No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
An equilibrium theory of insular zoogeography
... and the latter affects immigration rates (He & Legendre, 1996;MacArthur & Wilson, 1963, 1967. Species turnover is a key aspect of the theory, the equilibrium on an island resulting from the continuing variation in the gain and loss of species. ...
... As in ETIB (MacArthur & Wilson, 1963, 1967, species richness at equilibrium B eq (species) is reached when E t crosses I t (Figure 3). The number of years after the eruption when B eq is reached, T eq (year), can be easily assessed graphically or by examination of the matrices ( Figure 3). ...
... Therefore, our NTIB provides evidence that the number of ecological niches available on an island explains why island area often correlates with species richness (Lomolino et al., 2006;MacArthur & Wilson, 1963, 1967. However, the correlation between the number of niches and area was diminished when all latitudes were considered together because tropical islands (as a given oceanic or terrestrial area) have more niches and therefore more species than temperate or polar islands (or areas) of the same size (Beaugrand, 2023;Beaugrand et al., 2020). ...
The equilibrium theory of island biogeography (ETIB) is a widely applied dynamic theory proposed in the 1960s to explain why islands have coherent differences in species richness. The development of the ETIB was temporarily challenged in the 1970s by the alternative static theory of ecological impoverishment (TEI). The TEI suggests that the number of species on an island is determined by its number of habitats or niches but, with no clear evidence relating species richness to the number of niches however, the TEI has been almost dismissed as a theory in favour of the original ETIB. Here, we show that the number of climatic niches on islands is an important predictor of the species richness of plants, herpetofauna and land birds. We therefore propose a model called the niche‐based theory of island biogeography (NTIB), based on the MacroEcological Theory on the Arrangement of Life (METAL), which successfully integrates the number of niches sensu Hutchinson into ETIB. To account for greater species turnover at the beginning of colonisation, we include higher initial extinction rates. When we test our NTIB for resident land birds in the Krakatau Islands, it reveals a good correspondence with observed species richness, immigration and extinction rates. Provided the environmental regime remains unchanged, we estimate that the current species richness at equilibrium is ~45 species (range between 38.39 and 61.51). Our NTIB provides better prediction because it counts for changes in species richness with latitude, which is not considered in any theory of island biogeography.
... The original theory of island biogeography (MacArthur and Wilson 1963Wilson , 1967) focused on island area and isolation in a static context and only briefly touched upon the subject of in situ speciation and adaptive radiation. However, MacArthur and Wilson (1963Wilson ( , 1967 were visionary in proposing the existence of a "radiation zone," that is, islands that are sufficiently isolated and large to be able to host species radiations. ...
... The original theory of island biogeography (MacArthur and Wilson 1963Wilson , 1967) focused on island area and isolation in a static context and only briefly touched upon the subject of in situ speciation and adaptive radiation. However, MacArthur and Wilson (1963Wilson ( , 1967 were visionary in proposing the existence of a "radiation zone," that is, islands that are sufficiently isolated and large to be able to host species radiations. Several decades later, their idea was proved to be correct following studies using molecular phylogenies (Rosindell and Phillimore 2011;Valente et al. 2020), which confirmed that cladogenetic speciation in birds is more common on large, isolated islands, such as the Galápagos and Hawaii. ...
... The Nesospiza finches also constitute one of the few cases of adaptive radiation in birds (Supplemental Table S1). A key proposal of MacArthur and Wilson's theory of island biogeography is that islands should tend toward a dynamic equilibrium in which the number of species remains constant even though the identity of the species can vary (turnover) (MacArthur and Wilson 1963Wilson , 1967. Therefore, whether avian radiations on islands tend toward a diversity equilibrium has been a subject of particular interest. ...
Understanding the mechanisms underlying species formation and differentiation is a central goal of evolutionary biology and a formidable challenge. This understanding can provide valuable insights into the origins of the astonishing diversity of organisms living on our planet. Avian evolutionary radiations on islands have long fascinated biologists as they provide the ideal variation to study the ecological and evolutionary forces operating on the continuum between incipient lineages to complete speciation. In this review, we summarize the key insights gained from decades of research on adaptive and nonadaptive radiations of both extant and extinct insular bird species. We present a new comprehensive global list of potential avian radiations on oceanic islands, based on published island species checklists, taxonomic studies, and phylogenetic analyses. We demonstrate that our understanding of evolutionary processes is being greatly enhanced through the use of genomic tools. However, to advance the field, it is critical to complement this information with a solid understanding of the ecological and behavioral traits of both extinct and extant avian island species.
... The present study analyses the structure of wintering bird assemblages occurring in a large number of small water bodies located in the metropolitan area of Rome, to assess the patterns of the occurrence, abundance and richness of species. It is hypothesized that: (i) the number of wintering species increases with increasing size, following the species-area relationship applied to mainland fragment archipelagos (MacArthur & Wilson 1963;Diamond 1975;Connor & McCoy 2001; see review in Watling &Donnelly 2006 andMagurran &McGill 2011);(ii) there are size thresholds of these water bodies wherein mean species richness and abundance significantly increase; and (iii) consistent with the relationship between the distribution and abundance applied to wet ecosystems (Paracuellos & Teller ıa 2004;Paracuellos 2006), the most widely diffused species (i.e. higher frequency of occurrence) also are the more abundant. To this end, the results of this study may be useful for pond management and planning in large urbanized landscapes. ...
... A species-area relationship was finally obtained, based on the equation (MacArthur & Wilson 1963): ...
... The value of the z coefficient for the species/area relationship (i.e. the angular coefficient of the regression line between species and area) represents important information reflecting the degree of isolation of an archipelago for a specific target (MacArthur & Wilson 1963;Abbott 1983). ...
This study reports on the patterns of species occurrence, abundance and richness of a wintering water-related bird assemblage in an 'archipelago' of 70 small artificial urban ponds (AUPs) embedded in a metropolitan landscape (Rome, central Italy). A total of 20 species in 26 AUPs were sampled. Only the largest AUPs (>0.1 ha) contained all these species , except for Gallinula chloropus. The highest total mean species abundance was observed in the largest ponds, with statistically significant differences evident among size classes. Two significant spatial thresholds in species abundance and richness were observed (between 0.01 and 0.1 ha; between 0.1 and 1 ha in size). The abundance of single species was correlated with their frequency of occurrence. Ponds in urban areas must be larger than 0.1 ha to host a rich winter assemblage of birds, with a further increase in richness noted with a surface area larger than 1 ha. The highest number of species was observed in the larger ponds (>1 ha). The species richness of each AUP is directly correlated to their size (log-transformed species-area relationship: log S = 3.515 + 0.497 log A; R 2 = 0.76). Further research should be conducted to confirm these patterns and to implement information useful for planning and management of artificial ponds in urban areas for this purpose.
... Through the lens of island biogeographic [11] and ecosystem decay theory [12], the decreasing area of calcareous grasslands should be accompanied by a loss of within-patch biodiversity and habitat quality, including floral and nesting resources. The positive effect of habitat area [13,14] and flower resources on pollinators has been shown frequently [15,16]. ...
... Calcareous grassland area was the strongest predictor of pollinator species richness and thus is in accordance with the species-area relationship predicted by island biogeographic theory [11]. Large calcareous grasslands promote solitary bees and butterflies [64,65] and endangered species even more since these species are often specialized on one habitat [64,66]. ...
Pollinator diversity is declining due to habitat loss, low habitat quality, limited habitat connectivity and intensification of agriculture in remaining high-value habitats within human-dominated landscapes, such as calcareous grasslands. Options to increase the local area of protected habitats are often limited. Therefore, we asked how local habitat quality as well as agri-environmental schemes (AES) and configuration of the surrounding landscape can contribute to the preservation of pollinator diversity. We sampled bees, butterflies and hoverflies in 40 calcareous grasslands in Germany, and assessed the effects of calcareous grassland area, quality and connectivity, agricultural configuration, and AES on species richness and abundance. While calcareous grassland area was an important predictor for bee and butterfly species richness, with strongest effects sizes for endangered species, local flower resources and nesting sites and landscape characteristics such as small field size, high proportion of organic fields and connectivity with other grasslands significantly enhanced pollinator richness with responses differing among the three studied taxa. In contrast to expectations, AES flowering fields did not benefit pollinator communities in grasslands. We conclude that improving local habitat quality in combination with targeted landscape management are effective measures to promote pollinator richness in highly fragmented protected grassland.
... Although the islands occupy less than 7% of the land, they are inhabited by one-fifth of all modern species of terrestrial animals and plants (Fernández-Palacios et al., 2021). Evolutionary changes on the islands occur much faster than on the mainland due to ecosystem simplification, isolation, small sizes, and high population density (MacArthur and Wilson, 1963). Owing to the unique evolutionary history of each island and geographic isolation, the oceanic islands are considered as natural laboratories of biodiversity and museums of disappearing evolutionary lineages (Gibson et al., 2017;Whittaker et al., 2017). ...
