Single-species Studies Research Articles

Understanding author choices in the current conservation publishing landscape.

Conservation literature addresses a broad spectrum of interdisciplinary questions and benefits. Conservation science benefits most when a diverse range of authors are represented, particularly those from countries where much conservation work is focused. In other disciplines, it is well known that barriers and biases exist in the academic publishing sphere, which can affect research dissemination and an author's career development. We used a discrete choice experiment to determine how 7 journal attributes affect authors' choices of where to publish in conservation. We targeted authors directly by contacting authors published in 18 target journals and indirectly via communication channels for conservation organizations. We only included respondents who had previously published in a conservation-related journal. We used a multinomial logit model and a latent class model to investigate preferences for all respondents and distinct subpopulations. We identified 3 demographic groups across 1038 respondents (older authors from predominantly middle-income countries, younger authors from predominantly middle-income countries, and younger authors from high-income countries) who had published in conservation journals. Each group exhibited different publishing preferences. Only 2 attributes showed a consistent response across groups: cost to publish negatively affected journal choice, including authors in high-income countries, and authors had a consistent preference for double-blind review. Authors from middle-income countries were willing to pay more for society-owned journals, unlike authors from high-income countries. Journals with a broad geographical scope that were open access and that had relatively high impact factors were preferred by 2 of the 3 demographic groups. However, journal scope and open access were more important in dictating journal choice than impact factor. Overall, different demographics had different preferences for journals and were limited in their selection based on attributes such as open access policy. However, the scarcity of respondents from low-income countries (2% of respondents) highlights the pervasive barriers to representation in conservation research. We recommend journals offer double-blind review, reduce or remove open access fees, investigate options for free editorial support, and better acknowledge the value of local-scale single-species studies. Academic societies in particular must reflect on how their journals support conservation and conservation professionals.

An assemblage-level comparison of genetic diversity and population genetic structure between island and mainland ant populations.

Island biotas provide unparalleled opportunities to examine evolutionary processes. Founder effects and bottlenecks, e.g., typically decrease genetic diversity in island populations, while selection for reduced dispersal can increase population structure. Given that support for these generalities mostly comes from single-species analyses, assemblage-level comparisons are needed to clarify how (i) colonization affects the gene pools of interacting insular organisms, and (ii) patterns of genetic differentiation vary within assemblages of organisms. Here, we use genome-wide sequence data from ultraconserved elements (UCEs) to compare the genetic diversity and population structure of mainland and island populations of nine ant species in coastal southern California. As expected, island populations (from Santa Cruz Island) had lower expected heterozygosity and Watterson's theta compared to mainland populations (from the Lompoc Valley). Island populations, however, exhibited smaller genetic distances among samples, indicating less population subdivision. Within the focal assemblage, pairwise Fst values revealed pronounced interspecific variation in mainland-island differentiation, which increases with gyne body size. Our results reveal population differences across an assemblage of interacting species and illuminate general patterns of insularization in ants. Compared to single-species studies, our analysis of nine conspecific population pairs from the same island-mainland system offers a powerful approach to studying fundamental evolutionary processes.

Insights from 20 years of mammal population research in Indonesia

Abstract Mammal populations are declining in biodiverse tropical regions. Global analyses have identified Indonesia as a hotspot of vertebrate decline, although relatively few data are available to substantiate these claims. We reviewed research articles published during 2000–2020 on 104 medium-sized to large terrestrial mammal species found in Indonesia to help inform conservation management and future research. We identified 308 peer-reviewed studies published in English or Bahasa Indonesia, with an increase in publication rate (articles published per year) over time. Studies of species distributions dominated the literature, followed by publications on abundance, species diversity and combinations of these topics. Most publications concerned single-species studies conducted at a single location and a single point in time. We identify four key issues that should be addressed by future research and conservation efforts: (1) disproportionate focus on a small number of species; (2) geographical bias towards west Indonesia (Sumatra, Kalimantan and Java–Bali), with few published studies from central (Sulawesi, Nusa Tenggara and Maluku) and east (Papua) Indonesia; (3) limitations to survey design, sampling effort and data analysis; and (4) lack of long-term wildlife population studies. We also note challenges local researchers face in publishing their studies in international journals because of language barriers and costs. Greater use of existing biodiversity data and continued capacity building for local researchers, particularly those in central and east Indonesia, are critical to effectively guide future wildlife monitoring and improve the conservation status of Indonesian mammals.

