Publication Search Results

ID: 154061
Type: article
Authors: Bell‐Doyon, Philip; Laroche, Jérôme; Saltonstall, Kristin; Villareal Aguilar, Juan Carlos
Keywords: STRI
Abstract: Epiphytes face several constraints regarding nutrient acquisition: They are disconnected from soil minerals and they have to mainly rely on nutrients leached by precipitation and microbes. The cycad, Zamia pseudoparasitica Yates, is the only known strictly epiphytic gymnosperm, and it is endemic to Panamanian rainforests. Cycads have evolved specialized coralloid roots that host endophytic cyanobacteria specialized in nitrogen fixation. We collected coralloid roots from plants in the Omar Torrijos National Park, Provincia de Coclé. DNA was extracted from fresh inner coralloid roots, and the bacteriome was described using two molecular markers: rbcL-rbcX (targeting cyanobacteria) and 16S (all bacteria). Sixteen samples were sequenced for rbcL-rbcX yielding sequences belonging to a monophyletic group within the order Nostocales. One hundred and sixty-five amplicon sequence variants (ASVs) were found in at least two of our 27 samples amplified for 16S. Nostocales, Rhizobiales, and Acetobacterales were the three most diverse and abundant orders of bacteria found within the coralloid roots, and the candidate phylum WPS-2 was also found in many samples. We performed a de novo assembly from a single culture of the endophytic cyanobacteria. A phylogenomic analysis of the isolate places the cyanobacterium in a sister clade to mostly symbiotic taxa from mosses, liverworts, and lichens. Additionally, the isolate has genes putatively involved in symbiotic signaling, hormogonium differentiation, ammonium transport, nitrogen fixation, heterocyst differentiation, sulfate transport, and secondary metabolites. Although dominated by organisms with the capacity to fix nitrogen, coralloid roots are also inhabited by a diverse community of other taxa which may also play biologically important roles.

ID: 156941
Type: article
Authors: Castillo, Anakena M.; Saltonstall, Kristin; Arias, Carlos F.; Chavarria, Karina A.; Ramírez-Camejo, Luis A.; Mejía, Luis C.; De León, Luis F.
Keywords: STRI
Abstract: Insects host a highly diverse microbiome, which plays a crucial role in insect life. However, the composition and diversity of microbiomes associated with Neotropical freshwater insects is virtually unknown. In addition, the extent to which diversification of this microbiome is associated with host phylogenetic divergence remains to be determined. Here, we present the first comprehensive analysis of bacterial communities associated with six closely related species of Neotropical water striders in Panama. We used comparative phylogenetic analyses to assess associations between dominant bacterial linages and phylogenetic divergence among species of water striders. We found a total of 806 16S rRNA amplicon sequence variants (ASVs), with dominant bacterial taxa belonging to the phyla Proteobacteria (76.87%) and Tenericutes (19.51%). Members of the α- (e.g., Wolbachia) and γ- (e.g., Acinetobacter, Serratia) Proteobacteria, and Mollicutes (e.g., Spiroplasma) were predominantly shared across species, suggesting the presence of a core microbiome in water striders. However, some bacterial lineages (e.g., Fructobacillus, Fluviicola and Chryseobacterium) were uniquely associated with different water strider species, likely representing a distinctive feature of each species' microbiome. These findings indicate that both host identity and environmental context are important drivers of microbiome diversity in water striders. In addition, they suggest that diversification of the microbiome is associated with diversification in water striders. Although more research is needed to establish the evolutionary consequences of host-microbiome interaction in water striders, our findings support recent work highlighting the role of bacterial community host-microbiome codiversification.

