Tripanossomatídeos (protozoa: Kinetoplastida) Em Três Espécies De Cascudos Do Rio Mogi-guaçu, Pirassununga, São Paulo, Brasil

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Genetic diversity in natural populations of Jacaranda decurrens Cham. determined using RAPD and AFLP markers

Jacaranda decurrens (Bignoniaceae) is an endemic species of the Cerrado with validated antitumoral activity. The genetic diversity of six populations of J. decurrens located in the State of São Paulo was determined in this study by using molecular markers for randomly amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP). Following optimization of the amplification reaction, 10 selected primers generated 78 reproducible RAPD fragments that were mostly (69.2%) polymorphic. Two hundred and five reproducible AFLP fragments were generated by using four selected primer combinations; 46.3% of these fragments were polymorphic, indicating a considerable level of genetic diversity. Analysis of molecular variance (AMOVA) using these two groups of markers indicated that variability was strongly structured amongst populations. The unweighted pair group method with arithmatic mean (UPGMA) and Pearson's correlation coefficient (RAPD -0.16, p = 0.2082; AFLP 0.37, p = 0.1006) between genetic matrices and geographic distances suggested that the population structure followed an island model in which a single population of infinite size gave rise to the current populations of J. decurrens, independently of their spatial position. The results of this study indicate that RAPD and AFLP markers were similarly efficient in measuring the genetic variability amongst natural populations of J. decurrens. These data may be useful for developing strategies for the preservation of this medicinal species in the Cerrado

Fine-scale genetic structure overrides macro-scale structure in a marine snail: nonrandom recruitment, demographic events or selection?

The planktotrophic littorinid species Littoraria flava occupies a continuous habitat on rocky shores close to brackish and freshwater sources. Previous studies of this species have shown a moderate genetic structure over a broad geographical scale, with high deviations from Hardy-Weinberg expectations in many allozymic loci. Local-scale subdivision in marine species with a long dispersal phase is unexpected, but occasionally found. Using a horizontal transect at three locations, we examined whether microscale and short-term subdivision also occurred in L. flava populations and, if so, whether this could explain the Hardy-Weinberg deviations. Littoraria flava showed even more structuring on a microgeographical scale (4-300 m) than on a large-scale (> 200 km). The Ewens-Watterson neutrality test showed that 18% of the tests deviated significantly from the neutrality model. A homogeneity test for each locus across samples within transects showed homogeneous and high F-IS values in many loci. These results and the apparent genetic patchiness within transects suggest that asynchronous spawning associated with recurrent colonizations in L. flava can explain the local differentiation without a recognizable pattern. In addition, there could be a balance between these factors and diversifying selection acting on different loci at different times and localities. (c) 2007 The Linnean Society of London.911233

The influence of size on the radula of Littoraria angulifera (Gastropoda : Littorinidae)

We evaluated the radula shape of Littoraria angulifera from mangroves and rocky shores on the Brazilian coast. We compared snails sampled in a mangrove and on a rocky shore located about 100 m apart, and also from locations hundreds of km apart. Smaller individuals sampled on rocky shores have elongated cusps, whereas larger individuals have subequal cusps, similar to those observed in mangrove specimens. Distinct factors in each environment might exert different effects on the radula shape of L. angulifera. The greater morphological diversity observed on the rocky shores might be due to the heterogeneity of algae composition and partitioning of resources, a hypothesis that can be tested in further studies.4911

Genetic population structure and hybridization in two sibling species, Tomoplagia reticulata and Tomoplagia pallens (Diptera: Tephritidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Tomoplagia reticulata and T. pallens are sibling species that are specialists on Eremanthus glomerulatus. Besides adult terminalia, they show slight morphological differences and distinct geographic distributions. Once, however, they were found sympatrically. Using data from allozyme and mtDNA, we examined patterns of intra- and interspecific genetic structure, and investigated the possible occurrence of gene flow between them. Both species showed low diversity and high genetic structure, which can be linked to their high degree of specialization. Larval development occurs within flower heads, tissues that are available only during a short period of the year. Afterward, as they do not hibernate, they probably suffer a great reduction in population size, which leads to low genetic diversity. As monophagous insects, their population structure may correspond to the fragmented distribution of E. glomerulatus, which could isolate fly populations and increase inbreeding within them. One population exhibited a mixed genetic composition, compatible with one hybridization season when species were sympatric. This hybridization seems to be a rare event, due to T. pallens unusual range expansion.7412981311Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CNPq [141539/2004-6]FAPESP [98/05085-2, 04/097420

