Skink Species Research Articles

Dances with wolves: The demographic consequence of asymmetric competition and intraguild predation in a native‐invasive skink system

Abstract Currently, we lack enough knowledge to fully explain how the impacts of species invasion on native communities are attributed to multifaceted, individual‐based behavioural outcomes. Here, we illustrate the long‐term population dynamics of the native long‐tailed sun skink (Eutropis longicaudata) before and after the invasion of the common sun skink (Eutropis multifasciata). We conducted diet investigation, morphological measurement, and a series of behavioural experiments both in the field and laboratory. We explained how the impacts of the invasive skink on the native skink can cascade towards the population level based on these individual‐level behavioural data. We present evidence of competition exclusion of the native skink population resulting from the invasion of the common sun skink. The drastic decline found in the native skink population was largely accounted for by low recruitment, as shown by the decrease in its clutch numbers correspondingly. We also found dominance of the invasive skink in both exploitation competition and intraguild predation. Considering the highly overlapping morphological and dietary niches between the two species, our findings imply that the native skink has undergone strong food competition and predation pressure on its eggs and juveniles. Interestingly, the native skink started to display parental care behaviour 2 years after the invasion event, and its clutch survival rate has recovered since then. The shift in parental care behaviour may help the native skink cope with this new predation pressure from the invasive skink. Overall, the two competitive skinks showed low chances of coexisting. The negative population growth of this native skink species may be primarily derived from poor reproductive performance, given a sharp decline in its clutch numbers and its inferiority in exploitation competition, despite rebounding clutch survival rates. Read the free Plain Language Summary for this article on the Journal blog.

Skinks of Oceania, New Guinea, and Eastern Wallacea: an underexplored biodiversity hotspot

Context Skinks comprise the dominant component of the terrestrial vertebrate fauna in Oceania, New Guinea, and Eastern Wallacea (ONGEW). However, knowledge of their diversity is incomplete, and their conservation needs are poorly understood. Aims To explore the diversity and threat status of the skinks of ONGEW and identify knowledge gaps and conservation needs. Methods We compiled a list of all skink species occurring in the region and their threat categories designated by the International Union for Conservation of Nature. We used available genetic sequences deposited in the National Center for Biotechnology Information’s GenBank to generate a phylogeny of the region’s skinks. We then assessed their diversity within geographical sub-divisions and compared to other reptile taxa in the region. Key results Approximately 300 species of skinks occur in ONGEW, making it the second largest global hotspot of skink diversity following Australia. Many phylogenetic relationships remain unresolved, and many species and genera are in need of taxonomic revision. One in five species are threatened with extinction, a higher proportion than almost all reptile families in the region. Conclusions ONGEW contain a large proportion of global skink diversity on <1% of the Earth’s landmass. Many are endemic and face risks such as habitat loss and invasive predators. Yet, little is known about them, and many species require taxonomic revision and threat level re-assessment. Implications The skinks of ONGEW are a diverse yet underexplored group of terrestrial vertebrates, with many species likely facing extreme risks in the near future. Further research is needed to understand the threats they face and how to protect them.

Testing Drones as a Tool for Surveying Lizards

A lack of effective methods for sampling lizards in terrain that is inaccessible to human observers limits our knowledge of their ecology and conservation needs. Drones are increasingly being used in wildlife monitoring, but their potential use for surveying lizards has not been evaluated. We investigated: (1) the detectability of model lizards using a drone relative to a human observer, and (2) the response of four lizard species to an approaching drone in three habitat types. Model lizards placed in potential basking positions within a defined search area were detected by both the drone operator and human observer, but the probability of detection was lower with the drone. Jewelled geckos (Naultinus gemmeus) in shrubland and grand skinks (Oligosoma grande) in rocky habitats showed surprisingly little reaction to the approaching drone, enabling close approaches (means of 59 cm and 107 cm, respectively) and accurate species identification with photos taken by the drone camera. For highly patterned jewelled geckos, identification was also possible to individual level. However, the drone was unsuccessful at detecting two alpine skink species in a near-vertical cliff habitat. Collectively, our results suggest that drones have potential as a tool for detecting small-bodied lizards in habitats inaccessible to human observers.