... Owing to the unique evolutionary history of each island and geographic isolation, the oceanic islands are considered as natural laboratories of biodiversity and museums of disappearing evolutionary lineages (Gibson et al., 2017;Whittaker et al., 2017). It is especially convenient to conduct eco-evolutionary studies on the islands (MacArthur and Wilson, 1963). ...
... Although the islands occupy less than 7% of the land, they are inhabited by one-fifth of all modern species of terrestrial animals and plants (Fernández-Palacios et al., 2021). Evolutionary changes on the islands occur much faster than on the mainland due to ecosystem simplification, isolation, small sizes, and high population density (MacArthur and Wilson, 1963). Owing to the unique evolutionary history of each island and geographic isolation, the oceanic islands are considered as natural laboratories of biodiversity and museums of disappearing evolutionary lineages (Gibson et al., 2017;Whittaker et al., 2017). ...
... Owing to the unique evolutionary history of each island and geographic isolation, the oceanic islands are considered as natural laboratories of biodiversity and museums of disappearing evolutionary lineages (Gibson et al., 2017;Whittaker et al., 2017). It is especially convenient to conduct eco-evolutionary studies on the islands (MacArthur and Wilson, 1963). ...
Reptiles, birds, and mammals inhabiting oceanic islands tend to change many ecological, behavioral, and genetic characteristics. These changes are referred to as the “island syndrome”. The behavioral components of these changes have been little studied so far. Based on a 40-year study of the biology of the Arctic fox (Vulpes lagopus) on the Mednyi Island, we show that the island Arctic foxes changed many behavioral characteristics compared to mainland foxes. They use smaller home ranges, travel shorter daily distances, and their dispersal distance from the natal territory is much smaller. An increase in the family size of the island Arctic foxes, together with a decrease in litter size, leads to an increase in parental and kin investment and increased cooperation between family members. At the same time, the island foxes, to a large extent, lost their fear of humans. These features are consistent with those found in other island populations. On the other hand, in contrast to other island populations, Mednyi Arctic foxes have increased territoriality, apparently in response to an increased risk of infanticide. Furthermore, Mednyi Arctic foxes expose sex-biased dispersal and maternal inheritance of home range, which are absent in the mainland foxes. The sex-biased dispersal can be considered a mechanism for avoiding inbreeding. Comparison with island fox (Urocyon littoralis) populations in the Channel Islands (Southern California) suggests that these traits have evolved under the influence of specific environmental drivers of the Mednyi Island: patchy and highly predictable resource distribution. The particular resource distribution led to the increased importance of another driver, social landscape, and a new behavioral metatrait of the Mednyi fox – increased conservatism in spatial, reproductive, and foraging behavior.
... Island area is often cited as a key driver of the number of species that can coexist locally (MacArthur and Wilson 1963, Karger et al. 2014, Ibanez et al. 2018, Schrader et al. 2019a. Larger islands support a larger species pool for local communities, which therefore have more potential species (Ricklefs 1987). ...
... This could reflect increasing distance from the wet tropical source pool of mainland Southeast Asia, as opposed to Australia where Neogene aridification drove widespread extinction of rainforest taxa (Byrne et al. 2011, Kooyman et al. 2019. Heightened diversity with closer proximity to the western source pool suggests that dispersal distances have been crucial for the formation of modern diversity in Indonesia (MacArthur and Wilson 1963). Greater chance of tropical lineage dispersal, from the western source pool, also promotes their opportunities for diversification (Crayn et al. 2015, Morley 2018b, Atkins et al. 2019, Kooyman et al. 2019). ...
Tropical forests occupy small coral atolls to the vast Amazon basin. They occur across bioregions with different geological and climatic history. Differences in area and bioregional history shape species immigration, extinction and diversification. How this effects local diversity is unclear. The Indonesian archipelago hosts thousands of tree species whose coexistence should depend upon these factors. Using a novel dataset of 215 Indonesian forest plots, across fifteen islands ranging in area from 120 to 785 000 km², we apply Gaussian mixed effects models to examine the simultaneous effects of environment, earthquake proximity, island area and bioregion upon tree diversity for trees ≥ 10 cm diameter at breast height. We find that tree diversity declines with precipitation seasonality and increases with island area. Accounting for the effects of environment and island area we show that the westernmost bioregion Sunda has greater local diversity than Wallacea, which in turn has greater local diversity than easternmost Sahul. However, when the model includes geological activity (here proximity to major earthquakes), bioregion differences are reduced. Overall, results indicate that multi‐scale, current and historic effects dictate tree diversity. These multi‐scale drivers should not be ignored when studying biodiversity gradients and their impacts upon ecosystem function.
... Six times throughout the cruise, 2 l samples from the water column were collected from Niskin bottles deployed on a rosette sampler and pressure filtered using a peristaltic pump onto inline 25 mm, 5.0 μm pore-size polyester (Sterlitech), and 0.2 μm poresize polyethersulfone (Pall Supor) filters housed in Swinnex filter holders, at depth of 95,145,195,330, and 500 m depths. Separately, at an additional six times during the cruise, 1 l samples were pumped using positive pressure onto 0.2 μm Sterivex filter cartridges from 5,20,35,50,65,80,95,120,145,195,330, and 500 m depths. The microbial communities, representing the "freeliving" community, from these samples are previously reported [32]. ...
... Particle size is of particular importance because it may inf luence particle colonization rates and the availability of ecological niches [78,79]. This is analogous to findings from terrestrial ecology, where plant and animal species richness has been shown to increase with island size [80]. Bacterial community richness has been shown to increase as a power law relationship with habitat size [78,79,[81][82][83][84] and particle size classes from 0.2 to 200 μm throughout marine water columns [72,85]. ...
Microbial community dynamics on sinking particles control the amount of carbon that reaches the deep ocean and the length of time that carbon is stored, with potentially profound impacts on Earth’s climate. A mechanistic understanding of the controls on sinking particle distributions has been hindered by limited depth- and time-resolved sampling and methods that cannot distinguish individual particles. Here, we analyze microbial communities on nearly 400 individual sinking particles in conjunction with more conventional composite particle samples to determine how particle colonization and community assembly might control carbon sequestration in the deep ocean. We observed community succession with corresponding changes in microbial metabolic potential on the larger sinking particles transporting a significant fraction of carbon to the deep sea. Microbial community richness decreased as particles aged and sank; however, richness increased with particle size and the attenuation of carbon export. This suggests that the theory of island biogeography applies to sinking marine particles. Changes in POC flux attenuation with time and microbial community composition with depth were reproduced in a mechanistic ecosystem model that reflected a range of POC labilities and microbial growth rates. Our results highlight microbial community dynamics and processes on individual sinking particles, the isolation of which is necessary to improve mechanistic models of ocean carbon uptake.
... On shorter time scales, over thousands of years, islands have often been considered as static land masses with biogeographic processes mainly driven by immigration and extinction based on present-day island configurations as hypothesized by the Equilibrium Theory of Island Biogeography (ETIB; MacArthur and Wilson 1963). However, during these shorter time scales, volcanic islands, when volcanically active, represent one of the most dynamic environments on the planet with high rates and magnitudes of surface area and archipelagic configuration changes, here denoted as geo-spatial changes. ...
... Superimposed on this purely volcanic dynamism, it has long been realized that Pleistocene sea level changes simultaneously affect islands and configurations of archipelagos and species distributions (e.g., Diamond 1972;Diamond and Gilpin 1983). The Glacial Sensitive Model (GSM; Fernández-Palacios et al. 2016) indicates that island surface areas and connectivity are not static as assumed by the ETIB (MacArthur and Wilson 1963), but instead fluctuate dynamically in response to Pleistocene climatic cycles. Moreover, recent studies suggest that the legacy of past changes are still detectable in present-day species richness patterns on islands and may have influenced evolutionary processes (Warren et al. 2015, Borregaard et al. 2017, Simaiakis et al. 2017, Whittaker et al. 2017, Ávila et al. 2018a, b, 2019. ...
We modelled the geospatial dynamics of both volcanic activity and sea level change on a volcanic island (Terceira, Azores) to map out how combined area change dynamics over 120 kyr could affect biogeographical and evolutionary processes.
... The species-area relationship [10,11] and island biogeographic theory [4,12] suggest that larger islands host greater species richness, often due to increased habitat complexity and population sizes. Island biogeographic theory also postulates that distance between regions, a proxy for connectivity, correlates with species richness. ...
Islands have long represented natural laboratories for studying many aspects of ecology and evolutionary biology, from speciation to community assembly. One aspect that has been well documented is the correlation between island size and taxonomic diversity, likely due to decreased complexity and population size on small islands. This same logic can apply to genetic diversity, which should predictably decrease with effective population size. The island size–diversity correlation has received support over the years but often focuses on single metrics of genetic diversity. Here, we use Zosterops white-eyes in the Solomon Islands to study the correlation between island size and various metrics related to genetic diversity, including runs of homozygosity and fixation of transposable elements. We find that almost all these metrics strongly correlate with island size, and in turn with each other. We infer that island size is independently correlated with these different variables, demonstrating that population size impacts genomic metrics of diversity in a variety of ways across temporal and hierarchical scales.
