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PubMedDate not supplied

Evidence for a neotropical origin of Leishmania.

Contradictory biogeographic hypotheses for either a Neotropical or a Palaearctic origin of the genus Leishmania have been proposed. Hypotheses constructed on the basis of biogeographic data must be tested against an independent dataset and cannot be supported by biogeographic data alone. In the absence of a fossil record for the Leishmania these two hypotheses were tested against a combined dataset of sequences from the DNA polymerase A catalytic subunit and the RNA polymerase II largest subunit. The phylogeny obtained provided considerable support for a Neotropical origin of the genus Leishmania and leads us to reject the hypothesis for a Palaearctic origin.

Animals↗
PubMed2002

Araucnephia iberaensis n. sp., a neotropical black fly with a peculiar distribution (Diptera-Simuliidae).

Araucnephia Wygodzinsky & Coscarón is a Neotropical black fly genus in which only one species from Central Chile is known. Another species has now been found in Corrientes province on the eastern side of the Iberá tropical swamps of Argentina, on the western border of the mountainous region of southern Brazil. This new species, A. iberaensis, is herein described and illustrated and information on its bionomics is recorded. It is an interesting species because previous to its discovery no black fly genus or subgenus from Central Chile region has been found in tropical areas, because these two regions are separated by the Monte and Pampas realms. Similarly, no Brazilian genus or subgenus has crossed the Andes mountains to Chile. A comparison with other Neotropical, Nearctic, Ethiopian (Afrotropical) and Australian Prosimuliini (sensu Crosskey & Howard) showed Araucnephia to be a valid taxon most closely related to Araucnephioides (sympatric in Chile). Araucnephia also shows great affinities with Lutzsimulium from Southeast Brazil and Argentina and Paracnephia from South Africa.

Animals↗
PubMed2006

Distribution patterns of Neotropical primates (Platyrrhini) based on Parsimony Analysis of Endemicity.

The Parsimony Analysis of Endemicity (PAE) is a method of historical biogeography that is used for detecting and connecting areas of endemism. Based on data on the distribution of Neotropical primates, we constructed matrices using quadrats, interfluvial regions and pre-determinated areas of endemism described for avians as Operative Geographic Units (OGUs). We codified the absence of a species from an OGU as 0 (zero) and its presence as 1 (one). A hypothetical area with a complete absence of primate species was used as outgroup to root the trees. All three analyses resulted in similar groupings of areas of endemism, which match the distribution of biomes in the Neotropical region. One area includes Central America and the extreme Northwest of South America, other the Amazon basin, and another the Atlantic Forest, Caatinga, Cerrado and Chaco.

Animals↗
PubMed2000

Phylogenetic relationships among species of Stilestrongylus Freitas, Lent and Almeida, 1937 (Trichostrongyloidea: Heligmonellidae: Nippostrongylinae), parasites of myomorph rodents (Rodentia: Muridae) in the Neotropics.

The phylogenetic relationships of 14 species of Stilestrongylus were analyzed using the comparative morphology of 21 characters. We obtained 2 shortest trees of 50 steps, with a consistency index of 0.540 and 25 apomorphic character states. Ingroup monophyly was supported on these trees by 2 and 3 synapomorphies, respectively, and the ingroup was defined by the following characters: greater number of ventral ridges relative to the number of ridges dorsally, asymmetric bursa, and externodorsal rays differing in size. Sister-group relationships among Stilestrongylus and the other genera designated as outgroups are relatively consistent with those postulated by Durette-Desset's in a classification of the Nippostrongylinae. The ancestor of the species groups comprising Hassalstrongylus, Guerrerostrongylus, and Stilestrongylus originated and diversified in murids in the Neotropical region. Species of Hassalstrongylus occur in rodents between southeastern North America and the eastern part of South America (Brazil and Argentina), whereas species of Guerrerostrongylus and Stilestrongylus diversified exclusively in rodents in the Neotropics.

Animals↗
PubMed2004

New Wolbachia endosymbionts from Nearctic and Neotropical fleas (Siphonaptera).

