SEARCH · bioRxiv Science

Results for “Ecology”

Search indexed bioRxiv preprints in genomics, neuroscience, cell biology and bioinformatics. Read source abstracts and check manuscript versions; preprints are not peer reviewed.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,279 records · Page 71Linked to original sources

bioRxiv2019

Estimating the abundance of duiker (Cephalophus spp.) populations in African rainforests: an overview of relevant methods

Duikers are among the most sought after antelope species for bush meat in central Africa. Estimates of population abundance of duikers based on reliable methods is therefore of prime importance for their sustainable management. Here we retrieved 31 studies from the literature and compared methods used to estimate the abundance of duiker populations in African rainforests. Implemented methods all derived from seven main combinations of sampling designs and population abundance estimators. We then evaluated the relevance of those seven methods by scoring them based on eight criteria selected according to their pros and cons reported in the litterature for large-scale population management of wildlife. For management purposes, methods derived from distance sampling offer the best compromise between the implementation costs and the biological information collected. In particular, both diurnal and nocturnal distance sampling can be recommended. Hunter calls and drive-netting are less reliable, but can be used in association with other measurements in the framework of indicators of ecological changes, a monitoring approach that has been successfully used in temperate ecosystems for managing large herbivores. Funding informationMinistere de lEnvironnement et du Developpement Durable de la Republique Democratique du Congo, Campus France and Centre National de la Recherche Scientifique (CNRS). ResumeLes cephalophes sont parmi les especes dantilopes les plus recherchees pour la viande de brousse en Afrique centrale. Lestimation de labondance des populations de cephalophes revet donc une importance primordiale pour leur gestion durable et adaptative. Nous avons extrait 31 etudes de la litterature et compare les methodes utilisees pour estimer labondance des populations de cephalophes dans les forets tropicales africaines. Les methodes employees derivent de sept combinaisons principales de plans dechantillonnage et destimateurs dabondance. Nous avons evalue la pertinence de ces sept methodes sur la base de criteres selectionnes en fonction de leurs avantages et inconvenients pour une gestion a grande echelle de la population. Les methodes derivees de lechantillonnage par distance offrent le meilleur compromis entre les couts de mise en uvre et les informations biologiques collectees. Les methodes dechantillonnage diurne et nocturne se sont montrees les plus satisfaisantes. Les methodes dappel par les chasseurs et de battue au filet sont moins fiables, mais peuvent etre utilisees en association avec dautres mesures biologiques comme indicateurs de changements ecologiques, une approche qui a ete utilisee avec succes dans les ecosystemes temperes pour la gestion des grands herbivores. Mots-clesgestion durable, grands herbivores, indicateurs de changement ecologique, methode de recensement, viande de brousse

ecology↗

bioRxiv2019

High sampling effectiveness for non-bee pollinators using vane traps in both open and wooded habitats

O_LINon-bee insects are important for pollination, yet few studies have assessed the effectiveness of sampling these taxa using low cost passive techniques, such as coloured vane traps, among different habitat types. C_LIO_LIThis study sampled 192 sites--108 in wooded and 84 in open habitats within an agricultural region of southern Australia. Pairs of blue and yellow vane traps were placed at each site for a period of seven days during the austral spring. C_LIO_LIOverall, 3114 flies (Diptera) from 19 families and 528 wasps (non-bee and non-formicid Hymenoptera) from 16 families were collected during the study. This sampling was representative of the region, with vane traps equally or more likely to collect as many families from both taxa as those reported on the Atlas of Living Australia (ALA) database for the sampling area. C_LIO_LIBlue vane taps (BVTs) had greater average richness of both flies and wasps and greater abundance of individuals than yellow vane traps (YVTs). BVTs were particularly favoured by certain fly and wasp families known to pollinate flowers (e.g. Syrphidae, Bombyliidae and Scoliidae), whilst YVTs sampled some less common fly families, such as Acroceridae and Bibionidae that also provide additional ecosystem services to pollination. C_LIO_LIVane traps are an effective passive sampling technique for non-bee pollinators, such as flies and wasps. This study supports the use of vane traps as a component of the sampling protocol for ecological census and population monitoring within multiple habitat types, to effectively sample a more complete pollinator community. C_LI

ecology↗

bioRxiv2019

Facets of diazotrophy in the OMZ off Peru revisited: what we could not see from a single marker gene approach