A new lizard species (Scincidae: Ctenotus) highlights persistent knowledge gaps on the biodiversity of Australia’s central deserts

Australia harbors the most diverse lizard assemblages on Earth, yet the biodiversity of its vast arid zone remains incompletely characterized. Recent sampling of remote regions has revealed new species with unique phenotypes and unclear evolutionary affinities. Here, we describe a new species of scincid lizard that appears to be widely distributed across the Great Victoria Desert and adjacent regions. The new species was previously overlooked among specimens of the wide-ranging desert taxon Ctenotus schomburgkii but is distinguished from it by coloration and scalation characters. Phylogenetic analyses based on mitochondrial and genome-wide nuclear loci confirmed that the new species is highly divergent from C. schomburgkii, with which it appears to be sympatric across much of its range. In addition to the new species, our survey of genetic variation within C. schomburgkii as currently recognized revealed three additional lineages that approach one another in southern and northwestern Australia, and which may also represent distinct species. These results suggest that our knowledge of the extraordinary biodiversity of arid Australia remains incomplete, with implications for the conservation and management of this unique fauna. The targeted collection of voucher specimens in undersampled regions, coupled with population genetic screening of lineage diversity, will be crucial for characterizing species boundaries and understanding the composition of Australia’s vertebrate communities.

Diet of Five Trachylepis Skink Species (Scincidae: Mabuyinae) in Savanna Biome of Namibia

Lizards, especially skinks (Scincidae) occurring in arid environments constitute good study objects to test niche differentiation and other related issues of interspecific competition. Diet of five Trachylepis skink (T. punctulata, T. binotata, T. capensis, T. wahlbergii, T. damarana) was studied through stomach content analysis. Skinks were collected in savanna habitats in Namibia. In all these species, active foraging strategy predominates. All skink species preyed almost exclusively on insects. Four insect taxa comprised the bulk of diet in all five species investigated: Coleoptera, Orthoptera, Isoptera, Hymenoptera (Formicidae) and larvae. Their overall contribution ranged from 72.2% to 100.0% of all prey items in the diet of particular skink species. Most prey items were below 10 mm long, some were 11-20 mm in length. Both males and females fed on the same prey groups, but there were marked differences in the proportions of these groups. In general, males preyed more on beetles and grasshoppers, while females – more on ants. All main prey groups were recorded both in dry and in wet season in all five skink species. Food niche overlap was the highest between T. damarana and T. wahlbergii (0.84), and between T. binotata and T. punctulata (0.77). No overlap in food niche was recorded between T. capensis and T. punctulata, and low overlap (0.26) between T. capensis and T. binotata.

A database of the morphology, ecology and literature of the world's limb‐reduced skinks

AbstractAimLimb‐reduced squamates are a convenient model system to investigate macroevolutionary trends in morphology. Here, we provide morphological, ecological and literature data on all known species of limb‐reduced skinks (Scincidae) and their relatives, representing one of the most diverse and widely distributed groups of limb‐reduced squamates.LocationGlobal.TaxonSkinks (Reptilia, Squamata: Scincidae). Limb‐reduced forms.MethodsMorphological data were sourced from the primary literature, spanning a period of over 150 years. Linear body measurements were averaged across all values in the literature, preserving proportionality to body length. For digits and presacral vertebrae, we used maximum recorded counts. Ecological and biogeographical data were sourced from habitat assessments in the primary literature, online databases and field guides. Literature data were sorted according to type of study. To exemplify the applicability of the database, we used Markov‐chain ordered models to estimate the evolutionary frequency of limb reduction and loss in skinks.ResultsWe find evidence of limb reduction and loss in a total of 394 species worldwide, representing ~23% of all skink species, and ~30% of genera. The distribution of limb‐reduced and limbless forms differs from that of fully limbed forms, as they are present in all biogeographic realms with the almost complete exclusion of the Americas. We estimate that limb reduction evolved more than 50 times in skinks, and that loss of at least one limb pair evolved at least 24 times.Main conclusionsThe dataset captures a broad spectrum of morphological and ecological variation in a large, globally distributed taxonomic group. It establishes a widely applicable definition of limb reduction based on limb proportions as a reference for future studies. Such an extensive collection of morphological and ecological data can pave the way for investigations of dramatic morphological transitions and their ecological drivers at a global and local scale.