Several species of fleas (Siphonaptera), ectoparasites of mammals and birds, have recently been shown to harbor species of Wolbachia. Here, we extend this data set to 20 more species of Siphonaptera (Rhopalopsyllidae, Stephanocircidae, Pulicidae, Ceratophyllidae, Ctenophthalmidae, Ischnopsyllidae, Leptopsyllidae, and Malacopsyllidae) from sylvatic populations throughout the Nearctic and Neotropical regions. Using polymerase chain reaction, we targeted the Wolbachia 16S ribosomal DNA (rDNA) gene. Applying maximum parsimony- and maximum likelihood-based algorithms, as well as statistical parsimony, we conducted a phylogenetic analysis of Wolbachia 16S rDNA to evaluate its position within the known Wolbachia spp. The analysis recovered the siphonapteran Wolbachia 16S rDNA sequences as a monophyletic group and shows multiple haplotype connections between the Neotropical and Nearctic Wolbachia strains of fleas.

Animals↗
PubMedDate not supplied

A technique for extraction and thin layer chromatography visualization of fecal bile acids applied to neotropical felid scats.

Fecal bile acid patterns have been used successfully to identify scats. Neotropical felid scats are capable of this biochemical identification because they present low concentrations of plant pigments that would interfere in fecal bile acids detection. However, neotropical felid scats have poor quantities of bile acids, so we developed in this work a proper technique for their extraction, visualization and determination. Twenty eighth feces of seven different felid species, collected from Zoological and Wildlife Parks, were dried and pulverized. The procedure for analyzing feces is: Take one g of pulverized feces and shake for 3 hr at room temperature in 20 ml benzene:methanol; filter and evaporate to 5 ml. Spot on TLC plate and develop in toluene:acetic acid:water. Dry and visualize with anisaldehyde. Field collected scats could be identified by the bile acids pattern revealed by this specific technique and, then, used as a source of information for distribution, density and food habits studies.

Animals↗
PubMed1996

[Claves ilustradas para las subfamilias, tribus y géneros de esfécidos neotropicales (Apoidea: Sphecidae) [Illustrated clues for subfamilies, tribes, and genera of neotropical Spheciade (Apoidea:Sphecidae)].

141 genera of Sphecidae, representing 1,628 species, are known from the Neotropical Region. Illustrated keys to genera, tribes, and subfamilies are presented in Spanish and English. These have been modified and updated from those in Bohart & Menke's 1976 book, Sphecid Wasps of the World. The validity of a few genera recognized by Bohart & Menke is now in question and the keys are annotated to alert users to these problems. A list of neotropical genera and higher taxa is included. Names in the list are appended with significant literature published since 1976. The history and current status of subfamilies are reviewed. Ten subfamilies are recognized. Family characters and biology are summarized. Morphological terms are illustrated and a glossary provided.

Animals↗
PubMed1998

Seed dispersal by neotropical seed predators.

From a plant's perspective, the difference between a seed predator and a seed disperser should be straightforward: attract animals that will disperse seeds and defend seeds from potential predators. Unlike pulp-eating frugivores, seed predators regularly encounter diverse plant protective mechanisms. The purpose of this paper is to examine feeding constraints, morphological adaptations, and the mechanical process of seed predation. While there is evidence that some seed predators cause severe losses to seed crops, there is also evidence that seed predators enhance seed dispersal and germination. We also examine four methods by which neotropical seed predators may contribute to dispersal. 1) Seed predators examined here ingested fruit when seeds were full-sized, but not yet mature (i.e., seeds of mature fruit may be avoided by seed predators and available for dispersal by other frugivores). 2) Sympatric seed predators may ingest seeds from different plants thus reducing overall predator load on any individual plant. 3) Seed predators that manipulate seeds (e.g., remove pericarp and seed coat) may enhance germination if the prepared seeds are dropped, discarded, or buried and not ingested. 4) Small seeds may miss mastication and swallowed intact with a food bolus. The last mechanism is the most likely to contribute to seed dispersal by the widest array of vertebrate seed predators, but primate seed predators may facilitate seed dispersal using all four mechanisms. Therefore, the traditional dichotomy of seed predator vs. seed disperser oversimplifies the interactions between seed predators and plants.

