Tagged: genetic drift


AoBP special issue announcement: Population differentiation in plants

Plant populations continually change over space and time. Many factors contribute to this differentiation with some resulting in evolutionary change. Unravelling the relative importance of ecological and genetic components of population differentiation is of paramount relevance to understand the future of plant biodiversity in a rapidly changing world. It is also critical that we determinethe pace and intensity with which differentiation is taking place. AoBP recently sponsored the ‘Evolutionary Ecology in Terrestrial, Aquatic Marine and Environments’ session of the SIBECOL meeting in Barcelona, Spain. In this session, the theoretical background of population differentiation was discussed in depth by Mohamed Abdelaziz, Antonio...

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Kleinia neriifolia

How repeatable is microevolution on islands?

Archipelagos provide a valuable framework for investigating phenotypic evolution under different levels of geographical isolation. García-Verdugo et al. analysed two co-distributed, widespread plant lineages to examine if incipient island differentiation follows parallel patterns of variation in traits related to dispersal and colonization. The authors sampled twenty-one populations of two anemochorous Canarian endemics, Kleinia neriifolia and Periploca laevigata, to represent mainland congeners and two contrasting exposures across all the main islands. Leaf size, seed size and dispersability (estimated as diaspore terminal velocity) were characterized in each population. For comparison, dispersability was also measured in four additional anemochorous island species. Plastid DNA...

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Iris lutescens

Spatial distribution of genetic variation in the flower colour polymorphic Iris lutescens

Flower colour polymorphism in plants had been used as a classic model for understanding the importance of neutral processes versus natural selection in population differentiation. Iris lutescens (Iridaceae) is a widespread species in the northern Mediterranean basin, which shows a stable and striking purple–yellow flower colour polymorphism. Using an extensive sampling over the distribution range of the species, Wang et al. provide evidence that genetic drift contributed to monomorphism in Spain, while gene flow between adjacent populations seems to be an important factor maintaining populations polymorphic in the South of France. Overall, neutral processes contribute to patterns of spatial variation...

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Lythrum salicaria

Style morph frequencies in tristylous Lythrum

A balance between stochastic processes and negative frequency-dependent selection largely determines style morph frequencies in heterostylous populations. Costa et al. investigate variation in morph frequencies at the southern European range limit of the tristylous, wetland species Lythrum salicaria. They find populations are predominantly trimorphic, but progressively smaller in size and with larger deviations from the predicted 1:1:1 equilibrium towards the drier southern edge of the distribution. This supports the hypothesis that deteriorating environmental conditions at range margins influence demographic features of populations, and demonstrates the resilience of floral trimorphism in the face of stressful conditions.

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Gene flow, drift and populations of Sardinian Aquilegia

Gene flow, drift and populations of Sardinian Aquilegia

The Mediterranean Basin is an important region for plant biodiversity, but there are relatively few studies of fine-scale genetic variation. Garrido et al. assess the spatial genetic structure of all known locations of the three Sardinian endemic species of Aquilegia (Ranunculaceae) and determine that genetic drift has been historically more influential than gene flow on population structure. They conclude that the spatial genetic structure found is not fully compatible with current taxonomic affiliations of Sardinian Aquilegia taxa.

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Genetic connectivity and evolution in Crepis

Genetic connectivity and evolution in Crepis

Islands play a central role in the study of plant evolution in the Mediterranean. Mayol et al. analyse the impact of varying patterns of habitat occupancy on genetic diversity and structure in Crepis triasii, an endemic plant from the eastern Balearic Islands, and find that genetic diversity is highly structured and positively correlated with population connectivity in the landscape. The results support the importance of restricted gene flow and drift as drivers of plant evolution in Mediterranean continental islands, and emphasize the importance of gene flow in preventing genetic erosion and maintaining the evolutionary potential of populations.

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