Trichome micromorphology in Alcea L. and allied genera (Malvaceae) and its systematic implication

Trichomes of 26 species of Alcea (Malvaceae) were investigated using light (LM) and scanning electron microscopy (SEM). The trichomes show a great micromorphological variation, which provides data useful for species delimitation in Alcea. Two basic types of trichomes could be distinguished in Alcea and allied genera: glandular and eglandular. The glandular trichomes could in turn be subdivided into two subtypes: capitate and clavate. The eglandular trichomes could be subdivided into five subtypes: simple, fascicled, stellate, fascicled-stellate and pluri-radiate. Characters of taxonomic interest are: trichome density (glabrous to dense), number of arms per trichome, orientation relative to the epidermal surface (appressed to erect) and presence/absence of a stalk. According to the results the species of Alcea can be divided into four informal groups based on trichome types. The results further support the exclusion of the annual Althaea species from the perennial ones and their close relationship to Malva. In addition, a close relationship between perennial Althaea and basal Alcea lineages is supported. Based on the evolutionary framework provided by recent molecular phylogenetic investigations, the following trends can be observed in the Malva alliance: long and narrow-armed trichomes are primitive in relation to short and thick-armed trichomes; dense indumentum coverage is primitive in relation to moderately dense or glabrous ones; presence of simple hairs on stem (particularly on leaves) is more advanced than their absence; spreading villous-stellate and fascicled trichomes are more advanced than appressed stellate ones. Clavate trichomes, which were found exclusively in a few species of Alcea, should be considered as a derived state in relation to capitate ones, and they may provide a synapomorphy for the crown group of Alcea.     

Comparative analysis of fish environmental DNA reveals higher sensitivity achieved through targeted sequence-based metabarcoding

Environmental DNA (eDNA)-based methods of species detection are enabling various applications in ecology and conservation including large-scale biomonitoring efforts. qPCR is widely used as the standard approach for species-specific detection, often targeting a fish species of interest from aquatic eDNA. However, DNA metabarcoding has the potential to displace qPCR in certain eDNA applications. In this study, we compare the sensitivity of the latest Illumina NovaSeq 6000 NGS platform to qPCR TaqMan assays by measuring limits of detection and by analysing eDNA from water samples collected from Churchill River and Lake Melville, NL, Canada. Species-specific, targeted next generation sequencing (NGS) assays had significantly higher sensitivity than qPCR, with limits of detection 14- to 29-fold lower. For example, when analysing eDNA, qPCR detected Gadus ogac (Greenland cod) in 21% of samples, but targeted NGS detected this species in 29% of samples. General NGS assays were as sensitive as qPCR, while simultaneously detecting 15 fish species from eDNA samples. With over 34,000 fish species on the planet, parallel and sensitive methods such as NGS will be required to support effective biomonitoring at both regional and global scales.