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At least 145 records · Page 8Linked to original sources
PubMed2002

Phylogeography of the neotropical sand fly Lutzomyia longipalpis inferred from mitochondrial DNA sequences.

Sand flies in the Lutzomyia longipalpis species complex include the primary vector of Leishmania chagasi, the etiologic agent of visceral leishmaniasis in the Neotropics. Twelve L. longipalpis populations from South and Central America were compared using the cytochrome c oxidase I (COI) gene from the mitochondrial genome. The haplotype profiles for each population revealed that the majority of sequence variation was inter-population (98%) rather than intra-population, suggesting that sequence polymorphisms at the COI locus should provide excellent characters for the study of phylogenetic relationships among populations. Phylogenetic reconstruction using distance (neighbor-joining) and maximum parsimony analysis revealed the existence of four clades among the L. longipalpis populations studied: (1) Laran, (2) Brazilian, (3) cis-Andean and (4) trans-Andean. We suggest that these clades represent species. A biogeographical interpretation of the molecular phylogeny suggests that the process of speciation in the L. longipalpis complex began in the Pliocene, from a sub-Andean-Amazonian gene pool resulting from the Andean orogeny (formation of the East Andean Cordillera). The four clades probably diverged as a result of vicariance events that occurred throughout the late Pliocene and Pleistocene. We propose and discuss several historical scenarios, based on the biogeography and historical geology of Central and South America.

Animals↗
PubMed2002

Molecular phylogeny of French Guiana Hylinae: implications for the systematic and biodiversity of the Neotropical frogs.

In this study we used nucleotide sequences from a segment of mitochondrial 16S ribosomal DNA gene to investigate the evolutionary relationships of some French Guiana Hylinae. New sequences, representing the members of different French Guiana frogs-five specimens of the Scinax genus, two Hyla, one Osteocephalus, one Hyalinobatrachium and two Rana as out-group-were examined. In addition, 26 sequences available from GenBank database representing the other subfamilies of the Hylidae were added to our study. This work allowed us to clarify relationships within the four hylids subfamilies (Pelodryadinae, Phyllomedusinae, Hemiphractinae and Hylinae) and the phylogenetic placement of the enigmatic Scinax genus within the Hylidae. We found that: (1) the Scinax genus displays a high level of differentiation in comparison to two other genera (Litoria and Hyla) belonging to 'Hylidae' family; (2) the Hylinae are paraphyletic given the position of the Litoria, which was the sister-group of the Hyla and the Osteocephalus genera; (3) the anterior works and our results (based on two different data sets) showed the paraphyly of the Hylidae questioning the validity of this family; (4) the reassessment of these different taxonomic groups will induce a huge implication on the estimation (past, present and future) of the biodiversity (in Neotropical frogs).

Animals↗
PubMed2003

Perenniporiella gen. nov. segregated from Perenniporia, including a key to neotropical Perenniporia species with pileate basidiomes.

Perenniporiella gen. nov. is segregated from Perenniporia. The new combinations Perenniporiella neofulva and Perenniporiella micropora, and the new species Perenniporiella pendula are proposed. Perenniporia piperis and Perenniporia albida are considered as taxonomic synonyms of P. neofulva. The three species are described and their taxonomic position is discussed. A key to the neotropical Perenniporiella and Perenniporia species with pileate basidiomes is presented.

Basidiomycota↗
PubMed2005

Total synthesis of the neotropical poison-frog alkaloid (-)-205B.

[reaction: see text]. A stereocontrolled total synthesis of the neotropical poison-frog alkaloid (-)-205B (1) has been achieved, employing a dithiane three-component linchpin coupling, a one-pot sequential construction of the embedded indolizidine ring, and ring-closing metathesis (RCM) to arrive at the novel 8b-azaacenaphthylene ring system comprising the alkaloid. The synthesis proceeded with a longest linear sequence of 19 steps, affording (-)-1 in 5.6% overall yield.