Animals↗
PubMed2000

When will the stork arrive? Patterns of birth seasonality in neotropical primates.

We review and discuss the ultimate and proximate causes of birth seasonality in Neotropical primates and the seasonal patterns shown by each genus within this group. Our review of the literature shows that most New World monkey populations studied so far show some degree of birth seasonality. Photoperiod is the most important proximate cue used by populations living at relatively high latitudes to time their reproductive events, but almost nothing is known about the proximate factors used by those near the equator. The findings are consistent with the hypothesis that food availability is the most important ultimate cause of birth seasonality. Predation seems to promote birth synchrony in some species (e.g., squirrel monkeys). Multiple regression ANCOVA was used to estimate how the degree of birth seasonality is affected by ecological and life history variables. The ANCOVA model shows that three factors affect the degree of birth seasonality: diet, latitude, and body size. Folivores (howlers) are less seasonal than frugivores and insectivores. The degree of seasonality increases with latitude and shows a humped relationship with body size, peaking at 1.66 kg body mass. This last relationship was expected since small bodied species have to pay a cost (in terms of time lost) by being seasonal on a yearly basis, and large species are buffered against fluctuations in food availability due to their large body mass. To understand which of three alternative birth strategies is followed by each species (reduce energy stress during peak lactation, wean infants during peak food availability, or store reserves during peak energy availability), we compared the location of the birth peak in relation to the peak in food-availability for those populations from which data were available. Most species conform to the typical pattern of births concentrated before the peak in food availability, allowing peak lactation (small-sized species) or weaning (capuchins) to take place before the start of the lean season. The pattern of births of the atelines is consistent with the weaning hypothesis. However, since they give birth during the lean season, this pattern is also consistent with an alternative strategy.

Analysis of Variance↗
PubMed1998

Haemorrhagic activity of neotropical rattlesnake (Crotalus vegrandis Klauber, 1941) venom.

In this work we have demonstrated for the first time in any Venezuelan Crotalus, haemorrhagic activities that are present in the Neotropical Uracoan rattlesnake (Crotalus vegrandis) venom. This venom has been little studied, perhaps because the snake is restricted to a small habitat located in the dry savannahs of northeastern Venezuela. In our experiments Crotalus vegrandis venom caused a very evident haemorrhagic area consisting of approximately 2/3 diameter of the area caused by a positive control Bothrops lanceolatus venom. Crotalus vegrandis venom affects blood coagulation and causes intense haemorrhages. It does not clot fibrinogen, therefore it has neither thrombin-like activity which transforms fibrinogen to fibrin nor procoagulant enzymatic function which produces thrombin. On the other hand, it degrades fibrinogen making it incoagulable to thrombin. The venom, when injected in the animals, resulted in a high increase of the Partial Time of Thromboplastin (PTT) tests. It is interesting to observe that the haemorrhagic capacity in the Crotalus genus (widely distributed in the American continent) increases from south to the north, being present in North American Crotalus, a venom with wide haemorrhagic activities, and almost non-existent in most of the South American Crotalus species and subspecies.

Animals↗
PubMed2003

Functional morphology of extreme jaw protrusion in Neotropical cichlids.