Worms without borders: genetic diversity patterns in four Brazilian Ototyphlonemertes species (Nemertea, Hoplonemertea)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Understanding the evolutionary processes from recent demographic history is especially difficult for interstitial organisms due to their poorly known natural history. In this study, the genetic variation and population history of the four Ototyphlonemertes (Diesing in Sitz ber Math Nat Kl Akad Wiss Wien 46:413-416, 1863) species were evaluated from samples collected along the Brazilian coast (between 27A degrees 31'S and 13A degrees 00'W) in 2006. The mitochondrial region cytochrome c oxidase subunit 3 (COX3) is analyzed to assess the genetic variation of these dioecious species. Although these species have a sympatric distribution along the coast, our data suggest that their levels of differentiation and their demographic histories differ sharply. There is strong evidence of gene flow among demes in O. erneba and O. evelinae, and their level of structuring is much lower than for the other two species. Indeed, the COX3 fragment reveals cryptic lineages in O. lactea and O. parmula. The results seem to contradict the high genetic structuring and low intrapopulational variability expected with the ecological constriction and habitat discontinuity faced by these organisms, meaning that there might be gene flow among populations or their dispersal capability has been underestimated.158921092124Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Smithsonian InstitutionFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAEP [519/292]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [05/56347]FAEP [519/292

Patterns of genetic variability in Brazilian Littorinids (Mollusca): a macrogeographic approach

Macrogeographic studies are important for understanding gene flow patterns, and comparative data for related species with distinct bionomical traits may help to clarify the importance of such traits in natural populations. The aims of this study were to quantify the genetic variability and the populational structuring of three Brazilian littorinid species (Nodilittorina lineolata, Littoraria flava and L. angulifera) and to discuss the relationship between them, as well as each species' mode of development and spatial distribution. We also investigated the species diversity in the ziczac complex. Isozyme analyses were done on 20 samples of N. lineolata, nine of L. flava and 10 of L. angulifera, collected along 4000 km of the Brazilian coast. Sixteen polymorphic loci were analysed in N. lineolata, 15 in L. angulifera and 17 in L. flava. All species showed high genetic variability. At sites where more than one species was present, there was a correlation among the values of gene diversity.The degree of interpopulational differentiation (N. lineolata, F-ST = 0.028; L. flava, F-ST = 0.054; L. angulifera, F-ST = 0.185) was coherent with the mode of larval development of each species. No linkage disequilibrium was found in N. lineolata. These findings, together with morphological evidence, corroborated the existence of only one species of the ziczac complex along the Brazilian coast.41424925

Low genetic differentiation between isolated populations of the colonial ascidian Symplegma rubra Monniot, C. 1972

Pelagic larvae are highly important for maintaining the gene flow among populations of sessile marine invertebrates. Colonial ascidians consist, exclusively, of brooding species, with lecithotrophic larvae that have a limited dispersal. As a result, there is a marked differentiation among populations. In this work, we used allozyme electrophoresis to access the genetic variation in four populations of Symplegma rubra, a colonial ascidian frequently found in the intertidal zone of Southeastern Brazilian coast. High variability was found at three of the four sites sampled, the exception being Praia Grande in the State of Rio de Janeiro. At this site, there was a great preponderance of clones, which possibly reflected the enclosed nature of the location and its low water circulation that reduce the dispersal capabilities of these animals. S. rubra did not conform to expectations for random mating (Hardy-Weinberg equilibrium): there was a deficit of heterozygotes that was more related to the small population size than to inbreeding processes, since F (is) analysis per locus revealed a deficiency of heterozygotes at only one locus-MDH*. The greatest variation in allele frequency was found for GPI-2*. Analyses of genetic variability revealed moderate differentiation among the populations (F (ST)=0.051), which was unexpected for a species with a low dispersal capability. Rafting, a frequently underestimated means of dispersal, may be the main mode of gene flow in this species over large areas, since colonies of S. rubra are frequently seen growing on drift material and there is no evidence that the larva survive for a long time in the plankton.148480781

Homogeneity test of Hardy-Weinberg deviations in Brazilian littorinids: Evidence for selection?

Echinolittorina lineolata, Littoraria flava and L. angulifera (Gastropoda: Littorinidae) have a wide distribution along the Brazilian coast. The aim of this study was to evaluate the occurrence of Hardy-Weinberg disequilibrium in these species and to verify if there is a pattern in deviations. Isozyme analyses were done on 20 populations of E. lineolata, nine of L. flava and 10 of L. angulifera, collected along 4,000 km of the Brazilian coast. Sixteen polymorphic loci were analysed in E. lineolata, 15 in L. angulifera and 17 in L. flava. Most populations showed heterozygote deficiency in several loci. A homogeneity test among loci showed heterogeneous F-IS values in most populations. This result ruled out inbreeding and the Wahlund effect as the main causes of departure in these populations. In all littorinid species, at least one PGM locus had homogeneous F-IS values. This finding may suggest that this enzyme could have an important role in the fitness of these periwinkles.71216717

High genetic variability in Neotropical myophilous orchids

The patterns of genetic variability of seven Bulbophyllum Thouars species were investigated using 14 enzymatic loci, and compared with those of other Neotropical myophilous orchid species. The genetic variability estimated was very high (H-e = 0.39-0.61, P = 86-100%, A = 2.6-3.8), despite the small population sizes, which may be explained by the vegetative reproduction. Of the three species with multiple populations, only B. epiphytum showed moderate values of genetic structuring. Environmental characteristics and seed dispersal mechanisms are important in understanding the differences in the population structure observed. Almost all pairs of species showed low genetic similarity, indicating a long period of divergence. Our results suggest that B. adiamantinum and B. insectiferum, species currently classified in different sections of the genus, are more closely related than previously thought. (c) 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 153, 33-40.1531334