Elevada abundância de drosofilídeos e baixa riqueza de espécies, uma realidade da composição em ambiente cultivado de Pernambuco

Os drosofilídeos são organismos que se adaptam aos mais variados ambientes, naturais preservados ou antropizados. Os impactos causados em áreas naturais interferem diretamente na composição das diferentes espécies que colonizam este ambiente. Por apresentar sensibilidade às variações ambientais, essas pequenas moscas vêm sendo utilizadas como bioindicadoras naturais de alterações ambientais, enquanto outras possuem grande poder de dispersão e colonização em diferentes ecossistemas. Alterações ambientais podem interferir na abundância das espécies presentes no ambiente natural, ocasionando a extinção local de alguma destas espécies. Entre os biomas brasileiros, a Floresta Atlântica é o mais destruído pelas ações antrópicas, sendo, por isso, considerada uma das prioridades mundiais para a conservação da biodiversidade. Com a finalidade de melhor compreender os efeitos desse processo e caracterizar a composição de Drosophilidae (Insecta, Diptera) em um ambiente devastado de Floresta Atlântica, considerada área de cultivo no Município de Nazaré da Mata, Pernambuco, esses insetos foram coletados em dois períodos sazonais distintos (chuvoso e seco). Foram amostrados um total de 5524 indivíduos, sendo 3405 no período chuvoso e 2119 no período seco, representados por quatro (Drosophila, Rhinoleuconphenga, Sacaptodrosofila e Zaprionus) e 16 espécies de drosofílideos, dos quais o gênero Drosophila apresentou maior representatividade, com 13 espécies reconhecidas. Contabilizando ambas as coletas, houve uma grande predominância de três espécies exóticas: Drosophila malerkotliana, D. simulans e Zaprionus indianus, que representam 78% do total de indivíduos. A análise da riqueza (Taxa S) foi similar entre os períodos amostrados, entretanto, a maior abundância de indivíduos foi registrada no período das chuvas. Os resultados de análise de diversidade de Simpson (1-D) e Shannon (H) apontam que não houve diferença significativa para os períodos sazonais quanto à fauna de drosofílídeos.

Photomap of the polythenic chromosomes of Drosophila malerkotliana and in situ mapping of the Hsp83 locus

A photomap of the polythenic chromosomes of D. malerkotliana was constructed to facilitate the identification of the chromosomal arms and their sections, in order to allow the identification of the breaking points of inversions and the location of the bands marked by in situ hybridization. The photomap of the polythenic chromosomes of D. malerkotliana was constructed with the six chromosome arms corresponding to pairs I (chromosome X), II and III, which are submetacentric and pair IV and Y chromosome were not included because they were not visualized in the material examined, probably due to their small size. The in-situ hybridization was performed on polythenic chromosome slides of 3 individuals. Fourteen marks were observed in Sect. 98 of the chromosomal arm IIIR, representing 70% of the markings. Other marks were found in Sect. 91 (2 marks, 10%), 87 (2 marks, 10%) and 85 (1 mark, 5%) of the same arm and in Sect. 25 (1 mark, 5%) of the IIL chromosomal arm. In this work, a photomap was made and mapped by in situ hybridization a physiologically important gene, the first being mapped in D. malerkotliana, representing the beginning of a complete study of the chromosomal evolution of the species, which will also include the induction of poufs by stress or hormones such as ecdysone.

Photomap of the polythenic chromosomes of Drosophila malerkotliana and in situ mapping of the Hsp83 locus

A photomap of the polythenic chromosomes of D. malerkotliana was constructed to facilitate the identification of the chromosomal arms and their sections, in order to allow the identification of the breaking points of inversions and the location of the bands marked by in situ hybridization. The photomap included the six chromosome arms corresponding to pairs I (chromosome X), II and III, excluding pair IV and Y chromosome, because they were not visualized in the material examined, probably due to their small size. Through the in situ hybridization technique with the use of a biotined probe of a fragment of the D. melanogaster gene, the Hsp83 locus of D. malerkotliana was mapped. The probe hybridized with a frequency of 70% in section 98 of the IIIR chromosome. This is the first mapped gene in the species, and indicates that possibly the IIIR arm of D. malerkotliana corresponds to the IIIL arm of D. melanogaster, where the Hsp83 gene was located.

