Biology subjects

Linan, A. G.

Publications and source records attributed to Linan, A. G..

3 recordsLinked to original sources

bioRxiv2026

A disjunct distribution and population fragmentation shape rangewide genetic diversity and structure of the endangered Physaria globosa (Brassicaceae)

Population genetic analysis of species of conservation concern provides information to devise management plans to effectively conserve the genetic variation of endangered species. One such endangered plant, Physaria globosa is a federally endangered species in the mustard family with a geographically restricted range that occurs in four disjunct locations in Indiana, Kentucky, and Tennessee (i.e., Highland Rim and Nashville Basin regions) and along the Wabash, Kentucky, and Cumberland Rivers. In this study, we sampled populations from throughout the range of P. globosa, genotyped them using 20 microsatellite loci, and assessed genetic diversity and structure within and among populations. The goals of the study were to understand: 1) levels of genetic diversity in P. globosa and whether populations show evidence of having experienced reductions in genetic diversity as the result of genetic bottlenecks, genetic drift, or inbreeding, 2) rangewide genetic diversity and structure in P. globosa and how genetic structure is affected by the disjunctions in the species range, and 3) implications for prioritization of in-situ and ex-situ conservation efforts. On average, P. globosa showed comparable levels of genetic diversity to other species of Physaria. However, some populations showed evidence of inbreeding, genetic bottlenecks, or decreases in genetic diversity, possibly due to anthropogenic or climate-related pressures and decreases in population size due to competition with invasive bush honeysuckle. Genetic variation was strongly structured into two main geographic groups, one in the northern part of the species range (KY and IN), and the other in the southern part of the species range (TN), but some populations likely originated via long-distance dispersal. We also found significant isolation by distance, likely due to both life history characteristics and physical barriers associated with the complex topological structure of the landscape occupied by P. globosa, limiting population connectivity. Given the strong genetic structure found in P. globosa, several populations should be protected and managed within each geographic region to conserve genetic variation. Ex situ conservation will also be important to protect genetic diversity, particularly for populations that are difficult to access and manage.

genetics↗

bioRxiv2025

Digging into the general dynamic model: Island ontogeny predicts shifting micro-evolutionary processes in a Mascarene flowering plant radiation

AO_SCPLOWBSTRACTC_SCPLOWIsland studies have been integral in the development of process-oriented biodiversity models such as the general dynamic model (GDM) of oceanic island biogeography. While empirical tests of the GDM primarily come from phylogeographic studies, tests incorporating comprehensive population-level sampling of island radiations are rare. In this study, we elucidate the evolutionary processes driving the diversification of Hibiscus section Lilibiscus in the Mascarene archipelago using population-level sampling and 2bRAD sequencing. Our goals were to: 1) assess species relationships and resolve taxonomic issues; 2) test patterns of intra- and interspecific genetic differentiation under a model of shifting speciation processes as islands age; and 3) utilize demographic modeling to infer the relative divergence times of populations in the archipelago. We found the Mascarene radiation of sect. Lilibiscus to be monophyletic and confirmed the presence of six morphologically distinct species. Species richness and phylogenetic relationships supported the expectations of the GDM. Namely, we found that morphologically similar populations of the same species on the intermediate-aged island, Mauritius, diverged earlier and showed greater divergence than morphologically disparate species on the youngest Mascarene island, Reunion. These patterns are consistent with the hypothesis that ecological selection may be affecting speciation on the youngest island, drift may be the most important force on the middle-aged island. Although not tested here, given that the oldest island is in a late stage of subsidence, extinction may be the most important evolution force occurring on the oldest island, consistent with the expectation that evolutionary processes occurring across each of these islands may be influenced by ontogenetic stage. We also found evidence that some species in the group may be naturally rare, suggesting that the rarity of species may not only be from recent habitat loss. Our study is the first to use population-level data to test complex predictions of the GDM and demonstrate that the most important evolutionary processes shift depending on island ontogeny.

evolutionary biology↗

bioRxiv2020

The evolutionary assembly of forest communities along environmental gradients: recent diversification or sorting of pre-adapted clades?

O_LIBiogeographic events occurring in the deep past can contribute to the structure of modern ecological communities. However, little is known about how the emergence of environmental gradients shape the evolution of species that underlie community assembly. In this study, we address how the creation of novel environments lead to community assembly via two non-mutually exclusive processes: 1) the immigration and ecological sorting of pre-adapted clades (ISPC), and 2) recent adaptive diversification (RAD). We study these processes in the context of the elevational gradient created by the uplift of the Central Andes. C_LIO_LIWe develop a novel approach and method based on the decomposition of species turnover into within- and among-clade components, where clades correspond to lineages that originated before mountain uplift. Effects of ISPC and RAD can be inferred from how components of turnover change with elevation. We test our approach using data from over 500 Andean forest plots. C_LIO_LIWe found that species turnover between communities at different elevations is dominated by the replacement of clades that originated before the uplift of the Central Andes. C_LIO_LIOur results suggest that immigration and sorting of clades pre-adapted to montane habitats is the primary mechanism shaping communities across elevations. C_LI

ecology↗