Ecological Rarity Research Articles

Modelling reveals the effect of climate and land use change on Madagascar’s chameleons fauna

The global biodiversity crisis is generated by the combined effects of human-induced climate change and land conversion. Madagascar is one of the World’s most renewed hotspots of biodiversity. Yet, its rich variety of plant and animal species is threatened by deforestation and climate change. Predicting the future of Madagascar’s chameleons, in particular, is complicated by their ecological rarity, making it hard to tell which factor is the most menacing to their survival. By applying an extension of the ENphylo species distribution model algorithm to work with extremely rare species, we find that Madagascar chameleons will face intense species loss in the north-western sector of the island. Land conversion by humans will drive most of the loss, and will intersect in a complex, nonlinear manner with climate change. We find that some 30% of the Madagascar’s chameleons may lose in the future nearly all their habitats, critically jeopardizing their chance for survival.

Photographic Checklist, DNA Barcoding, and New Species of Sea Slugs and Snails from the Faafu Atoll, Maldives (Gastropoda: Heterobranchia and Vetigastropoda)

Baseline biodiversity data are key for ecological and evolutionary studies and are especially relevant for areas such as the Maldivian Archipelago in the Indian Ocean, which can act as a stepping-stone for the transport of widely distributed marine species. We surveyed the islands and reefs of the Faafu and Malé Atolls with snorkeling and scuba diving, collecting the two gastropod subclasses, Heterobranchia and Vetigastropoda. Our inventory comprises 104 species photographed alive to create an identification guide. We also provide COI barcodes for most species, adding novel sequence data for the Maldivian malacofauna. Half of our species represent new records for the Maldives, emphasizing how much diversity remains to be discovered. Species distributions reflect ecological rarity, with almost 60% of taxa only found in one site. We also compiled a comprehensive checklist of heterobranchs and vetigastropods of the Maldives based on literature records, resulting in 320 species, which, together with barcoding data, indicate several potential cryptic species in the Indo-Pacific. Six new species are described, the nudibranchs Limenandra evanescenti n. sp., Eubranchus putnami n. sp., Sakuraeolis marhe n. sp., Moridilla maldivensis n. sp., Tergiposacca perspicua n. sp., and the sacoglossan Costasiella fridae n. sp.

Large herbivores facilitate the persistence of rare taxa under tundra warming

Ecological rarity, characterized by low abundance or limited distribution, is typical of most species, yet our understanding of what factors contribute to the persistence of rare species remains limited. Consequently, little is also known about whether rare species might respond differently than common species to direct (e.g., abiotic) and indirect (e.g., biotic) effects of climate change. We investigated the effects of warming and exclusion of large herbivores on 14 tundra taxa, three of which were common and 11 of which were rare, at an inland, low-arctic study site near Kangerlussuaq, Greenland. Across all taxa, pooled commonness was reduced by experimental warming, and more strongly under herbivore exclusion than under herbivory. However, taxon-specific analyses revealed that although warming elicited variable effects on commonness, herbivore exclusion disproportionately reduced the commonness of rare taxa. Over the 15-year duration of the experiment, we also observed trends in commonness and rarity under all treatments through time. Sitewide commonness increased for two common taxa, the deciduous shrubs Betula nana and Salix glauca, and declined in six other taxa, all of which were rare. Rates of increase or decline in commonness (i.e., temporal trends over the duration of the experiment) were strongly related to baseline commonness of taxa early in the experiment under all treatments except warming with grazing. Hence, commonness itself may be a strong predictor of species’ responses to climate change in the arctic tundra biome, but large herbivores may mediate such responses in rare taxa, perhaps facilitating their persistence.

Species richness and biogeographical affinities of the marine molluscs from Bahía de Chamela, Mexico.

For more than 10 years (2007-2018), the benthic macroinvertebrates of Bahía de Chamela (Mexican Pacific) were sampled at 31 sites (0-25 m depth). A total of 308 species of the five main classes of benthic molluscs were obtained (106 bivalves, 185 gastropods, 13 polyplacophorans, two scaphopods and two cephalopods). This is a significant increase in the number of species (246 new records) compared to the 62 species previously recorded more than 10 years ago. The distribution in the 31 localities of the bay is given for the first time for most of the species, together with information on its ecological rarity (incidence in the samples). Two families of bivalves (Veneridae and Mytilidae) and three families of gastropods (Calyptraeidae, Muricidae and Collumbellidae) comprised ~ 30% of all species. Ecological rarity was evident with 45 families (45.0%) with only one species and 178 species (57.8%) collected in one site and 67 (21.8%) in two sites. The molluscs of Bahía de Chamela represent 12.2% of all species recorded in the Mexican Pacific. Their biogeographic affinities are mostly related to the Tropical Eastern Pacific (TEP) including the oceanic islands and a few are restricted to the Tropical Mexican Pacific (TMP). Some have broader distributions to adjacent northern and southern temperate regions of the American Pacific, one to the western Atlantic, two pantropical (PAN) and two cosmopolitans (COS). The range distribution of each species was reviewed and updated, thus finding that seven species have extended their ranges of geographic distribution.