Biological dinitrogen (N2) fixation is the pathway making the large pool of atmospheric N2 available to marine life. Besides direct rate measurements, a common approach to explore the potential for N2 fixation in the ocean is a mining based on molecular genetic methods targeting the key functional gene nifH, coding for a subunit of the nitrogenase reductase. As novel sequencing and single cell techniques improved, our knowledge on the diversity of marine N2 fixers grew exponentially. However, to date one aspect of N2 fixation in the ocean is commonly left aside. This is the existence of two alternative types of nitrogenases, which are besides the Mo-Fe nitrogenase Nif, the Fe-Fe nitrogenase Anf, and the V-Fe nitrogenase Vnf, which differ with regard to their metal co-enzymes, as well as regarding their operon structure and composition. nifH-based studies may thus be biased, and alternative nitrogenases could not be recovered. Here, we screened a set of 6 metagenomes and -transcriptomes from a sulfidic water patch from the oxygen minimum zone off Peru for genes involved in N2 fixation. We identified genes related to all three nitrogenases, and generally increased diversity as compared to our previous nifH-based study from the same waters. While we could not confirm gene expression of the alternative nitrogenases from our transcriptomes, we detected additional diazotrophs involved in N2 fixation. We suggest that alternative nitrogenases may not be used under conditions present in those waters, however, depending on trace metal limitation in the future they may become active. Significance statementThis study addresses the important process of N2 fixation, based on a whole-metagenome and -transcriptome screening, reports an increased diversity of N2 fixing microbes in the sulfidic shelf water off Peru, as compared to previous target-gene based studies from the same waters. In addition to a generally higher diversity, genes encoding for alternative nitrogenases, which were previously not subject of any study on N2 fixation in oxygen minimum zones, were detected. The ecological meaning and evolutionary history of those alternative nitrogenases is subject of ongoing debates, however, their presence in OMZ waters would allow for N2 fixation at extreme anoxia, which may become important in a future ocean challenged by progressive deoxygenation.

ecology↗

bioRxiv2019

Insect herbivory and avian insectivory in novel native oak forests: divergent effects of stand size and connectivity

The value of novel native broadleaf woodlands for biodiversity conservation is important to consider for adequate forest management in rural landscapes. Passive reforestation has been proposed as a cost-efficient tool for creating networks of novel native forest stands that would help restoring biodiversity and associated ecosystem services. Yet to date the ecological functioning of such stands remains strongly understudied compared to forest remnants resulting from longer-term fragmentation. We assessed how the size and connectivity of newly established Pedunculate oak (Quercus robur L.) stands in rural landscapes of SW France affect rates of herbivory by different insect guilds as well as rates of avian insectivory and the abundance and richness of insectivorous birds. Comparing 18 novel forest stands along a gradient of size (0.04-1.15 ha) and cover of broadleaf forests in the surroundings (0-30% within a 500 radius), we found that even the smallest stands are colonised by leaf miners and chewers/skeletonizers, and that rates of herbivory are globally comparable to those reported from older and larger oak forests. The size of stands had a relatively minor effect on herbivory, whereas it increased the abundance of insectivorous bird. It also determined rates of avian insectivory as estimated by an experiment with plasticine caterpillars. These rates were however rather low and unrelated with the extent of herbivory in the stand. Overall, our study indicates that insect herbivores tend to react more rapidly to the establishment of novel native forests than their avian predators as the latter may depend on the development of larger patches of suitable habitat in the surrounding landscape. To favour a rapid build-up of diverse, and hence stable, trophic networks involving insect herbivores and their predators, woodland creation schemes should therefore primarily focus on habitat size and quality.

