High Fecundity Research Articles

Analysis of Elimination Effects of Inbreeding on Genotype Frequency in Larval Stages of Chinese Shrimp.

Marine animals possess genomes of considerable complexity and heterozygosity. Their unique reproductive system, characterized by high fecundity and substantial early mortality rates, increases the risk of inbreeding, potentially leading to severe inbreeding depression during various larval developmental stages. In this study, we established a set of inbred families of Fenneropenaeus chinensis, with an inbreeding coefficient of 0.25, and investigated elimination patterns and the manifestations of inbreeding depression during major larval developmental stages. Reduced-representation genome sequencing was utilized to explore the genotype frequency characteristics across two typical elimination stages. The results revealed notable mortality in hatching and metamorphosis into mysis and post-larvae stages. Inbreeding depression was also evident during these developmental stages, with depression rates of 24.36%, 29.23%, and 45.28%. Segregation analysis of SNPs indicated an important role of gametic selection before hatching, accounting for 45.95% of deviation in the zoea stage. During the zygotic selection phase of larval development, homozygote deficiency and heterozygote excess were the main selection types. Summation of the two types explained 82.31% and 89.91% of zygotic selection in the mysis and post-larvae stage, respectively. The overall distortion ratio decreased from 22.37% to 12.86% in the late developmental stage. A total of 783 loci were identified through selective sweep analysis. We also found the types of distortion at the same locus could change after the post-larvae stage. The predominant shifts included a transition of gametic selection toward normal segregation and other forms of distortion to heterozygous excess. This may be attributed to high-intensity selection on deleterious alleles and genetic hitchhiking effects. Following larval elimination, a greater proportion of heterozygous individuals were preserved. We detected an increase in genetic diversity parameters such as expected heterozygosity, observed heterozygosity, and polymorphic information content in the post-larvae stage. These findings suggest the presence of numerous recessive deleterious alleles and their linkage and suggest a major role of the partial dominance hypothesis. The results provide valuable insights into the mechanisms of inbreeding depression in marine animals and offer guidance for formulating breeding strategies in shrimp populations.

Whole-Genome Sequencing Analyses Reveal the Evolution Mechanisms of Typical Biological Features of Decapterus maruadsi.

Decapterus maruadsi is a typical representative of small pelagic fish characterized by fast growth rate, small body size, and high fecundity. It is a high-quality marine commercial fish with high nutritional value. However, the underlying genetics and genomics research focused on D. maruadsi is not comprehensive. Herein, a high-quality chromosome-level genome of a male D. maruadsi was assembled. The assembled genome length was 716.13 Mb with contig N50 of 19.70 Mb. Notably, we successfully anchored 95.73% contig sequences into 23 chromosomes with a total length of 685.54 Mb and a scaffold N50 of 30.77 Mb. A total of 22,716 protein-coding genes, 274.90 Mb repeat sequences, and 10,060 ncRNAs were predicted, among which 22,037 (97%) genes were successfully functionally annotated. The comparative genome analysis identified 459 unique, 73 expanded, and 52 contracted gene families. Moreover, 2804 genes were identified as candidates for positive selection, of which some that were related to the growth and development of bone, muscle, cardioid, and ovaries, such as some members of the TGF-β superfamily, were likely involved in the evolution of typical biological features in D. maruadsi. The study provides an accurate and complete chromosome-level reference genome for further genetic conservation, genomic-assisted breeding, and adaptive evolution research for D. maruadsi.

Comparison of the effect of tea shoots during different seasons in Arma chinensis (Hemiptera: Pentatomidae) reared on Ectropis grisescens (Lepidoptera: Geometridae) pupae.