... They are geographically limited by the ocean and were never connected to continental landmasses as they originated via volcanism, and were never in contact with the continents. These attributes confer them important advantages for the study of biogeography (MacArthur & Wilson, 1963) and also help to expand our knowledge in fields as diverse as community ecology, macroevolution and population genetics (Overcast et al., 2023;Warren et al., 2015). ...
Multiple‐island endemics (MIE) are considered ideal natural subjects to study patterns of island colonization that involve recent population‐level genetic processes. Kleinia neriifolia is a Canarian MIE widespread across the archipelago, which exhibits a close phylogenetic relationship with species in northwest Africa and at the other side of the Sahara Desert. Here, we used target sequencing with plastid skimming (Hyb‐Seq), a dense population‐level sampling of K. neriifolia , and representatives of its African–southern Arabian relatives to infer phylogenetic relationships and divergence times at the species and population levels. Using population genetic techniques and machine learning (convolutional neural networks [CNNs]), we reconstructed phylogeographic relationships and patterns of genetic admixture based on a multilocus SNP nuclear dataset. Phylogenomic analysis based on the nuclear dataset identifies the northwestern African Kleinia anteuphorbium as the sister species of K. neriifolia , with divergence starting in the early Pliocene. Divergence from its sister clade, comprising species from the Horn of Africa and southern Arabia, is dated to the arid Messinian period, lending support to the climatic vicariance origin of the Rand Flora. Phylogeographic model testing with CNNs supports an initial colonization of the central island of Tenerife followed by eastward and westward migration across the archipelago, which resulted in the observed east/west phylogeographic split. Subsequent population extinctions linked to aridification events, and recolonization from Tenerife, are proposed to explain the patterns of genetic admixture in the eastern Canary Islands. We demonstrate that CNNs based on SNPs can be used to discriminate among complex scenarios of island migration and colonization.
... The theory of island biogeography (MacArthur & Wilson 1963;MacArthur & Wilson 1967) was originally developed to understand the effect of island environment, including isolation, to species richness and species speciation. It was developed to understand the biodiversity occurring in ent sense rather than only real island, such as succulent vegetation in arid environment in Africa (Desmet & Cowling 2004) and completely submerge marine habitat (Neigel 2003). ...
In anthropogenic islands as urban parks, the fern species richness and composition may be determined ecologically by the quality of habitat, including area greenness, or biogeographically by area size. As the development of the theory of island biogeography also includes man-made parks, it is feasible to test whether area-species relationship applies in these urban parks, and is more pronouncedly evident compared to another ecological factor, such as NDVI. Total species number and composition of 8 urban parks in a kecamatan in Tegal Regency were collected and arranged in clustering methods to understand the similarity between parks. The similarity analysis result is important for the management of the parks in Slawi. The species richness data is subsequently tested using Pearson correlation and regression against NDVI and area sizes. The relation between NDVI and species richness is non-significant (p=0.058), while area size and species richness is significant (p=0.003). This signifies that the urban fern species richness is determined by area as biogeographical factor, compared to NDVI as ecological factor. This result is important for the purpose of designing and managing urban parks as evidently size is important in the effort of attracting native biodiversity into urban parks and in turn enhancing the well-being of urban population.
... To identify hotspots and coldspots of species introduction, we used a General Linear Mixed Model (GLMM 61 in which we used the number of first records as dependent variable and as explanatory variables we used country area size and a proxy of country's recording effort. The first variable was used to account for species-area relationships, wherein regions with larger areas tend to harbor more species 62 . The proxy variable for recording effort encompassed both proactive measures (e.g., surveillance initiatives) and reactive responses (e.g., national action plans for invasive species management) as defined by Early et al. 63 . ...
Mosquitoes are regarded as the most dangerous creatures on earth, spreading deadly pathogens through their bites. Human activities are driving range expansions of many mosquito species by unintentionally introducing them beyond their native ranges. Despite the often dire consequences for human health, a global picture of the introduction trends and the resulting range expansions of mosquitoes is missing. Here, we describe the global invasion patterns of mosquitoes that are vectors of human diseases and analyze the drivers shaping them. In addition, we provide the dataset compiled for these analyses which represent the most up-to-date standardized information on first records for this taxonomic group at a regional level. Our findings reveal that a total of 45 mosquito species have hitherto been introduced into regions outside their native range worldwide, representing 24% of those known to transmit human pathogens in the wild (i.e., outside experimental conditions), with 27 species successfully established. There has been a steep increase in introductions of emerging non-native mosquito species since the mid-20 th century when 28 species (62% of all introduced species). CC-BY 4.0 International license available under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprint this version posted August 7, 2024. ; https://doi.org/10.1101/2024.08.06.606755 doi: bioRxiv preprint 2 were recorded for the first time. In just the last two decades, 12 new species have been identified. The geography of introductions largely mirrors global trade and transportation flows. Initially, most introduced species were native to Africa, but over time, Asian species have become more dominant. North America, Australia and Europe have consistently been the primary recipients. Our results provide a foundation for addressing the increasing threat of non-native vector mosquitoes globally, emphasizing the need for international cooperation and comprehensive control measures to mitigate their impact on public health.
... The use of IBT on protected areas started with the SLOSS (Single large or several small) debate derived from the Equilibrium Model of Island Biogeography (EMIB; (MacArthur and Wilson, 1963)) and based on its assumptions and predictions (Diamond and May, 1981;Higgs, 1981;Triantis and Bhagwat, 2011); although the approach received ample criticism, especially given the absence of sufficient validation (Simberloff and Abele, 1982;Simberloff and Abele, 1976), further refinement and data available started an ongoing debate that remains to date (Fahrig et al., 2022;Liu et al., 2022;Whitaker and Fernández-Palacios, 2007;Wu and Vankat, 1995). The application and further development of the basic EMIB analogy to habitat islands conducted to the general assumptions that favored larger and circular reserves and short inter-reserve distances (Diamond and May, 1981;Hamilton, 2002;Triantis and Bhagwat, 2011), that supported a theoretical debate around the validity and interpretation of the EMIB in the PA context (Whitaker and Fernández-Palacios, 2007). ...
Island Biogeography Theory (IBT) is a foundational framework in conservation science, yet its application to large-scale protected area (PA) design remains relatively understudied. This research investigates the influence of IBT-derived variables on terrestrial vertebrate richness and threatened species abundance within 4990 PAs across continental America. By examining the effects of area, shape, isolation, elevation, latitude, and human influence, we assessed the relative importance of these factors in shaping vertebrate diversity patterns. Our findings reveal that while IBT principles, such as the positive relationship between area and species richness, are evident, the influence of human activities is pervasive. Specifically, latitude and elevation significantly influenced species richness for most taxonomic groups, while area positively affected amphibians, birds, reptiles, and threatened mammals and reptiles. Shape and isolation exhibited varying degrees of impact across different taxa. Critically, human influence emerged as a dominant factor, particularly for birds, including threatened species. These results underscore the complex interplay between natural and anthropogenic processes in shaping biodiversity patterns. To effectively conserve terrestrial vertebrates, and overall biodiversity, PA managers and policy-makers must integrate IBT principles with strategies that address the impacts of human activities, such as habitat loss, fragmentation, and climate change.
... However, there has been no research on animal diversity in the intertidal zone of Xia-Sanheng Island, and almost no case study has investigated the biological diversity of Zhoushan Islands by combining molecular biology classification methods. The diversity of island species is limited by the size of the island, the length of the coastline, and the types of rocks in the intertidal zone (Macarthur and Wilson 1963;Zhu et al. 2010). Xia-Sanheng Island covers less than 1 square kilometer. ...
Intertidal animals are an essential part of the ecosystem, and species diversity can reflect the state of the local ecological environment. However, traditional morphological identification is prone to corresponding classification errors or research limitations. With the development of molecular biology, many techniques and bioinformatics classification methods have been applied to identify species efficiently in recent years. This research aimed to examine the feasibility of DNA barcoding within the identification of intertidal animal species collected from the Xia-Sanheng Island. A total of 41 cox1 gene sequences were obtained by experimentalization or downloaded from the National Center for Biotechnology Information (NCBI) database. Then morphological classification, molecular identification, phylogenetic tree analysis, and Automatic Barcode Gap Discovery (ABGD) method were used to analyze the animal samples. We found that although the molecular classification of molluscs was not accurate enough, the collected specimens could be divided into 15 species, 12 families, and 4 phyla. Tetraclita japonica, Thais luteostoma, and Mytilus coruscus were the dominant species on the Xia-Sanheng Island. Additionally, there may be a new species, Platynereis sp., which needs further confirmation. We suggest that further identification of marine biodiversity should be carried out by combining morphological and molecular biological methods.
... These 2018; Sebastián-González and Green 2013). This trend is consistent with the theoretical relationship between area size and taxonomic richness (MacArthur and Wilson 1963). Given that a larger size involves a larger quantity and diversity of niches and resources, a greater diversity of species could potentially exploit them (Weisberg et al. 2014;Karadimou et al. 2016;Oliveira et al. 2020). ...