ecology↗

bioRxiv2019

Ammonia-oxidizing archaea release a suite of organic compounds potentially fueling prokaryotic heterotrophy in the ocean

Ammonia-oxidizing archaea (AOA) constitute a considerable fraction of microbial biomass in the global ocean, comprising 20-40% of the oceans prokaryotic plankton and thus play an important role in global nitrogen cycle. However, it remains enigmatic to what extent these chemolithoautotrophic archaea are releasing dissolved organic matter (DOM). A combination of targeted and untargeted metabolomics was used to characterise the exometabolomes of three model AOA strains of the Nitrosopumilus genus. Furthermore, we compared the composition of intra- and extracellular dissolved free amino acids (DFAA). Our results indicate that marine AOA exude a suite of organic compounds with potentially varying reactivity, dominated by nitrogen-containing compounds. A significant fraction of the released DOM consisted of labile compounds, which typically limit prokaryotic heterotrophic activity in open ocean waters, including amino acids, thymidine and B vitamins. In growing Nitrosopumilus cultures, hydrophobic amino acids were likely released as a result of passive diffusion corresponding to ammonia oxidation activity, while glycine was continuously released at high rates. Our results suggest that AOA release several ecologically and biochemically relevant metabolites, potentially fueling heterotrophic prokaryotes in the ocean.

ecology↗

bioRxiv2019

Niche partitioning and coexistence of two spiders of the genus Peucetia (Araneae, Oxyopidae) inhabiting Trichogoniopsis adenantha plants (Asterales, Asteraceae): a population approach

Niche theory suggests that the coexistence of ecologically similar species at the same site requires some form of resource partitioning that reduces or avoids interspecific competition. Here, we investigated the temporal and spatial niche differentiation of two sympatric congeneric spiders, Peucetia rubrolineata and P. flava, inhabiting Trichogoniopsis adenantha (Asteraceae) plants along an altitudinal gradient in various shaded and open areas in an Atlantic forest in Serra do Japi, SP, Brazil. In theory, the coexistence of two Peucetia species could be explained by: (1) temporal segregation; (2) differential use of the branches of the plant; (3) differential use of specific parts of the branches of the plant; (4) differential distribution in shaded and open areas; and (5) differential altitudinal distribution of the two Peucetia species. With respect to temporal niche, we observed that the two spider species had a similar age structure and similar fluctuation in abundance throughout the year. With respect to micro-habitat use, in both species, different instars used different plant parts, while the same instars of both species used the same type of substrate. However, the two Peucetia species segregated by meso-habitat type, with P. rubrolineata preferring T. adenantha plants in shaded areas and P. flava preferring those in open areas. Our results support the hypothesis of niche partitioning begetting diversity, and highlight the importance of analysing habitat use at multiple scales to understand mechanisms related to coexistence.

ecology↗

bioRxiv2019

Effect of time-series length and resolution on abundance- and trait-based early warning signals of population declines

Natural populations are increasingly threatened with collapse at the hands of anthropogenic effects. Predicting population collapse with the help of generic early warning signals (EWS) may provide a prospective tool for identifying species or populations at highest risk. However, pattern-to-process methods such as EWS have a multitude of challenges to overcome to be useful, including the low signal to noise ratio of ecological systems and the need for high quality time-series data. The inclusion of trait dynamics with EWS has been proposed as a more robust tool to predict population collapse. However, the length and resolution of available time series are highly variable from one system to another, especially when generation time is considered. As yet it remains unknown how this variability with regards to generation time will alter the efficacy of EWS. Here we take both a simulation- and experimental-based approach to assess the impacts of relative time-series length and resolution on the forecasting ability of EWS. We show that EWS performance decreases with decreasing length and resolution. Our simulations suggest a relative time-series length between ten and five generations and a resolution of half a generation are the minimum requirements for accurate forecasting by abundance-based EWS. However, when trait information is included alongside abundance-based EWS, we find positive signals at lengths and resolutions half of what was required without them. We suggest that, in systems where specific traits are known to affect demography, trait data should be monitored and included alongside abundance data to improve forecasting reliability.

