Capturing and managing genetic diversity in ex situ collections of threatened tropical trees: A case study in .

Premise: Although ex situ collections of threatened plants are most useful when they contain maximal genetic variation, the conservation and maintenance of genetic diversity in collections are often poorly known. We present a case study using population genomic analyses of an ex situ collection of , a critically endangered tropical tree from Tanzania. Only ~43 individuals are known in two wild populations, and ex situ collections containing 34 individuals were established in two sites from wild-collected seed.

Divergent ecological selection maintains species boundaries despite gene flow in a rare endemic tree, Quercus acerifolia (maple-leaf oak).

Strong gene flow from outcrossing relatives tends to blur species boundaries, while divergent ecological selection can counteract gene flow. To better understand how these two forces affect the maintenance of species boundaries, we focused on a species complex including a rare species, maple-leaf oak (Quercus acerifolia), which is found in only four disjunct ridges in Arkansas. Its limited range and geographic proximity to co-occurring close relatives create the possibility for genetic swamping.

Attenuation of photosynthesis in nanosilver-treated is inherently linked to the particulate nature of silver.

Silver nanoparticles (AgNPs) are known to affect the physiology and morphology of plants in various ways, but the exact mechanism by which they interact with plant cells remains to be elucidated. An unresolved question of silver nanotoxicology is whether the interaction is triggered by the physical features of the particles, or by silver ions leached from their surface. In this study, we germinated and grew seedlings in synthetic medium supplemented with sub-morbid concentrations (4 μg/mL) of AgNPs and silver nitrate (AgNO).

Interspecific Hybridization and Island Colonization History, not Rarity, Most Strongly Affect the Genetic Diversity in Diospyros a Clade of Mascarene-Endemic Trees.

Many factors shape the genetic diversity of island-endemic trees, with important implications for conservation. Oceanic island-endemic lineages undergo an initial founding bottleneck during the colonization process and subsequently accumulate diversity following colonization. Moreover, many island endemics occur in small populations and are further threatened by anthropogenic factors that cause population declines, making them susceptible to losses in genetic diversity through genetic drift, inbreeding, and bottlenecks.

The evolutionary history of vines in a neotropical biodiversity hotspot: Phylogenomics and biogeography of a large passion flower clade (Passiflora section Decaloba).

Because of their extraordinary flower and leaf morphology, passion flowers (Passifloraceae) have fascinated naturalists since their discovery. Within the large, diverse (600 species) genus Passiflora is an especially enigmatic and species-rich (120 spp.) subclade, Section Decaloba, which occurs in the Neotropics and has its center of diversity in Andean montane forests.

Conservation genetics of the threatened plant species Physaria filiformis (Missouri bladderpod) reveals strong genetic structure and a possible cryptic species.

Understanding genetic diversity and structure in a rare species is critical for prioritizing both in situ and ex situ conservation efforts. One such rare species is Physaria filiformis (Brassicaceae), a threatened, winter annual plant species. The species has a naturally fragmented distribution, occupying three different soil types spread across four disjunct geographical locations in Missouri and Arkansas.

RAD-sequencing reveals patterns of diversification and hybridization, and the accumulation of reproductive isolation in a clade of partially sympatric, tropical island trees.

A common pattern observed in temperate tree clades is that species are often morphologically distinct and partially interfertile but maintain species cohesion despite ongoing hybridization where ranges overlap. Although closely related species commonly occur in sympatry in tropical ecosystems, little is known about patterns of hybridization within a clade over time, and the implications of this hybridization for the maintenance of species boundaries. In this study, we focused on a clade of sympatric trees in the genus Diospyros in the Mascarene islands and investigated whether species are genetically distinct, whether they hybridize, and how patterns of hybridization are related to the time since divergence among species.

Carbon Nanomaterials Alter Global Gene Expression Profiles.

Carbon nanomaterials (CNMs), which include carbon nanotubes (CNTs) and their derivatives, have diverse technological and biomedical applications. The potential toxicity of CNMs to cells and tissues has become an important emerging question in nanotechnology. To assess the toxicity of CNTs and fullerenol C60(OH)24, we in the present work used the budding yeast Saccharomyces cerevisiae, one of the simplest eukaryotic organisms that share fundamental aspects of eukaryotic cell biology.