Larger Individuals Research Articles

Naturalization of an alien ancient fruit tree at a fine scale: Community structure and population dynamics of Cydonia oblonga in China.

Naturalized plants play pivotal roles in local plant biodiversity and ecological functions; however, the drivers of naturalization remain poorly understood at a fine scale. Thus, understanding the processes of the development and dominance of alien plants in local natural habitats is of paramount importance. In the present study, we report for the first time the naturalization of Cydonia oblonga in China based on community structure and population dynamics at a fine scale. We conducted a comprehensive survey of the species through field community investigations, interviews, and a literature review. Cydonia oblonga is an ancient fruit tree with a long introduction history of over 4500 years worldwide and a cultivation history of over 2500 years in China. We analyzed C.oblonga community structure using the spatiotemporal substitution method and quantitatively analyzed population dynamics using a static life table, survivorship curve, and time series model to explore the naturalization processes. The following results were obtained. (i) The community comprised 31 coexisting vascular plant species (16 woody and 15 herbaceous species) belonging to 28 genera in 20 families. Rosaceae and Asteraceae were the two most dominant families. (ii) All individuals in the shrub layer as well as the C.oblonga population exhibited a roughly inverted J-shaped basal diameter distribution. A complete age structure was noted, and the survival curve was classified as Deevey type II. According to time series analysis, the population is estimated to increase in the future, specifically of medium and large individuals. (iii) Religious exchange, potent resource competitiveness, and similarity with the native habitat may be the major drivers of the introduction and successful naturalization of C.oblonga. These results suggest that alien species closely related to native ones are more likely to invade, naturalize, and dominate communities in local habitats.

Acoustic properties and shallow water propagation distances of Caribbean spiny lobster sounds (Panulirus argus)

Marine crustaceans produce broadband sounds that are useful for passive acoustic monitoring to support conservation and management efforts. However, the propagation characteristics and detection ranges of their signals are poorly known, limiting our leveraging of these sounds. Here, we used a four-hydrophone linear array to measure source levels (SLs) and sound propagation from Caribbean spiny lobsters (Panulirus argus) of a wide range of sizes within a natural, shallow water habitat (3.3 m depth). Source level in peak-peak (SLpp) varied with body size; larger individuals produced SLpp up to 166 dB re 1 μPa. However, transmission losses (TL) were similar across all sizes, with a global fitted TL of 12.1 dB. Correspondingly, calculated detection ranges varied with body size, ranging between 14 and 364 m for small and large individuals (respectively). This increased up to 1612 m for large spiny lobsters when considering lower ambient noise levels. Despite the potential ease of tank studies, our results highlight the importance of empirical in situ sound propagation studies for marine crustaceans. Given the important ecological and economic role of spiny lobsters, these data are a key step to supporting remote monitoring of this species for fisheries management and efforts to acoustically quantify coral reefs' health.

A Cloud Based Sentiment Analysis through Logistic Regression in AWS Platform

The use of Amazon Web Services is growing rapidly as more users are adopting the technology. It has various functionalities that can be used by large corporates and individuals as well. Sentiment analysis is used to build an intelligent system that can study the opinions of the people and help to classify those related emotions. In this research work, sentiment analysis is performed on the AWS Elastic Compute Cloud (EC2) through Twitter data. The data is managed to the EC2 by using elastic load balancing. The collected data is subjected to preprocessing approaches to clean the data, and then machine learning-based logistic regression is employed to categorize the sentiments into positive and negative sentiments. High accuracy of 94.17% is obtained through the proposed machine learning model which is higher than the other models that are developed using the existing algorithms.