ecology↗

bioRxiv2019

The restoration species pool for restoring tropical landscapes: assessment of the largest Brazilian supply chain

Brazil has been committed to fulfill international restoration goals and to enforce environmental legislation that will require private landowners to undertake ecological restoration of 21 million hectares of degraded and deforested landscapes. To support a broad range of restoration practices, a consolidated supply chain able to represent regional plant diversity is essential. This study investigated the restoration species pool in native plant nurseries in Sao Paulo state, southeastern Brazil and evaluated their geographic distribution, similarity of their plant stocks and the proportion of species represented from regional floras. Despite the lack of technical assistance and the large presence of non-native species (126 species, average 7.5 species/nursery), we found still more impressive native species richness in plant nurseries (561 species, average 86.4 species/nursery) from both the Atlantic Forest and Cerrado domains, representing 38 to 44% of regional floras. There was a huge bias toward tree and shrub species (96.6%) and absence or underrepresentation of other growth forms, as well as of savanna specialists, animal-dispersed and threatened species. The great dissimilarity of species offered in the nurseries surveyed underscores the importance of regional seed collection practices. Effective assistance and capacitation are essential to address issues related to misidentification of species, underrepresentation of most functional plant groups, and the presence of non-native species, as well as to support the supply chain, currently undergoing market downturn.\n\nAuthor contributions CYV and RRR conceived and designed the research. CYV performed data compilation; CYV and RPN analyzed the data; CYV and RAGV led the writing of the manuscript; all authors contributed to the drafts and gave final approval for publication.\n\nImplications for practiceO_LIPlant nurseries collecting propagules from the surrounding vegetation provide an adequate - but limited - restoration species pool, with very dissimilar plant stocks available among plant nurseries.\nC_LIO_LIPlant nurseries concentrate their production on shrub and tree species and sub-represent other growth forms and some functional groups such as animal-dispersed and threatened species.\nC_LIO_LIThe diversity of the restoration species pool is the basis to support a broad range of restoration practice, being essential to boost restoration initiatives that complement and support the conservation of remaining diversity in human modified landscapes.\nC_LIO_LIEffective assistance and capacity building should be provided to address issues related to misidentification, underrepresentation of functional groups and the presence of exotic and invasive species, as well as to support the supply chain, currently under market downturn\nC_LI

ecology↗

bioRxiv2019

Distinct defense strategies allow different grassland species to cope with root herbivore attack

O_LIRoot-feeding insect herbivores are of substantial evolutionary, ecological and economical importance. Plants can resist insect herbivores through a variety of tolerance and resistance strategies. To date, few studies have systematically assessed the prevalence and importance of these strategies for root-herbivore interactions across different plant species.\nC_LIO_LIHere, we characterize the defense strategies used by three different grassland species to cope with a generalist root herbivore, the larvae of the European cockchafer Melolontha melolontha.\nC_LIO_LIOur results reveal that the different plant species rely on distinct sets of defense strategies. The spotted knapweed (Centaurea stoebe) resists attack by dissuading the larvae through the release of repellent chemicals. White clover (Trifolium repens) does not repel the herbivore, but reduces feeding, most likely through structural defenses and low nutritional quality. Finally, the common dandelion (Taraxacum officinale) allows M. melolontha to feed abundantly but compensates for tissue loss through induced regrowth.\nC_LIO_LISynthesis: Three co-occurring plant species have evolved different solutions to defend themselves against attack by a generalist root herbivore. The different root defense strategies may reflect distinct defense syndromes.\nC_LI

ecology↗

bioRxiv2019

Conserving unprotected important coastal habitats in the Yellow Sea: shorebird occurrence, distribution and food resources at Lianyungang