We characterize the taxonomic and functional diversity of waterbird communities in mangrove forests of 23 coastal lagoons in the southern Mexican Pacific coast, to evaluate the hypothesis of decline of taxonomic and functional richness of waterbird communities in the face of loss of natural habitat cover and increased fragmentation. We quantified patterns of land use cover, considering the heterogeneity of natural and anthropized vegetation cover as a proxy for human-caused fragmentation, and used generalized linear models to explore the relationship between these two covers with the taxo- nomic richness and functional richness of bird communities. Results show that both aspects of biodiversity positively relate to larger natural habitat areas, while higher fragmentation values have a negative effect on them. Our results sug- gest that habitat loss and fragmentation of vegetation cover negatively affect the diversity of waterbird communities and can compromise their link to ecosystem functioning processes in coastal lagoons, by decreasing their functional diversity.
... The species-area relationship is a well-known determinant of the species richness in a given area (Robert et al. 1963). Therefore, we assumed that the number of threatened species in a given PA is also a function of the total richness. ...
Ensuring the effectiveness of protected areas (PAs) has become a top-priority conservation action. Without management plans to define clear conservation goals and actions, PAs risk failing to protect biodiversity. Yet, management plans are insufficiently detailed or absent for several PAs worldwide. Although biodiversity knowledge is a cornerstone to guide the creation of PAs, we still lack information on its impact on long-term management. Thus, to better understand how biodiversity inventories might bias the management of protected areas, we investigate how these plans relate to the number of threatened species in PAs. Thus, we mapped 10,407 records corresponding to 1,395 threatened flora species in 863 PAs of the Brazilian Atlantic Forest under different jurisdictions and found that PAs with management plans hold twice the number of threatened flora species than those without such plans. Additionally, we found no support for the idea that larger PAs or those under higher anthropic pressure are more likely to have management plans, suggesting that management plans represent a proxy for the attention that PAs receive that goes far beyond necessity. We suggest two major reasons for this result. First, better-studied PAs are more likely to receive public funds to establish their management plans. Second, PAs with management plans and well-defined conservation goals may attract more studies. Both reasons may act synergistically, and we provide guidance on how managers and scientists should overcome these biases.
... Understanding how local faunas form and transition is one of the major topics in biogeography. In the study of community formation, island-like habitats with distinct boundaries, such as islands, lakes and mountain tops, have long been a focus of attention (Brooks, 1950;Losos & Ricklefs, 2009;MacArthur & Wilson, 1963, 1967Rahbek et al., 2019). Island biogeographical theory has attempted to explain species composition in an 'island' using the dynamics of colonization from the species pool 'continent' and speciation and extinction within the island (Whittaker et al., 2008(Whittaker et al., , 2017. ...
Inle Lake is an ancient lake in Myanmar, which is an important area with unique and diverse fauna. Its ichthyofauna is believed to have formed non-radiatively, but the historical processes are poorly understood. To elucidate the mechanisms that shape species diversity in this moderately isolated biogeographical ‘island’, this study focused on a typical endemic fish of Inle Lake, Channa harcourtbutleri (Channidae, Anabantiformes), with its widely distributed sister species, C. limbata, and estimated the historical distribution and diversification processes of the endemic fish based on genome-wide polymorphism (MIG-seq) and mitochondrial DNA data. Channa harcourtbutleri contained two genetically and morphologically distinct groups inhabiting Inle Lake and the surrounding rivers respectively. These two groups were genetically the closest to each other; however, the riverine group showed some similarity to the closely related species, C. limbata from Southeast Asia. The mtDNA haplotypes of the endemic species were not monophyletic; most of the riverine group had haplotypes identical or close to those of C. limbata from the upper Irrawaddy and Salween rivers. The time tree suggested that C. harcourtbutleri diverged from C. limbata in the early Pleistocene and then experienced secondary contact with C. limbata in the late Pleistocene. Genetic and morphological differentiation within C. harcourtbutleri suggests that local adaptation to different environments has played an important role for the coexistence of its two forms with some reproductive isolation. Further, the results highlight the importance of multiple colonization and allopatric speciation in shaping biodiversity in the long-term, moderately isolated environments.
Understanding ecological and evolutionary mechanisms that drive biodiversity patterns is important for comprehending biodiversity. Despite being critically important to the functioning of ecosystems, the mechanisms driving belowground biodiversity are little understood. We investigated the radiation and trait diversity of soil oribatid mites from two mountain ranges, that is, the Alps in Austria and Changbai Mountain in China, at similar latitude in the temperate zone differing in formation processes (orogenesis) and exposed to different climates. We collected and sequenced soil oribatid mites from forests at 950–1700 m at each mountain and embedded them into the chronogram of species from temperate Eurasia. We investigated the phylogenetic age of oribatid mites and compared the node age of species with the mountain uplift time of the Alps and Changbai Mountain. We then inspected trophic variation, geographical range size, and reproductive mode, and identified traits that promote oribatid mite survival and evolution in montane forest ecosystems. We found that oribatid mites on Changbai Mountain are phylogenetically older than species in the Alps. All species on Changbai Mountain evolved long before the uplift of Changbai Mountain, but some species in the Alps evolved after the orogenesis of the Alps. On Changbai Mountain, more species possess broader trophic variation, have larger geographical range sizes, and more often reproduce via parthenogenesis compared to species from the Alps. Species on Changbai Mountain survived the mountain uplift or colonized the mountain thereafter, supporting the view that generalistic traits promote survival and evolution in phylogenetically old soil animal species. Collectively, our findings highlight that combining species traits and phylogeny allow deeper insight into the evolutionary forces shaping soil biodiversity in montane ecosystems.
Les colonies d’oiseaux marins nicheurs impactent la physico-chimie des sols ainsi que les communautés végétales sur les îles. Ces écosystèmes insulaires sont caractérisés par des plantes endémiques adaptées aux conditions stressantes (xéricité, salinité, sol superficiel, vent). Plusieurs études ont permis d’évaluer les effets de l’augmentation démographique d’oiseaux marins, mais peu ont réalisé un suivi sur le long terme en prenant en compte leur déclin après explosion démographique. L’objectif de la présente étude (sur 24 ans) a consisté à mesurer les changements physico-chimiques des sols, de la composition des communautés végétales en relation avec la diminution démographique des Goélands leucophées (Larus michahellis Naumann, 1840) sur les archipels insulaires du Frioul et de Riou (Marseille, France). Les enjeux conservatoires de ce contexte insulaire ont été analysés en caractérisant les types fonctionnels des plantes (formes de croissance de Raunkiaer et stratégies de vie de Grime) et en étudiant la variation des plantes à enjeu de conservation, puisque l’apport de nutriments et de polluants, tels que les éléments traces métalliques, via les goélands peut entraîner leur disparition. Pour cela, des analyses de sol (en 1997 et 2021) ainsi que des relevés floristiques (en 1997, 2008 et 2021) ont été réalisés sur 78 placettes permanentes situées sur neuf îles et sur le littoral continental du Parc national des Calanques. Depuis 1997, les teneurs en nitrogène et le pH ont augmenté, alors que le carbone organique ainsi que le rapport C/N ont diminué. En 2021, les mesures des concentrations en éléments traces révèlent des niveaux de contamination relativement faibles sur le continent et les archipels. De 2008 à 2021, les communautés végétales des îles ont été caractérisées par une augmentation du nombre de plantes rudérales. Le déclin des effectifs de Goélands leucophées n’a pas engendré de diminution des plantes tolérantes aux perturbations ni d’augmentation très significative de la flore à enjeu de conservation, mais a entraîné une augmentation des chamaephytes et du recouvrement total de la strate herbacée. Nos résultats suggèrent donc une rémanence des altérations des paramètres des sols ainsi que des communautés végétales toujours rudéralisées. Cependant, une résilience s’opère en termes de recouvrement de la strate herbacée lorsque la pression des goélands diminue.
Island ecosystems have emerged as vital model systems for evolutionary and speciation studies due to their unique environmental conditions and biodiversity. This study investigates the population divergence, hybridization dynamics, and evolutionary history of hybridizing golden‐backed and red‐backed Dinopium flameback woodpeckers on the island of Sri Lanka, providing insights into speciation processes within an island biogeographic context. Utilizing genomic analysis based on next‐generation sequencing, we revealed that the Dinopium hybrid zone on this island is a complex three‐way hybrid zone involving three genetically distinct populations: two cryptic populations of golden‐backed D. benghalense in the north and one island‐endemic red‐backed population of D. psarodes in the south of Sri Lanka. Our findings indicate asymmetric introgressive hybridization, where alleles from the southern D. psarodes introgress into the northern D. benghalense genome while phenotype remains adapted to their respective northern arid and southern wet habitats. The discovery of two genetically distinct but phenotypically similar D. benghalense populations in northern Sri Lanka highlights the process of cryptic population differentiation within island ecosystems. These populations trace their ancestry back to a common ancestor, similar to the Indian form D. b. tehminae, which colonized Sri Lanka from mainland India during the late Pleistocene. Subsequent divergence within the island, driven by selection, isolation by distance, and genetic drift, led to the current three populations. Our findings provide evidence of cryptic diversification and within‐island population divergence, highlighting the complexity of hybridization and speciation processes. These findings further emphasize the intricate nature of evolutionary dynamics in island ecosystems.
