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Journal articleGumbs R, Scott O, Bates R, et al., 2024,
Global conservation status of the jawed vertebrate Tree of Life
, Nature Communications, Vol: 15, ISSN: 2041-1723Human-driven extinction threatens entire lineages across the Tree of Life. Here we assess the conservation status of jawed vertebrate evolutionary history, using three policy-relevant approaches. First, we calculate an index of threat to overall evolutionary history, showing that we expect to lose 86-150 billion years (11-19%) of jawed vertebrate evolutionary history over the next 50-500 years. Second, we rank jawed vertebrate species by their EDGE scores to identify the highest priorities for species-focused conservation of evolutionary history, finding that chondrichthyans, ray-finned fish and testudines rank highest of all jawed vertebrates. Third, we assess the conservation status of jawed vertebrate families. We found that species within monotypic families are more likely to be threatened and more likely to be in decline than other species. We provide a baseline for the status of families at risk of extinction to catalyse conservation action. This work continues a trend of highlighting neglected groups—such as testudines, crocodylians, amphibians and chondrichthyans—as conservation priorities from a phylogenetic perspective.
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ReportMoffett E, Gayford J, Woodward G, et al., 2024,
Biodiversity and ecosystem function: a global analysis of trends
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Journal articleNeyret M, Le Provost G, Boesing AL, et al., 2024,
A slow-fast trait continuum at the whole community level in relation to land-use intensification
, NATURE COMMUNICATIONS, Vol: 15 -
Journal articleDrury JP, Clavel J, Tobias JA, et al., 2024,
Limited ecological opportunity influences the tempo of morphological evolution in birds
, Current Biology, Vol: 34, Pages: 661-669.E4, ISSN: 0960-9822According to classic models of lineage diversification and adaptive radiation, phenotypic evolution should accelerate in the context of ecological opportunity and slow down when niches become saturated.1,2 However, only weak support for these ideas has been found in nature, perhaps because most analyses make the biologically unrealistic assumption that clade members contribute equally to reducing ecological opportunity, even when they occur in different continents or specialize on different habitats and diets. To view this problem through a different lens, we adapted a new phylogenetic modeling approach that accounts for the fact that competition for ecological opportunity only occurs between species that coexist and share similar habitats and diets. Applying this method to trait data for nearly all extant species of landbirds,3 we find a widespread signature of decelerating trait evolution in lineages adapted to similar habitats or diets. The strength of this pattern was consistent across latitudes when comparing tropical and temperate assemblages. Our results provide little support for the idea that increased diversity and tighter packing of niches accentuates evolutionary slowdowns in the tropics and instead suggest that limited ecological opportunity can be an important factor determining the rate of morphological diversification at a global scale.
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Journal articleLiu Y, Olsson A, Larva T, et al., 2024,
Genomic variation in montane bumblebees in Scandinavia: high levels of intraspecific diversity despite population vulnerability.
, Molecular Ecology, Vol: 33, ISSN: 0962-1083Populations of many bumblebee species are declining, with distributions shifting northwards to track suitable climates. Climate change is considered a major contributing factor. Arctic species are particularly vulnerable as they cannot shift further north, making assessment of their population viability important. Analysis of levels of whole-genome variation is a powerful way to analyse population declines and fragmentation. Here, we use genome sequencing to analyse genetic variation in seven species of bumblebee from the Scandinavian mountains, including two classified as vulnerable. We sequenced 333 samples from across the ranges of these species in Sweden. Estimates of effective population size (NE ) vary from ~55,000 for species with restricted high alpine distributions to 220,000 for more widespread species. Population fragmentation is generally very low or undetectable over large distances in the mountains, suggesting an absence of barriers to gene flow. The relatively high NE and low population structure indicate that none of the species are at immediate risk of negative genetic effects caused by high levels of genetic drift. However, reconstruction of historical fluctuations in NE indicates that the arctic specialist species Bombus hyperboreus has experienced population declines since the last ice age and we detected one highly inbred diploid male of this species close to the southern limit of its range, potentially indicating elevated genetic load. Although the levels of genetic variation in montane bumblebee populations are currently relatively high, their ranges are predicted to shrink drastically due to the effects of climate change and monitoring is essential to detect future population declines.
