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-a-b. Relative frequency of seedlings in different genome sizes (nuclear DNA content estimates) for two Eriotheca spp. (Malvaceae) with different cytotypes -a. seedlings from Eriotheca gracilipes (Eg) diploid (Eg2x, n = 51) and hexaploid (Eg6x, n = 65) mother-plants; b. seedlings from Eriotheca pubescens (Ep) tetraploid (Ep4x, n = 151) and hexaploid (Ep6x, n = 130) mother-plants. Peaks represent prevalent genome size in each species or cytotype. A secondary peak in hexaploidy E. gracilipes may be the result of aneuploidy.
Source publication
Hybridization and changes in ploidy have been associated with shifts from sexuality to apomixis, and may explain isolation among populations and species. Hybrids resulting from interploidy crosses may contribute to a broader understanding of how these populations and species have originated and evolved. Stomatal morphometrics and flow cytometry ana...
Contexts in source publication
Context 1
... flow cytometry genome size estimates showed a clear distinction and limited overlap between species cytotypes (Fig. 2). Seedlings from diploid E. gracilipes had the smallest DNA content (mean = 3.66 pg; standard deviation = 0.09; range In both panels, seedlings from Eriotheca estevesiae from diploid mother-plants ( Ee2x, green color); Eriotheca gracilipes (Eg) from diploid (Eg2x, white color) and hexaploid (Eg6x, white color) mother-plants and their ...
Context 2
... overlapped broadly but were statistically different (X 2 = 7.26; d.f. = 1; p = 0.007). As a whole, genome sizes estimates were compatible with ploidy levels, and there were no intermediate DNA content measurements which suggested natural hybrids. The wider genome size variation and a second smaller peak observed for E. gracilipes hexaploids (Fig. 2a) may be due to aneuploidy or further anomalies which remain to be studied. But since it represents higher DNA content, it is not possibly related to hybridization with lower ploidy ...
Citations
... The Cerrado Eriotheca (ca. 10 out of 30 accepted species) seem to have originated <10 mya and are associated with the rise of seasonal C 4 grass savanna environments and frequent fires (Simon & Pennington, 2012). Despite sympatry and breeding similarities, common Cerrado Eriotheca are not sister groups, and hybridization does not seem to be common, although it cannot be ruled out (Serra et al., 2022). ...
... These mixed populations may evidence gene flow between apomictic and sexual individuals and, in some cases, may promote the restoration of genetic variability in apomictic lineages (Karunarathne & Hojsgaard, 2021). But, as previously mentioned, hybridization does not seem to be common (Serra et al., 2022). ...
Polyploidy and whole genome duplication are major evolutionary drivers in plants. Climate variations during the Pleistocene have influenced distribution and range expansion worldwide. Similar trends have been reported for Cerrado plants, but no attempt has been made to link phylogeography with ploidy and breeding changes. Thus, we aimed here (1) to assess ploidy and genome size of Eriotheca estevesiae Carv.-Sobr., and compare it with E. pubescens (Mart.) Schott & Endl. (Both included into the Eriotheca Stellate Trichome Species Complex - ESTSC). (2) Subsequently, we investigated their phylogeography to see whether genetic structure and range expansion trends were similar to those previously described for the Cerrado biome. Finally (3), we discussed whether ESTSC phylogeographical patterns could be associated to geographical parthenogenesis processes. Common cytogenetic techniques and flow cytometry were used to confirm chromosome number and genome size of E. estevesiae. We used three cpDNA regions to analyse 14 ESTSC Cerrado populations, for which we obtained also ploidy level and breeding information. We investigated haplotype diversity, population structure and tested neutrality, aiming at reconstructing phylogeographic scenarios. We found three ploidy levels and eight cpDNA haplotypes in ESTSC, one of them shared by most populations. Haplotype and ploidy distribution corroborated the idea that E. pubescens, the widely distributed polyploid and apomictic species, may have originated from northern diploid and probably sexual E. estevesiae. Matrilinear cpDNA links support the idea that apomixis and polyploidy in ESTSC may have allowed range expansion during the Pleistocene, in a process analogous to the geographic parthenogenesis described elsewhere.
