs. The largest batch (41 eggs) was laid cooperatively by two females. The larvae are gregarious feeders on shoot-tips of Passiflora praeacuta. and all lile stages are described for the first time. Predation on the larvae by a bug is described. The pupa has a distinctive morphology unlike that of other Heliconius. The adult population ecology, mimicry and larval behaviour are discussed.     

Germination ecology of the weed Parthenium hysterophorus in eastern Ethiopia

Germination ecology of Parthenium hysterophorus, recently introduced to Ethiopia, was studied in a series of experiments. Viability of the seeds was greater than 50% after 26 months of burial in the soil indicating the potential build‐up of a substantial persistent soil seed bank. A short period of dry storage was sufficient to overcome a light requirement for germination in a minor fraction of the seeds. Likewise, seeds exhumed from burial showed an increase in germination ability in darkness over time, with a weak tendency for seasonal cyclicity in dormancy level at one of two sites. Germination occurred at the mean minimum (10°C) and maximum (25°C) temperatures of the collection sites, as well as over a wide range of fluctuating (12/2°C‐35/25°C) temperatures in light. No germination of P. hysterophorus seeds occurred at osmotic potentials < ‐0.52 MPa (at 27°C), the species being less tolerant to moisture stress than sorghum grains. Most seedlings emerged from shallowly buried (< 0.5 cm) seeds and none from more than 5 cm depth. Naturally dispersed seeds required about 60 days, at a hot lowland site, to start emergence despite the presence of adequate rainfall, and higher number of seedlings emerged in undisturbed plots than in hand hoed plots. These experiments and field observations suggest that there are no obvious climatic conditions that may limit the germination of Parthenium hysterophorus in Ethiopia, but a high moisture requirement of the seeds for germination could be the major factor limiting germination during the dry season.