Terrestrial Islands Research Articles

Comparing Historical and Contemporary Observations of Avian Fauna on the Yáláƛi (Goose Island) Archipelago, British Columbia, Canada.

In an era of global change, historical natural history data can improve our understanding of ecological phenomena, particularly when evaluated with contemporary Indigenous and place-based knowledge. The Yáláƛi (Goose Island) Archipelago is a group of islands in Heiltsuk (Haíɫzaqv) territory on the Central Coast of British Columbia, Canada. Not only has this region been important to the Heiltsuk for millennia but also it is both a federally and internationally recognized important bird area. In this study, we compare data collected by Charles J. Guiguet, a biologist who documented bird communities at Yáláƛi in the summer of 1948, to three different contemporary surveys and to citizen-science data. We find that the relative abundances of forest bird species (i.e., birds that use the terrestrial island ecosystems) in 1948 differed to those observed in systematic surveys in 2011. While Orange-crowned Warblers, Dark-eyed Juncos, and Red Crossbills comprised 55% of detections by Guiguet in 1948, the three most abundant species in 2011 were Bald Eagles, Varied Thrushes, and Pacific Wrens, and these accounted for only 25% of detections. Although we could not make a quantitative comparison, we provide summaries of each species observed in surveys or reported on eBird. We also incorporate Heiltsuk place-based knowledge to enrich our discussion of the variability in bird communities over time, from how changes in mammal communities and human use may have shaped vegetation dynamics to how large-scale natural phenomena impacted topography. To understand which birds are present and how their communities are changing over time, we recommend continued monitoring of the bird communities at Yáláƛi.

The ecological and evolutionary dynamics of inselbergs.

Islands are fundamental model systems in ecology, biogeography, and evolutionary biology. However, terrestrial islands, unlike their aquatic counterparts, have received comparatively less attention. Among these land islands, inselbergs (i.e. isolated rock outcrops with diverse lithologies and a modest topographical prominence) stand out as iconic examples distributed worldwide across global biomes. Due to their durable lithology, inselbergs change slowly, persisting for tens of millions of years. In this review, we propose a biological definition for inselbergs that captures three fundamental characteristics of inselbergs from the perspective of biota. These are old age, isolation and the presence of unique microhabitats that are rare or absent in the surrounding matrix, fostering distinct communities often with unique and endemic biota. We synthesise the state of the art and formulate a set of testable hypotheses to deepen our understanding of the origins and maintenance of diversity on inselbergs, which are increasingly exposed to anthropogenic threats. By offering different habitats compared to the surrounding habitat matrix (e.g. moist microhabitats in dryland landscapes and xeric environments in humid tropical landscapes), inselbergs may allow specific lineages to thrive beyond their typical geographical limits. Particularly in drylands and degraded landscapes, inselbergs may not just provide different habitats but also act as ecological refuges or evolutionary refugia by providing a wider range of potential microhabitats than the surrounding matrix, enhancing resilience and promoting regional biodiversity. The central role of the matrix ensures that the ecological and evolutionary dynamics of inselbergs differ from those of true islands such as oceanic islands. Given that inselberg biota coexist within a terrestrial matrix, interactions between inselberg and matrix populations impact each other significantly. Over evolutionary timescales, matrix species may contract to inselberg refugia, preserving lineages while cycles of isolation and reconnection may drive speciation via a species pump. Although inselberg biodiversity has been studied predominantly from an island biogeography perspective, we argue that depending on the spatial scale, habitat specificity and mobility of the organisms considered, a range of different theories and paradigms can help explain the biogeography and local distribution patterns of different taxonomic and functional groups of inselberg species.

