Phylogenetic Analysis Informed by Geological History Supports Multiple, Sequential Invasions of the Mediterranean Basin by the Angiosperm Family Araceae

Despite the remarkable species richness of the Mediterranean flora and its well-known geological history, few studies have investigated its temporal and spatial origins. Most importantly, the relative contribution of geological processes and long-distance dispersal to the composition of contemporary Mediterranean biotas remains largely unknown. We used phylogenetic analyses of sequences from six chloroplast DNA markers, Bayesian dating methods, and ancestral area reconstructions, in combination with paleogeographic, paleoclimatic, and ecological evidence, to elucidate the time frame and biogeographic events associated with the diversification of Araceae in the Mediterranean Basin. We focused on the origin of four species, Ambrosina bassii, Biarum dispar, Helicodiceros muscivorus, Arum pictum, subendemic or endemic to Corsica, Sardinia, and the Balearic Archipelago. The results support two main invasions of the Mediterranean Basin by the Araceae, one from an area connecting North America and Eurasia in the Late Cretaceous and one from the Anatolian microplate in western Asia during the Late Eocene, thus confirming the proposed heterogeneous origins of the Mediterranean flora. The subendemic Ambrosina bassii and Biarum dispar likely diverged sympatrically from their widespread Mediterranean sister clades in the Early-Middle Eocene and Early-Middle Miocene, respectively. Combined evidence corroborates a relictual origin for the endemic Helicodiceros muscivorus and Arum pictum, the former apparently representing the first documented case of vicariance driven by the initial splitting of the Hercynian belt in the Early Oligocene. A recurrent theme emerging from our analyses is that land connections and interruptions, caused by repeated cycles of marine transgressions-regressions between the Tethys and Paratethys, favored geodispersalist expansion of biotic ranges from western Asia into the western Mediterranean Basin and subsequent allopatric speciation at different points in time from the Late Eocene to the Late Oligocen

Gene drives: benefits, risks, and possible applications

Gene drives are genetic elements in sexually reproducing organisms that skew the pattern of inheritance of a given characteristic. They can be used to spread a characteristic that can alter or even reduce the numbers of individuals in wild populations of a certain species. As they spread by being inherited from one generation to the next, they could persist in populations long-term. The spreading property of gene drives could be a source of great potential in areas as diverse as the control of disease vectors, invasive species, agricultural pests and predators of endangered species. However, the same property may make containment challenging and therefore may also pose novel envi- ronmental risks. The evaluation, distribution of risks and benefits and the fact that gene drives may be seen as a particularly profound interference with nature further raises novel ethical considerations

Molecular Analysis, Cytogenetics and Fertility of Introgression Lines From Transgenic Wheat to Aegilops cylindrica Host

Natural hybridization and backcrossing between Aegilops cylindrica and Triticum aestivum can lead to introgression of wheat DNA into the wild species. Hybrids between Ae. cylindrica and wheat lines bearing herbicide resistance (bar), reporter (gus), fungal disease resistance (kp4), and increased insect tolerance (gna) transgenes were produced by pollination of emasculated Ae. cylindrica plants. F(1) hybrids were backcrossed to Ae. cylindrica under open-pollination conditions, and first backcrosses were selfed using pollen bags. Female fertility of F(1) ranged from 0.03 to 0.6%. Eighteen percent of the sown BC1s germinated and flowered. Chromosome numbers ranged from 30 to 84 and several of the plants bore wheat-specific sequence-characterized amplified regions (SCARs) and the bar gene. Self fertility in two BC1 plants was 0.16 and 5.21%, and the others were completely self-sterile. Among 19 BC1S1 individuals one plant was transgenic, had 43 chromosomes, contained the bar gene, and survived glufosinate treatments. The other BC1S1 plants had between 28 and 31 chromosomes, and several of them carried SCARs specific to wheat A and D genomes. Fertility of these plants was higher under open-pollination conditions than by selfing and did not necessarily correlate with even or euploid chromosome number. Some individuals having supernumerary wheat chromosomes recovered full fertility

Historical museum specimens reveal the loss of genetic and morphological diversity due to local extinctions in the endangered water chestnut Trapa natans L. (Lythraceae) from the southern Alpine lake area

Freshwater aquatic plants have increased extinction risks due to strong human pressure and the patchy nature of their habitats. However, their unclear population structure frequently hinders conservation planning. To investigate population subdivision and risks to long-term survival of such species, we combined genetic, morphometric and biogeographical approaches to the example of the endangered water chestnut Trapa natans (Lythraceae) from the southern Alpine lake area (Insubria). Amplified fragment length polymorphism (AFLP) of seven extant local stands revealed similar and intermediate levels of genetic diversity, of which c. 97% was partitioned within lakes. Thus, no signs of strong genetic drift and associated loss of genetic diversity were found, despite a reduction of c. 52% of local populations since the early 19th century. Nuclear ribosomal sequences (ITS1-5.8S rRNA-ITS2) combined with a morphometric study of nuts (based on fresh and historical museum material) revealed the presence of two genetically and morphologically slightly distinct lineages, one of which went extinct during the 20th century after a prolonged period of hyper-eutrophication. Taken together, our results indicate the current presence of one large Insubric Trapa population. To prevent genetic risks to survival associated with small population size and increasing fragmentation due to past extinctions, freshwater managers should preserve the large census sizes still present in many Insubric lakes and reduce eutrophication

