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The ongoing and increasing worldwide demand for fish has caused a steady increase in aquaculture production during the last decades. This emphasizes the importance of farming systems with a low ecological footprint, like recirculating aquaculture systems (RAS), which are an alternative to traditional open systems. Furthermore, implementing microalgae treatments in RAS, sustainable water management and low discharge of concentrated wastewater could be achieved, allowing its reuse in the system. The influence of three factors on microalgae treatment efficiency in RAS water were studied: i) microalgae species (Chlorella vulgaris, Tetradesmus obliquus), ii) water pre-treatment (sterile filtration), and iii) sampling location within the RAS (e.g. from fish tank, after UV-disinfection, etc.). To this end, fully factorial, replicated cultivations were carried out in 100-ml flasks, and nutrient removal, microalgae growth, and density of bacteria and protozoa were measured for up to 18 days. Results show that both species are able to grow in RAS water and effectively remove nutrients in it, yet their performance depended greatly on water quality. In sterile RAS water, growth and nutrient removal efficiency of C. vulgaris surpassed that of T. obliquus. In non-sterile RAS water, the pattern reversed because of grazing proto- zoa. The location of sampling within the RAS had no discernible effect on microalgae growth or nutrient removal efficiency. The results confirm that a microalgae-based technology to treat and valorise RAS water is technically feasible, yet caution that inferences made can be reversed depending on the choice of the species and the pre- treatment of the RAS water prior to cultivation.
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The viruses that cause dengue fever, Zika and chikungunya are transmitted by the mosquito, Aedes aegypti and threaten global public health. Current vaccines and treatments against these viruses along with methods of mosquito control are of limited efficacy and novel interventions are needed. Wolbachia are bacteria that inhabit insect cells and have been found to reduce viral infection, a phenotype that is referred to as viral ‘blocking’. Although not naturally found in A. aegypti, Wolbachia were stably introduced into this mosquito in 20115 and have been shown to reduce the transmission potential of dengue, Zika and chikungunya. Trials in the tropics show that Wolbachia can spread through A. aegypti populations and reduce the local incidence of dengue fever. Despite this, the stability of viral blocking over time is unknown. Here, we reveal genes in A. aegypti that appear to affect the strength of Wolbachia-mediated dengue blocking in response to selection. We find that mosquito genotypes associated with weaker dengue blocking have reduced fitness, suggesting that there is potential for blocking to be maintained by selection. These results will inform the use of Wolbachia as biocontrol agents against mosquito-borne viruses and direct further research into measuring and improving their efficacy.
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The mitochondrial genomes (mitogenomes) of plants are known to incorporate and accumulate DNA from intra- and extracellular donors. Despite the intimate relationships formed between flowing plants (angiosperms) and fungi, lengthy fungal-like sequence has not been identified in angiosperm mitogenomes to date. Here we present multiple lines of evidence documenting horizontal gene transfer (HGT) between the mitogenomes of fungi and the ancestors of the orchids, plants that are obligate parasites of fungi during their early development. We show that the ancestor of the orchids acquired an approximately 270 bp fungal mitogenomic region containing three transfer RNA genes. We propose that the short HGT was later replaced by a second HGT event transferring more than 8 kb and 14 genes from a fungal mitogenome to that of the ancestor of the largest orchid subfamily, Epidendroideae. Our results represent the first evidence of genomic-scale HGT between fungal and angiosperm mitogenomes and demonstrate that the length intergenic spacer regions of angiosperm mitogenomes can effectively fossilize the genomic remains of ancient, non-plant organisms.
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Plant traits are critical to plant form and function —including growth, survival and reproduction— and therefore shape fundamental aspects of population and ecosystem dynamics as well as ecosystem services. Here, we present a global species-level compilation of key functional traits for palms (Arecaceae), a plant family with keystone importance in tropical and subtropical ecosystems. We derived measurements of essential functional traits for all (>2500) palm species from key sources such as monographs, books, other scientific publications, as well as herbarium collections. This includes traits related to growth form, stems, armature, leaves and fruits. Although many species are still lacking trait information, the standardized and global coverage of the data set will be important for supporting future studies in tropical ecology, rainforest evolution, paleoecology, biogeography, macroecology, macroevolution, global change biology and conservation. Potential uses are comparative eco-evolutionary studies, ecological research on community dynamics, plant-animal interactions and ecosystem functioning, studies on plant-based ecosystem services, as well as conservation science concerned with the loss and restoration of functional diversity in a changing world.
