Ecological Similarity Research Articles

DNA metabarcoding study of the diet and feeding preferences of the Grey Plover (Pluvialis squatarola) during migration on the SW Black Sea coast, Bulgaria

We studied the diet composition and feeding preferences of the Grey Plover (Pluvialis squatarola) at its migration stopover at Pomorie Lake on the South-Western Black Sea coast, Bulgaria, through DNA metabarcoding of faeces. Faecal samples were collected in autumn 2020 and spring 2021, preserved in 95% ethanol, and stored at -20ºC until DNA extraction and metabarcoding. Two molecular markers were initially targeted - ITS2 for plant identification, and CO1 for animal identification; however, the subsequent analyses focused on the dominant animal prey identified by CO1. Concurrently, coastal habitats where the birds were observed to feed, such as the surf zone and the sandy supralittoral shore, were also sampled to determine prey availability. The Grey Plover had a broad diet spectrum, with 332 prey taxa in total identified by metabarcoding, belonging to 7 phyla, 14 classes, 24 orders, 78 families and 119 genera. The birds consumed both terrestrial and marine taxa, suggesting that multiple coastal habitats are used for foraging. Terrestrial arthropods, particularly insects, predominated in the diet, while mytilid bivalves were the most represented marine taxon. The results suggest that at the studied migration stopover site at the SW Black Sea, the Grey Plover was a generalist feeder, which agrees with previous studies from different areas. Most birds fed on insects (Diptera, Lepidoptera, Hymenoptera); a few individuals also specialised on marine molluscs, arachnids and polychaetes. The most abundant potential prey in the environ­ment were not the most frequently consumed, possibly because the sampling methods were not suitable for the full spectrum of available prey (particularly the flying insects). We found limited seasonal variation in Grey Plover diet composition and preferences, with the proportions of some prey taxa differing slightly between seasons, probably due to seasonal variations in their abundance and activity in coastal habitats. Our results contribute to the knowledge of Grey Plover diet, prey choice and habitat use in a little-studied region on the Black Sea-Mediterranean Flyway. The new information could contribute towards designing effective conservation measures to preserve habitat quality at stopover sites for this wader and others with similar ecology, ensuring migration success at a time when migratory bird populations are increasingly threatened by habitat loss and degradation. The results are presented and analysed in detail in Vassileva et al. (2024). The full CO1 dataset is available in BOLD (https://doi.org/10.5883/DS-PLUVS).

How many bees fit in the city? A spatial ecological case study to conserve urban wild bees

Pollination is crucial for biodiversity and food security, with bees playing a significant role. The growing popularity of urban beekeeping is leading to increasing honeybee densities in cities, raising concerns about competition for pollen and nectar with wild bees due to limited foraging resources in densely urbanized areas. To assess the current bee occurrences of wild and honeybees in urbanized and protected areas of a Central European city, we focused on the ecological similarities between honeybees and wild bees. We compiled an inventory of 462 wild bee species documented since 1990 in Vienna (Austria) and conducted a survey of apiary locations in cooperation with beekeepers. We calculated apiary densities and indices for species richness, rarity, and, based on flower-visiting traits, the trait similarity between honeybees and wild bees. We found that approximately four times more honeybee colonies were kept in central Vienna in 2023 than the habitat may support. In parts of Vienna’s nature conservation areas, the number of colonies also exceeded the density of 3.5 colonies per km² recommended by the literature. Results indicate a significant spatial overlap of high apiary densities and wild bee hotspots, particularly in urban nature conservation areas like Natura 2000 protected areas. In Natura 2000 areas, the trait similarity of rare wild bee species was significantly increased, indicating a potential elevated competition between wild bees and honeybees for floral resources. This study highlights the need for spatial planning to balance urban beekeeping and wild bee conservation, recommending actions to match habitat quality to apiary densities to mitigate competitive pressures.

