ABSTRACT
O gênero Rhinoleucophenga Hendel compreende 18 espécies nominais e possui distribuição Neotropical e Neártica. Uma nova espécie foi encontrada em coleta realizada em Florianópolis, SC, e é descrita como Rhinoleucophenga joaquina sp. nov. Os espécimes encontrados emergiram de flores de Dyckia encholirioides (Bromeliaceae) coletadas em região de restinga sobre dunas. Este é o primeiro registro da utilização de flores como sítio de oviposição para Rhinoleucophenga.
The genus Rhinoleucophenga Hendel comprises 18 nominal species and has a Neotropical and Nearctic distribution. A new species was found in a collection in Florianópolis, SC, Brazil, and is described as Rhinoleucophenga joaquina sp. nov. The specimens found were reared from flowers of Dyckia encholirioides (Bromeliaceae), collected in a region of restinga on the dunes. The use of flowers as breeding site for Rhinoleucophenga has never been reported before.
Subject(s)
Animals , Drosophilidae/anatomy & histology , Drosophilidae/classification , BrazilABSTRACT
The phenotypic plasticity of wing size and wing shape of Zaprionus indianus was investigated in relation to growth temperature (17 degrees C to 31 degrees C) in two natural populations living under different climates, equatorial and subtropical. The two populations were clearly distinguished not only by their wing size (the populations from the colder climate being bigger in size), but also by the shape of the response curves to growth temperature i.e., their reaction norms. In this respect, the temperature at which the size of the wing was maximum was about 3 degrees C higher in the equatorial population. Such a difference in size plasticity is already found in two other nonclosely related species, might be a general evolutionary pattern in drosophilids. Wing shape was investigated by calculating an ellipse included into the wing blade, then by considering the ratio of the two axes, and also by analysing the angular position of 10 wing-vein landmarks. For an overall shape index (ratio of the two axes of the ellipse), a regular and almost linear increase was observed with increasing temperature i.e., a more round shape at high temperatures. Wing shape was also analysed by considering the variations of the various angles according to temperature. A diversity of response curves was observed, revealing either a monotonous increase or decrease with increasing temperature, and sometimes a bell shape curve. An interesting conclusion is that, in most cases, a significant difference was observed between the two populations, and the difference was more pronounced at low temperatures. These angular variations are difficult to interpret in an evolutionary context. More comparative studies should be undertaken before reaching some general conclusions.
Subject(s)
Adaptation, Physiological , Animals , Climate , Drosophilidae/anatomy & histology , Female , Male , Organ Size , Phenotype , Temperature , /anatomy & histologyABSTRACT
Mesosternal (MS) bristles in Drosophila are a pair of machrochaetae found at the sternal end of the sternopleural (STP) microchaetae, and are thought to be invariable. In a closely related drosophilid genus, Zaprionus, their number is four and, in contrast to Drosophila, they show interspecific and intraspecific variability. The genetic basis of MS bristle number variability was studied in Z. indianus, the only cosmopolitan species of the genus. The trait responded rapidly to selection and two lines were obtained, one lacking any bristles (0-0) and the other bearing the normal phenotype (2-2). Other symmetrical phenotypes, (1-1) and (3-3), could also be selected for, but with lesser success. By contrast, STP bristle number did not vary significantly between the two lines (0-0) and (2-2), revealing its genetic independence from MS bristle number. Reciprocal crosses between these two lines showed that MS bristle number is mainly influenced by a major gene on the X chromosome (i.e. F(1) males always resembled their mothers) with codominant expression (i.e. heterozygous F(1) females harboured an average phenotype of 2 bristles). However, trait penetrance was incomplete and backcrosses revealed that this variability was partly due to genetic modifiers, most likely autosomal. The canalization of MS bristle number was investigated under different temperatures, and the increased appearance of abnormal phenotypes mainly occurred at extreme temperatures. There was a bias, however, towards bristle loss, as shown by a liability (developmental map) analysis. Finally, when ancestral and introduced populations were compared, the latter were far less stable, suggesting that genetic bottlenecks may perturb the MS bristle number canalization system. MS bristle number, thus, appears to be an excellent model for investigating developmental canalization at both the quantitative and the molecular level.