The Terrific Skink bite force suggests insularity as a likely driver to exceptional resource use

Natural history museum collections hold extremely rare, extinct species often described from a single known specimen. On occasions, rediscoveries open new opportunities to understand selective forces acting on phenotypic traits. Recent rediscovery of few individuals of Bocourt´s Terrific Skink Phoboscincus bocourti, from a small and remote islet in New Caledonia allowed to genetically identify a species of land crab in its diet. To explore this further, we CT- and MRI-scanned the head of the holotype, the only preserved specimen dated to about 1870, segmented the adductor muscles of the jaw and bones, and estimated bite force through biomechanical models. These data were compared with those gathered for 332 specimens belonging to 44 other skink species. Thereafter we recorded the maximum force needed to generate mechanical failure of the exoskeleton of a crab specimen. The bite force is greater than the prey hardness, suggesting that predation on hard-shelled crabs may be an important driver of performance. The high bite force seems crucial to overcome low or seasonal variations in resource availability in these extreme insular environments. Phoboscincus bocourti appears to be an apex predator in a remote and harsh environment and the only skink known to predate on hard-shelled land crabs.

Invasive ants reduce abundance of small rainforest skinks

Invasive ants are among the world’s most damaging invasive species, often directly or indirectly affecting native fauna. Insecticidal baits are the main method for suppressing or eradicating invasive ant populations, but their use must be considered against potential for unintended effects on native organisms. The invasive yellow crazy ant (Anoplolepis gracillipes) is widespread in the tropics, particularly on islands, where they have displaced a range of invertebrates. Effects of this ant on vertebrates, and in continental ecosystems generally, are less studied. We investigated the effects of yellow crazy ants and bait application on rainforest skinks and their invertebrate prey. We compared skink and skink prey abundance across four replicated rainforest site categories: high and low yellow crazy ant sites had both been baited but differed in yellow crazy ant activity; control sites had never had yellow crazy ants or been baited; and buffer sites had never had yellow crazy ants but had been baited. We recorded significantly lower abundance of two small skink species (Lygisaurus laevis and Saproscincus tetradactylus) in high yellow crazy ant sites compared to all other site categories. The differences persisted even after baiting reduced yellow crazy ant activity by 97.8% ± 0.04% (mean ± SD). A larger rainforest skink species (Carlia rubrigularis) was not negatively affected by yellow crazy ant invasion. Skink prey abundance was significantly lower in high yellow crazy ant sites compared to control sites and low yellow crazy ant sites, but not compared to buffer sites. These differences did not persist following baiting. We found no evidence that baiting negatively affects skinks or their invertebrate prey. Our data suggest that yellow crazy ants, but not the bait used to treat them, pose a direct threat to small rainforest skinks.

Characterisation and cross-amplification of sex-specific genetic markers in Australasian Egerniinae lizards and their implications for understanding the evolution of sex determination and social complexity

Sex is a pervasive factor that underpins functional phenotypic variation across a range of traits. Although sex can usually be distinguished morphologically, in some species this is not possible. The development of genetic markers for sex identification is, thus, key if we are to incorporate sex into an understanding of ecological or evolutionary process. Here we develop genetic markers for the identification of sex within an iconic Australian lizard group, the Egernia group, which is notable for its complex social behaviour. We used restriction-site associated DNA sequencing to characterise sex-specific genetic sequences for a key member of the group, Liopholis whitii, and designed primers for four of these putative sex-specific sequences. These primers amplified across some, but not all, species of the group. Our results provided several important insights. They suggest conservatism of a XX/XY sex determination system within the group as well as sex-specific genomic regions that appear independent of the conserved genomic regions identified in other skink species. More broadly, the development of sex markers for the Egernia group opens up a range of potential research questions related to the role that sex plays in the mediation of social behaviour and, through this, the emergence and stability of social life.