In this study, we compared the growth, development, and fecundity of Arma chinensis (Fallou) reared on pupae of the geometrid Ectropis grisescens Warren fed on tea shoots during different seasons of the year. The raw data on life history were analyzed using the age-stage, 2-sex life table. When reared on spring or winter geometrid pupae, the duration of the immature stage of A. chinensis was significantly longer than in those produced during the summer or autumn. The survival rate of immature A. chinensis reared on autumn geometrid pupae was significantly lower compared to other treatments. Reproductive diapause was observed in adult A. chinensis reared on winter geometrid pupae. The adult preoviposition period (APOP), total preoviposition period (TPOP), and total longevity were significantly longer in A. chinensis reared on winter pupae than in the other treatments. The fecundity of A. chinensis reared on spring geometrid pupae was significantly lower than in the other treatments. The higher intrinsic rate of increase of the A. chinensis reared on summer pupae (r = 0.0966 day-1) and autumn pupae (r = 0.0983 day-1) resulted in higher fecundity, shorter immature duration, and shorter TPOP compared to the winter and spring populations. These findings can be utilized to enhance and sustain biological control of E. grisescens in tea plantations.

Association analysis of polymorphisms in SLK, ARHGEF9, WWC2, GAB3, and FSHR genes with reproductive traits in different sheep breeds.

The aim was to investigate the relationship between polymorphisms of gene mutation loci and reproductive traits in local sheep breeds (Duolang Sheep) and introduced sheep breeds (Suffolk, Hu Sheep) in Xinjiang to provide new molecular markers for the selection and breeding of high fecundity sheep. The expression pattern of typing successful genes in sheep tissues was investigated by RT-qPCR technology, providing primary data for subsequent verification of gene function. The 26 mutation loci of WWC2, ARHGEF9, SLK, GAB3, and FSHR genes were typed using KASP. Association analyses were performed using SPSS 25.0, and the typing results showed that five genes with six loci, WWC2 (g.14962207 C>T), ARHGEF9 (g.48271079 C>A), SLK (g.27107842 T>C, g.27108855 G>A), GAB3 (g.86134602 G>A), and FSHR (g.80789180 T>G) were successfully typed. The results of the association analyses showed that WWC2 (g.14962207 C>T), SLK (g.27108855 G>A), ARHGEF9 (g.48271079 C>A), and FSHR (g.80789180 T>G) caused significant or extremely significant effects on the litter size in Duolang, Suffolk and Hu Sheep populations. The expression distribution pattern of the five genes in 12 sheep reproduction-related tissues was examined by RT-qPCR. The results showed that the expression of the SLK gene in the uterus, the FSHR gene in the ovary, and the ARHGEF9 gene in hypothalamic-pituitary-gonadal axis-related tissues were significantly higher than in the tissues of other parts of the sheep. WWC2 and GAB3 genes were highly expressed both in reproductive organs and visceral tissues. In summary, the WWC2 (g.14962207 C>T), SLK (g.27108855 G>A), ARHGEF9 (g.48271079 C>A), and FSHR (g.80789180 T>G) loci can be used as potential molecular markers for detecting differences in reproductive performance in sheep. Due to variations in typing results, the SLK (g.27107842 T>C) and GAB3 (g.86134602 G>A) loci need further validation.

Life-history of masked water snakes (Homalopsis buccata) in Java: implications for the sustainability of harvesting

Context Masked water snakes (Homalopsis buccata, Homalopsidae) thrive in the muddy edges of agricultural ponds and canals in densely populated areas of West Java, Indonesia, and are harvested by local farmers to protect fish stocks and to provide meat, skins, and medicines for commercial use. Aims Here, we aimed to quantify sexual dimorphism and reproductive biology of H. buccata, so as to deepen our knowledge of the species’ inherent ability to withstand commercial harvests. Methods We examined carcasses of 4286 snakes at six processing sites to quantify biological attributes (e.g. sexual dimorphism in body size and shape, seasonality of reproduction, fecundity, reproductive frequency), with emphasis on traits that affect the ability of snake populations to withstand this intensive harvesting. Key results The snakes we examined were primarily adults (<1% juvenile), with approximately equal numbers of males and females except in January (when females comprised >90% of specimens). Females grow larger than males, and they are more heavy-bodied but shorter-tailed than are males of the same snout–vent length. Reproduction is seasonal in both sexes, with testis volumes decreasing to a minimum over the period August to November (late dry season) when most adult-size females were gravid. Litter sizes ranged from 1 to 37 (mean 12), increasing with maternal body size, with ~75% of females reproducing each year. Conclusions On the basis of these results, we infer that the life history of H. buccata (viviparity, high fecundity, frequent reproduction, rapid maturation) renders it inherently resilient to harvesting, especially because that offtake is based on males as well as females. Because a lack of sustainability is evident only in hindsight, regular monitoring of the trade could assure that any problems are detected rapidly. Implications To further buffer these populations from the impact of harvest, hunting could be restricted during January (a time when gravid females are disproportionately vulnerable) and the largest snakes (females, with high fecundity and reproductive frequency) could be excluded from harvests.

