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Journal articleDunning J, Burke T, Chan AHH, et al., 2023,
Opposite-sex associations are linked with annual fitness, but sociality is stable over lifetime
, Behavioral Ecology, Vol: 315, Pages: 315-324, ISSN: 1045-2249Animal sociality, an individual’s propensity to associate with others, has fitness consequences through mate choice, for example, directly, by increasing the pool of prospective partners, and indirectly through increased survival, and individuals benefit from both. Annually, fitness consequences are realized through increased mating success and subsequent fecundity. However, it remains unknown whether these consequences translate to lifetime fitness. Here, we quantified social associations and their link to fitness annually and over lifetime, using a multi-generational, genetic pedigree. We used social network analysis to calculate variables representing different aspects of an individual’s sociality. Sociality showed high within-individual repeatability. We found that birds with more opposite-sex associates had higher annual fitness than those with fewer, but this did not translate to lifetime fitness. Instead, for lifetime fitness, we found evidence for stabilizing selection on opposite-sex sociality, and sociality in general, suggesting that reported benefits are only short-lived in a wild population, and that selection favors an average sociality.
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Journal articleOsborne OG, Dobreva MP, Papadopulos AST, et al., 2023,
Mapping the root systems of individual trees in a natural community using genotyping-by-sequencing
, New Phytologist, Vol: 238, Pages: 1305-1317, ISSN: 0028-646X•The architecture of root systems is an important driver of plant fitness, competition and ecosystem processes. However, the methodological difficulty of mapping roots hampers the study of these processes. Existing approaches to match individual plants to belowground samples are low throughput and species specific. Here, we developed a scalable sequencing-based method to map the root systems of individual trees across multiple species. We successfully applied it to a tropical dry forest community in the Brazilian Caatinga containing 14 species. • We sequenced all 42 individual shrubs and trees in a 14 × 14 m plot using double-digest restriction site-associated sequencing (ddRADseq). We identified species-specific markers and individual-specific haplotypes from the data. We matched these markers to the ddRADseq data from 100 mixed root samples from across the centre (10 × 10 m) of the plot at four different depths using a newly developed R package. • We identified individual root samples for all species and all but one individual. There was a strong significant correlation between belowground and aboveground size measurements, and we also detected significant species-level root-depth preference for two species. • The method is more scalable and less labour intensive than the current techniques and is broadly applicable to ecology, forestry and agricultural biology.
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Journal articleCornford R, Spooner F, McRae L, et al., 2023,
Ongoing over-exploitation and delayed responses to environmental change highlight the urgency for action to promote vertebrate recoveries by 2030
, PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 290, ISSN: 0962-8452 -
Journal articleShen Y, Cai W, Prentice IC, et al., 2023,
Community abundance of resprouting in woody plants reflects fire return time, intensity, and type
, Forests, Vol: 14, Pages: 1-13, ISSN: 1999-4907Plants in fire-prone ecosystems have evolved a variety of mechanisms to resist or adapt to fire. Post-fire resprouting is a key adaptation that promotes rapid ecosystem recovery and hence has a major impact on the terrestrial carbon cycle. However, our understanding of how the incidence of resprouting varies in different fire regimes is largely qualitative. The increasing availability of plant trait data and plot-based species cover data provides an opportunity to quantify the relationships between fire-related traits and fire properties. We investigated the quantitative relationship between fire frequency (expressed as the fire return time) and the proportion of resprouters in woody plants using plot data on species cover from Australia and Europe. We also examined the relationship between the proportion of resprouters and gross primary production (GPP) and grass cover, where GPP was assumed to reflect fuel loads and hence fire intensity, while grass cover was considered to be an indicator of the likelihood of ground fire and the speed of fire spread, using generalised linear modelling. The proportion of resprouting species decreased significantly as the fire return time increased. When the fire return time was considered along with other aspects of the fire regime, the proportion of resprouters had significant negative relationships with the fire return time and grass cover and a significant positive relationship with GPP. These findings demonstrate that plants with the ability to resprout occur more often where fire regimes are characterised by high-frequency and high-intensity crown fires. Establishing quantitative relationships between the incidence of resprouting and the fire return time and fire type provides a basis for modelling resprouting as a consequence of the characteristics of the fire regime, which in turn makes it possible to model the consequences of changing fire regimes on ecosystem properties.