Predictors of geographic range size in Australian skinks

AbstractAimGeographic range size varies greatly across species. Climate, along with aspects of a species’ biology, may influence its spatial extent. We investigate intrinsic and extrinsic predictors of range size in Australian skinks. We predicted that larger body size, longer limbs, and larger clutch sizes would be associated with larger ranges, and that ranges would be larger in colder, more arid, and more seasonal climates.LocationMainland Australia.TaxonSkinks (Scincidae).MethodsWe test for climatic and geographic correlates of range size of Australian skink species (417 of 462 described species), as well as investigate the effects of body size and clutch size (259 species). We compare detailed morphological measurements of 1,324 specimens across nine pairs of widespread and narrow‐ranged congeneric species to investigate the roles of intrinsic (body size, clutch size, morphology) and extrinsic (mean temperature and precipitation) factors in determining range size.ResultsIn the broader analysis, large range sizes were associated with the presence of fully developed limbs, low precipitation seasonality, high temperatures, and high precipitation. Ranges of species traversing the Great Dividing Range are larger by an order of magnitude than those east of the range, with western ranges being intermediate. Affinity to specific biomes explained less variation than climatic variables. For the nine species pairs, wide‐ranging species share similar morphologies and clutch sizes with overlapping narrow‐ranging congeners, but generally inhabit more arid regions.Main conclusionsWe found several extrinsic, but few intrinsic, factors were correlated with range size. The narrow mesic belts in Australia compared with the extensive expanse of arid and semi‐arid regions may explain why desert species have larger ranges. This interpretation agrees with the notion that the size of the domain, here a climatic domain rather than a physical one, may exert strong influence on species’ range sizes.

Skinks in Zoos: A global approach on distribution patterns of threatened Scincidae in zoological institutions

To manage populations of threatened species according to the IUCN’s One Plan Approach, knowledge about both in situ and ex situ populations is required. To enhance the conservation of threatened skinks and to gain an overview which skink species are kept in zoos, and thus already have an ex situ conservation component, we analysed data from the Zoological Information Management System (ZIMS): their individual numbers, breeding success, and the number of holding institutions. We categorised species as threatened or non-threatened based on IUCN Red List assessments. Only 92 (~5%) of 1727 recognized skink species are held in ZIMS institutions worldwide, mostly in Australia, Europe, and North America. 77% of the species kept globally are classified as non-threatened and ~23% (21 species) are threatened. Only 28% of the species kept have successfully bred in the last year, mostly in one zoo each. Of these seven species were threatened. All threatened species are kept by four zoos at most, generally only in one. Half of the skink species kept are represented by less than 10 individuals. Mainly Australian skink species were kept. To improve the conservation of threatened skinks, a shift towards keeping threatened species should be considered within captive management programmes. European and North American zoos offer capacities and expertise for skink conservation but are outside skink species richness hotspots. Cooperative projects with institutions and stations in such hotspots could greatly benefit the conservation of skinks. Thus, according to the One Plan Approach, the ex situ populations could directly contribute to in situ protection.

Cytogenetically Elusive Sex Chromosomes in Scincoidean Lizards.

The lizards of the species-rich clade Scincoidea including cordylids, gerrhosaurids, skinks, and xantusiids, show an almost cosmopolitan geographical distribution and a remarkable ecological and morphological divergence. However, previous studies revealed limited variability in cytogenetic traits. The sex determination mode was revealed only in a handful of gerrhosaurid, skink, and xantusiid species, which demonstrated either ZZ/ZW or XX/XY sex chromosomes. In this study, we explored the karyotypes of six species of skinks, two species of cordylids, and one gerrhosaurid. We applied conventional and molecular cytogenetic methods, including C-banding, fluorescence in situ hybridization with probes specific for telomeric motifs and rDNA loci, and comparative genomic hybridization. The diploid chromosome numbers are rather conserved among these species, but the chromosome morphology, the presence of interstitial telomeric sequences, and the topology of rDNA loci vary significantly. Notably, XX/XY sex chromosomes were identified only in Tiliqua scincoides, where, in contrast to the X chromosome, the Y chromosome lacks accumulations of rDNA loci. We confirm that within the lizards of the scincoidean clade, sex chromosomes remained in a generally poor stage of differentiation.

