Phylogeny, Connectivity and Dispersal Patterns of the Giant Kelp Macrocystis (Phaeophyceae)

<p>Macrocystis represents the most widely distributed kelp genus, providing structure and energy for one of the most productive ecosystems on earth. Despite its ecological and economical importance, many aspects of its taxonomy, distribution and dispersal still remain unknown. Using different molecular markers I studied the taxonomy, phylogeography and dispersal patterns of Macrocystis. The analysis involves samples from different populations throughout the world. Using the DNA barcoding method I, confirmed previous suggestions that the genus must be considered as monospecific, M. pyrifera being the only species. The effects of historical and contemporary events on the haplotype distribution were determined by analyzing samples from the southeastern Pacific (SEP) using the atp8-S mitochondrial marker. The last glacial maximum as well as oceanographic anomalies (El Niño phenomena) may be important factors driving the genetic pattern along the SEP. The genetic structure in southern Chile was also analyzed in more detail, especially in the Chilean Fjords. Samples from attached and floating kelp individuals revealed that dispersal via kelp rafts is possible. Finally, a global analysis using COI sequences showed shared haplotypes along vast distances in the Northern and Southern hemispheres, recent dispersal and high gene flow can explain such genetic homogeneity. Additionally, microsatellite analysis confirmed that gene flow along the Southern Ocean is occurring over ecological time scales, where rafting of detached reproductive kelps seems to be facilitated by the Antarctic Circumpolar Current connecting populations in the Southern Hemisphere. This study has provided valuable genetic evidence to understand factors shaping the genetic structure of this important ecologically and economically species. It also contributes important knowledge for conservation and management strategies, especially in places where M. pyrifera has been harvested. In summary, the results of this study confirm previous suggestions of high gene flow among M. pyrifera populations at different scales. It also provides evidence suggesting that kelp rafts act as an important dispersal mechanism in this species, thus giving important information to understand the factors shaping the evolution of the largest seaweed on earth.</p>

Phylogeny, Connectivity and Dispersal Patterns of the Giant Kelp Macrocystis (Phaeophyceae)

<p>Macrocystis represents the most widely distributed kelp genus, providing structure and energy for one of the most productive ecosystems on earth. Despite its ecological and economical importance, many aspects of its taxonomy, distribution and dispersal still remain unknown. Using different molecular markers I studied the taxonomy, phylogeography and dispersal patterns of Macrocystis. The analysis involves samples from different populations throughout the world. Using the DNA barcoding method I, confirmed previous suggestions that the genus must be considered as monospecific, M. pyrifera being the only species. The effects of historical and contemporary events on the haplotype distribution were determined by analyzing samples from the southeastern Pacific (SEP) using the atp8-S mitochondrial marker. The last glacial maximum as well as oceanographic anomalies (El Niño phenomena) may be important factors driving the genetic pattern along the SEP. The genetic structure in southern Chile was also analyzed in more detail, especially in the Chilean Fjords. Samples from attached and floating kelp individuals revealed that dispersal via kelp rafts is possible. Finally, a global analysis using COI sequences showed shared haplotypes along vast distances in the Northern and Southern hemispheres, recent dispersal and high gene flow can explain such genetic homogeneity. Additionally, microsatellite analysis confirmed that gene flow along the Southern Ocean is occurring over ecological time scales, where rafting of detached reproductive kelps seems to be facilitated by the Antarctic Circumpolar Current connecting populations in the Southern Hemisphere. This study has provided valuable genetic evidence to understand factors shaping the genetic structure of this important ecologically and economically species. It also contributes important knowledge for conservation and management strategies, especially in places where M. pyrifera has been harvested. In summary, the results of this study confirm previous suggestions of high gene flow among M. pyrifera populations at different scales. It also provides evidence suggesting that kelp rafts act as an important dispersal mechanism in this species, thus giving important information to understand the factors shaping the evolution of the largest seaweed on earth.</p>

Grain Dispersal Mechanism In Cereals Arose From a Genome Duplication Followed By Changes in Spatial Expression of Genes Involved In Pollen Development