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Journal articleSantini L, Tobias JA, Callaghan C, et al., 2023,
Global patterns and predictors of avian population density
, GLOBAL ECOLOGY AND BIOGEOGRAPHY, ISSN: 1466-822X -
Journal articleLiu D, Semenchuk P, Essl F, et al., 2023,
The impact of land use on non-native species incidence and number in local assemblages worldwide
, NATURE COMMUNICATIONS, Vol: 14- Author Web Link
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- Citations: 5
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Journal articleWyer C, Brian H, Cator L, 2023,
Release from sexual selection leads to rapid genome-wide evolution in Aedes aegypti
, Current Biology, Vol: 33, Pages: 1351-1357.e5, ISSN: 0960-9822The yellow fever mosquito, Aedes aegypti, mates in flight as part of ephemeral aggregations termed swarms. Swarms contain many more males than females, and males are thought to be subject to intense sexual selection.1,2 However, which male traits are involved in mating success and the genetic basis of these traits remains unclear. We used an experimental evolution approach to measure genome-wide responses of Ae. aegypti evolved in the presence and absence of sexual selection. These data revealed for the first time how sexual selection shapes the genome of this important species. We found that populations evolved under sexual selection retained greater genetic similarity to the ancestral population and a higher effective population size than populations evolving without sexual selection. When we compared evolutionary regimes, we found that genes associated with chemosensation responded rapidly to the elimination of sexual selection. Knockdown of one high-confidence candidate gene identified in our analysis significantly decreased male insemination success, further suggesting that genes related to male sensory perception are under sexual selection. Several mosquito control technologies involve the release of males from captive populations into the wild. For these interventions to work, a released male must compete against wild males to successfully inseminate a female. Our results suggest that maintaining the intensity of sexual selection in captive populations used in mass-releases is important for sustaining both male competitive ability and overall genetic similarity to field populations.
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Journal articleLiu M, Shen Y, Gonzalez-Samperiz P, et al., 2023,
Holocene climates of the Iberian Penisula: pollen-based reconstructions of changes in the west-east gradient of temperature and moisture
, Climate of the Past, Vol: 19, Pages: 803-834, ISSN: 1814-9324The Iberian Peninsula is characterised by a steep west-east moisture gradient today, reflecting the dominance of maritime influences along the Atlantic coast and more Mediterranean-type climate further east. Holocene pollen records from the Peninsula suggest that this gradient was less steep during the mid-Holocene, possibly reflecting the impact of orbital changes on circulation and thus regional patterns in climate. Here we use 7214 pollen samples from 117 sites covering part or all of the last 12,000 years to reconstruct changes in seasonal temperature and in moisture across the Iberian Peninsula quantitatively. We show that there is an increasing trend in winter temperature at a regional scale, consistent with known changes in winter insolation. However, summer temperatures do not show the decreasing trend through the Holocene that would be expected if they were a direct response to insolation forcing. We show that summer temperature is strongly correlated with plant-available moisture (α), as measured by the ratio of actual evapotranspiration to equilibrium evapotranspiration, which declines through the Holocene. The reconstructions also confirm that the west-east gradient in moisture was considerably less steep than today during the mid-Holocene, indicating that atmospheric circulation changes (possibly driven by orbital changes) have been important determinants of the Holocene climate of the region.
