Mendelian inheritance, linkage and genotypic disequilibrium in microsatellite loci isolated from Hymenaea courbaril (Leguminosae).

The Neotropical tree Hymenaea courbaril, locally known as Jatobá, is a valuable source of lumber and also produces comestible and medicinal fruit. We characterized Mendelian inheritance, linkage and genotypic disequilibrium at nine microsatellite loci isolated from H. courbaril, in order to determine if they would provide accurate estimates of population genetic parameters of this important Amazon species. The study was made on 250 open-pollinated offspring originated from 14 seed trees. Only one of nine loci presented significant deviation from the expected Mendelian segregation (1:1). Genotypic disequilibrium between pairwise loci was investigated based on samples from 55 adult and 56 juvenile trees. No genetic linkage between any paired loci was observed. After Bonferroni's corrections for multiple tests, we found no evidence of genotypic disequilibrium between pairs of loci. We conclude that this set of loci can be used for genetic diversity/ structure, mating system, gene flow, and parentage analyses in H. courbaril populations.

To self, or not to self... a review of outcrossing and pollen-mediated gene flow in neotropical trees.

Despite the typically low population densities and animal-mediated pollination of tropical forest trees, outcrossing and long-distance pollen dispersal are the norm. We reviewed the genetic literature on mating systems and pollen dispersal for neotropical trees to identify the ecological and phylogenetic correlates. The 36 studies surveyed found >90% outcrossed mating for 45 hermaphroditic or monoecious species. Self-fertilization rates varied inversely with population density and showed phylogenetic and geographic trends. The few direct measures of pollen flow (N=11 studies) suggest that pollen dispersal is widespread among low-density tropical trees, ranging from a mean of 200 m to over 19 km for species pollinated by small insects or bats. Future research needs to examine (1) the effect of inbreeding depression on observed outcrossing rates, (2) pollen dispersal in a wide range of pollination syndromes and ecological classes, (3) and the range of variation of mating system expression at different hierarchical levels, including individual, seasonal, population, ecological, landscape and range wide.

Monitoring genetic diversity in tropical trees with multilocus dominant markers.

Since no universal codominant markers are currently available, dominant genetic markers, such as amplified fragment length polymorphism (AFLP), are valuable tools for assessing genetic diversity in tropical trees. However, the measurement of genetic diversity (H) with dominant markers depends on the frequency of null homozygotes (Q) and the fixation index (F) of populations. While Q can be estimated for AFLP loci, F is less accessible. Through a modelling approach, we show that the monolocus estimation of genetic diversity is strongly dependent on the value of F, but that the multilocus diversity estimate is surprisingly robust to variations in F. The robustness of the estimate is due to a mechanistic effect of compensation between negative and positive biases of H by different AFLP loci exhibiting contrasting frequency profiles of Q. The robustness was tested across contrasting theoretical frequency profiles of Q and verified for 10 neotropical species. Practical recommendations for the implementation of this analytical method are given for genetic surveys in tropical trees, where such markers are widely applied.

Spinturnicid mites (Gamasida: Spinturnicidae) associated with bats in central Brazil.

The results of a survey of spinturnicid mites (Gamasida: Spinturnicidae) infesting bats near Brasília, D.F., Brazil, are presented. One hundred twenty-five bats were collected, representing three families and 15 species. Seven species of spinturnicid mites (genus Periglischrus) were collected from nine species of bats (family Phyllostomidae). Each of the following six species of Periglischrus was associated with a single species of bat: Periglischrus acutisternus Machado-Allison and P. torrealbai Machado-Allison on Phyllostomus discolor Wagner; P. paravargasi Herrin and Tipton on Anoura caudifer (E. Geoffroy); P. caligus Kolenati on Glossophaga soricina (Pallas); P. ojasti Machado-Allison on Sturnira lilium (E. Geoffroy); P. herrerai Machado-Allison on Desmodus rotundus (E. Geoffroy). P. iheringi Oudemans was collected from four species of bats (Artibeus cinereus (Gervais), A. jamaicensis Leach, A. literatus (Olfers), and Vampyrops lineatus (E. Geoffroy]. No spinturnicids were found on Carollia perspecillata (L.) or on molossid or vespertilionid bats.