Tagged: genetic diversity

The oriental plane tree

Genetic diversity in relict populations of the oriental plane tree

The distribution of plant species around the Mediterranean basin is a product of the influence of both geographical barriers and of climatic changes experienced during the Tertiary, with the transition from a warm to a cool period. Several species, once largely distributed across the Northern Hemisphere, retracted to refugial areas in southern Europe where they are described as Tertiary relicts. The oriental plane tree (Platanus orientalis) is a typical representative of Tertiary flora in southwest Eurasia; distributed along river courses from the central Mediterranean to the Caucasus and India. The southern part of the Italian peninsula and Sicily represent the...

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East African bananas

East African traditional bananas: the resources of an understated diversity

Banana cultivation is a long tradition for numerous communities in East Africa, growing particularly the robust diploid ‘Mchare’ variety in the Kilimanjaro and the triploid ‘Mutika’ in the Great Lakes region. Since the 1970s, drastic yield declines due to soil degradation and emergent pests and diseases, has led to the disaffection by farmers for traditional varieties. Improved varieties are needed requiring elucidating the genetic origins of these unique bananas. Perrier et al. show that ‘Mchare’, ‘Mutika’ and other related East African diploids and triploids are connected within the same genetic complex whose primary centre is in Southeast Asia. They also...

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Arabidopsis

Adaptation of ecological strategies to climate within species

In Grime’s C-S-R strategy model, plant ecological strategies vary between ruderals (R), stress-tolerators (S) and competitors (C). These variations are assumed to reflect adaptation of species to the environment, although the relationships with environmental factors such as climate remain debated. Moreover, adaptive processes such as selection and diversification need to be tested within species. Vasseur et al. show that C-S-R strategies diversify with climate between lineages of Arabidopsis thaliana. Intraspecific variations notably result from a selection gradient on stress-tolerance and ruderality with latitude. This highlights the potential of merging functional ecology and biogeography with evolutionary genomics to understand plant adaptation...

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Collection locations of Isatis tinctoria in Eurasia.

Geographic population structure in an outcrossing plant invasion after centuries of cultivation and recent founding events

Population structure and genetic diversity of plant invasions are the result of evolutionary processes such as natural selection, drift and founding events. Some invasions are also molded by specific human activities such as selection for cultivars and intentional introduction of desired phenotypes, which can lead to low genetic diversity in the resulting invasion. Dyer’s woad (Isatis tinctoria; Brassicaceae) has been used as a dye source for at least eight centuries in Eurasia. It was introduced to the eastern USA in the 1600s and is now considered invasive in the western USA. A recent study by Gaskin et al. published in...

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Genetic evaluation of an endemic plant from Patagonia

Oxalis laciniata is endemic to the Patagonia region of South America, inhabiting high mountains and steppe and even growing on the coast. In a recent study published in AoB PLANTS by López and Bonasora, the marked polymorphism in this species led the authors to test whether its genetic variability would explain both its morphological variability and its adaptability to different ecological niches. Based on molecular analysis, the authors detected non-random organization of genetic variability. They proposed two refugia and were able to estimate the diversification centre, which coincided with the centre of the distribution. Distribution modelling suggested the possibility of...

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Arachnitis uniflora

Genetic diversity and evolution of arbuscular mycorrhizal fungi in Arachnitis uniflora

Arachnitis uniflora is a mycoheterotrophic plant that obtains nutrients via arbuscular mycorrhizal fungi of neighbouring autrotrophic plants. Some mycoheterotrophic plants have the ability to associate with more than one fungal family. Renny et al. identified fungal taxa associated with A. uniflora over 25 sites across its geographic range. High genetic diversity was associated with temperature, rainfall and soil features. Molecular tools reveal phylogenetic and phylogeographic fungal structures, uncovering associations with three Glomeromycotan families, with Glomeraceae emerging as the dominant symbiont. The fungal lineage originated around the Upper Cretaceous epoch, diversifying at the Miocene. The two families not previously found in...

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Study stands of Pinus halepensis in the Eastern Iberian Peninsula belong to different ecoregions.

Frequent wildfires modify genetic structure in Pinus halepensis

The recurrence of wildfires is predicted to increase due to global climate change. Budde et al. examine the population genetic effects of frequent fires in natural stands of the fire-adapted Mediterranean tree Pinus halepensis (Pinaceae) and find that genetic diversity was preserved despite frequent fires. However, nearby trees were more closely related than in control stands, a likely consequence of clumped recruitment after fire. Some genetic markers displayed evidence of selection between or within stands. More frequent wildfires can act as selective drivers, altering recruitment in P. halepensis and plants with similar life history traits.

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Schematic representation the demographic history scenarios simulated for the 23 populations of Eugenia dysenterica sampled in the Cerrado biome, and their geographical representation as predicted by ecological niche models (ENMs

Origin of distribution and genetic diversity of a savanna species

Cyclic glaciations were frequent throughout the Quaternary and this affected species distribution and population differentiation worldwide. Combining ecological niche modelling and phylogeographical analysis, this study by Lima et al. suggests that the distribution of Eugenia dysenterica (Myrtaceae) radiated outwards from the central region of the Cerrado biome, and that its genetic diversity pattern is due to climatic oscillations that occurred during the Quaternary. These findings are important for understanding the historical processes that leads to the current distribution of species.

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Sampling plots of Mikania micrantha in Guangdong Province, South China.

From South America to Shenzhen, China; road trip of an invasive weed

The South American weed Mikania micrantha has spread rapidly across Southern China since its introduction to the Shenzhen region in 1984. Geng et al. used SSR markers to investigate and map genetic diversification of this weed along highways. The results show a relatively low level of genetic differentiation, a lack of clear geographic genetic structure and strong gene flow between populations. The long-distance dispersal of seeds associated with vehicular transportation on highways may have provided corridors for the spread of M. micrantha in Southern China, thereby shaping genetic variation.

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toadflax Linaria cavanillesii

Mixed mating after the loss of self-incompatibility in a long-living perennial herb

Flowering plants display an extensive range of adaptive floral forms, which are often correlated with their mating systems. The maintenance of contrasting strategies such as those adopted by obligate outcrossers compared to populations that have evolved a selfing system is one of the most studied topics in reproductive evolution. Voillemot and Pannell study variation in mating systems in Spanish toadflax Linaria cavanillesii, a long-lived perennial species. Some unexpected features are reported, such as an absence of shift in flower morphology in the self-compatible population, together with the maintenance of outcrossing despite no apparent inbreeding depression.

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Historical refugia and origins of genetic diversity in a Neotropical savanna tree species

Souza et al. investigate the role of Pleistocene climate changes in driving the geographic distribution and genetic diversity of Dimorphandra mollis, a tree species endemic to the Cerrado, the largest Neotropical savanna and a biodiversity hotspot. Statistical phylogeography, coalescent analyses and ecological niche modelling (ENM) revealed an extensive site of historical refugium across Central Brazil. A spatial cline of genetic diversity decreasing outwards from the centre of this historically stable area was found. The discovery of this refugium could inform the implementation of conservation measures to safeguard the evolutionary potential of the species in face of the threats posed by...

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