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Journal articleGkourtsouli-Antoniadou I, Ewing SRR, Hudson G, et al., 2023,
Age-specific survival in an English Twite <i>Linaria flavirostris</i> population
, BIRD STUDY, Vol: 70, Pages: 59-63, ISSN: 0006-3657 -
Journal articleHowes B, Gonzalez-Suarez M, Jensen HJ, et al., 2023,
Deforestation alters species interactions
, NATURAL SCIENCES, Vol: 3, ISSN: 2698-6248 -
Journal articleHong P, Li Z, Yang Q, et al., 2023,
Functional traits and environment jointly determine the spatial scaling of population stability in North American birds
, ECOLOGY, Vol: 104, ISSN: 0012-9658 -
Journal articleLawson J, Rizos G, Jasinghe D, et al., 2023,
Automated acoustic detection of Geoffroy's spider monkey highlights tipping points of human disturbance
, PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 290, ISSN: 0962-8452- Author Web Link
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- Citations: 1
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Journal articleBloomfield K, van Hoolst R, Balzarolo M, et al., 2023,
Towards a general monitoring system for terrestrial primary production: a test spanning the European drought of 2018
, Remote Sensing, Vol: 15, Pages: 1-15, ISSN: 2072-4292(1) Land surface models require inputs of temperature and moisture variables to generate predictions of gross primary production (GPP). Differences between leaf and air temperature vary temporally and spatially and may be especially pronounced under conditions of low soil moisture availability. The Sentinel-3 satellite mission offers estimates of the land surface temperature (LST), which for vegetated pixels can be adopted as the canopy temperature. Could remotely sensed estimates of LST offer a parsimonious input to models by combining information on leaf temperature and hydration? (2) Using a light use efficiency model that requires only a handful of input variables, we generated GPP simulations for comparison with eddy-covariance inferred estimates available from flux sites within the Integrated Carbon Observation System. Remotely sensed LST and greenness data were input from Sentinel-3. Gridded air temperature data were obtained from the European Centre for Medium-Range Weather Forecasts. We chose the years 2018–2019 to exploit the natural experiment of a pronounced European drought. (3) Simulated GPP showed good agreement with flux-derived estimates. During dry conditions, simulations forced with LST performed better than those with air temperature for shrubland, grassland and savanna sites. (4) This study advances the prospect for a global GPP monitoring system that will rely primarily on remotely sensed inputs.
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ReportPreston-Allen R, Albini D, Barron L, et al., 2023,
Are urban areas hotspots for pollution from pet parasiticides?
, Are urban areas hotspots for pollution from pet parasiticides?, www.imperial.ac.uk/grantham, Publisher: Grantham Institute, Briefing Note 15This briefing considers the environmental impact of pet parasiticides, which are commonly used to kill parasites such as fleas and ticks. It reviews possible routes that chemicals from veterinary parasiticides enter the environment, what impacts they may have on natural ecosystems and how to balance the needs of domestic pets, people, and the environment.
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Journal articleFlintham E, Savolainen V, Mullon C, 2023,
Male harm offsets the demographic benefits of good genes
, Proceedings of the National Academy of Sciences of USA, Vol: 120, Pages: 1-9, ISSN: 0027-8424Sexual conflict can arise when males evolve traits that improve their mating success but in doing so harm females. By reducing female fitness, male harm can diminish offspring production in a population and even drive extinction. Current theory on harm is based on the assumption that an individual’s phenotype is solely determined by its genotype. But the expression of most sexually selected traits is also influenced by variation in biological condition (condition-dependent expression), such that individuals in better condition can express more extreme phenotypes. Here, we developed demographically explicit models of sexual conflict evolution where individuals vary in their condition. Because condition-dependent expression readily evolves for traits underlying sexual conflict, we show that conflict is more intense in populations where individuals are in better condition. Such intensified conflict reduces mean fitness and can thus generate a negative association between condition and population size. The impact of condition on demography is especially likely to be detrimental when the genetic basis of condition coevolves with sexual conflict. This occurs because sexual selection favors alleles that improve condition (the so-called good genes effect), producing feedback between condition and sexual conflict that drives the evolution of intense male harm. Our results indicate that in presence of male harm, the good genes effect in fact easily becomes detrimental to populations.
