Limits to reproduction and seed size-number trade-offs that shape forest dominance and future recovery.

The relationships that control seed production in trees are fundamental to understanding the evolution of forest species and their capacity to recover from increasing losses to drought, fire, and harvest. A synthesis of fecundity data from 714 species worldwide allowed us to examine hypotheses that are central to quantifying reproduction, a foundation for assessing fitness in forest trees. Four major findings emerged.

Revisiting the comparative phylogeography of unglaciated eastern North America: 15 years of patterns and progress.

In a landmark comparative phylogeographic study, "Comparative phylogeography of unglaciated eastern North America," Soltis et al. (, 2006, 15, 4261) identified geographic discontinuities in genetic variation shared across taxa occupying unglaciated eastern North America and proposed several common biogeographical discontinuities related to past climate fluctuations and geographic barriers. Since 2006, researchers have published many phylogeographical studies and achieved many advances in genotyping and analytical techniques; however, it is unknown how this work has changed our understanding of the factors shaping the phylogeography of eastern North American taxa.

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.

Understanding how an amphicarpic species with a mixed mating system responds to fire: a population genetic approach.

Amphicarpic plants produce both above-ground and below-ground seeds. Because below-ground seeds are protected in the soil and may maintain viability when above-ground conditions are stressful, they were proposed as an adaptation to recolonize a site after disturbance. However, whether below-ground seeds are the main colonizers after a disturbance remains unknown.

The role of genus and life span in predicting seed and vegetative trait variation and correlation in Lathyrus, Phaseolus, and Vicia.

Premise: Annual and perennial life history transitions are abundant among angiosperms, and understanding the phenotypic variation underlying life span shifts is a key endeavor of plant evolutionary biology. Comparative analyses of trait variation and correlation networks among annual and perennial plants is increasingly important as new herbaceous perennial crops are being developed for edible seed. However, it remains unclear how seed to vegetative growth trait relationships correlate with life span.

Is there tree senescence? The fecundity evidence.

Despite its importance for forest regeneration, food webs, and human economies, changes in tree fecundity with tree size and age remain largely unknown. The allometric increase with tree diameter assumed in ecological models would substantially overestimate seed contributions from large trees if fecundity eventually declines with size. Current estimates are dominated by overrepresentation of small trees in regression models.

A reassessment of testate amoebae diversity in Tierra del Fuego peatlands: Implications for large scale inferences.

Testate amoebae are a diverse group of shelled protists frequently used as model organisms in microbial biogeography. Relatively few species have been reported for the Southern Hemisphere, however, it remains unclear whether this lower diversity is real or an artifact of under-sampling or misidentifications, which would reduce their potential to address macroecological questions. We evaluated testate amoebae diversity from the full range of habitats occurring within two Tierra del Fuego peatlands and compared it with the reported diversity for the area and from the Northern Hemisphere peatlands.

The phylogeographic history of a range disjunction in eastern North America: the role of post-glacial expansion into newly suitable habitat.

Premise: A disjunct distribution, where a species' geographic range is discontinuous, can occur through vicariance or long-distance dispersal. Approximately 75 North American plant species exhibit a ~650 km disjunction between the Ozark and Appalachian regions. This disjunction is attributed to biogeographic forces including: (1) Eocene-Oligocene vicariance by the formation of the Mississippi embayment; (2) Pleistocene vicariance from interglacial flooding; (3) post-Pleistocene northward colonization from separate glacial refugia; (4) Hypsithermal vicariance due to climate fluctuations; and (5) recent long-distance dispersal.

Improving species status assessments under the U.S. Endangered Species Act and implications for multispecies conservation challenges worldwide.

Despite its successes, the U.S. Endangered Species Act (ESA) has proven challenging to implement due to funding limitations, workload backlog, and other problems.

Next-generation field courses: Integrating Open Science and online learning.

As Open Science practices become more commonplace, there is a need for the next generation of scientists to be well versed in these aspects of scientific research. Yet, many training opportunities for early career researchers (ECRs) could better emphasize or integrate Open Science elements. Field courses provide opportunities for ECRs to apply theoretical knowledge, practice new methodological approaches, and gain an appreciation for the challenges of real-life research, and could provide an excellent platform for integrating training in Open Science practices.

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.

Ecological Dynamics: Integrating Empirical, Statistical, and Analytical Methods.

Understanding ecological processes and predicting long-term dynamics are ongoing challenges in ecology. To address these challenges, we suggest an approach combining mathematical analyses and Bayesian hierarchical statistical modeling with diverse data sources. Novel mathematical analysis of ecological dynamics permits a process-based understanding of conditions under which systems approach equilibrium, experience large oscillations, or persist in transient states.

Planting position and shade enhance native seedling performance in forest restoration for an endangered malagasy plant.

The critically endangered tree is confined to a few diminished and degraded forest fragments on the Malagasy highlands. This habitat is vulnerable to loss due to frequent fires in the surrounding grassland that threaten to spread into the forest. One of these fragments is the focus a conservation project and here the managers aim to conserve by restoring its forest habitat to its former extent as evidenced by remnant woody plants.