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Effective monitoring of non-indigenous seaweeds and combatting their effects relies on a solid confirmation of the non-indigenous status of the respective species. We critically analysed the status of presumed non-indigenous seaweed species reported from the Mediterranean Sea, the Northeast Atlantic Ocean and Macaronesia, resulting in a list of 140 species whose non-indigenous nature is undisputed. For an additional 87 species it is unclear if they are native or non-indigenous (cryptogenic species) or their identity requires confirmation (data deficient species). We discuss the factors underlying both taxonomic and biogeographic uncertainties and outline recommendations to reduce uncertainty about the non-indigenous status of seaweeds. Our dataset consisted of over 19,000 distribution records, half of which can be attributed to only five species (Sargassum muticum, Bonnemaisonia hamifera, Asparagopsis armata, Caulerpa cylindracea and Colpomenia peregrina), while 56 species (40%) are recorded no more than once or twice. In addition, our analyses revealed considerable variation in the diversity of non-indigenous species between the geographic regions. The Eastern Mediterranean Sea is home to the largest fraction of non-indigenous seaweed species, the majority of which have a Red Sea or Indo-Pacific origin and have entered the Mediterranean Sea mostly via the Suez Canal. Non-indigenous seaweeds with native ranges situated in the Northwest Pacific make up a large fraction of the total in the Western Mediterranean Sea, Lusitania and Northern Europe, followed by non-indigenous species with a presumed Australasian origin. Uncertainty remains, however, regarding the native range of a substantial fraction of non-indigenous seaweeds in the study area. In so far as analyses of first detections can serve as a proxy for the introduction rate of non-indigenous seaweeds, these do not reveal a decrease in the introduction rate, indicating that the current measures and policies are insufficient to battle the introduction and spread of non-indigenous species in the study area. Non-indigenous seaweed species in the Northeast Atlantic Ocean, the Mediterranean Sea and Macaronesia are critically reanalysed. > 19,000 distribution records revealed considerable variation in diversity of non-indigenous seaweed species in the study area. Taxonomic and biogeographic uncertainties hamper a critical evaluation of the non-indigenous status of many seaweed species. [ABSTRACT FROM AUTHOR]

Polyploidy, resulting from whole‐genome duplication (WGD), is ubiquitous in nature and reportedly associated with extreme environments and biological invasions. However, WGD usually comes with great costs, raising questions about the establishment chance of newly formed polyploids. The surprisingly high number of polyploid and mixed‐ploidy species observed in nature may be a consequence of their continuous emergence or may reflect stable polyploid persistence and even coexistence with the ancestral ploidy under certain circumstances. However, empirical studies on contemporary polyploid establishment often neglect the cost–benefit balances of polyploid characteristics, tradeoffs between phenotypic characteristics, intercytotype interactions, recurrent polyploid formation, and stochastic processes. Here, we advocate for considering population‐level success, combining the aforementioned factors that affect polyploid establishment and long‐term coexistence with their ancestors. We approach the paradox of polyploid establishment despite high costs from a modern coexistence theory perspective and give an overview of the diversity of mechanisms and their timing that may potentially enable stable rather than transient persistence. [ABSTRACT FROM AUTHOR]

In this study we explore the introduction of the brown alga Dictyota acutiloba in the Mediterranean Sea and provide a substantive update on the geographic distribution of this species, which was long thought to be confined to the Pacific Ocean. A critical assessment of published distribution records and additional identifications based on cox1, psbA and rbcL genetic markers confirm the presence of D. acutiloba at a number of locations in the Indo-Pacific as well as three locations along the Israeli coastline in the south-eastern Mediterranean Sea. The close genetic affinity between introduced specimens and those from a population in Hurghada (Red Sea) strongly suggests an introduction via the Suez Canal. The occurrence of D. acutiloba in these regions is further supported by predictions made by correlative ecological niche models (ENMs), which show high suitability values in the northern Red Sea and the Levantine Basin. In contrast, environmental conditions in the western Mediterranean and parts of the north-eastern Mediterranean are currently less favourable, as evidenced by the lower predicted probability of occurrence. Under future scenarios, the suitability of these regions increases. The further spread of D. acutiloba in the eastern Mediterranean seems imminent, and the species may even extend its range to the western Mediterranean Sea, depending on the climate change scenario considered. While D. acutiloba can be relatively easily distinguished from the majority of Mediterranean Dictyota species, it remains difficult to differentiate this species from narrow growth forms of D. dichotoma. Therefore, we recommend the use of molecular markers such as cox1, psbA and rbcL, to unequivocally identify this species and monitor its further spread. The geographic distribution of Dictyota acutiloba was substantially updated. D. acutiloba was probably introduced into the Mediterranean Sea via the Suez Canal. The Mediterranean Sea will become increasingly suitable for this species. [ABSTRACT FROM AUTHOR]