The New World cichlids Petenia splendida and Caquetaia spp. possess extraordinarily protrusible jaws. We investigated the feeding behavior of extreme (here defined as greater than 30% head length) and modest jaw-protruding Neotropical cichlids by comparing feeding kinematics, cranial morphology, and feeding performance. Digital high-speed video (500 fps) of P. splendida, C. spectabile, and Astronotus ocellatus feeding on live guppy prey was analyzed to generate kinematic and performance variables. All three cichlid taxa utilized cranial elevation, lower jaw depression, and rotation of the suspensorium to protrude the jaws during feeding experiments. Extreme anterior jaw protrusion in P. splendida and C. spectabile resulted from augmented lower jaw depression and anterior rotation of the suspensorium. Morphological comparisons among eight cichlid species revealed novel anterior and posterior points of flexion within the suspensorium of P. splendida and Caquetaia spp. The combination of anterior and posterior loosening within the suspensorium in P. splendida and Caquetaia spp. permitted considerable anterior rotation of the suspensorium and contributed to protrusion of the jaws. Petenia splendida and C. spectabile exhibited greater ram distance and higher ram velocities than did A. ocellatus, resulting primarily from increased jaw protrusion. Petenia splendida and C. spectabile exhibited lower suction feeding performance than A. ocellatus, as indicated by lower suction-induced prey movements and velocities. Thus, extreme jaw protrusion in these cichlids may represent an adaptation for capturing elusive prey by enhancing the ram velocity of the predator but does not enhance suction feeding performance.

Adaptation, Biological↗
PubMed1983

Alteration of blood coagulation and complement system in neotropical primates infected with Junin virus.

The neotropical primate Callithrix jacchus infected with Junin virus presented an acute disease with hematological and neurological manifestations and died 17 to 24 days after infection. This picture is similar to that of human Argentine hemorrhagic fever (AHF). Blood coagulation and complement studies were performed in ten C jacchus animals inoculated with 10(3) TCID50 of Junin virus, the prototype pathogenic XJ strain. Four monkeys were used as normal controls. Infected monkeys and normal controls were bled to death on days 7, 14, 17, and 21. A progressive decrease in the number of platelets was found after day 7 of infection. On day 21, the last monkey had a value of 24,000/microliters. The levels of blood clotting factors did not change until day 17, when a shortened partial thromboplastin time activated with Kaolin (PTTK) (36 sec) and increased factors VIII (192.2%) and VII-X (266.6%) were found. On day 21, the PTTK was prolonged (50.7 sec) and factors II, V, and VIII, were decreased. Thrombin time was found prolonged from day 14 onward. Fibrinogen and fibrin degradation products (FDPs) were increased on days 17 (754 mg/dl and 9.2 microliters/ml) and 21 (457 mg/dl and 29.4 micrograms/ml). No changes in the levels of alpha 2 macroglobulin were observed. Complement hemolytic levels were found to be low on day 7 (58.3 UCH50, increased on day 14 (165.1), and within normal range at the end of infection (107.2). C3 levels showed a similar pattern. The bone marrow was active and hypercellular, and the number and morphology of megakaryocytes were normal in all but one of infected animals. The results of blood clotting suggest a limited activation. The complement system presented a profile of activation followed by a rebound phenomenon. The activation of complement appeared ten days before the alteration of the clotting system was evident.

Animals↗
PubMed1998

Social constraints on the onset of incubation in a neotropical parrot: a nestbox addition experiment

We examined whether the early onset of incubation serves to protect eggs from the dangers imposed by conspecifics in the green-rumped parrotlet, Forpus passerinus, a small neotropical parrot that lays a large clutch and begins incubation on the first egg. Nestboxes with eggs were installed and their fate was followed for 72 h to determine whether egg destruction and nest site take-overs occurred as predicted by the Egg Protection and Limited Breeding Opportunities Hypotheses, or whether additional eggs appeared in the boxes as predicted by the Brood Parasitism Hypothesis. Eggs were destroyed at 40.6% of 69 experimental boxes but at only 4.5% of control nests occupied by laying pairs. No eggs were laid in the experimental boxes. Egg destruction at experimental nests occurred during daylight hours and all mortality was caused by green-rumped parrotlets. Over 75% of the nests were destroyed by male-female pairs prospecting for nest sites, and the remainder were destroyed by male-male pairs. Lone males never destroyed eggs, although they frequently visited experimental boxes. Two of three failures at control nests were the result of nocturnal predators, and the other nest was apparently destroyed by parrotlets. There was no significant difference between experimental and control boxes in the frequency of visitations by lone males, male-female pairs and male-male pairs. Although experimental boxes that parrotlets visited were discovered quickly after placement, parrotlets were usually slow to enter them (X=5.8 h after discovery, range 0.3-23.5 h). Control nests were rarely left unattended: females spent nearly 75% of their time in the box, and pairs were typically absent for short intervals (median=7.5 min). Control females responded to intruding parrotlets by remaining in the box 94% of the time when alone, whereas males actively displaced and chased intruding parrotlets 66% of the time. Parrotlets that visited control nests approached the box significantly less often than those visiting experimental boxes. To ensure the survival of eggs, parrotlet parents must begin incubating eggs or guarding nests soon after laying to minimize destruction of clutches, loss of nest sites, a decline in the viability of their eggs and the time that all nestlings are exposed to predators. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1999

