16 research outputs found
DNA Fingerprinting Validates Seed Dispersal Curves from Observational Studies in the Neotropical Legume Parkia
Background: Determining the distances over which seeds are dispersed is a crucial component for examining spatial patterns of seed dispersal and their consequences for plant reproductive success and population structure. However, following the fate of individual seeds after removal from the source tree till deposition at a distant place is generally extremely difficult. Here we provide a comparison of observationally and genetically determined seed dispersal distances and dispersal curves in a Neotropical animal-plant system. Methodology/Principal Findings: In a field study on the dispersal of seeds of three Parkia (Fabaceae) species by two Neotropical primate species, Saguinus fuscicollis and Saguinus mystax, in Peruvian Amazonia, we observationally determined dispersal distances. These dispersal distances were then validated through DNA fingerprinting, by matching DNA from the maternally derived seed coat to DNA from potential source trees. We found that dispersal distances are strongly rightskewed, and that distributions obtained through observational and genetic methods and fitted distributions do not differ significantly from each other. Conclusions/Significance: Our study showed that seed dispersal distances can be reliably estimated through observational methods when a strict criterion for inclusion of seeds is observed. Furthermore, dispersal distances produced by the two primate species indicated that these primates fulfil one of the criteria for efficient seed dispersers. Finally, our stud
Genetic consequences of multigenerational and landscape colonisation bottlenecks for a neotropical forest pioneer tree, Vochysia ferruginea
Deforestation and abandonment of neotropical agricultural land has led to rapid exploitation by pioneer species. As recolonised populations may be founded by a limited number of individuals, there is significant potential for genetic
bottlenecks. Previous studies of pioneer tree dynamics have failed to consider population density interactions (by sampling populations with different densities)and the multigenerational consequences of recolonisation. In this paper we examine the genetic outcomes of a clearance / recolonisation regime for a Costa Rican long-lived pioneer species, Vochysia ferruginea, at a series of sites with
different densities and across multi-generational cohorts (old growth forest,secondary forest and seedlings) using variation for amplified fragment length polymorphism (AFLPs) and single sequence repeats (SSRs, microsatellites). A clearance/recolonisation phase was found to significantly increase fine-scale genetic structuring (average intensity of spatial genetic structure, Sp [SSR] = 0.0358) compared to old growth forest (Sp = 0.0126), and significantly reduces genetic diversity (Shannon’s index [AFLP] = 0.202 and 0.271–0.355 for other forest histories following density correction), which compounds over generations (e.g. at Tirimbina: old growth forest, allelic richness, RT [SSR] = 8.86; secondary forest RT = 7.95; seedlings RT = 4.76). Spatial structuring of closely related individuals suggests that V. ferruginea colonises sites via early invaders, which establish patches with half sib relationship. The variability observed between cohorts for genetic differentiation and inbreeding coefficients suggests that the presence of remnant trees can have an important impact on the genetic make up of recolonised populations. One main concern from these
results is that if secondary forest blocks harbour reduced genetic diversity and persist in the landscape, then species like V. ferruginea may be forced into a downward spiral of diversity loss if old growth remnants, which harbour higher diversity, are cleared and secondary blocks are used as reforestation sources
Life after disturbance (I): changes in the spatial genetic structure of Jacaranda copaia (Aubl.) D. Don (Bignonianceae) after logging in an intensively studied plot in French Guiana
International audienceKey message Forest disturbance affects the within-population distribution of genetic diversity, but not its overall levels, in a tropical pioneer tree species. In particular , clumps of related saplings with impoverished diversity are found in canopy gaps but not under forest cover. Context Forest disturbances can have long-term consequences on the genetic structure of tree populations, because they can alter the demographic properties of the regeneration process and favour some subpopulations/genotypes, both by stochastic processes and by selection. Intermediate disturbances tend to favour species diversity, at least in highly diverse communities , but their effect on intra-specific diversity is unknown. Aims In this study, we have looked at the genetic consequences of forest disturbance in a stand of the long-lived Neo-tropical pioneer species, Jacaranda copaia. Methods The study site was experimentally logged in 1984, and the canopy gaps generated by the logging were mapped. Seedlings of J. copaia colonised the gaps, as expected, at a higher density than in the surrounding forest. In 2006, we exhaustively sampled all saplings and adult trees available in a 25-ha area. The samples were genotyped at nine microsatel-lite loci, and the distribution of genetic diversity was inspected by analyses of spatial autocorrelation, automated