Nuclear microsatellite variation in Malagasy baobabs (Adansonia, Bombacoideae, Malvaceae) reveals past hybridization and introgression

Abstract

The clear genetic differentiation observed between the six species may reflect their adaptation to different assortments of climate regimes and habitats during the colonization of the island. Microsatellite variation reveals that hybridization probably occurred in secondary contact between species of section Longitubae. This type of hybridization may also have been involved in the differentiation of a local new stabilized entity showing specific microsatellite alleles and morphological characters, suggesting a potential role of hybridization in the recent history of diversification on Madagascar.

Interspecies gene flow is a key evolutionary process for the adaptation of long-lived species to new environmental conditions

“…identified at the site. Both parental species are endemic to the island, have distinct geographical ranges and differ in important adaptive traits (Leong Pock Tsy et al, 2013 Este número ha recibido una ayuda del Vicerrectorado de Investigación y Transferencia de Conocimiento de la Universidad de Alicante…”

“…& H. Perr. (Leong Pock Tsy et al, 2013). A change in flowering phenology compared to the parental species was observed in Quercus afares Pomel (Mir et al, 2006) and Yucca gloriosa L. (Rentsch & Leebens-Mack, 2012), whereas ethological isolation was suggested for Stenella clymene Cray (the clymene dolphin) (Amaral et al, 2014) (Table 1).…”

Chemical characterization of floral scents in the six endemic baobab species (Adansonia sp.) of Madagascar

“…For example, all emit floral fragrances characterised by the presence of a high proportion of 2-phenylacetonitrile. The presence of these common compounds in the floral fragrances of the entire Longitubae section of baobabs appears to increase the probability of interspecific crosses within the section and thus to be an essential factor in the introgression phenomenon demonstrated by DNA analysis by Leong Pock Tsy et al (2013). Genetic introgression derives from a backcross of a hybrid with one of the parental species resulting in an individual which is morphologically identical to one species whilst retaining parts of the other genomes (Jimenez et al, 2004;Lumaret et al, 2005;Heuertz et al, 2006;Duminil et al, 2006).…”

“…Ryckewaert et al, 2011. The introgression phenomenon was described by Leong Pock Tsy et al (2013) in the Longitubae species. It was a form of evolution and an adaptive response generally found in species having a long life cycle (Jimenez et al, 2004;Lumaret et al, 2005;Heuertz et al, 2006;Duminil et al, 2006).…”

“…There are nine species of the Adansonia genus (belonging to the Malvaceae family) in the world, seven of which are present in Madagascar including the African species, Adansonia digitata; the other six species are endemic (Perrier de la Bâthie and Hochreutiner, 1955;Baum, 1995aBaum, , 1995bPettigrew et al, 2012;Leong Pock Tsy et al, 2013). These species are characteristic of Madagascar's dry regions and are of great scientific, economic and cultural interest.…”