Dataset Information

AFLP diversity and spatial structure of Calycophyllum candidissimum (Rubiaceae), a dominant tree species of Nicaragua's critically endangered seasonally dry forest.

ABSTRACT: The Central American seasonally dry tropical (SDT) forest biome is one of the worlds' most endangered ecosystems, yet little is known about the genetic consequences of its recent fragmentation. A prominent constituent of this biome is Calycophyllum candidissimum, an insect-pollinated and wind-dispersed canopy tree of high socio-economic importance, particularly in Nicaragua. Here, we surveyed amplified fragment length polymorphisms across 13 populations of this species in Nicaragua to elucidate the relative roles of contemporary vs historical factors in shaping its genetic variation. Genetic diversity was low in all investigated populations (mean HE=0.125), and negatively correlated with latitude. Overall population differentiation was moderate (?ST=0.109, P<0.001), and Bayesian analysis of population structure revealed two major latitudinal clusters (I: 'Pacific North'+'Central Highland'; II: 'Pacific South'), along with a genetic cline between I and II. Population-based cluster analyses indicated a strong pattern of 'isolation by distance' as confirmed by Mantel's test. Our results suggest that (1) the low genetic diversity of these populations reflects biogeographic/population history (colonisation from South America, Pleistocene range contractions) rather than recent human impact; whereas (2) the underlying process of their isolation by distance pattern, which is best explained by 'isolation by dispersal limitation', implies contemporary gene flow between neighbouring populations as likely facilitated by the species' efficient seed dispersal capacity. Overall, these results underscore that even tree species from highly decimated forest regions may be genetically resilient to habitat fragmentation due to species-typical dispersal characteristics, the necessity of broad-scale measures for their conservation notwithstanding.

SUBMITTER: Davila-Lara A

PROVIDER: S-EPMC5597786 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

AFLP diversity and spatial structure of Calycophyllum candidissimum (Rubiaceae), a dominant tree species of Nicaragua's critically endangered seasonally dry forest.

Dávila-Lara A A Affenzeller M M Tribsch A A Díaz V V Comes H P HP

Heredity 20170802 4

The Central American seasonally dry tropical (SDT) forest biome is one of the worlds' most endangered ecosystems, yet little is known about the genetic consequences of its recent fragmentation. A prominent constituent of this biome is Calycophyllum candidissimum, an insect-pollinated and wind-dispersed canopy tree of high socio-economic importance, particularly in Nicaragua. Here, we surveyed amplified fragment length polymorphisms across 13 populations of this species in Nicaragua to elucidate ...[more]

PMID: 28767103

Similar Datasets

Project description:Climatic change-induced water stress has been found to threaten the viability of trees, especially endangered species, through inhibiting their recruitment. Nyssa yunnanensis, a plant species with extremely small populations (PSESP), consists of only two small populations of eight mature individuals remaining in southwestern China. In order to determine the barriers to regeneration, both in situ and laboratory experiments were performed to examine the critical factors hindering seed germination and seedling establishment. The results of in situ field experiments demonstrated that soil water potentials lower than -5.40 MPa (experienced in December) had significantly inhibitory effects on seedling survival, and all seedlings perished at a soil water potential of -5.60 MPa (January). Laboratory experiments verified that N. yunnanensis seedlings could not survive at a 20% PEG 6000 concentration (-5.34 MPa) or 1/5 water-holding capacity (WHC; -5.64 MPa), and seed germination was inhibited in the field from September (-1.10 MPa) to November (-4.30 MPa). Our results suggested that soil water potentials between -5.34 and -5.64 MPa constituted the range of soil water potentials in which N. yunnanensis seedlings could not survive. In addition to water deficit, intensified autotoxicity, which is concentration-dependent, resulted in lower seed germination and seedling survival. Thus, seed establishment was probably simultaneously impacted by water deficit and aggravated autotoxicity. Meteorological records from the natural distribution areas of N. yunnanensis indicated that mean annual rainfall and relative humidity have declined by 21.7% and 6.3% respectively over past 55 years, while the temperature has increased by 6.0%. Climate change-induced drought, along with a poor resistance and adaptability to drought stress, has severely impacted the natural regeneration of N. yunnanensis. In conclusion, climate change-induced drought has been implicated as a regulating factor in the natural regeneration of N. yunnanensis through suppressing seed germination and screening out seedlings in the dry season. Based on the experimental findings, habitat restoration and microclimate improvement should both be highlighted in the conservation of this particular plant species.