Unraveling the complexities of Cd-aniline composite pollution: Insights from standalone and joint toxicity assessments in a bacterial community

Cadmium (Cd) and aniline frequently co-occur in industrial settings but have rarely been addressed as composite toxicants in terms of the overall toxicity despite extensive knowledge of the environmental impact of each individual pollutant. In this study, we attempt to assess the relation of individual and combined toxic effects of Cd and aniline using a bacterial consortium cultured from soils as a model system. Results showed that the consortial bacteria exhibited drastically stronger tolerance to stand-alone Cd and aniline in comparison to literature data acquired from single species studies. When occurring simultaneously, the joint toxicity displayed a concentration-dependent behavior that wasn't anticipated based on individual chemical tests. Specifically, additive effects manifested with Cd and aniline at their IC10s, but changed to synergistic when the concentrations increased to IC20, and finally transitioned into antagonistic at IC30s and beyond. In addition, co-occurring aniline appeared to have retarded the cellular accumulation of Cd while increasing the enzymatic activities of superoxide dismutase and catalase relative to that in Cd-alone treatments. Finally, the bacterial community experienced distinct compositional changes under solo and combined toxicities with several genera exhibiting inconsistent behavior between treatments of single and composite toxicants. Findings from this study highlight the complexity of bacterial response to composite pollutions and point to the need for more comprehensive references in risk and toxicology assessment at multi-chemical contamination sites.

Two common, often coexisting grassland plant species differ in their evolutionary potential in response to experimental drought.

For terrestrial plant communities, the increase in frequency and intensity of drought events is considered as one of the most severe consequences of climate change. While single-species studies demonstrate that drought can lead to relatively rapid adaptive genetic changes, the evolutionary potential and constraints to selection need to be assessed in comparative approaches to draw more general conclusions. In a greenhouse experiment, we compare the phenotypic response and evolutionary potential of two co-occurring grassland plant species, Bromus erectus and Trifolium pratense, in two environments differing in water availability. We quantified variation in functional traits and reproductive fitness in response to drought and compared multivariate genetic variance-covariance matrices and predicted evolutionary responses between species. Species showed different drought adaptation strategies, reflected in both their species-specific phenotypic plasticity and predicted responses to selection indicating contrasting evolutionary potential under drought. In T. pratense we found evidence for stronger genetic constraints under drought compared to more favourable conditions, and for some traits plastic and predicted evolutionary responses to drought had opposing directions, likely limiting the potential for adaptive change. Our study contributes to a more detailed understanding of the evolutionary potential of species with different adaptive strategies in response to climate change and may help to inform future scenarios for semi-natural grassland ecosystems.

Meta-Analysis of the Effect of Nitric Oxide Application on Heavy Metal Stress Tolerance in Plants

Substantial single-species studies have reported the facility of nitric oxide (NO) in alleviating heavy metal-induced stress in plants. Understanding the mechanisms of NO-involved stress alleviation is progressing; however, a quantitative description of the alleviative capacity of NO against heavy metal stress is still lacking. We combined the results of 86 studies using meta-analysis to statistically assess the responses of heavy metal-stressed plants to NO supply across several metal stresses and plant families. The results showed that plant biomass was consistently improved following NO supply to metal-stressed plants. NO played an important role in mitigating oxidative damage caused by heavy metal stress by significantly stimulating the activities of antioxidant enzymes. Moreover, NO supply consistently increased the Ca, Fe, and Mg contents in both leaves and roots. Plant tissues accumulated less heavy metals when exposed to heavy metal stress after NO addition. Additionally, the best concentration of SNP (an NO donor) for hydroponic culture is in the range of 75-150 μM. We further confirmed that NO application can generally alleviate plant heavy metal stress and its action pathway. The results presented here can help guide future applications of NO as a plant growth regulator in agriculture and breeding plants for heavy metal stress tolerance.

