Characterization and adaptive evolution of α‐tubulin genes in the Miscanthus sinensis complex (Poaceae)

Abstract

To investigate the organization of and mode of selection in the α-tubulin genes, full-length α-tubulin genes were cloned from four intraspecific taxa of Miscanthus sinensis and its close relatives M. floridulus and M. condensatus using standard polymerase chain reaction (PCR) and rapid amplification of genomic ends (RAGE)-PCR strategies. Genealogical analysis of angiosperms recovered a monophyletic group of Miscanthus α-tubulin genes, which is homologous to the tua5 locus of maize. Two clusters of nearly equal frequency revealed paraphyly within each Miscanthus taxon. Between-cluster recombination was frequent. Additional evidence for co-occurrence of two haplotypes within individuals and a large-scale crossover all suggested a likely allelic relationship between the Miscanthus clusters. Given a long between-species divergence time in Miscanthus, wide occurrence of the trans-species polymorphisms in α-tubulin genes and the approximately equal frequency of each allelic type make it extremely unlikely that α-tubulin diversity has been maintained under neutrality. Balancing selection may have contributed to such an apportioning of genetic variability as well as to high levels of genetic variation in α-tubulin and higher substitution rates at synonymous sites of exons than at intron bases of M. sinensis. In addition, certain effects of demographic oscillation may have distorted the scenario of a functional locus operating under balancing selection.

Population structure of Nouelia insignis (Asteraceae), an endangered species in southwestern China, based on chloroplast DNA sequences: recent demographic shrinking

“…A particular population genetic structure and the levels of genetic diversity within populations/species are usually results of various evolutionary forces acting in concert through time and space, and may therefore reflect effects of both historical and contemporary evolutionary events (Wu et al 2003). To distinguish the effects of these events, an endeavor has been accomplished by the use of gene genealogies upon which geographical information is incorporated in the search of association between genetic variation and geographical distribution (Avise 1998).…”

Adaptive divergence with gene flow in incipient speciation of Miscanthus floridulus/sinensis complex (Poaceae)

“…Compared with M. floridulus , which is more or less uniform morphologically, M . sinensis displays a wide array of morphs that correspond to intra‐specific taxa inhabiting various environments (Wu et al ., ). In Taiwan, there is an altitudinal cline of intra‐specific taxa (varieties) from sea level to high mountains.…”

“…The two species are distributed in East Asia, overlapping in southern Japan, Taiwan, and south-eastern China (Clifton-Brown et al, 2008, 2010. Compared with M. floridulus, which is more or less uniform morphologically, M. sinensis displays a wide array of morphs that correspond to intraspecific taxa inhabiting various environments (Wu et al, 2003). In Taiwan, there is an altitudinal cline of intraspecific taxa (varieties) from sea level to high mountains.…”

“…glaber in soil containing high copper or sulfur levels , represent local adaptation to an extreme habitat. Patches of these locally adapted variants may expand via their rhizomes, partly explaining the ecological abundance of Miscanthus (Wu et al, 2003). In addition, as for most other plants in Asia (Chiang and Schaal, 2006), Miscanthus has experienced post-glacial demographic expansion ; globally increasing temperatures may favor their growth, especially considering the high efficiency of C 4 photosynthesis.…”

Phylogeography of Angelica nitida (Apiaceae) endemic to the Qinghai–Tibet Plateau based on chloroplast DNA sequences

“…Various evolutionary forces acting in concert through time and space influence genetic structure and diversity within a particular population/species. The population genetic structure might also reflect the effects of both historical and contemporary evolutionary events (Wu et al, ). Phylogeography, which uses geographical information to characterize the association between genetic variation and geographical distribution (Avise, ), has been implemented in studies to distinguish the effects of these events.…”