Ecosystem size and spatial resource flows are key factors driving species diversity and ecosystem function. However, the question of whether and how these drivers interact has been largely overlooked. Here, we investigated how ecosystem size asymmetry affects species diversity and function of two‐patch meta‐ecosystems connected through flows of nonliving resources. We conducted a microcosm experiment, mimicking resource flows between ecosystems of different sizes yet otherwise identical properties or between ecosystems of the same size. Meta‐ecosystems with asymmetric ecosystem sizes displayed higher α‐diversity but lower β‐diversity and ecosystem function (total biomass) than their unconnected counterparts. At the same time, such an effect was not found for meta‐ecosystems of identical patch sizes. Our work demonstrates how the size of ecosystems, interconnected via resource flows, can modulate cross‐ecosystem dynamics, having implications for species diversity and function across scales.
Aim
We assess the systematic relationships and historical biogeographic patterns in the subfamily Scincinae, a group of lizards that primarily inhabits the Afro‐Madagascan and Saharo‐Arabian regions with isolated lineages in Europe, North America, East Asia, India and Sri Lanka. The contemporary distribution of these lineages on the historical Laurasian and Gondwanan landmasses make scincines an ideal system to study the roles of vicariance and dispersal on a geologic scale of tens of millions of years.
Location
Global.
Taxon
Subfamily Scincinae (Family Scincidae).
Methods
We conducted biogeographic analyses on a reconstructed, time‐calibrated species tree of scincine genera, including members of the other Scincidae subfamilies, using seven nuclear loci (~6 k base pairs). We also constructed a lineage‐through‐time plot to assess the timing of diversification within scincines.
Results
Our analysis estimated strong support for the monophyly of Scincinae that is further comprised a strongly‐supported Gondwanan clade nested within a broader Laurasian group. While most of the extant, genus‐level diversity within the Gondwanan clade was accrued post‐Eocene, the majority of the Laurasian lineages diverged during the Palaeocene or earlier, suggesting large‐scale extinctions on continents of Laurasian origin. Counterintuitively, scincines from India and Sri Lanka have distinct biogeographical origins despite a long tectonic association between these landmasses, suggesting at least two independent, long‐distance, trans‐oceanic dispersal events into the subcontinent. Our biogeographic analyses suggest that scincines likely originated in East and Southeast Asia during the late Cretaceous ( ca . 70 Ma), and eventually dispersed westwards to Africa and Madagascar, where their greatest current‐day species richness occurs.
Main Conclusions
Our study demonstrates the concomitant roles of dispersal and extinction in shaping modern‐day assemblages of ancient clades such as scincine lizards. Our range evolution analysis shows that despite the greater diversity observed in the Afro‐Madagascan region, the origin of scincines can be traced back to Southeast Asia and East Asia, followed by westward dispersals. These dispersals may have been followed by significant extinctions in tropical East Asia, resulting in relatively lower diversity of scincines in these regions. Notably, our analysis reveals that Sri Lankan and Peninsular Indian scincines have distinct evolutionary origins.
Island biogeography theory provides key insights into biodiversity patterns across islands species–area relationships and conservation. However, classical island biogeography theory assumes that species are ecologically equivalent in terms of their dispersal ability. We evaluated the role of a key trait (hand‐wing index, a proxy for dispersal ability in birds) in shaping species‐area relationships of avifauna spanning 6706 species on 3894 islands. High community‐weighted mean (CWM) dispersal ability in regional species pools had widespread but context‐dependent effects on island species‐area relationships. Among island archipelagos at smaller spatial extents, high CWM dispersal ability was associated with steeper species‐area relationships. Among zoogeographical realms at larger spatial extents high CWM dispersal ability was associated with shallower species‐area relationships and higher local species richness on small islands. Our study reveals that geographic variation in species' dispersal traits has strong effects on island species‐area relationships and likely plays an important role in non‐neutral community assembly.
Aim
The study of the theory of island biogeographic (TIB) has focused mainly on plants and vertebrates, with support for the predictions that species richness decreases with distance from the mainland and increases with island size. However, less work has been done on invertebrates. Similarly, the study of the island rule has been studied mainly in vertebrates. A group of invertebrates that can facilitate the study of TIB and the island rule are orchid bees (Apidae: Euglossini), because they are easily collected and show powerful flight performances that allows them to travel long distances. We wondered if these bees would follow the predictions of island biogeography, given that their populations may not be isolated across islands. To test if there is an homogenitazion of orchid bee communities across islands, we evaluated orchid bees abundance and species composition across islands. Besides, we tested the island rule by examining body size variations in individuals collected across islands.
Location
Coiba National Park (Panama).
Time Period
May and June 2023.
Taxa
Orchid bees (Hymenoptera: Apidae: Euglossini).
Methods
By using traps with chemical attractants, we sampled male bees from five islands and the mainland in Coiba National Park in the Pacific side of Panama. We tested the TIB by evaluating whether richness decreased with distance from the mainland or whether increased with island area. To investigate the island rule, and whether there is variation in body size across islands, we used Euglossa imperialis and Euglossa mixta as models, the two most abundant species in the study area.
Results
For the overall orchid bee community, we found that our results fit one of the predictions of IBT, increases in orchid bee abundance with island area; however, species richness did not decrease with isolation and did not increase with island area as predicted by TIB. An interesting result was that as distance from the mainland increased few species became more dominant. Regarding the island rule, we found in the two Euglossa species a marked pattern of reduction in body size as distance from the mainland increased, which seems to outweigh the effect of island size, since the largest island and one of the farthest showed some of the smallest body sizes.
Main Conclusions
Whether euglossine bees travel long distances across islands in marine environments remain unclear. As distance from the mainland increases, few species become dominant, which may be caused by a decrease of resources that favours generalist species. This increase in abundance may explain the decrease in body size with isolation, as perhaps competition for resources increases. Our study provides novel insights to better appraise the dynamics of orchid bees' communities in insular habitats.
Community ecology beginners often struggle to understand theories expressed in complex mathematical formulas and to master computer programming. To remedy this situation, this article provides a practical, R‐based introduction to community ecology by illustrating core concepts (vital rates, carrying capacity, density dependence) and models that can be used to explore the patterns of species abundance and diversity. The structure of this article consists of three modeling exercises, each asking a general question that can be answered by a combination of theory and R programming: (1) what determines the abundance of species, and what makes a population persist and go extinct?; (2) what determines the distribution of species and species diversity?; (3) what determines the relative abundance of species and what allows species to coexist? Through the exercises, I discuss the following five concepts and ideas that provide valuable insights into the questions: (i) the tragedy of the commons, (ii) the theory of island biogeography, (iii) competitive exclusion, (iv) the neutral theory of biodiversity, and (v) frequency dependence. These materials are thus designed to guide the reader in developing an intuition for ecological thinking that will help capture the essence of the global environmental and biodiversity crisis. Although this article does not delineate the scope and depth of the vast field of community ecology, I hope that it will motivate the reader to step up to a more formal introduction to community ecology.
Evolutionary radiations on oceanic archipelagos (ROAs) have long served as models for understanding evolutionary and ecological processes underlying species diversification. Yet, diversity patterns emerging from ROAs have received relatively little attention from biogeographers, even though characterizing the effect of key geo-environmental factors on island clades species distribution could be important for unraveling diversification dynamics. In this study, we conducted a comparative analysis using island-specific species richness values for approximately one hundred ROAs across major oceanic archipelagos (mostly Hawaii, Canary Islands, Galapagos and Fiji) and taxa (vascular plants, invertebrates and vertebrates). Our aim was to determine whether (1) ROA species richness patterns scale as a function of key geo-environmental factors including island area, geological age, environmental heterogeneity (elevation and topographic complexity) and inter-island isolation, and (2) whether the magnitude of the effects of these factors varies across archipelagos and taxa. Our results identified elevation as a key driver of ROA species richness patterns on islands, supporting existing theoretical and empirical work that highlighted the central role of environmental heterogeneity in driving diversification on oceanic islands. As importantly, we found that the influence of geo-environmental factors varies across archipelagos and taxa, suggesting that unique archipelagic dynamics and biological traits together shape diversification differently. Our findings emphasize the value of applying biogeographical modeling at resolution of individual radiations to improve our understanding of evolutionary processes on oceanic archipelagos.
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), insel-bergs 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.
