Browsing by Author "Wilding, Nicholas"

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    Seasonal rainfall regime modulates genetic variation in the moss Pseudocrossidium crinitum
    (2009) Wilding, Nicholas; Hedderson, Terry A
    Patterns of genetic variation, resulting from Pliocene-Pleistocene climate shifts have been largely documented for species from Europe. However, little is known from Africa and especially South Africa, where climate shifts have often been invoked to explain the amazingly high diversity of the Cape Floristic Region. An analysis of cpDNA and nDNA sequence variation for 65 populations of the moss Pseudocrossidium crinitum across South Africa revealed the presence of a phylogeographic break corresponding to the split between the winter-rainfall zone (WRZ) and the all-year-(ARZ) and summer-rainfall zones (SRZ). Coalescent estimates of the time since these populations split (1.3 - 3.4 Mya) are highly consistent with the onset of winter-rainfall in the south-western Cape. Estimates of gene flow indicate much higher levels of gene flow into the WRZ, fitting the expected direction of gene flow based on wind patterns and differences in phenology. Haplotype diversity was observed to be highest in the WRZ, suggesting a number of genetic structuring factors in play within the WRZ. Additional analysis of populations from Chile and Lesotho suggest recent dispersal from Chile and possibly high levels of trans-continental gene flow between these populations. The study provides a first look at the genetic consequences of paleo-climate shifts on a moss species in South Africa. These results, in combination with other similar studies, may help to piece together the factors and processes responsible for the high diversity in the CFR today.
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    Systematics, biogeography and morphological evolution in Entosthodon Schwägr. (Bryopsida, Funariaceae) with a revision of the genus in Africa
    (2016) Wilding, Nicholas; Hedderson, Terry A
    Entosthodon Schwägr. (Funariaceae) is a genus of soil-inhabiting, annual to biennial mosses occurring worldwide in temperate to tropical-montane climates. Although a number of regional revisions and treatments exist for the genus, in many parts of the world, it remains poorly known. This is perhaps especially true in Africa, where the identities of most species names are obscure. Furthermore, recent work on the Funariaceae suggests that the sporophytes, long used as the main basis for classification and identification in the group, exhibit high levels of homoplasy and that Entosthodon is paraphyletic as currently circumscribed. I further test the monophyly of Entosthodon, and its relationships to other members of the Funarioideae, through phylogenetic analysis of DNA sequences from four chloroplast regions. These analyses included 45 Entosthodon species (ca. 50 % of those currently recognised), as well as an additional 22 species comprising representatives of all genera of the subfamily (except the rare, monotypic genera Cygnicollum, Clavitheca, Nanomitrella and Brachymeniopsis and the recently described monotypic Afoninia). Bayesian analyses of these data strongly contradict the monophyly of Entosthodon, and it is instead resolved as paraphyletic to a large clade comprising mostly members of Physcomitrium and Physcomitrella. Within this grade, five well supported lineages are resolved - the first comprises 3 species of Entosthodon and is sister to the second lineage, the monotypic Physcomitrellopsis. The third is sister to the afore mentioned i clades and comprises 11 species of Entosthodon within which the monotypic genus Funariella is embedded. The fourth lineage comprises 7 species of Entosthodon and is sister to a clade within which a Physcomitrium-Physcomitrella group is sister to the fifth lineage - a large clade comprising 24 species of Entosthodon. Entosthodon hungaricus is shown to belong in the Physcomitrium clade instead, consistent with its rostrate operculum. Based on the phylogeny, a new classification of Entosthodon sensu lato is proposed. The genus is split into 4 genera (Amphoritheca, Fifeobryum gen nov., Funariella and Entosthodon sens. str.) and the monophyletic Physcomitrellopsis is also maintained. Because of a lack of diagnostic morphological taxonomic characters this new classification is based largely on the molecular circumscription of clades. Nonetheless, particular character combinations do largely characterise most of these genera, albeit that frequent reversals render particular character states non-diagnostic. A revision of these five genera for Africa results in the recognition of twentysix species in total: three in Amphoritheca, 12 in Entosthodon, one in Physcomitrellopsis, one in Fifeobryum, and nine in Funariella. Six of these species, 4 in Entosthodon and 2 in Funariella, are newly described based on specimens from East and southern Africa. A key to the sub-Saharan species is provided, and each is fully described, mapped and illustrated.