The distribution of the Lansing Effect across animal species.

Maternal senescence is the reduction in individual performance associated with increased maternal age at conception. When manifested on adult lifespan, this phenomenon is known as the 'Lansing Effect'. Single-species studies report both maternal age-related increases and decreases in adult lifespan, but no comprehensive review of the literature has yet been undertaken to determine if the Lansing Effect is a widespread phenomenon. To address this knowledge gap, we performed a meta-analysis of maternal aging rates taken from all available published studies. We recovered 78 estimates from 22 studies representing 15 species. All studies taken together suggest a propensity for a Lansing Effect, with an estimated average effect of maternal age on offspring adult lifespan of between -17% to -22%, depending upon our specific choice of model. We failed to find a significant effect of animal class or insect order but given the oversampling of insect species in the published literature and the paucity of vertebrate studies, we infer that only rotifers and insects yet demonstrate a tendency towards expressing the phenomenon.

Threats and benefits of invasive alien plant species on pollinators

Invasive alien plant species are usually disliked due to their high pressure on native communities. However, their ecological effects on pollinators are complex: some species provide abundant floral resources, boosting the number of pollinators, while they often disrupt plant-pollinator interactions by outcompeting native plants. Our direct knowledge is mainly based on single-species studies, while understanding the mechanism of these complex ecological interactions needs multi-species field-based approaches. It is also imperative to clarify the pros and cons of invasive plants and drivers of invasion from the perspective of pollinators. We conducted a standard protocol-driven regional study in Central and Eastern Europe, comparing 6-7 invaded and non-invaded sites of 12 herbaceous invasive plant species. We sampled floral resources, bees, and hoverflies before and during the flowering of the invasive plants. We analysed the effects of plant invasion at the invasive plant species level and in combined analyses, and tested whether the life span (perennial vs. annual) and flowering time (early-, middle-, and late-flowering) of invasive plants affect the abundance, species richness, diversity and species composition of native plants and pollinators. The combined analyses showed lower abundance and species richness of flowering plants and pollinators before, and higher abundance of both during the flowering of invasive plants in invaded sites. However, invasive plants had significant species-specific effects. Perennial invasive plants had a stronger negative impact on floral resources and pollinators already before their flowering compared to annuals. Flowering time of invasive plants affected the pollinator guilds differently. We suggest that in certain critical time periods of the year, invasive plants might provide the dominant foraging resources for pollinators in an invaded ecosystem. But, they also often cause significant losses in native floral resources over the year. Instead of simple eradication, careful preparation and consideration might be needed during removal of invasive plants.

Potentially misleading phylogenetic signal and its explanation in single species studies – contrasting Loeskypnum badium, Sarmentypnum exannulatum and Warnstorfia fluitans

Incongruence among morphological and different molecular data sets can be troublesome for species and genus circumscriptions and may cause problems in interpreting intraspecific relationships. Based on the nuclear ITS1 and 2, and the plastid rpl16, trnG and trnL-trnF, it is shown that while such incongruence is not detected if the individual species Loeskypnum badium, Sarmentypnum exannulatum or Warnstorfia fluitans are studied, it may be striking when analyzed in a wider context within the Calliergonaceae. The wider context did not affect the interpretation of internal relationships within L. badium, but many specimens of the other two species were suggested to belong to different species by either marker set. For a large minority of S. exannulatum (8% of specimens), ITS suggested W. fluitans and for 28% of W. fluitans the plastid markers suggested S. exannulatum or (one case) S. sarmentosum. The found pattern agrees with a scenario where archegonia of female plants of S. exannulatum or S. sarmentosum were fertilized by W. fluitans spermatozoids. The produced spores all have the maternally inherited Sarmentypnum plastids, but nuclear genome portions from either the involved Sarmentypnum species or W. fluitans. If foreign plastids affect the functionality of plants less than foreign nuclear portions in plants with mixed genomes, morphological W. fluitans plants with Sarmentypnum plastids should survive to a higher degree than vice versa.