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Journal articleCantwell-Jones A, Larson K, Ward A, et al., 2023,
Mapping trait versus species turnover reveals spatiotemporal variation in functional redundancy and network robustness in a plant-pollinator community
, Functional Ecology, Vol: 37, Pages: 748-762, ISSN: 0269-8463Functional overlap among species (redundancy) is considered important in shaping competitive and mutualistic interactions that determine how communities respond to environmental change. Most studies view functional redundancy as static, yet traits within species—which ultimately shape functional redundancy—can vary over seasonal or spatial gradients. We therefore have limited understanding of how trait turnover within and between species could lead to changes in functional redundancy or how loss of traits could differentially impact mutualistic interactions depending on where and when the interactions occur in space and time. Using an Arctic bumblebee community as a case study, and 1277 individual measures from 14 species over three annual seasons, we quantified how inter- and intraspecific body-size turnover compared to species turnover with elevation and over the season. Coupling every individual and their trait with a plant visitation, we investigated how grouping individuals by a morphological trait or by species identity altered our assessment of network structure and how this differed in space and time. Finally, we tested how the sensitivity of the network in space and time differed when simulating extinction of nodes representing either morphological trait similarity or traditional species groups. This allowed us to explore the degree to which trait-based groups increase or decrease interaction redundancy relative to species-based nodes. We found that (i) groups of taxonomically and morphologically similar bees turn over in space and time independently from each other, with trait turnover being larger over the season; (ii) networks composed of nodes representing species versus morphologically similar bees were structured differently; and (iii) simulated loss of bee trait groups caused faster coextinction of bumblebee species and flowering plants than when bee taxonomic groups were lost. Crucially, the magnitude of these effects varied in spa
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Journal articleQiao S, Harrison SP, Prentice IC, et al., 2023,
Optimality-based modelling of wheat sowing dates globally
, Agricultural Systems, Vol: 206, Pages: 1-11, ISSN: 0308-521XCONTEXTSowing dates are currently an essential input for crop models. However, in the future, the optimal sowing time will be affected by climate changes and human adaptations to these changes. A better understanding of what determines the choice of wheat type and sowing dates is required to be able to predict future crop yields reliably.OBJECTIVEThis study was conducted to understand how climate conditions affect the choice of wheat types and sowing dates globally.METHODSWe develop a model integrating optimality concepts for simulating gross primary production (GPP) with climate constraints on wheat phenology to predict sowing dates. We assume that wheat could be sown at any time with suitable climate conditions and farmers would select a sowing date that maximises yields. The model is run starting on every possible climatically suitable day, determined by climate constraints associated with low temperature and intense precipitation. The optimal sowing date is the day which gives the highest yield in each location. We evaluate the simulated optimal sowing dates with data on observed sowing dates created by merging census-based datasets and local agronomic information, then predict their changes under future climate scenarios to gain insight into the impacts of climate change.RESULTS AND CONCLUSIONSCold-season temperatures are the major determinant of sowing dates in the extra-tropics, whereas the seasonal cycle of monsoon rainfall is important in the tropics. Our model captures the timing of reported sowing dates, with differences of less than one month over much of the world; maximum errors of up to two months occur in tropical regions with large altitudinal gradients. Discrepancies between predictions and observations are larger in tropical regions than temperate and cold regions. Slight warming is shown to promote earlier sowing in wet areas but later in dry areas; larger warming leads to delayed sowing in most regions. These predictions arise due to the interac
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Journal articleIsbell F, Balvanera P, Mori AS, et al., 2023,
Expert perspectives on global biodiversity loss and its drivers and impacts on people
, FRONTIERS IN ECOLOGY AND THE ENVIRONMENT, Vol: 21, Pages: 94-103, ISSN: 1540-9295- Author Web Link
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- Citations: 19
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Journal articleValdez JWW, Callaghan CTT, Junker J, et al., 2023,
The undetectability of global biodiversity trends using local species richness
, ECOGRAPHY, Vol: 2023, ISSN: 0906-7590- Author Web Link
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- Citations: 5
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Journal articleGumbs R, Gray C, Böhm M, et al., 2023,
The EDGE2 protocol: advancing the prioritisation of Evolutionarily Distinct and Globally Endangered species for practical conservation action
, PLoS Biology, Vol: 21, Pages: 1-22, ISSN: 1544-9173The conservation of evolutionary history has been linked to increased benefits for humanity and can be captured by phylogenetic diversity (PD). The Evolutionarily Distinct and Globally Endangered (EDGE) metric has, since 2007, been used to prioritise threatened species for practical conservation that embody large amounts of evolutionary history. While there have been important research advances since 2007, they have not been adopted in practice because of a lack of consensus in the conservation community. Here, building from an interdisciplinary workshop to update the existing EDGE approach, we present an “EDGE2” protocol that draws on a decade of research and innovation to develop an improved, consistent methodology for prioritising species conservation efforts. Key advances include methods for dealing with uncertainty and accounting for the extinction risk of closely related species. We describe EDGE2 in terms of distinct components to facilitate future revisions to its constituent parts without needing to reconsider the whole. We illustrate EDGE2 by applying it to the world’s mammals. As we approach a crossroads for global biodiversity policy, this Consensus View shows how collaboration between academic and applied conservation biologists can guide effective and practical priority-setting to conserve biodiversity.
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Journal articleGermain RR, Feng S, Buffan L, et al., 2023,
Changes in the functional diversity of modern bird species over the last million years.