Changes in patterns of corticosterone secretion concurrent with migratory fattening in a neotropical migratory bird.

Several studies on free-living birds have shown a change in corticosterone secretion (elevated baseline levels and a reduced corticosterone response to stress) during migration. It was not known, however, if this change was concurrent with the development of migratory condition or if it was an independent response to unknown environmental stressors experienced by the birds prior to capture. In this study, a Neotropical annual migrant, the yellow-rumped warbler (Dendroica coronata), held under controlled laboratory conditions, was used to test the Migration Modulation Hypothesis (MMH): during the migratory period migrants exhibit (1) elevated baseline corticosterone to facilitate migratory fattening and (2) a reduced corticosterone stress response, a means by which skeletal muscle needed for migration can be protected against catabolism by high levels of corticosterone. Fifteen hatching-year warblers were maintained on insect larvae and water ad libitum for 43 weeks, experiencing two transitions from a short- to long-day photoperiod to bring them into spring migratory condition. Corticosterone profiles comprising three blood samples from each individual (baseline at the time of initial disturbance and 30 and 60 min later), body mass, fat reserves, molt, and state of cloacal protuberance (males only) were measured at key intervals throughout the study. Over the entire study, mean baseline corticosterone levels were positively correlated with mean body mass, which increased predictably in response to long days. Individual baseline corticosterone was not correlated with individual body mass at any time. During periods when the birds were lean and held on short days, the corticosterone stress profiles were characterized by low initial hormone concentration followed by a significant increase in corticosterone with handling time. In response to long days, the warblers showed a significant increase in body mass and fat reserves concurrent with corticosterone stress profiles characterized by significantly elevated baseline levels and no further increase in corticosterone with handling time. These results support both components of the MMH illustrating changes in corticosterone secretion concurrent with migratory fattening but the exact nature of this change is unknown.

Adipose Tissue↗
PubMed2001

Observations on serum 25-hydroxyvitamin D and calcium concentrations from wild-caught and captive neotropical bats, Artibeus jamaicensis.

Most bats of the suborder Microchiroptera are nocturnal, actively avoid sunlight, and eat mineral-poor diets. In those bats previously studied with respect to mineral metabolism, extensive bone remodeling occurs, and it has been suggested that calcium has been an important constraint on reproduction. There have been no previous studies of vitamin D or its metabolites in microchiropteran bats with respect to calcium metabolism. Reported is the utilization of current advances for the determination of serum levels of the vitamin D metabolite 25-hyroxyvitamin D (25-OH-D) in a neotropical bat, Artibeus jamaicensis. Serum from wild-caught animals contained low levels of 25-OH-D (5.6 +/- 3.0 ng/ml, n = 8). Bats maintained on a vitamin-D-supplemented diet had higher serum 25-OH-D levels and when the diet containing vitamin D was discontinued, mean serum 25-OH-D levels declined significantly after 6 months. Serum calcium concentrations in wild-caught bats (8.5 +/- 0.4 mg%) showed very little variation and were not significantly different in any of the vitamin-D-supplemented animals. A pairwise correlation analysis between 25-OH-D and serum calcium levels revealed no linear correlation. The results indicate either that 25-OH-D does not appear to play a key role or that low levels of 25-OH-D may be adequate in regulating serum calcium levels in this bat.

25-Hydroxyvitamin D 2↗
PubMed1997

Mitochondrial DNA sequencing reveals extreme genetic differentiation in a cryptic species complex of neotropical pseudoscorpions.