The origin and dispersal of Firmiana danxiaensis among isolated specific landscapes

AbstractChina has the most numerous Danxia and Karst landscapes, which serve as special terrestrial islands harboring ample endemic species, though how did these endemic species spread among those isolated sites is still an unresolved issue. To address this question, we explored the phylogeographical structure and demographic history of Firmiana danxiaensis, a tree species endemic to Danxia and Karst landscapes. We collected 295 samples (28 populations) of F. danxiaensis. Plastid genomes were assembled for 25 representative samples. Sanger sequencing of four plastid regions and restriction‐site‐associated DNA sequencing were performed on the 28 populations. The phylogenetic tree constructed from plastid genomes and restriction site‐associated DNA sequencing (RAD‐seq) data supported that F. danxiaensis originated from Mount Danxia and Nanxiong Basin, spread to Karst landscapes near Yingde City, and then back to Danxia Mountain and the Nanxiong Basin. In the Nanxiong Basin, the latter arrivals captured the plastid of the former. Population analyses revealed strong population structure among and within Danxia and Karst landscapes, possibly due to low seed and pollen dispersal abilities of the species. The demographic and ecological niche modeling approaches suggested that F. danxiaensis have widely occurred in the southeast of China during the last glacial period, and later retreated to the cliffs of Danxia and Karst landscapes due to temperature rising and competition failure. The declining of the effective population size of the species throughout the postglacial period suggested that global warming, agriculture, and industrial civilizations could have affected the survival of this species, and more measures should be taken to conserve these species.

The First Nationwide Surveillance of Severe Fever with Thrombocytopenia Syndrome in Ruminants and Wildlife in Taiwan.

Since the first discovery of severe fever with thrombocytopenia syndrome virus (SFTSV) in China in 2009, SFTSV has rapidly spread through other Asian countries, including Japan, Korea, Vietnam and Pakistan, in chronological order. Taiwan reported its first discovery of SFTSV in sheep and humans in 2020. However, the prevalence of SFTSV in domestic and wildlife animals and the geographic distribution of the virus within the island remain unknown. A total of 1324 animal samples, including 803 domestic ruminants, 521 wildlife animals and 47 tick pools, were collected from March 2021 to December 2022 from 12 counties and one terrestrial island. The viral RNA was detected by a one-step real-time reverse transcription polymerase chain reaction (RT-PCR). Overall, 29.9% (240/803) of ruminants showed positive SFTSV RNA. Sheep had the highest viral RNA prevalence of 60% (30/50), followed by beef cattle at 28.4% (44/155), goats at 28.3% (47/166), and dairy cows at 27.5% (119/432). The bovine as a total of dairy cow and beef cattle was 27.8% (163/587). The viral RNA prevalence in ticks (predominantly Rhipicephalus microplus) was similar to those of ruminants at 27.7% (13/47), but wild animals exhibited a much lower prevalence at 1.3% (7/521). Geographically the distribution of positivity was quite even, being 33%, 29.1%, 27.5% and 37.5% for northern, central, southern and eastern Taiwan, respectively. Statistically, the positive rate of beef cattle in the central region (55.6%) and dairy cattle in the eastern region (40.6%) were significantly higher than the other regions; and the prevalence in Autumn (September-November) was significantly higher than in the other seasons (p < 0.001). The nationwide study herein revealed for the first time the wide distribution and high prevalence of SFTSV in both domestic animals and ticks in Taiwan. Considering the high mortality rate in humans, surveillance of other animal species, particularly those in close contact with humans, and instigation of protective measures for farmers, veterinarians, and especially older populations visiting or living near farms or rural areas should be prioritized.

The effect of seabird presence and seasonality on ground-active spider communities across temperate islands.

Seabirds influence island ecosystems through nutrient additions and physical disturbance. These influences can have opposing effects on an island's invertebrate predator populations. Spiders (order: Araneae) are an important predator in many terrestrial island ecosystems, yet little is known about how seabird presence influences spider communities at the intraisland scale, or how they respond to seasonality in seabird colony attendance.We investigated the effects of seabird presence and seasonality on ground-active spider community structure (activity-density, family-level richness, age class, and sex structure) and composition at the family-level across five short-tailed shearwater breeding islands around south-eastern Tasmania, Australia. Using 75 pitfall traps (15 per island), spiders were collected inside, near, and outside seabird colonies on each island, at five different stages of the short-tailed shearwater breeding cycle over a year. Pitfall traps were deployed for a total of 2674 days, capturing 1592 spiders from 26 families with Linyphiidae and Lycosidae the most common. Spider activity-density was generally greater inside than outside seabird colonies, while family-level richness was generally higher outside seabird colonies. For these islands, seabird breeding stage did not affect activity-densities, but there were some seasonal changes in age class and sex structures with more adult males captured during winter. Our results provide some of the first insights into the spatial and temporal influences seabirds have on spider communities. We also provide some of the first records of spider family occurrences for south-eastern Tasmanian islands, which will provide an important baseline for assessing future change.

