Island biogeography

Roadkill in a Mediterranean island: Evaluating ten-years of official records

Roadkill is a global issue contributing to biodiversity decline which is increasingly recognized by scientists and decision-makers. In Cyprus, a biodiversity hotspot with one of the highest road densities in Europe, the impact of roads on wildlife has been largely overlooked due to the absence of life-threatening collisions. We analysed data from a 10-year roadkill dataset (2013-2022) collected systematically by the Department of Public Works across 27 main roads, primarily aimed at driver safety. Due to the absence of spatial attributes for roadkill locations, the dataset was analysed to identify taxonomic, seasonal, and temporal roadkill trends in Cyprus for the first time. A total of 1,985 roadkill incidents were recorded, involving seven wildlife taxa: foxes (44%), birds (26%), hedgehogs (11.5%), snakes (7%), hares, rats, and lizards. Most roadkill occurred in the Nicosia district (65%). Statistical analyses using chi-square tests with post-hoc Bonferroni corrections revealed strong associations between road types and taxa. Fox and bird roadkill incidents were most common on highways, while hedgehogs and snakes were frequent on secondary interurban or rural roads. Roads near protected areas exhibited higher roadkill frequencies than highways. A positive relationship between traffic volume and roadkill risk was evident, with higher traffic roads posing greater risks. Seasonal patterns showed increased roadkill during spring and summer, peaking in June. This synthesis provides crucial insights into roadkill patterns, offering guidance for conservation and mitigation actions. However, the current monitoring system, focused on driver safety, is inadequate for comprehensive roadkill reporting. Key limitations, such as the absence of spatial data and weaknesses in the protocol, have been identified, with recommendations for improvement proposed to enhance future monitoring efforts.

Biome conservatism prevailed in repeated long-distance colonization of Madagascar's mountains by Helichrysum (Compositae, Gnaphalieae)

Colonization and diversification processes are responsible for the distinctiveness of island biotas, with Madagascar standing out as abiodiversity hotspot exceptionally rich in species and endemism. Regardless of its significance, the evolutionary history and diversification drivers of Madagascar's flora remain understudied. Here we focus on Helichrysum (Compositae, Gnaphalieae) to investigate the evolutionary and biogeographic origins of the Malagasy flora. We inferred a highly resolved phylogeny based on target-enrichment data from 327 species (including 51 % of Malagasy endemics) and conducted ancestral range estimation analyses. Our results revealed at least six trans-oceanic dispersal events from different African regions to Madagascar during the Pliocene. In this process, biome conservatism prevailed, as evidenced by similarities between Malagasy lineages and their African relatives. The southern African grasslands, known to be the center of diversification and the main source of African Helichrysum lineages, played a key role in the colonization of Madagascar as the ancestral source area of at least three clades. The Tropical Afromontane region was revealed as the source of at least two montane Malagasy lineages that substantially radiated in-situ. Finally, a dispersal event from southwestern Africa led to a lineage represented by a single species adapted to the island's southwestern arid conditions. The main radiations of Helichrysum in Madagascar's mountains occurred within the last 2 My, coinciding with a transition towards cooler and drier conditions and the expansion of open habitats, likely driven by a combination of geographic and ecological speciation. Overall, our findings highlight the affinities between the montane floras of continental Africa and Madagascar.

Spatial Distribution Patterns, Environmental Drivers, and Hotspot Dynamics of the European Rabbit on a Mediterranean Island: Implications for Conservation and Management

The European rabbit (Oryctolagus cuniculus) presents a significant conservation and management challenge in Greece. While it has been listed in national biodiversity assessments, its population dynamics on the island of Lemnos demonstrate the characteristics of a highly adaptable and rapidly expanding species, exerting substantial ecological and economic impacts. Addressing this issue requires a spatially explicit understanding of its distribution patterns and habitat preferences, particularly given its extensive population growth over the past three decades. To this end, we conducted 40 field surveys across the island, documenting 1534 presence records of the species. We applied Kernel Density Estimation, Getis-Ord Gi *, and Anselin Local Moran's I to identify the spatial distribution patterns and significant hotspots. A spatial lag model was used to quantify hotspot intensity and clustering dynamics, while abiotic, biotic, and anthropogenic factors were analyzed to assess habitat associations. Our results revealed that rabbit hotspots are predominantly concentrated in fertile lowland agroecosystems, with nearly 60% of high-density areas overlapping conservation zones. Soil and field conditions, grazing-supporting landscapes, and arable and subsidized agricultural areas emerged as significant predictors of O. cuniculus presence. The observed spatial dependencies indicated that while hotspot intensities and clustering dynamics are influenced by the conditions in neighboring areas, habitat characteristics remain fundamental in shaping their distribution, highlighting the broader landscape-scale spatial patterns affecting rabbit populations. These findings underscore the necessity of adopting spatially informed management strategies that mitigate agricultural impacts while accounting for interconnected spatial dynamics, providing a foundation for informed decision-making to manage rabbit populations while balancing conservation and agricultural priorities.

