Remote Oceanic Islands Research Articles

Oceanic islands act as drivers for the genetic diversity of marine species: Cardita calyculata (Linnaeus, 1758) in the NE Atlantic as a case-study

Geographic distribution, as well as evolutionary and biogeographic processes and patterns of marine invertebrate benthic species are strongly shaped by dispersal ability during the life cycle. Remote oceanic islands lie at the brink of complex biotic and abiotic interactions which have significantly influenced the biodiversity patterns we see today. The interaction between geological environmental change and taxon-specific dispersal modes can influence species evolutionary patterns, eventually delimiting species-specific biogeographic regions. In this study, we compare the population genetic patterns of the marine bivalve Cardita calyculata in the northeast Atlantic, discussing the role of Macaronesian islands during past climatic cycles. The genetic structure and diversity patterns were outlined based on SSR-GBAS loci of 165 individuals and on the mitochondrial COI marker of 22 individuals from the Canary Islands, Madeira, Azores and the Mediterranean. The highly structured genetic pattern found among regions and within archipelagos suggests the central role of oceanic islands in promoting the divergence of the species in both the NE Atlantic and the Mediterranean. The high degree of divergence in the COI dataset (> 7%) suggests the existence of potential cryptic speciation that needs to be further explored with a more comprehensive sampling. Such patterns are only congruent with a scenario where C. calyculata populations were maintained during glacial/interglacial cycles, supporting the role of the studied archipelagos as drivers of diversity for marine biota. We stress the importance of developing studies for species with various life history and dispersal modes. In such a way, a more profound understanding of the biogeographic and evolutionary significance of oceanic islands can catalyse directed conservation efforts, especially in the context of the ongoing climate crisis.

Three new species of Amphipoda (Crustacea: Peracarida) from the remote oceanic island of Trindade, off the coast of south-eastern Brazil

ABSTRACT Trindade is a volcanic remote island isolated some 1200 km from the nearest continental landmass. While knowledge of the island’s diversity of crustacean decapod fauna has been notably broadened by extensive investigations, knowledge about its amphipod fauna is still poor. During a 12-year survey (2012–2024) a wealth of amphipod material was obtained in Trindade from various sublittoral habitats at water depths of less than 30 m. Here, we report on three new species of the genera Colomastix Grube, 1861, Pariphinotus Kunkel, 1910 and Eusiroides Stebbing, 1888. Additionally, identification keys to the world species of Eusiroides and Pariphinotus, and to the Brazilian species of Colomastix are provided. http://www.zoobank.org/urn:lsid:zoobank.org:pub:B17266F0-B78E-4768-8FB2-D91BA5F748CA

Phthalates and fatty acid markers in free-ranging cetaceans from an insular oceanic region: Ecological niches as drivers of contamination

Plastic additives, such as phthalates, are ubiquitous contaminants that can have detrimental impacts on marine organisms and overall ecosystems' health. Valuable information about the status and resilience of marine ecosystems can be obtained through the monitoring of key indicator species, such as cetaceans. In this study, fatty acid profiles and phthalates were examined in blubber biopsies of free-ranging individuals from two delphinid species (short-finned pilot whale – Globicephala macrorhynchus, n = 45; common bottlenose dolphin – Tursiops truncatus, n = 39) off Madeira Island (NE Atlantic). This investigation aimed to explore the relations between trophic niches (epipelagic vs. mesopelagic), contamination levels, and the health status of individuals within different ecological and biological groups (defined by species, residency patterns and sex). Multivariate analysis of selected dietary fatty acids revealed a clear niche segregation between the two species. Di-n-butylphthalate (DBP), diethyl phthalate (DEP), and bis(2-ethylhexyl) phthalate (DEHP) were the most prevalent among the seven studied phthalates, with the highest concentration reached by DEHP in a bottlenose dolphin (4697.34 ± 113.45 ng/g). Phthalates esters (PAEs) concentration were higher in bottlenose dolphins (Mean ∑ PAEs: 947.56 ± 1558.34 ng/g) compared to pilot whales (Mean ∑ PAEs: 229.98 ± 158.86 ng/g). In bottlenose dolphins, DEHP was the predominant phthalate, whereas in pilot whales, DEP and DBP were more prevalent. Health markers suggested pilot whales might suffer from poorer physiological conditions than bottlenose dolphins, although high metabolic differences were seen between the two species. Phthalate levels showed no differences by ecological or biological groups, seasons, or years. This study is the first to assess the extent of plastic additive contamination in free-ranging cetaceans from a remote oceanic island system, underscoring the intricate relationship between ecological niches and contaminant exposure. Monitoring these chemicals and their potential impacts is vital to assess wild population health, inform conservation strategies, and protect critical species and habitats.