Historical museum specimens reveal the loss of genetic and morphological diversity due to local extinctions in the endangered water chestnut Trapa natans L. (Lythraceae) from the southern Alpine lake area

Freshwater aquatic plants have increased extinction risks due to strong human pressure and the patchy nature of their habitats. However, their unclear population structure frequently hinders conservation planning. To investigate population subdivision and risks to long-term survival of such species, we combined genetic, morphometric and biogeographical approaches to the example of the endangered water chestnut Trapa natans (Lythraceae) from the southern Alpine lake area (Insubria). Amplified fragment length polymorphism (AFLP) of seven extant local stands revealed similar and intermediate levels of genetic diversity, of which c. 97% was partitioned within lakes. Thus, no signs of strong genetic drift and associated loss of genetic diversity were found, despite a reduction of c. 52% of local populations since the early 19th century. Nuclear ribosomal sequences (ITS1-5.8S rRNA-ITS2) combined with a morphometric study of nuts (based on fresh and historical museum material) revealed the presence of two genetically and morphologically slightly distinct lineages, one of which went extinct during the 20th century after a prolonged period of hyper-eutrophication. Taken together, our results indicate the current presence of one large Insubric Trapa population. To prevent genetic risks to survival associated with small population size and increasing fragmentation due to past extinctions, freshwater managers should preserve the large census sizes still present in many Insubric lakes and reduce eutrophication

Le forçage génétique ::bénéfices, risques et applications possibles

Les cassettes de forçage génétique ou guidage génétique (gene drives) sont des éléments génétiques d’organismes sexués qui modifient l’hérédité d’une caractéristique souhaitée. On peut s’en servir pour répandre un caractère pour modifier des individus ou bien pour réduire leur nombre dans des populations sauvages d’une espèce donnée. Comme ils se propagent de génération en génération par hérédité, les gene drives pourraient persister durablement dans les populations. Leur capacité de propagation peut représenter une formidable source de possibilités pour des domaines tels que le contrôle des vecteurs de maladies, des espèces invasives, des ravageurs des cultures et des prédateurs d’espèces menacées. Cette même caractéristique peut cependant s’avérer difficile à confiner et donc générer de nouveaux risques environnementaux. L’évaluation, la répartition des risques et des bénéfices et le fait que les gene drives peuvent être considérés comme une intervention particulièrement profonde sur la nature soulèvent de nouvelles considérations d’ordre éthique.Gene drives are genetic elements that skew the pattern of inheritance of a given characteristic in sexually reproducing organisms. They can be used to spread a characteristic that can alter or even reduce the numbers of individuals in wild populations of a certain species. As they spread by being inherited from one generation to the next, they could persist in populations long-term. The spreading property of gene drives could be a source of great potential in areas as diverse as the control of disease vectors, invasive species, agricultural pests and predators of endangered species. However, the same property may make containment challenging and therefore may also pose novel environmental risks. The evaluation, distribution of risks and benefits and the fact that gene drives may be seen as a particularly profound interference with nature raises further novel ethical considerations.Gene Drives sind genetische Elemente, welche die Vererbungsrate eines bestimmten Merkmals bei sich sexuell fortpflanzenden Organismen erhöhen. Sie können verwendet werden, um eine Eigenschaft in freilebenden Populationen zu verbreiten und diese dadurch zu verändern oder zu reduzieren. Da sich Gene Drives verbreiten, indem sie von einer Generation zur nächsten vererbt werden, könnten sie in Populationen langfristig bestehen bleiben. Die Fähigkeit von Gene Drives sich zu verbreiten, könnte grosses Potenzial für unterschiedlichste Anwendungsfelder bieten, etwa wenn es darum geht, Krankheitsüberträger, invasive Arten, landwirtschaftliche Schädlinge und Fressfeinde seltener Arten zu bekämpfen. Allerdings kann der kontrollierte Umgang mit Gene Drives eine Herausforderung darstellen, sodass diese möglicherweise neue Umweltrisiken mit sich bringen würden. Die Bewertung, die Verteilung von Risiken und Nutzen sowie die Tatsache, dass Gene Drives als besonders tiefgreifender Eingriff in die Natur angesehen werden können, werfen neue ethische Fragestellungen auf