Comparative Patterns of Sex Expression and Sex Ratios in Island and Continental Bryophyte Populations

Reproductive biology patterns are crucial for understanding the dynamics and evolution of plants. This is particularly relevant in bryophytes, where sex expression and reproductive success can vary significantly with environmental conditions. Islands, with their isolated and diverse environments, provide natural laboratories to explore these dynamics. In this study, we investigate sex expression, the phenotypic sex ratio, and sporophyte production in one moss (Exsertotheca intermedia) and three liverwort species (Frullania polysticta, Frullania teneriffae, Porella canariensis) across their entire distribution range. Depending on the species, the geographic range includes the Canary Islands, Madeira, the Azores, the Iberian Peninsula, the British Isles, and the Faroe Islands. For the non-Macaronesian endemic species (F. teneriffae, P. canariensis) higher levels of sex expression and males were found in the Macaronesian archipelagos. In leafy liverworts, females appear to be correlated with lower temperatures and higher precipitation levels, while males seem to be associated with higher temperatures and relatively lower precipitation levels. In this study, we demonstrated that bryophyte populations from Macaronesia exhibited higher levels of sex expression compared to their continental counterparts, suggesting that the distinct environmental conditions of these islands play a crucial role in shaping their reproductive patterns.

Revealing the secrets of Blue Zones

Aging is influenced by cellular senescence mechanisms that are associated with oxidative stress. Oxidative stress is the imbalance between antioxidants and free radicals. This imbalance affects enzyme activities and causes mitochondrial dysfunction. It also slows down cellular energy production and disrupts cellular homeostasis. Additionally, oxidative stress stimulates inflammation, increases the number of point mutations, and alters intercellular communication. It can lead to epigenetic alterations, genomic instability, telomere attrition, and loss of proteostasis. Ultimately, these factors contribute to aging and the development of chronic diseases. Glucose-6-phosphate dehydrogenase (G6PD) is an antioxidant enzyme that protects cells from oxidative and nitrosative damage. It helps restore redox balance, preserve macromolecule function, and rescue cells from cellular senescence, autophagy, and stress-induced apoptosis. G6PD is considered an anti-senescence enzyme. The World Health Organization classifies G6PD variants into five groups based on the enzyme's residual activity. The first four classes are categorized according to the degree of G6PD deficiency, while the fifth class includes variants with enzyme activities greater than normal. Increased G6PD activity does not exhibit clinical manifestations. Consequently, the full spectrum of mutations and the prevalence of increased G6PD activity in the population remain unknown. The world's oldest and healthiest people live in Blue Zones. These comprise isolated populations, and there may be a geographic prevalence of high-activity G6PD variants that protect against oxidative stress-induced senescence. To uncover the secret of centenarians' longevity, additional research is needed to determine whether the hidden factor is the increased activity of the G6PD enzyme.

Unveiling the lifeblood of cities: Identifying urban ecological networks from the perspective of biodiversity conservation