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Cetaceans possess brains that rank among the largest to have ever evolved, either in terms of absolute mass or relative to body size. Cetaceans have evolved these huge brains under relatively unique environmental conditions, making them a fascinating case study to investigate the constraints and selection pressures that shape how brains evolve. Indeed, cetaceans have some unusual neuroanatomical features, including a thin but highly folded cerebrum with low cortical neuron density, as well as many structural adaptations associated with acoustic communication. Previous reports also suggest that at least some cetaceans have an expanded cerebellum, a brain structure with wide-ranging functions in adaptive filtering of sensory information, the control of motor actions, and cognition. Here, we report that, relative to the size of the rest of the brain, both the cerebrum and cerebellum are dramatically enlarged in cetaceans and show evidence of co-evolution, a pattern of brain evolution that is convergent with primates. However, we also highlight several branches where cortico-cerebellar co-evolution may be partially decoupled, suggesting these structures can respond to independent selection pressures. Across cetaceans, we find no evidence of a simple linear relationship between either cerebrum and cerebellum size and the complexity of social ecology or acoustic communication, but do find evidence that their expansion may be associated with dietary breadth. In addition, our results suggest that major increases in both cerebrum and cerebellum size occurred early in cetacean evolution, prior to the origin of the major extant clades, and predate the evolution of echolocation.
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Phenological investigation can provide valuable insights into the ecological effects of climate change. Appropriate modelling of the time distribution of phenological events is key to determining the nature of any changes, as well as the driving mechanisms behind those changes. Here we present the nlstimedist R package, a distribution function and modelling framework that describes the temporal dynamics of unimodal phenological events. The distribution function is derived from first principles and generates three biologically interpretable parameters. Using seed germination at different temperatures as an example, we show how the influence of environmental factors on a phenological process can be determined from the quantitative model parameters. The value of this model is its ability to represent various unimodal temporal processes statistically. The three intuitively meaningful parameters of the model can make useful comparisons between different time periods, geographical locations or species’ populations, in turn allowing exploration of possible causes.
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Oryctocephalid trilobites are seldom abundant and often tectonically deformed, creating problems for robust species delimitation and compromising their utility in biostratigraphic and evolutionary studies. By studying more than 140 specimens recovered from the upper portion of the Combined Metals Member (Pioche Formation, Nevada; Cambrian Stage 4, Series 2), we exploit a rare opportunity to explore how morphological variation among oryctocephalid specimens is partitioned into intraspecific variation versus interspecific disparity. Qualitative and quantitative analyses reveal that two species are represented: Oryctocephalites palmeri Sundberg and McCollum, 1997 and Oryctocephalites sp. A, the latter known from a single cranidium stratigraphically below all occurrences of the former. In contrast to the conclusions of a previous study, there is no evidence of cranidial dimorphism in O. palmeri. However, that species exhibits considerable variation in cranidial shape and pygidial spine arrangement and number. Cranidial shape variation within O. palmeri is approximately one-half of the among-species disparity within the genus. Comparison of cranidial shape between noncompacted and compacted samples reveals that compaction causes significant change in mean shape and an increase in shape variation; such changes are interpretable in terms of observed fracture patterns. Nontaphonomic variation is partitioned into ontogenetic and nonallometric components. Those components share similar structure with each other and with interspecific disparity, suggesting that ontogenetic shape change might be an important source of variation available for selection. This highlights the importance of ontogenetic and taphonomic sources of variation with respect to species delimitation, morphospace occupation, and investigation of evolutionary patterns and processes.