Integrative taxonomy of an East Asian songbird indicates rapid dwarfism after island colonization

AbstractAnimals that colonize islands often undergo significant evolutionary changes in comparison with their continental counterparts as a response to specific island conditions. The pace of such changes can be relatively fast, which poses challenges in the evaluation of the taxonomic status of island taxa. The Japanese and Manchurian Bush Warbler species complex (Horornis diphone–canturians), which breeds in East Asia and the Japanese Archipelago, is such an avian example. This species complex exhibits significant morphological differentiation between different taxa, and the taxonomic status and phylogenetic relationships within the complex are debated. Here, we updated the taxonomy of this species complex and shed insight on its evolutionary history using multi‐locus phylogeographic and acoustic analyses. Our results support the conventional treatment of the two continental taxa borealis and canturians as subspecies of H. canturians, contrary to some recent proposals that they are affiliated to H. diphone. We also document a reduction in body size, that is dwarfism, and vocal divergence in the nominate subspecies H. d. diphone, which is endemic to the remote and isolated Ogasawara Islands. These changes may have happened following colonization of these islands, which was estimated to have taken place approximately 0.2 million years ago. Although H. d. diphone is clearly distinctive and deserves recognition as an evolutionarily significant unit, H. d. diphone and other H. diphone samples were not reciprocally monophyletic. Because of this lack of reciprocal monophyly and a relatively recent divergence time, we advocate maintaining its current subspecies status. We also detected reduced genetic diversity, measured as heterozygosity, in H. d. diphone. We suggest that conservation efforts in the Ogasawara Islands should prioritize the protection of this endemic subspecies. Collectively, our findings suggest that the separation between the populations on the East Asian continent and the Japanese Archipelago, followed by colonization of remote oceanic islands through long‐distance dispersal, underlie rapid phenotypic and genetic diversification of the Horornis diphone–canturians species complex.

Original plant diversity and ecosystems of a small, remote oceanic island (Corvo, Azores): Implications for biodiversity conservation

Remote islands harbour many endemic species and unique ecosystems. They are also some of the world's most human-impacted systems. It is essential to understand how island species and ecosystems behaved prior to major anthropogenic disruption as a basis for their conservation. This research aims to reconstruct the original, pre-colonial biodiversity of a remote oceanic island to understand the scale of past extinctions, vegetation changes and biodiversity knowledge gaps.We studied fossil remains from the North Atlantic island of Corvo (Azores), including pollen, charcoal, plant macrofossils, diatoms and geochemistry of wetland sediments from the central crater of the island, Caldeirão. A comprehensive list of current vascular plant species was compiled, along with a translation table comparing fossilized pollen to plant species and a framework for identifying extinctions and misclassifications.Pollen and macrofossils provide evidence for eight local extinctions from the island's flora and show that four species listed as ‘introduced’ are native. Up to 23 % of the pollen taxa represent extinct/misclassified species. Corvo's past environment was dynamic, shifting from glacial-era open vegetation to various Holocene forest communities, then almost completely deforested by fires, erosion and grazing following Portuguese colonisation. Historical human impacts explain high ecological turnover, several unrecorded extinctions and the present-day abundance of vegetation types like Sphagnum blanket mire.We use Corvo as a case study on how fossil inventories can address the Wallacean and Hookerian biodiversity knowledge gaps on remote islands. Accurate baselines allow stakeholders to make informed conservation decisions using limited financial and human resources, particularly on islands where profound anthropogenic disruption occurred before comprehensive ecological research.

