Olives have a long and complex history. The origins of the Mediterranean cultivated olive (Olea europaea subsp. europaea) are hotly debated, but it is usually accepted that its domestication started in the Levant based on archaeological, historical and molecular evidence. Multiple local selections of cultivars has been suggested by genetic analyses, followed by secondary diversification of the crop followed the oleiculture diffusion over the whole Mediterranean basin. The contribution of western wild olives in this diversification process remains poorly understood.
A recent paper in Annals of Botany describes patterns of genetic differentiation in Mediterranean and Saharan olives, and tests for admixture between these taxa. Based on the results, the human-meditated diffusion of the oleiculture over the Mediterranean basin and the contribution of O. europaea subsp. laperrinei to the cultivated olive diversification are discussed. Although its genetic contribution is limited, it is clear from this work that Laperrine’s olive has been involved in the diversification of cultivated olives.
Besnard G., El Bakkali A., Haouane H., Baali-Cherif D., Moukhli A. & Khadari B. (2013). Population genetics of Mediterranean and Saharan olives: geographic patterns of differentiation and evidence for early generations of admixture, Annals of Botany, 112 (7) 1293-1302 DOI: 10.1093/aob/mct196
Individual mating patterns in mixed oak stands
Individual variation in mating patterns may have significant implications for persistence and adaptation of plant populations, but field data generally focus on population averages. Using a Bayesian approach, Chybicki and Burczyk examine the extent of individual variation of several components of mating patterns in a mixed stand of Quercus robur and Q. petraea. They find that there is a great variation in intra- and inter-specific individual mating preferences, individual pollen immigration rates and heterogeneity of immigrating pollen. They show that trees can mate assortatively, with little respect to spatial proximity. Such selective mating may be a result of variable compatibility among trees due to genetic and/or environmental factors.
Single-copy nuclear genes for palm phylogenetics
Molecular phylogenetic studies of palms (Arecaceae) have not yet provided a fully resolved phylogeny of the family. Ludeña et al. test the value of AGAMOUS 1 and PHYTOCHROME B genes as new nuclear markers to improve phylogenetic resolution in the family, using the subtribe Bactridinae as a case study. The results provide new insights into the intergeneric relationships within Bactridinae and the intrageneric structure of Astrocaryum, and the existence of a monophyletic group sister to Astrocayum, corresponding to the debated genus Hexopetion, is supported. The new markers thus provide additional phylogenetic information within the palm family, and should prove useful in combination with other genes to improve the resolution of palm phylogenies.
Diversification in Hawaiian Dubautia laxa
The Hawaiian silversword alliance (Asteraceae) is one the best examples of a plant adaptive radiation, exhibiting extensive morphological and ecological diversity. Using subspecies of Dubautia laxa as an example, McGlaughlin & Friar show that genetic data demonstrates that members of the species have diverged primarily due to geographic isolation both within and among islands. Despite distinct morphological and ecological traits, subspecies that are distributed allopatrically are determined to have not diverged genetically.
How far can a gene disperse? Historical and contemporary gene dispersal can be estimated from spatial genetic structure and paternity analysis, and Rong et al. (pp. 285–296) find that an estimate of gene flow in Daucus carota ssp. carota based on contemporary pollen dispersal is much larger than an estimate of historical flow. The results have implications for the ease with which transgene flow might occur from cultivated GM carrots to wild carrot populations.