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Journal articleGranville NR, Barclay MVL, Boyle MJW, et al., 2024,
Resilience of tropical invertebrate community assembly processes to a gradient of land use intensity
, OIKOS, Vol: 2024, ISSN: 0030-1299Understanding how community assembly processes drive biodiversity patterns is a central goal of community ecology. While it is generally accepted that ecological communities are assembled by both stochastic and deterministic processes, quantifying their relative importance remains challenging. Few studies have investigated how the relative importance of stochastic and deterministic community assembly processes vary among taxa and along gradients of habitat degradation. Using data on 1645 arthropod species across seven taxonomic groups in Malaysian Borneo, we quantified the importance of ecological stochasticity and of a suite of community assembly processes across a gradient of logging intensity. The relationship between logging and community assembly varied depending on the specific combination of taxa and stochasticity metric used, but, in general, the processes that govern invertebrate community assembly were remarkably robust to changes in land use intensity.
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Journal articleCruz-Silva E, Harrion SP, Prentice IC, et al., 2024,
Holocene vegetation dynamics of the Eastern Mediterranean region: old controversies addressed by a new analysis
, Journal of Biogeography, Vol: 51, Pages: 294-310, ISSN: 0305-0270Aim:We reconstruct vegetation changes since 12 ky in the Eastern Mediterranean to examine four features of the regional vegetation history that are controversial: the extent of non-analogue vegetation assemblages in the transition from the Late Glacial to the early Holocene, the synchroneity of postglacial forest expansion, the geographical extent of temperate deciduous forest during the mid-Holocene and the timing and trigger for the re-establishment of drought-tolerant vegetation during the late Holocene.Location:The Eastern Mediterranean–Black Sea Caspian Corridor.Taxon:Vascular plants.Methods:We reconstruct vegetation changes for 122 fossil pollen records using a method that accounts for within-biome variability in pollen taxon abundance to determine the biome with which a sample has greatest affinity. Per-biome affinity threshold values were used to identify samples that do not belong to any modern biome. We apply time series analysis and mapping to examine space and time changes.Results:Sites with non-analogue vegetation were most common between 11.5 and 9.5 ky and mostly in the Carpathians. The transition from open vegetation to forest occurred at 10.64 ± 0.65 ky across the whole region. Temperate deciduous forest was not more extensive at 6 ky; maximum expansion occurred between 5.5 and 5 ky. Expansion of forest occurred between c. 4 and 2.8 k, followed by an abrupt decrease and a subsequent recovery. This pattern is not consistent with a systematic decline of forest towards more drought-tolerant vegetation in the late Holocene but is consistent with centennial-scale speleothem patterns linked to variations in moisture availability.Main Conclusions:We show the occurrence of non-analogue vegetation types peaked during early Holocene, forest expansion was synchronous across the region and there was an expansion of moisture-demanding temperate trees around 5.5 to 5 ky. There is no signal of a continuous late Holocene aridificat
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Journal articleHatfield JH, Banks-Leite C, Barlow J, et al., 2024,
Constraints on avian seed dispersal reduce potential for resilience in degraded tropical forests
, FUNCTIONAL ECOLOGY, Vol: 38, Pages: 315-326, ISSN: 0269-8463 -
Journal articleKeeping T, Harrison SP, Prentice IC, 2024,
Modelling the daily probability of wildfire occurrence in the contiguous United States
, Environmental Research Letters, Vol: 19, ISSN: 1748-9326The development of a high-quality wildfire occurrence model is an essential component in mapping present wildfire risk, and in projecting future wildfire dynamics with climate and land-use change. Here, we develop a new model for predicting the daily probability of wildfire occurrence at 0.1° (∼10 km) spatial resolution by adapting a generalised linear modelling (GLM) approach to include improvements to the variable selection procedure, identification of the range over which specific predictors are influential, and the minimisation of compression, applied in an ensemble of model runs. We develop and test the model using data from the contiguous United States. The ensemble performed well in predicting the mean geospatial patterns of fire occurrence, the interannual variability in the number of fires, and the regional variation in the seasonal cycle of wildfire. Model runs gave an area under the receiver operating characteristic curve (AUC) of 0.85–0.88, indicating good predictive power. The ensemble of runs provides insight into the key predictors for wildfire occurrence in the contiguous United States. The methodology, though developed for the United States, is globally implementable.