, Proc Natl Acad Sci U S A, Vol: 120, Pages: e2201945119-e2201945119Despite evidence of declining biosphere integrity, we currently lack understanding of how the functional diversity associated with changes in abundance among ecological communities has varied over time and before widespread human disturbances. We combine morphological, ecological, and life-history trait data for >260 extant bird species with genomic-based estimates of changing effective population size (Ne) to quantify demographic-based shifts in avian functional diversity over the past million years and under pre-anthropogenic climate warming. We show that functional diversity was relatively stable over this period, but underwent significant changes in some key areas of trait space due to changing species abundances. Our results suggest that patterns of population decline over the Pleistocene have been concentrated in particular regions of trait space associated with extreme reproductive strategies and low dispersal ability, consistent with an overall erosion of functional diversity. Further, species most sensitive to climate warming occupied a relatively narrow region of functional space, indicating that the largest potential population increases and decreases under climate change will occur among species with relatively similar trait sets. Overall, our results identify fluctuations in functional space of extant species over evolutionary timescales and represent the demographic-based vulnerability of different regions of functional space among these taxa. The integration of paleodemographic dynamics with functional trait data enhances our ability to quantify losses of biosphere integrity before anthropogenic disturbances and attribute contemporary biodiversity loss to different drivers over time.
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Journal articlePawar S, 2023,
Another step towards a unifying theory for ecosystems?
, JOURNAL OF BIOSCIENCES, Vol: 48, ISSN: 0250-5991 -
Journal articleRansome E, Hobbs F, Jones S, et al., 2023,
Evaluating the transmission risk of SARS-CoV-2 from sewage pollution
, Science of the Total Environment, Vol: 858, Pages: 1-8, ISSN: 0048-9697The presence of SARS-CoV-2 in untreated sewage has been confirmed in many countries but its incidence and infection risk in contaminated waters is poorly understood. The River Thames in the UK receives untreated sewage from 57 Combined Sewer Overflows (CSOs), with many discharging dozens of times per year. This study investigated if such discharges provide a pathway for environmental transmission of SARS-CoV-2. Samples of wastewater, surface water, and sediment collected close to six CSOs on the River Thames were assayed over eight months for SARS-CoV-2 RNA and infectious virus. Bivalves were also sampled as an indicator species of viral bioaccumulation. Sediment and water samples from the Danube and Sava rivers in Serbia, where raw sewage is also discharged in high volumes, were assayed as a positive control. No evidence of SARS-CoV-2 RNA or infectious virus was found in UK samples, in contrast to RNA positive samples from Serbia. Furthermore, this study shows that infectious SARS-CoV-2 inoculum is stable in Thames water and sediment for <3 days, while SARS-CoV-2 RNA is detectable for at least seven days. This indicates that dilution of wastewater likely limits environmental transmission, and that detection of viral RNA alone is not an indication of pathogen spillover.
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Journal articleArce A, Cantwell-Jones A, Tansley M, et al., 2023,
Signatures of increasing environmental stress in bumblebee wings over the past century: Insights from museum specimens
, Journal of Animal Ecology, Vol: 92, Pages: 297-309, ISSN: 0021-87901. Determining when animal populations have experienced stress in the past is fundamental to understanding how risk factors drive contemporary and future species’ responses to environmental change. For insects, quantifying stress and associating it with environmental factors has been challenging due to a paucity of time-series data and because detectable population-level responses can show varying lag effects. One solution is to leverage historic entomological specimens to detect morphological proxies of stress experienced at the time stressors emerged, allowing us to more accurately determine population responses.2. Here we studied specimens of four bumblebee species, an invaluable group of insect pollinators, from five museums collected across Britain over the 20th century. We calculated the degree of fluctuating asymmetry (FA; random deviations from bilateral symmetry) between the right and left forewings as a potential proxy of developmental stress.3. We: i) investigated whether baseline FA levels vary between species, and how this compares between the first and second half of the century; ii) determined the extent of FA change over the century in the four bumblebee species, and whether this followed a linear or non-linear trend; iii) tested which annual climatic conditions correlated with increased FA in bumblebees.4. Species differed in their baseline FA, with FA being higher in the two species that have recently expanded their ranges in Britain. Overall, FA significantly increased over the century but followed a non-linear trend, with the increase starting c. 1925. We found relatively warm and wet years were associated with higher FA. 5. Collectively our findings show that FA in bumblebees increased over the 20th century and under weather conditions that will likely increase in frequency with climate change. By plotting FA trends and quantifying the contribution of annual climate conditions on past populations, we provide an important step towards impro
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Journal articleMullin VE, Stephen W, Arce AN, et al., 2023,
First large-scale quantification study of DNA preservation in insects from natural history collections using genome-wide sequencing