Soil unsealing, the process of removing the impermeable top layer of soil, is increasingly advocated by urban planning policies. The role of unsealed areas in biodiversity conservation, particularly soil biodiversity, remains strongly understudied and especially in understanding the recolonization dynamics of soil biodiversity in these new habitats. Besides, the various types of soil cover resulting from soil unsealing could potentially influence the recolonization kinetics. This study focused on 79 unsealed plots located in 14 schoolyards along the French Mediterranean coast, investigating ant communities through the placement of 485 baits on unsealed plots. Two variables were considered: the duration since soil unsealing (1 or 2 years) and the type of soil cover (wood chips, plantations mulched with wood chips or lawns). Remarkably, these unsealed areas act as habitats for ants from their very first years of creation: a rich number of ant species (21 species; a fifth of the regional pool and 10% of the metropolitan French species) has been observed. Additionally, notable changes in ant communities were evident within a single year: plots unsealed for 2 years exhibited significantly higher indices of ant abundance and species richness compared to those unsealed for 1 year. However, the construction of these spaces influences the present communities, with wood chip-covered areas significantly less rich and abundant in ants compared to other ground cover types. These findings represent a promising starting point and offer insights into the potential of such projects for soil biodiversity conservation.
Islands have played a prominent role in evolutionary and ecological theory, centring the theoretical framework for understanding biodiversity in terms of isolation and area and providing ‘laboratories’ of evolutionary change and adaptive radiation. However, a similar role for islands in understanding global language diversity has not been established, even though one-sixth of the world’s languages are spoken on islands which account for <1% of the inhabited land area. The striking diversity of island languages remains largely unexplained. We construct a global database which reveals that 10% of the world’s languages are endemic to islands (landmasses <11,000 km²) and we test several key theories of language evolution and diversity. We show that language diversity on islands increases with area but does not show a steady decrease with isolation, nor are island languages at elevated risk of loss. However, number of endemic languages per island increases with both area and isolation. We demonstrate that islands shape language evolution, with fewer phonemes (distinct sounds) in island endemic languages with increasing isolation. Our results suggest that islands generate language diversity by accelerating both language change and diversification.
A Hipótese da Quantidade de Habitat (Habitat Amount Hypothesis) é um tema recente na ecologia de paisagens, e pressupõe que a quantidade de habitat em uma paisagem local é o principal determinante da riqueza de espécies. A análise das publicações científicas sobre esse tema pode orientar futuros trabalhos. O objetivo desse trabalho foi fazer uso dessa ferramenta de análise bibliométrica para compreender a evolução bibliométrica do tema Hipotese da Quantidade de Habitat. Este estudo utilizou a análise bibliométrica, uma metodologia quantitativa, para identificar o volume e o padrão de crescimento da literatura nesta área emergente. Os dados bibliométricos foram obtidos nas bases de dados Scopus e Web of Science, utilizando as expressões: “Habitat amount (hypothesis habitat amount) and Landscape ecology (habitat fragmentation) or Biodiversity of fragmented areas”. Foram encontrados 90 artigos sobre o tema entre 2002 e 2022. Lenore Fahrig destaca-se como a pesquisadora mais influente sobre a Hipótese da Quantidade de Habitat. Embora as pesquisas tenham aumentado ao longo do tempo, o tema ainda é tratado de forma incipiente, considerando a importância do estudo da ecologia de paisagens.
Understanding the processes and mechanisms that shape the distribution patterns and variations of biodiversity along spatial gradients continues to be a priority for ecological research. We focused on the biodiversity of benthic diatom communities within a large near‐natural watershed. The objectives are: (1) to explore the overall spatial patterns of benthic diatom biodiversity; (2) to investigate the effects associated with watercourse position and environmental variables, as well as both common and rare species on two facets (i.e., taxonomic and functional) of alpha and beta diversity; and (3) to unveil the mechanisms underlying their spatial variations. Alpha diversity indices along the stream watercourse showed a clear increasing trend from upstream to downstream sites. Results of random forest regression identified conductivity as the primary factor influencing functional alpha diversity, while elevation emerged as the predominant factor for taxonomic alpha diversity. Beta diversity partitioning revealed that taxonomic beta diversity generally exceeded functional beta diversity. These diversity measures exhibited different patterns along the watercourse position: taxonomic beta diversity remained relatively consistent along the watercourse, whereas functional total beta diversity and its two components of middle stream sites were lower than those of upstream and downstream sites. Functional beta diversity was sustained by dominant and common species, while rare species made significant contributions to taxonomic beta diversity. Both taxonomic and functional beta diversity and its components displayed a stronger influence from spatial factors than from local environmental, geo‐climatic, and nutrient variables. Collectively, taxonomic and functional alpha and beta diversity demonstrated distinct responses to the main environmental gradients and spatial factors within our catchment, highlighting their different insights into diatom diversity. Furthermore, research is required to assess the generalizability of our findings to similar ecosystems. In addition, this study presents opportunities for expansion to include other taxa (e.g., macroinvertebrates and fish) to gain a comprehensive understanding of the driving mechanisms behind stream biodiversity.
1. Counts of species in ecological samples are of interest when they tell us about community assembly processes. Older process-based models of count distributions are either complex, widely rejected, or not able to predict high unevenness. 2. I leverage a general strategy for deriving simple one-parameter models. A distribution of abundances x on a continuous scale is predicted from a transform of a uniform distribution U; U is solved for to yield one minus a cumulative distribution function (CDF) for x; and the result is differenced and rounded to down to yield a probability mass function. The same workflow has long been used to derive the geometric series from the exponential distribution. Three variants are proposed, respectively based on the transforms /U – = ( – U)/U where is a constant (a scaled odds ratio); (1/U – 1)1/p where p is a constant; and [–ln(U)/]2 where –ln U is just an exponential random variate and is a constant. 3. The distributions are all consistent with simple population dynamical models in which recruitment rates, and sometimes death rates, vary randomly amongst species and are fixed for each species. The number of recruited offspring produced during each interval by each species is Poisson-distributed, and death rates are per-capita. Population counts are equilibrial, allowing co-existence in the absence of competition. 4. Large-scale surveys of corals, fishes, butterflies, and trees are consistent with the distributions, as are local-scale inventories of trees and assorted vertebrate and insect groups. Each inventory is used to predict the counts of another one that is matched based on group representation, biogeography, and richness. Based on examining decisive differences between the resulting likelihoods, the new models routinely outperform eight different rivals. 5. Thanks to their simplicity, grounding in non-competitive equilibrial population dynamics, and predictive power, the new approaches have considerable relevance throughout ecology.
Small islands tend to lack predators because species at higher trophic levels often cannot survive. However, two exceptional top predators—the Iriomote cat Prionailurus bengalensis iriomotensis, and the Crested Serpent Eagle Spilornis cheela perplexus—live on the small Iriomote Island in the Ryukyu Archipelago. To understand how these predators coexist with limited resources, we focused on their seasonal diets between which conflicts are considered to occur. To compare the diets, we used DNA metabarcoding analysis of faecal samples. In the summer, we identified 16 unique prey items from Iriomote cat faecal samples and 15 unique prey items from Crested Serpent Eagle faecal samples. In the winter, we identified 37 and 14, respectively. Using a non-metric multidimensional scaling and a permutational multivariate analysis of variance, our study reveals significant differences in the diet composition at the order level between the predators during both seasons. Furthermore, although some prey items at the species-to-order level overlapped between them, the frequency of occurrence of most prey items differed in both seasons. These results suggest that this difference in diets is one of the reasons why the Iriomote cat and the Crested Serpent Eagle are able to coexist on such a small island.
Patchy landscapes are characterized by abrupt transitions between habitats, forcing species to cross habitat boundaries in order to spread. Although individuals that disperse into unsuitable habitat are often presumed dead in population models, reality may be more nuanced. If survival within an unsuitable habitat is possible (however transiently), then through time, individuals may be able to reach distant, suitable habitat. In this study, conducted with annual plant species in a fragmented Californian grassland, we examined the fate of habitat specialists moving between serpentine patches and an invaded nonserpentine matrix. First, we tested whether habitat specialists use seed dormancy to transiently survive beyond the habitat boundary. We found that dormancy maintained populations of patch specialists deep into the matrix—these patterns were not observed for matrix specialists in serpentine patches. Seeds of patch specialists that lacked morphologies for assisted dispersal accumulated downslope of patches, suggesting that even the most dispersal‐limited species could eventually reach suitable patches even if they first land in the matrix. Second, because an invasive matrix specialist ( Avena fatua ) is highly abundant, we were interested in determining whether seeds spilled into serpentine patches were strong enough to maintain sink populations. We found that A. fatua was largely absent deep in patches, where the components of fitness plummeted and there was no evidence of a dormant seedbank (in contrast to a sizable seedbank of patch specialists in the matrix). Our results suggest that the demographic fates of individuals that land in unsuitable habitat depend on the direction by which the boundary is crossed (patch ➝ matrix ≠ matrix ➝ patch), with different ecological consequences for species in each habitat type. Dormancy is often understood as a mechanism for persisting in the face of temporal variability but may serve as a means of traversing unsuitable habitat in patchy systems, warranting its consideration in estimates of habitat connectivity.
Aim
The influence of species phylogenetic relatedness on the formation of insular assemblages remains understudied in functional island biogeography, especially for terrestrial habitat islands (i.e. distinct habitat patches embedded in a matrix that differ in the prevailing environmental conditions). Here, we tested three eco‐evolutionary hypotheses: (1) functional specialization of species (i.e. specialism) is associated with phylogenetic clustering at the habitat archipelago scale, (2) such clustering increases with insularity at the habitat island scale and (3) traits indicative of effective local persistence strategies shape island specialism.