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Journal articleMolnar Z, Aumeeruddy-Thomas Y, Babai D, et al., 2024,
Towards richer knowledge partnerships between ecology and ethnoecology
, TRENDS IN ECOLOGY & EVOLUTION, Vol: 39, Pages: 109-115, ISSN: 0169-5347 -
Journal articleCantwell-Jones A, Tylianakis J, Larson K, et al., 2024,
Using individual-based trait frequency distributions to forecast plant-pollinator network responses to environmental change
, Ecology Letters, Vol: 27, ISSN: 1461-023XDetermining how and why organisms interact is fundamental to understanding ecosystem responses to future environmental change. To assess the impact on plant-pollinator interactions, recent studies have examined how the effects of environmental change on individual interactions accumulate to generate species-level responses. Here, we review recent developments in using plant-pollinator networks of interacting individuals along with their functional traits, where individuals are nested within species nodes. We highlight how these individual-level, trait-based networks connect intraspecific trait variation (as frequency distributions of multiple traits) with dynamic responses within plant-pollinator communities. This approach can better explain interaction plasticity, and changes to interaction probabilities and network structure over spatiotemporal or other environmental gradients. We argue that only through appreciating such trait-based interaction plasticity can we accurately forecast the potential vulnerability of interactions to future environmental change. We follow this with general guidance on how future studies can collect and analyse high-resolution interaction and trait data, with the hope of improving predictions of future plant-pollinator network responses for targeted and effective conservation.
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Journal articleSavolainen V, Bailey NW, Diamond L, et al., 2024,
A broader cultural view is necessary to study the evolution of sexual orientation
, Nature Ecology and Evolution, Vol: 8, Pages: 181-183, ISSN: 2397-334XThe causation of sexual orientation is likely to be complex and influenced by multiple factors1. We advocate incorporating a broader cultural view into evolutionary andgenetic studies to account for differences in how sexual orientation is experienced, expressed, and understood in both human and non-human animals.
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Book chapterPrentice IC, Cowling SA, 2024,
Dynamic Global Vegetation Models
, Encyclopedia of Biodiversity, Third Edition: Volume 1-7Dynamic global vegetation models encapsulate our knowledge of plant and ecosystem function. They have many potential applications but not all of these are well developed, and large differences among model predictions are a concern. Fields of application include analysis of land–atmosphere biophysical interactions, carbon and water cycling, climate impacts on vegetation structure, fire, atmospheric trace gas composition, Quaternary vegetation and environmental changes, and ecosystem structure and function through Earth history. There is scope to improve models using a wider range of information from plant functional ecology, ecophysiology, environmental remote sensing, and atmospheric measurement, Quaternary paleoecology, and paleobotany.