, Methods in Ecology and Evolution, Vol: 14, Pages: 360-371, ISSN: 2041-210X1. Insect declines are a global issue with significant ecological and economic ramifications. Yet we have a poor understanding of the genomic impact these losses can have. Genome-wide data from historical specimens has the potential to provide baselines of population genetic measures to study population change, with natural history collections representing large repositories of such specimens. However, an initial challenge in conducting historical DNA data analyses, is to understand how molecular preservation varies between specimens.2. Here, we highlight how Next Generation Sequencing methods developed for studying archaeological samples can be applied to determine DNA preservation from only a single leg taken from entomological museum specimens, some of which are more than a century old. An analysis of genome-wide data from a set of 113 red-tailed bumblebee (Bombus lapidarius) specimens, from five British museum collections, was used to quantify DNA preservation over time. Additionally, to improve our analysis and further enable future research we generated a novel assembly of the red-tailed bumblebee genome. 3. Our approach shows that museum entomological specimens are comprised of short DNA fragments with mean lengths below 100 base pairs (BP), suggesting a rapid and large-scale post-mortem reduction in DNA fragment size. After this initial decline, however, we find a relatively consistent rate of DNA decay in our dataset, and estimate a mean reduction in fragment length of 1.9bp per decade. The proportion of quality filtered reads mapping to our assembled reference genome was around 50%, and decreased by 1.1 % per decade. 4. We demonstrate that historical insects have significant potential to act as sources of DNA to create valuable genetic baselines. The relatively consistent rate of DNA degradation, both across collections and through time, mean that population level analyses - for example for conservation or evolutionary studies - are entirely feasible, a
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Journal articleBrazeau MDD, Yuan H, Giles S, et al., 2023,
A well-preserved 'placoderm' (stem-group Gnathostomata) upper jaw from the Early Devonian of Mongolia clarifies jaw evolution
, Royal Society Open Science, Vol: 10, ISSN: 2054-5703The origin of jaws and teeth remains contentious in vertebrate evolution. ‘Placoderms’ (Silurian-Devonian armoured jawed fishes) are central to debates on the origins of these anatomical structures. ‘Acanthothoracids’ are generally considered the most primitive ‘placoderms’. However, they are so far known mainly from disarticulated skeletal elements that are typically incomplete. The structure of the jaws—particularly the jaw hinge—is poorly known, leaving open questions about their jaw function and comparison with other placoderms and modern gnathostomes. Here we describe a near-complete ‘acanthothoracid’ upper jaw, allowing us to reconstruct the likely orientation and angle of the bite and compare its morphology with that of other known ‘placoderm’ groups. We clarify that the bite position is located on the upper jaw cartilage rather than on the dermal cheek and thus show that there is a highly conserved bite morphology among most groups of ‘placoderms’, regardless of their overall cranial geometry. Incorporation of the dermal skeleton appears to provide a sound biomechanical basis for jaw origins. It appears that ‘acanthothoracid’ dentitions were fundamentally similar in location to that of arthrodire ‘placoderms’, rather than resembling bony fishes. Irrespective of current phylogenetic uncertainty, the new data here resolve the likely general condition for ‘placoderms’ as a whole, and as such, ancestral morphology of known jawed vertebrates.
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Journal articleBloomfield KJ, Stocker BD, Keenan TF, et al., 2023,
Environmental controls on the light use efficiency of terrestrial gross primary production
, Global Change Biology, Vol: 29, Pages: 1037-1053, ISSN: 1354-1013Gross primary production (GPP) by terrestrial ecosystems is a key quantity in the global carbon cycle. The instantaneous controls of leaf-level photosynthesis are well established, but there is still no consensus on the mechanisms by which canopy-level GPP depends on spatial and temporal variation in the environment. The standard model of photosynthesis provides a robust mechanistic representation for C3 species; however, additional assumptions are required to “scale up” from leaf to canopy. As a consequence, competing models make inconsistent predictions about how GPP will respond to continuing environmental change. This problem is addressed here by means of an empirical analysis of the light use efficiency (LUE) of GPP inferred from eddy covariance carbon dioxide flux measurements, in situ measurements of photosynthetically active radiation (PAR), and remotely sensed estimates of the fraction of PAR (fAPAR) absorbed by the vegetation canopy. Focusing on LUE allows potential drivers of GPP to be separated from its overriding dependence on light. GPP data from over 100 sites, collated over 20 years and located in a range of biomes and climate zones, were extracted from the FLUXNET2015 database and combined with remotely sensed fAPAR data to estimate daily LUE. Daytime air temperature, vapor pressure deficit, diffuse fraction of solar radiation, and soil moisture were shown to be salient predictors of LUE in a generalized linear mixed-effects model. The same model design was fitted to site-based LUE estimates generated by 16 terrestrial ecosystem models. The published models showed wide variation in the shape, the strength, and even the sign of the environmental effects on modeled LUE. These findings highlight important model deficiencies and suggest a need to progress beyond simple “goodness of fit” comparisons of inferred and predicted carbon fluxes toward an approach focused on the functional responses of the underlying dependencies.