An Updated Environmental Resistance Model for Predicting the Spread of Invasive Species

ABSTRACTAimPredictive models on invasive species spread can assist in identifying large‐scale invasion risk. Environmental resistance (ER) models, which predict spread based on ecological similarity to already‐invaded communities, offer one approach. However, gaps remain in understanding how different ER measurements perform across different taxa and how they can be integrated with future global change. Here, we aim to discern the primary drivers of invasion spread by comparing different ER models and then use the best models to forecast future invasion dynamics.LocationEastern US.Taxa1873 invasive plants and animals.MethodsWe developed different ER measurements, including biotic similarities among native plants in their species and phylogenetic assemblages, and functional traits, and abiotic similarities in climate, soil, and human disturbances. We obtained the best ER model for each invasive species to evaluate their potential invasion extents; and we further predicted their future range shifts under climate change.ResultsNative plant similarities provided the best proxy measure of ER for both invasive plants and animals. Invasion hotspots were identified in urban and coastal areas, and the predicted potential invasion ranges under current conditions extended from these hotspots to the neighboring areas. The invasion range for most invasives was predicted to increase under future climate change, with Arthropoda and Tracheophyta generally expanding the most among all taxa. The invasives that are predicted to expand their range in the future have already occupied larger areas than the invasives whose ranges are predicted to contract.Main ConclusionsThese results highlight the importance of maintaining diverse native communities in invasion control and raise the concern of increased invasion risk in the future. Our findings call for more efforts on invasion monitoring in areas near large cities, and increased capacity for early detection and rapid response to prevent the current invasives spreading more widely.

Dietary and competition effects on life history attributes of Chrysomya megacephala and Lucilia sericata (Diptera: Calliphoridae) in south-west Europe.

The range of the oriental latrine fly (Chrysomya megacephala) is currently expanding. It coexists with another blowfly with a similar ecology, the green bottle fly (Lucilia sericata), one of the most abundant species in carrion during warm months. It is essential to understand the influence of temperature, larval substrate type, and larval competition on the development rates of these necrophagous calliphorids to evaluate the role and the adaptation of C. megacephala in the ecosystems, and on the necrophagous Diptera community. Moreover, due to the forensic importance of both species, biological data are need for forensic purposes in south-west Europe. This study represents the first on the biology of C. megacephala in Europe, and of L. sericata in Spain. We performed a field experiment in Alicante province (south-east Spain) to analyse the monthly abundance of both species in natural conditions, and three lab rearing experiments involving both species to evaluate (i) development at constant temperatures, (ii) the growth of larvae and pupae on different substrates, and (iii) coexistence in pure and mixed cultures under controlled abiotic conditions. The results allowed us to analyse the biological differences between both species, and their effects on the forensic entomology application.

Silage Yield and Quality of Forage Peas and Hungarian Vetch and Triticale Binary Mixtures

This study was conducted in order to determine silage quality in binary mixtures of forage pea (Pisum sativum ssp. arvense L. "FP") and Hungarian vetch (Vicia pannonica C. "HV") and triticale (X triticosecale Wittmack. "T") in 2021-2022 vegetation period. Hungarian vetch and forage pea and triticale seeds were sown in 6 different mixture ratios (legume/triticale; 100%/0, 80/20%, 60/40%, 40/60%, 20/80%). The experiment was established according to randomized blocks experimental design with 3 replications. In the study, dry matter content, pH, flieg score, quality class, crude protein, ADF, NDF, Ca, K, Mg, P, lactic acid and acetic acid contents were analyzed for silage yield and quality. The dry matter of silages was between 23.83 and 36.49%, while the pH was between 4.57 and 5.18. The highest crude protein was determined in pure forage peas (22%) and it was determined that it increased in parallel with the increase in the legume ratio in the mixture. Mineral contents were found to be high in sole and intense legume silages, similar to crude protein. In terms of silage quality in the examined parameters, mixed sowing gave better results than sole sowing. As a result of the study, 80:20 T/HV mixture ratio sowing is recommended for Yozgat and regions with similar ecology in terms of silage yield and quality.