Application of a mobile laboratory using a selected-ion flow-tube mass spectrometer (SIFT-MS) for characterisation of volatile organic compounds and atmospheric trace gases

Abstract. Over the last 2 decades, the importance of emissions source types of atmospheric pollutants in urban areas has undergone significant change. In particular, there has been a considerable reduction in emissions associated with road vehicles. Understanding the role played by different source sectors is important if effective air pollution control is to be achieved. Current atmospheric measurements are made at fixed monitoring sites, most of which do not include the measurement of volatile organic compounds (VOCs), so our understanding of the temporal and spatial variation of pollutants is limited. Here we describe the application of a mobile laboratory using a selected-ion flow-tube mass spectrometer (SIFT-MS) and other trace gas instrumentation to provide on-road, high-spatial- and temporal-resolution measurements of CO2, CH4, VOCs and other trace gases. We then illustrate the potential of this platform for developing source characterisation methods that account for the similarity in correlation between species. Finally, we consider the benefits of high-spatial- and temporal-resolution measurements in characterising different types of sources, which would be difficult or impossible for single-species studies.

Another Decade of Marine Climate Change Experiments: Trends, Progress and Knowledge Gaps

Anthropogenic climate change is a significant driver of change in marine ecosystems globally. To improve mechanistic understanding of the impact of climate-related stressors, experimental work on marine organisms has intensified in recent decades. A previous synthesis paper published nearly a decade ago established that Marine Climate Change Experiments (MCCEs) published from 2000–2009 were primarily laboratory-based and focused on single stressors and individual focal temperate species. Using consistent methodology, we compared the 2000–2009 analysis to experiments published in the following decade (i.e. 2010–2019) to assess recent trends in MCCEs and to determine to what extent knowledge gaps and research priorities have been addressed. The search returned 854 papers, vs. 110 from the 2000s, indicating considerable intensification of research effort and output. We found again that single species studies were most common, particularly with benthic invertebrates as model organisms, and that laboratory-based research comprised over 90% of all studies. However, multiple stressor experiments increased substantially, where tests for interaction effects between ocean acidification (i.e., increased pCO2) and warming were particularly common. Furthermore, a wider range of model species were studied and more community-level experiments were conducted in the 2010s compared with the 2000s. In addition, studies on behavioral responses, transgenerational effects, genetic adaptation and extreme climatic events increased markedly. These recent advances in MCCEs have undoubtedly improved understanding of how climate change will affect marine organisms and the communities and ecosystems they underpin. Going forward, biases in the type and distribution of model organisms should be addressed to enhance general understanding of responses to environmental change. Similarly, experiments should manipulate a greater number and range of climate and non-climate factors and increase the number of target organisms to increase realism. Finally, where possible, further research should be combined and contextualized with field-based experiments and observations to better reflect the complexity of marine ecosystems and yield more representative responses to ocean climate change.

Sensitivity to habitat fragmentation across European landscapes in three temperate forest herbs