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Journal articleKawaguchi S, Atkinson A, Bahlburg D, et al., 2024,
Climate change impacts on Antarctic krill behaviour and population dynamics
, NATURE REVIEWS EARTH & ENVIRONMENT, Vol: 5, Pages: 43-58 -
Journal articleRen Y, Wang H, Harrison SP, et al., 2024,
Reduced global plant respiration due to the acclimation of leaf dark respiration coupled to photosynthesis
, New Phytologist, Vol: 241, Pages: 578-591, ISSN: 0028-646XLeaf dark respiration (Rd) acclimates to environmental changes. However, the magnitude, controls and time scales of acclimation remain unclear and are inconsistently treated in ecosystem models. We hypothesized that Rd and Rubisco carboxylation capacity (Vcmax) at 25°C (Rd,25, Vcmax,25) are coordinated so that Rd,25 variations support Vcmax,25 at a level allowing full light use, with Vcmax,25 reflecting daytime conditions (for photosynthesis), and Rd,25/Vcmax,25 reflecting night-time conditions (for starch degradation and sucrose export). We tested this hypothesis temporally using a 5-yr warming experiment, and spatially using an extensive field-measurement data set. We compared the results to three published alternatives: Rd,25 declines linearly with daily average prior temperature; Rd at average prior night temperatures tends towards a constant value; and Rd,25/Vcmax,25 is constant. Our hypothesis accounted for more variation in observed Rd,25 over time (R2 = 0.74) and space (R2 = 0.68) than the alternatives. Night-time temperature dominated the seasonal time-course of Rd, with an apparent response time scale of c. 2 wk. Vcmax dominated the spatial patterns. Our acclimation hypothesis results in a smaller increase in global Rd in response to rising CO2 and warming than is projected by the two of three alternative hypotheses, and by current models.
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Journal articleGonzalez A, Vihervaara P, Balvanera P, et al., 2024,
A global biodiversity observing system to unite monitoring and guide action (AUG, 10.1038/s41559-023-02171-0, 2023)
, NATURE ECOLOGY & EVOLUTION, Vol: 8, Pages: 175-175, ISSN: 2397-334X -
Journal articlePreston-Allen RGG, Hakkinen H, Canellas-Dols L, et al., 2024,
Geography, taxonomy, extinction risk and exposure of fully migratory birds to droughts and cyclones
, GLOBAL ECOLOGY AND BIOGEOGRAPHY, Vol: 33, Pages: 63-73, ISSN: 1466-822X -
Journal articleChow LJ, Nesbit ML, Hill T, et al., 2024,
Identification of fungi isolated from commercial bumblebee colonies
, PeerJ, Vol: 12, ISSN: 2167-8359Fungi can have important beneficial and detrimental effects on animals, yet our understanding of the diversity and function of most bee-associated fungi is poor. Over 2 million bumblebee colonies are traded globally every year, but the presence and transport of viable fungi within them is unknown. Here, we explored whether any culturable fungi could be isolated from commercial bumblebee nests. We collected samples of various substrates from within 14 bumblebee colonies, including the honey, honey cup wall, egg cup wall, and frass then placed them on agar and recorded any growth. Fungal morphotypes were then subcultured and their ITS region sequenced for identification. Overall, we cultured 11 fungal species from the various nest substrates. These included both pathogenic and non-pathogenic fungi, such as Aspergillus sp., Penicillium sp., and Candida sp. Our results provide the first insights into the diversity of viable fungal communities in commercial bumblebee nests. Further research is needed to determine if these fungi are unique to commercial colonies or prevalent in wild bumblebee nests, and crucially to determine the ecological and evolutionary implications of these fungi in host colonies.
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Journal articleCoathup M, Savolainen V, 2024,
Ecological speciation in sympatric palms: 5. Evidence for pleiotropic speciation genes using gene knockout and high-throughput phenotyping
, Evolutionary Journal of the Linnean Society, Vol: 3, ISSN: 2752-938XTheoretical models predict that sympatric, ecological speciation may be facilitated more readily when so-called ‘magic traits’ are present, linking traits under divergent selection with assortative mating. Such traits might be encoded by pleiotropic genes, that is, genes that affect multiple, apparently unrelated, phenotypes. However, few convincing examples of sympatric speciation exist, and empirical evidence for the role of magic traits in driving such speciation is rare. One of the strongest cases of sympatric speciation is the Howea palms of Lord Howe Island, Australia, comprising the sister species H. belmoreana and H. forsteriana, which have diverged due to soil substrate preferences and flowering time displacement. By carrying out high-throughput phenotyping experiments using 1,830 Arabidopsis thaliana plants with knockouts of candidate Howea ‘speciation genes’, here we investigate the role that pleiotropy may have played in the speciation process. We identify several genes that show signatures of adaptive divergence between the Howea species and demonstrate pleiotropic roles in soil stress tolerance and flowering time, consistent with the Howea speciation scenario – notably, Howea orthologs of the A. thaliana loci At2-MMP, DCL1, RCD1, SAL1, and SIZ1. Empirical evidence is provided, therefore, for a range of pleiotropic genes with the potential to have driven sympatric speciation by generating magic traits which link divergent selection to non-random mating.