Trophic Structure and Isotopic Niche of Invaded Benthic Communities on Tropical Rocky Shores.

When a species is introduced in a new location, it is common for it to establish itself when it finds favorable conditions in the receptor community with regard to interspecific interactions with native species. The azooxanthellate corals Tubastraea coccinea and Tubastraea tagusensis are invasive species introduced in the Caribbean Sea, the Gulf of Mexico, and the Brazilian Southwest Atlantic. They are successful competitors for space, have multiple reproductive modes, and have high larval dispersion and recruitment, but studies on food and trophic relationships of the genus Tubastraea are still scarce. In the present study, we used isotopic values of δ13C and δ15N to investigate trophic relationships in rocky shore communities invaded by T. tagusensis and T. coccinea corals under different oceanographic and anthropogenic contexts. Using metrics derived from the isotopic values, we show that invaded communities have a lower degree of trophic diversity, with species characterized by similar trophic ecologies while abiotic factors seem to contribute to the biotic resistance of communities exposed to invasion events. Tubastraea spp. occupy a niche space similar to that occupied by the native community of suspension feeders, sharing resources already consumed by the receptor community, which makes invading corals successful competitors for food.

Prey availability and diet composition of the Grey plover (Pluvialis squatarola) during migration on the South-Western Black Sea coast, Bulgaria

Migratory waders use stopover sites to refuel for the next stages of their migration, relying on seasonally abundant prey. Migration success depends on food quality and availability at these key sites. We studied the diet composition and preferences of the Grey Plover (Pluvialis squatarola) at its migration stopover at Pomorie Lake on the South-Western Black Sea coast, Bulgaria through DNA metabarcoding of faeces collected in autumn 2020 and spring 2021. Prey availability samples were also collected from the surf zone and the supralittoral sandy shore habitats in the study area.Grey Plover had a broad diet spectrum, with 332 prey taxa in total identified by metabarcoding. Both terrestrial and marine taxa were found, suggesting that the birds use multiple coastal habitats for foraging. Terrestrial arthropods, particularly insects, predominated in the Grey Plover diet; mytilid bivalves were the most represented marine taxon. The birds had a generalist feeding strategy, with diverse prey items eaten in small quantities. Most Grey Plovers fed on insects (Diptera, Lepidoptera, Hymenoptera), but some individuals showed specialisation for other taxa (mussels, spiders, polychaetes). The most abundant potential prey in the environment were not the most frequently consumed, but it is possible the prey sampling failed to capture the whole spectrum of available prey due to methodological limitations.We found no significant seasonal variation in Grey Plover diet composition, but the proportions of some prey taxa in the diet changed slightly, probably reflecting seasonal differences in their abundance and activity in coastal habitats.Our results contribute to the knowledge of Grey Plover diet, prey choice and habitat use in a little-studied region, and could help design effective conservation measures to preserve habitat quality at stopover sites for this wader and others with similar ecology.

Host trees partially explain the complex bacterial communities of two threatened saproxylic beetles.

Microorganisms are integral to ecosystem functioning and host adaptation, yet the understanding of microbiomes in diverse beetle taxa remains limited. We conducted a comprehensive study to investigate the microbial composition of two red flat bark beetle species, Cucujus haematodes and C. cinnaberinus, and assessed the influence of host taxonomic relatedness and host tree species on their microbiomes. We sampled 67 larvae of two Cucujus taxa taken from 11 host tree species. 16S rRNA V4 fragment sequencing revealed distinct microbial communities associated with each Cucujus species, with host tree species significantly influencing microbiome composition. Alpha and beta diversity metrics indicated significant differences between microbial communities in both beetle and host tree species. Principal component analysis indicated distinct clustering based on host tree species but not for beetle species. This overlap could be attributed to the similar ecology of both Cucujus species. The detection of various bacteria, among which some have already been reported in saproxylophagous beetles, suggests that the red flat bark beetles ingest the bacteria via foraging on other wood-dwelling invertebrates. Our findings show the complex interplay between host taxonomy, microhabitat and microbial composition in Cucujus, providing insights into their ecological roles and conservation implications. This research helps to fill the gap in understanding the microbial dynamics of saproxylic beetles, sheds light on factors shaping their microbiomes and highlights the importance of considering both host species and environmental conditions when studying insect-microbe interactions in forest ecosystems.