ContextEvidence for effects of habitat loss and fragmentation on the viability of temperate forest herb populations in agricultural landscapes is so far based on population genetic studies of single species in single landscapes. However, forest herbs differ in their life histories, and landscapes have different environments, structures and histories, making generalizations difficult.ObjectivesWe compare the response of three slow-colonizing forest herbs to habitat loss and fragmentation and set this in relation to differences in life-history traits, in particular their mating system and associated pollinators.MethodsWe analysed the herbs’ landscape-scale population genetic structure based on microsatellite markers from replicate forest fragments across seven European agricultural landscapes.ResultsAll species responded to reductions in population size with a decrease in allelic richness and an increase in genetic differentiation among populations. Genetic differentiation also increased with enhanced spatial isolation. In addition, each species showed unique responses. Heterozygosity in the self-compatible Oxalis acetosella was reduced in smaller populations. The genetic diversity of Anemone nemorosa, whose main pollinators are less mobile, decreased with increasing spatial isolation, but not that of the bumblebee-pollinated Polygonatum multiflorum.ConclusionsOur study indicates that habitat loss and fragmentation compromise the long-term viability of slow-colonizing forest herbs despite their ability to persist for many decades by clonal propagation. The distinct responses of the three species studied within the same landscapes confirm the need of multi-species approaches. The mobility of associated pollinators should be considered an important determinant of forest herbs’ sensitivity to habitat loss and fragmentation.

Evaluating Coexistence of Fish Species with Coastal Cutthroat Trout in Low Order Streams of Western Oregon and Washington, USA

When multiple species of fish coexist there are a host of potential ways through which they may interact, yet there is often a strong focus on studies of single species without considering these interactions. For example, many studies of forestry–stream interactions in the Pacific Northwest have focused solely on the most prevalent species: Coastal cutthroat trout. To examine the potential for interactions of other fishes with coastal cutthroat trout, we conducted an analysis of 281 sites in low order streams located on Washington’s Olympic Peninsula and along the central Oregon coast. Coastal cutthroat trout and juvenile coho salmon were the most commonly found salmonid species within these streams and exhibited positive associations with each other for both presence and density. Steelhead were negatively associated with the presence of coastal cutthroat trout as well as with coho salmon and sculpins (Cottidae). Coastal cutthroat trout most frequently shared streams with juvenile coho salmon. For densities of these co-occurring species, associations between these two species were relatively weak compared to the strong influences of physical stream conditions (size and gradient), suggesting that physical conditions may have more of an influence on density than species interactions. Collectively, our analysis, along with a review of findings from prior field and laboratory studies, suggests that the net effect of interactions between coastal cutthroat trout and coho salmon do not appear to inhibit their presence or densities in small streams along the Pacific Northwest.

Relationship between total plasma homocysteine and the risk of aneurysms - a meta-analysis.

Our meta-analysis focused on the relationship between homocysteine (Hcy) level and the incidence of aneurysms and looked at the relationship between smoking, hypertension and aneurysms. A systematic literature search of Pubmed, Web of Science, and Embase databases (up to March 31, 2020) resulted in the identification of 19 studies, including 2,629 aneurysm patients and 6,497 healthy participants. Combined analysis of the included studies showed that number of smoking, hypertension and hyperhomocysteinemia (HHcy) in aneurysm patients was higher than that in the control groups, and the total plasma Hcy level in aneurysm patients was also higher. These findings suggest that smoking, hypertension and HHcy may be risk factors for the development and progression of aneurysms. Although the heterogeneity of meta-analysis was significant, it was found that the heterogeneity might come from the difference between race and disease species through subgroup analysis. Large-scale randomized controlled studies of single species and single disease species are needed in the future to supplement the accuracy of the results.

The Best-Practice Organism for Single-Species Studies of Antimicrobial Efficacy against Biofilms Is Pseudomonas aeruginosa.

As potable water scarcity increases across the globe; it is imperative to identify energy and cost-effective processes for producing drinking-water from non-traditional sources. One established method is desalination of brackish and seawater via reverse osmosis (RO). However, the buildup of microorganisms at the water-membrane interface, known as biofouling, clogs RO membranes over time, increasing energy requirements and cost. To investigate biofouling mitigation methods, studies tend to focus on single-species biofilms; choice of organism is crucial to producing useful results. To determine a best-practice organism for studying antimicrobial treatment of biofilms, with specific interest in biofouling of RO membranes, we answered the following two questions, each via its own semi-systematic review: 1. Which organisms are commonly used to test antimicrobial efficacy against biofilms on RO membranes? 2. Which organisms are commonly identified via genetic analysis in biofilms on RO membranes? We then critically review the results of two semi-systematic reviews to identify pioneer organisms from the listed species. We focus on pioneer organisms because they initiate biofilm formation, therefore, inhibiting these organisms specifically may limit biofilm formation in the first place. Based on the analysis of the results, we recommend utilizing Pseudomonas aeruginosa for future single-species studies focused on biofilm treatment including, but not limited to, biofouling of RO membranes.