Alkaloids↗
PubMed2000

A biodiversity approach in the neotropical erythrinidae fish, Hoplias malabaricus. Karyotypic survey, geographic distribution of cytotypes and cytotaxonomic considerations.

Hoplias malabaricus, a widely distributed neotropical freshwater fish, shows a conspicuous karyotypic diversification. An overview of this diversity is presented here comprising several Brazilian populations, and some others from Argentina, Uruguay and Surinam. Seven general cytotypes are clearly identified on the basis of their diploid number (2n = 39 to 2n = 42), chromosomal morphology and sex chromosome systems, which can be clustered into two major karyotypic groups. This clustering suggests that karyotype structure would be more informative than the diploid number regarding cytotype relationships in this fish group. While some cytotypes show a wide geographical distribution, some others appear to be endemic to specific hydrographic basins. Sympatric cytotypes can occur without detection of hybrid forms; this situation points to a lack of gene flow, a fact that is also reinforced by studies with genomic markers. The karyotypic data support the view that the nominal taxon H. malabaricus corresponds to a species complex comprising distinct evolutionary units, each with well-established chromosomal differences.

Animals↗
PubMed2001

Morphologically differentiated sex chromosomes in neotropical freshwater fish.

A general survey of the occurrence of morphologically differentiated sex chromosomes in the neotropical freshwater fishes is presented. The total number of 32 occurrences involving simple XX-XY and ZZ-ZW, and multiple X1X2Y, XY1Y2 and ZW1W2 sex chromosome systems is described, with comments on the aspects of sex chromosome evolution in this fish fauna. The occurrence of different sex chromosome systems in related species of the same genus, or in different populations of the same nominal species, involving male and sometimes female heterogamety, and differences in the molecular composition of sex-linked heterochromatin, are considered as indicative of the early stage of sex chromosomes evolution in fish.

Animals↗
PubMed2001

Two 5S rDNA arrays in neotropical fish species: is it a general rule for fishes?

In this paper we describe Southern blot hybridization results probed with 5S rRNA genes for several Neotropical fish species representing different taxonomic groups. All the studied species showed a general trend with the 5S rDNA tandem repeats organized in two distinct size-classes. At the same time, data on 5S rDNA organization in fish genome were summarized. Previous information on the organization and evolution of 5S rRNA gene arrays in the genome of this vertebrate group are in agreement with the Southern results here presented. Sequences obtained for several fish species have revealed the occurrence of two distinct 5S rDNA classes characterized by distinct nontranscribed spacer sequences, which are clustered in different chromosomes in some species. Moreover, the 5S rDNA loci are generally distributed in an interstitial position in the chromosomes and they are usually not syntenic to the 45S rDNA. The presence of two classes of 5S rDNA in several non-related fish species suggests that this could be a common condition for the 5S rRNA gene organization in the fish genome.

Animals↗
PubMed2005

Spatial genetic structure of two sympatric neotropical palms with contrasting life histories.

The spatial genetic structure within sympatric populations of two neotropical dioecious palm species with contrasting life histories was characterized to evaluate the influence of life history traits on the extent of genetic isolation by distance. Chamaedorea tepejilote is a common wind-pollinated arboreal understory palm. Chamaedorea elatior is an uncommon climbing subcanopy palm with entomophilous pollination syndrome. A total of 59 allozyme alleles for C. tepejilote and 53 alleles for C. elatior was analyzed using both unweighted (Iu) and weighted (Iw) Moran's I spatial autocorrelation statistics. The spatial genetic structure detected within these populations is consistent with those reported for highly dispersed plants. A significance test for differences between mean Moran's I-coefficients revealed less spatial genetic structure within the C. tepejilote population than that in the C. elatior population. Adjacent individuals of C. elatior exhibited significant spatial genetic autocorrelation (Iu=0.039, Iw=0.034), indicating a Wright's neighborhood size of about 100 individuals. For C. tepejilote, nonrandom genetic distribution among nearest neighbors was detected, even from small spatial autocorrelation values (Iu=0.008, Iw=0.009), consistent with a neighborhood size of about 300 individuals. For both species, seed dispersal, mortality among life cycle stages, overlapping generations, and contrasting traits of mating and reproduction influence the standing spatial genetic structure within populations.

