PubMed · 11638823
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C Becela-Deller. 1998. [Not Available].. https://pubmed.ncbi.nlm.nih.gov/11638823/
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The transition from outcrossing to self-fertilization is one of the most common evolutionary trends in plants. Reproductive assurance, where self-fertilization ensures seed production when pollinators and/or potential mates are scarce, is the most long-standing and most widely accepted explanation for the evolution of selfing, but there have been few experimental tests of this hypothesis. Moreover, many apparently adaptive floral mechanisms that ensure the autonomous production of selfed seed might use ovules that would have otherwise been outcrossed. This seed discounting is costly if selfed offspring are less viable than their outcrossed counterparts, as often happens. The fertility benefit of reproductive assurance has never been examined in the light of seed discounting. Here we combine experimental measures of reproductive assurance with marker-gene estimates of self-fertilization, seed discounting and inbreeding depression to show that, during 2 years in 10 Ontario populations of Aquilegia canadensis (Ranunculaceae), reproductive assurance through self-fertilization increases seed production, but this benefit is greatly outweighed by severe seed discounting and inbreeding depression.
We study the non-genetic inheritance of fertility from parents to offspring. For this purpose, we propose an exchangeable extension of the Wright-Fisher model. This extension allows us to introduce non-genetic fertility correlation in the forward in time process and to study its effects on the genealogies of individuals (or genes) samples. Since it is independent of the gene considered, this effect is uniform on the genome, even in diploid populations. For values of fertility correlation observed in human populations, we show that coalescence times are strongly but inhomogenously reduced and that the shape of gene genealogies is markedly unbalanced. Despite the fact that our simulations concern stationary populations, the former non-genetic effect is very similar to what has been described for populations of variable size such as populations passing through demographic bottleneck. However, additional strong tree imbalance due to non-genetic causes is reported here for the first time.
Alloploids, most of them hexaploid, from crosses between tetraploid wheat, Triticum carthlicum, and the perennial tetraploid Thinopyrum junceiforme were analysed for chromosome composition, stability and fertility using genomic in situ hybridization and meiotic analysis. The alloploids differed in their total number of chromosomes, 38-47 + telocentrics in "hexaploids" and 54 and 56 in "octoploids", and also in their number of Thinopyrum chromosomes (8-15). Translocations, mostly Robertsonian ones, were frequently found and intergenomic pairing was found to occur during meiosis. The stability was low which is reflected in the variability in chromosome number and in the number of univalents per PMC (2.3-4.0). The seedset was lower than in wheat, but high enough to secure a safe propagation and preservation. The alloploids are discussed in relation to widening the genetic variation of breadwheat and wheat breeding.