Highland forest dynamics across equatorial East Africa during the end of the African humid period

Tropical mountain ecosystems hold immense ecological and economic importance, yet they face disproportionate risks from shifting tropical climates. For example, present-day montane vegetation of East Africa is characterized by different plant species that grow in and are restricted to certain elevations due to environmental tolerances. As climate changes and temperature/rainfall zones move on mountains, these species must rapidly adjust their ranges or risk extinction.Paleoenvironmental records offer valuable insights into past climate and ecosystem dynamics, aiding predictions for ongoing climate change impacts. In particular, warming and wetting in tropical East Africa during the mid-Holocene resulted in both lowland and highland forest expansion. However, the relative impacts of rainfall and temperature change on montane ecosystems along with the influence of lowland forest expansion on montane communities is not completely understood. We use fossil pollen to study the vegetation changes in two lakes at different altitudes in the Rwenzori Mountains, Uganda: Lake Mahoma (Montane Forest belt) and Upper Kachope Lake (Afroalpine belt). Further, using the newly relaunched African Pollen Database and recent temperature reconstructions, we provide a regional synthesis of vegetation changes in the Rwenzori and then compare this with changes observed from other equatorial East African montane sites (particularly Mt Kenya).In the early to mid-Holocene in the Rwenzori Mountains, trees common today in lowland forests dominated, driven largely by warmer temperatures. After 4000 years ago (4ka), Afromontane forest trees along with grasses progressively replaced lowland trees. Not all sites experienced identical transitions. For instance, at Lake Rutundu on Mt Kenya at the same elevation as Lake Mahoma, bamboo expansion preceded Afromontane forest growth, likely influenced by variations in fire. Variance partitioning indicates that each site responded differently to changes in temperature and rainfall. Therefore, these site-specific ecological responses underscore the importance of considering biogeographic legacies as management strategies are developed, despite similarities in modern ecology.

Determination of Optimal Soil Moisture Depletion Levels for Sweet Basil (Ocimum basilicum L.) at Wondo Genet, Ethiopia

Determining allowable soil moisture depletion level is critical for determining proper irrigation scheduling. The study was conducted at Wondo Genet Agricultural Research Center, Ethiopia, latitude 8°25'59'', longitude 39°01'44''and altitude of 1800 m.a.s.l to determine optimal soil moisture depletion level for sweet basil (Ocimum basilicum L.). Six levels of soil moisture depletion (20, 30, 40, 50, 60 and 100% of total available water (TAW) of the soil), with three replication were used as treatments to evaluate the yield and yield component of sweet basil in randomized complete block design. Different levels of soil moisture depletion levels significantly affected all recorded yield and yield components of sweet basil including its water productivity. Significantly higher yield and yield components were associated with frequently irrigated treatment under lower soil moisture depletion levels before irrigation. However, when sweet basil was irrigated beyond 40% TAW lowest yield and yield components were recorded. Therefore, sweet basil could be irrigated when the soil moisture content is depleted by 40% of the total available water content in the soil to enhance yield and water use efficiency in the study area and similar agro ecologies.