Conservation status of the world's skinks (Scincidae): Taxonomic and geographic patterns in extinction risk

Our knowledge of the conservation status of reptiles, the most diverse class of terrestrial vertebrates, has improved dramatically over the past decade, but still lags behind that of the other tetrapod groups. Here, we conduct the first comprehensive evaluation (~92% of the world's ~1714 described species) of the conservation status of skinks (Scincidae), a speciose reptile family with a worldwide distribution. Using International Union for Conservation of Nature (IUCN) criteria, we report that ~20% of species are threatened with extinction, and nine species are Extinct or Extinct in the Wild. The highest levels of threat are evident in Madagascar and the Neotropics, and in the subfamilies Mabuyinae, Eugongylinae and Scincinae. The vast majority of threatened skink species were listed based primarily on their small geographic ranges (Criterion B, 83%; Criterion D2, 13%). Although the population trend of 42% of species was stable, 14% have declining populations. The key threats to skinks are habitat loss due to agriculture, invasive species, and biological resource use (e.g., hunting, timber harvesting). The distributions of 61% of species do not overlap with protected areas. Despite our improved knowledge of the conservation status of the world's skinks, 8% of species remain to be assessed, and 14% are listed as Data Deficient. The conservation status of almost a quarter of the world's skink species thus remains unknown. We use our updated knowledge of the conservation status of the group to develop and outline the priorities for the conservation assessment and management of the world's skink species.

A new species of Sun Skink (Reptilia: Scincidae: Eutropis) from the Zamboanga Peninsula, southwestern Mindanao Island, Philippines

We describe a new species of lizard in the genus Eutropis Fitzinger 1843 from the southwestern tip of the Zamboanga Peninsula on the western part of Mindanao Island, Philippines. The new species is related to Eutropis rugifera, which is a secretive, forest-adapted skink that ranges widely outside the Philippines from the western extent of its distribution on Nicobar Island (the type locality) through southern Peninsular Malaysia, Sumatra, and the Mentawai islands, Borneo, Java, and as far east as Bali Island. The discovery of a new, morphologically distinct, and genetically highly divergent Sun Skink lineage in the low elevation forests of the Zamboanga Peninsula creates a puzzling disjunct geographic distribution (E. rugifera has not been reported from the Sulu Archipelago). The new species is estimated to have diverged ~10–16 mya from E. rugifera, from which it appears to have an extralimital and isolated distribution. Considering the dynamic geological history and ancient continental origin of the Zamboanga Peninsula, colonization by the new species may have been facilitated by pre-Pleistocene overseas long-distance dispersal, saltatory range expansion, and subsequent contraction/extinction in the Sulu Archipelago, and/or possibly paleotransport on the ancient crustal fragment of Zamboanga. The new species is known only from Zamboanga City’s primary surface water supply catchment at the lowest elevations inside the boundaries of Pasonanca Natural Park, despite the fact that there have been historical surveys of herpetological diversity at multiple sites to the northeast (Zamboanga, western Mindanao) and to the southwest (Sulu Archipelago). The new species, thus, may be limited to just the tip of the Zamboanga Peninsula, possibly rendering KEYWORDS: IUCN Red List, Palawan microcontinent block, Pasonanca Natural Park, Sulu Archipelago, Surface catchment watershed biodiversity

A new species of Asian gracile skink (Scincidae: Lygosominae: emSubdoluseps/em) from the rain-shadow belts of Nilgiri hills, Western Ghats, India.