Bayesian assignment and comparisons of diversity between cohorts by bootstrap (RaBoT). Results Spatial autocorrelation was found to extend farther in post-disturbance saplings than in the undisturbed population (100 m and beyond versus less than 50 m), and divergent clumps (F ST =0.05) of related genotypes were found; genetic Handling Editor: Ricardo Alia Contribution of the co-authors TL analysed data; RV collected samples and data, ran data analyses and wrote the paper; VT and SG collected and cured data; IS conceived the experiment, ran data analyses and wrote the manuscript. Thomas Leclerc tragically deceased in a car accident during his internship in French Guiana while carrying out this research. The remaining authors completed the study and wrote the manuscript on his behalf. This paper is dedicated to his memory and to his family and friends. Electronic supplementary material The online version of this article (diversity was found to be impoverished in each clump relative to the global population at about half of the loci. Conclusion Overall, our results suggest that forest disturbance has changed the patterns of distribution of genetic diversity , with potential consequences on long-term population viability
Life after disturbance (II): the intermediate disturbance hypothesis explains genetic variation in forest gaps dominated by Virola michelii Heckel (Myristicaceae)
Fine-scale genetic structure of the threatened rosewood Dalbergia nigra from the Atlantic Forest: comparing saplings versus adults and small fragment versus continuous forest
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 dbhX10 cm, 100 individuals of 1–10cmdbh, and 100 individuals of o1 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 410 cm dbh (0–40 m) size categories. Significant spatial autocorrelations were detected over larger scales (0–140 m) in o1 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 post recruitment mortality.http://deepblue.lib.umich.edu/bitstream/2027.42/83301/1/Hardesty2005.pd
Pollen flow in fragmented landscapes maintains genetic diversity following stand-replacing disturbance in a neotropical pioneer tree, Vochysia ferruginea Mart
In forests with gap disturbance regimes, pioneer tree regeneration is typically abundant following stand-replacing disturbances, whether natural or anthropogenic. Differences in pioneer tree density linked to disturbance regime can influence pollinator behaviour and impact on mating patterns and genetic diversity of pioneer populations. Such mating pattern shifts can manifest as higher selfing rates and lower pollen diversity in old growth forest populations. In secondary forest, where more closely related pollen donors occur, an increase in biparental inbreeding is a potential problem. Here, we investigate the consequences of secondary forest colonisation on the mating patterns and genetic diversity of open-pollinated progeny arrays for the long-lived, self-compatible pioneer tree, Vochysia ferruginea, at two Costa Rican sites. Five microsatellite loci were screened across adult and seed cohorts from old growth forest with lower density, secondary forest with higher density, and isolated individual trees in pasture. Progeny from both old growth and secondary forest contexts were predominantly outcrossed (tm=1.00) and experienced low levels of biparental inbreeding (tm−ts=0.00–0.04). In contrast to predictions, our results indicated that the mating patterns of V. ferruginea are relatively robust to density differences between old growth and secondary forest stands. In addition, we observed that pollen-mediated gene flow possibly maintained the genetic diversity of open-pollinated progeny arrays in stands of secondary forest adults. As part of a natural resource management strategy, we suggest that primary forest remnants should be prioritised for conservation to promote restoration of genetic diversity during forest regeneration
Informe de experiencia profesional realizado en la Municipalidad Provincial de Loreto- Nauta, periodo 2006-2009;
Trabajo de suficiencia profesionalDescribe a la Institución y su entorno económico en el cual se desarrolla. Realiza un trabajo descriptivo de la formulación de proyectos de inversión realizada en la Unidad Formuladora de la Sub gerencia de Estudios y Proyectos de la Municipalidad Provincial de Loreto- Nauta. Verifica y compara la aplicación de las técnicas empleadas para la elaboración de un proyecto de inversión de acuerdo al SNIP. Sustenta la experiencia profesional adquirida en la Unidad Formuladora de la Sub Gerencia de Estudios y Proyectos de la Municipalidad Provincial de Loreto -Nauta mediante una descripción detallada de la misma y propone alternativas para el logro de los objetivos y metas de la Municipalidad Provincial de Loreto- Nauta. Concluye que el personal no se identifica con la visión, misión y los objetivos de la institución, por cuanto su actuar está condicionado por el apoyo electoral brindado a la autoridad para su elección. Falta de concertación e integración de las instituciones del estado generando duplicidad de intervenciones e ineficiencias en el uso de los recursos entre la Sub Región Loreto-Nauta y la Municipalidad Provincial de Loreto- Nauta. La capacitación y actualización del personal, contribuye a mejorar la calidad, la capacidad y el criterio de análisis de los profesionales que elaboran y formulación de los proyectos de preinversión