The neotropical pseudoscorpion Cordylochernes scorpioides (Chernetidae: Lamprochernetinae) is currently described as a single species ranging from Central America to northern Argentina. However, interpopulation crosses have recently demonstrated that C. scorpioides actually represents a complex of cryptic species. Here we present mitochondrial COI gene sequence data from C. scorpioides individuals from Panama, Trinidad, and French Guiana which demonstrate little or no intrapopulation variability but divergence ranging from 2.6 to 13.8% between geographic populations. Phylogenetic analysis provides evidence of a major split between C. scorpioides lineages from Central and South America. Levels of interpopulation mtDNA divergence correspond well with previously established patterns of postzygotic reproductive incompatibility between geographically distinct units within the C. scorpioides complex. By contrast, multivariate morphometric analysis demonstrates that extensive sequence divergence has occurred in the absence of appreciable morphological differentiation between the populations. To provide a framework for assessing the scale of geographic divergence in C. scorpioides, Cordylochernes sequences were compared with homologous sequence from its presumed sister taxon, Lustrochernes, and from Parachernes and Semeiochernes, representatives of the second chernetid subfamily, the Chernetinae. Our preliminary, generic-level analysis suggests that COI sequence data may prove useful in resolving relationships within this problematic family.

Animals↗
PubMed1997

Molecular systematics of tanagers (Thraupinae): evolution and biogeography of a diverse radiation of neotropical birds.

The tanagers (Passeriformes: Emberizidae: Thraupinae) are a diverse group of mostly Neotropical birds with a wide range of feeding morphologies, behaviors, plumage patterns and colors, and habitat preferences. Phylogenetic relationships of genera in this lineage were investigated using cytochrome b sequence data. This study indicates that the genera Euphonia and Chlorophonia (traditionally considered part of Thraupinae) do not form a monophyletic group with the other tanagers. Within the rest of Thraupinae, several monophyletic groups are identified that agree with traditional sequential taxonomies. Other monophyletic groups provide novel interpretations of biogeographic patterns and morphological evolution within tanagers. In several lineages, plumage patterns and colors persist despite dramatic changes in bill morphology. Phylogenetic structure and estimated timings of divergence events indicate that tanagers probably originated on Caribbean islands and later diversified throughout Central and South America during the mid-Tertiary.

Animals↗
PubMed1998

Phylogeny of neotropical monkeys: the interplay of morphological, molecular, and parasitological data.

Separate independent hypotheses of the phylogenetic relationships among the Platyrrhini monkeys have been produced in a recent past, either based upon morphological or molecular data, but the results are generally conflicting and the phylogeny of the group still is debated. The high host specificity observed among primates and their oxyurid parasites allows to consider the result of a morphologically based cladistic analysis of the pinworms of the Platyrrhini as an estimate of the phylogeny of these monkeys. Using the matrix representation method this "parasite-tree" is combined, using parsimony analysis, with several conflicting molecular or morphological hypothesis of the phylogeny of the host group. The results are discussed with respect to previously published classification, or composite computations of the phylogeny, of the Neotropical monkeys. Comparison of different hypothesis makes apparent several stable groups: (i) the Callithrichidae + Saimiri, (ii) the Atelidae/Alouattidae, (iii) the Pitheciidae, and (iv) the Alouattidae/Atelidae + Pitheciidae. In addition, the parasite and the molecular trees support close relationships between Callimico and Callithrix/Cebuella. The study also makes apparent that the parasite tree generally portrays the results of other studies, both when they are congruous and when they are conflicting. This is interpreted to be additional evidence for close coevolution between the Platyrrhini and their specific pinworms. Because, whatever the combination of data being considered no consensus can be found on the exact position of Aotus and Callicebus, and because it is likely that the earliest radiation of the Platyrrhini could be comparable to an evolutionary burst, which renders identification of homologous characters difficult, it is suggested that, possibly, not enough discriminating tracks of the evolutionary paths have been conserved to allow to resolve this uncertainty in the future.

Alouatta↗