One of the most critical events in the process of cereal domestication was the loss of the natural mode of grain dispersal. Grain dispersal in barley is controlled by two major genes, Btr1 and Btr2, which affect the thickness of cell walls around the disarticulation zone. The barley genome also encodes Btr1-like and Btr2-like genes, which have been shown to be the ancestral copies. While Btr and Btr-like genes are non-redundant, the biological function of Btr-like genes is unknown. We explored the potential biological role of the Btr-like genes by surveying their expression profile across 212 publicly available transcriptome datasets representing diverse organs, developmental stages and stress conditions. We found that Btr1-like and Btr2-like are expressed exclusively in immature anther samples throughout Prophase I of meiosis within the meiocyte. The similar and restricted expression profile of these two genes suggests they are involved in a common biological function. Further analysis revealed 141 genes co-expressed with Btr1-like and 122 genes co-expressed with Btr2-like, with 105 genes in common, supporting Btr-like genes involvement in a shared molecular pathway. We hypothesize that the Btr-like genes play a crucial role in pollen development by facilitating the formation of the callose wall around the meiocyte or in the secretion of callase by the tapetum. Our data suggest that Btr genes retained an ancestral function in cell wall modification and gained a new role in grain dispersal due to changes in their spatial expression becoming spike specific after gene-duplication.

Quantifying the Role of Ground Beetles for the Dispersal of Fusarium and Alternaria Fungi in Agricultural Landscapes

The spread by arthropods (zoochory) is an essential dispersal mechanism for many microorganisms, like plant pathogens. Carabid beetles are very abundant and mobile ground-dwelling insects. However, their role in the dispersal of economically relevant phytopathogens, like Fusarium and Alternaria fungi is basically unknown. We quantified the total fungal, Fusarium, and Alternaria load of carabid species collected in the transition zones between small water bodies and wheat fields by screening (i) their body surface for fungal propagules with a culture-dependent method and (ii) their entire bodies for fungal DNA with a qPCR approach. The analysis of entire bodies detects fungal DNA in all carabid beetles but Alternaria DNA in 98% of them. We found that 74% of the carabids carried fungal propagules on the body surface, of which only half (49%) carried Fusarium propagules. We identified eight Fusarium and four Alternaria species on the body surface; F. culmorum was dominant. The fungal, Fusarium and Alternaria, load differed significantly between the carabid species and was positively affected by the body size and weight of the carabids. Carabid beetles reveal a remarkable potential to disseminate different fungi. Dispersal by ground-dwelling arthropods could affect the spatial-temporal patterns of plant disease and microorganisms in general.

THE UNPREDICTABLE EXPLOSIVE DISPERSAL MECHANISM OF A PRICKLY NEOTROPICAL Solanum (SOLANACEAE)

The mechanism of explosive dehiscence is rare in fruits in Solanum (Solanaceae), being reported for Solanum sect. Gonatotricum, a small non-aculeate group belonging to the Brevantherum clade. We tested empirically the presence of this strategy in populations of the closely related S. mellobarretoi and S. leptostachys, species belonging to the Leptostemonum clade, a group that comprises most aculeate species of the genus. Our results showed the occurrence of the explosive dehiscence in berries of S. mellobarretoi, but not in S. leptostachys, besides their phylogenetic and morphological similarities. We confirmed the homoplasic nature of the mechanism within the genus and highlight the importance of conducting empirical studies, contributing to reduce knowledge gaps on seed dispersal in the Neotropics.

Effects of meteorological conditions on the air quality in deep open - pit mines in Vietnam

Air quality in open - pit mines is the big concern relating to the occupational safety and healthy, as well as the surrounding environment. In the past years, management of the air quality in open - pit mines is challenge due to the limit of science and technology in the assessment of the effects of meteorological conditions and toxics in open - pit mines. Therefore, this study assessed the effects of meteorological conditions on the air quality in deep open - pit mines. The air velocity distribution and the dispersal mechanism of the air quality were evaluated at the Coc Sau open - pit coal mine (Vietnam) based on the measured and simulated datasets. Two fixed stations were set up in the ground to monitor the wind direction, wind speed and the temperature to evaluate the stable of the actual ozone layer based on the Pasquill ozone layer. The datasets were also used to analysis and 3D simulate to understand the air pollution mechanism in the Coc Sau open - pit coal mine. On the other hand, the change of the temperature in vertical was measured to determine the to determine the existence of a temperature inversion layer. It is considered as the main reason for the air quality reduction and the natural air circulation in deep open - pit mines. The findings indicated the existence of the temperature inversion layer and they are useful for proposing the artificial ventilation in deep open - pit mine, aiming to improve the air quality in open - pit mines. The 3D simulations also revealed that the high dust and gas concentrations in open - pit mines are due to the stable of the ozone layer.