The Limpopo–Mpumalanga–Eswatini Escarpment—Extra-Ordinary Endemic Plant Richness and Extinction Risk in a Summer Rainfall Montane Region of Southern Africa

Climatic, edaphic, and topographic differences between mountains and surrounding lowlands result in mountains acting as terrestrial islands with high levels of endemic biota. Conservation of mountains is thus key to successful biodiversity conservation. The Limpopo–Mpumalanga–Eswatini Escarpment (LMEE) in South Africa and the Kingdom of Eswatini is one of the largest components of southern Africa’s Great Escarpment. Despite botanical collecting effort over 150 years, there has never been a holistic and comprehensive synthesis of plant endemics data for the LMEE. For the first time, we define the LMEE as an orographic entity, covering 53,594 km2; it forms a contiguous highland area from the Pongola River in the south, north to the Woodbush area, and includes rugged western Eswatini. Using exhaustive literature mining, coupled with combined decades of fieldwork by the authors, and up-to-date taxonomic assessments of the 46 undescribed species, we provide the first robust list of plant endemics for the LMEE. The LMEE has 496 endemic plant taxa, comprising 10.7% of the provisional flora (4,657 taxa). This is more than double the endemic plant taxa in the Drakensberg Mountain Centre (DCM), and may be the richest concentration of montane endemics in southern Africa outside of the Core Greater Cape Floristic Region. Grassland hosts the largest number of endemics (74.2%), followed by Savanna (26.6%), then Forest (7.7%). Most endemics of conservation concern occur in Grassland (68.4%), in which one is Extinct and two are Extinct in the Wild. Evolutionary partitioning between Grassland, Savanna and Forest is suggested by low introgression of Biomes at family and genus level, and by a dominance of life-forms adapted to open habitats. High threat statuses for Grassland endemics can be attributed to the historical transformation of almost 20% of Grassland to forestry pre-1990, and ongoing degradation of primary Grassland. With conservation area coverage only 11.1% of the LMEE, the exceptional richness of the endemic flora—combined with major conservation threats—suggest that the LMEE should become a major focus of conservation effort between South Africa and Eswatini as a matter of urgency.

Multiple mountain‐hopping colonization of sky‐islands on the two sides of Tropical Africa during the Pleistocene: The afroalpine Festuca grasses

AbstractAimThe afroalpine sky‐islands present one of the most interesting models to study discrete biogeographic patterns in a terrestrial island system. Here, we performed range‐wide sampling of the afroalpine clade of fine‐leaved Festuca grasses and address a set of hypotheses on its origin and dispersal. We focus on the widespread species F. abyssinica and explore the role of the eastern and western African sky‐islands.LocationTropical Africa.TaxonAfroalpine Festuca.MethodsWe combine data from field surveys, phylogeography, coalescence‐based dispersal modelling, and environmental niche and dispersal costs analyses to infer patterns of genetic diversity, genealogical relationships, colonization routes and range shifts under two Quaternary climates (current – to represent warm periods; and Last Glacial Maximum (LGM) – to represent cold periods).ResultsThe westernmost populations in East Africa show higher genetic diversity and higher similarities with the West African populations and the Ethiopian Simen Mountains than with the more closely situated East African populations. Dispersal models and ecological niche predictions of F. abyssinica supported multiple long‐distance dispersals (LDD) among the eastern African sky‐islands, and at least two dispersal events between the two sides of Africa (0.86 Ma and 0.52 Ma), probably facilitated by bridging suitable habitats during the coldest periods of the Pleistocene.Main conclusionsWe reconstruct an afroalpine mountain‐hopping dispersal model, with migrations occurring between adjacent sky‐islands in eastern Africa, and through a Central Africa–Sudan pathway connecting afroalpine patches on the two sides of the continent.