Large-scale discovery of male reproductive tract-specific genes through analysis of RNA-seq datasets

BackgroundThe development of a safe, effective, reversible, non-hormonal contraceptive method for men has been an ongoing effort for the past few decades. However, despite significant progress on elucidating the function of key proteins involved in reproduction, understanding male reproductive physiology is limited by incomplete information on the genes expressed in reproductive tissues, and no contraceptive targets have so far reached clinical trials. To advance product development, further identification of novel reproductive tract-specific genes leading to potentially druggable protein targets is imperative.ResultsIn this study, we expand on previous single tissue, single species studies by integrating analysis of publicly available human and mouse RNA-seq datasets whose initial published purpose was not focused on identifying male reproductive tract-specific targets. We also incorporate analysis of additional newly acquired human and mouse testis and epididymis samples to increase the number of targets identified. We detected a combined total of 1178 genes for which no previous evidence of male reproductive tract-specific expression was annotated, many of which are potentially druggable targets. Through RT-PCR, we confirmed the reproductive tract-specific expression of 51 novel orthologous human and mouse genes without a reported mouse model. Of these, we ablated four epididymis-specific genes (Spint3, Spint4, Spint5, and Ces5a) and two testis-specific genes (Pp2d1 and Saxo1) in individual or double knockout mice generated through the CRISPR/Cas9 system. Our results validate a functional requirement for Spint4/5 and Ces5a in male mouse fertility, while demonstrating that Spint3, Pp2d1, and Saxo1 are each individually dispensable for male mouse fertility.ConclusionsOur work provides a plethora of novel testis- and epididymis-specific genes and elucidates the functional requirement of several of these genes, which is essential towards understanding the etiology of male infertility and the development of male contraceptives.

Functional traits in macrophyte studies: Current trends and future research agenda

• A growing interest is turned to the functional traits of macrophytes. • Studies on macrophyte traits have so far overlooked important biodiversity hotspots. • The study of invasive species has been mainly limited to few traits and subjects. • Root traits may explain important plant functions and need further research. • The use of remote sensing may help understanding plant functions at multiple scales. The use of functional traits (FTs) can provide quantitative information to explain macrophyte ecology more effectively than traditional taxonomic-based methods. This research aims to elucidate the trait-based approaches used in recent macrophyte studies to outline their applications, shortcomings, and future challenges. A systematic literature review focused on macrophytes and FTs was carried out on Scopus database (last accessed May 2020). The latest 520 papers published from 2010 to 2020, which represent 70 % of the whole literature selected since 1969, were carefully screened. Reviewed studies mainly investigated: 1) the role of FTs in shaping communities; 2) the responses of macrophytes to environmental gradients; 3) the application of FTs in monitoring anthropic pressures; and 4) the reasons for success of invasive species. Studied areas were concentrated in Europe (41 %) and Asia (32 %), overlooking other important biodiversity hotspots, and only 6.2 % of the world macrophytes species were investigated in dedicated single species studies. The FTs most commonly used include leaf economic and morphological traits, and we noticed a lack of attention on root traits and in general on spatial traits patterns, as well as a relatively poor understanding of how FTs mediate biotic interactions. High-throughput techniques, such as remote sensing, allow to map fine-scale variability of selected traits within and across systems, helping to clarify multiple links of FTs with ecological drivers and processes. We advise to promote investigations on root traits, and to push forward the integration of multiple approaches to better clarify the role of macrophytes at multiple scales.