Location
Terrestrial habitat islands, Europe (Fens in the Western Carpathians, Outcrops in Moravia and Mountaintops in the Cantabrian Range).
Taxon
Angiosperms.
Methods
We assessed the phylogenetic relatedness of habitat specialists in three different archipelagos composed of terrestrial habitat islands based on phylogenetic signals and phylogenetic diversity (PD) measures. We estimated the effect of insularity on PD using linear models and the effect of persistence traits on specialism using phylogenetic logistic regressions.
Results
Our hypotheses were largely not supported. Outcrop and mountaintop specialist assemblages did not exhibit any phylogenetic structuring, whereas fen specialists were clustered at the archipelago scale. Therefore, insularity seems not to act as a selective force for phylogenetic structure, and ecologically important persistence traits do not operate as precursors of specialism.
Main Conclusions
Our results show that species phylogenetic relatedness plays a minor role in shaping habitat island specialist assemblages. Furthermore, the effects of phylogenetic relatedness on assemblages of island specialists are system and scale dependent. Finally, accounting for species' phylogenetic relatedness on persistence traits yielded results similar to previous studies, which corroborates the positive relationship between insularity and functional traits (indicative of enhanced plant persistence abilities with increasing within‐archipelago insularity).
Description
This publication, Methods and Measurements of Periphyton Communities: A Review, was sponsored by the American Society for Testing and Materials through its Committee D19 on Water. R. L. Weitzel, Hazleton Environmental Sciences Corporation, served as editor of this publication.
Description
Fifteen peer-reviewed papers emphasize the use of biological function couple with biological structure information to predict the effects of anthropogenic stress on aquatic communities and ecosystems.
The general dynamic model (GDM) of oceanic island biogeography views oceanic islands predominantly as sinks rather than sources of dispersing lineages. To test this, we conducted a biogeographic analysis of a highly successful insular plant taxon, Cyrtandra , and inferred the directionality of dispersal and founder events throughout the four biogeographical units of the Indo‐Australian Archipelago (IAA), namely Sunda, Wallacea, Philippines, and Sahul. Sunda was recovered as the major source area, followed by Wallacea, a system of oceanic islands. The relatively high number of events originating from Wallacea is attributed to its central location in the IAA and its complex geological history selecting for increased dispersibility. We also tested if diversification dynamics in Cyrtandra follow predictions of adaptive radiation, which is the dominant process as per the GDM. Diversification dynamics of dispersing lineages of Cyrtandra in the Southeast Asian grade showed early bursts followed by a plateau, which is consistent with adaptive radiation. We did not detect signals of diversity‐dependent diversification, and this is attributed to Southeast Asian cyrtandras occupying various niche spaces, evident by their wide morphological range in habit and floral characters. The Pacific clade, which arrived at the immaturity phase of the Pacific Islands, showed diversification dynamics predicted by the island immaturity speciation pulse model (IISP), wherein rates increase exponentially, and their morphological range is controlled by the least action effect favoring woodiness and fleshy fruits. Our study provides a first step toward a framework for investigating diversification dynamics as predicted by the GDM in highly successful insular taxa.
Small islands lack predators because species at higher trophic levels often cannot survive. However, two top predators—the Iriomote cat Prionailurus bengalensis iriomotensis , and the Crested Serpent Eagle Spilornis cheela perplexus —live on small Iriomotejima Island in the Ryukyu Archipelago. To understand how these predators coexist on the island with limited resources, we focused on their seasonal diets which are considered crucial for survival in such an island ecosystem. To compare the diets of them, we used DNA metabarcoding analysis of their fecal samples. In the summer, we identified 16 prey items from Iriomote cat fecal samples, and 15 from Crested Serpent Eagle fecal samples. In the winter, we identified 37 and 14 prey items, respectively. Using a non-metric multidimensional scaling and a permutational multivariate analysis of variance, our study reveals significant differences in the diet composition at the order level between the predators during both seasons. Furthermore, although some prey items at the species-to-order level overlapped between them, the frequency of occurrence of most prey items differed in both seasons. These results suggest that this difference in diets was one of the reasons why the Iriomote cat and the Crested Serpent Eagle coexisted on such a small island.
This article highlights the importance of terminology in ecology as a fundamental tool for clear and objective communication among scientists, as well as for standardizing study methods and techniques used by ecologists. Terminology refers to a set of terms, concepts, and definitions that are established and accepted by professionals in the field, enabling precise descriptions of species, ecosystems, and ecological processes. However, it is important to note that terminology in ecology is constantly evolving, and it is essential for ecological professionals to stay up to date with changes to contribute to the advancement of science. Understanding the historical process of ecological terminologies is also necessary to comprehend their meanings and how their interactions can affect the understanding of ecology itself. In this sense, we have provided a historical contextualization of several important concepts in community ecology, such as biodiversity, trophic levels, ecological niches, ecological guilds, and functional groups. We have also made comparisons and differentiations between these concepts throughout the history of these terms.
Context
Landscape ecology is endowed with a wealth of accumulated insights into how spatial, ecological and social research can be fruitfully combined and synthesised. This has the potential to contribute significantly to how cultural landscapes are observed, analysed, conceptualised and explained.
Objectives
This article provides an overview of theories in landscape ecology relevant to the study of cultural landscapes. Based on a review of selected contributions formulated since the field's first inception, it is outlined how theory was developed within the field and how proven methods of theory generation can inspire further development.
Methods
A systematic review covering historical and contemporary theoretical contributions to landscape ecology was conducted. Theories were analysed to uncover by what methods they were formulated. On this basis, an overview of theories in landscape ecology relevant to the study of cultural landscapes was developed.
Results
A total of 32 theories were included in the review and described. Four pathways of theory development characteristic for the way knowledge is accumulated in landscape ecology were identified. These pathways exhibit modes of knowledge transfer between observations and actions taking place in concrete empirical contexts, knowledge which is transferable across contexts, as well as generally applicable concepts. An annotated overview of primary and secondary sources is provided. Contemporary literature building on the theories was identified, linking sources of conceptual inspiration to the current state of the art.
Conclusions
The review illustrates that a wealth of complementary theories exists in the field, creating a condition of theoretical multiplicity. Key theories and tendencies for theory development are outlined, and it is discussed how theoretical advancement in the study of cultural landscapes may be improved.
Aim
Biodiversity on islands is commonly explained by a set of natural drivers such as area, isolation and habitat heterogeneity. However, constant human impact has led to considerable changes in island floras worldwide. This is reflected, among others, in increased numbers of non‐native species. Barrier islands are discrete land units, strongly influenced by humans and not displaying significant evolutionary dynamics. This makes them highly suitable for studying contemporary patterns of species richness and underlying processes. We aim to disentangle the effects of established natural and anthropogenic drivers on native and non‐native plant species richness at the example of 31 European barrier islands.
Location
31 North Sea barrier islands located off the Dutch, German and Danish coast.
Taxon
Native and non‐native plant species (spermatophytes and ferns).
Methods
Individual relationships of natural and anthropogenic drivers with native and non‐native plant species richness are analysed with generalised linear models (GLMs). We use structural equation models (SEMs) to additionally account for interrelations between drivers.
Results
Island area was the strongest predictor of native and non‐native plant species richness but affected richness mostly indirectly through habitat heterogeneity (non‐native species) and island inhabitants (native species). Isolation had a slight negative effect on native and non‐native plant species numbers on islands.
Main Conclusions
The richness of native and non‐native plant species on islands is associated with different drivers, that is, habitat heterogeneity and island inhabitants respectively. This might be caused by distinct underlying processes forming native and non‐native richness patterns. Area was confirmed to be the most important driver of species richness but acting primarily through other natural and anthropogenic drivers of plant species richness. We encourage considering both natural and anthropogenic drivers and their interrelatedness to explain contemporary biogeographic patterns of species richness.
Islands in the tropical Pacific Ocean are renowned for high biodiversity and endemism despite having relatively small landmasses. However, our knowledge of how this biodiversity is formed remains limited. The taxon cycle, where well‐dispersed, earlier colonizers become displaced from coastal to inland habitats by new waves of colonizers, producing isolated, range‐restricted species, has been proposed to explain current biodiversity patterns. Here, we integrate the outcomes of phylogenetic studies in the region to investigate the sources, age, number of colonizations, and diversification of 16 archipelagos in the tropical and subtropical South Pacific. We then evaluate whether the results support the taxon cycle as a plausible mechanism for these observations. We find that most species in the Pacific arrived less than 5 Mya from geographically close sources, suggesting that colonization by new taxa is a frequent and ongoing process. Therefore, our findings are broadly consistent with the theory of the Taxon Cycle, which posits that ongoing colonization results in the gradual displacement of established lineages. Only the oldest archipelagos, New Caledonia and Fiji, do not conform to this trend, having proportionally less recent colonization events, suggesting that the taxon cycle may slow on older islands. This conclusion is further validated by New Caledonia having lower diversification rate estimates than younger islands. We found that diversification rates across archipelagos are negatively correlated with area and age. Therefore, a taxon cycle that slows with island age appears to be a suitable concept for understanding the dynamic nature and biodiversity patterns of the Pacific Islands.
