Publications by authors named "Aaron H Kennedy"
Background And Aims: Heterotrophic plants have long been a challenge for systematists, exemplified by the base of the orchid subfamily Epidendroideae, which contains numerous mycoheterotrophic species.
Methods: Here we address the utility of organellar genomes in resolving relationships at the epidendroid base, specifically employing models of heterotachy, or lineage-specific rate variation over time. We further conduct comparative analyses of plastid genome evolution in heterotrophs and structural variation in matK.
Article Synopsis
- Publicly available DNA reference sequences play a crucial role in helping plant protection organizations identify and manage fungal pathogens that threaten agricultural trade.
- The RefSeq Targeted Loci (RTL) project at NCBI offers a comprehensive database containing curated fungal internal transcribed spacer (ITS) sequences and verified species associations for over 12,000 fungal species.
- The study highlights the effectiveness of certain marker loci for phylogenetic analysis, addresses species misidentification issues caused by single-locus approaches, and notes that some species-level identifications remain challenging due to novel species diversity and unresolved lineage relationships.
Unprecedented Parallel Photosynthetic Losses in a Heterotrophic Orchid Genus.
Mol Biol Evol
September 2019
Article Synopsis
- Heterotrophic plants like the leafless orchid genus Hexalectris showcase significant evolutionary changes in their genomes and physiology, but gaps in genomic data remain.
- This study sequenced complete plastid genomes for Hexalectris and its relatives to identify independent losses of photosynthesis and understand the genetic degradation process resulting from relaxed natural selection.
- Findings reveal four to five separate losses of photosynthesis in Hexalectris, highlighting variations in gene loss and suggesting that the number of independent transitions to a mycoheterotrophic lifestyle among land plants is likely underestimated, emphasizing the need for thorough genomic studies for better insights into plant evolution.
Heterotrophic plants provide evolutionarily independent, natural experiments in the genomic consequences of radically altered nutritional regimes. Here, we have sequenced and annotated the plastid genome of the endangered mycoheterotrophic orchid Hexalectris warnockii. This orchid bears a plastid genome that is ∼80% the total length of the leafy, photosynthetic Phalaenopsis, and contains just over half the number of putatively functional genes of the latter.
View Article and Find Full Text PDFHybridization is an important evolutionary factor in the diversification of many plant and animal species. Of particular interest is that historical hybridization resulting in the origin of new species or introgressants has occurred between species now geographically separated by great distances. Here, we report that Senecio massaicus, a tetraploid species native to Morocco and the Canary Islands, contains genetic material of two distinct, geographically separated lineages: a Mediterranean lineage and a mainly southern African lineage.
View Article and Find Full Text PDFOne of the longstanding questions in phylogenetic systematics is how to address incongruence among phylogenies obtained from multiple markers and how to determine the causes. This study presents a detailed analysis of incongruent patterns between plastid and ITS/ETS phylogenies of Tribe Senecioneae (Asteraceae). This approach revealed widespread and strongly supported incongruence, which complicates conclusions about evolutionary relationships at all taxonomic levels.
View Article and Find Full Text PDFArticle Synopsis
- Mycoheterotrophic plants, such as certain orchids, have evolved to rely entirely on mycorrhizal fungi for carbon instead of photosynthesis, with the Orchidaceae family hosting the most species.
- This study is the first to analyze the mycorrhizal partners of all species within a specific genus of mycoheterotrophic orchids (Hexalectris), revealing distinct fungal associations for each species examined.
- The findings indicate strong evolutionary pressure for these orchids to develop unique mycorrhizal connections, suggesting rapid changes in how they associate with these fungi over time.
Conidial dispersal in Stachybotrys chartarum in response to low-velocity airflow was studied using a microflow apparatus. The maximum rate of spore release occurred during the first 5 min of airflow, followed by a dramatic reduction in dispersal that left more than 99% of the conidia attached to their conidiophores. Micromanipulation of undisturbed colonies showed that micronewton (microN) forces were needed to dislodge spore clusters from their supporting conidiophores.
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