ID: 152577
Type: article
Authors: Bennett, Kelly L.; Almanza, Alejandro; McMillan, W. O.; Saltonstall, Kristin; Vdovenko, Evangelina López; Vinda, Jorge S.; Mejía, Luis; Driesse, Kaitlin; León, Luis F. De; Loaiza, José R.
Keywords: STRI
Abstract: The microbiome plays a key role in the biology, ecology and evolution of arthropod vectors of human pathogens. Vector-bacterial interactions could alter disease transmission dynamics through modulating pathogen replication and/or vector fitness. Nonetheless, our understanding of the factors shaping the bacterial community in arthropod vectors is incomplete. Using large-scale 16S amplicon sequencing, we examine how habitat disturbance structures the bacterial assemblages of field-collected whole-body hematophagous arthropods that vector human pathogens including mosquitoes (Culicidae), sand flies (Psychodidae), biting midges (Ceratopogonidae) and hard ticks (Ixodidae). We found that all comparisons of the bacterial community among species yielded statistically significant differences, but a difference was not observed between adults and nymphs of the hard tick, Haemaphysalis juxtakochi. While Culicoides species had the most distinct bacterial community among dipterans, tick species were composed of entirely different bacterial OTU’s. We observed differences in the proportions of some bacterial types between pristine and disturbed habitats for Coquillettidia mosquitoes, Culex mosquitoes, and Lutzomyia sand flies, but their associations differed within and among arthropod assemblages. In contrast, habitat quality was a poor predictor of differences in bacterial classes for Culicoides biting midges and hard tick species. In general, similarities in the bacterial communities among hematophagous arthropods could be explained by their phylogenetic relatedness, although intraspecific variation seems influenced by habitat disturbance.

ID: 152248
Type: article
Authors: Bennett, Kelly L.; Gómez-Martínez, Carmelo; Chin, Yamileth; Saltonstall, Kristin; McMillan, W. Owen; Rovira, José R.; Loaiza, José R.
Keywords: STRI
Abstract: Aedes aegypti and Aedes albopictus develop in the same aquatic sites where they encounter microorganisms that influence their life history and capacity to transmit human arboviruses. Some bacteria such as Wolbachia are currently being considered for the control of Dengue, Chikungunya and Zika. Yet little is known about the dynamics and diversity of Aedes-associated bacteria, including larval habitat features that shape their tempo-spatial distribution. We applied large-scale 16S rRNA amplicon sequencing to 960 adults and larvae of both Ae. aegypti and Ae. albopictus mosquitoes from 59 sampling sites widely distributed across nine provinces of Panama. We find both species share a limited, yet highly variable core microbiota, reflecting high stochasticity within their oviposition habitats. Despite sharing a large proportion of microbiota, Ae. aegypti harbours higher bacterial diversity than Ae. albopictus, primarily due to rarer bacterial groups at the larval stage. We find significant differences between the bacterial communities of larvae and adult mosquitoes, and among samples from metal and ceramic containers. However, we find little support for geography, water temperature and pH as predictors of bacterial associates. We report a low incidence of natural Wolbachia infection for both Aedes and its geographical distribution. This baseline information provides a foundation for studies on the functions and interactions of Aedes-associated bacteria with consequences for bio-control within Panama.

ID: 152061
Type: article
Authors: González, Cely T.; Saltonstall, Kristin; Fernández-Marin, Hermogenes
Keywords: STRI