Aim
Island biological communities are considered to comprise non‐random assemblages from surrounding source pools, but whether they converge towards predictable structural properties remains unclear. Here, we (i) test whether insular communities of land snails converge towards similar functional and/or taxonomic properties and (ii) evaluate whether island functional diversity is determined by island biogeographical characteristics such as area and distance to the pool as well as human‐related variables.
Location
Sixty‐six continental Aegean islands.
Taxon
Land snails.
Methods
We compiled a database of two morphological traits with functional significance (shell height and width) for 163 island species and 1529 species from the major species pools. We quantified inter‐specific morphological dissimilarity between pairs of islands (turnover), using a modified index of the mean nearest taxon distance. We tested for functional and taxonomic convergence using null models and assessing whether overall mean turnover among islands and pairwise island‐by‐island turnover were lower than expected by chance. We performed multiple regression analyses to test whether functional diversity metrics scale with island biogeographical characteristics and human‐related variables.
Results
Our analyses provide strong evidence that communities of land snails across the Aegean islands converge towards non‐random functional properties and taxonomic structure. At the island level, a wide range of different shell shapes is observed, indicating greater functional richness than expected by chance. Regression analyses showed that island area is the only efficient predictor of functional diversity, indicating that available ecological/resource space is of central importance in driving the assembly of different shell shapes.
Main Conclusions
Our findings, consistent with previous studies of other taxa from oceanic islands, highlight that island species communities are not randomly assembled and display convergence in their functional and taxonomic composition. Integrating functional diversity metrics within biogeographic analyses has the potential to further our understanding of island biodiversity patterns.
Determining if ecological communities are saturated (have a limit to the number of species they can support) has important implications for understanding community assembly, species invasions, and climate change. However, previous studies have generally been limited to short time frames that overlook extinction debt and have not explicitly considered how functional trait diversity may mediate patterns of community saturation.
Here, we combine data from biodiversity surveys with functional and phylogenetic data to explore if the colonisation events after the Great American Biotic Interchange (closure of the Panamanian Isthmus) resulted in increases in species richness of communities of the snake family Dipsadidae. We determined the number and the direction of dispersal events between Central and South America by estimating ancestral areas based on a Bayesian time‐calibrated phylogenetic analysis. We then evaluated whether variation in community saturation was mediated by the functional similarity of six traits for the resident and colonizing snakes and/or local environmental conditions.
We found that colonised communities did not support more species than those that were not colonised. Moreover, we did not find an association between the functional diversity across sites and whether they were colonised by members from the lineages dispersing across the Isthmus or not. Instead, variation in species richness was predicted best by covariates such as time since colonisation and local environment.
Taken together, our results suggest that snake communities of the Dipsadidae across the neotropics are saturated. Moreover, our research highlights two important factors to consider in studies of community saturation: extinction debt and the functional differences and similarities in species' ecological roles.
Aim: Different hypothesis have been proposed to explain differences in species richness among islands. However, few studies have attempted to compare the explanatory power of multiple hypotheses using a large data set. Here, we analyse how different types of predictors (energetic/climatic, environmental heterogeneity, island biogeography and anthropogenic) affect variation in dung beetle species richness on Mediterranean and Macaronesian islands.
Location: Mediterranean and Macaronesian islands.
Taxon: Dung beetles.
Methods: Using a large data set of islands (n = 147), we extracted the species richness of dung beetles on each island using 362 bibliographic reference sources. We performed GLMs to analyse the relationship between the species richness of dung beetles and 11 explanatory variables (temperature, evapotranspiration, aridity, area, maximum elevation, connection to continent during LGM, geological origin, distance from continent, nearest continent, years since first human colonization and human density) representing four types of causal hypotheses. We also included as a covariate the number of published papers studying dung beetles as a surrogate of the survey/study effort carried out in each island.
Results: GLMs suggest that the years since first human colonization, the number of published papers and island area were the predictors with a higher explanatory capacity. The volcanic character of the islands and the distance from the mainland
had some relevance in the case of Scarabaeinae and Geotrupinae, and maximum
elevation appeared relevant in the species richness of Scarabaeinae and Aphodiidae. The anthropogenic and island biogeography hypotheses on the variation in species richness were the ones that have the strongest explanatory capacity, regardless of the inclusion of the surrogate of survey effort as a covariate in the models.
Main conclusions: The long history of human movements and agricultural activities
has facilitated the colonization of dung beetles and provided trophic resources for their persistence, leading to increased species richness. Thus, the importance of anthropogenic factors in shaping the biodiversity patterns of island biogeography cannot be ignored. These human-induced influences may play a fundamental role in altering the biogeographic patterns of islands, even overriding the importance of other variables. Consequently, our findings underline the profound impact of historical human actions on islands biodiversity.
Aim
We evaluated the effects of forest island size, isolation and area in the landscape driving temporal changes of insect biodiversity in a mountaintop forest archipelago. We expected that (i) in smaller, less isolated forest islands, changes in insect composition are more prominent, primarily driven by gains over time; (ii) more forest in the landscape leads to increased gains of vagile species over time, regardless of forest island size and isolation; (iii) less vagile groups undergo heterogenisation, while highly vagile groups experience homogenisation due to differing dispersal capabilities.
Location
Espinhaço Range Biosphere Reserve, Brazil.
Taxon
Insects.
Methods
We used ants, dung beetles, bees, wasps and butterflies as study models to represent a gradient of low-to-high dispersal capability. We evaluated the colonisation- and extirpation-resultant components of temporal β-diversity using area- and isolation-related variables as predictors.
Results
Distinct colonisation- and extirpation-resultant homogenisation and heterogenisation processes are acting according to each insect group, likely due to different dispersal capabilities. Species losses dominated in ants, with widespread and rare species being lost. Butterflies gained species, represented mainly by widespread species, leading to an increased colonisation-resultant homogenisation. Distance to neighbouring forest islands was the underlying predictor affecting the temporal β-diversity of insect groups, and also species gains and losses but differently according to the survey period. Effects of the forest amount in the landscape increased the temporal β-diversity of bees and butterflies but decreased that of ants, dung beetles and wasps.
Main Conclusions
These findings provide valuable biogeographic insights into the complex interactions between forest island characteristics, landscape attributes, and dispersal capabilities that shape the temporal dynamics of insect biodiversity on mountaintops. Conserving the forest amount in the landscape and keeping forest connectivity among forest islands are necessary because the temporal dynamics of local colonisation and extirpation can depend on the organisms' dispersal capability.
Undisturbed ant faunas of islands in the Moluccas-Melanesian arc are for the most part "saturated," that is, approach a size that is correlated closely with the landmass of the island but only weakly with its geographic location (figure 1). In the Ponerinae and Cerapachyinae combined the saturation level can be expressed approximately as F=3A0.6, where F is the number of species in the fauna and A the area of the island in square miles. Interspecific competition, involving some degree of colonial warfare, plays a major role in the determination of the saturation curve. It deploys the distribution of some ant species into mosaic patterns and increases the diversification of local faunas. Perhaps because of the complex nature of the Melanesian fauna, differences between local faunas appear that give the subjective impression of randomness. Despite the action of species exclusion, the size of local faunas occurring within a set sample area increases with the total size of the island (figure 2). Water gaps br...
1. A distinction is made between opportunistic and equilibrium species. 2. There is little ecological interest in the relative abundances of opportunistic species, but such species abundances should frequently have a log-normal distribution. 3. The relative abundances of equilibrium species are of considerable ecological interest and frequently can be deduced from the assumption that increase in one species population results in a roughly equal decrease in the populations of other species. To make the formulae well-defined it is necessary to assume that the census-taker has sampled a small area and thus achieved a certain sort of randomness. 4. For bird populations, at least, discrepancies between observations and predictions are negligible except when the censused area is compounded from different habitats. The discrepancy is then partly due to the fact that common species in one habitat are more likely to be present in adjacent habitats than are rate ones.
Die Geschischte des Sundabogens Borntraeger Berlin
- B Rensch
RENSCH, B. 1936. Die Geschischte des Sundabogens. Borntraeger, Berlin.
Darwin's finches, an essay on the general biological theory of evolution
- D Lack
LACK, D. 1947. Darwin's finches, an essay on
the general biological theory of evolution.
Cambridge University Press.
Die Vögel von Celebes
- Stresemann
Die Vogelwelt Polynesiens. Mitt
- E Mayr
MAYR, E. 1933. Die Vogelwelt Polynesiens.
Mitt. Zool. Mus. Berlin, 19: 306-323.
Die Vogelwelt Polynesiens
- Mayr
The zoogeographic position of the Hawaiian Islands
- Mayr
--. 1943. The zoogeographic position of the
Hawaiian Islands. Condor, 45: 45-48.