A functional trait‐based approach to assess the impact of an alien palm invasion on plant and soil communities on a South Pacific island

AbstractIn island ecosystems, biological invasions are one of the major threats to native biodiversity and to ecosystem functioning. Invasive ornamental plants such as the alien palm tree Pinanga coronata in the Fiji islands can form mono‐dominant stands in rainforests and displace native species. Using a functional trait‐based approach, we investigated the impact of P. coronata on both above and belowground communities (i.e. plants and Collembola). Within a rainforest reserve on Fiji´s principal island, we sampled a total of 10 invaded and non‐invaded plots and recorded five functional traits for plants and six for Collembola. We found that invasion by P. coronata led to a strong and significant decrease of native plants and Collembola taxonomic diversity. Ingress of P. coronata also induced a decrease in the functional diversity of plant communities and to a lesser extent of Collembola communities. P. coronata invasion led to a decrease of leaf carbon–nitrogen ratio (LCN), Leaf nitrogen content (LN), specific leaf area (SLA) and leaf dry matter content (LDMC) of plant communities, suggesting a change in litter properties compared to non‐invaded communities. Plots with P. coronata were associated with large Collembola living at the soil surface with more trichobothria and pseudocelli, which are used as defence mechanisms. Using trait‐matching, we also found that the strength of plant‐soil relationships was higher (i.e. more stable) in non‐invaded plots than in P. coronata‐invaded plots. Lastly this study suggests that the main mechanism through which P. coronata alters soil communities is a change in plant properties rather than a change in the abiotic environment. Our trait‐based approach underlines the negative impact of this alien palm invasion on native rainforest plant and soil fauna in Fiji, and the urgent need for on‐the‐ground action to conserve terrestrial island biodiversity in Fiji´s rainforests.

Marine lakes as biogeographical islands: a physical model for ecological dynamics in an insular marine lake, Palau

Marine lakes are emerging ecological and evolutionary natural experimental systems, with genetically isolated resident populations that exhibit extreme population dynamics and rapid phenotypic change. Marine lakes are posited to be marine islands, however, unlike terrestrial islands for which rich models have been developed over the past half-century, we know little of the mechanisms driving changes in marine lakes. This is a critical knowledge gap in efforts to reconcile theory on, or distinguish differences among, island and island-like systems. To reduce this critical knowledge gap, we present a mathematical model describing marine lakes based on a case study of Jellyfish Lake (Ongeim’l Tketau, Mecherchar: OTM), Palau. Empirical data show that marine lakes exhibit delayed and reduced tidal motions, suggesting exchange of a limited amount of water with the neighboring (‘mainland’) ocean. Our model tracks changes in lake level, allowing determination of an exchange rate that is a physical null model for biological colonization and a proxy for colonization distance in island biogeography theory. In addition, we track horizontally averaged in-lake quantities such as salinity and temperature (i.e., marine weather, climate) and stratification (i.e., habitat) — that are known to influence resident species’ distributions and population dynamics — by solving an advection-diffusion equation. We find that weather, ocean conditions, groundwater, and exchanges through tunnels determine the abiotic environment in OTM. By comparing simulations and data, we estimate the difficult-to-measure properties of the surrounding groundwater — the ‘matrix’ in the vernacular of habitat islands — and give a range of realistic values for the effective diffusion coefficient. This coefficient is found to increase in a tropical storm, suggesting that other drivers can be important during perturbations.