Using Spectral Indices to Estimate Water Content and GPP inSphagnumMoss and Other Peatland Vegetation

Peatlands provide important ecosystem services including carbon storage and biodiversity conservation. Remote sensing shows potential for monitoring peatlands, but most off-the-shelf data products are developed for unsaturated environments and it is unclear how well they can perform in peatland ecosystems. Sphagnum moss is an important peatland genus with specific characteristics which can affect spectral reflectance, and we hypothesized that the prevalence of Sphagnum in a peatland could affect the spectral signature of the area. This article combines results from both laboratory and field experiments to assess the relationship between spectral indices and the moisture content and gross primary productivity (GPP) of peatland (blanket bog) vegetation species. The aim was to consider how well the selected indices perform under a range of conditions, and whether Sphagnum has a significant impact on the relationships tested. We found that both water indices tested [normalized difference water index (NDWI) and floating water band index (fWBI)] were sensitive to the water content changes in Sphagnum moss in the laboratory, and there was little difference between them. Most of the vegetation indices tested [the normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), structure insensitive pigment index (SIPI), and chlorophyll index (CIm)] were found to have a strong relationship with GPP both in the laboratory and in the field. The NDVI and EVI are useful for large-scale estimation of GPP, but are sensitive to the proportion of Sphagnum present. The CIm is less affected by different species proportions and might therefore be the best to use in areas where vegetation species cover is unknown. The photochemical reflectance index (PRI) is shown to be best suited to small-scale studies of single species.

Exploring ecosystem structure and function of the northern Kerguelen Plateau using a mass-balanced food web model

Annual phytoplankton blooms on the northern region of the Kerguelen Plateau fuel a productive food web that supports highly valuable commercial fisheries for Patagonian toothfish (Dissostichus eleginoides) and mackerel icefish (Champsocephalus gunnari). The food web on the plateau is understudied in comparison to other regions of the Southern Ocean. Major linkages and energy pathways have not been explored, and the combined effects of fishing and a changing climate on the ecosystem are largely unknown. Single species studies on the plateau have shown that the combined effects of climate change and fisheries are impacting populations, however, it is unclear how these impacts translate to the ecosystem. We extended an existing Ecopath model to describe food web dynamics on the plateau and investigate food web interactions with the fishery. Results from our model highlight, for the first time, the properties of the food web, major energy pathways and energy transfers between trophic levels. Energy transfer from detritus was most efficient at the lowest trophic level while energy from primary production was more efficient at higher trophic levels. Consumption and respiration were high in our system, most likely due to the inclusion of bacteria and microzooplankton. Killer whales, cephalopods and myctophids were key functional groups for energy transfer in the system. These groups were relatively data poor, suggesting a useful focus area for future updates to the model. Patagonian toothfish and mackerel icefish were heavily consumed in the food web, however, the inclusion of fisheries catches and by-catch had little to no impact on food web dynamics.

Pan-mammalian analysis of molecular constraints underlying extended lifespan

Although lifespan in mammals varies over 100-fold, the precise evolutionary mechanisms underlying variation in longevity remain unknown. Species-specific genetic changes have been observed in long-lived species including the naked mole-rat, bats, and the bowhead whale, but these adaptations do not generalize to other mammals. We present a novel method to identify associations between rates of protein evolution and continuous phenotypes across the entire mammalian phylogeny. Unlike previous analyses that focused on individual species, we treat absolute and relative longevity as quantitative traits and demonstrate that these lifespan traits affect the evolutionary constraint on hundreds of genes. Specifically, we find that genes related to cell cycle, DNA repair, cell death, the IGF1 pathway, and immunity are under increased evolutionary constraint in large and long-lived mammals. For mammals exceptionally long-lived for their body size, we find increased constraint in inflammation, DNA repair, and NFKB-related pathways. Strikingly, these pathways have considerable overlap with those that have been previously reported to have potentially adaptive changes in single-species studies, and thus would be expected to show decreased constraint in our analysis. This unexpected finding of increased constraint in many longevity-associated pathways underscores the power of our quantitative approach to detect patterns that generalize across the mammalian phylogeny.