Arecaceae↗
PubMed2005

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.

Genetic Markers↗
PubMed2005

Spatial genetic structure of Simarouba amara Aubl. (Simaroubaceae), a dioecious, animal-dispersed Neotropical tree, on Barro Colorado Island, Panama.

Simarouba amara (Simaroubaceae) is a vertebrate-dispersed, insect-pollinated Neotropical tree found in lowland moist forest from upper Mesoamerica to the Amazon basin. We assessed the spatial genetic structure of S. amara within the 50-ha Forest Dynamics Plot on Barro Colorado Island in the Republic of Panama. A total of 300 individuals were genotyped using five microsatellite loci, representing 100 individuals with a dbh>or=10 cm, 100 individuals of 1-10 cm dbh, and 100 individuals of <1 cm dbh. The 200 individuals in the two larger size classes were also genotyped with 155 AFLP loci. Spatial autocorrelation analysis using Moran's Index detected significant genotypic association at the smallest distance classes for 1-10 cm dbh (0-20 m) and >10 cm dbh (0-40 m) size categories. Significant spatial autocorrelations were detected over larger scales (0-140 m) in <1 cm dbh individuals. The relatively weak genetic structure of S. amara, in comparison to other recent studies, may be explained by pollen and seed dispersal over the 50 ha plot, overlapping seed shadows, and postrecruitment mortality.

Demography↗
PubMed2005

Genetic resource impacts of habitat loss and degradation; reconciling empirical evidence and predicted theory for neotropical trees.

The theoretical impacts of anthropogenic habitat degradation on genetic resources have been well articulated. Here we use a simulation approach to assess the magnitude of expected genetic change, and review 31 studies of 23 neotropical tree species to assess whether empirical case studies conform to theory. Major differences in the sensitivity of measures to detect the genetic health of degraded populations were obvious. Most studies employing genetic diversity (nine out of 13) found no significant consequences, yet most that assessed progeny inbreeding (six out of eight), reproductive output (seven out of 10) and fitness (all six) highlighted significant impacts. These observations are in line with theory, where inbreeding is observed immediately following impact, but genetic diversity is lost slowly over subsequent generations, which for trees may take decades. Studies also highlight the ecological, not just genetic, consequences of habitat degradation that can cause reduced seed set and progeny fitness. Unexpectedly, two studies examining pollen flow using paternity analysis highlight an extensive network of gene flow at smaller spatial scales (less than 10 km). Gene flow can thus mitigate against loss of genetic diversity and assist in long-term population viability, even in degraded landscapes. Unfortunately, the surveyed studies were too few and heterogeneous to examine concepts of population size thresholds and genetic resilience in relation to life history. Future suggested research priorities include undertaking integrated studies on a range of species in the same landscapes; better documentation of the extent and duration of impact; and most importantly, combining neutral marker, pollination dynamics, ecological consequences, and progeny fitness assessment within single studies.

Computer Simulation↗
PubMed1999

Intragenomic heterogeneity of a ribosomal DNA spacer (ITS2) varies regionally in the neotropical malaria vector Anopheles nuneztovari (Diptera:Culicidae).

We investigated intragenomic heterogeneity of ITS2 within twenty individual Anopheles nuneztovari (subgenus Nyssorhynchus) from five geographical localities in the neotropics (three from Brazil and one each from Colombia and Venezuela) by cloning and sequencing PCR-amplified copies of this spacer. Intragenomic heterogeneity was observed in thirteen of twenty mosquitoes of both sexes from all localities. As estimated by uncorrected P, however, mean sequence divergence was greater in mosquitoes from Brazil (PR = 0.0100, BL = 0.0196, AB = 0.0182) than in those from Venezuela (SO = 0.0026) or Colombia (SI = 0.0078). Sequence divergence per genome was significantly higher in mosquitoes from Brazil than in those from SO and SI. In fact, divergence among ITS2 variants within single mosquitoes from the Brazilian localities was often as great as that between localities. Similarly, the number of variants per mosquito was significantly greater in Brazil (maximum of six variants) than in both SO and SI (maximum of two variants). These results indicate that homogenization of ITS2 has proceeded to a greater extent in SO and SI than in the localities in Brazil. The differences in intragenomic heterogeneity between both SO and SI versus the Brazilian localities probably reflect either differences in population-level processes such as gene flow and genetic drift, or the fact that these localities may represent two or more cryptic species, as suggested by other studies.

