Lethal Gene-Combinations and Pollen Sterility in Diploid Apple Varieties

Heilborn, Otto

doi:10.1111/j.1601-5223.1932.tb02559.x

Cited by 4 publications

(1 citation statement)

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“…Polyploidy, on the contrary, is more frequent in the genera Schoenus and Eleocharis (Elliott et al ., 2022) and less common in Carex than in other Cyperaceae genera (Roalson, 2008). Polyploidy was hypothesized to be rare in Carex due to the disintegration of three nuclei after meiosis (pseudomonads instead of tetrads) making unreduced gametes much less likely to be formed (Heilborn, 1932), although it is unclear whether this cytogenetic peculiarity is unique to Carex or shared with other Cyperaceae species (Simpson et al ., 2003). The known differences in the mode of chromosome evolution in this family makes this lineage ideal to test heterogeneous patterns of chromosome evolution.…”

Section: Resultsmentioning

confidence: 99%

A non‐homogeneous model of chromosome‐number evolution to reveal shifts in the transition patterns across the phylogeny

2023

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Changes in chromosome numbers, including polyploidy and dysploidy events, play a key role in eukaryote evolution as they could expediate reproductive isolation and have the potential to foster phenotypic diversification. Deciphering the pattern of chromosome-number change within a phylogeny currently relies on probabilistic evolutionary models. All currently available models assume time homogeneity, such that the transition rates are identical throughout the phylogeny.Here, we develop heterogeneous models of chromosome-number evolution that allow multiple transition regimes to operate in distinct parts of the phylogeny. The partition of the phylogeny to distinct transition regimes may be specified by the researcher or, alternatively, identified using a sequential testing approach. Once the number and locations of shifts in the transition pattern are determined, a second search phase identifies regimes with similar transition dynamics, which could indicate on convergent evolution.Using simulations, we study the performance of the developed model to detect shifts in patterns of chromosome-number evolution and demonstrate its applicability by analyzing the evolution of chromosome numbers within the Cyperaceae plant family.The developed model extends the capabilities of probabilistic models of chromosomenumber evolution and should be particularly helpful for the analyses of large phylogenies that include multiple distinct subclades.

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