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<jats:title>Abstract</jats:title><jats:p>One of the most fascinating phenomena in evolutionary biology is the rapid evolution of genes with conserved functions across the tree of life. Because the cellular and organismal development processes are highly conserved across eukaryotes, a naive evolutionary expectation is that the genes involved in those processes would also be under high selective constraint and evolve extremely slowly. However, we now know that evolutionarily young genes can rapidly acquire crucial viability functions and even evolutionarily old genes can have unexpected levels of rapid evolution within specific lineages (Talbert et al. 2004). These studies have led to novel insights of function and evolution in molecular systems that are universally important for almost all organisms.</jats:p><jats:p>This article is protected by copyright. All rights reserved.</jats:p>

<jats:title>ABSTRACT</jats:title><jats:sec><jats:title>Premise</jats:title><jats:p>Species delimitation is an integral part of evolution and ecology and is vital in conservation science. However, in some groups species delimitation is difficult, especially where ancestral relationships inferred from morphological or genetic characters are discordant, possibly due to a complicated demographic history (e.g., recent divergences between lineages). Modern genetic techniques can take account of complex histories to distinguish species at a reasonable cost and are increasingly used in numerous applications. We focus on the scribbly gums, a group of up to five closely related and morphologically similar ‘species’ within the eucalypts.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Multiple populations of each recognized scribbly gum species were sampled over a wide region across climates and genome‐wide scans used to resolve species boundaries.</jats:p></jats:sec><jats:sec><jats:title>Key results</jats:title><jats:p>We found that none of the taxa were completely diverged, and there were two genetically distinct entities: the inland distributed <jats:italic>Eucalyptus rossii</jats:italic> and a coastal conglomerate consisting of four species forming three discernible, but highly admixed groups. Divergence among taxa was likely driven by temporal vicariant processes resulting in partial separation across biogeographic barriers. High interspecific gene flow indicated separated taxa reconnected at different points in time blurring species boundaries.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Our results highlight the need for genetic screening when dealing with closely related taxonomic entities, particularly those with modest morphological differences. We show that the use of high throughput sequencing can be effective at identifying species groupings and processes driving divergence, even in the most taxonomically complex groups, and support it as a standard practice for disentangling species complexes.</jats:p><jats:p>This article is protected by copyright. All rights reserved.</jats:p></jats:sec>

<jats:title>Abstract</jats:title><jats:p>One of the most remarkable innovations in the evolution of vascular plants is secondary growth: the developmental process by which plants grow thicker. The textbook illustration of secondary growth––a core of secondary xylem surrounded by a sheath of secondary phloem––is generated through a cylindrical meristem called the vascular cambium (Fig. 1A). This modality is conserved across thousands of species, providing mechanical support for ever‐elongating shoots, and a regenerative source of vascular tissues to feed the ever‐expanding crown of branches and leaves</jats:p><jats:p>This article is protected by copyright. All rights reserved.</jats:p>

<jats:title>Abstract</jats:title><jats:sec><jats:title>Premise</jats:title><jats:p>Dominant in many ecosystems around the world, clonal plants can reach considerable ages and sizes. Due to their modular growth patterns, individual clonal plants (genets) can consist of many subunits (ramets). Since single ramets do not reflect the actual age of genets, the ratio between genet size (radius) and longitudinal annual growth rate (LAGR) of living ramets is often used to approximate the age of clonal plants. However, information on how the LAGR changes along ramets and how LAGR variability may affect age estimates of genets is still limited.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>We assessed the variability of LAGR based on wood‐section position along the ramets and on the duration of the growing season on three genetically distinct genets of <jats:italic>Salix herbacea</jats:italic> growing in the Northern Apennines (Italy). We compared genet ages estimated by dividing genet radius by the LAGRs of its ramets.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>LAGR increased significantly from the stem apex to the root collar; indicating that ramet growth rate decreased with time. Furthermore, a difference of ca. 2 weeks in the onset of the growing period did not impact LAGR. Considering the high LAGR variability, we estimated that the three genets started to grow between ~2100 and ~7000 years ago, which makes them the oldest known clones of <jats:italic>S. herbacea</jats:italic> even considering the most conservative age estimate.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Our findings indicate that analyzing ramets at the root collar provides an integrative measurement of their overall LAGR, which is crucial for estimating the age of genets.</jats:p></jats:sec>