Urban biodiversity faces threats from habitat loss, landscape fragmentation, and human disturbances. Ecological networks (ENs) can enhance habitat connectivity and bolster population resilience to disruptions. To safeguard the biodiversity of Nanjing's urban area, this study selected understory insectivorous birds as indicator species for biodiversity, employing a comprehensive approach integrating the maximum entropy (MaxEnt) model and the area threshold method to delineate ecological source areas. Key indicators directly linked to the species distribution were extracted based on the habitat suitability assessment results, and an ecological resistance surface was crafted using spatial principal component analysis. Subsequently, the circuit theory model was applied to pinpoint ecological corridors, pinch points, and barrier points. The findings unveiled the following: (1) The normalized difference vegetation index (NDVI), human activities (HA), and canopy height (CH) were critical indicators influencing biodiversity. The response curves of the NDVI and CH were positively correlated with the probability distribution of indicator species, while the response curve of the HA showed an overall negative correlation with the same distribution. (2) The spatial distribution characteristics of the ecological network revealed a 'one axis, two cores, intersecting' pattern. Ecological sources were supported by mountainous forests and riverside green spaces, symmetrically distributed on both sides of the Yangtze River. Ecological corridors were forming continuous tree belts along highways and riverways, predominantly concentrated on the eastern side of the Yangtze River. Ecological pinch points and barriers were primarily located at the intersections of fragmented green spaces and developed areas in the northeastern and southeastern regions of the study area. (3) This study finally identified 30 ecological source areas, 65 ecological corridors, 8 pinch points, and 8 barrier points. This study presents a construction paradigm for urban ENs from the vantage point of biodiversity conservation, including both regional specificity and universal applicability, providing vital theoretical underpinnings and pragmatic insights for urban sustainability.

The Secret Family Life of a Group of Golden Jackals on Samos, Greece

The golden jackal (Canis aureus) is remarkably flexible in terms of behaviour. This is advantageous to the range expansion of the species to northern and western Europe. Despite the widespread distribution of the golden jackal, many aspects of its behaviour are still poorly known. In this study, we have aimed to improve our general understanding of golden jackal social behaviour by monitoring one family group of a unique insular population living on Samos (Greece) using camera trap data over a study period of 9 months. Successful identification of individual golden jackals based on visual characteristics, determination of the dominance hierarchy and social network analyses has allowed us to gain insights into the group's social organisation, mating system and social structure determined by social relationships. We revealed the studied family group to be relatively stable, consisting of a dominant adult pair and one or two generations of their offspring. Some major changes occurred during the breeding season in terms of social behaviour, group composition and structure. A total of six pups were born, which were cared for by both dominant adults as well as one male and one female yearling who stayed as helpers at the nest. Both the dominant female and the female yearling showed signs of lactation, suggesting either a case of pseudopregnancy or allonursing. Using non-invasive methods combined with individual identification based on coat colouration patterns, this research contributes to our understanding of the social behaviour of the golden jackal population on Samos in Europe and, by extension, of the species as a whole.

Inter and intra-island genetic structure and differentiation of the endemic Bolle's Laurel Pigeon (Columba bollii) in the Canary archipelago

Islands provide excellent settings for studying the evolutionary history of species, since their geographic isolation and relatively small size limit gene flow between populations, and promote divergence and speciation. The endemic Bolle's Laurel Pigeon Columba bollii is an arboreal frugivorous bird species distributed on laurel forests in four islands of the Canary archipelago. To elucidate the population genetics, we genotyped ten microsatellite loci using DNA obtained from non-invasive samples collected across practically all laurel forest remnants, and subsequently grouped into eight sampling sites. Analyses including F-statistics, Bayesian clustering approaches, isolation by distance tests and population graph topologies, were used to infer the genetic diversity and the population differentiation within and among insular populations. Additionally, we evaluated the effect of null alleles on data analysis. Low genetic diversity was found in all populations of Bolle's Laurel Pigeon, with no significant differences in diversity among them. However, significant genetic differentiation was detected among all populations, with pigeons from La Palma and El Hierro exhibiting the closest affinity. Bayesian clustering supported population separation between islands, and also detected fine-scale structure within the Tenerife and La Gomera populations. Our results suggest that, despite columbids have a high movement ability, they can show signature of genetic divergence among populations, particularly on oceanic islands. Geological history of the islands and distribution range of habitats could have close influence on the evolutionary trajectories of these birds. This approach can provide practical tools to implement appropriate conservation measures for range-restricted species and their habitat.