Влияние пробиотика «Энзимспорин» на морфофизиологические показатели гибрида ленского осетра и белуги при выращивании в аквакультуре

The use of probiotics is recommended for sustainable growth, increased resistance and efficiency of feed assimilation. Currently, there are commercial probiotic products prepared from the bacteria Bacillus sp., Lactobacillus sp., Enterococcus sp., Carnobacterium sp. The use of the probiotic supplement “Enzimsporin” in fish farming is in its infancy. However, information is available on the effectiveness of its use in rainbow trout. In this regard, an urgent task is to study the effect of the probiotic “Enzimsporin” on the morphophysiological parameters of the juvenile hybrid of Lena sturgeon and beluga (Lenbel) under existing cultivation conditions. At the initial stage, the fish were divided into 8 groups of 50 fish each according to the principle of pairs of analogues. Large and small individuals were divided into four groups: control and experimental with a dose of Enzimsporin of 1 g/kg, 1.5 g /kg and 2 g/kg of feed, respectively. The duration of the experiment was 60 days. Total catches were made at the beginning and end of the experiment, and intermediate catches were made every 15 days, individually weighing 25–35% of the total number of fish in the pool. The physiological state and immune status of Lenbel were assessed by hematological and cytochemical parameters. Blood for analysis was collected from the caudal vein of fish in vivo. Leukocyte composition and the proportion of immature cell types were determined in Pappenheim-stained peripheral blood smears under a digital microscope. The phagocytic activity of fish neutrophils was evaluated by a lysosomal cation test using a cytochemical method with bromophenol blue. During the two months of the experiment, the main hydrochemical parameters (pH, nitrites, nitrates, ammonium), water temperature and the dissolved oxygen content were within the technological norms. The best absolute and relative growth rates were obtained in the experimental groups receiving a probiotic at a dose of 1.5 g/kg of feed. These fish had high indicators: absolute and relative growth, absolute and relative growth rate, mass accumulation coefficient. The best survival rate was recorded in the group of small yearlings of Lenbel at a probiotic dose of 2 g/kg of feed. In large fish, the maximum survival rate (80%) was recorded at a dose of 1 g/kg of “Enzimsporin”. There is significantly more lysosomal cationic protein in the blood neutrophils of the experimental groups – activation of cellular immunity.

Predicting Novatek Share Prices Using the Models of Decision Tree and Linear Regression

The development of technology and the emergence of various machine learning models influence social life in many ways, including the analysis and forecasting of the stock market. The ability to competently select and use machine learning models in predicting stock quotes is one of the key competitive advantages that allow large investment companies and individuals to increase their profits from the market activity. The study reveals the effectiveness of using decision tree and linear regression models in predicting daily quotes of NOVATEK.

How many species of tulips of the subgenus Orithyia (Tulipa, Liliaceae) are in Southern Siberia?

The subgenus Orithyia in the genus Tulipa is considered one of the least studied. It includes the most eastern species of tulips. Previously, three species of tulips from this subgenus, T. heteropetala, T. uniflora, and T. mongolica were reported for the territory of Southern Siberia. The morphological analysis showed that studied plants, from populations previously reported in Southern Siberia under the name T. heteropetala, are large individuals of T. uniflora. There was a high level of morphological differences between all populations of T. uniflora and T. mongolica. Karyotype analysis showed that T. mongolica, T. uniflora, and T. siniangensis have similar karyotype structures. In T. heterophylla, in comparison with them, a lower level of intrachromosomal asymmetry was noted. Molecular genetic analysis confirms previous data and separates the subgenus Orithyia among other subgenera in the genus Tulipa. Molecular data confirmed taxonomic affiliation of specimens from the Zabaykalsky Territory (Russia) previously assigned by morphological characters to T. mongolica. Thus, it was confirmed that two species of tulips of the subgenus Orithyia, Tulipa uniflora and T. mongolica, grow in the studied area.

Aseasonal and short life cycles of the protandrous hermaphrodite blue threadfin (Eleutheronema tetradactylum) in a near-equatorial tropical region

Context Eleutheronema tetradactylum is exploited throughout its distribution in the Indo–West Pacific region. However, there is a lack of data on its life cycle in near-equatorial regions and the northern hemisphere. Aim To investigate the age, growth, sex change and reproduction of Eleutheronema tetradactylum in southern Thailand. Methods Analysis of length, otolith and gonad data of 449 fish. Key results Contrary to findings from regions at higher latitudes, otoliths did not show seasonal increment formation. Instead, with the exception of large individuals, daily increments were distinguishable. Within the age range of 69–341 days, growth was linear, with results indicating a total length of 430 mm (69% of maximum length) at 1 year. The youngest mature male was 137 days old. Moreover, the length at which half the individuals changed from male to female was 376 mm, corresponding to 282 days. The gonadosomatic index indicated no specific spawning season, and the hatch-date calculations indicated year-round hatching. Conclusions Eleutheronema tetradactylum inhabiting near-equatorial regions is characterised by rapid population turnover compared with populations of higher latitudes. Implications Our findings indicated life-history variability, including seasonality loss in near-equatorial habitats, of an important coastal fish. This information is important for species conservation.