Diet and body size modulate the remating behaviour of a predaceous ladybird, Coccinella transversalis (Fabricius) (Coleoptera, Coccinellidae)

The nutritional condition and body size influence the mating and female remating behaviour of a predaceous ladybird, Coccinella transversalis. When well-fed males were provided with females of three different dietary conditions, viz. (i) well-fed, (ii) food-deprived and (iii) honey-fed, the well-fed ones were most fecund with highest percentage of egg-viability and least preoviposition period and remating refusals, while food-deprived ones showed vice-versa. However, honey-fed females laid unfertile eggs after coercively mating with males, and resisted the most to remate, which gets strengthened in the second mating trial. This indicates females’ nutritional condition modulates the females’ mating behaviour and post-mating outcomes. The adult body size was directly proportional to reproductive output with heavier females showing high fecundity and percentage of egg viability with least preoviposition period than the lighter ones. Large females resisted the least to remate with larger males than with smaller males, while large males coercively mated with smaller females. Regardless of body-size, the females’ remating resistance was enhanced in the second mating trial. Both diet and adult body size modulate the re-mating behaviour of female C. transversalis, as the food-deprived and large females greatly resisted to re-mate with smaller males.

Enhancement of aquaculture performance of cobia, Rachycentron canadum (Linnaeus 1766): A review

Cobia, Rachycentron canadum, is a marine fish with recognized potential for aquaculture due to its fast growth rate, high fecundity, disease resistance, and quality flesh. However, much progress has been made to overcome problems associated with aspects of cobia production, including broodstock management, fingerling production, larval-rearing, grow-out, and disease management, though, an effort is needed to ensure its sustainability. Broodstock conditioning protocols for continuous spawning as well as induced spawning via hormonal injection resulted in all-year-round seed production in cobia, but detailed information on the cost-effective dosages of various spawning hormones for maximum fecundity and larval survival needs to be investigated. Selective breeding, the application of genetics in trait selection, and the use of molecular markers could produce more viable strains to mitigate high mortality, particularly in colder climates. In addition, considering the fact cobia are carnivorous fish with a high protein requirement, it will be necessary to investigate fishmeal alternatives to reduce feeding costs. Low salinity pond culture may become a reality in the future if the cobia metabolism-physiology of nutrition at various levels of salinity is well understood. The present paper provides information on some of the options for optimizing the aquaculture performance of Rachycentron canadum.

Почвенная нематода Caenorhabditis elegans как модель для изучения паразитических нематод

The free-living soil nematode Caenorhabditis elegans has been used as model organism in biological researches since middle of the 1960th. The short lifecycle, small body size, high fecundity, simplicity and cheapness of cultivation in laboratory, and safety for researchers are advantages of C. elegans as experimental model to study biology of Metazoa. The discussion about the possibility to use C. elegans as the model for parasitic nematodes started with the first mention of this nematode in scientific literature. The present article is the review of experimental studies demonstrating that in many cases substances toxic for C. elegans are also toxic for parasitic nematodes, and vice versa. This allows making a conclusion about the prospectivity to use C. elegans for initial screening for substances with nematicidal activity followed by their testing in experiments with parasitic nematodes. The possibility to use C. elegans for understanding mechanisms of nematicides action is also indisputable. On the whole one may conclude that C. elegans is a useful model both for searching new substances with anthelmintic activity and solution of the problem to overcome drug resistance of helmints.