ID: 152258
Type: article
Authors: Hall, Jefferson S.; Harris, David J.; Saltonstall, Kristin; Medjibe, Vincent de Paul; Ashton, Mark S.; Turner, Benjamin L.
Keywords: STRI
Abstract: 1.Tropical forests are hyperdiverse, yet extensive areas of monodominant forest occur in the tropics worldwide. Most long-lived and persistent monodominant tree species form ectomycorrhizal fungi symbioses, allowing them to obtain nutrients directly from soil organic matter. This might promote monodominance by reducing nutrient availability to co-occurring species, the majority of which form associations with arbuscular mycorrhizal fungi. 2.Gilbertiodendron dewevrei forest is the most widespread monodominant forest in tropical Africa. Its distribution appears determined in part by moisture availability, but its monodominance is not thought to be driven by its fungal partner or soil fertility. 3.Here we compare soil fertility of twenty G. dewevrei stands to mixed forest from three sites across an 8,400 km2 region of the Central African Republic and the Republic of Congo. In contrast to previous studies, we find monodominant G. dewevrei stands associated with infertile soils, as base cations (calcium, magnesium, total exchangeable bases) and extractable manganese are extremely low, and significantly lower in soils under G. dewevrei forest compared to mixed forest. Further, and consistent with ectomycorrhizal forests globally, soil carbon to nitrogen and carbon to phosphorus ratios are significantly higher in G. dewevrei stands than in mixed forest stands, providing evidence in support of direct acquisition of nitrogen and phosphorus from soil organic matter by ectomycorrhizal fungi. 4.Gilbertiodendron dewevrei recruits from the seedling bank, with its large seedlings surviving in high densities for over a decade. We tested whether light plasticity could facilitate monodominance by growing seedlings of G. dewevrei under controlled light conditions. We found that its seedlings grow well under a wide range of irradiance levels and conclude that this plasticity affords a competitive advantage. 5.Synthesis: We reframe the discussion of factors contributing to monodominance of G. dewevrei into one of resource acquisition and use efficiency. In particular, G. dewevrei is associated with moist and infertile soils and competes well under a variety of light conditions. Our data is consistent with a model where root associations with ectomycorrhizal fungi drive monodominance through the direct acquisition of nutrients from soil organic matter, promoting nutrient limitation of co-occurring species.

ID: 150619
Type: article
Authors: Kelehear, Crystal; Saltonstall, Kristin; Torchin, Mark E.
Keywords: STRI
Abstract: Pathogens are increasingly implicated in amphibian declines but less is known about parasites and the role they play. We focused on a genus of nematodes (Rhabdias) that is widespread in amphibians and examined their genetic diversity, abundance (prevalence and intensity), and impact in a common toad (Rhinella horribilis) in Panama. Our molecular data show that toads were infected by at least four lineages of Rhabdias, most likely Rhabdias pseudosphaerocephala, and multiple lineages were present in the same geographic locality, the same host and even the same lung. Mean prevalence of infection per site was 63% and mean intensity of infection was 31 worms. There was a significant effect of host size on infection status in the wild: larger toads were more likely to be infected than were smaller conspecifics. Our experimental infections showed that toadlets that were penetrated by many infective Rhabdias larvae grew less than those who were penetrated by few larvae. Exposure to Rhabdias reduced toadlet locomotor performance (both sustained speed and endurance) but did not influence toadlet survival. The effects of Rhabdias infection on their host appear to be primarily sublethal, however, dose-dependent reduction in growth and an overall impaired locomotor performance still represents a significant reduction in host fitness.

ID: 153264
Type: article
Authors: Mighell, Kimberly; Saltonstall, Kristin; Turner, Benjamin L.; Espinosa‐Tasón, Jaime; Bael, Sunshine A. Van
Keywords: STRI
Abstract: While the endosymbiotic communities recruited by plants are known to vary among host species and across environmental gradients, the drivers of community assembly remain poorly understood. We tested the hypothesis that establishment of an endosymbiotic bacterial community is driven primarily by the influence of the abiotic environment on biotic interactions between plant and soil bacteria. We planted sterile Jatropha curcas seedlings at three field sites in Panama and in a greenhouse with soil from those sites. After allowing sufficient time for endosymbiont colonization, we sequenced bacterial 16S rRNA to study the endophytic bacterial community in root and leaf tissue. We compared the communities between field and greenhouse plants and examined associations among the endosymbionts, the soil microbial community, and local abiotic factors. We found that endosymbiont richness and community composition varied between the greenhouse and field, despite plants being grown in the same soil. Plants in each field site harbored a distinct bacterial community, determined by soil microbes and select environmental variables, particularly major plant nutrients. Jatropha curcas can harbor a wide variety of endosymbiotic communities, and the composition of these communities is a product of the local environment. Fertility and agricultural practices may determine the fate of plant symbionts and therefore plant properties modulated through those symbionts.