Global distribution and conservation status of ecologically rare mammal and bird species

Identifying species that are both geographically restricted and functionally distinct, i.e. supporting rare traits and functions, is of prime importance given their risk of extinction and their potential contribution to ecosystem functioning. We use global species distributions and functional traits for birds and mammals to identify the ecologically rare species, understand their characteristics, and identify hotspots. We find that ecologically rare species are disproportionately represented in IUCN threatened categories, insufficiently covered by protected areas, and for some of them sensitive to current and future threats. While they are more abundant overall in countries with a low human development index, some countries with high human development index are also hotspots of ecological rarity, suggesting transboundary responsibility for their conservation. Altogether, these results state that more conservation emphasis should be given to ecological rarity given future environmental conditions and the need to sustain multiple ecosystem processes in the long-term.

An ecological perspective on 'plant carnivory beyond bogs': nutritional benefits of prey capture for the Mediterranean carnivorous plant Drosophyllum lusitanicum.

Little is known about the evolutionary and ecological drivers of carnivory in plants, particularly for those terrestrial species that do not occur in typical swamp or bog habitats. The Mediterranean endemic Drosophyllum lusitanicum (Drosophyllaceae) is one of very few terrestrial carnivorous plant species outside of Australia to occur in seasonally dry, fire-prone habitats, and is thus an ecological rarity. Here we assess the nutritional benefits of prey capture for D. lusitanicum under differing levels of soil fertility in situ. We measured the total nitrogen and stable nitrogen and carbon isotope ratios of D. lusitanicum leaves, neighbouring non-carnivorous plant leaves, and groups of insect prey in three populations in southern Spain. We calculated trophic enrichment (ε15N) and estimated the proportion of prey-derived nitrogen (%Nprey) in D. lusitanicum leaves, and related these factors to soil chemistry parameters measured at each site. In all three populations studied, D. lusitanicum plants were significantly isotopically enriched compared with neighbouring non-carnivorous plants. We estimated that D. lusitanicum gain ~36 %Nprey at the Puerto de Gáliz site, ~54 %Nprey at the Sierra Carbonera site and ~75 %Nprey at the Montera del Torero site. Enrichment in N isotope (ε15N) differed considerably among sites; however, it was not found to be significantly related to log10(soil N), log10(soil P) or log10(soil K). Drosophyllum lusitanicum individuals gain a significant nutritional benefit from captured prey in their natural habitat, exhibiting proportions of prey-derived nitrogen that are similar to those recorded for carnivorous plants occurring in more mesic environments. This study adds to the growing body of literature confirming that carnivory is a highly beneficial nutritional strategy not only in mesic habitats but also in seasonally dry environments, and provides insights to inform conservation strategies for D. lusitanicum in situ.

A late-surviving Triassic protomonaxonid sponge from the Paris Biota (Bear Lake County, Idaho, USA)

Protomonaxonid sponges are a major group of Cambrian and Ordovician fossils in exceptionally preserved (especially Burgess Shale-type) faunas, but are rare thereafter. Rare examples of apparent surviving lineages are known from the late Palaeozoic and Mesozoic, but by this time more derived groups of sponges have generally displaced them in at least shallow-water (shelf depth) ecosystems. The early Spathian (Early Triassic) Paris Biota includes abundant material of a new leptomitid protomonaxonid, Pseudoleptomitus advenus Botting nov. gen., nov. sp., distinguished by having an unbundled longitudinal skeleton and very weak transverse component. This is the first post-Ordovician leptomitid known, and indicates long-term survival of the group in unknown environments. Its occurrence near storm wave base is similar to the preferred environment of earlier examples of the family, suggesting either ecological rarity or taphonomic reasons for their ∼200-million-year absence from later Palaeozoic rocks.

Cuban land use and conservation, from rainforests to coral reefs

Cuba is an ecological rarity in Latin America and the Caribbean region. Its complex political and economic history shows limited disturbances, extinctions, pollution, and resource depletion by legal or de facto measures. Vast mangroves, wetlands, and forests play key roles in protecting biodiversity and reducing risks of hazards caused or aggravated by climate change. Cuba boasts coral reefs with some of the region's greatest fish biomass and coral cover. Although it has set aside major protected areas that safeguard a host of endemic species, Cuba's environment is by no means pristine. Through much of its early history, deforestation and intensive agricultural production under colonial then neocolonial powers was the norm. Using remote sensing, we find Cuba's land today is 45% devoted to agricultural, pasturage, and crop production. Roughly 77% of Cuba's potential mangrove zone is presently in mangrove cover, much of it outside legal protection; this is likely the most intact Caribbean mangrove ecosystem and an important resource for coastal protection, fish nurseries, and wildlife habitat. Even the largest watersheds with the most agricultural land uses have a strong presence of forests, mangroves, and wetlands to buffer and filter runoff. This landscape could change with Cuba's gradual reopening to foreign investment and growing popularity among tourists-trends that have devastated natural ecosystems throughout the Caribbean. Cuba is uniquely positioned to avoid and reverse ecosystem collapse if discontinuities between geopolitical and ecosystem functional units are addressed, if protection and conservation of endemic species and ecosystems services accompany new development, and if a sound ecological-restoration plan is enacted.