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Journal articleGonzalez-Ferreras AM, Barquin J, Blyth PSA, et al., 2023,
Chronic exposure to environmental temperature attenuates the thermal sensitivity of salmonids
, NATURE COMMUNICATIONS, Vol: 14 -
Book chapterShocket M, Caldwell J, Huxley P, et al., 2023,
Modelling the effects of climate and climate change on transmission of vector-borne disease
, Planetary health approaches to understand and control vector-borne diseases, Editors: Fornace, Conn, Mureb, Chaves, Logan, Publisher: BRILL, Pages: 253-318, ISBN: 9789004688650Mathematical and statistical models are critical tools for both understanding how climate can influence patterns of vector-borne disease transmission, and predicting how climate change might affect these patterns in the future. This chapter focuses primarily on quantitative approaches for modelling the effects of climate on mosquito-borne disease (MBD), although we also briefly consider tick-borne disease. We initially describe how the biological mechanisms that contribute to transmission of vector-borne disease can respond to changes in climate and other environmental factors. Importantly, transmission of MBD responds nonlinearly over gradients of both temperature and rainfall. When building or interpreting models for the effects of climate on MBD dynamics, it is important to consider that the effects of temperature and rainfall on disease may be positive, negative, or both depending on circumstance. This context-dependence can limit the transferability of models beyond the setting in which they were fit. Next, we provide an overview of important concepts and approaches for modelling vector-borne diseases using mechanistic and statistical models. This includes the most commonly used modelling methods, techniques for model evaluation and validation, and climate re-analysis products used as model predictors. The best choices of methods for model construction and evaluation depend on the goals of the model and the structure of the underlying data, including their spatial and temporal scales. Then, we explore three case studies of MBD in more detail and use them to illustrate representative modelling approaches across a gradient of spatiotemporal scales: (1) local time series models of dengue fever in San Juan, Puerto Rico; (2) regional models of West Nile virus in the United States; and (3) continental and global models for how climate change may impact future transmission risk for malaria and dengue fever. Finally, we note some key challenges, knowledge gaps, and res
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Journal articleEberhart-Hertel LJ, Rodrigues LF, Krietsch J, et al., 2023,
Egg size variation in the context of polyandry: a case study using long-term field data from snowy plovers
, EVOLUTION, Vol: 77, Pages: 2590-2605, ISSN: 0014-3820 -
Journal articleRuehr S, Keenan TF, Williams C, et al., 2023,
Publisher Correction: Evidence and attribution of the enhanced land carbon sink (Nature Reviews Earth & Environment, (2023), 4, 8, (518-534), 10.1038/s43017-023-00456-3)
, Nature Reviews Earth and Environment, Vol: 4Correction to: Nature Reviews Earth & Environment, published online 25 July 2023. In the version of the article initially published, the y-axis labels in Fig. 7b, now reading “+” and “–”, read “234” and “254”, respectively. This has been corrected in the HTML and PDF versions of the article.
