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Summary: Evolutionary radiation, a pivotal aspect of macroevolution, offers valuable insights into evolutionary processes. The genus Pinus is the largest genus in conifers with c. 90% of the extant species emerged in the Miocene, which signifies a case of rapid diversification. Despite this remarkable history, our understanding of the mechanisms driving radiation within this expansive genus has remained limited.Using exome capture sequencing and a fossil‐calibrated phylogeny, we investigated the divergence history, niche diversification, and introgression among 13 closely related Eurasian species spanning climate zones from the tropics to the boreal Arctic.We detected complex introgression among lineages in subsection Pinus at all stages of the phylogeny. Despite this widespread gene exchange, each species maintained its genetic identity and showed clear niche differentiation. Demographic analysis unveiled distinct population histories among these species, which further influenced the nucleotide diversity and efficacy of purifying and positive selection in each species.Our findings suggest that radiation in the Eurasian pines was likely fueled by interspecific recombination and further reinforced by their adaptation to distinct environments. Our study highlights the constraints and opportunities for evolutionary change, and the expectations of future adaptation in response to environmental changes in different lineages. [ABSTRACT FROM AUTHOR]

Hybridization is a process of great importance in the ecology and evolution of plants. However, identifying hybrids is not an easy task, especially in cases of sympatry. Such cases are the Abies taxa in Greece; Silver fir (A. alba), Greek fir (A. cephalonica) and King Boris fir (A. × borisii-regis). The latter has been characterized as a hybrid between the first two species as its morphological traits are either a combination of the parental ones or intermediate. Besides the morphological traits, A. × borisii-regis has so far been identified only at the population level, with biochemical and DNA markers. Here, we describe the identification of A. × borisii-regis at the individual level by employing a species-specific marker in the cpDNA and another in mtDNA, taking advantage of their uniparental inheritance mode from the paternal and the maternal parent, respectively. In addition, based on these markers, essential information emerges on the distribution and the mtDNA diversity of the Abies taxa in Greece. [ABSTRACT FROM AUTHOR]

Fertilization in angiosperms involves the germination of pollen on the stigma, followed by the extrusion of a pollen tube that elongates through the style and delivers two sperm cells to the embryo sac. Sexual selection could occur throughout this process when male gametophytes compete for fertilization. The strength of sexual selection during pollen competition should be affected by the number of genotypes deposited on the stigma. As increased self-fertilization reduces the number of mating partners, and the genetic diversity and heterozygosity of populations, it should thereby reduce the intensity of sexual selection during pollen competition. Despite the prevalence of mating system shifts, few studies have directly compared the molecular signatures of sexual selection during pollen competition in populations with different mating systems. Here we analyzed whole-genome sequences from natural populations of Arabis alpina , a species showing mating system variation across its distribution, to test whether shifts from cross- to self-fertilization result in molecular signatures consistent with sexual selection on genes involved in pollen competition. We found evidence for efficient purifying selection on genes expressed in vegetative pollen, and overall weaker selection on sperm-expressed genes. This pattern was robust when controlling for gene expression level and specificity. In agreement with the expectation that sexual selection intensifies under cross-fertilization, we found that the efficacy of purifying selection on male gametophyte-expressed genes was significantly stronger in genetically more diverse and outbred populations. Our results show that intra-sexual competition shapes the evolution of pollen-expressed genes, and that its strength fades with increasing self-fertilization rates. [ABSTRACT FROM AUTHOR]

Broad-scale plastid (chloroplast) DNA studies of beech ( Fagus sylvatica) populations suggest the existence of glacial refugia and introgression zones in south-eastern Europe. We choose a possible refugium of beech in northern Greece, Mt. Paggeo, which hosts a private plastid haplotype for beech, to conduct a fine-scale genetic study. We attempt to confirm or reject the hypothesis of the existence of a small-scale refugium and to gain an understanding of the ecological and topographical factors affecting the spatial distribution of plastid haplotypes in the area. Our results reveal a high haplotype diversity on Mt. Paggeo, but the overall distribution of haplotypes shows no significant correlation with the ecological characteristics of the beech forests. However, the private haplotype is found at high frequencies in beech forests located in or near ravines, having a high spatial overlap with a relict vegetation type occurring in ecological conditions found mainly in ravines. This result emphasizes the importance of topography in the existence of glacial refugia in the wider area. Furthermore, haplotypes originating from two more widespread beech lineages in Greece are found on Mt. Paggeo, indicating a possible mixing of populations originating from a local refugium with populations from remote refugia that possibly migrated into the area after the last glaciation. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174, 516-528. [ABSTRACT FROM AUTHOR]