Pre-scaling up of Improved Tef Variety in Chora District of Buno Bedele Zone Southwestern Oromia, Ethiopia

Pre-scaling up of improved Dursi variety was carried out in Chora district of Buno Bedele zone Southwestern Ethiopia with the objectives to popularize improved Dursi tef variety, to create wider demand towards improved Dursi tef variety and strength stakeholders’ linkage in the study area. The variety was scaled up on ten farmers’ fields those predominantly selected in collaboration with respective three kebeles’ Development Agents based on farmers’ willingness to provide the required land size. The land size of 25 m x 25 m was used where all the recommended agronomic practice like seed rate, fertilizer rate and weed control method were used for the accomplishment of the activity. Training was provided to Dursi growers, development agents and woreda agricultural experts to facilitate further production and dissemination of the variety. Data like number of participants on the training and yield data were recorded and analyzed using simple descriptive statistics. The result revealed that, about 124 (104 male and 20 female) participants were participated on the training. The mean grain yield of 1790 kg ha-1 was obtained which is greater than yield obtained during demonstration trial. Therefore, Dursi variety was recommended for further dissemination across numerous tef producers in the study area and similar agro ecologies.

Applying 3D Models of Giant Salamanders to Explore Form-Function Relationships in Early Digit-Bearing Tetrapods.

Extant salamanders are used as modern analogs of early digit-bearing tetrapods due to general similarities in morphology and ecology, but the study species have been primarily terrestrial and relatively smaller when the earliest digit-bearing tetrapods were aquatic and an order of magnitude larger. Thus, we created a 3D computational model of underwater walking in extant Japanese giant salamanders (Andrias japonicus) using 3D photogrammetry and open-access graphics software (Blender) to broaden the range of testable hypotheses about the incipient stages of terrestrial locomotion. Our 3D model and software protocol represent the initial stages of an open-access pipeline that could serve as a "one-stop-shop" for studying locomotor function, from creating 3D models to analyzing the mechanics of locomotor gaits. While other pipelines generally require multiple software programs to accomplish the different steps in creating and analyzing computational models of locomotion, our protocol is built entirely within Blender and fully customizable with its Python scripting so users can devote more time to creating and analyzing models instead of navigating the learning curves of several software programs. The main value of our approach is that key kinematic variables (e.g. speed, stride length, and elbow flexion) can be easily altered on the 3D model, allowing scientists to test hypotheses about locomotor function and conduct manipulative experiments (e.g. lengthening bones) that are difficult to perform in vivo. The accurate 3D meshes (and animations) generated through photogrammetry also provide exciting opportunities to expand the abundance and diversity of 3D digital animals available for researchers, educators, artists, conservation biologists, etc. to maximize societal impacts.

Divergent visual ecology of Drosophila species drives object-tracking strategies matched to landscape sparsity

Maintaining stable gaze while tracking moving objects is commonplace across animal taxa, yet how diverse ecological needs impact these processes is poorly understood. During flight, the fruit-eating fly Drosophila melanogaster maintains course by making smooth steering adjustments to fixate the image of the distant visual background on the retina, while executing body saccades to investigate nearby objects such as food sources. Cactophilic Drosophila mojavensis live where there is no canopy; rather, the flora forming visual "background" and "objects" are one and the same. We tested whether D.mojavensis have adapted their flight control strategies for a visually sparse landscape. We used a magnetic tether that allows free movement in the yaw axis. In response to a textured bar moving across a similarly textured stationary background, D.melanogaster fixates the background, thereby stabilizing gaze while integrating bar dynamics to trigger tracking saccades. By contrast, two mojavensis subspecies in the repleta subgroup and one species in the melanogaster subgroup steer to smoothly fixate the bar, seemingly ignoring the stationary surround. Desert flies execute frequent bar-tracking saccades, but theirs are triggered when rotational velocity lags the bar. Thus, D.melanogaster, which lives in visually cluttered cosmopolitan habitats, leverages the optical disparities between nearby objects and distant foliage for a hybrid control strategy: "ground-fixate, object-saccade." Flies in distant phylogenetic subgroups with similar visual ecology use a "fixate-and-saccade" strategy, which would be adaptive in a visually sparse environment where individual landscape features are both approached and used to maintain a straight course.