The authors have withdrawn their manuscript since this preprint contain errors which have been corrected in the version published in the journal Global Ecology and Conservation (doi: 10.1016/j.gecco.2019.e00724). Therefore, the authors do not wish this preprint to be cited as reference for the project. If you have any questions, please contact the corresponding author.

ecology↗

bioRxiv2019

Changes in the Physicochemical Properties and Microbial Communities of Rhizospheric Soil after Cassava/Peanut Intercropping

Cassava/peanut intercropping is a popular cultivation method in southern China and has the advantages of apparently increased yield and economic efficiency compared with monoculture, however, the ecological benefits of this method are poorly understood. This study aimed to investigate the effects of intercropping on the physicochemical properties and microbial community structures of soil. Field trials were performed to determine the effects of cassava/peanut intercropping on rhizospheric soil nutrient content, enzyme activities, microbial quantity and microbial community structure. The microbial community was characterized by 16S rRNA tag-based high-throughput sequencing on the Illumina MiSeq platform. Results showed that cassava/peanut intercropping could improve the physicochemical properties of rhizospheric soil by increasing the available nutrient content, pH, bacterial quantity, and some enzyme activities and by altering the microbial community structure. 16S rRNA gene sequencing demonstrated that the microbial community structure varied between the intercropping and monoculture systems. Nitrospirae, Verrucomicrobia and Gemmatimonadetes were more abundant in the intercropping system than in the monocultures. Redundancy analysis (RDA) revealed that the abundances of DA101, Pilimelia and Ramlibacter were positively correlated with environmental parameters such as available nitrogen and pH, and these were dominant genera in the rhizospheric soil of the intercropped peanut plants.

ecology↗

bioRxiv2019

An experimental manipulation of species’ phenologies overturns competitive hierarchies

Ecological theory produces opposing predictions about whether differences in the timing of life history transitions, or phenology, promote or limit coexistence. Phenological separation is predicted to create temporal niche differences, increasing coexistence, yet phenological separation may competitively favour one species, increasing fitness differences and hindering coexistence. We experimentally manipulated relative germination timing, a critical phenological event, of two annual grass species, Vulpia microstachys and V. octoflora, to test these contrasting predictions. We parameterized a competition model to estimate within-season niche differences, fitness differences, and coexistence, and to estimate coexistence when among-year fluctuations of germination timing occur. Increasing germination separation caused parallel changes in niche and fitness differences, with the net effect of weakening within-year coexistence. Both species experienced a competitive advantage by germinating earlier, strongly enough to allow the generally inferior competitor to exclude the other with at least a four day head start. The overall consequence of germination separation was to limit coexistence within a given year, although among-year variation in relative timing of germination was sufficient to support long-term coexistence. Our results clarify how phenological differences structure competitive interactions, and highlight the need to quantify among-year variation in these differences to better understand species coexistence.

ecology↗

bioRxiv2019

Low marine food levels mitigate high migration costs in anadromous populations

Migratory fish populations, like salmon, have dramatically declined for decades. Because of their extensive and energetically costly breeding travel anadromous fish are sensitive to a variety of environmental threats, in particular infrastructure building in freshwater streams and food declines in the ocean. Here, we analyze the effects of these two threats combined. Unexpectedly, we find that low marine food availabilities favor, as opposed to threaten, the ecological success of endangered populations. This counterintuitive effect results from an aspect of individual energetics that individuals switching to higher food levels reach larger sizes with concomitant larger migration costs but have lower energy densities. Surprisingly, the decline of food levels in the ocean after the completion of dams may thus mitigate the risk of extinction of migratory fish populations. This highlights the need of a mechanistic understanding integrating individual energetics, life history, and population dynamics to accurately assess biological consequences of environmental change.

ecology↗

bioRxiv2019

The distinct phenotypic signatures of dispersal and stress in an arthropod model: from physiology to life history