ID: 150242
Type: article
Authors: Williams, Jared; Lambert, Adam M.; Long, Randy; Saltonstall, Kristin
Keywords: STRI
Abstract: Premise of the Study Hybridization between previously isolated species or lineages can stimulate invasiveness because of increased genetic diversity and inherited traits facilitating competitive and reproductive potential. We evaluated differences in stand characteristics and sexual and vegetative reproduction among native, introduced, and hybrid Phragmites australis lineages in the southwestern United States. We also assessed the degree of hybridization among lineages and backcrossing of hybrids with parental lineages. Methods Growth and morphological characteristics were measured in native, introduced, and hybrid Phragmites stands to evaluate relative cover and dominance in associated plant communities. Panicles were collected from stands to evaluate germination, dormancy, and differences in seed traits. Seedlings from germination trials were genotyped to determine frequency of crossing and backcrossing among lineages. Key Results Introduced and hybrid Phragmites stands had significantly greater stem and panicle densities than native stands and were more likely to be dominant members of their respective plant communities. Hybrid seed outputs were significantly greater, but hybrid seeds had lower germination rates than those from native and introduced lineages. We detected a novel hybridization event between native and introduced lineages, but found no strong evidence of hybrids backcrossing with parental lineages. Conclusions Hybrid Phragmites in the Southwest exhibits reproductive, genetic, and morphological characteristics from both parental lineages that facilitate dispersal, establishment, and aggressive growth, including high reproductive output, rhizome viability, and aboveground biomass, with smaller seeds and greater genetic diversity than its progenitors. Our results show hybrids can inherit traits that confer invasiveness and provide insight for managing this species complex and other cryptic species with native and introduced variants with potential for intraspecific hybridization.

ID: 150138
Type: article
Authors: Turner, Benjamin L.; Zemunik, Graham; Laliberté, Etienne; Drake, Jeremy J.; Jones, F. A.; Saltonstall, Kristin
Keywords: STRI
Abstract: Long-term ecosystem development involves changes in plant community composition and diversity associated with pedogenesis and nutrient availability, but comparable changes in soil microbial communities remain poorly understood. In particular, it is unclear whether the diversity of plants and microbes respond to similar abiotic drivers, or become decoupled as resources change over long time-scales. We characterized communities of archaea, bacteria and fungi in soils along a 2-million-year chronosequence of coastal dunes in a biodiversity hot spot in Western Australia. The chronosequence involves marked changes in soil pH and nutrient availability that drive major shifts in plant community composition and diversity as soils age. Patterns of α-diversity for microbial groups differed along the chronosequence. Bacterial α-diversity was greatest in intermediate-aged soils; archaeal diversity was greater in young alkaline or intermediate-aged soils, while fungal α-diversity-like plant diversity-was greatest in old, strongly weathered soils where phosphorus is the limiting nutrient. Changes in microbial community composition along the chronosequence were explained primarily by the long-term decline in soil pH, with a smaller influence of the relative abundance of plant nutrient-acquisition strategies. However, changes between the prokaryote and fungal communities, and between fungal and plant communities, became increasingly decoupled along the chronosequence, demonstrating that the coordination of change in biological communities by abiotic drivers becomes weaker during long-term ecosystem development. Several bacterial taxa, including DA101 (Verrucomicrobia), "Candidatus Solibacter" (Acidobacteria) and Gaiella (Actinobacteria), were particularly abundant on the oldest dunes, indicating that they are adapted to acquire phosphorus from extremely infertile soils. However, we cannot disentangle the influence of phosphorus from the long-term decline in soil pH along the chronosequence. Synthesis. These results provide evidence for contrasting patterns of plant and microbial community composition and α-diversity in response to acidification and nutrient depletion during long-term pedogenesis.

