O objetivo deste trabalho foi testar a presença de mimetismo em Asclepias curassavica L., Epidendrum fulgens Brong. e Lantana camara L. O trabalho foi realizado no Parque Estadual de Itapeva/RS, no sul do Brasil, entre 2004 e 2006. O período de floração de cada uma das três espécies foi acompanhado; foram realizadas observações focais de borboletas visitantes florais a partir de um ponto fixo e observações através de caminhadas aleatórias. Também estimou-se a freqüência de remoção de polinários na orquídea, bem como o seu modo de reprodução. Todas estas variáveis foram importantes para testar a hipótese do mimetismo. Embora tenham ocorrido algumas coincidências temporais nos períodos de floração entre duas das plantas do sistema, não houve associação estatisticamente significativa no período de floração das três plantas. Foram registradas 29 espécies de borboletas, dentre as quais Agraulis vanillae maculosa, Dryas iulia alcionea, Urbanus simplicius, Tegosa claudina e Heliconius erato phyllis foram as mais freqüentes nas visitas às três plantas. A correlação de Pearson mostrou que há associação entre o número de visitas realizadas a L. camara e E. fulgens (r = 0,4603; n = 19; P = 0,0473). A remoção de polinários em E. fulgens foi baixa, medida pela percentagem de remoção (amplitude: 0 - 10%). A análise do modo de reprodução mostrou a dependência da orquídea em relação a polinizadores, uma vez que nenhum fruto foi produzido a partir da autopolinização espontânea. Em contraste, a percentagem de frutos formados resultantes de geitonogamia e xenogamia foi em média 86%. Os resultados aqui relatados não são conclusivos quanto à existência de um sistema mimético entre as três plantas.

The goal of this paper was to test the presence of mimicry in Asclepias curassavica L., Epidendrum fulgens Brong., and Lantana camara L. The study was carried out at the Parque Estadual de Itapeva, RS, southern Brazil, from 2004 to 2006. Flowering period of each of the three species was followed up; focal observations of butterflies visiting flowers, from fixed point and during random walks were carried out. We also estimated the frequency of pollinaria removal in the orchid, as well as its mode of reproduction. All these variables were important for testing the mimicry hypothesis. Despite some temporal coincidences in the flowering period of two plants in the system, there was no statistical association among the three plants as to flowering period. Twenty-nine species of butterflies, as potential pollinators, were recorded, particularly Agraulis vanillae maculosa, Dryas iulia alcionea, Urbanus simplicius, Tegosa claudina, and Heliconius erato phyllis, which were the more frequent visitors of the three plants. There was association between the number of visits to L. camara and E. fulgens, based on Pearson correlation (r = 0.4603; n = 19; P = 0.0473). Pollinaria removal of E. fulgens was low, as measured by the percentage of removal (range: 0 - 10%). The analysis of the mode of reproduction of this orchid showed its pollinator-dependence, since no fruits were formed by spontaneous self-pollination. In contrast, the percentage of fruit set that resulted from geitonogamy and xenogamy was, in average, 86%. The results here shown are not conclusive as to the occurrence of a mimicry system among the three plants.

In this paper, two methods for assessing the degree of melanization of pupal exuviae from the butterfly Heliconius erato phyllis , Fabricius 1775 (Lepidoptera, Nymphalidae, Heliconiini) are compared. In the first method, which was qualitative, the exuviae were classified by scoring the degree of melanization, whereas in the second method, which was quantitative, the exuviae were classified by optical density followed by analysis with appropriate software. The heritability (h 2 ) of the degree of melanization was estimated by regression and analysis of variance. The estimates of h 2 were similar with both methods, indicating that the qualitative method could be particularly suitable for field work. The low estimates obtained for heritability may have resulted from the small sample size ( n = 7-18 broods, including the parents) or from the allocation-priority hypothesis in which pupal color would be a lower priority trait compared to morphological traits and adequate larval development.

The so-called Evolutionary Synthesis, the present paradigm for evolutionary explanations, was established during the 1920s, 1930s and 1940s. One of the leading scientists contributing to this was Theodosius Dobzhansky, a Russian born geneticist who emigrated to the United States of America in 1927 to study with Thomas Hunt Morgan. He was also responsible for the development of Drosophila genetics in Brazil, which was the main organism employed in experimental studies of evolution. Dobzhansky had several opportunities to visit Brazil starting in 1943, to do field and laboratory work as well as teaching. All these activities were fundamental in the spreading of new concepts, methodology, and objectives of the Synthesis to a new audience. This paper discusses the results of the interaction between Dobzhansky and a group of young Brazilian researchers, particularly from the University of São Paulo.