Tropical seamounts as stepping-stones for coral reef fishes: range extensions and new regional distributions from mesophotic ecosystems in the Coral Sea, Australia

Seamounts and remote oceanic islands serve as valuable natural laboratories in which to study patterns and processes in marine biodiversity. A central hypothesis arising from studies of these systems is the ecological function of seamounts as stepping-stones for dispersal and population connectivity. Evidence of this mechanism exists for a range of taxa, including coral reef fishes, but is still lacking from many tropical seamounts in remote regions. In this study, we used remotely operated vehicles and baited remote underwater video systems to survey fish and benthic communities between 1 and 100 m on seamounts in the Coral Sea Marine Park (CSMP), Australia. We found evidence to support the stepping-stone model of ecological connectivity from new observations of 16 coral reef fishes which have previously not been recorded by quantitative surveys in the region. The widespread distribution of many of these species throughout the full latitudinal extent of the CSMP suggests that there is greater connectivity between mesophotic habitats in the Coral Sea and surrounding biogeographic regions than previously known. We also found a wide variety of mesophotic habitats and recorded significant depth range extensions for 78 fishes in these habitats. This further highlights the potential role of increased habitat area and heterogeneity in a stepping-stone effect throughout the region. Four of the fish occurrence records represent significant range extensions into the Coral Sea from adjacent biogeographic regions, and 13 fishes recorded by this study in the CSMP are not known from the neighbouring Great Barrier Reef, despite its close proximity. Although the Coral Sea remains relatively understudied, these findings suggest that larger-scale models of marine biogeography are relevant to communities in the region, particularly at mesophotic depths. Given the extent and the spatial arrangement of seamounts in the Coral Sea, our findings emphasise that the region is an important link between the centre of marine biodiversity in the Coral Triangle and the Southwest Pacific. Greater mesophotic sampling effort and genetic studies are necessary to understand the nature of connectivity and to establish the role of regional seamount chains, like the Coral Sea reefs, in broader marine biogeographic processes.

Frugivory and seed predation of fishtail palm (Caryota mitis Lour.) on the remote oceanic island of Narcondam, India

Abstract Oceanic islands, due to their evolutionary history and isolation, play a dual role of having high endemicity and being vulnerable to extinctions, with most known extinctions occurring on islands. Plant–animal interactions are particularly important on islands, as island systems generally have low redundancy and are more vulnerable to disruption either via extinction or by invasive species. Here, we examined the fruit removal and seed predation of a keystone palm, Caryota mitis, on Narcondam, a remote oceanic island. The island endemic Narcondam Hornbill (Rhyticeros narcondami) was the sole seed disperser of the palm (90 hours; N = 15 trees), with mean (± SE) visitation rate being 0.23 (± 0.06) individuals per hour and fruit removal rates of 3.5 (± 1.5; range: 0–16) fruits per visit, indicating a lack of redundancy in seed dispersal of the palm on this island. Whereas the invasive rodent, Rattus cf. tiomanicus, was the sole predator of palm seeds (N = 15 individual fruiting palms, 416 trap nights). Overall, 17.1% of the seeds placed (N = 375 seeds) were removed. Seeds placed under and away from the canopy, and at different densities (2 plots with 10 seeds each; 1 plot with 5 seeds, respectively), showed similar removal rates. This indicates density-independent seed predation and the lack of safe regeneration sites for Caryota mitis, with potential deleterious effects on subsequent stages of the ‘seed dispersal cycle’. Here, from a data-deficient site, we provide baseline information on the plant–frugivore interaction of a keystone palm and the potential impacts of an invasive rodent.

Microplastics in the insular marine environment of the Southwest Indian Ocean carry a microbiome including antimicrobial resistant (AMR) bacteria: A case study from Reunion Island

The increasing threats to ecosystems and humans from marine plastic pollution require a comprehensive assessment. We present a plastisphere case study from Reunion Island, a remote oceanic island located in the Southwest Indian Ocean, polluted by plastics. We characterized the plastic pollution on the island's coastal waters, described the associated microbiome, explored viable bacterial flora and the presence of antimicrobial resistant (AMR) bacteria. Reunion Island faces plastic pollution with up to 10,000 items/km2 in coastal water. These plastics host microbiomes dominated by Proteobacteria (80 %), including dominant genera such as Psychrobacter, Photobacterium, Pseudoalteromonas and Vibrio. Culturable microbiomes reach 107 CFU/g of microplastics, with dominance of Exiguobacterium and Pseudomonas. Plastics also carry AMR bacteria including β-lactam resistance. Thus, Southwest Indian Ocean islands are facing serious plastic pollution. This pollution requires vigilant monitoring as it harbors a plastisphere including AMR, that threatens pristine ecosystems and potentially human health through the marine food chain.

Population genetics of recent natural colonization by the bull-headed shrike (Lanius bucephalus; Aves) suggests the importance of recurrent immigration on remote islands

Abstract Founder effects and recurrent immigration are two major factors that might potentially contribute to genetic differentiation and population persistence in the early stage of remote island colonization. However, their relative importance remains controversial. By conducting population genetic analyses of four remote island populations of the bull-headed shrike (Lanius bucephalus) established naturally within several decades in Japan, we examined the contributions of founder effects and recurrent immigration to these island populations. Based on the standard genetic indices and population structure analyses using 15 microsatellite loci, we suggested island-specific scenarios of colonization. Notably, the founder effect strongly influenced genetic differentiation in the population on the most remote oceanic island, Chichi-jima Island, which, however, became extinct 20 years after colonization, possibly owing to a lack of recurrent immigration. In contrast, another oceanic island, Minami-Daito Island, was probably subjected to multiple recurrent immigration events from the mainland, which obscured any genetic differentiation previously established by the founder effect. Temporal samples collected over 8 years on this island confidently supported this scenario. Underlying the island-specific scenarios of colonization, we provide evidence that recurrent immigration strongly affected the population persistence, overwhelming the initial founder effects. We argue for the importance of recurrent immigration even in colonization of highly remote islands.

New terrestrial cyanobacteria from the Azores Islands: description of Venetifunis gen. nov. and new species of Albertania, Kovacikia and Pegethrix

ABSTRACT The taxonomy of cyanobacteria has advanced quickly with the use of molecular methods in combination with well-defined morphological and ecological characters. Using this approach, many taxonomical changes have occurred in the Synechococcales and Oscillatoriales, with the description of new families, genera and species. Here we present the study of four cyanobacterial strains from the Bank of Algae and Cyanobacteria of the Azores (BACA) culture collection, all isolated from the Azores Archipelago. The strains were genetically characterized through the amplification of the 16S rRNA gene and 16S-23S rRNA internal transcribed spacer (ITS) region, as well as morphologically by light and transmission electron microscopy. One of the strains presented a high genetic divergence from known genera of Synechococcales and was described as Venetifunis florensis gen. & sp. nov. (Trichocoleusaceae, Cyanobacteria). The remaining three strains were found to be new species of the genera Albertania, Kovacikia and Pegethrix. Venetifunis florensis was isolated from the shores of Lake Rasa in Flores Island, Kovacikia atmophytica sp. nov. is a new species mainly distinguished genetically from other Kovacikia species from Terceira Island. Albertania obscura sp. nov. was isolated from inside a volcanic cave in Terceira Island and is distinct both morphologically and genetically from the already described species. Pegethrix atlantica sp. nov. is a new morphologically and genetically different species isolated from São Miguel Island. The description of these new taxa increases the biogeographic knowledge of the four mentioned cyanobacterial genera to remote oceanic islands and new terrestrial habitats.

The relationship between naturalized alien and native plant species: insights from oceanic islands of the south-east Pacific over the last 200 years

Aim: The relationship between native and naturalized alien species has been widely studied, particularly across large geographic scales. However, our knowledge of the spatial and temporal variations of their relationships is still limited, particularly for remote oceanic islands such as those of the south-east Pacific and across islands and archipelagos. In this study, we aim to assess the relationships between native and naturalized alien species by analyzing their current patterns of species-area relationships at different spatial scales, in addition to temporal variations in species richness, over the last 200 years.Area: One island (Rapa Nui) and two archipelagos (Juan Fernandez and Desventuradas Islands) comprising a total of 11 oceanic islands of the south-east Pacific (OISEP).Methods: We assembled the most comprehensive dataset of the vascular flora of the OISEP from currently available island flora checklists and updated with recent publications. Each plant species was classified as being native or naturalized alien. We examined temporal changes by estimating species richness, naturalization rates and naturalized-to-native ratios over time based on the first collection year of each naturalized alien species. Then, we determined the best shape of naturalized alien species richness accumulation over time by contrasting the fit of lineal, exponential, sigmoidal and Weibull regressions. Finally, we analyzed the relationships between native and naturalized species firstly at the inter-archipelagic scale by fitting island species-area relationship models and secondly at the island scale by performing ranged major axis regression analysis on residual values.Results: The OISEP flora dataset contained 674 species of which 282 were native and 392 were naturalized alien. Native island species-area relationships were similar to those of the naturalized alien species. Naturalized alien species richness increased notably through time with two clear peaks in 1950 and 2000. A Weibull regression and an exponential shape over time were the most appropriate fits for naturalized alien species richness accumulations at the inter-archipelagic scale, which further emphasizes the notable increase in naturalized alien species richness experienced in the timeframe examined here.Main conclusions: The relationship between naturalized alien species richness and native species richness was found to be independent of the geographic scale. The number of naturalized alien species clearly exceeded the number of native species on most islands but also for the whole OISEP. The accumulation of newly detected naturalized alien species does not show any sign of saturation and it is likely that new species will arrive in the future. Increased efforts on monitoring, prevention and biosecurity are needed to halt biological invasions on these unique island ecosystems.

Human Settlement and Landscape Anthropization of Remote Oceanic Islands: A Comparison between Rapa Nui (Pacific Ocean) and the Azores (Atlantic Ocean).

The flora and vegetation of oceanic islands have been deeply affected by human settlement and further landscape modifications during prehistoric and historical times. The study of these transformations is of interest not only for understanding how current island biotas and ecological communities have been shaped but also for informing biodiversity and ecosystem conservation. This paper compares two oceanic insular entities of disparate geographical, environmental, biological, historical and cultural characteristics-Rapa Nui (Pacific Ocean) and the Azores Islands (Atlantic Ocean)-in terms of human settlement and further landscape anthropization. The similarities and differences between these islands/archipelagos are discussed considering their permanent colonization, the possibility of earlier settlements, the removal of the original forests and the further landscape transformations leading to either full floristic/vegetational degradation (Rapa Nui) or major replacement (Azores). This comparison uses evidence from varied disciplines, notably paleoecology, archaeology, anthropology and history, to obtain a holistic view of the development of the respective socioecological systems from a human ecodynamic perspective. The most relevant issues still to be resolved are identified and some prospects for future research are suggested. The cases of Rapa Nui and Azores Islands may help set a conceptual basis for ocean-wide global comparisons among oceanic islands/archipelagos.

A comparison of free-living and sponge-associated bacterial communities from a remote oceanic island with a focus on calcareous sponges.

Calcareous sponges are an often overlooked element of sponge communities. In contrast to most other sponges, calcareous sponges produce calcium carbonate spicules, as opposed to the siliceous spicules of most sponges. Here, we investigated the bacterial communities of 17 sponge species, including type and paratype specimens of recently described calcareous species, sampled off the remote island of Rodrigues, in the Indian Ocean. The main axis of variation in a PCO analysis of all samples separated noncalcareous sponge species, including Axinyssa aplysinoides, Cinachyrella aff. australiensis, Petrosia seychellensis, Ircinia aff. variabilis, Spongia ceylonensis, Plakinastrella aff. clipptertonensis, Agelas aff. ceylonica, Agelas aff. mauritiana, and Hyrtios erectus from calcareous sponges, the noncalcareous Biemna tubulata, sediment, and seawater. Overall, the bacterial communities of calcareous sponges revealed unique prokaryotic profiles with low abundances of several bacterial phyla, and relatively high abundances of other taxa, for example, the phyla Fibrobacterota, Proteobacteria, and the SAR324 clade, the class Alphaproteobacteria, and orders Cytophagales and Cyanobacteriales, although there was considerable variation among species. Calcareous sponges also had a high dominance of unknown bacterial operational taxonomic units (OTUs). Considering the unique nature of these communities, further studies are needed to better understand the environmental and ecological drivers of calcareous sponge-associated bacterial communities and their relevance as potential sources of novel microbes of biotechnological interest.

First report of marine debris in Car Nicobar, a remote oceanic Island in the Nicobar archipelago, Bay of Bengal

This study forms the first record to systematically quantify and classify the marine debris from Car Nicobar Island. Car Nicobar is a small remotely located Island in the Nicobar archipelago that is largely inhabited by Nicobarese indigenous people for ages. Considering their remote location and lack of baseline information on marine debris, we surveyed ten beaches in Car Nicobar to study the prevalence of marine debris. A total of 1438 debris items were recorded from the surveys of which plastic debris was found dominant (83.72%). Among the plastics, nets/ropes (38.87%) were found to be dominant followed by plastic bags, plastic bottles, polypropylene woven bags, plastic cans, floaters, and plastic cups. The number of debris was found to be highest in Malacca Jetty (7.2 nos/m2) and least in Mus Jetty (1.28 nos/m2). Land-based debris items from recreational and shoreline activities constituted majorly (54.52%) followed by sea-based sources such as shipping, fishing, and dumping activities (45.48%). Hierarchical Cluster Analysis (HCA) revealed that Malacca Jetty exhibited a distinct pattern of debris accumulation. Kriging interpolation was applied to understand the possible prevalence of marine debris around the coast of Car Nicobar Island. Plastic debris belonging to nearby countries such as Indonesia, Thailand, Malaysia, Myanmar, etc. was also recorded in our surveys. Shipping-based debris could be a probable source of foreign debris due to the proximity of the Nicobar archipelago to the Strait of Malacca, being one of the busiest shipping routes in the world. The baseline information generated from this study could assist the decision-makers to initiate proactive measures toward effective management of marine debris on Car Nicobar Island.

First metal and metalloid study assessment for the Black Triggerfish Melichthys niger (Bloch, 1786): Baseline data from a pristine South Atlantic oceanic island

Metal and metalloid concentrations in Black Triggerfish, Melichthys niger (Tetraodontiformes, Balistidae), and sediments from Trindade Island, an isolated, pristine, and understudied environment in the Southwestern Atlantic Ocean were determined. Several elements were detected in sediment, including Rare Earth Elements (REE). Hg and the REE Nd were, however, not detected. Elements determined in triggerfish are indicative of systemic circulation and the presence of toxic elements indicates an exposure source. No significant associations were detected between elements in fish organs and total length, suggesting no bioaccumulation with age, nor between organs and sediment, indicating probable dietary origin. Biliary excretion indicated a local chronic source of As and Cd and non-quantifiable REE elimination. Hg concentrations were over thresholds that affect fish biochemistry processes. These baseline data are valuable concerning elemental contamination in remote oceanic islands, with the potential to be applied to future biomonitoring efforts and conservation measures for reef ecosystems worldwide.

Success factors of great oceanic dispersers: Case of Squamata in the Pacific Ocean

AbstractThe Pacific Ocean is the largest in the world, and it contains many remote archipelagos, some of which are distant more than 4000 km from continents. Despite their isolation, these archipelagos harbour diverse assemblages of squamate reptiles (lizards and snakes), and these species differ greatly in their dispersal ranges. This study tested the hypothesis that there is a spatial effect on the variation among species in dispersal ability and that it is also associated with the evolutionary relationships among species and their life‐history strategies (body size and reproductive mode). The results indicated greater spatial than phylogenetic effects on the variables describing interspecific dispersal. The unisexual reproduction mode in squamates is not associated with a greater ability to colonize than sexual species that rely on similar mechanisms of dispersal. The higher reproductive rate of unisexual taxa might be initially advantageous for establishment on remote oceanic islands because of the unlikely arrival of sexual congenerics, which are frequently superior competitors in island ecosystems. Body size tends to exert a negative effect on the dispersal capacity of island squamates, but this relationship is positive in a subgroup of recently introduced commensal species.

Assessing microplastic exposure of the Critically Endangered Mediterranean monk seal (Monachus monachus) on a remote oceanic island

Microplastics (<5 mm) are a ubiquitous marine pollutant which are highly bioavailable to marine organisms across all trophic levels. Marine predators are especially vulnerable to microplastic pollution through direct and indirect ingestion (e.g., trophic transfer) due to their high trophic position. In particular, oceanic islands are more susceptible to plastic accumulation, increasing the relative number of microplastics in the environment that are available for consumption. The dynamics of microplastic accumulation in marine predators inhabiting remote islands, however, is sparsely documented. Here we describe microplastic exposure in the Critically Endangered Mediterranean monk seal (Monachus monachus) from the Madeira archipelago (Northeast Atlantic) using scat-based analysis. Microplastics were recovered from 18 scat samples collected between 2014−2021 and were characterized to the polymer level using Fourier-Transform Infrared (u-FTIR) spectroscopy. A total of 390 microplastic particles were recovered, ranging between 0.2−8.6 particles g−1 dry weight (mean 1.84 ± 2.14 particles g−1) consisting mainly of fragments (69 %) of various sizes and polymer composition (e.g., PE, PET, PS). Microplastic prevalence (100 % of samples analysed) was higher than what has been previously recorded using scat-based analysis in other pinniped species. Our results suggest that the levels of microplastic pollution in the coastal food-web in the Madeira archipelago are relatively high, placing higher-trophic level organisms at increased risk of microplastic consumption, including humans. This study provides the first insights into microplastic exposure to Madeira's monk seals that may contribute to future management decisions for the species and their long-term survival.

Climatic niche pre-adaptation facilitated island colonization followed by budding speciation in the Madeiran ivy (Hedera maderensis, Araliaceae).

The path followed by species in the colonization of remote oceanic islands ultimately depends on their phylogenetic constraints and ecological responses. In this study, we aim to evaluate the relative role of geographical and ecological forces in the origin and evolution of the Madeiran ivy (Hedera maderensis), a single-species endemic belonging to the western polyploid clade of Hedera. To determine the phylogenetic placement of H. maderensis within the western polyploid clade, we analyzed 40 populations (92 individuals) using genotyping-by-sequencing and including Hedera helix as outgroup. Climatic niche differences among the study species were evaluated using a database with 867 records representing the entire species ranges. To test species responses to climate, 13 vegetative and reproductive functional traits were examined for 70 populations (335 individuals). Phylogenomic results revealed a nested pattern with H. maderensis embedded within the south-western Iberian H. iberica. Gradual niche differentiation from the coldest and most continental populations of H. iberica to the warm and stable coastal population sister to H. maderensis parallels the geographical pattern observed in the phylogeny. Similarity in functional traits is observed for H. maderensis and H. iberica. The two species show leaves with higher specific leaf area (SLA), lower leaf dry matter content (LDMC) and thickness and fruits with lower pulp fraction than the other western polyploid species H. hibernica. Acquisition of a Macaronesian climatic niche and the associated functional syndrome in mainland European ivies (leaves with high SLA, and low LDMC and thickness, and fruits with less pulp content) was a key step in the colonization of Madeira by the H. iberica/H. maderensis lineage, which points to climatic pre-adaptation as key in the success of island colonization (dispersal and establishment). Once in Madeira, budding speciation was driven by geographical isolation, while ecological processes are regarded as secondary forces with a putative impact in the lack of further in situ diversification.

Molecular phylogenetics reveals the evolutionary history of marine fishes (Actinopterygii) endemic to the subtropical islands of the Southwest Pacific

Remote oceanic islands of the Pacific host elevated levels of actinopterygian (ray-finned fishes) endemism. Characterizing the evolutionary histories of these endemics has provided insight into the generation and maintenance of marine biodiversity in many regions. The subtropical islands of Lord Howe, Norfolk, and Rangitāhua (Kermadec) in the Southwest Pacific are yet to be comprehensively studied. Here, we characterize the spatio-temporal diversification of marine fishes endemic to these Southwest Pacific islands by combining molecular phylogenies and the geographic distribution of species. We built Bayesian ultrametric trees based on open-access and newly generated sequences for five mitochondrial and ten nuclear loci, and using fossil data for time calibration. We present the most comprehensive phylogenies to date for marine ray-finned fish genera, comprising 34 species endemic to the islands, including the first phylogenetic placements for 11 endemics. Overall, our topologies confirm the species status of all endemics, including three undescribed taxa. Our phylogenies highlight the predominant affinity of these endemics with the Australian fish fauna (53%), followed by the East Pacific (15%), and individual cases where the closest sister taxon of our endemic is found in the Northwest Pacific and wider Indo-Pacific. Nonetheless, for a quarter of our focal endemics, their geographic affinity remains unresolved due to sampling gaps within their genera. Our divergence time estimates reveal that the majority of endemic lineages (67.6%) diverged after the emergence of Lord Howe (6.92 Ma), the oldest subtropical island in the Southwest Pacific, suggesting that these islands have promoted diversification. However, divergence ages of some endemics pre-date the emergence of the islands, suggesting they may have originated outside of these islands, or, in some cases, ages may be overestimated due to unsampled taxa. To fully understand the role of the Southwest Pacific subtropical islands as a ‘cradle’ for diversification, our study advocates for further regional surveys focused on tissue collection for DNA analysis.

A global molecular phylogeny yields insights into the dispersal and invasion history of Junonia, a butterfly genus with remarkable dispersal abilities.

The nymphalid butterfly genus Junonia has remarkable dispersal abilities. Occurring on every continent except Europe and Antarctica, Junonia are often among the only butterflies on remote oceanic islands. The biogeography of Junonia has been controversial, plagued by taxonomic disputes, small phylogenetic datasets, incomplete taxon sampling, and shared interspecific mitochondrial haplotypes. Junonia originated in Africa but its route into the New World remains unknown. Presented here is, to our knowledge, the most comprehensive Junonia phylogeny to date, using full mitogenomes and nuclear ribosomal RNA repeats from 40 of 47 described species. Junonia is monophyletic and the genus Salamis is its probable sister clade. Genetic exchange between Indo-Pacific Junonia villida and New World Junonia vestina is evident, suggesting a trans-Pacific route into the New World. However, in both phylogenies, the sister clades to most New World Junonia contain both African and Asian species. Multiple trans-Atlantic or trans-Pacificinvasions could have contributed to New World diversification. Hybridization and lateral transfer of mitogenomes, already well-documented in New World Junonia, also occurs in at least two Old World lineages (Junonia orithya/Junonia hierta and Junonia iphita/Junonia hedonia). Variation associated with reticulate evolution creates challenges for phylogenetic reconstruction, but also may have contributed to patterns of speciation and diversification in this genus.