Size-Mediated Sea Turtle Behavioral Responses at Artificial Habitats in the Northern Gulf of Mexico.

Our understanding of size-specific sea turtle behavior has lagged due to methodological limitations. However, stereo-video cameras (SVC) are an in-water approach that can link body-size and allow for relatively undisturbed behavioral observations. In this study, we conducted SVC dive surveys at local artificial reefs, piers, and jetties in the northern Gulf of Mexico (nGOM) from May 2019 to August 2021. Using SVCs, we measured sea turtle straight carapace length, documented behaviors, and quantified wariness by assessing minimum approach distance (MAD). In green sea turtles (Chelonia mydas), the observed MAD ranged from 0.72 to 5.99 m (mean 2.10 m ± 1.10 standard deviation (SD), n = 73). For loggerhead sea turtles (Caretta caretta), the MAD ranged between 0.93 and 3.80 m (mean 2.12 m ± 0.99 SD, n = 16). Kemp's ridley sea turtles (Lepidochelys kempii) were similar to loggerheads, and MAD ranged from 0.78 to 3.63 m (mean 2.35 m ± 0.99 SD, n = 8). We then evaluated what biological factors could impact the MAD observed by species, but we excluded Kemp's ridleys as the sample size was small. Using a linear mixed model and model selection based on AICc, the top ranked model for both green and loggerhead sea turtles included SCL as the most important factor influencing MAD. MAD did not vary with habitat type for either species. Our results showed that larger individuals, regardless of species, have a greater wariness response, becoming startled at greater distances than smaller individuals. The findings of our study support the use of SVC as an accessible, non-invasive tool to conduct ecologically relevant in-water surveys of sea turtles to link behavioral observations to body size.

Development and interaction of ctenophores <i>Beroe ovate</i> Bruguière, 1789 and <i>Mnemiopsis leidyi</i> A. Agassiz, 1865 in the coastal zone of the Middle Caspian Sea

Aim. Analysis of the distribution and status of ctenophores Вeroe ovata and Mnemiopsis leidyi, and assessment of the parameters of their interaction in the Middle Caspian Sea.Material and Methods. The material was obtained in the western and eastern parts of the Middle Caspian Sea in September–October 2022. Large ctenophores were collected using a big cone plankton net with a 0.5 m2 opening and a 500 μm, mesh size. The number and size of large ctenophores were determined immediately after collection, larvae and eggs were counted in samples fixed with formalin to a final concentration of 4%. Zooplankton samples were collected by the Juday plankton net (0.1 m2 opening, 180 μm mesh size).Results. In September‐October 2022, a developed population of Вeroe ovata with active reproduction was recorded in the waters of the Middle Caspian Sea. The habitat area of B. ovata has significantly expanded to the north compared to 2021. Complete suppression of the Mnemiopsis population by the Beroe was observed on most of the western and eastern shelf, as well. The total number of Beroe reached 48 ind/m2, biomass – 12 g/m2. Single large individuals were found in the north of the Middle Caspian Sea at salinity 5.7 psu. The structure of mesozooplankton was still dominated by the small copepod Acartia tonsa.Conclusion. New data indicate the active development of the Вeroe ovata in the Caspian Sea, which presents a fundamental challenge for the restoration of the Caspian ecosystem. The progressive adaptation of Beroe to the conditions of the Caspian Sea has led to its expansion to the north of the Middle Caspian Sea in areas with low salinity. A complete suppression of the M. Leidyi population by the new alien noted on most of the shelf indicates an increase in its pressure on the Mnemiopsis population compared to the corresponding period of 2021.