Animals↗
PubMed2000

Molecular systematics, biogeography and population structure of neotropical freshwater needlefishes of the genus Potamorrhaphis.

Phylogenetic relationships of populations and species within Potamorrhaphis, a genus of freshwater South American needlefishes, were assessed using mitochondrial cytochrome b sequences. Samples were obtained from eight widely distributed localities in the Amazon and Orinoco rivers, and represented all three currently recognized species of Potamorrhaphis. The phylogeny of haplotypes corresponded imperfectly to current morphological species identities: haplotypes from P. guianensis, the most widespread species, did not make up a monophyletic clade. Geography played a strong role in structuring genetic variation: no haplotypes were shared between any localities, indicating restricted gene flow. Possible causes of this pattern include limited dispersal and the effects of current and past geographical barriers. The haplotype phylogeny also showed a complex relationship between fishes from different river basins. Based on the geographical distribution of clades, we hypothesize a connection between the middle Orinoco and Amazon via rivers of the Guianas. More ancient divergence events may have resulted from Miocene alterations of river drainage patterns. We also present limited data for two other Neotropical freshwater needlefish genera: Belonion and Pseudotylosurus. Pseudotylosurus showed evidence of substantial gene flow between distant localities, indicating ecological differences from Potamorrhaphis.

Animals↗
PubMed2000

Chloroplast diversity in Vouacapoua americana (Caesalpiniaceae), a neotropical forest tree.

The chloroplast genome has been widely used to describe genetic diversity in plant species. Its maternal inheritance in numerous angiosperm species and low mutation rate are suitable characters when inferring historical events such as possible recolonization routes. Here we have studied chloroplast DNA variation using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) with seven pairs of primers and four restriction enzymes in 14 populations of Vouacapoua americana (Caesalpiniaceae) a neotropical tree sampled throughout French Guiana. Population diversity (Hs), total gene diversity (Ht) and differentiation among populations (GST) were estimated using Nei's method as 0.09, 0.87 and 0.89, respectively. This is consistent with the limited gene flow associated with synzoochory in this species. The genetic structure observed in the north of French Guiana suggests that historical events such as contractions and recent recolonizations have had a large impact on the distribution of genetic diversity in this species.

Chloroplasts↗
PubMed2002

Evidence of low gene flow in a neotropical clustered tree species in two rainforest stands of French Guiana.

The spatial genetic structure of the neotropical, clustered tree species Vouacapoua americana (Aublet) was studied in two natural forest stands (Paracou and Nouragues) in French Guiana. Using eight microsatellite loci, V. americana is characterized by a marked genetic structure at small spatial distances (under 30-60 m), in agreement with the limited seed dispersal by rodent species. Gene flow through pollen is also shown to be mainly restricted to less than 100 m. This result suggests that most pollination events (mediated through small insects) are probably limited to within-patches of individuals, which might explain the high genetic differentiation among patches (F(ST) = 0.11) separated by less than 2 km. We also assume that stronger genetic structure in Paracou is likely to be due to lower seed dispersal by rodents, large spatial distances separating patches, or a recent recolonization event.

DNA, Plant↗
PubMed2003

Combining genetic markers and stable isotopes to reveal population connectivity and migration patterns in a neotropical migrant, Wilson's warbler (Wilsonia pusilla).

