The diversity of developmental modes in marine gastropods reflects evolutionary adaptations and marked developmental plasticity. Crepipatella peruviana undergoes encapsulated development and hatches as planktotrophic veligers. We tested the effect of an unusual intracapsular food source—tissues from dead sibling embryos (adelphophagy)—on developmental timing, morphology, and physiology of encapsulated embryos that survived to hatching. Capsules containing veligers exposed to adelphophagy were compared with control capsules without added food; we recorded morphological traits, physiological responses, and time to hatching. Access to intracapsular food significantly accelerated encapsulated development, reduced time to hatching, and increased hatchling shell size, velum area, and cilium length relative to control veligers, indicating that embryos were able to exploit the additional food and achieve more advanced development at hatching. No differences in oxygen consumption rate were detected among the groups of encapsulated veligers. These results indicate that C. peruviana exhibits developmental plasticity in response to intracapsular food availability. Our results indicate that encapsulated veligers can opportunistically exploit intracapsular resources such as dead siblings, highlighting a flexible trophic capacity during encapsulated development. From an evolutionary perspective, this flexible trophic capacity makes C. peruviana a valuable model for investigating the functional basis and potential evolutionary relevance of intracapsular feeding in marine gastropods.
Freshwater diatom diversity remains unevenly documented across the Neotropics, limiting assessments of regional biodiversity and biogeographic patterns. We provide a critical, georeferenced synthesis of continental diatoms from Paraná State, southern Brazil, integrating bibliographic records, herbarium collections, nomenclatural revision, and spatial analyses. The compiled dataset comprises 86,775 occurrence records from 3649 samples collected between 1951 and 2025 at 712 georeferenced sites. After taxonomic and nomenclatural updates, 1525 accepted infrageneric taxa belonging to 190 genera, 71 families, and 35 orders were recognized. However, sampling was strongly spatially biased: Only 11.1
Environmental DNA (eDNA) is a non-invasive tool for aquatic biodiversity monitoring that primarily proves qualitative information on species presence but is increasingly used to obtain semi-quantitative estimates of abundance and biomass. Mitochondrial DNA has, due to its cellular abundance, dominated eDNA assay development while the potential of highly repetitive nuclear regions remains largely unexplored. We developed and evaluated an eDNA assay for northern pike (Esox lucius) targeting the 5S ribosomal DNA region, repeated in extremely high numbers (> 20,000 copies) within the pike genome and compared its performance against an established mitochondrial COI marker. Specificity was evaluated in vitro against co-occurring freshwater species and performance was assessed across two controlled experiments on adult and juvenile pike. The repetitive nuclear assay amplified four to seven cycles earlier than the mitochondrial assay in pike tissue, and two to five cycles earlier in the controlled experiments, demonstrating substantially increased signal strength. While highly repetitive nuclear DNA increased eDNA signal strength, a trade-off emerged in terms of specificity, and questions remain regarding interspecies variation of such regions. Highly repetitive nuclear eDNA markers show considerable promise for increasing signal intensity and detection probabilities, offering a promising approach for improving sensitivity of species-specific eDNA monitoring.
Freshwater ecosystems, including rivers, streams, and ponds, are crucial for biodiversity conservation and global biogeochemical processes. However, these environments face threats from anthropogenic activities, climate change, and increased production demands. This study employed environmental DNA (eDNA) metabarcoding to collect data on the diversity and spatial distribution of freshwater eukaryotic microbial communities in tropical regions and assess the effectiveness and constraints of eDNA metabarcoding in tropical freshwater rivers covering a wide spectrum of environmental settings and pollution levels. The assessment of the existing microeukaryotic communities in three Mexican rivers revealed that Ciliophora, Diatomea, and Chlorophyta were the most abundant phyla across all sites, with Ciliophora being particularly prevalent in urban areas. The presence of Arthropoda, Peronosporomycetes, and Mollusca in peri-urban and rural sites indicate more diverse eukaryotic communities compared to urban areas. Genera such as Paramecium, Adinetida, Navicula, Nitzchia, and Trebouxiophyceae were consistently present across all sites and seasons, indicating their adaptability to varying environmental conditions. The study confirmed that physicochemical variables, such as phosphate, Chemical Oxygen Demand (COD), sulfide, nitrate, and nitrite, play a significant role in structuring microeukaryotic communities at sampling sites. The findings emphasize the importance of expanding genomic reference databases for tropical regions and highlight the potential of eDNA metabarcoding as a tool for monitoring biodiversity across various levels of urbanization in tropical aquatic ecosystems.
Biodiversity knowledge is essential for understanding ecosystem stability and resilience. Traditionally, biodiversity research relies on morphological taxonomy; however, advances in environmental DNA (eDNA) metabarcoding offer faster and potentially more comprehensive approaches. This study compares morphological taxonomy and COI metabarcoding for assessing zooplankton (Rotifera, Diplostraca, and Copepoda) biodiversity across four seasons in Lake Volvi (Northern Greece). A total of 60 taxa were identified, with limited overlap between methods: 35
