Search

Premise: Globally, barriers triggered by climatic changes have caused habitat fragmentation and population allopatric divergence. Across North America, oscillations during the Quaternary have played important roles in the distribution of wildlife. Notably, diverse plant species from the Baja California Peninsula in western North America, isolated during the Pleistocene glacial–interglacial cycles, exhibit strong genetic structure and highly concordant divergent lineages across their ranges. A representative plant genus of the peninsula is Yucca, with Y. valida having the widest range. Although a dominant species, it has an extensive distribution discontinuity between 26° N and 27° N, suggesting restricted gene flow. Moreover, historical distribution models indicate the absence of an area with suitable conditions for the species during the Last Interglacial, making it an interesting model for studying genetic divergence. Methods: We assembled 4411 SNPs from 147 plants of Y. valida throughout its range to examine its phylogeography to identify the number of genetic lineages, quantify their genetic differentiation, reconstruct their demographic history and estimate the age of the species. Results: Three allopatric lineages were identified based on the SNPs. Our analyses support that genetic drift is the driver of genetic differentiation among these lineages. We estimated an age of less than 1 million years for the common ancestor of Y. valida and its sister species. Conclusions: Habitat fragmentation caused by climatic changes, low dispersal, and an extensive geographical range gap acted as cumulative mechanisms leading to allopatric divergence in Y. valida. [ABSTRACT FROM AUTHOR]

A critical knowledge gap in freshwater plant research is the lack of genetic tools necessary to answer fundamental questions about their demographic histories, adaptation and phylogenetic relationships. One example of this is Typha, a global genus of freshwater plants foundational to wetlands that also is becoming an increasingly problematic biological invader in numerous regions worldwide; although important insights have been discovered for this genus, existing markers are insufficient to answer fundamental questions about their demographic histories, adaptation and phylogenetic relationships; to identify introduced and hybrid lineages; and to examine patterns of hybridisation and introgression.We optimised a library preparation and data processing protocol to develop genome–wide nuclear and plastid resources for studying the evolutionary history, genetic structure and diversity, hybridisation, local adaptation, invasiveness, and geographical expansion dynamics of Typha.We sequenced 140 Typha samples and identified ~120 K nuclear single nucleotide polymorphisms (SNPs) that differentiate T. angustifolia, T. domingensis and T. latifolia, and retrieved their plastome sequences. We observed genetic introgression among the three species.Following a fast, straightforward and cost‐efficient genomic library preparation protocol, we produced a suite of genome‐wide resources to facilitate investigations into the taxonomy and population genetics of Typha and to advance the genomic understanding of wetland plants.The protocol described, the updated chromosome‐level genome assembly of T. latifolia, the catalogue of species‐specific SNPs, and the chloroplast sequences produced in this study comprise permanent resources that can be applied to study the genetic composition of multiple populations and hybrid zones, and will be incorporated into future studies of Typha, an ecologically important and globally invasive macrophyte. [ABSTRACT FROM AUTHOR]

A widespread Typha (cattail) hybrid zone in southeastern Canada and northeastern USA comprises T. latifolia, T. angustifolia, and their hybrid T. × glauca. In this region the hybrid is considered invasive because of its detrimental impacts on wetlands and biodiversity. Researchers and managers are increasingly interested in tracking and controlling the spread of the invasive hybrid, but this can be hampered by challenges in differentiating taxa: while the parent species and F1 hybrids can often be identified from morphological characteristics, advanced-generation and backcrossed hybrids can be common, and these have obscured morphological distinctions among taxa. Here we present five species-specific genetic markers that differentiate T. latifolia, T. angustifolia, F 1 hybrids, and advanced-generation/backcrossed hybrids. Unlike the pre-existing species-specific microsatellite markers, these markers require only PCR or PCR followed by a restriction enzyme digest, and can be visualized on an agarose gel. As a result, they require less specialized equipment than existing species-specific markers, and should therefore be useful for a larger group of practitioners. Future use of these markers could include monitoring range expansions, assessing the outcomes of restoration programs, and avoiding the unnecessary elimination of native Typha. [ABSTRACT FROM AUTHOR]

Background: Rapidly progressive dementia (RPD) is a syndrome caused by different disease entities. Accurate diagnosis is crucial as numerous proportions of these diseases are highly treatable. There are few RPD series published in South America. Knowing regional data may be useful to establish specific diagnostic guidelines based on local information. The main study objectives are to describe the etiological diagnosis of patients with RPD in Argentina and to compare the clinical characteristics and data obtained from complementary studies among patients with Autoimmune Encephalitis (AE), Prion Diseases (PD), Neurodegenerative Diseases (ND) and Other Causes (OC). Method: A multicenter observational cross‐sectional study was performed with the information obtained from patients referred to the neurology department of the participant centers. Patients with RPD criteria (developing dementia in less than 24 months) were retrospectively included between Dec‐2001 and Jun‐2019. Based on International diagnostic criteria, patients were divided into: AE, PD, ND and OC. We compared baseline clinical data, complementary exams, MRI and serologic characteristics between groups. Parametric or non‐parametric statistic and multivariate analysis was used according to the sample distribution of the available data. Result: On a sample of 328 patients with a diagnosis of RPD, 54.87% were men (n=180) with a mean age of 60.78±5.57 years at admission. The diagnosis time for dementia was 4.06 (0.83–23.6) months. The three most frequent causes were AE 23.17% (n=76), ND 22.86% (n=75) and PD 15.85% (n = 52). In 15.85% of the patients the diagnosis remained unknown. When comparing AE, ND, PD and OC, statistically significant differences were observed in age (younger age for AE, p=0.0001), higher mortality for PD (p=0.0001) and larger time of evolution in ND (p=0.0001). In the PD group more behavioral symptoms (p = 0.002) and pathological electroencephalogram (p=0.001) were found. Conclusion: In accordance with similar series, autoimmune etiology was the more frequent cause. This is the first South American RPD multicentric study. These results might supply valuable data for the healthcare system and future epidemiological investigations more focused diagnostic guidelines. [ABSTRACT FROM AUTHOR]