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Journal articleTudge SJ, Harris ZM, Murphy RJ, et al., 2023,
Global trends in biodiversity with tree plantation age
, GLOBAL ECOLOGY AND CONSERVATION, Vol: 48 -
Journal articleDelabre I, Lyons-White J, Melot C, et al., 2023,
Should I stay or should I go? Understanding stakeholder dis/engagement for deforestation-free palm oil
, Business Strategy and the Environment, Vol: 32, Pages: 5128-5145, ISSN: 0964-4733Addressing tropical deforestation in the palm oil sector involves a diverse range of stakeholders who engage or disengage with each other. Palm oil global value chain (GVC) firms (plantation companies, traders and processors, and consumer goods manufacturers and retailers), as well as nongovernmental organisations, financial institutions, consultancies and certification bodies, pursue their respective organisations' agendas through engagement practices, including through coalitions, in a palm oil sustainability network (POSN). Building on interviews with different stakeholder groups, this qualitative study characterises and critically analyses ‘stakeholder engagement’ by examining (1) the priority targets for engagement among different POSN stakeholders, (2) how mechanisms and tools are used in POSN stakeholder engagement or disengagement for addressing deforestation, and (3) the implications of stakeholder engagement or disengagement for addressing deforestation. Engagement and disengagement practices are shaped by and reshape GVC governance, with powerful stakeholders emerging as knowledge brokers and norm setters, raising important challenges for how deforestation is addressed.
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Journal articlePeng Y, Prentice IC, Bloomfield KJ, et al., 2023,
Global terrestrial nitrogen uptake and nitrogen use efficiency
, Journal of Ecology, Vol: 111, Pages: 2676-2693, ISSN: 0022-04771. Plant biomass production (BP), nitrogen uptake (Nup) and their ratio, nitrogen use efficiency (NUE), must be quantified to understand how nitrogen (N) cycling constrains terrestrial carbon (C) uptake. But the controls of key plant processes determining Nup and NUE, including BP, C and N allocation, tissue C:N ratios and N resorption efficiency (NRE), remain poorly known. 2. We compiled measurements from 804 forest and grassland sites and derived regression models for each of these processes with growth temperature, vapour pressure deficit, stand age, soil C:N ratio, fAPAR (remotely sensed fraction of photosynthetically active radiation absorbed by green vegetation) and growing-season average daily incident photosynthetic photon flux density (gPPFD) (effectively the seasonal concentration of light availability, which increases polewards) as predictors. An empirical model for leaf N was based on optimal photosynthetic capacity (a function of gPPFD and climate) and observed leaf mass-per-area. The models were used to produce global maps of Nup and NUE. 3. Global BP was estimated as 72 Pg C/yr; Nup as 950 Tg N/yr; and NUE as 76 gC/gN. Forest BP was found to increase with growth temperature and fAPAR and to decrease with stand age, soil C:N ratio and gPPFD. Forest NUE is controlled primarily by climate through its effect on C allocation – especially to leaves, being richer in N than other tissues. NUE is greater in colder climates, where N is less readily available, because belowground allocation is increased. NUE is also greater in drier climates because leaf allocation is reduced. NRE is enhanced (further promoting NUE) in both cold and dry climates. 4. These findings can provide observationally based benchmarks for model representations of C–N cycle coupling. State-of-the-art vegetation models in the TRENDY ensemble showed variable performance against these benchmarks, and models including coupled C–N cycling produced relatively poor simulations o
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Journal articleKeenan TF, Luo X, Stocker BD, et al., 2023,
A constraint on historic growth in global photosynthesis due to rising CO2
, Nature Climate Change, Vol: 13, Pages: 1376-1381, ISSN: 1758-678XTheory predicts that rising CO2 increases global photosynthesis, a process known as CO2 fertilization, and that this is responsible for a large proportion of the current terrestrial carbon sink. The estimated magnitude of the historic CO2 fertilization, however, differs by an order ofmagnitude between long-term proxies, remote sensing-based estimates and terrestrial biosphere models. Here we constrain the likely historic effect of CO2 on global photosynthesis by combining terrestrial biosphere models, ecological optimality theory, remote sensing approaches and an emergent constraint based on global carbon budget estimates. Our analysis suggests that CO2 fertilization increased global annual terrestrial photosynthesis by 13.5 ± 3.5%, or 15.9 ± 2.9 Pg C u(mean ± standard deviation) between 1981 and 2020. Our results help resolve conflicting estimates of the historic sensitivity of global terrestrial photosynthesis to CO2 and highlight the large impact anthropogenic emissions have had on ecosystems worldwide.