Long-Term Changes in Terrestrial Vegetation Linked to Shifts in a Colonial Seabird Population

Seabirds that form large colonies often act as biovectors that transport and concentrate large amounts of nutrients, metals, and contaminants from marine feeding areas to inland breeding grounds. This enrichment can potentially transform and structure primary productivity, vegetation communities, and species richness. In a previous paleolimnological study, we examined approximately 1700 years of population change in the world’s largest colony of Leach’s Storm-petrel (Hydrobates leucorhous) on Baccalieu Island (Newfoundland and Labrador, Canada) and, using a variety of proxies, we identified two peaks in colony around 500 and 1980 CE. Here, we analyzed the same sediment cores for fossil pollen assemblages to explore the effects of changing seabird populations on terrestrial vegetation. Aerial imagery revealed the island’s vegetation cover that increased from about 23% to about 58% between 1940 and 2017, in part coinciding with the rapid colony growth until around 1980. Palynological analyses indicated shifts from tree and shrub habitat to storm-petrels’ preferred habitat of fern, grass, and moss during peak seabird abundances around 500 and 1980 CE. Also, during peaks in colony size, nitrogen-fixing alder (Alnus spp.) decreased in relative abundance likely due to poorer competitive potential because of guano-derived nitrogen fertilization. Furthermore, we observed increases in fungal hyphae concurrent with the inferred size of the storm-petrel colony, providing the potential for a novel proxy to track burrowing seabirds in sediment records. Collectively, our data show that storm-petrels acted as ecosystem engineers by markedly modifying the island’s vegetation cover and composition. If global seabird colonies continue to decline at current rates, there may be considerable bottom-up ramifications to terrestrial island ecosystems.

Strong genetic structure in Dyckia excelsa (Bromeliaceae), an endangered species found on ironstone outcrops in Pantanal, Brazil

AbstractThe plant communities associated with iron-rich outcrops are still little known about to their genetic structure and diversity. Outcrops are often considered to be ‘terrestrial islands’, and gene flow among populations on different outcrops is presumed to be hampered by the isolation effect provided by the surrounding matrix. Here, we studied the genetic diversity and structure of populations of Dyckia excelsa to test the hypothesis that the disjunction of the ironstone outcrops where this species occurs promotes its highly structured genetic variability. Seven nuclear microsatellite markers and two plastid DNA intergenic spacers (rps16-trnK and rpl32-trnL) were used to characterize individuals from seven locations in the region of Urucum Residual Plateau, Mato Grosso do Sul State, Brazil. These markers low haplotype and allelic diversity and high levels of genetic divergence among outcrops, indicating prolonged genetic isolation, with diversification of haplotypes dating from the Pleistocene (1.0 Mya). Pollen movement may occur between neighbouring populations, resulting in a pattern of isolation-by-distance. For conservation purposes, it is recommended that D. excelsa be preserved in situ in each specific location given the low levels of gene flow and the high degree of genetic uniqueness in each group of populations investigated.

Development of anchialine cave habitats and karst subterranean estuaries since the last ice age

Extinction models generally predict that coastal and neritic fauna benefit during sea-level rise (transgression), whereas sea-level retreat (regression) diminishes their suitable habitat area and promotes evolutionary bottlenecks. Sea-level change also impacts terrestrial island biogeography, but it remains a challenge to evidence how sea-level rise impacts aquatic island biogeography, especially in the subterranean realm. Karst subterranean estuaries (KSEs) occur globally on carbonate islands and platforms, and they are populated by globally-dispersed, ancient ecosystems (termed anchialine). Anchialine fauna currently exhibit a disjunct biogeography that cannot be completely explained by plate tectonic-imposed vicariance. Here we provide evidence that anchialine ecosystems can experience evolutionary bottlenecks caused by habitat reduction during transgression events. Marine-adapted anchialine fauna benefit from habitat expansion during transgressions, but fresh- and brackish-adapted fauna must emigrate, evolve to accommodate local habitat changes, or are regionally eliminated. Phanerozoic transgressions relative to long-term changes in subsidence and relief of regional lithology must be considered for explaining biogeography, evolution, local extirpation or complete extinction of anchialine fauna. Despite the omission of this entire category of environments and animals in climate change risk assessments, the results indicate that anchialine fauna on low-lying islands and platforms that depend upon meteoric groundwater are vulnerable to habitat changes caused by 21st century sea-level rise.