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1. Long-term pathogen control or eradication in wildlife is rare and represents a major challenge in conservation. Control is particularly difficult for environmentally transmitted pathogens, including some of the most conservation-critical wildlife diseases. 2. We undertook a treatment program aimed at population-scale eradication of the environmentally transmitted Sarcoptes scabiei mite (causative agent of sarcoptic mange) during an epizootic in bare-nosed wombats (Vombatus ursinus). Field trial results were used to parameterize a mechanistic host-disease model that explicitly described indirect-transmission, host behaviour, and viable disease intervention methods. 3. Model analysis shows that elimination of S. scabiei in the wild is most sensitive to the success of treatment delivery, and duration of the program. In addition, we found the frequency that wombats switch burrows was an important positive driver of mite persistence. 4. Synthesis and applications: This research emphasises the utility of applying model-guided management techniques in order to achieve practical solutions in the field. Our approach and findings have applicability to other species affected by S. scabiei (e.g., wolves, red foxes, Spanish ibex, and American black bear), as well as other conservation-critical systems involving environmental transmission (e.g., bat white-nose syndrome and amphibian chytridiomycosis).
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Aim: Understanding how landscape features affect gene flow is critical to connectivity conservation and restoration management. Here, we examined the relationship between functional connectivity (gene flow) and structural connectivity (area and spatial configuration of habitats) in three co-occurring short-range plant taxa in an ancient terrestrial island system. Location: Low altitude mountain ranges south-western Australia Methods: We analysed spatial patterns of genetic differentiation at nuclear microsatellite loci using Bayesian clustering. Circuit theory modelling was used to generate all possible pathways that connect populations as resistance distance matrices based on two surfaces for each taxon. The first surface assumes a flat terrain and tests whether genetic similarity declines only with distance – isolation by distance (IBD). The second surface is habitat suitability based on species distribution modelling (SDM), which tests whether genetic similarity is a function of connected and suitable habitat. Multiple matrix regression with randomisation was used to test the significance of the resistance distance matrices at predicting two metrics of genetic differentiation (FST and DEST). Variance explained was partitioned using redundancy analysis. Results: Genetic structure for the insect-pollinated taxa - Acacia adinophylla, and Tetratheca aphylla subsp. aphylla was at similar spatial scales. Unexpectedly, a higher level of genetic structure was found in the wind-pollinated Lepidosperma bungalbin. IBD best explained the gene flow of A. adinophylla (R2 = 0.41-0.43) with partial support provided by habitat suitability (R2 = 0.04-0.07). In contrast, connectivity by habitat suitability was highest for T. aphylla subsp. aphylla (R2 = 0.56-0.59). Drivers of L. bungalbin connectivity were inconsistent between the two measures of genetic differentiation. Main conclusions: Gene flow is facilitated by different factors for the three taxa. Habitat fragmentation would most strongly impede gene flow for T. aphylla subsp. aphylla. Geographic distance cannot be assumed as the sole or best determinant of gene flow among populations, nor can findings be generalised to coexisting taxa.
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Acer (the maple genus) is one of the diverse tree genera in the Northern Hemisphere with about152 species, most of which are in eastern Asia. There are roughly a dozen of species in Europe/western Asia and a dozen in North America. Several phylogenetic studies of Acer have been conducted since 1998, but none have provided a satisfactory resolution for basal relationships among sections of Acer. Here we report the first well-resolved phylogeny of Acer based on DNA sequences of over 500 nuclear loci generated using the anchored hybrid enrichment method and explore the implications of the robust phylogeny for Acer systematics and biogeography. Our phylogenetic results support the most recent taxonomic treatment of Acer by de Jong with some modifications; section Pentaphylla may be expanded to include section Trifoliata, and A. yangbiense may be included in section Lithocarpa. Sections Spicata, Negundo, Arguta, and Palmata form a clade sister to the rest of the genus where sections Glabra and Parviflora comprise the first clade followed by section Macrantha, sections Ginnala, Lithocarpa, Indivisa, sections Platanoidea and Macrophylla, section Rubra, section Acer, and section Pentaphylla. Monotypic sections Glabra and Macrophylla in North America are sister to the Japanese section Parviflora and Eurasian section Platanoidea, respectively. Ancestral area inferences using S-DIVA (statistical dispersal and vicariance analysis) and DEC (dispersal and extinction cladogenesis) methods suggest that Asia might be the most likely ancestral area of Acer as proposed by Wolfe and Tanai and molecular dating using BEAST (Bayesian evolutionary analysis by sampling trees) indicate that section diversifications of Acer might have completed largely in the late Eocene and the intercontinental disjunctions of Acer between eastern Asia and eastern North America formed mostly in the Miocene.
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