We describe a new species of Asian gracile skink from the dry leeward slopes of the Nilgiri hills, Tamil Nadu state, India which forms a part of the eastern, rain shadow escarpment of the Western Ghats in peninsular India. The new species, Subdoluseps nilgiriensis sp. nov., is characterized by: slender, small-sized body (47-67 mm); sandy brown above, with each scale tipped with black; a thick black lateral band from snout to tail; a distinct white labial streak; dirty white venter, with throat having mild black striations; 28-29 midbody scale rows; 71-74 mid ventral scales; 66-69 paravertebral scales. The new species is described based on external morphological characters, genetic data and geographical isolation. Based on two mitochondrial DNA genes, we show that the new species shares a sister relationship with Subdoluseps pruthi (Sharma, 1977) which is found in parts of the Eastern Ghats in peninsular India. The discovery of this new population raises two novel scenarios. Firstly, it renders the genus Subdoluseps evolutionarily polyphyletic with respect to the Indian species included in this genus. Secondly, it falsifies the notion that S. pruthi group skinks are restricted to the Eastern Ghats. Our results further indicate that the dry zone of peninsular India has unrealized skink diversity that needs to be further explored.

Elevation is a stronger predictor of morphological trait divergence than competition in a radiation of tropical lizards.

Adaptations for efficient performance are expected to shape animal morphology based on selection for microhabitat use and ecological forces. The presence of competitor species is predicted to cause niches to contract and enhance trait divergence. Therefore, increased species richness is expected to lead to greater trait divergence, and to result in reduced overlap and similarity between morphologies of sympatric species. We examined patterns of morphospace occupancy and partitioning in the skink fauna of New Guinea, the world's largest tropical island. Because skink species richness is largely decoupled from elevation in New Guinea, we could examine the effects of both factors (as proxies for competition and abiotic conditions), on morphospace occupancy and partitioning. We measured 1,860 specimens from 79 species of skinks throughout Papua New Guinea, and examined their morphospace occupancy in a spatial context. We calculated, for each assemblage within equal-area cells, the volume of morphospace occupied by all skinks, the mean volume occupied per species, and the mean distance and overlap between all species pairs. We then examined whether these metrics are related to species richness and elevation. Elevation is a stronger predictor of morphospace occupancy than species richness. As elevation increases, intraspecific variation decreases and morphologies become more similar to each other such that overall morphospace occupancy decreases. Highland skinks are, on average, smaller, thinner and shorter limbed than lowland species. We hypothesise that harsh climates in the New Guinea highland habitats impose strong selection on skinks to occupy specific areas of morphospace that facilitate efficient thermoregulation in suboptimal thermal conditions. We conclude that the effect of competition on trait divergence on a community and assemblage scale is eclipsed by abiotic selection pressures in these harsh environments.

Thành phần thức ăn của Thằn lằn chân ngắn Subdoluseps (Squamata: Scincidae) ở phía Nam Việt Nam

Currently, two species of the Asian Agile skinks genus Subdoluseps, including S. bowringii and S. vietnamensis, occur in Vietnam. The former is widely distributed throughout the country while the later has been recorded in the coastal areas of Binh Thuan and Ba Ria-Vung Tau provinces. Analyses of 46 stomach samples of the S. bowringii and 39 stomach samples of S. vietnamensis collected at 17 locations in southern Vietnam resulted in recording of 17 food groups of six classes of Invertebrates and one class of Vertebrate animals. Two skinks share 9 of 17 common food groups (52.9%). The Insecta class dominated with 8/17 groups (47.1%) observed. Among the Insecta, Blattodea order occupied the highest percentage and followed by Coleoptera, Dermaptera orders, and insect larvae. The Araneae, Scolopendromorpha, Squamata, and Isopoda orders are also prioritized by these two species. Subdoluseps bowringii eats 14 food groups, the Insecta class dominates with 7/14 groups (50%) with the Blattodea order being the highest frequency (63.0%). The S. vietnamensis eats 12 food groups, the Insecta class dominates with 5/12 groups (41.7%) with the Blattodea order being the highest frequency (74.4%). In addition to animals, other components such as soil (2.2%) and leaves (2.6%) were also recorded in the stomachs of the two species.

Does the invasive plague skink (Lampropholis delicata) compete with native skink species in New Zealand?

