Austinia, a new genus of Convolvulaceae is described and its relationship with other genera is discussed. Two species previously placed in Jacquemontia are referable to the genus. However, a revision of species delimitation demonstrates that the two are conspecific. Austinia therefore comprises a single species, endemic to Brazil.
In 1866, the botanist Joseph Dalton Hooker delivered a lecture to the British Association for the Advancement of Science in Nottingham, U.K. entitled Insular floras.The lecture has been described as "the first systematic statement of the importance of islands for evolutionary studies".As such, it can be seen to have contributed to the development of the "natural laboratory paradigm" that views islands as model systems for studying ecology and evolution.Hooker's lecture also highlighted another key driver in shaping island diversity patterns, namely human impact.How and when does human impact compromise the utility of islands as 'natural laboratories' for studying evolution?To date, no fewer than eight "shortfalls" -knowledge gaps that impact on studies of biodiversity-have been described.In this paper, we suggest that a further shortfall is in order -a Hookerian shortfall-to account for uncertainty in the extent to which biodiversity patterns reflect natural rather than anthropogenic processes.
Two endemic species of Leontodon are currently recognized in the Azores archipelago: Leontodon filii and L. rigens. However, there has been confusion regarding the application of these names and field observations and herbarium studies suggested three morphotypes in the islands. Here, we present a taxonomic revision of the Azorean endemic Leontodon species using morphological characters and new molecular data from the ITS region and from three chloroplast regions: trnQ, trnV and matK. Fifty-one quantitative and qualitative morphological characters were examined that revealed consistent differences between specimens from the western, central and eastern subarchipelagos (where, on the latter, Leontodon is restricted to São Miguel). Molecular analysis revealed two well defined monophyletic groups, one comprising accessions from São Miguel and the second comprising accessions from the western group, while central group accessions were in an unresolved polytomy. Both analyses also indicated the occurrence of hybridization with L. saxatilis, a widespread non-endemic species. Taken together, molecular and morphological data suggest the reinstatement of a third Azorean Leontodon taxon endemic to the western group. A key to the Leontodon of the Azores and descriptions of the endemic taxa are provided.
Biological collections, including herbarium specimens, are unique sources of biodiversity data presenting a window on the history of the development and accumulation of knowledge of a specific geographical region. Understanding how the process of discovery impacts that knowledge is particularly important for oceanic islands which are often characterized by both high levels of endemic diversity and high proportions of threatened taxa. The archipelagos of the Macaronesian region (i.e. Azores, Canaries, Savages, Madeira, and Cabo Verde) have been the focus of attention for scientific expeditions since the end of the 17th century. However, there is no integrated study describing the historical process of collecting, discovery and description of its flora. Using as a case study the Cabo Verde endemic angiosperm flora, we review the history of collecting in the flora and apply a Bayesian approach to assess the accumulation of species discovery, through time and space across the nine islands of the archipelago. Our results highlight the central role not only of natural characteristics (e.g. area, age, maximum altitude and average value of the terrain ruggedness index) but also historical factors (i.e. the location of major harbors) for the development of knowledge of the flora. The main factors that have determined the process of species description in the archipelago and how this impact our understanding of diversity patterns across archipelagos are discussed.
Phylogenetic analysis has revealed that Argyranthemum broussonetii is polyphyletic, with subsp. broussonetii (Tenerife) and subsp. gomerensis (La Gomera) resolved in separate clades within the Macaronesian endemic genus Argyranthemum. We show that A. broussonetii subsp. broussonetii and subsp. gomerensis are similar in leaf traits, likely a consequence of adaptation to similar habitats, but that the two can readily be distinguished based on capitula and cypselae characteristics. Indeed, A. broussonetii subsp. gomerensis was found to share greater affinity with A. callichrysum, also from La Gomera based on capitula and cypselae characters, in agreement with its phylogenetic placement. Therefore, we propose that A. broussonetii subsp. gomerensis should be recognized as a subspecies of A. callichrysum, specifically A. callichrysum subsp. gomerensis. A key to differentiate A. broussonetii, A. callichrysum subsp. callichrysum and subsp. gomerensis is provided.Citation: White O. W., Reyes-Betancort J. A., Chapman M. A. & Carine M. A. 2021: Recircumscription of the Canary Island endemics Argyranthemum broussonetii and A. callichrysum (Asteraceae: Anthemideae) based on evolutionary relationships and morphology. – Willdenowia 51: 129–139.Version of record first published online on 29 April 2021 ahead of inclusion in April 2021 issue.
Oceanic island endemics typically exhibit very restricted distributions. In Macaronesia, only one endemic angiosperm species, Ranunculus cortusifolius, has a distribution spanning the archipelagos of the Azores, Madeira, and Canaries. Earlier work suggested possible differences between archipelagos and the multiple origins of the species. This paper tests the hypothesis that R. cortusifolius is a single widespread Macaronesian endemic species with a single origin.Chloroplast (matK-trnK, psbJ-petA) and ITS sequences were generated from across the distribution of R. cortusifolius. Relationships were investigated using Bayesian inference and divergence times estimated using BEAST. Infraspecific variation was investigated using statistical parsimony. The general mixed Yule-coalescent model (GMYC) was further used to identify putative species boundaries based on maternally inherited plastid data.The hypothesis of multiple independent origins of R. cortusifolius is rejected. Divergence of the R. cortusifolius lineage from a western Mediterranean sister group in the late Miocene is inferred. Distinct genotypes were resolved within R. cortusifolius that are endemic to the Azores, Madeira, and the Canaries. Four to five putative species were delimited by different versions of the GMYC model.Ranunculus cortusifolius is the result of a single colonization of Macaronesia. The large distances between archipelagos have been effective barriers to dispersal, promoting allopatric diversification at the molecular level with diversification also evident within the Canaries. Isolation has not been accompanied by marked morphological diversification, which may be explained by the typical association of R. cortusifolius with stable and climatically buffered laurel forest communities.
Oceanic islands offer unparalleled opportunities to investigate evolutionary processes such as adaptation and speciation. However, few genomic resources are available for oceanic island endemics. In this study, we publish transcriptome sequences from three Macaronesian endemic plant species (Argyranthemum broussonetii [Asteraceae], Descurainia bourgaeana [Brassicaceae], and Echium wildpretii [Boraginaceae]) that are representative of lineages that have radiated in the region. In addition, the utility of transcriptome data for marker development is demonstrated.Transcriptomes from the three plant species were sequenced, assembled, and annotated. Between 1972 and 2282 simple sequence repeats (SSRs) were identified for each taxon. Primers were designed and tested for 30 of the candidate SSRs identified in Argyranthemum, of which 12 amplified well across three species and eight were polymorphic.We demonstrate here that a single transcriptome sequence is sufficient to identify hundreds of polymorphic SSR markers. The SSRs are applicable to a wide range of questions relating to the evolution of island lineages.
[m]3ta is a method that seeks to implement a taxic view of homology. The method is consistent with Patterson's tests for discriminating homology from nonhomology. Contrary to the claims of Kluge and Farris, (1999, Cladistics 15, 205–212), m3ta is not a phenetic method—nor does it necessarily place the basal split in a tree between the phenetically most divergent taxa. [m]3ta does not seek to accurately recover phylogeny but rather it seeks to maximize the information content of taxic homology propositions. [m]3ta is a method of classification in which the unit of analysis is the relation of homology. [m]3ta differs from all phylogenetic methods because the units of analyses in phylogenetic methods, including sca, are transformation series.
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