Mutational meltdown or controlled chain reaction: The dynamics of rapid plastome evolution in the hyperdiversity of Poaceae.

Autor: Wang, Jie, Fu, Gao‐Fei, Tembrock, Luke R., Liao, Xue‐Zhu, Ge, Song, Wu, Zhi‐Qiang
Předmět:
Zdroj: Journal of Systematics & Evolution; Mar2023, Vol. 61 Issue 2, p328-344, 17p
Abstrakt: The study of genomic structural evolution associated with accelerated evolutionary rates that result in avoidance of meltdown and increase biodiversity is becoming ever more possible as the number of available plastomes increases. To more comprehensively analyze rate heterogeneity among monocots and within Poaceae, we sequenced plastomes from four Poaceae species, combined them with publicly available data from ~200 plastomes, and conducted comparative analyses to quantify the pattern of rate heterogeneity between different lineages, functional groups, and periods of evolutionary time. We compared structural differences across the Poaceae to quantify how changes in plastome size correspond to different genomic subunits and the evolution of IR–SC junction boundaries. The substitution rates among ancestral Poaceae were inferred to be exceptionally rapid compared to other monocots but slowed after divergence into extant lineages, which could not be sufficiently explained by positive selection. As such, rapid rates in the ancestral lineage leading to Poaceae might be more closely linked to large‐scale structural changes like the loss of ycf1 and ycf2. The total increase in plastome size across Poaceae was positively correlated with the total length of intergenic spacers, tandem repeats, and dispersed repeats as well as large single copy, and inverted repeats (IRs). The continuous evolution of IR–SC junction boundaries was asynchronous with sizes of total genome and subunits across Poaceae. Future work is needed to better understand what factors in ancestral Poaceae evolved to harness such rapid rates of plastome evolution, avoid a mutational meltdown, and escape the stagnation of strong purifying selection as well as if these factors could be utilized to synthetically control rates. Highlights: Extensive sampling covering all monocotyledonous orders and subfamilies of Poaceae to compare different levels of plastome evolutionary rates heterogeneity.Comprehensively revealed the clade‐specific patterns of plastomes size variations among Poaceae subfamilies.Confirmed the distances of genes to IR–SC boundaries were effective for phylogeny, species identification, and maternal tracing of Poaceae species. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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