Historical diversification of birds in Northwestern South America: A molecular perspective on the role of vicariant events

Studies of South American biodiversity have identified several areas of endemism that may have enhanced historical diversification of South American organisms. Hypotheses concerning the derivation of birds in the Choco area of endemism in northwestern South America were evaluated using protein electrophoretic data from 14 taxonomically diverse species groups of birds. Nine of these groups demonstrated that the Choco area of endemism has a closer historical relationship to Central America than to Amazonia, a result that is consistent with phytogeographic evidence. Within species groups, genetic distances between cis-Andean (east of the Andes) and trans-Andean (west of the Andes) taxa are, on average, roughly twice that between Choco and Central American taxa. The genetic data are consistent with the hypotheses that the divergence of most cis-Andean and trans-Andean taxa was the result of either the Andean uplift fragmenting a once continuous Amazonian-Pacific population (Andean Uplift Hypothesis), the isolation of the two faunas in forest refugia on opposite sides of the Andes during arid climates (Forest Refugia Hypothesis), or dispersal of Amazonian forms directly across the Andes into the trans-Andean region (Across-Andes Dispersal Hypothesis). Disentangling these hypotheses is difficult due to the complexity of the Andean uplift and to the scant geologic and paleoclimatic information that elucidates diversification events in northwestern South America. Regarding the divergence of cis- and trans-Andean taxa, the genetic, geologic, and paleoclimatic data allow weak rejection of the Andean Uplift Hypothesis and weak support for the Forest Refugia and Andean Dispersal Hypotheses. The subsequent diversification of Choco and Central American taxa was the result of Pleistocene forest refugia, marine transgressions, or parapatric speciation

Effect of river size on Amazonian primate community structure: a biogeographic analysis using updated taxonomic assessments

The mechanisms that underlie the diversification of Neotropical primates remain contested. One mechanism that has found support is the riverine barrier hypothesis (RBH), which postulates that large rivers impede gene flow between populations on opposite riverbanks and promote allopatric speciation. Ayres and Clutton‐Brock (1992) demonstrated that larger Amazonian rivers acted as barriers, delineating the distribution limits of primate species. However, profound changes in taxonomy and species concepts have led to the proliferation of Neotropical primate taxa, which may have reduced support for their results. Using the most recent taxonomic assessments and distribution maps, we tested the effect of increasing river size on the similarity of opposite riverbank primate communities in the Amazon. First, we conducted a literature review of primate taxonomy and developed a comprehensive spatial database, then applied geographical information system to query mapped primate ranges against the riverine geography of the Amazon watershed to produce a similarity index for opposite riverbank communities. Finally, we ran models to test how measures of river size predicted levels of similarity. We found that, almost without exception, similarity scores were lower than scores from Ayres and Clutton‐Brock (1992) for the same rivers. Our model showed a significant negative relationship between streamflow and similarity in all tests, and found river width significant for the segmented Amazon, but not for multiple Amazon watershed rivers. Our results support the RBH insofar as they provide evidence for the prediction that rivers with higher streamflow act as more substantial barriers to dispersal, and accordingly exhibit greater variation in community composition between riverbank

Genetic Applications in Avian Conservation

A fundamental need in conserving species and their habitats is defining distinct entities that range from individuals to species to ecosystems and beyond (Table 1; Ryder 1986, Moritz 1994, Mayden and Wood 1995, Haig and Avise 1996, Hazevoet 1996, Palumbi and Cipriano 1998, Hebert et al. 2004, Mace 2004, Wheeler et al. 2004, Armstrong and Ball 2005, Baker 2008, Ellis et al. 2010, Winker and Haig 2010). Rapid progression in this interdisciplinary field continues at an exponential rate; thus, periodic updates on theory, techniques, and applications are important for informing practitioners and consumers of genetic information. Here, we outline conservation topics for which genetic information can be helpful, provide examples of where genetic techniques have been used best in avian conservation, and point to current technical bottlenecks that prevent better use of genomics to resolve conservation issues related to birds. We hope this review will provide geneticists and avian ecologists with a mutually beneficial dialogue on how this integrated field can solve current and future problems

OBSERVATIONS ON THE CAMPO CERRADO AND FOREST AVIFAUNAS OF EASTERN DPTO. SANTA CRUZ BOLIVIA INCLUDING 21 SPECIES NEW TO THE COUNTRY

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Catalysis by palladium salts

A study has been made of the reductive carbonylation of 2,4-dinitrotoluene (2,4-DNT) to 2,4-diisocyanotoluene (2,4-TDI) with catalysis either by [Pd(isoquinoline)2], in the presence of Fe2O3 and MoO3 or of Fe2(MoO4)3 as cocatalysts, or by Pdo complexes without cocatalysts. In the case of catalytic systems based upon [Pd(isoquinoline)2Cl2] the reaction can be carried out at about 200\ub0C and under 200 atm of CO to produce 2,4-TDI with high conversions and acceptable selectivities. Pd0 complexes as catalysts good conversions can be achieved at much lower temperatures (100-120\ub0 C) but with a low selectivity when a higher pressure of CO is used (300 atm or more). An investigation of the reductive carbonylation of nitrobenzene to phenylisocyanate as a model system, together with a study of the thermal stability of [Pd(isoquinoline)2Cl2] in the presence of CO, has provided evidence that the actual active catalyst could be a reduced (probably zerovalent) form of palladium stabilised by the nitroaromatic substrate or by some of the products formed from it as ligands