Bycatch mitigation for commonly caught shark species in the Gulf of Mexico reef bottom longline fishery

AbstractObjectiveThe Gulf of Mexico (GOM) reef bottom longline fishery typically not only targets groupers and snappers but also interacts with 27 species of sharks, which are primarily discarded as bycatch. Slow growth, late maturity, and low fecundity in a landscape of increasing fishing pressure make sharks comparatively more susceptible to overfishing and endangered status than other fishes. The purpose of this study was to determine which gear and/or environmental variables best predict the shark catch per set for commonly caught shark species in the GOM reef bottom longline fishery.MethodsWe considered 12 commonly caught shark species that vary from the abundant Atlantic Sharpnose Shark Rhizoprionodon terraenovae to the critically endangered Scalloped Hammerhead Sphyrna lewini. Catch per set, effort, gear, and environmental data were taken from the National Oceanic and Atmospheric Administration National Marine Fisheries Service observer dataset for the GOM reef bottom longline fishery (2009–2017) and were used to fit generalized additive models. The Bayesian information criterion and 10‐fold cross‐validation were used to select the best set of variables that predicted catch per set to determine gear configurations, fisher activities, and environmental conditions contributing to higher shark catch per unit effort. We modeled each species individually, all species combined, and species grouped by similar ecology.ResultGear and fishing method variables were consistently included in the best predictive models across species and were the only potential basis for a single strategy that could decrease bycatch across all 12 species. Patterns of environmental variables were only consistent across species with similar ecology and habitat.ConclusionSharks as a group should not be lumped together, as the effects of mitigation measures become confounded and directly managing trade‐offs between species when minimizing bycatch becomes impossible. Focusing on gear rather than environmental variables is the best apparent option to potentially reduce shark catch per set across commonly caught species while minimizing trade‐offs.

Molecular Characterization, Evolution and Expression Analysis of Ammonium Transporter from Four Closely Related Bactrocera Species (Tephritidae).

Numerous insects are attracted to low levels of ammonia, utilizing it as a cue to locate food sources. The Ammonium Transporter (Amt), a highly conserved, atypical olfactory receptor, has been shown to mediate the detection of ammonia in insects. While the attraction of Tephritidae to ammonia is well established, knowledge about the Amt in this family is limited. The species Bactrocera dorsalis (Hendel 1912), Bactrocera cucurbitae (Coquillett 1899), Bactrocera correcta Bezzi 1916 and Bactrocera tau (Walker 1849), which are common agricultural pests within Tephritidae, exhibit numerous ecological similarities, offering a solid foundation for studying Amt characteristics in this family. In this study, we elucidated the sequences, evolutionary relationships, and expression patterns of Amt in these four species. The results indicated that these Amts share the same open reading frame, containing 1770 bp that encode a protein of 589 amino acid residues. These Amt proteins exhibit the typical structural characteristics of Amts, including an 11-transmembrane domain with an extracellular N-terminus and an intracellular C-terminus. They also have the ability to form trimers in the membrane. Additionally, they contain three conserved amino acid residues essential for ammonia transport: A189, H195, and H352. Phylogenetic and expression pattern analyses showed that they are highly conserved in Diptera and are significantly expressed in antennae. This study is the first report characterizing the Amt gene in four Tephritidae species. These findings provide a foundation for further exploration into the roles of these genes in their particular biological contexts.