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Journal articleDimitrov D, Xu X, Su X, et al., 2023,
Diversification of flowering plants in space and time
, NATURE COMMUNICATIONS, Vol: 14 -
Journal articleXu H, Wang H, Prentice IC, et al., 2023,
Leaf carbon and nitrogen stoichiometric variation alongenvironmental gradients
, Biogeosciences, Vol: 20, Pages: 4511-4525, ISSN: 1726-4170Leaf stoichiometric traits are central to ecosystem function and biogeochemical cycling, yet no accepted theory predicts their variation along environmental gradients. Using data in the China Plant Trait Database version 2, we aimed to characterize variation in leaf carbon and nitrogen per unit mass (Cmass, Nmass) and their ratio, and to test an eco-evolutionary optimality model for Nmass. Community-mean trait values were related to climate variables by multiple linear regression. Climatic optima and tolerances of major genera were estimated; Pagel’s λ was used to quantify phylogenetic controls, and Bayesian phylogenetic linear mixed models to assess the contributions of climate, species identity and phylogeny. Optimality-based predictions of community-mean Nmass were compared to observed values. All traits showed strong phylogenetic signals. Climate explained only 18 % of C : N ratio variation among species but 45 % among communities, highlighting the role of taxonomic replacement in mediating community-level responses. Geographic distributions of deciduous taxa separated primarily by moisture, evergreens by temperature. Cmass increased with irradiance, but decreased with moisture and temperature. Nmass declined with all three variables. C : N ratio variations were dominated by Nmass. The coefficients relating Nmass to the ratio of maximum carboxylation capacity at 25 °C (Vcmax25) and leaf mass per area (Ma) were influenced by leaf area index. The optimality model captured 68 % and 53 % of variation between communities for Vcmax25 and Ma respectively, and 30 % for Nmass. We conclude that stoichiometric variations along climate gradients are achieved largely by environmental selection among species and clades with different characteristic trait values. Variations in leaf C : N ratio are mainly determined by Nmass, and optimality-based modelling shows useful predictive ability for community-mean Nmass. These findings should help to improve the repres
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Journal articleBrazeau M, Castiello M, El Fassi El Fehri A, et al., 2023,
Fossil evidence for a pharyngeal origin of the vertebrate pectoral girdle
, Nature, Vol: 623, Pages: 550-554, ISSN: 0028-0836The origin of vertebrate paired appendages is one of the most investigated and debated examples of evolutionary novelty. Paired appendages are widely considered key innovations that allowed new opportunities for controlled swimming and gill ventilation and were prerequisites for the eventual transition from water to land. The last 150 years of debate has been shaped by two contentious theories: the ventrolateral fin-fold hypothesis and the archipterygium hypothesis. The latter proposes that fins and girdles evolved from an ancestral gill arch. Although tantalizing developmental evidence has revived interest in this idea, it is apparently unsupported by fossil evidence. Here we present fossil evidence of a pharyngeal basis for the vertebrate shoulder girdle. We use CT scanning to reveal details of the braincase of Kolymaspis sibirica, a placoderm fish from the Early Devonian of Siberia that suggests a pharyngeal component of the shoulder. We combine these findings with refreshed comparative anatomy of placoderms and jawless outgroups to place the origin of the shoulder girdle on the sixth branchial arch. These findings provide a novel framework for understanding the origin of the pectoral girdle. Our new evidence clarifies the location of the presumptive head-trunk interface in jawless fishes and explains the constraint on branchial arch number in gnathostomes. The results revive a key aspect of the archipterygium hypothesis, but also reconciles it with the ventrolateral fin fold model.
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