Unlocking the tapestry of conservation: Navigating ecological resettlement policies in Nepal

Conservation initiatives involve a complex interplay of various ecological, socio-political, and economic factors. Ecological resettlement (ER), implemented within the context of nature conservation policies, stands as one of the most contested issues worldwide. This study aims to navigate the domain of ER policy in conservation through discursive institutionalism and a policy arrangement approach. Focusing on Nepal's conservation policy pathways over the last seven decades, we critically analyze policy ideas and narratives, trends, patterns of policy development, institutional arrangements, driving factors, and responses to contemporary ER policies. Methods involved a systematic literature review (n = 271), a comprehensive review of policy documents and project reports (n > 150), and expert interviews (n = 20). Over the past 50 years, >7600 households in Nepal have been displaced in the name of ER and are still persisting despite the rhetoric of participatory conservation. With changes in political regimes, conservation policy has shifted from a hunting-focused approach to landscape-level and transboundary conservation. Initially influenced by internal factors such as economic and political governance, conservation policies were later shaped by international conservation discourse. Also, the operational sphere of such policy ideas and narratives - including actors, resources, discourses, and rules - along with trends, priorities, institutional arrangements, and driving factors of ER policies, has changed over time. Further, the exclusion of deprived communities and the capture of conservation benefits by elites have undermined conservation values. This research stresses the importance of a judicious balance between people's welfare and nature's integrity, emphasizing community-based natural resource management models accredited to a conservation standard. We further urge the revision of displacement-oriented conservation policies to secure the rights of Indigenous people and traditional landholders, thereby ensuring conservation and sustainable development at both national and global levels.

Local and regional processes drive distance decay in structure in a spatial multilayer plant-pollinator network

Understanding spatial variation in species distribution and community structure is at the core of community ecology. Nevertheless, the effect of distance on metacommunity structure remains little studied. We examine how plant-pollinator community structure changes across geographical distances at a regional scale and disentangle its underlying local and regional processes. We use a multilayer network to represent linked plant-pollinator communities as a metacommunity in the Canary Islands. We used modularity (i.e. the extent to which the community is partitioned into groups of densely interacting species) to quantify distance decay in structure across space. In multilayer modularity, the same species can belong to different modules in different communities, and modules can span communities. This enabled quantifying how similarity in module composition varied with distance between islands. We developed three null models, each controlling for a separate component of the multilayer network, to disentangle the role of species turnover, interaction rewiring and local factors in driving distance decay in structure. We found a pattern of distance decay in structure, indicating that islands tended to share fewer modules with increasing distance. Species turnover (but not interaction rewiring) was the primary regional process triggering distance decay in structure. Local interaction structure also played an essential role in determining the structure similarity of communities at a regional scale. Therefore, local factors that determine species interactions occurring at a local scale drive distance decay in structure at a regional scale. Our work highlights the interplay between local and regional processes underlying community structure. The methodology, and specifically the null models, we developed provides a general framework for linking communities in space and testing different hypotheses regarding the factors generating spatial structure.

Speciation happens in company - not in isolation

Oceanic islands are considered the classic arenas for allopatric speciation and adaptive radiation. Established concepts of speciation and endemism are strongly focused on spatial and temporal scales. However, biotic interactions and ecological drivers, although widely recognized as playing a role, still need to be integrated into our understanding of these processes. Here, I highlight ecosystems as the evolutionary arena within islands. Ecosystem functioning, such as the regulation of abiotic fluxes of energy and matter, has been intensely studied in the context of climate change and biodiversity loss. Biogeography, on the other hand, when it focuses on speciation and endemism, often lacks a functional understanding of the ecosystem beyond species lists. This contribution aims to stimulate a stronger integration of ecological processes, assembly rules, and vegetation structures into future biogeographical and macroecological studies.

New World dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) colonization of a recent Miocene insular territory: The case of Costa Rica

Costa Rica emerged from the seas as a new geological territory during the Miocene as an insular archipelago. It later became part of a continental area once it became a segment of Central America. Two dung beetle genera that colonized this new territory from South and North America, Canthidium and Onthophagus (Coleoptera: Scarabaeidae: Scarabaeinae), are here studied, in the first analysis of a volcanic paleo-archipelago, colonized from its emergence, and then later becoming terra firma. To assess their biodiversity distribution patterns, we analyzed the effect of biogeography, ecosystem origins, and body size on their altitudinal distribution patterns in three geographic basins of Costa Rica. Based on 32 years of collecting representing more than 158,000 specimens from 1017 localities, we undertook Generalized Linear Models of the two dung beetle genera to assess the effects of biodiversity and biogeographical distribution patterns. Canthidium and Onthophagus species ranged from 0 to 3000 m a.s.l., with an abrupt diversity decline at altitudes above 1500 m. Endemic species tended to show a higher altitudinal mean with a narrow altitudinal band distribution than non-endemic dung beetle species. Although there was a trend of decreasing species body size with the increase in altitude, such a trend depended on the distribution pattern of the species group. This possible insular-mediated endemicity mechanism has generated baffling biodiversity levels, considered the highest worldwide per unit area. Costa Rica is an expanse represented by a geographic overlap of two or more temporally disjunct areas and is not part of a natural transition zone. The effect of the insular Miocene origin of Costa Rica still pervades today, reflected by different insular syndromes shown by the dung beetle fauna. The importance of geological origins in generating biodiversity seems to have been an underrated criterion for conservation biology practices and should be considered ex officio.