Beyond isolation by distance: What best explains functional connectivity among populations of three sympatric plant species in an ancient terrestrial island system?

AbstractAimUnderstanding how landscape features affect gene flow is critical to connectivity conservation and restoration management. Here, we examined the relationship between functional connectivity (gene flow) and structural connectivity (area and spatial configuration of habitats) in three co‐occurring short‐range plant taxa in an ancient terrestrial island system.LocationLow‐altitude mountain range south‐western Australia.MethodsWe analysed spatial patterns of genetic differentiation at nuclear microsatellite loci using Bayesian clustering. Circuit theory modelling was used to generate all possible pathways that connect populations as resistance distance matrices based on two surfaces for each taxon. The first surface assumes a flat terrain and tests whether genetic similarity declines only with distance—isolation by distance (IBD). The second surface is habitat suitability based on species distribution modelling (SDM), which tests whether genetic similarity is a function of connected and suitable habitat. Multiple matrix regression with randomization was used to test the significance of the resistance distance matrices at predicting two metrics of genetic differentiation (FST and DEST). Variance explained was partitioned using redundancy analysis.ResultsGenetic structure for the insect‐pollinated taxa—Acacia adinophylla—and Tetratheca aphylla subsp. aphylla was at similar spatial scales. Unexpectedly, a higher level of genetic structure was found in the wind‐pollinated Lepidosperma bungalbin. IBD best explained the gene flow of A. adinophylla (R2 = 0.41–0.43) with partial support provided by habitat suitability (R2 = 0.04–0.07). In contrast, connectivity by habitat suitability was highest for T. aphylla subsp. aphylla (R2 = 0.56–0.59). Drivers of L. bungalbin connectivity were inconsistent between the two measures of genetic differentiation.Main conclusionsGene flow is facilitated by different factors for the three taxa. Habitat fragmentation would most strongly impede gene flow for T. aphylla subsp. aphylla. Geographical distance cannot be assumed as the sole or best determinant of gene flow among populations, nor can findings be generalized to coexisting taxa.

Geese are overlooked dispersal vectors for vascular plants in archipelago environments

AbstractQuestionWe addressed the importance of gut‐mediated dispersal by greylag geese for vascular plants in archipelago environments and asked: (a) What proportion of the local species pool is dispersed by geese? (b) Which plant traits characterize species dispersed by geese? (c) Which plant communities are likely to benefit from endozoochory by geese?LocationThree Swedish Baltic archipelagos.MethodsGoose droppings were collected on 45 islands. Plants germinating from the droppings represent the endozoochorous species pool (ESP). On 108 islands, the presence of vascular plants was recorded in each habitat. These species represent the island species pool (ISP). Differences in functional traits between ESP and ISP were expressed as effect sizes and tested using meta‐regressions. Using indicator species analyses and indicator species for managed semi‐natural grasslands, we identified the primary habitats of the ESP.ResultsGeese dispersed viable diaspores of 97 plant species, which represents 22% of the ISP. Most ESP species were typical for small islands. Geese dispersed a higher proportion of graminoids and less woody plants, higher proportions of chamaephytes and therophytes and less phanerophytes; annuals and bi‐annuals were significantly overrepresented. On average, seed volume of the ESP was 95% smaller than that of the ISP. About 51% of all ESP species were dispersed in at least two archipelagos. Geese showed a bias towards species of rocky shore habitats.ConclusionGeese potentially disperse large amounts of diaspores of many terrestrial island plant species. Through their feeding behaviour, geese select species with certain suites of traits from the regional species pool. Plant dispersal by geese may benefit plants species of rocky shores, but species of formerly managed semi‐natural grasslands may also find refuge sites on epilittoral shores after goose‐mediated dispersal. The relative importance of geese as dispersal vectors may increase under on‐going land‐use changes and cessation of grazing networks.