AbstractInvasive species are a major threat to biodiversity worldwide, causing many of the recent declines and extinctions of native species. Competition is a common mechanism through which invasive species impact the native biota. In particular, exploitative competition results when the invader outcompetes native species for essential resources, such as food and shelter sites. Despite being pervasive invaders, the ecological impacts of invasive lizards are understudied and it is often unknown whether these invaders have detrimental impacts. The plague skink (Lampropholis delicata), native to eastern Australia, has invaded several locations throughout the Pacific region (Hawaiian Islands, New Zealand, Lord Howe Island). However, no studies have documented the plague skink as having a negative impact on native species anywhere throughout its introduced range. Here, we conducted a mark‐recapture study in northern New Zealand (Shakespear Regional Park) to investigate whether the plague skink competes with native skink species (Oligosoma aeneum, O. ornatum, O. moco). Though the plague skink has a broader distribution within the study region and occurred across a broader range of habitats, there was substantial range and niche overlap between the plague skink and the three native skink species. Both the absolute capture rates and estimated population size of the plague skink were significantly higher than the three native skink species. Although plague skinks have smaller body sizes well as shorter and narrower heads than the native skink species, there was still considerable scope for dietary overlap among the species. While our study does not provide definitive evidence for competition between the plague skink and native skink species in New Zealand, we clearly demonstrate the presence of the core components required for exploitative competition to occur. Further field‐ and laboratory‐based studies will be required to confirm the existence of exploitative or interference competition by the plague skink in its introduced range.

Compartmentalized organization of ecological niche occupation in insular invertebrate communities.

Understanding the mechanisms of species distribution within ecosystems is a fundamental question of ecological research. The current worldwide changes and loss of habitats associated with a decline in species richness render this topic a key element for developing mitigation strategies. Ecological niche theory is a widely accepted concept to describe species distribution along environmental gradients where each taxon occupies its own distinct set of environmental parameters, that is, its niche. Niche occupation has been described in empirical studies for different closely related taxa, like ant, ungulate, or skink species, just to name a few. However, how species assemblages of whole ecosystems across multiple taxa are structured and organized has not been investigated thoroughly, although considering all taxa of a community would be essential when analyzing realized niches. Here, we investigated the organization of niche occupation and species distribution for the whole ground‐associated invertebrate community of small tropical insular ecosystems. By correlating environmental conditions with species occurrences using partial canonical correspondence analysis (pCCA), we demonstrated that the ground‐associated invertebrate community does not spread evenly across the overall niche space, but instead is compartmentalized in four distinct clusters: crustacean and gastropod taxa occurred in one cluster, attributable to the beach habitat, whereas hexapods and spider taxa occurred in three distinct inland clusters, attributable to distinct inland habitats, that is, grassland, open forest, and dense forest. Within the clusters, co‐occurrence pattern analysis suggested only a few negative interactions between the different taxa. By studying ground‐associated insular invertebrate communities, we have shown that species distribution and niche occupation can be, similar to food webs, organized in a compartmentalized way. The compartmentalization of the niche space might thereby be a mechanism to increase ecosystem resilience, as disturbances cascade more slowly throughout the ecosystem.

A new species of Trachylepis (Squamata: Scincidae) from the Amhara Region, Ethiopia, and a key to the Ethiopian Trachylepis.

Ethiopia is known for its highly endemic and rich herpetofaunal diversity shaped by its biogeographical patterns. Here, a new species of skink, Trachylepis boehmei sp. nov., is described from the Ethiopian Highlands. It differs from its congeners in having smooth uncarinated dorsal scales, 26-29 scale rows around midbody, a slender body of small size, a relatively short tail, a low eye-snout distance and a unique colour pattern with 6-8 darkish brown dorsal stripes. Based on morphological characteristics, its biogeographical pattern and comparisons with other similar congeners this new species is closely related to Trachylepis megalura. A published new record of Trachylepis wingati for the Kafa region is re-examined and identified as T. megalura. An updated comprehensive key to the Trachylepis found in Ethiopia is provided. In the context of ongoing phylogenetic and taxonomic revisions of Trachylepis and its species complexes the presence of further cryptic taxa can be expected also for the Ethiopian biodiversity hotspots. Consequently, the need of further herpetological investigations in this region of ecological importance is stressed.