No Effect of Selective Maturation on Fruit Traits for a Bird-Dispersed Species, Sambucus racemosa

Selective abortion, also called selective maturation, is a phenomenon wherein maternal plants selectively mature ovules that have the potential to grow into higher-quality fruits, such as those that contain more seeds. We hypothesized that the effects of selective maturation on fruit traits could be influenced by the dispersal mechanism. However, to date, limited studies have been conducted on selective maturation in bird-dispersed fruits. Unlike self- or wind-dispersed species, bird-dispersed species would not selectively mature fruits that contain more seeds because they are not preferred by birds. Here, we investigated the effect of selective abortion on the fruit traits of a bird-dispersed species, elderberry (Sambucus racemosa L. subsp. kamtschatica). We performed a flower-removal experiment. Half of the inflorescences on each individual tree were removed for the treatment group, whereas the control group was not manipulated. We found that the flower-removed trees showed higher fruit sets, suggesting the existence of resource limitation. The number of seeds per fruit did not increase by the experimental treatment. Additionally, the control individuals did not produce larger fruits. The lack of effects on fruit traits supported our hypothesis that the effect of selective maturation on fruit traits may differ among species with different dispersal mechanisms.

Pollination.

Pollination of flowers is the transfer of pollen grains (haploid male spores) from the anther (part of the androecium) to the stigma (part of the gynoecium) by biotic or abiotic factors (Sliwinska and Bewley, 2014). For seed and fruit production of agricultural crops the main pollinating agents are wind and insects (George, 2011). After a pollen grain is transferred to a receptive stigma, it absorbs water from the stigma surface and germinates. A pollen tube then grows down into the stigma, through the gynoecium and through the apical micropyle; from there it grows into an ovule in the ovary and double fertilisation then takes place. Two sperm are released into the embryo sac; one fertilises the ovule to produce a diploid zygote, and the other joins with two polar nuclei in the ovule to produce a triploid nucleus that will then develop into the nutrient-rich endosperm (Willmer, 2011). Pollen grain diameter is usually in the range 20-70 μm, and the surface structure and morphology varies considerably between plant species and dispersal mechanism (Wiltshire, 2010). Air temperature can have an effect on pollen formation and viability, with high temperatures potentially leading to sterile pollen (Bosland and Votava, 2012). Irradiated pollen grains are still able to germinate and produce pollen tubes that reach the ovule (Germana, 2012). Although they are unable to fertilise the egg cell, this process induces parthenogenesis and has been widely used to produce haploid fruits (Germana, 2012).

Martynia annua (tiger's claw).

Martynia annua is grown as an ornamental and medicinal herb. Originally native to Mexico, Central America and the Caribbean, its effective seed dispersal mechanism has helped it spread throughout tropical and subtropical regions of the world as a weed of pastures, disturbed sites, roadsides, moist thickets, riverbanks and floodplains. Currently, it is listed as invasive in Australia, New Caledonia, China, India, Indonesia, Malaysia and Cuba.

Phylogeography of Ryukyu insular cicadas: Extensive vicariance by island isolation vs accidental dispersal by super typhoon

Cicadas tend to be affected by vicariance reflecting poor mobility of nymphs underground and weak flying ability of adults. However, modern collection records of invasive cicada, combined with records of typhoon tracks, and newly obtained phylogeographic data suggest long distance, relatively instantaneous, dispersal of some vicariantly speciated cicadas. We address the importance of this typhoon dispersal mechanism applied to representative species of east Asian endemic cicadas of Cryptotympana, Mogannia, Euterpnosia and Meimuna. We combine BEAST-dated phylogenic and haplotype network analyses, modern collection data of non-native cicadas available in reports of the Japanese insect associations, modern typhoon records by Japan Meteorological Agency, and our own Quaternary geological constriction data. In conclusion, although Ryukyu endemic cicadas were vicariantly speciated, endemic cicadas on some islands were accidentally dispersed long distances to another island by typhoons, particularly those associated with super typhoons generated since 1.55 Ma.