ID: 143474
Type: article
Authors: Rodgers, Torrey W.; Xu, Charles C. Y.; Giacalone, Jacalyn; Kapheim, Karen M.; Saltonstall, Kristin; Vargas, Marta; Yu, Douglas W.; Somervuo, Panu; McMillan, W. O.; Jansen, Patrick A.
Keywords: STRI
Abstract: Metabarcoding of vertebrate DNA derived from carrion flies has been proposed as a promising tool for biodiversity monitoring. To evaluate its efficacy, we conducted metabarcoding surveys of carrion flies on Barro Colorado Island (BCI), Panama, which has a well-known mammal community, and compared our results against diurnal transect counts and camera-trapping. We collected 1084 flies in 29 sampling days, conducted metabarcoding with mammal-specific (16S) and vertebrate-specific (12S) primers, and sequenced amplicons on Illumina MiSeq. For taxonomic assignment, we compared BLAST with the new program PROTAX, and we found that PROTAX improved species identifications. We detected 20 mammal, four bird, and one lizard species from carrion fly metabarcoding, all but one of which are known from BCI. Fly metabarcoding detected more mammal species than concurrent transect counts (29 sampling days, 13 species) and concurrent camera-trapping (84 sampling days, 17 species), and detected 67% of the number of mammal species documented by eight years of transect counts and camera-trapping combined, although fly metabarcoding missed several abundant species. This study demonstrates that carrion fly metabarcoding is a powerful tool for mammal biodiversity surveys, and has the potential to detect a broader range of species than more commonly used methods. This article is protected by copyright. All rights reserved.

ID: 140443
Type: article
Authors: Aiello, Annette; Saltonstall, Kristin; Young, Victor
Keywords: STRI

ID: 140281
Type: article
Authors: Guevara, Elaine E.; Veilleux, Carrie C.; Saltonstall, Kristin; Caccone, Adalgisa; Mundy, Nicholas I.; Bradley, Brenda J.
Keywords: STRI
Abstract: Objectives We explored whether variation in the sweet taste receptor protein T1R3 in primates could contribute to differences in sweet taste repertoire among species, potentially reflecting coevolution with local plants. Specifically, we examined which primates are likely to be sweet "tasters" of brazzein, a protein found in the fruit of the African plant Pentadiplandra brazzeana that tastes intensely sweet to humans, but provides little energy. Sweet proteins like brazzein are thought to mimic the taste of sugars to entice seed dispersers. We examined the evolution of T1R3 and assessed whether primates are likely "deceived" by such biochemical mimicry. Methods Using published and new sequence data for TAS1R3, we characterized 57 primates and other mammals at the two amino acid sites necessary to taste brazzein to determine which species are tasters. We further used dN/dS-based methods to look for statistical evidence of accelerated evolution in this protein across primate lineages. Results The taster genotype is shared across most catarrhines, suggesting that most African primates can be "tricked" into eating and dispersing P. brazzeana's seeds for little caloric gain. Western gorillas (Gorilla gorilla), however, exhibit derived mutations at the two brazzein-critical positions, and although fruit is a substantial portion of the western gorilla diet, they have not been observed to eat P. brazzeana. Our analyses of protein evolution found no signature of positive selection on TAS1R3 along the gorilla lineage. Discussion We propose that the gorilla-specific mutations at the TAS1R3 locus encoding T1R3 could be a counter-adaptation to the false sweet signal of brazzein.

ID: 140442
Type: article
Authors: Lambert, Adam M.; Saltonstall, Kristin; Long, Randy; Dudley, Tom L.
Keywords: STRI

ID: 140444
Type: article
Authors: Saltonstall, Kristin
Keywords: STRI

ID: 139713
Type: article
Authors: Saltonstall, Kristin; Lambert, Adam M.; Rice, Nick
Keywords: STRI

ID: 140095
Type: article
Authors: Saltonstall, Kristin; Meyerson, Laura A.
Keywords: STRI

ID: 133368
Type: article
Authors: Sellers, Andrew J.; Saltonstall, Kristin; Davidson, Timothy M.
Keywords: STRI; si-federal; fellow

ID: 118635
Type: article
Authors: Bonnett, Graham D.; Kushner, Josef N. S.; Saltonstall, Kristin
Keywords: STRI; si-federal

ID: 127497
Type: article
Authors: Hardion, Laurent; Verlaque, Regine; Saltonstall, Kristin; Leriche, Agathe; Vila, Bruno
Keywords: si-federal; STRI