Dispersing individuals are expected to encounter costs during transfer and in the novel environment, and may also have experienced stress in their natal patch. Given this, a non-random subset of the population should engage in dispersal and eventually show divergent stress-related responses towards new conditions. Dispersal allows escape from stress, but is equally subjecting individuals to it.\n\nPhysiological shifts expressed in the metabolome form a major part of responses to stress exposure and are expected to be associated with the dispersal phenotype, thereby shaping physiological dispersal syndromes. We analyzed how metabolic profiles and life-history traits varied between dispersers and residents of the model two-spotted spider mite Tetranychus urticae, and whether and how these syndromes varied with exposure to a stressful new host plant (tomato). Regardless of the effect of host plant, we found a physiological dispersal syndrome where, relative to philopatric individuals, dispersers were characterized by lower leaf consumption rates and a lower concentration of several amino acids, indicating a potential dispersal-foraging trade-off. As a possible consequence of this lower food intake, dispersers also showed a lower reproductive performance. Responses to tomato exposure were consistent with this plant being a stressor for Tetranychus urticae, including reduced fecundity and reduced feeding by mites. Tomato-exposed mites laid larger eggs, which can be interpreted as a plastic response to food stress, increasing the likelihood of survival to maturity. Contrary to what could be expected from the costs of dispersal and stress resistance and from previous meta-population level studies, there was no interaction between dispersal status and host plant for any of the examined traits, indicating that the impacts of a new stressful host plant are equally incurred by residents and dispersers.\n\nWe thus provide novel insights in the processes that shape dispersal and the putative feedbacks on ecological dynamics in spatially structured populations.

ecology↗

bioRxiv2019

The planktonic protist interactome: emerging trends after a century of research

Microbial interactions are crucial for Earth ecosystem function, yet our knowledge about them is limited and has so far mainly existed as scattered records. Here, we have surveyed the literature involving planktonic protist interactions and gathered the information in a manually curated Protist Interaction DAtabase (PIDA). In total, we have registered ~2,500 ecological interactions from ~500 publications, spanning the last 150 years. All major protistan lineages were involved in interactions as hosts, symbionts, parasites, predators and/or prey. Symbiosis was the most common interaction (43% of all records), followed by predation (39%) and parasitism (18%). Using bipartite networks, we found that protistan predators seem to be \"multivorous\", while parasite-host and symbiont-host interactions appear to have moderate degrees of specialization. The SAR supergroup (i.e. Stramenopiles, Alveolata and Rhizaria) heavily dominated PIDA, and comparisons against a global-ocean molecular survey (TARA Oceans) indicated that several SAR lineages, which are abundant and diverse in the marine realm, were underrepresented among the compiled interactions. All in all, despite historical biases, our work not only unveils large-scale eco-evolutionary trends in the protist interactome, but it also constitutes an expandable resource to investigate protist interactions and to test hypotheses deriving from omics tools.

ecology↗

bioRxiv2019

Segregation of floricolous ants along latitudinal and urbanization gradients

Recent call has been made to study the biogeography of species interactions in order to better understand ecosystems states and processes, as well as their response to global anthropogenic disturbances. Ants (Formicidae) are a dominant group of arthropods with a central role in ecosystem functioning. Many ant species, those feeding on liquids, are floricolous and consume nectar. The biogeography of ant-flower interactions is still poorly studied and especially in temperate area. Here we quantify variations in ant-flower interaction frequency in response to latitudinal and urbanization gradients at a country scale.\n\nWe used data from a flower-visitor monitoring program that includes pictures on 2511 flower plants across Continental France (Mainland) and over 4 years. We analysed the occurrence of the ant-flower interactions along two gradients: latitude and urbanization, this for 10 ant taxa corresponding to different taxonomical level (from family to species).\n\nAnts visited 26 % of the sampled plants. Most of the observed ant-flower interaction involved the subfamily Formicinae (82.1 %), followed by Myrmicinae and Dolichoderinae (6.9 % and 4.6 % respectively). Globally, (i) the probability of occurrence was negatively related to latitudes (ii) and to urbanization at lower latitude. (iii) Responses to latitude among sub families, genus and species level responses were segregated and taxonomically aggregated.\n\nAt lower taxonomic levels we found clear latitudinal niche partitioning among ant taxa suggesting that competition, on both evolutionary and ecological time scales, is a major process structuring ant communities. Finally, our results highlight that the effects of large scale perturbation like urbanization can vary and affect latitudinal gradient.

