Morphology, ploidy and molecular phylogenetics reveal a new diploid species from Africa in the baobab genus Adansonia (Malvaceae: Bombacoideae)

Abstract

The genus Adansonia has a disjunct geographical distribution: six species are endemic in Madagascar, one in Africa, and one in Australia. The well‐known African baobab (Adansonia digitata) is an iconic tree with considerable ethnobotanical significance. In contrast to the other seven species, which are diploid, A. digitata is tetraploid. A common ancestor of A. digitata and the other diploid baobab species would be diploid; however, there are no diploid species recorded on the African mainland. Examining variation in floral and pollen characters and chromosome number in specimens from Africa identified a new diploid baobab species, Adansonia kilima sp. nov., which co‐exists with A. digitata in Africa. Adansonia kilima is restricted to moderate elevations (650–1500 m), in contrast to A. digitata, which is widespread throughout Africa but prefers elevations below 800 m. Adansonia kilima is superficially similar to A. digitata, but can be differentiated on the basis of floral morphology, pollen, and chromosome number. We used two chloroplast DNA markers and the nuclear ITS to examine phylogenetic relationships within Adansonia. Three lineages were observed: one containing the Malagasy species, one containing the Australian species, and one containing the African species. The relationships between these clades were difficult to resolve, but a link between the African and Australian clades emerged when the analysis used fewer replicate samples of individual Malagasy taxa, included indel characters and included fewer outgroup taxa. The ITS phylogeny demonstrated that A. digitata and A. kilima are genetically similar, suggesting that tetraploidy evolved relatively recently.

Fatty Acid Composition of Baobab Seed and Its Relationship with the Genus Adansonia Taxonomy

“…Baobabs ( Adansonia genus, Bombacaceae family, super family of Malvaceae) are woody plants characteristic of the dry tropical forest ecosystems of Sub‐Saharan Africa, the North‐West of Australia, the west coast of Madagascar as well as the coastal vegetation of the Comoro Islands. The genus is represented by eight species, divided into three sections established on botanical and molecular characteristics . The Brevitubae section includes two Malagasy endemic species: A .…”

“…digitata (which is also present in the Comoros and in the northwest of Madagascar). Concerning this section, a controversy is opened: Petitgrew et al . identified, in 2012, a new species, present in Tanzania, Namibia, and South Africa.…”

The role of polyploidy in shaping morphological diversity in natural populations of Phlox amabilis

“…Many of the effects of polyploidy are genomic (Parisod et al, 2010; Gallagher et al, 2016), but understanding the association between polyploidy and morphology is important because the morphological differences between ploidies can have evolutionary and ecological consequences (Li et al, 1996; Segraves and Thompson, 1999; Husband and Schemske, 2000; Maherali et al, 2009; Khazaei et al, 2010; Zozomová‐Lihová et al, 2015; Segraves and Anneberg, 2016). Morphological data can also help resolve taxonomic issues in autopolyploid systems (reviewed by Soltis et al, 2007; Laport and Ramsey, 2015; e.g., Judd et al, 2007; Mráz et al, 2011; Pettigrew et al, 2012; Sosa and Dematteis, 2014). For these reasons, studies are needed to advance our understanding of the effects of polyploidy on morphological change of both vegetative and reproductive traits across the distribution of species, and in species with multiple ploidies (Balao et al, 2011; Richardson and Hanks, 2011; Sosa et al, 2012; Laport and Ramsey, 2015).…”

Combining an ancient tradition with modern developments: Latin and open access

“…A solution we endorse is for editors to require Latin diagnoses even though the Code currently allows English as an alternative and even if the anti-Latinists in the future succeed in removing from the Code the Latin allowance as an alternative to English . We are pleased that many authors publishing new taxa are continuing to use Latin for the diagnoses, including many in Taxon (e.g., Medina & al., 2012;Pettigrew & al., 2012).…”