Seasonal distribution and reproductive strategy of seahorses

AbstractThe unique morphology and life history characteristics make seahorses excellent flagship species for marine ecosystems. The ecological rarity of seahorses has made it difficult to address fundamental demographic processes of seahorses, such as seasonal migration and ecological characteristics. This 3-year investigation evaluated, for the first time, the seasonal distribution of a wild seahorse, Hippocampus mohnikei, and its ecological significance. The results revealed a significant difference in the abundance of wild H. mohnikei populations between warm and cold seasons, indicating that seahorses might undertake a seasonal inshore-offshore migration every year. A total of 42 794 samples were taken during the 3-year survey in the Laizhou Bay, and migratory seahorses had the highest reproductive rates from July to September each year, suggesting that seahorse reproduction might be an important trigger for variation in distribution and migration. Moreover, water temperature might also affect the temporal and spatial abundance of migratory seahorses. There was no genetic subdivision among the different geographical populations of H. mohnikei along China’s coast. In conclusion, this study confirmed that large-scale seasonal seahorse migrations occur periodically and that reproduction is one of the important drivers, suggesting that closed-season fishing of breeding grounds is essential and applicable for seahorse conservation.

Performing weeds: Gardening, plant agencies and urban plant conservation

Private domestic gardens have been the site of diverse inquiry in both the social and natural sciences. Intersected by these inquiries this paper focuses on how ‘weeds’ are (re)constituted through gardening practices in domestic gardens in Christchurch, New Zealand. The paper arises out of an interdisciplinary ecological and social scientific study of the factors influencing the distribution and regeneration of 12 bird-dispersed native woody species from Riccarton Bush, an urban forest remnant of significant ecological rarity, into surrounding residential properties. As part of this study we were especially interested in how people’s everyday experiences and encounters in their gardens guide their gardening practices and what possibilities, if any, these create for self-introduced native seedlings to establish, and mature into adults. Drawing inspiration from literatures on human–plant relations we use the concepts of performance, non-human and ‘planty’ agencies to argue that weeds are performed by people and plants rather than having a pre-determined or pre-figured meaning. Empirically the paper seeks to highlight the diverse, unique and disruptive agencies of plants. Methodologically it reflects on ways of engaging with and researching human–plant relations. In concluding, the paper examines how concepts of performance, non-human and planty agencies can provide insights for weed management and urban plant conservation.

Should we correct rarity measures for body size to evaluate arthropod vulnerability? Insights from Mediterranean tenebrionid beetles

We investigated the influence of body size on rarity patterns at a regional scale using the tenebrionid beetles of Latium (Central Italy). For this we calculated geographical range size (no. of 10 km square cells), habitat breadth (no. of phytoclimatic units), and abundance (no. of sampled individuals) using a large database containing 3,561 georeferenced records for 84 native species. For each species, we used total body length to correct rarity measures for body size. Then we calculated vulnerability (Kattan) indices using both corrected and uncorrected rarity scores. Finally we used species range trends (expanded vs. contracted) as a measure of actual species decline. We found that range trends were correlated with vulnerability index independently from body size correction, the species with the highest vulnerability being those that experienced the strongest range contraction for both corrected and uncorrected measures. Also, we found that correcting for body size may be problematic because of the weak correlations between body size and geographical and ecological rarity (notably, abundance was not correlated). These findings indicate that correcting rarity for body size is not only theoretically questionable, but also practically difficult and possibly useless for conservation purposes.

Fundamentos ecológicos y biogeográficos de la rareza de la avifauna madrileña: Una propuesta de modificación del catálogo regional de especies amenazadas

The conservation status of bird species of Comunidad de Madrid is analysed using the ecological breadth of the species, the distribution area, their habitat preferences, and maximum ecological densities in the region. The species which are less widely distributed in Madrid are characterized by their low maximum ecological densities, narrow habitat breadths, and limited distribution in the Iberian peninsular. Another component defining regional rarity shows that large-sized species tend to reach lower densities than small-sized birds. These two gradients of ecological rarity are closely associated with the current categories of threat status in Madrid, and allow the proposal and justification of possible modifications of the regional catalogue for 11 species.

Significant coastal fish and wildlife habitat protection in New York's coastal management program

Abstract Diversity of animal species inhabiting New York State's coastal area is recognized through the designation of significant habitats based on their importance for vulnerable species, population levels, ecological rarity, and human importance. Protection of these habitats, and species diversity throughout the coast, is available through the implementation of a habitat policy within New York's Coastal Management Program. Approximately 240 habitat areas are in various stages of a designation and approval process throughout the state's coastal area for protection under this policy. The implementation of the habitat policy has been limited, due in part to the difficulty of using an ecological approach for determining possible habitat impairment. Despite difficulties encountered in implementing habitat protection, the Coastal Zone Management Act provides a useful approach for protection of species diversity.