The immediate effects of plant polyploidization are well characterized and it is generally accepted that these morphological, physiological, developmental, and phenological changes contribute to polyploid establishment. Studies on the environmental dependence of the immediate effects of whole-genome duplication (WGD) are, however, scarce but suggest that these immediate effects are altered by stressful conditions. As polyploid establishment seems to be associated with environmental disturbance, the relationship between ploidy-induced phenotypical changes and environmental conditions is highly relevant. Here, we use a common garden experiment on the greater duckweed Spirodela polyrhiza to test whether the immediate effects of WGD can facilitate the establishment of tetraploid duckweed along gradients of two environmental stressors. Because successful polyploid establishment often depends on recurrent polyploidization events, we include four genetically diverse strains and assess whether these immediate effects are strain-specific. We find evidence that WGD can indeed confer a fitness advantage under stressful conditions and that the environment affects ploidy-induced changes in fitness and trait reaction norms in a strain-specific way. [ABSTRACT FROM AUTHOR]

Here, we report for the first time the presence of Dictyota cyanoloma in southern California. Dictyota cyanoloma is conspicuous in harbors and bays by its distinctive bright blue‐iridescent margins. This species was originally described from Europe, but subsequent studies have revealed that it represented an introduction from Australia. The current distribution of D. cyanoloma comprises southern Australia and the North East Atlantic, including the Mediterranean Sea and the Macaronesian islands. The presence of D. cyanoloma in southern California is supported by molecular cox1 and psbA gene sequences. A reconstruction of the invasive history based on nine polymorphic microsatellite markers reveals a close affinity of the Californian specimens with European populations. Dictyota cyanoloma in the United States appears to be (so far) restricted to the Californian coast from San Diego Bay in the south to Santa Catalina Island and Long Beach Harbor in the north. A correlative species distribution model suggests gradually declining habitat suitability north of the Southern Californian Bight and high suitability in Baja California, including the Gulf of California. Finally, its widespread abundance in bays and harbors suggests shipping is a likely transport mechanism. [ABSTRACT FROM AUTHOR]

The spatial configuration and size of patches influence metapopulation dynamics by altering colonisation–extinction dynamics and local density dependency. This spatial forcing as determined by the metapopulation typology then imposes strong selection pressures on life‐history traits, which will in turn feed back on the ecological metapopulation dynamics. Given the relevance of metapopulation persistence for biological conservation, and the potential rescuing role of evolution, a firm understanding of the relevance of these eco‐evolutionary processes is essential.We here follow a systems' modelling approach to quantify the importance of spatial forcing and experimentally observed life‐history evolution for metapopulation demography as quantified by (meta)population size and variability. We therefore developed an individual‐based model matching an earlier experimental evolution with spider mites to perform virtual translocation and invasion experiments that would have been otherwise impossible to conduct.We show that (a) metapopulation demography is more affected by spatial forcing than by life‐history evolution, but that life‐history evolution contributes substantially to changes in local‐ and especially metapopulation‐level population sizes, (b) extinction rates are minimised by evolution in classical metapopulations, and (c) evolution is optimising individual performance in metapopulations when considering the importance of more cryptic stress resistance evolution.Ecological systems' modelling opens up a promising avenue to quantify the importance of eco‐evolutionary feedbacks in spatially structured populations. Metapopulation sizes are especially impacted by evolution, but its variability is mainly determined by the spatial forcing.Eco‐evolutionary dynamics can increase the persistence of classical metapopulations. Conservation of genetic variation and, hence, adaptive potential is thus not only essential in the face of environmental change; it also generates putative rescuing feedbacks that impact metapopulation persistence. In this paper, the authors follow a system's modelling approach to disentangle the role of metapopulation structure relative to evolution for metapopulation performance. They provide evidence that metapopulation‐level selection maximises individual performance and, more importantly, that evolved changes in life histories following changes in metapopulation structure have the potential to feed back on metapopulation dynamics, especially on local and metapopulation sizes. [ABSTRACT FROM AUTHOR]

In this chapter, we present the use of Chlamydomonas reinhardtii in experiments designed to study the evolutionary impacts of whole genome duplication. We shortly introduce the algal species and depict why it is an excellent model for experimental evolution. Subsequently, we discuss the most relevant steps and methods in the design of a ploidy-related Chlamydomonas experiment. These steps include strain selection, ploidy determination, different methods of making diplo- and polyploid Chlamydomonas cells, replication, culturing conditions, preservation, and the ways to quantify phenotypic and genotypic change., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

In this chapter, we present the use of Spirodela polyrhiza in experiments designed to study the evolutionary impact of whole-genome duplication (WGD). We shortly introduce this duckweed species and explain why it is a suitable model for experimental evolution. Subsequently, we discuss the most relevant steps and methods in the design of a ploidy-related duckweed experiment. These steps include strain selection, ploidy determination, different methods of making polyploid duckweeds, replication, culturing conditions, preservation, and the ways to quantify phenotypic and transcriptomic change., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)