First evidence of faunal succession in terrestrial vertebrates of the Plio-Pleistocene of the Balearic Islands, western Mediterranean

Terrestrial vertebrates from the karst filling in Cap d’Artrutx, situated in the extreme Southwest of Menorca (Balearic Islands, western Mediterranean) have yielded interesting information on the migration and extinction dynamics in the terrestrial island vertebrate faunas in Mallorca and Menorca between the late Pliocene and early Pleistocene. In this site, remains of the Menorcan giant tortoise (“Testudo” gymnesica Bate, 1914) and two mammals (Nesiotites sp. and Hypnomys sp.) have been found. The remains of the Menorcan giant tortoise represent the youngest record of this species and of the so-called second faunistic group of the island. The morphology and size of Nesiotites sp. are comparable to those of Nesiotites aff. ponsi Reumer, 1979 from the Plio-Pleistocene of Pedrera de S’Ònix (Mallorca) and Nesiotites meloussae Pons and Moyà, 1980 (=Nesiotites aff. ponsi sensu Pons-Monjo et al., 2012) from the lower Pleistocene of Binigaus (Menorca). Hypnomys sp. can belong to an archaic species not yet described. They represent the first evidence of the entrance of the third faunistic group, which originally evolved on the neighbouring island of Mallorca. This association is interpreted, therefore, as the first evidence of a faunal succession in the Plio-Pleistocene in the Balearic Islands.

Persistence and stochasticity are key determinants of genetic diversity in plants associated with banded iron formation inselbergs.

The high species endemism characteristic of many of the world's terrestrial island systems provides a model for studying evolutionary patterns and processes, yet there has been no synthesis of studies to provide a systematic evaluation of terrestrial island systems in this context. The banded iron formations (BIFs) of south-western Australia are ancient terrestrial island formations occurring within a mosaic of alluvial clay soils, sandplains and occasional granite outcropping, across an old, gently undulating, highly weathered, plateau. Notably, these BIFs display exceptionally high beta plant diversity. Here, we address the determinants and consequences of genetic diversity for BIF-associated plant species through a comprehensive review of all studies on species distribution modelling, phylogenetics, phylogeography, population genetics, life-history traits and ecology. The taxa studied are predominantly narrowly endemic to individual or a few BIF ranges, but some have more regional distributions occurring both on and off BIFs. We compared genetic data for these BIF-endemic species to other localised species globally to assess whether the unique history and ancestry of BIF landscapes has driven distinct genetic responses in plants restricted to this habitat. We also assessed the influence of life-history parameters on patterns of genetic diversity. We found that BIF-endemic species display similar patterns of genetic diversity and structure to other species with localised distributions. Despite often highly restricted distributions, large effective population size or clonal reproduction appears to provide these BIF-endemic species with ecological and evolutionary resilience to environmental stochasticity. We conclude that persistence and stochasticity are key determinants of genetic diversity and its spatial structure within BIF-associated plant species, and that these are key evolutionary processes that should be considered in understanding the biogeography of inselbergs worldwide.

Floristic and ecological characterization of habitat types on an inselberg in Minas Gerais, southeastern Brazil

ABSTRACT Inselbergs are granitic or gneissic rock outcrops, distributed mainly in tropical and subtropical regions. They are considered terrestrial islands because of their strong spatial and ecological isolation, thus harboring a set of distinct plant communities that differ from the surrounding matrix. In Brazil, inselbergs scattered in the Atlantic Forest contain unusually high levels of plant species richness and endemism. This study aimed to inventory species of vascular plants and to describe the main habitat types found on an inselberg located in the state of Minas Gerais, in southeastern Brazil. A total of 89 species of vascular plants were recorded (belonging to 37 families), of which six were new to science. The richest family was Bromeliaceae (10 spp.), followed by Cyperaceae (seven spp.), Orchidaceae and Poaceae (six spp. each). Life forms were distributed in different proportions between habitats, which suggested distinct microenvironments on the inselberg. In general, habitats under similar environmental stress shared common species and life-form proportions. We argue that floristic inventories are still necessary for the development of conservation strategies and management of the unique vegetation on inselbergs in Brazil.

Inducible defenses in Olympia oysters in response to an invasive predator.

