International Journal of Molecular Evolution and Biodiversity, 2025, Vol.15, No.1, 40-50 http://ecoevopublisher.com/index.php/ijmeb 42 Figure 1 Pineapple population structure and admixture (Adopted from Chen et al., 2019) Image caption: a: SplitsTree network for Ananas accessions excluding admixed samples. Green, variety microstachys; red, variety erectifolius; orange, variety bracteatus; yellow, variety comosus/Mordilona-related cultivars Cambray/Monte Lirio; purple, variety comosus/cultivar Singapore Spanish; light blue, variety comosus/cultivar Smooth Cayenne; dark blue, variety comosus/cultivar Queen; brown, genus Pitcairniaoutgroups. A network of admixed samples is shown in Supplementary; b: MDS graphs of the studied Ananas accessions, with horizontal and vertical axes explaining 33.0% and 20.6% of the variance, respectively; color code follows that in a and admixed A. comosus genotypes are indicated in gray; c: Ancestry results from ADMIXTURE under the K = 8 model supported by an examination of cross-validation errors (Adopted from Chen et al., 2019) 3.2 Molecular phylogenetic studies based on organelle and nuclear genomes Earlier DNA studies using plastid DNA or AFLP markers could not clearly show the family tree. But now, full organelle genomes and many SNP markers give better data. For example, A. comosus var. erectifolius is very close to A. comosus in plastid genome trees (Liu et al., 2022). Studies using nuclear genome SNPs also show only small differences among Ananas types. A tree made from about 7.2 million SNPs shows clear groups within A. comosus, like the “Spanish” group, the “Queen/Cayenne” group, and different lines for wild A. bracteatus and A. microstachys (Feng et al., 2022). All Ananas types fall into a single group, and the species once called Pseudananas sagenarius is actually part of Ananas (Ouyang et al., 2022). 3.3 Phylogenetic placement of ananas within bromeliaceae and poales Inside the subfamily Bromelioideae, Ananas stands out. Most members of this group live on trees (epiphytes), but Ananas grows on the ground and uses CAM photosynthesis strongly. Studies have confirmed that Bromelioideae is one group and that Ananas is closely related to Bromelia. These two likely share a common ancestor. Nuclear and chloroplast genes have helped show deeper family links within Bromeliaceae (Ouyang et al., 2022). At the level of the plant order Poales, full genome data shows that Bromeliaceae (and Ananas) split from the rest of the group before the grass family (Poaceae) did (Feng et al., 2022).
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