Analyses of amplified fragment length polymorphisms (AFLP) indicate rapid radiation of Diospyros species (Ebenaceae) endemic to New Caledonia

Abstract

BackgroundRadiation in some plant groups has occurred on islands and due to the characteristic rapid pace of phenotypic evolution, standard molecular markers often provide insufficient variation for phylogenetic reconstruction. To resolve relationships within a clade of 21 closely related New Caledonian Diospyros species and evaluate species boundaries we analysed genome-wide DNA variation via amplified fragment length polymorphisms (AFLP).ResultsA neighbour-joining (NJ) dendrogram based on Dice distances shows all species except D. minimifolia, D. parviflora and D. vieillardii to form unique clusters of genetically similar accessions. However, there was little variation between these species clusters, resulting in unresolved species relationships and a star-like general NJ topology. Correspondingly, analyses of molecular variance showed more variation within species than between them. A Bayesian analysis with BEAST produced a similar result. Another Bayesian method, this time a clustering method, Structure, demonstrated the presence of two groups, highly congruent with those observed in a principal coordinate analysis (PCO). Molecular divergence between the two groups is low and does not correspond to any hypothesised taxonomic, ecological or geographical patterns.ConclusionsWe hypothesise that such a pattern could have been produced by rapid and complex evolution involving a widespread progenitor for which an initial split into two groups was followed by subsequent fragmentation into many diverging populations, which was followed by range expansion of then divergent entities. Overall, this process resulted in an opportunistic pattern of phenotypic diversification. The time since divergence was probably insufficient for some species to become genetically well-differentiated, resulting in progenitor/derivative relationships being exhibited in a few cases. In other cases, our analyses may have revealed evidence for the existence of cryptic species, for which more study of morphology and ecology are now required.

Growth form evolution and hybridization in Senecio (Asteraceae) from the high equatorial Andes

“…The present study, using ITS sequences and an extended list of species, suggests monophyly of the Lasiocephalus ‐ Culcitium species group but with neither of the two former genera monophyletic. Although relationships within the group are only partly resolved in both the ITS and AFLP datasets, suggesting a recent diversification (Turner et al., ), there is a partial congruence between the two markers, as AFLP cluster C corresponds to the ITS “páramo clade” (except for Senecio nivalis ) and AFLP clusters A and B correspond to the ITS “forest clade” (except for S. puracensis ) (Figure , Table ); incongruences will be discussed below.…”

“…Although relationships within the group are only partly resolved in both the ITS and AFLP datasets, suggesting a recent diversification (Turner et al, 2013), there is a partial congruence between the two markers, as AFLP cluster C corresponds to the ITS "páramo clade" (except for Senecio nivalis) and AFLP clusters A and B correspond to the ITS "forest clade" (except for S. puracensis) ( Figure 6, Table 1); incongruences will be discussed below.…”

Origins of the fern genus Hymenophyllum (Hymenophyllaceae) in New Caledonia: Multiple independent colonizations from surrounding territories and limited in situ diversification

“…For H. deplanchei, H. subobtusum and H. leratii, other possible source areas are Southeast Asia, Australia and other Pacific Islands. Whereas LDD from Australia to NC has been shown in several groups (see references in Introduction), cases of LDD from Southeast Asia and NZ to NC are less common (but for Southeast Asia see studies on Piper L., Piperaceae; and Diospyros L., Ebenaceae;Turner & al., 2013). However, a key role of NZ in the origin of the NC flora was suggested by Pole (2010) based on the presence, in the NZ fossil record, of lineages that are now restricted to NC.…”

Island life - classification, speciation and cryptic species ofPycnandra(Sapotaceae) in New Caledonia

“…Detecting the presence of cryptic species has implications for classification, conservation and biogeography. In New Caledonia, only two cases of cryptic flowering plant species have been revealed, in Spiraeanthemum A.Gray (Cunoniaceae; Pillon et al ., ) and Diospyros L. (Ebenaceae; Turner et al ., ). However, based on unpublished molecular data, Swenson & Munzinger () indicated that cryptic species might be present in Pycnandra .…”