TEMPERATURE AND PHOTOPERIOD EFFECT ON DURATION OF GONOTROPHIC DEVELOPMENT AND FECUNDITY OF A LABORATORY COLONY OF AEDES ALBOPICTUS

The impact of temperature and photoperiod on duration of gonotrophic development and fecundity in a Gainesville strain of Aedes albopictus Skuse were observed in laboratory settings. Photoperiodic regimens at 24L:0D, 14L:10D, 12L:12D, 8L:16D, and 0L:24D were tested on females reared at 25° C. A series of temperatures 15° C, 20° C, 25° C, 30° C, and 33º C were tested on females reared at 16L:8D. The gonotrophic development duration showed a significant difference only between 8L:16D and 0L:24D which had the longest and shortest cycles, respectively. Fecundity was highest at 14L:10D and lowest at 0L:24D without significant differences between different photoperiodic regimens. Both 1st and 2nd gonotrophic cycle durations differed significantly only between 15° C/ 20° C and 33º C which had the longest and shortest cycles, respectively. The highest temperature had the highest fecundity in the 1st gonotrophic cycle whereas it had the lowest fecundity in the 2nd cycle. The findings of this study would benefit in estimating field Ae. albopictus population for control and for rearing purposes.Aedes albopictus

Zebrafish as a Model for Cardiovascular and Metabolic Disease: The Future of Precision Medicine.

The zebrafish (Danio rerio) has emerged as an appreciated and versatile model organism for studying cardiovascular and metabolic diseases, offering unique advantages for both basic research and drug discovery. The genetic conservation between zebrafish and humans and their high fecundity and transparent embryos allow for efficient large-scale genetic and drug-oriented screening studies. Zebrafish possess a simplified cardiovascular system that shares similarities with mammals, making them particularly suitable for modeling various aspects of heart development, function, and disease. The transparency of zebrafish embryos enables the real-time visualization of cardiovascular dynamics, offering insights into early embryonic events and facilitating the study of heart-related anomalies. In metabolic research, zebrafish provide a cost-effective platform for modeling obesity, type 2 diabetes, hyperlipidemia, and other metabolic disorders. Their high reproductive rate allows for the generation of large cohorts for robust statistical analyses, while advanced genetic tools, such as CRISPR/Cas9, enable precise gene editing with which to model specific genetic mutations associated with human diseases. Zebrafish metabolic models have been instrumental in elucidating the molecular mechanisms underlying metabolic diseases, studying the effects of environmental factors, and identifying potential therapeutic targets. Additionally, the permeability of zebrafish embryos to small molecules facilitates drug discovery and screening, offering a rapid and economical approach to identifying compounds with therapeutic potential. In conclusion, zebrafish cardiovascular and metabolic disease models continue to contribute significantly to our perception of disease pathogenesis, providing a platform for translational research and developing novel therapeutic interventions. The versatility, scalability, and genetic manipulability of zebrafish position them as an invaluable asset in unraveling the complexities of cardiovascular and metabolic diseases. This review presents an overview of the zebrafish model's key features and contributions to investigating cardiovascular and metabolic disorders. We discuss the benefits and drawbacks of using zebrafish models to study human disease and the critical findings revealed by the progress in this endeavor to date.

Control of multiple herbicide-resistant waterhemp (Amaranthus tuberculatus) with acetochlor-based herbicide mixtures in corn

Abstract Waterhemp is a summer annual, broadleaf weed with high fecundity, short seed longevity in the soil, and wide genetic diversity. Populations have evolved resistance to five herbicide modes of action (Groups 2, 5, 9, 14, and 27), which are present across southern Ontario; this has increased the challenge of controlling this competitive weed species in corn, the most important grain crop produced worldwide, and the highest value agronomic crop in Ontario. Acetochlor is a Group 15 soil-applied residual herbicide that has activity on many grass and broadleaf weeds but has yet to be registered in Canada. The objective of this study was to ascertain whether mixtures of acetochlor with flumetsulam, dicamba, atrazine, isoxaflutole/diflufenican, or mesotrione + atrazine applied preemergence would increase the control of multiple herbicide-resistant (MHR) waterhemp in corn. Five field trials were conducted between 2022 and 2023. No corn injury was observed. Acetochlor applied alone controlled MHR waterhemp 97% 12 weeks after application (WAA). All herbicide mixtures controlled MHR waterhemp similarly at ≥98% 12 WAA; there were no differences among herbicide mixtures. Flumetsulam, dicamba, and atrazine provided lower MHR waterhemp control than all other herbicide treatments and did not reduce density or biomass. Acetochlor reduced waterhemp density 98%, while the acetochlor mixtures reduced density similarly at 99 to 100%. This study concludes that the acetochlor mixtures evaluated provide excellent waterhemp control; however, control was not greater than acetochlor alone. Herbicides herbicide mixtures should be used as a best management practice to mitigate the evolution of herbicide resistance.