ecology↗

bioRxiv2019

A test of the evolution of increased competitive ability in two invaded regions

O_LIFinding patterns that predict and explain the success of non-native species has been an important focus in invasion ecology. The evolution of increased competitive ability (EICA) hypothesis has been a frequently used framework to understand invasion success. Evolution of increased competitive ability predicts that 1. Non-native populations will escape from coevolved specialist herbivores and this release from specialist herbivores should result in relaxed selection pressure on specialist-related defense traits, 2. There will be a trade-off between allocation of resources for resistance against specialist herbivores and allocation to traits related to competitive ability and 3. This shift will allow more allocation to competitive ability traits.\nC_LIO_LIWe tested the predictions of EICA in the model plant Mimulus guttatus, a native of western North America (WNA). We compared how well the predictions of EICA fit patterns in two non-native regions, the United Kingdom (UK) and eastern North America (ENA). Coupled with extensive herbivore surveys we quantified genetic variation for herbivore resistance traits and fitness/ competitive ability traits to test adherence to the predictions of EICA in a common greenhouse environment.\nC_LIO_LIHerbivore communities differed significantly between WNA, UK, and ENA populations with evidence of specialist herbivore escape in the UK, but not necessarily the ENA plants. Compared to native plants, resistance traits were lower in non-native UK plants with the exception of trichome density, while the non-native ENA plants had equivalent or higher levels of herbivore resistance traits. The UK plants had increased competitive traits than native plants while the ENA plants had equivalent competitive traits to native plants. The UK plants, but not the ENA plants, showed some signs of tradeoffs between resistance traits and fitness/ competitive ability.\nC_LIO_LISynthesis. Plants from the UK conformed to predictions of EICA more closely than those from ENA. The UK invasion is an older, more successful invasion, suggesting that support for EICA may be highest in more successful invasions. The lack of comprehensive conformity of either non-native region to the predictions of EICA also leaves room for other hypotheses that may add to our mechanistic understanding of the success of non-native plant invasions.\nC_LI

ecology↗

bioRxiv2019

Predicting primary production in the southern California Current Ecosystem from chlorophyll, nutrient concentrations, and irradiance

We investigated the processes driving variability in primary productivity in the California Current Ecosystem (CCE) in order to develop an algorithm for predicting primary productivity from in situ irradiance, nutrient, and chlorophyll (chl) measurements. Primary productivity data from seven process cruises of the CCE Long-Term Ecological Research (CCE LTER) program were used to parameterize the algorithm. An initial algorithm was developed using only irradiance to predict chl-specific productivity was found to have model-data misfit that was correlated with NH4+ concentrations. We thus found that the best estimates of primary productivity were obtained using an equation including NH4+ and irradiance: PP/Chl = V0mx(1-exp(-xPAR/V0m)xNH4/(NH4+KS), where PP/Chl is chlorophyll-specific primary production in units of mg C d-1 / mg Chl, PAR is photosynthetically active radiation (units of Ei m-2 s-1), NH4+ is in units of mol L-1, V0m = 66.5 mg C d-1 / mg Chl, = 1.5, and KS = 0.025 mol L-1. We then used this algorithm to compute primary productivity rates for the CCE-P1706 cruise on which in situ primary productivity samples were not available. We compared these estimates to independent productivity estimates derived from protistan grazing dilution experiments and found excellent agreement.

ecology↗