The prey naiveté hypothesis suggests that native prey may be vulnerable to introduced predators because they have not evolved appropriate defenses. However, recent evidence suggests that native prey sometimes exhibit induced defenses to introduced predators, as a result of rapid evolution or other processes. We examined whether Olympia oysters (Ostrea lurida) display inducible defenses in the presence of an invasive predator, the Atlantic oyster drill (Urosalpinx cinerea), and whether these responses vary among oyster populations from estuaries with and without this predator. We spawned oysters from six populations distributed among three estuaries in northern California, USA, and raised their offspring through two generations under common conditions to minimize effects of environmental history. We exposed second-generation oysters to cue treatments: drills eating oysters, drills eating barnacles, or control seawater. Oysters from all populations grew smaller shells when exposed to drill cues, and grew thicker and harder shells when those drills were eating oysters. Oysters exposed to drills eating other oysters were subsequently preyed upon at a slower rate. Although all oyster populations exhibited inducible defenses, oysters from the estuary with the greatest exposure to drills grew the smallest shells suggesting that oyster populations have evolved adaptive differences in the strength of their responses to predators. Our findings add to a growing body of literature that suggests that marine prey may be less likely to exhibit naiveté in the face of invasive predators than prey in communities that are more isolated from native predators, such as many freshwater and terrestrial island ecosystems.

Islands in a Sea of Mud: Insights From Terrestrial Island Theory for Community Assembly on Insular Marine Substrata.

Most marine hard-bottom habitats are isolated, separated from other similar habitats by sand or mud flats, and can be considered analogous to terrestrial islands. The extensive scientific literature on terrestrial islands provides a theoretical framework for the analysis of isolated marine habitats. More individuals and higher species richness occur on larger marine substrata, a pattern that resembles terrestrial islands. However, while larger terrestrial islands have greater habitat diversity and productivity, the higher species richness on larger marine hard substrata can be explained by simple surface area and hydrodynamic phenomena: larger substrata extend further into the benthic boundary, exposing fauna to faster current and higher food supply. Marine island-like communities are also influenced by their distance to similar habitats, but investigations into the reproductive biology and dispersal ability of individual species are required for a more complete understanding of population connectivity. On terrestrial islands, nonrandom co-occurrence patterns have been attributed to interspecific competition, but while nonrandom co-occurrence patterns have been found for marine fauna, different mechanisms are responsible, including epibiontism. Major knowledge gaps for community assembly in isolated marine habitats include the degree of connectivity between isolated habitats, mechanisms of succession, and the extent of competition on hard substrata, particularly in the deep sea. Anthropogenic hard substrata of known age can be used opportunistically as "natural" laboratories to begin answering these questions.

Rocky islands in a sea of mud: biotic and abiotic factors structuring deep-sea dropstone communities

Stones released by melting icebergs are called dropstones, and these stones constitute island-like hard-bottom habitats at high latitudes. In 2012, dropstone megafauna in the HAUSGARTEN observatory in the Fram Strait was sampled photographically. We tested the hypothesis that dropstones would have the same species distribution patterns as terrestrial islands, using 5 patterns commonly found in the classical island literature. Higher richness, diversity, and abundance of fauna occurred on larger stones and on stones near a deep-water rocky reef. These patterns can be explained by the greater surface area of larger stones, the exposure of larger stones to faster current higher in the benthic boundary layer, and increased larval supply from the rocky reef. Some pairs of morphotypes (12 pairs out of 56 morphotypes and 1540 possible pairs) co-occurred less often than expected by chance. While similar patterns have been attributed to interspecific competition in the classical island literature, we offer alternative mechanisms for dropstones. Non-random co-occurrence on dropstones may be explained by larval dispersal. Dropstone fauna had an overdispersed (clumped) distribution, so pairs of morphotypes may have negative non-random co-occurrence simply because short larval life and limited dispersal ability prevent them from having randomly overlapping distributions. In addition, we found 8 morphotype pairs that co-occurred more often than expected by chance because of epibiontism. The patterns found in dropstone communities resemble terrestrial islands, but different mechanisms may be responsible.