Diving into the zebrafish brain: exploring neuroscience frontiers with genetic tools, imaging techniques, and behavioral insights.

The zebrafish (Danio rerio) is increasingly used in neuroscience research. Zebrafish are relatively easy to maintain, and their high fecundity makes them suitable for high-throughput experiments. Their small, transparent embryos and larvae allow for easy microscopic imaging of the developing brain. Zebrafish also share a high degree of genetic similarity with humans, and are amenable to genetic manipulation techniques, such as gene knockdown, knockout, or knock-in, which allows researchers to study the role of specific genes relevant to human brain development, function, and disease. Zebrafish can also serve as a model for behavioral studies, including locomotion, learning, and social interactions. In this review, we present state-of-the-art methods to study the brain function in zebrafish, including genetic tools for labeling single neurons and neuronal circuits, live imaging of neural activity, synaptic dynamics and protein interactions in the zebrafish brain, optogenetic manipulation, and the use of virtual reality technology for behavioral testing. We highlight the potential of zebrafish for neuroscience research, especially regarding brain development, neuronal circuits, and genetic-based disorders and discuss its certain limitations as a model.

De novo transcriptome for Chiloscyllium griseum, a long-tail carpet shark of the Indian waters

Sharks have thrived in the oceans for 400 million years, experienced five extinctions and evolved into today’s apex predators. However, enormous genome size, poor karyotyping and limited tissue sampling options are the bottlenecks in shark research. Sharks of the family Orectolobiformes act as model species in transcriptome research with exceptionally high reproductive fecundity, catch prominence and oviparity. The present study illustrates a de novo transcriptome for an adult grey bamboo shark, Chiloscyllium griseum (Chondrichthyes; Hemiscyllidae) using paired-end RNA sequencing. Around 150 million short Illumina reads were obtained from five different tissues and assembled using the Trinity assembler. 70,647 hits on Uniprot by BLASTX was obtained after the transcriptome annotation. The data generated serve as a basis for transcriptome-based population genetic studies and open up new avenues in the field of comparative transcriptomics and conservation biology.

Multiple records of the introduced parthenogenetic Smooth-scaled Tegulet, <i>Gymnophthalmus underwoodi</i> Grant 1958, in Puerto Rico

The introduction of invasive species to islands can be devastating to local biota. While many invasive species’successful colonization of new habitats can be attributed to features like high fecundity or low mate selectivity,parthenogenetic species pose a unique threat in their ability to reproduce asexually at high rates. The Smooth-scaledTegulet (Gymnophthalmus underwoodi), first described from Barbados in the 1950s, has since been documented as anintroduced species across additional Lesser and Greater Antillean islands as well as northwestern Brazil and Venezuela.Herein we report multiple individuals from Puerto Rico, including the first genetic records, which indicate that theindividuals on this island are most closely related to populations recorded from Brazil and Montserrat. Additionalgenetic information is necessary to determine the timing and migration of this species across the Caribbean. Regardless,the continued geographic expansion of this parthenogen across the Caribbean could present a threat to local fauna.

Biology of pink bollworm Pectinophora gossypiella (Saunders) on cotton as influenced by temperature

A laboratory experiment was conducted to study the biology of pink bollworm Pectinophora gossypiella (Saunders) on cotton at four different temperature levels. It was found that males have a considerably shorter total life cycle duration on cotton at 35±1°C (29.5 days) followed by 30±1°C (37.2 days), 25±1°C (46.9 days) and highest at 20±1°C (50.8 days). Similarly, minimum total life cycle duration of female P. gossypiella was recorded at 35±1°C (30.2 days) followed by 30±1°C (38.0 days), 25±1°C (47.3 days) and maximum at 20±1°C (51.7 days). The highest fecundity was observed at 30±1°C (106.2) followed by 25±1°C (100.1), 35±1°C (60.1) and lowest at 20±1°C (55.2). Male as to female sex ratio was highest at 35±1°C (1:1.5) followed by 25±1°C (1:1.4), 30±1°C (1:1.3) and lowest at 20±1°C (1:1.2). These findings revealed that variation in temperature significantly influences the life cycle duration, fecundity and sex ratio of pink bollworms on cotton, with higher temperatures accelerating development and enhancing reproductive success.

Demographic Parameters of Anthocoris minki Dohrn (Hemiptera: Anthocoridae) Reared on Common Bean (Phaseolus vulgaris L.), Faba Bean (Vicia faba L.) and Pea (Pisum sativum L.) as Egg Laying Media.

Anthocoris minki Dohrn (Hemiptera: Anthocoridae) is used as a biological control agent of various agricultural pests. This study determined the effect of different egg laying materials, i.e., faba bean, common bean, and pea on population parameters of A. minki using age-stage, two-sex life table. The longest (34.45 d) and the shortest (21.32 d) adult longevity was noted on common bean and pea, respectively. Likewise, the highest (92%) and the lowest (69%) preadult survival rate was recorded on faba bean and pea, respectively. The highest fecundity (93.74 eggs/female) was noted on faba bean followed by common bean (43.95 eggs/female) and pea (48.69 eggs/female). Oviposition period remained unaffected, while higher oviposition days (22 d) were noted on faba bean compared with common bean (10 d) and pea (14 d). The shortest and the longest adult pre-oviposition period and total pre-ovipositional period were calculated for common bean and pea, respectively. The highest intrinsic rate of increase (r) (0.1159 d-1) and finite rate of increase (λ) (1.1229 d-1) were noted on common bean, while the lowest (r = 0.0939 d-1; λ = 1.0985 d-1) were noted on pea. Paired bootstrap analyses indicated that the highest net reproductive rate (R0) (43.12 offspring) was recorded on faba bean. Egg hatching rate significantly differed among plants (P < 0.01) and it was 80.50%, 71.10%, and 38.90% on common bean, faba bean and pea, respectively. It is concluded that faba bean would be the most suitable host for mass rearing of A. minki, while pea proved unsuitable.

No geographical differences in male mate choice in a widespread fish, Limia perugiae.

Behavior, like most other traits, can have a spatial component, and variability of behavior at the population level is predicted. In this article, we explore male mate choice at this level. Male mate choice, while maybe not as common as female choice, is expected to evolve when males respond to significant variation in female quality and, for example, prefer females with higher fecundity. In fishes, higher fecundity is associated with larger body size, an easily measured trait. In this study, we investigated the presence of male mate choice for larger females in a widespread species of livebearing fish, Limia perugiae, while comparing preferences between populations. We hypothesized that environmental variation, for example, in the form of salinity, might result in population differences. Using dichotomous choice tests, we analyzed behavioral data for 80 individuals from 7 distinct populations from Hispaniola. We found that L. perugiae males significantly preferred large females, but there was no significant statistical variation between populations.

Little evidence for color- or size-based mating preferences by male strawberry poison frogs (Oophaga pumilio)

While there are many studies documenting female mating preferences across taxa, male mate choice remains relatively understudied. Male mate choice often develops when there is variation in female quality and thus the fitness benefits of mating with particular females. Specifically, males tend to prefer females with traits that confer direct fitness benefits such as large body size, which may be linked with high fecundity. Prior work has shown that females of the strawberry poison frog, Oophaga pumilio, prefer males bearing certain coloration (most often the female’s own color), and that this preference can be learned through maternal imprinting. Females have been shown to prefer larger males as well. Here we test whether similar mate preferences for color and size exist in males of this species using two-way choice tests on captive bred male O. pumilio. In each test focal males were placed in an arena with two stimulus females: either both of the same size but differing in color, or both of the same color but differing in size. We found only weak evidence for behavioral biases toward particular colors and no evidence for biases toward larger females, suggesting that males of O. pumilio do not predictably choose mates based on these female traits. Despite several aspects of their natural history that suggest males have reasons to be choosy, our findings suggest that the cost of mate rejection may outweigh any fitness benefits derived from being selective of mates. Studies of additional populations, ideally conducted on wild individuals, are needed to better understand the range of conditions under which males may exhibit mate choice and the types of traits on which they base these choices.Significance statementTo fully understand the fitness landscapes and evolutionary trajectories that result from sexual selection, we need to understand when and how the mate preferences of the two sexes act and interact. While female mate choice has been widely studied, male mate choice remains poorly understood. To help bridge this gap, we studied male mate preferences in the strawberry poison frog Oophaga pumilio, a small brightly colored frog for which female preferences for male color and size have been well-documented. We found no evidence that male O. pumilio exhibit mate preferences based on female size and little evidence for male mate preferences based on female color. This is surprising given that larger females are often more fecund, male O. pumilio are known to exhibit color-based behavioral biases in the context of male-male competition, and both sexes provide parental care.

Review of the globally invasive freshwater mussels in the genus Sinanodonta Modell, 1945

AbstractIn this review, we synthesize the current knowledge of the biology, ecology, and impact of Sinanodonta freshwater mussels (Bivalvia, Unionidae), native to East Asia, that have successfully invaded Europe, Central America, North Africa, and several Asian regions. The main introduction pathways of Sinanodonta were reconstructed based on DNA sequence data and distribution records. We show that invasive lineages of Sinanodonta belong to three species, namely, S. woodiana s. str. (“temperate invasive” lineage), S. pacifica (“tropical invasive” lineage), and S. lauta. Their generalist fish-dispersed larvae, short life span, high fecundity, use by humans for multiple purposes, and ability to establish populations in anthropogenically disturbed conditions were identified as crucial traits driving their invasions. Information on the consequences is scarcer, but Sinanodonta can impact native species through larval parasitism, host fish/food competition, and parasite transmission. In addition, ecosystem effects through their filtration—biodeposition—excretion activity and the occurrence of massive die-offs were detected. Ecosystem services and disservices have not yet been quantified, even at local scales, and management methods in the invasive range are understudied. A better understanding of Sinanodonta ecology, impacts, and management options is urgently needed to make informed decisions and set realistic and impactful restoration goals.

Ecotoxicological Effects of Potassium Dichromate on the Tadpole Shrimp Triops longicaudatus

The tadpole shrimp Triops longicaudatus is a freshwater crustacean with fast embryonic and larval development, short life cycle, and high fecundity. They are very active swimmers of a reasonable size, easy to spot and record. Such characteristics make it a promising candidate as an experimental model in ecotoxicology to evaluate the effects of aquatic pollutants, particularly using its locomotor behavior as an endpoint. To evaluate the sensitivity of T. longicaudatus and develop endpoints of interest, we conducted exposure experiments with lethal and sub-lethal concentrations of potassium dichromate, a compound known for its ecotoxicological importance and as a hexavalent chromium source. The endpoints evaluated were mortality, growth, sexual maturation, reproductive output, cholinesterase activity and locomotor/swimming behavior. The 96 h median lethal concentration was found to be 65 µg/L. Furthermore, exposure to potassium dichromate at higher concentrations had a significant negative impact on the growth rate of T. longicaudatus in terms of both body mass and length. The time for maturation was also delayed at higher concentrations. In addition, locomotor behavior allowed for the discrimination of all tested chromium concentrations and the control group and from each other, proving to be the most sensitive endpoint. Overall, the data support the potential of T. longicaudatus as a model for ecotoxicity testing, using apical endpoints with impact at the population level; in particular, results suggest that behavior assessments in this species might be useful for detecting hazardous compounds in environmental monitoring of freshwater ecosystems.