Occurrence of Drosophilids in the Pernambuco’s coastal region (years 2000-2001) and the Frequency of chromosomal inversions found in Drosophila malerkotliana

Drosophilids were collected in the campus of UFPE (Recife), Rio Doce (Olinda), Vila Velha (Itamaracá), Parque de dois Irmãos (Recife) and Charles Darwin Ecological Refuge (Igarassu), in the years 2000 and 2001, seeking to establish the frequency of occurrence of the various species of the genus Drosophila. In these collections, D. malerkotliana occurred in an average frequency of 64%, followed by D. melanogaster, with an average frequency of 23%. The frequency of D. malerkotliana was higher than that of D. melanogaster in localities with high and medium degree of urbanization. Despite the great distance from the distribution center of the species (Africa), D. malerkotliana presented high polymorphism of chromosomal inversions. In the locality of Rio Doce, inversions In(IIL)24B-39A and In(IIL)21-25, occurred with frequencies of 18.5% and 100%, respectively, while inversion In(IIIR)84-88B occurred with a frequency of 100%. In the population of campus UFPE (Recife), also with high urbanization, two inversions were found, In(IIIR)93C-94A and In(IIIL)64A-72A with frequencies of 37.1 and 60%, respectively. In the population of The Parque de Dois Irmãos (Recife), with medium urbanization, four inversions were visualized: In(IIIL)70C-73B (66%); In(IIIR)93C-94A (52%); In(IIL)24B-39A (33%); and In(IIR)50B-51A (33%). In the population of the Charles Darwin Ecological Refuge (Igarassu), of low urbanization, only the inversion In(IIIR)100A-98B(?) was found. −88(?), with 100% frequency. These data suggest that the polymorphism of inversions is higher in localities with greater urbanization, possibly due to the longer colonization time, which allowed the accumulation of genetic variations.

Drosophila malerkotliana y Zaprionus indianus (Diptera, Drosophilidae) invaden poblaciones ecuatorianas de Drosophila

La introducción voluntaria o accidental de especies exóticas produce impactos severos en el equilibrio de los ecosistemas. En este estudio se reporta la presencia en territorio ecuatoriano de dos drosofilídeos asiáticos: Drosophila malerkotliana Parshad y Paika (1964) y Zaprionus indianus Gupta (1970). D. malerkotliana, comúnmente invasiva, está presente en todas las regiones biogeográficas del planeta y tiene una plasticidad sorprendente. En febrero del 2006, esta especie fue detectada en el Páramo de Guamanà(Páramo de la Virgen), en la provincia de Pichincha, Ecuador, entre los 3900-4000 msn indianus también está presente en varias regiones biogeográficas del planeta y en los últimos aftos está invadiendo el Neotrópico. Esta especie fue capturada por primera vez en enero del 2004 en la provincia de Pichincha en las faldas del Ilaló cerca de Quito, a 2500 msnm, y luego en Tumbaco, Guayllabamba y Otongachi. Z. indianus también ha sido colectada en las provincias de Esmeraldas (Playa Ancha), Imbabura (Ibarra), Manabà(Montecristi, Jipijapa) y Ore llana (Estación Científica Yasuní). D. malerkotliana y Z. indianus están incrementando su área de distribución en el país: D. malerkotliana tratando de conquistar ecotopos insospechados y Z. indianus compitiendo con las drosófilas ecuatorianas. Los efectos que puedan causar estas especies invasoras en los ecosistemas son desconocidos.

Chromosomal phylogeny and geographical divergence in the Drosophila bipectinata complex

We have prepared reference polytene photographic maps as a standard sequence for the Drosophila bipectinata complex using structurally homozygous flies derived from a stock of Drosophila parabipectinata from Brunei, Borneo, in 1971. We found 87 inversions in the D. bipectinata complex and described their breakpoints on the reference maps. Only 2 arrangements were shared interspecifically: 2R-AB was shared with 3 species, D. parabipectinata, D. bipectinata, and Drosophila malerkotliana, and 3L-A was found in 2 species, D. parabipectinata and D. malerkotliana. The 2 subspecies of D. malerkotliana and the 2 subspecies of Drosophila pseudoananassae shared half of the total gene arrangements detected in each species. The number of different inversions found between species in the complex ranges from 7 (between D. parabipectinata and D. malerkotliana) to at least 24 (between D. bipectinata and D. pseudoananassae). On the basis of the characteristic differences of their gene arrangements, we propose a reliable chromosomal phylogeny of the D. bipectinata complex.Key words: chromosomal phylogeny, Drosophila bipectinata, inversion polymorphisms.

No character displacement for reproductive isolation between Drosophila bipectinata and Drosophila malerkotliana

To test whether character displacement for reproductive isolation between Drosophila bipectinata and Drosophila malerkotliana exists, the degree of sexual isolation was measured between their sympatric and allopatric populations. Although the isolation indices vary in different crosses, the average isolation index for sympatric populations is very close to that for allopatric populations. This shows no difference in the degree of sexual isolation between sympatric and allopatric populations of D. bipectinata and D. malerkotliana. Thus there is no evidence for the existence of character displacement for sexual isolation between these two closely related sympatric species.Key words: Drosophila bipectinata, Drosophila malerkotliana, sexual isolation, sympatric and allopatric populations.