We used results from the analysis of microsatellite DNA variation and hydrogen stable-isotope ratios to characterize the population structure of a neotropical migrant passerine, the Wilson's warbler (Wilsonia pusilla). The resulting information was then used to infer migration patterns and population connectivity between breeding grounds in North America and overwintering areas in Mexico and Central America. The microsatellite data revealed genetic structure across the North American continent; populations in the west were found to significantly differ from the east. Minimal genetic structure was observed among western sites. The lack of isolation by distance and low variance in FST values suggests that gene flow could play an ongoing role in limiting genetic differentiation among sites in the western part of the distribution. However, additional information including estimates of effective population size and the proximity of the population to equilibrium is required before the role of gene flow can be assessed fully. Analysis of isotope data showed a negative relationship between latitude and hydrogen isotope ratios in breeding ground individuals. There was a positive relationship between wintering ground latitude and hydrogen isotope ratios for individuals that were genetically western in origin. This is consistent with a leapfrog pattern of migration, in which genetically western birds from the northernmost breeding areas overwinter at the most southerly locations in Central America. Additionally, isotopic ratios of western birds suggest that coastal breeders overwinter in western Mexico, while western birds from further inland and at high elevations overwinter in eastern Mexico. Using information from both genetic an isotopic approaches will probably be useful for identifying patterns of migration and population connectivity between breeding and overwintering areas, both important issues for conservation efforts, and may also contribute to investigation of the evolution of migration.

Animal Migration↗
PubMed2003

Historical biogeography of the catfish genus Hypostomus (Siluriformes: Loricariidae), with implications on the diversification of Neotropical ichthyofauna.

Tropical South America possesses the largest ichthyofauna of any continental region. To test whether palaeohydrological changes may have been the causes of such diversification, the 'hydrogeological' hypothesis, the phylogenetic relationships of 51 representatives of the catfish genus Hypostomus (Siluriformes: Loricariidae) were inferred using mitochondrial D-loop haplotype sequences. Specimens were collected in all main tropical South American rivers systems east to the Andes. The major interrelationships found with the D-loop data were confirmed with a subset of 21 species using complete internal transcribed spacer (ITS) region sequences. The phylogenetic analysis indicate that the genus Hypostomus can be divided into four monophyletic clades. The historical biogeographical analysis of each of these clades allows the identification of seven major cladogenetic events. Using calibrated D-loop and ITS molecular clocks, date estimations were attributed to each of these cladogenetic events allowing a linkage between four of them with documented hydrogeological changes. Comparisons with published distribution patterns of unrelated fish groups indicate that several of the reconstructed and dated hydrogeological-cladogenetic events may have acted at a large scale on the diversification of Neotropical freshwater fish fauna during late Tertiary.

Animals↗
PubMed2002

Periaqueductal gray and the region of the paralemniscal area have different functions in the control of vocalization in the neotropical bat, Phyllostomus discolor.

The periaqueductal gray matter and the region of the paralemniscal area were neuroanatomically delineated in the brain of the neotropical bat Phyllostomus discolor[Wagner (1843) Arch. Naturgesch., 9, 365-368] and were probed with electrical microstimulation for eliciting vocalizations. In a well-delimited rostral portion of the periaqueductal gray exclusively, communication calls could be triggered at low stimulation currents. Communication calls as well as echolocation calls could be elicited at the dorsal and ventral edges of this area. Pharmacological stimulation with microdialysed kainic acid in this particular periaqueductal gray area demonstrated that neurons and not fibres of passage are activated for triggering vocalization. Solely echolocation calls were emitted upon electrical microstimulation or with microdialysed kainic acid in the region of the paralemniscal area. The periaqueductal gray appears to be involved in vocal pathways that control both communication calls and echolocation calls, while the region of the paralemniscal area seems to be specialized for control of echolocation calls only. Respiration is similarly influenced by stimulation in the periaqueductal gray and the region of the paralemniscal area. Periaqueductal gray and paralemniscal area interact differently with the final common pathway for vocalization, and may represent different functional organization in the vocal controlling pathways for communication calls and echolocation calls.

Animals↗