Non-native ants are breaking down biogeographic boundaries and homogenizing community assemblages

As geographic distance increases, species assemblages become more distinct, defining global biogeographic realms with abrupt biogeographic boundaries. Yet, it remains largely unknown to what extent these realms may change because of human-mediated dispersal of species. Focusing on the distributions of 309 non-native ant species, we show that historical biogeographic patterns have already broken down into tropical versus non-tropical regions. Importantly, we demonstrate that these profound changes are not limited to the distribution patterns of non-native ants but fundamentally alter biogeographic boundaries of all ant biodiversity (13,774 species). In total, 52% of ant assemblages have become more similar, supporting a global trend of biotic homogenization. Strikingly, this trend was strongest on islands and in the tropics, which harbor some of the most vulnerable ecosystems. Overall, we show that the pervasive anthropogenic impacts on biodiversity override biogeographic patterns resulting from millions of years of evolution, and disproportionally affect particular regions.

Diversification of freshwater crabs on the sky islands in the Hengduan Mountains Region, China

The numerous naturally-fragmented sky islands (SIs) in the Hengduan Mountains Region (HMR) of southwestern China constitute discontinuous landscapes where montane habitats are isolated by dry-hot valleys which have fostered exceptional species diversification and endemicity. However, studies documenting the crucial role of SI on the speciation dynamics of native freshwater organisms are scarce. Here we used a novel set of comprehensive genetic markers (24 nuclear DNA sequences and complete mitogenomes), morphological characters, and biogeographical information to reveal the evolutionary history and speciation mechanisms of a group of small-bodied montane potamids in the genus Tenuipotamon. Our results provide a robustly supported phylogeny, and suggest that the vicariance events of these montane crabs correlate well with the emergence of SIs due to the uplift of the HMR during the Late Oligocene. Furthermore, ancestrally, mountain ridges provided corridors for the dispersal of these montane crabs that led to the colonization of moist montane-specific habitats, aided by past climatic conditions that were the crucial determinants of their evolutionary history. The present results illustrated that the mechanisms isolating SIs are reinforced by the harsh-dry isolating climatic features of dry-hot valleys separating SIs and continue to affect local diversification. This offers insights into the causes of the high biodiversity and endemism shown by the freshwater crabs of the HMR-SIs in southwestern China.

Ecological network construction and optimization in Guangzhou from the perspective of biodiversity conservation

Rapid urbanization has resulted in fragmentation and decreased connectivity in urban landscapes, endangering regional biodiversity conservation and high-quality, sustainable development. networks (ENs) construction and optimization is a critical technique to enhance landscape connectivity effectively, promote species interaction and dispersal, and thereby hence urban biodiversity., most existing studies on ENs construction have been undertaken from the perspective of ecosystem service functions or the value of landscape structure, with regional species still being overlooked. on the distribution data of critical species in this study, the maximum entropy model (MaxEnt), wilderness mapping model, and granularity reverse method were integrated to identify ecological sources. the habitat quality (HQ) index was utilized to construct a resistance surface modified by landscape connectivity and ecological sensitivity. findings indicate that: (1) a grid scale of 1700 m is the relatively optimal minimum threshold for ecological source sites in Guangzhou; (2) 35 crucial ecological sources in Guangzhou are identified, with a total area of 1100.42 km², mainly woodlands, distributed in mountain systems in the northern and central parts of the city; and (3) 59 ecological corridors are identified, with a total length of 817.4 km, with a relatively high density in the central part of the city. some extent, this study offers fresh ideas for constructing urban ENs from the standpoint of biodiversity conservation. contributes to the city achieving a win-win economic development and ecological protection situation.