Project description:Several studies have shown that rainfall seasonality, soil heterogeneity, and increased nitrogen (N) deposition may have important effects on tropical forest function. However, the effects of these environmental controls on soil microbial communities in seasonally dry tropical forests are poorly understood. In a seasonally dry tropical forest in the Yucatan Peninsula (Mexico), we investigated the influence of soil heterogeneity (which results in two different soil types, black and red soils), rainfall seasonality (in two successive seasons, wet and dry), and 3 years of repeated N enrichment on soil chemical and microbiological properties, including bacterial gene content and community structure. The soil properties varied with the soil type and the sampling season but did not respond to N enrichment. Greater organic matter content in the black soils was associated with higher microbial biomass, enzyme activities, and abundances of genes related to nitrification (amoA) and denitrification (nirK and nirS) than were observed in the red soils. Rainfall seasonality was also associated with changes in soil microbial biomass and activity levels and N gene abundances. Actinobacteria, Proteobacteria, Firmicutes, and Acidobacteria were the most abundant phyla. Differences in bacterial community composition were associated with soil type and season and were primarily detected at higher taxonomic resolution, where specific taxa drive the separation of communities between soils. We observed that soil heterogeneity and rainfall seasonality were the main correlates of soil bacterial community structure and function in this tropical forest, likely acting through their effects on soil attributes, especially those related to soil organic matter and moisture content.IMPORTANCE Understanding the response of soil microbial communities to environmental factors is important for predicting the contribution of forest ecosystems to global environmental change. Seasonally dry tropical forests are characterized by receiving less than 1,800 mm of rain per year in alternating wet and dry seasons and by high heterogeneity in plant diversity and soil chemistry. For these reasons, N deposition may affect their soils differently than those in humid tropical forests. This study documents the influence of rainfall seasonality, soil heterogeneity, and N deposition on soil chemical and microbiological properties in a seasonally dry tropical forest. Our findings suggest that soil heterogeneity and rainfall seasonality are likely the main factors controlling soil bacterial community structure and function in this tropical forest. Nitrogen enrichment was likely too low to induce significant short-term effects on soil properties, because this tropical forest is not N limited.

Project description:The extent to which interspecific niche differences structure plant communities is highly debated, with extreme viewpoints ranging from fine-scaled niche partitioning, where every species in the community is specialized to a distinct niche, to neutrality, where species have no niche or fitness differences. However, there exists a default position wherein niches of species in a community are determined by their evolutionary and biogeographic histories, irrespective of other species within the community. According to this viewpoint, a broad range of pair-wise niche overlaps-from completely overlapping to completely distinct-are expected in any community without the need to invoke interspecific interactions. We develop a method that can test for both habitat associations and niche differences along an arbitrary number of spatial and temporal niche dimensions and apply it to a 24-yr data set of the eight dominant woody-plant species (representing 84% and 76% of total community abundance and basal area, respectively) from a 50-ha permanent plot in a southern Indian tropical dry forest, using edaphic, topographic, and precipitation variables as niche axes. Species separated into two broad groups in niche space-one consisting of three canopy species and the other of a canopy species and four understory species-along axes that corresponded mainly to variation in soil P, Al and a topographic index of wetness. Species within groups tended to have significantly greater niche overlap than expected by chance. Community-wide niche overlap in spatial and temporal niche axes was never smaller than expected by chance. Species-habitat associations were neither necessary nor sufficient preconditions for niche differences to be present. Our results suggest that this tropical dry-forest community consists of several tree species with broadly overlapping niches, and where significant niche differences do exist, they are not readily interpretable as evidence for niche differentiation. We argue, based on a survey of the literature, that many of the observed niche differences in tropical forests are more parsimoniously viewed as autecological differences between species that exist independently of interspecific interactions.

Project description:Haemosporidian parasites of the genera Plasmodium and Haemoproteus can have detrimental effects on individual birds and populations. Despite recent investigations into the distribution and richness of these parasites and their vertebrate hosts, little is known about their dipteran vectors. The Neotropics has the highest diversity of mosquitoes in the world, but few studies have tried to identify vectors in this area, hampering the understanding of the ecology of avian malaria in the highly diverse Neotropical environments.Shannon traps and active collection were used to capture 27,110 mosquitoes in a Seasonally Dry Tropical Forest in southeastern Brazil, a highly endangered ecosystem.We screened 17,619 mosquito abdomens from 12 different species and several unidentified specimens of Culex, grouped into 1,913 pools, for the presence of haemosporidians. Two pools (out of 459) of the mosquito Mansonia titillans and one pool (out of 29) of Mansonia pseudotitillans were positive for Plasmodium parasites, with the detection of a new parasite lineage in the former species. Detected Plasmodium lineages were distributed in three different clades within the phylogenetic tree revealing that Mansonia mosquitoes are potential vectors of genetically distant parasites. Two pools of Culex spp. (out of 43) were positive for Plasmodium gallinaceum and closely related lineages. We found a higher abundance of these putative vectors in pasture areas, but they were also distributed in areas at intermediate and late successional stages. One pool of the mosquito Psorophora discrucians (out of 173) was positive for Haemoproteus.The occurrence of different Plasmodium lineages in Mansonia mosquitoes indicates that this genus encompasses potential vectors of avian malaria parasites in Brazil, even though we did not find positive thoraces among the samples tested. Additional evidence is required to assign the role of Mansonia mosquitoes in avian malaria transmission and further studies will add information about evolutionary and ecological aspects of avian haemosporidia and untangle the diversity of their vectors in Brazil.

Dataset Information

AFLP diversity and spatial structure of Calycophyllum candidissimum (Rubiaceae), a dominant tree species of Nicaragua's critically endangered seasonally dry forest.

Publications

AFLP diversity and spatial structure of Calycophyllum candidissimum (Rubiaceae), a dominant tree species of Nicaragua's critically endangered seasonally dry forest.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets