Search Results (72)

The fossil record of marine molluscs has been used as evidence to test marine island biogeography theories and to complement the evolutionary patterns of biodiversity and endemicity found in oceanic islands and archipelagos. Although long-distance dispersal patterns have been the subject of several studies, important questions may still be posed. For instance, are these processes random, or do they show distinct patterns? And are they restricted to “windows of opportunities”, or do they occur continuously? In the NE Atlantic, the dispersal of tropical species towards higher latitudes associated with the last interglacial period is a well-known phenomenon. However, the most probable dispersal route remains a matter of debate. To test these ideas, we used the Atlantic and Mediterranean last interglacial fossil records, and compared the present geographic distribution of shallow-water marine molluscs with that registered during the last interglacial episode, aiming to detect changes. Our results show that 27 species became extinct during the course of the last glacial episode, and that 55 marine mollusc species (43 gastropods and 12 bivalves) are ecostratigraphic indicators for the MIS 5e fossiliferous deposits in the Macaronesian archipelagos, the Atlantic coasts of Morocco, and the Mediterranean. Finally, we provide arguments for the timing of dispersal, which occurred during a restricted “window of opportunity” associated with the inception of the last interglacial, and for the most probable route of dispersal of the tropical species, most of them denoting a Cabo Verdean origin. Full article

Geographic isolation can shape genetic variation and structure, leading to divergence between island and mainland populations. The Oriental Garden lizard (Calotes versicolor Daudin, 1802) is a widespread agamid reptile in Asia, occurring across diverse habitats from continental Southeast Asia to offshore islands. We examined mitochondrial cytochrome c oxidase subunit I (CO1) sequence variation in 143 individuals from 23 localities across the Andaman Sea and Gulf of Thailand to assess genetic diversity and structure between insular and mainland populations. Forty-six haplotypes (Cve1–Cve46) were identified, with haplotype diversity (Hd) ranging from 0.500 to 1.000 and nucleotide diversity (π) from 0.0057 to 0.0265. AMOVA revealed low to moderate differentiation between island and mainland groups in the Andaman Sea (F_CT = 0.075, p > 0.05) and negligible differentiation in the Gulf of Thailand (F_CT = 0.009, p > 0.05). Haplotype networks and PCoA showed clustering of most island and mainland populations within regions, with some localized divergence. Divergence-time analysis indicated that lineages split within the last 0.5 million years ago (Ma), coinciding with late Pleistocene climatic oscillations and sea-level changes. Species delimitation analyses supported three major lineages, including a geographically restricted clade confined to Trat Province and Phuket Island. These results suggest that C. versicolor populations are structured more by regional geography than strict island–mainland separation, reflecting historical connectivity and contemporary gene flow. The findings contribute to understanding reptile biogeography in Southeast Asia and highlight populations of conservation value. Full article

The Philippines and the Papuan archipelagos harbor a vast diversity of pygmy grasshoppers, including the pygmy devils of the genera Xistra and Tegotettix, as well as visually similar taxa reviewed in this study. A new tribe, two new genera, a new subgenus, three new species, and 24 new or resurrected taxonomic combinations are proposed in this study. A new colorful wingless genus and species, Almacris alleochroa gen. et sp. nov., is described from Mindanao. Taxonomic reshuffling of the genus Xistra is performed—a new subgenus is described, Tegoxistra subgen. nov., to include X. derijei, X. corniculata, and X. cristifera, while the nominotypical subgenus becomes restricted to X. gogorzae and X. sagittaria. All other species previously assigned to Xistra are herewith moved to Xistrella, resulting in 20 new combinations. The genus Ginixistra gen. nov. (Exanimini)—whose members show remarkable similarity to Fiji-endemic Fijixistra—is described for G. novaeguineae, G. davorkae sp. nov., and G. novaebritanniae sp. nov. from New Guinea and New Britain. The new tribe Xistrellini trib. nov. is established to accommodate Afrosystolederus, Bannatettix, Kanakacris, Phaesticus, Pseudoparatettix, Pseudosystolederus, Pseudoxistrella, Synalibas, Systolederus, Teredorus, and Xistrella. Previous molecular phylogenetic studies have confirmed Xistrellini monophyly and suggested that the ancestor of this tribe may have originated during the Cretaceous period, approximately 127–100 million years ago (mya). Full article

During the last two decades, the Macaronesian archipelagos have been the focus of multiple studies targeting the abundant and diversified fossil record from late Neogene and Quaternary deposits. This record of past biota, ecosystems and climates is crucial for understanding the impact of glacial–interglacial cycles on Atlantic littoral marine organisms. Coupled with ongoing studies on the factors responsible for global climate change and associated sea-level variations, they contributed decisively towards the development of the modern marine island biogeography theory. Our current knowledge of the evolutionary and biogeographic history of the past and extant, shallow-water marine organisms from the Macaronesian geographic region relies on detailed analysis of many individual fossiliferous outcrops by means of quantitative and qualitative methodologies. Here, we focus on the fossil record of a newly studied MIS 5e outcrop at Pedra-que-pica (PQP), on Santa Maria Island (Azores Archipelago, Portugal). This multidisciplinary work integrates geology, paleontology and biology, providing the first detailed description of the sedimentary facies and stratigraphic framework of the PQP MIS 5e sequence that, coupled with the documentation of the biodiversity and ecological composition of PQP molluscan assemblages, allows us to produce a paleoecological reconstruction and to compare PQP with other last interglacial outcrops from Santa Maria Island. Our results increase the number of the Azorean MIS 5e marine molluscs to 140 taxa (116 Gastropoda and 24 Bivalvia). Ervilia castanea (Montagu, 1803) is the most abundant bivalve, while Bittium nanum (Mayer, 1864) and Melarhaphe neritoides (Linnaeus, 1758) are the most abundant gastropod species. In addition, this work emphasizes the crucial importance of complementing quantitative collecting with qualitative surveys of the fossiliferous outcrops, because nearly 42% of the bivalve species and 28% of the gastropod taxa would be missed if only quantitative samples were used. Derivation of Hill numbers and rarefaction curves both indicate that the sampling effort should be increased at PQP. Thus, although Santa Maria Island is recognized by the scientific community as one of the best-studied islands regarding the last interglacial fossil record, this study emphasizes the need to continue with similar efforts in less known outcrops on the island. Full article

Many studies have examined how species are shifting their ranges poleward in response to climate change, using statistical approaches such as graphical analyses, t-tests, correlation analyses, and circular data methods. However, these methods are often constrained by assumptions of linearity or reliance on a single explanatory variable, which limits their ecological applicability. This study introduces a new statistical methodology to evaluate the significance of poleward range expansion, aiming to overcome these limitations and improve the robustness of ecological inference. We developed four parameterized nonlinear models—simple, multivariable, fixed, and transformed—to characterize the relationship between latitude and species richness across 1253 islands. Model parameters were estimated using the Gauss–Newton algorithm, and residuals were calculated as the difference between observed and predicted values. To test for distributional shifts, likelihood ratio tests were applied to the residuals, with statistical significance assessed using chi-square statistics and p-values derived from the −2 log-likelihood ratio. Finally, an intuitive indicator based on the fitted models was introduced to evaluate the direction of range shifts, thereby providing a direct means of identifying northward expansion trends under climate change. Applying this framework revealed significant poleward shifts of warm temperate and subtropical species (χ² = 52.4–61.3; p < 0.001). Among the four models, the multivariable model incorporating island area provided the best fit (AIC, BIC), reflecting its ability to account for collinearity. Taken together, these results underscore the robustness and ecological relevance of the methodology, demonstrating its utility for detecting species-specific range shifts and comparing alternative models under climate change. Full article

Investigating altitudinal distribution patterns of species richness represents a fundamental research objective in biogeography and community ecology. Hainan Island has tropical rainforests ranging from sea level to >1800 m a.s.l., with various animal species, including reptiles such as geckos. Information on the altitudinal distribution patterns of animal diversity on Hainan Island is limited. Thus, from October 2020 to June 2023, we surveyed Gekkonidae species on Diaoluo Mountain and Jianfeng Ridge in the Hainan Tropical Rainforest National Park using a line transect method. The two study sites were divided into seven altitudinal zones at intervals of 150 m from 31 to 1080 m a.s.l. We tested correlations between abundance and species diversity indices and altitude. Five gecko species were identified. The endemic Gekko similignum mainly occurred at high-altitude areas on both mountains, whereas Hemidactylus frenatus occupied low-altitude areas. Gehyra mutilata had the lowest abundance among all species at all altitudes. Diaoluo Mountain exhibited a higher species diversity and abundance than Jianfeng Ridge. Geckos on Diaoluo Mountain were mainly distributed between 31 and 920 m a.s.l., presenting a bimodal distribution, with peaks appearing in altitudinal zones II (181–330 m a.s.l.) and VI (781–930 m a.s.l.). The gecko distribution on Jianfeng Ridge ranged from 31 to 948 m a.s.l., presenting a unimodal distribution, with a peak in altitudinal zone V (631–780 m a.s.l.). Full article

Botiidae is a small family of freshwater fishes distributed across Southeast Asia, South Asia, and East Asia. It comprises two subfamilies: the diploid Leptobotiinae and the tetraploid Botiinae. Whether species in the Botiinae are autotetraploids or allotetraploids and how many polyploidization events occurred during the evolution of this subfamily remain open questions. The phylogenetic relationships and biogeography of the Botiidae also require further investigation. In the current study, we compared phylogenetic trees constructed using DNA sequences from the mitochondrial genome and five phased nuclear genes. We also performed whole genome sequencing for two tetraploid species: Chromobotia macracanthus and Yasuhikotakia modesta. Genome profiling of five botiine species suggests that they are likely of allotetraploid origin. Nuclear gene tree topologies indicate that the tetraploidization of the Botiinae occurred only once in the common ancestor of this subfamily. Although the possible maternal progenitor and paternal progenitor of the Botiinae cannot be determined, the subfamily Leptobotiinae can be excluded as a progenitor. The gene trees built in this study generally agree on the following sister group relationships: Leptobotiinae/Botiinae, Leptobotia/Parabotia, Chromobotia/Botia, Yasuhikotakia/Syncrossus, and Sinibotia/Ambastaia. Clades formed by the last two generic pairs are also sisters to each other. Timetree analyses and ancestral range reconstruction suggest that the family Botiidae might have originated in East Asia and Mainland Southeast Asia approximately 51 million years ago and later dispersed to South Asia and the islands of Southeast Asia. Full article

The taxonomic complexity of Phoenix palms in the Canary Islands, where multiple morphotypes representing at least four taxa currently exist, presents significant challenges for archaeobotanical identification. We developed a Bayesian probabilistic framework to identify archaeological Phoenix seeds within the context of genus-wide morphological diversity. Our analysis incorporated thousands of specimens including modern reference collections, archaeological materials from pre-Hispanic sites in Gran Canaria and La Gomera (3–16th centuries CE), and fossil remains. We recorded quantitative measurements and qualitative characteristics for each specimen. To understand taphonomic effects, we conducted experimental carbonization of modern P. canariensis seeds and documented the resulting morphological alterations. We performed a hierarchical cluster analysis using Ward’s minimum variance method and calculated taxonomic assignment probabilities for archaeological specimens using Bayesian inference, where likelihood was derived from taxon proportions within assigned clusters. The results indicated a high probability (0.69–1.00) that the archaeological specimens belong to P. canariensis var. canariensis, with no evidence for P. dactylifera presence. These findings provide critical insights into pre-Hispanic exploitation of Phoenix palms, particularly the endemic P. canariensis, which served as a vital resource, providing food, fiber, and construction materials. Our methodological approach offers a robust framework for addressing taxonomic uncertainty in archaeobotanical research while enhancing understanding of historical palm biogeography and resource use patterns in the Canary Islands. Full article

Urban gardens can be crucial for preserving the biodiversity in cities, but their construction often leads to shifts in local ant communities due to drastic habitat changes. Over time, ant communities can recover as species arrive from surrounding habitats. In this study, we explored ant community dynamics over ten years in four gardens of varying maturity on a university campus in South Spain. We examined: (1) ant community composition in the gardens and surrounding natural/seminatural areas; (2) changes in biodiversity over time; (3) indicator values of species in the campus; and (4) population dynamics of the most representative species. We found distinct ant community compositions in gardens and natural/seminatural habitats. The ant community in older gardens showed greater similarity to surrounding natural areas than in young gardens. In the youngest garden, biodiversity initially declined post-construction but later increased to levels comparable to older gardens. Exotic species were more abundant in the young garden, and the population of native species like the garden ant Lasius niger increased over the years. We found that disturbances promote the establishment of exotic species, regardless of habitat maturity. We emphasize the importance of a context-dependent interpretation of species bioindicator information to assess habitat ecological status accurately. Full article

Understanding the distribution patterns and driving mechanisms of bamboo species diversity on islands is essential for advancing knowledge of island ecosystem processes and informing strategies for bamboo resource conservation and management. This study utilized standardized major axis regression (SMA) to assess the effects of island area and isolation on bamboo species across 30 islands in Fujian, China. Furthermore, a partial least squares structural equation model (PLS-SEM) was constructed to explore the driving mechanisms underlying bamboo species richness. This analysis incorporated six key environmental factors—island size, isolation, shape, climate, development intensity, and habitat heterogeneity—spanning a total of 12 variables. The primary findings were as follows: (1) Eight genera and twenty-nine bamboo species were identified on Fujian islands. Species richness increased significantly with island area, consistent with the theory of area effects, while isolation had no significant impact on richness. (2) Different reproductive types exhibited distinct responses to environmental conditions. This was evident in the species–area relationship slopes (z-values): SR = 2.07; monopodial = 0.94; sympodial = 0.82; and polycyclic = 0.44. These variations highlight the ecological adaptability and functional traits of different reproductive strategies within island ecosystems. (3) Among the six environmental factors, island area exerted the greatest influence on species richness, underscoring its role as the primary driver of bamboo diversity and reproductive strategies. (4) Island area and isolation also impacted species richness indirectly through their effects on development intensity. In conclusion, the bamboo species richness and reproductive types on Fujian islands are primarily shaped by island area, followed by development intensity and habitat heterogeneity. In contrast, climate, island shape, and isolation play relatively minor roles. This study provides critical insights into the interplay of island area, isolation, shape, climate, development intensity, and habitat heterogeneity in shaping bamboo diversity. The findings offer a valuable foundation for bamboo resource conservation, island ecosystem management, and sustainable development. Full article

The Neotropics are the most species-rich region on Earth, and spectacular diversification rates in plants are reported in plants, mostly occurring in oceanic archipelagos, making Neotropical and island plant lineages a model for macro-evolutionary studies. The genus Lycium in the Solanaceae family, originating from the Neotropics and exhibiting a unique disjunct geography across several islands, is therefore expected to experience exceptional diversification events. In this study, we aimed to quantify the diversification trajectories of the genus Lycium to elucidate the diversification events within the genus. We compiled a DNA matrix of six markers on 75% of all the species in the genus to reconstruct a dated phylogeny. Based on this phylogeny, we first revisited the historical biogeography of the genus. Then, we fitted a Compound Poisson Process on Mass Extinction Time model to investigate the following key evolutionary events: speciation rate, extinction rate, as well as mass extinction events. Our analysis confirmed that South America is the origin of the genus, which may have undergone a suite of successive long-distance dispersals. Also, we found that most species arose as recently as 5 million years ago, and that the diversification rate found is among the slowest rates in the plant kingdom. This is likely shaped by the multiple speciation and extinction rate shifts that we also detected throughout the evolutionary history of the genus, including one mass extinction at the early stage of its evolutionary history. However, both speciation and extinction rates remain roughly constant over time, leading to a gradual species accumulation over time. Full article

Invasive alien plants (IAPs) pose a significant threat to island biodiversity and severely impact ecosystems. Understanding the species–area relationship and environmental determinants of growth forms for IAP species on subtropical islands is crucial for establishing an IAP’s early warning mechanism, enhancing island ecological management, and protecting the ecosystems of Fujian and other subtropical islands. The study identified significant species–area relationships for IAPs and different life-form plants (trees, shrubs, and herbs), with slopes of 0.27, 0.16, 0.15, and 0.24, respectively. The small island effect does not apply to all species. Isolation has little effect on species richness, and the IAPs on Fujian islands do not conform to the isolation effect in island biogeography. Landscape factors are the main determinants of IAPs and different life-form species richness, with area, shape index, and perimeter–area ratio being the three primary landscape factors. These environmental factors are closely related to habitat heterogeneity. Besides landscape factors, different life forms respond differently to environmental factors. Climate drives the species richness distribution of shrubs and herbs, while trees are mainly influenced by human activities. Overall, landscape, human disturbance, and climate jointly drive the distribution of IAPs, with landscape factors being the most significant. Full article

This paper provides new data on the ladybird beetles (Coccinellidae) from two islands in the Canary archipelago: Tenerife, the largest island, and La Gomera, the second smallest. As they clearly differ in size but are similar in location and geological age, they are a suitable model for testing the species–area relationship. Our study shows that, in line with this main assumption of the theory of island biogeography, clearly more species occur on a large island (Tenerife) than on a small one (La Gomera). The field surveys documented the occurrence of 35 ladybird species on Tenerife (including 5 not previously reported from this island) and of 20 species on La Gomera (2 species new to the island). Coelopterus sp. collected on Tenerife (a single female that could not be identified to species) is the first record of this genus for the whole Canary Islands. Taking our data and previously published records into account, 47 species of Coccinellidae are known to occur on Tenerife and 26 species on La Gomera. Tenerife has by far the richest ladybird fauna of all the Canary Islands (the next in line, Gran Canaria, has 41 recorded species), but it also has the highest number of non-native ladybird species. All of the ten non-native species recorded in the Canary Islands are found on Tenerife, and for most of them, Tenerife was the island of their first appearance in the archipelago. This island, much more distant from the mainland than the other relatively large islands (Fuerteventura, Lanzarote), appears to be the main recipient of ladybirds immigrating to the Canary Islands. Tenerife can play this role probably because of its great habitat diversity and altitude variation, as well as intensive tourism and trade-related transport. Full article

Studies performed in North America, Africa, and South America have led to the isolation of four new species of Kastovskya, a filamentous cyanobacterial genus that before this manuscript had only one species, Kastovskya adunca from Chile. Kastovskya nitens and K. viridissima were isolated from soils on San Nicolas Island, K. sahariensis was isolated from hypolithic habitats from the Sahara Desert in Algeria, and K. circularithylacoides was isolated from hypolithic habitats in Chile. The molecular analyses are corroborated by morphological data, morphometric analysis, and ecological and biogeographical considerations for robust polyphasic descriptions of all taxa. The peculiar transatlantic distribution of this genus bears similarity to other taxa in recently published studies and is in agreement with a hypothesis suggesting that cyanobacteria in Africa may disperse to the Americas on dust particles during windstorms. This work is unusual in that species in a single rare cyanobacterial genus with a disjunct distribution are described simultaneously from three continents. The 16S rRNA gene analyses performed for this study also revealed that another recent genus, Arizonema, is clearly a later synonym of Symplocastrum. This issue is resolved here with the collapsing of the type species Arizonema commune into Symplocastrum flechtnerae. Full article

Plant invasions threaten the biodiversity of islands, causing serious impacts on their ecosystems. To investigate the distribution patterns of invasive alien plants on subtropical islands, the environmental determinants of species richness, and the growth forms of invasive alien plants, this study analyzed the composition and origin of invasive alien plants on 77 islands in Fujian. The similarity in the distribution of invasive alien plants between islands was assessed using the UPGMA. Moreover, feature selection, best-subset regression, and variance decomposition were performed using 19 environmental variables characterizing climate, anthropogenic disturbance, and landscape/geography, as well as the species richness and growth forms of invasive alien plants. Through the analysis, the main environmental factors affecting the species richness and growth forms of invasive alien plants on the Fujian islands were identified. The results showed 142 species of invasive alien plants in 38 families and 102 genera on 77 islands in Fujian. Annual herbs constituted the most representative growth form of invasive alien plants and tropical America was the main origin of invasive alien plants. The distribution of invasive alien plants across the 77 islands in Fujian showed a high degree of similarity, suggesting a nested pattern in their distribution. The proportions of building and farmland area (BFA), island area (A), and maximum elevation (ME) were the main driving factors of species richness and growth forms for invasive alien plants. In particular, BFA played a key role in driving plant invasion. The results of this study can help establish an early warning mechanism for invasive alien plants and better implement island ecological management, which are important for the protection of subtropical island ecosystems. Full article