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Journal articleGarcia FC, Clegg T, O'Neill DB, et al., 2023,
The temperature dependence of microbial community respiration is amplified by changes in species interactions
, NATURE MICROBIOLOGY, Vol: 8, Pages: 272-283, ISSN: 2058-5276- Author Web Link
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- Citations: 3
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Journal articleWesterband AC, Wright IJ, Maire V, et al., 2023,
Coordination of photosynthetic traits across soil and climate gradients
, Global Change Biology, Vol: 29, Pages: 856-873, ISSN: 1354-1013"Least-cost theory" posits that C3 plants should balance rates of photosynthetic water loss and carboxylation in relation to the relative acquisition and maintenance costs of resources required for these activities. Here we investigated the dependency of photosynthetic traits on climate and soil properties using a new Australia-wide trait dataset spanning 528 species from 67 sites. We tested the hypotheses that plants on relatively cold or dry sites, or on relatively more fertile sites, would typically operate at greater CO2 drawdown (lower ratio of leaf internal to ambient CO2 , Ci :Ca ) during light-saturated photosynthesis, and at higher leaf N per area (Narea ) and higher carboxylation capacity (Vcmax 25 ) for a given rate of stomatal conductance to water vapour, gsw . These results would be indicative of plants having relatively higher water costs than nutrient costs. In general, our hypotheses were supported. Soil total phosphorus (P) concentration and (more weakly) soil pH exerted positive effects on the Narea -gsw and Vcmax 25 -gsw slopes, and negative effects on Ci :Ca . The P effect strengthened when the effect of climate was removed via partial regression. We observed similar trends with increasing soil cation exchange capacity and clay content, which affect soil nutrient availability, and found that soil properties explained similar amounts of variation in the focal traits as climate did. Although climate typically explained more trait variation than soil did, together they explained up to 52% of variation in the slope relationships and soil properties explained up to 30% of the variation in individual traits. Soils influenced photosynthetic traits as well as their coordination. In particular, the influence of soil P likely reflects the Australia's geologically ancient low-relief landscapes with highly leached soils. Least-cost theory provides a valuable framework for understanding trade-offs between resource costs and use in plants, including
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Journal articleQureshi A, Keen E, Brown G, et al., 2023,
The size of larval rearing container modulates the effects of diet amount and larval density on larval development in Aedes aegypti
, PLoS One, Vol: 18, Pages: 1-18, ISSN: 1932-6203Mass-rearing of mosquitoes under laboratory conditions is an important part of several new control techniques that rely on the release of males to control mosquito populations. While previous work has investigated the effect of larval density and diet amount on colony productivity, the role of the size of the container in which larval development takes place has been relatively ignored. We investigated the role of container size in shaping life history and how this varied with density and food availability in Aedes aegypti, an important disease vector and target of mass-rearing operations. For each treatment combination, immature development time and survival and adult body size and fecundity were measured, and then combined into a measure of productivity. We additionally investigated how larval aggregation behaviour varied with container size. Container size had important effects on life history traits and overall productivity. In particular, increasing container size intensified density and diet effects on immature development time. Productivity was also impacted by container size when larvae were reared at high densities (1.4 larva/ml). In these treatments, the productivity metric of large containers was estimated to be significantly lower than medium or small containers. Regardless of container size, larvae were more likely to be observed at the outer edges of containers, even when this led to extremely high localized densities. We discuss how container size and larval aggregation responses may alter the balance of energy input and output to shape development and productivity.
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