Evaluation of Alternative Break Crops in Rotation with Bread Wheat (triticum aestivum l.) in South-Eastern Ethiopia

Crop rotation could be a possible intervention to resolve multifaceted problems of monoculture. In recent years, there is a concern about soil depletion caused by intensive farming. In crop rotation legume crops, which capture atmospheric nitrogen and “fix” it into forms available to plants will increase soil fertility. Faba bean (Vicia faba L.), rapeseed (Brassica napus L.), oat (Avena sativum L.) and vicia (Vicia dasycarpa Ten.) forage mixture were considered as a break/precursor crops. The result showed that most profitable cropping sequence was faba bean grown in a 3 year cycle with 2 crops of wheat (Amanuel et al., 1994). Thus, searching for promising and alternative break crops for wheat based rotation could increase productivity and maximize profit. Adaptaion trial around Bekoji showed that sweet lupine seems an option in tolerating acidity where faba bean is found susceptible. Thus, the objectives of this study was to evaluate alternative break crops on yield and yield components of the succeeding wheat and soil fertility maintenance in the rotation scheme. Thus, this study was executed for three consecutive years from 2017- 2019 main cropping seasons at Kulumsa, Bekoji and Asasa Arsi zone, South-Eastern Ethiopia to evaluate advantage of alternative break crops on yield and yield components of the succeeding wheat and its effect on soil fertility maintenance in the rotation scheme. The experiment was laid out in randomized block design with five replications. The treatment include: wheat-sweet lupine-wheat-wheatwheat in year one (2017), sweet lupine-wheat-wheat faba bean-Ethiopian mustard in year two (2018) and wheat-wheat-wheat-wheat-wheat in the third year (2019). These leguminous crops have improved physico-chemical properties of soil. Plant nutrients of soil on which legumes were grown were increased. This improvement of soil properties by leguminous crops has resulted in higher yield of wheat than plots on which wheat was grown after wheat. Although non-significant, the third year Bekoji and Asasa combined analysis of variance revealed that the highest wheat grain yield (4197kg/ha) was obtained at sweet lupine-wheat-wheat followed by wheat-faba bean-wheat (4003kg/ha). However, plant height was significantly (P<0.05) affected by rotational crops effect. The tallest plant height of wheat (105.0cm) was recoded from wheat-Ethioian mustard-wheat treatment. From this study, sweet lupine-wheat-wheat followed by wheat-faba bean-wheat with proper agronomic packages could be forwarded as a temporary recommendation in Asasa, Bokoji and Kulumsa areas and in areas with similar agro ecologies.

Phylogenetic proximity drives temporal succession of marine giant viruses in a five-year metagenomic time-series.

Nucleocytoplasmic Large DNA Viruses (NCLDVs, also called giant viruses) are widespread in marine systems and infect a broad range of microbial eukaryotes (protists). Recent biogeographic work has provided global snapshots of NCLDV diversity and community composition across the world's oceans, yet little information exists about the guiding 'rules' underpinning their community dynamics over time. We leveraged a five-year monthly metagenomic time-series to quantify the community composition of NCLDVs off the coast of Southern California and characterize these populations' temporal dynamics. NCLDVs were dominated by Algavirales (Phycodnaviruses, 59%) and Imitervirales (Mimiviruses, 36%). We identified clusters of NCLDVs with distinct classes of seasonal and non-seasonal temporal dynamics. Overall, NCLDV population abundances were often highly dynamic with a strong seasonal signal. The Imitervirales group had highest relative abundance in the more oligotrophic late summer and fall, while Algavirales did so in winter. Generally, closely related strains had similar temporal dynamics, suggesting that evolutionary history is a key driver of the temporal niche of marine NCLDVs. However, a few closely-related strains had drastically different seasonal dynamics, suggesting that while phylogenetic proximity often indicates ecological similarity, occasionally phenology can shift rapidly, possibly due to host-switching. Finally, we identified distinct functional content and possible host interactions of two major NCLDV orders-including connections of Imitervirales with primary producers like the diatom Chaetoceros and widespread marine grazers like Paraphysomonas and Spirotrichea ciliates. Together, our results reveal key insights on season-specific effect of phylogenetically distinct giant virus communities on marine protist metabolism, biogeochemical fluxes and carbon cycling.

Day-night gene expression reveals circadian gene disco as a candidate for diel-niche evolution in moths.