Beetles of the species Chauliognathus fallax Germar 1824 are polymorphic for elytron colouration with six morphs distinguished on the basis of black pigmentation on a yellow background. We investigated samples of C. fallax taken in eight consecutive weeks aiming to determine the frequency of the morphs which were grouped, for statistical analysis, into three classes according to elytra pigmentation as well as the possible occurrence of assortative mating. Our results showed a variation in the frequency of the classes throughout the season, both in males and females, with the maximum frequency of each class at the fourth and fifth week. The three classes (A, B, C) showed the same pattern of variation, and class B was always the more frequent. To test randomness of matings two approaches were taken: in the first, we compared the frequency of each class in copulating and non-copulating insects. In the second, the frequency of each class in the whole sample was taken as the probability of occurrence of the respective class; then, using the criterion of the probability of independent events we calculated the expected proportion of copulating insects for each pair of events. Both methods gave non-significant differences, suggesting that the matings were random.

This is the first study of isoenzyme variability in the leaf-cutting ants (Myrmicinae, Attini) Acromyrmex heyeri (Forel, 1899) and A. striatus (Roger, 1863) which are common throughout the southern Brazilian state of Rio Grande do Sul. We studied the alloenzyme variability of malate dehydrogenase (MDH), alpha-glycerophosphate dehydrogenase (alpha-GPDH) and amylase (AMY) in 97 colonies of A. heyeri and 103 colonies of A. striatus. Five loci were found for these enzyme systems, one locus (Amy-1) being monomorphic in both species and four loci (Mdh-1, alpha-Gpdh-1, Amy-2, and Amy-4) being polymorphic. For each species there were exclusive alleles for the Mdh-1 and Amy-2 loci and differences were also found in the allele frequencies for the other polymorphic loci. Ontogenetically different gene activity was detected for the MDH and alpha-GPDH systems, with between-caste differences, probably related to flight activity, also being found for alpha-GPDH.

Em alta durante quase todo o século XIX, o prestígio dos naturalistas caiu nas últimas décadas do mesmo século, na medida em que o enfoque dos estudos biológicos transitava do histórico para o funcional. A redescoberta dos trabalhos de Mendel, em 1900, e a emergência da genética aceleraram este processo, onde a atividade do experimentalista substituía a anterior. Ao mesmo tempo, o darwinismo também declinava e os primeiros anos do século XX caracterizam o chamado "eclipse do darwinismo". Theodosius Dobzhansky, russo radicado nos Estados Unidos a partir de 1927, é o pesquisador que irá reunir as duas tradições, a naturalista e a experimentalista. No desempenho de suas atividades, ele realiza um verdadeiro salto qualitativo nos estudos de evolução em populações naturais, que pela primeira vez podem ser efetuados através do método experimental, auxiliados por um rigoroso planejamento teórico. Este artigo narra algumas etapas desta história.

The high prestige naturalists had during most of the 19th century began to decrease in the last decades of that century, as the focus in biological studies switched from historical to functional. The rediscovering of Mendel's works in 1900 and the emerging of genetics made the process move faster and caused experimentalist activities to take over. Simultaneously, Darwinism was also losing ground and the first years of the 20th century were characterized by the so-called 'eclipse of Darwinism'. Theodosius Dobzhansky, a Russian researcher who moved to the United States in 1927, joined the two different traditional approaches, the naturalistic and the experimental ones. Through his activities, he accomplishes a quality leap for the study of evolution in natural populations, which can for the first time be carried out through experimental methods guided by thorough theoretical planning. This article narrates some of the steps of this story.

The relative population sizes of a species complex of Chauliognathus are reported, as well as their spatial distribution associated with different patches of food plants. Field work was done at Fazenda Santa Isabel, municipality of Guaíba, State of Rio Grande do Sul, Brazil. The results suggest that two mechanisms account for the reduction in food competition among the species involved: one is asynchrony in the appearance of the species in the area, and the other is aggregation in different patches of food plants. Since the species here reported show a similar colour pattern (yellow-black) the possibility of the occurrence of serial mimicry in this complex of species is dicussed.

This study presents data on the color polymorphism in Chauliognathus flavipes Fabricius 1781 (Coleoptera, Cantharidae), analysing the variations in the emergence pattern of phenotypic classes for elytra color and mating system. The frequency of the phenotypic classes varies significantly throughout the season (males:X² = 59,705; females: X² = 61,017; 10 gl; p<0.001) being similar in males and females. The frequency of classes does not differ significantly among the insects that were copulating and those that were not copulating at the time of collection, i.e., the matings are random for elytra color patterns. The variations observed in frequency of phenotypic classes are not influenced by factors associated with sex. Furthermore, the elytra color patterns probably do not influence the individuals' ability to copulate.