Amendment of a thermophile-fermented compost to humus improves the growth of female larvae of the Hercules beetle Dynastes hercules (Coleoptera: scarabaeidae).

Hercules beetle is a popular pet and large adult individuals are considered valuable. Incorporating compost prepared from marine animals and fermented by thermophilic bacteria into the humus benefits the gut microflora of several livestock. Here, we evaluated whether this compost improves the growth of the Hercules beetle (Dynastes hercules hercules) larvae. We mixed the compost grains with the humus at a final concentration of 1% (w/w) and transferred ∼90 days old Hercules beetle larvae to fresh humus with or without the compost. After 72 days rearing period, only the female larvae reared in the humus with compost exhibited superior growth, compared with those grown in compost-free humus. The gut bacterial composition was determined at 0 and 46 day after transferring the larvae to humus with or without compost. Improved growth of the female larvae was associated with increased abundance of Mollicutes and decreased abundance of Gammaproteobacteria. The thermophile-fermented compost has a probiotic effect on the female Hercules beetle larvae that is mediated by altered gut microflora.

Does ontogeny matter for the spring temperature requirement for bud burst of two coniferous species in cool temperate forests?

Spring leaf phenology is an important event for trees to determine carbon fixation during the growing season. However, less is understood about the intraspecific variation in spring leaf phenology and its relationship with the spring temperature requirements of conifers, which is problematic for accurately predicting the influence of spring climate warming on conifers. I monitored bud burst timing and the degree days required for bud burst for seedlings and large individuals of Abies sachalinensis (fir) and Larix kaempferi (larch) over two seasons in northern Japan. Contrary to my expectation, the degree days required for the bud burst of small individuals were similar to or larger than those of the large individuals for fir and larch. Consequently, the bud burst timing of small individuals was similar to or later than that of large individuals for fir and larch. Even when conifer species are in their early stage, the spring temperature requirement for bud burst is not necessarily less than that for large individuals, which is not the case for many broad-leaved species. These results indicate that for these two coniferous species, ontogenetic differences in temperature requirements are not necessary to be considered for the response of communities to spring climate change.

Limited effects of size-selective harvesting and harvesting-induced life-history changes on the temporal variability of biomass dynamics in complex food webs

Harvesting has been implicated in destabilizing the abundances of exploited populations. Because selective harvesting often targets large individuals, some studies have proposed that exploited populations often experience demographic shifts toward younger, smaller individuals and become more sensitive to environmental fluctuations. The theory of consumer–resource dynamics has been applied to address the impacts of harvesting in simple modular food webs, but harvested populations are embedded in a complex food web in nature. In addition, exploited populations have been shown to undergo trait evolution or phenotypic changes toward early maturation at smaller sizes. Using an empirically derived complex food web model, Kuparinen et al. (2016. Fishing-induced life-history changes degrade and destabilize harvested ecosystems. Scientific Reports: 6, 22,245) demonstrated that exploited fish populations and other ecosystem properties increased variability due to harvesting and harvesting-induced life-history evolution in the absence of environmental fluctuations. In the present study, we examined a large set of simulated complex food webs to attest the generality of the findings in Kuparinen et al. (2016). We found that harvesting both increased and decreased temporal variability of fish biomass dynamics, especially in food webs with intrinsically oscillating dynamics, while the vast majority of the food webs did not experience destabilization. We also elucidated the large impacts of the shape of functional responses on food web structure, energy flow, and changes in temporal variability caused by harvesting. Our results suggest that the destabilizing or stabilizing effects of harvesting and harvesting-induced evolution importantly depend on the shape of functional responses in dynamical models of complex food webs and that food webs with intrinsically oscillating dynamics are more prone to changes in temporal variability caused by harvesting and harvesting-induced evolution.

Invasion of rocky shores by a mytilid mussel reveals an abundant‐centre distribution coupled with moderate increases in densities at its absolute range limits

AbstractSemimytilus patagonicus is an invasive mussel on the coast of southern Africa and has extended its range in recent years. We asked whether its distribution and abundance are consistent with the abundant‐centre hypothesis (ACH). Marginal populations were located by monitoring 33 rocky shore sites in South Africa and southern Namibia in 2021. This revealed no changes to its distributional limits since 2020. At nine of these sites, population demography was measured to allow a comparison of their densities and size structure. Four were central populations on the west coast of South Africa (including the site where the species was first detected in 2009). Four were marginal populations in South Africa: two towards the cold range edge in the north and two towards the warm range edge to the south. The ninth population was in southern Namibia, representing a recent invasion event first detected in 2014. Across the species' South African range, the distribution of its abundance was generally consistent with the ACH, with the greatest abundance at its range centre and a gradual decrease towards the range edges. However, the ultimate marginal population at both its cold and warm range edges showed moderate upticks in abundance compared to the penultimate marginal populations. Additionally, marginal populations in South Africa typically included a greater proportion of large individuals. Recruitment intensity was greater in warm range edge populations than cold range edge populations. The size structure of the population in Namibia resembled those of central populations in South Africa. Moderate increases in densities at the absolute range limits suggest that the species is currently undergoing spread into regions associated with moderately optimal environmental conditions (ultimate range edge sites) after encountering regions associated with suboptimal environmental conditions (penultimate range edge sites).

Acoustic scaling in the European spiny lobster (Palinurus elephas).

Sound is an important cue for arthropods. In insects, sound features and sound-producing apparatus are tightly correlated to enhance signal emission in larger individuals. In contrast, acoustic scaling in marine arthropods is poorly described even if they possess similar sound-producing apparatus. Here, the acoustic scaling of the European spiny lobster is analyzed by recording sounds in situ at 1 m from a wide range of body sizes. The dimensions of associated sound-producing apparatus increased with body size, indicating sound features would also be influenced by spiny lobster size. Indeed, temporal sound features changed with body size, suggesting differences in calling songs could be used for spiny lobster acoustic communication. Source levels (peak-peak) ranged from 131 to 164 dB re 1μPa for smaller and larger lobsters, respectively, which could be explained by more efficient resonating structures in larger animals. In addition, dominant frequencies were highly constrained by ambient noise levels, masking the low-frequency content of low intensity sounds from smaller spiny lobsters. Although the ecological function of spiny lobster sounds is not clear yet, these results suggest larger body sizes benefit because louder calls increase the broadcast area and potential interactions with conspecifics, as shown in the insect bioacoustic literature.

Grouping behavior in a Triassic marine apex predator

Marine tetrapods occupy important roles in modern marine ecosystems and often gather in large aggregations driven by patchy prey distribution,1,2 social or reproductive behaviors,3,4 or oceanographic factors.5 Here, we show that similar grouping behaviors evolved in an early marine tetrapod lineage, documented by dozens of specimens of the giant ichthyosaur Shonisaurus in the Luning Formation in West Union Canyon, Nevada, USA.6,7 A concentration of at least seven skeletons closely preserved on a single bedding plane received the bulk of previous attention. However, many more specimens are preserved across ∼106 square meters and ∼200 stratigraphic meters of outcrop representing an estimated >105-6 years. Unlike other marine-tetrapod-rich deposits, this assemblage is essentially monotaxic; other vertebrate fossils are exceptionally scarce. Large individuals are disproportionately abundant, with the exception of multiple neonatal or embryonic specimens, indicating an unusual demographic composition apparently lacking intermediate-sized juveniles or subadults. Combined with geological evidence, our data suggest that dense aggregations of Shonisaurus inhabited this moderately deep, low-diversity, tropical marine environment for millennia during the latest Carnian Stage of the Late Triassic Period (237-227 Ma). Thus, philopatric grouping behavior in marine tetrapods, potentially linked to reproductive activity, has an antiquity of at least 230 million years.

DISTRIBUTION PATTERNS OF METACERCARIAE OF THE TREMATODA <i>APOPHALLUS </i><i>MUEHLINGI</i> (JÄGERSKIÖLD, 1899) IN UNDERYEARLINGS IN AN INVASIVE POPULATION OF <i>CLUPEONELLA CULTRIVENTRIS</i> (NORDMANN, 1840) FROM THE GORKY RESERVOIR (UPPER VOLGA BASIN)

After the successful naturalization of the prosobranch mollusk Lithoglyphus naticoides (C. Pfeiffer, 1828) and a number of associated trematodes in the Gorky Reservoir (in 2005-2015) an intensive spread of apophallesis in fish of this water body has been observed. As one of the second intermediate hosts of the trematode causing this disease, Apophallus muehlingi (Jägerskiöld, 1899), a freshwater form of the Black Sea-Caspian kilka Clupeonella cultriventris (Nordmann, 1840) was recorded. The aim of the work is to study the consequences of dispersal of C. cultriventris for the formation of large permanent foci of apophallesis in the Upper Volga. For comparison, data on the spread of this type of "black-spot" disease in the populations of C. cultriventris from the Gorky Reservoir and an unregulated area of the Lower Volga (downstream the cascade of Volga reservoirs, pelagic trawl coordinates from 47°08ʹN, 47°17ʹE to 46°51ʹN, 47°41ʹE) were used. The high rates of occurrence of A. muehlingi metacercariae (the infection prevalence P, %) are recorded in the fall along the entire area of the Gorky Reservoir: from the northernmost site near Rybinsk (58°01ʹN, 39°06ʹE) to the dam area (56°41ʹN, 43°21ʹE). It is found that the distribution pattern of A. muehling metacercariae varies in the sections of the reservoir differing in hydrological characteristics. In the middle (transitional type) section of the reservoir the prevalence of A. muehlingi metacercariae in groups of the smallest Black Sea-Caspian kilka fingerlings (with a body length of up to 45 mm), is close to the maximally possible (30.00-94.49%). In the upper (river-type) section of the reservoir, the prevalence of metacercariae in this group of fish does not exceed 24.39%. The minimum values of this indicator are found in the lower (lake-type) section of the reservoir (6.76-14.84%). Judging by the values of the abundance index and the coefficient of variation in the infection intensity, the aggregation of metacercariae is more pronounced in the groups of faster growing underyearlings and the Black Sea-Caspian kilka yearlings as compared to the groups of the smallest fingerlings. In the Black Sea-Caspian kilka fingerlings samples from the Lower Volga in 2020 reveals no statistically significant differences between the infection prevalence values (13.33-18.11%) in the different size groups. Thus, although the main second intermediate hosts of A. muehlingi are various fish species of the Cyprinidae family, in some cases the presence of C. cultriventris in the water body ecosystem can significantly increase the likelihood of apophallesis spread. In conditions of the Upper Volga, due to the high migration activity of large individuals of the Black Sea-Caspian kilka, a continuous zone of apophallesis can form without clearly defined boundaries between the individual foci of disease.

Can an invader support commercial fishing? A case study of walleye pollock Gadus chalcogrammus in the western Chukchi Sea

Based on research of bottom and mid-water trawl surveys conducted onboard Russian research vessels in 2003–2020, data on the spatial and vertical distributions of walleye pollock Gadus chalcogrammus in the western Chukchi Sea are presented. The response of walleye pollock distribution related to water temperature, as well as the features of its distribution are also presented. In the water column, schools were mainly comprised of juveniles, while medium-sized and large individuals were scarce. Approximately 98% of the total number of juveniles and 100% of the large pollock caught by bottom trawls were observed in the southern part of the study area, while most of medium-sized fish were found in the northern part. In the water column, walleye pollock was found within the upper 65 m layer. Near the bottom, the majority of small-sized fish and all large individuals were observed at depths shallower 100 m, while over 70% of medium-sized walleye pollock were found at depths than 100 m. In the water column, juveniles were observed at temperatures from −0.4 to 3.3 °C with largest concentrations within a temperature ranges of 0.9–1.8 °C) and 3.0 °C. Near the bottom, walleye pollock were recorded at a temperature from −1.2 to 4.3 °C with maximum number within the ranges 2–3 °C, > 3 °C, and 1–2 °C. A few individuals were found at bottom temperatures below 0 °C. In the water column, the abundance was low during the entire study period. Acoustic estimates were notably higher compared to those based on the results of bottom trawl surveys. The recent dramatic increase of walleye pollock abundance in the western Chukchi Sea appears to reflect a complex of factors, including warming of bottom temperatures, decreasing of ice cover, increasing of northward currents, better foraging conditions, and increasing abundance and biomass in the Bering Sea. An attempt is made to determine the prospects for commercial fishing of walleye pollock in the western Chukchi Sea. Bottom trawl surveys in 2019–2020 indicated an estimate of total allowable catch of 37,200 t for the 2021 and 2022 fishing seasons; in 2021 over 4000 t were caught. However, this kind of fishing cannot be considered sustainable due to several reasons, including the inability to forecast the number of fish migrating from the Bering Sea, the limited fishing season due to harsh climatic conditions, the remoteness of main ports, and the uncertain population status of its stocks.

Differences in the Morphology and Reproduction of the Ascidian Boltenia Villosa Across a Latitudinal Gradient

While the larval and early juvenile stages of the stalked ascidian Boltenia villosa are well-documented in the literature, little is known about the range of morphological variation in B. villosa adults. Anecdotal evidence suggests that larger individuals with shorter stalks make up the populations found in Washington, while Oregon populations consist of smaller individuals with longer stalks. The present study aimed to develop a qualitative understanding of the morphological and reproductive differences across the latitudinal gradient of B. villosa. Morphological differences between populations were studied through a combination of morphometrics and scanning electron microscopy. To compare reproductive outputs, the diameters of oocytes and the gonadosomatic indices of representative individuals were measured. The results suggest significant differences between the two populations in body proportions, spine character, and reproduction despite their genetic similarities. These preliminary results provide the basis for future research into the distribution of B.villosa and the possible existence of an undescribed subspecies of B. villosa.

Metabolic rate and climate change across latitudes: evidence of mass-dependent responses in aquatic amphipods.

Predictions of individual responses to climate change are often based on the assumption that temperature affects the metabolism of individuals independently of their body mass. However, empirical evidence indicates that interactive effects exist. Here, we investigated the response of individual standard metabolic rate (SMR) to annual temperature range and forecasted temperature rises of 0.6-1.2°C above the current maxima, under the conservative climate change scenario IPCC RCP2.6. As a model organism, we used the amphipod Gammarus insensibilis, collected across latitudes along the western coast of the Adriatic Sea down to the southernmost limit of the species' distributional range, with individuals varying in body mass (0.4-13.57 mg). Overall, we found that the effect of temperature on SMR is mass dependent. Within the annual temperature range, the mass-specific SMR of small/young individuals increased with temperature at a greater rate (activation energy: E=0.48 eV) than large/old individuals (E=0.29 eV), with a higher metabolic level for high-latitude than low-latitude populations. However, under the forecasted climate conditions, the mass-specific SMR of large individuals responded differently across latitudes. Unlike the higher-latitude population, whose mass-specific SMR increased in response to the forecasted climate change across all size classes, in the lower-latitude populations, this increase was not seen in large individuals. The larger/older conspecifics at lower latitudes could therefore be the first to experience the negative impacts of warming on metabolism-related processes. Although the ecological collapse of such a basic trophic level (aquatic amphipods) owing to climate change would have profound consequences for population ecology, the risk is significantly mitigated by phenotypic and genotypic adaptation.

Allometric scaling improves the characterization of complex community transcriptomes.

Allometric scaling, that is scaling patterns in physiological processes relative to body size, can be used to overcome the current limitations in metatranscriptomics. Metatranscriptomics refers to the use of RNA transcripts to characterize a complex community. In contrast to metagenomics, metatranscriptomics allows one to simultaneously address community composition and functionality through the characterization of the community transcriptome. Hence, insights into metabolic processes and molecular pathways can also be obtained. Despite its increasing use in community ecology, a major limitation and source of error is the variation in RNA transcript abundance across organisms varying in body size. Hence, this may lead to incorrect estimations of the community structure and functioning as larger RNA quantities from larger individuals may overestimate their community contribution.