Temporal ecological niche partitioning is an underappreciated driver of speciation. While insects have long been models for circadian biology, the genes and circuits that allow adaptive changes in diel-niches remain poorly understood. We compared gene expression in closely related day- and night-active non-model wild silk moths, with otherwise similar ecologies. Using an ortholog-based pipeline to compare RNA-Seq patterns across two moth species, we find over 25 pairs of gene orthologs showing differential expression. Notably, the gene disco, involved in circadian control, optic lobe and clock neuron development in Drosophila, shows robust adult circadian mRNA cycling in moth heads. Disco is highly conserved in moths and has additional zinc-finger domains with specific nocturnal and diurnal mutations. We propose disco as a candidate gene for the diversification of temporal diel-niche in moths.

Barking up the wrong frog: global prevalence of misdirected amplexus in anuran amphibians

Abstract Reproduction is an energy-expensive life process in many organisms, and accurate conspecific recognition is crucial to successful reproduction. Nonetheless, misdirected attempts at amplexus towards heterospecifics appear to be common in many anuran amphibians. Such reproductive interference can have significant ecological and evolutionary consequences, but its prevalence remains unknown. Here, we compile a global dataset of anuran misdirected amplexus and test how phylogenetic relatedness, ecological niche, breeding phenology, and geography influence the prevalence of anuran misdirected amplexus. We find misdirected amplexus to be significantly higher among more closely related heterospecific pairs than between random pairs, but still occurred between species of different families. Misdirected amplexus was also significantly more common in arboreal and terrestrial anurans, and among species pairs with similar body sizes or with similar microhabitat use. We also show that misdirected amplexus is significantly more common among explosive breeders compared with prolonged breeders and is more prevalent in temperate regions compared with the tropics. Overall, we show that misdirected amplexus among anuran amphibians is not a rare phenomenon and that its prevalence is influenced by evolutionary relatedness, microhabitat use, ecological similarity, and breeding phenology. These interactions have the potential to cause species decline, hence understanding them is crucial.

Pseudanabaena pruinosa sp. nov. (Pseudanabaenales, Cyanobacteria): an Arctic Pseudanabaena species with branched sheaths and central aerotopes

ABSTRACT This study focused on polyphasic evaluation of four psychrophilic Pseudanabaena strains collected from extreme environments characterized by freezing temperatures. The strains were isolated from hydroterrestrial and terrestrial ecosystems in Petuniabukta Bay (Billefjorden, Svalbard), growing as icy microbial soil crusts. In addition to their unique ecology, the phylogenetic analyses of 16S rRNA revealed that the strains form a monophyletic clade within the Pseudanabaena sensu stricto cluster; this clade was unambiguously separated from the other Pseudanabaena infrageneric units, showing <98.5% 16S rRNA sequence identity with the other Pseudanabaena strains available in GenBank and possessing a unique and different D1 ITS region. Polyphasic evaluation of these four strains led to the description of the new species Pseudanabaena pruinosa sp. nov. which can be morphologically distinguished by light microscopy by several unique apomorphic traits not previously detected in Pseudanabaena. These traits include: production of widened, anastomotic branched sheaths enveloping several trichomes into a filament, heteropolar filaments with long trichomes with more than 20 cells, richly pseudobranched filaments forming tree-like structures, production of both polar and central aerotopes, and ability to produce swollen cells and to undergo irregular cell division. The characters observed for Pseudanabaena pruinosa, never reported for other species of Pseudanabaena, substantially widen the taxonomic concept of this genus. Therefore, the description of Pseudanabaena pruinosa sp. nov. with its unique ecology and distinct phylogenetic position and morphological features, is a significant addition to cyanobacteriology and represents a starting point for further research into the evolution of the genus Pseudanabaena. The new combination Pseudanabaena gygaxiana (Casamatta & Johansen) Aleksovski, Krstić & Strunecký is proposed based on16S rRNA, supported by its shared phenotypic traits and similar ecology to Pseudanabaena pruinosa.