Publications by authors named "Martin J Genner"
Climate warming drives population trajectories of freshwater fish.
Proc Natl Acad Sci U S A
December 2024
Climate change has emerged as a key threat to biodiversity, leading to broad-scale shifts in distributions of marine and terrestrial species as they attempt to track thermally suitable habitat. By contrast, our understanding of climate responses of freshwater species is relatively undeveloped, limiting our knowledge of whether projected warming will lead to freshwater biodiversity loss. Here, we linked a multicontinental database of riverine fish population abundance time series collected from 1958 to 2019 to temperature data from the same period.
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- A dataset of μCT scans from 56 species of Lake Malawi cichlid fishes is introduced, capturing a wide range of morphological variations among these fish.
- The text discusses the ecomorphological groupings of the species and suggests potential macroevolutionary research that could utilize this dataset.
- An efficient methodology for scanning, averaging 23 specimens per hour while ensuring high resolution, is outlined, showcasing its effectiveness through 3D bone models reconstructed from the collected data.
Article Synopsis
- Cichlid fishes of the genus Oreochromis, or tilapia, are crucial for inland fisheries and aquaculture, but hybridization with non-native species threatens local biodiversity.
- Researchers studied hybridization patterns in tilapia by analyzing the genomes of 575 individuals from 23 species in Tanzania, where both ancient and recent hybridization occurs.
- Their findings reveal significant historical gene flow and the hybrid speciation of a specific species, highlighting concerns for conservation and the future of aquaculture practices.
Article Synopsis
- Environmental changes like temperature and turbidity significantly influence predator-prey dynamics among wild fish, specifically Trinidadian guppies.
- The study showed that environmental factors accounted for 17.6% of the differences in predator species composition, with certain conditions favoring predator presence.
- Warmer, deeper, and clearer waters led to increased predator behavior, such as quicker responses to prey and more frequent attacks, emphasizing the importance of understanding multiple environmental stressors in ecological studies.
Article Synopsis
- The mechanosensory lateral line system in fishes is crucial for survival behaviors like finding food and navigating in low-light conditions, and its morphology may undergo disruption during ecological speciation.
- In a study of two ecomorphs of the cichlid fish Astatotilapia calliptera in Lake Masoko, it was found that the deeper-water zooplanktivorous ecomorph has larger lateral line canal pores compared to the shallower-water invertebrate-feeding ecomorph.
- The findings highlight the early divergence in lateral line morphology as a potential contributor to adaptive radiation, an indication of how ecological specialization can influence sensory adaptations.
Article Synopsis
- Researchers investigated how nuclear genetic material from environmental DNA (eDNA) can reveal population genetics of cichlid fish in Lake Masoko, Tanzania.
- * The study focused on two genetically distinct ecomorphs of cichlids separated by a thermo-oxycline at 15 meters depth, indicating diverging populations within the lake.
- * By analyzing single nucleotide polymorphisms (SNPs) from both eDNA and fish samples, the team confirmed that eDNA can accurately reflect the genetic structure of populations across different depths in the lake.
Article Synopsis
- - A new cichlid fish species named Lethrinops chilingali has been identified from Lake Chilingali in Malawi, distinguished by specific jaw structure and lacking certain traits of related species.
- - Unique physical characteristics, such as a broken horizontal stripe on females and altered facial features, set Lethrinops chilingali apart from similar species like Lethrinops lethrinus.
- - This species is likely extinct in the wild, as there have been no sightings since 2009, although it is still being bred in captivity.
Article Synopsis
- The study focuses on discovering cryptic species in tropical freshwater ecosystems, specifically through DNA sequencing and phylogenetic analysis of Mochokidae catfishes.
- Researchers discovered approximately 50 potential new species within the Chiloglanis genus, nearly increasing its species richness by 80%, highlighting the importance of these habitats for biodiversity.
- Biogeographic findings indicated the Congo Basin as key to mochokid diversity and suggested different diversification processes for the genera Synodontis and Chiloglanis, with the former showing in situ evolution and the latter indicating significant dispersal.
Article Synopsis
- Climate change is impacting the distribution and numbers of marine fish species, raising concerns for future commercial fisheries.
- An analysis of data from 198 fish species in the Northeast Atlantic shows that temperature, salinity, and depth are critical factors influencing fish community structure.
- Projections for 2050 and 2100 indicate significant shifts in fish communities due to climate change, especially in areas experiencing greater warming, which could affect commercial fishing opportunities significantly.
Article Synopsis
- The study investigates how differences in the anatomical features of the lateral line system in fish affect their collective behaviors, specifically shoaling.
- Researchers focused on two distinct fish species and their hybrids, finding that larger canal pore sizes and fewer superficial neuromasts lead to closer proximity among fish during group behaviors.
- Hydrodynamic modeling demonstrated that canal-based sensors are more effective in detecting nearby fish movements, suggesting a mechanism for how fish sense and respond to their neighbors in a group setting.
Article Synopsis
- Freshwater fishes, like the cichlid Astatotilapia calliptera in Lake Masoko, have undergone rapid speciation along depth gradients, with distinct ecomorphs developing in just 1,000 years.
- Researchers used genome-wide transcriptome data to analyze the molecular mechanisms behind these changes, specifically focusing on gene expression and splicing variations.
- They discovered thousands of differently expressed genes, with certain regulatory variants significantly influencing craniofacial development, indicating that modifications in gene regulation are key to early-stage speciation and adaptive divergence.
Article Synopsis
- - Epigenetic variation can influence gene expression and lead to differences in traits among populations adapting to different environments, specifically in the early stages of speciation.
- - The research examines the DNA methylome changes in two morphologically and ecologically distinct ecomorphs of Astatotilapia calliptera in Africa's Lake Masoko, which evolved about 1,000 years ago, despite no fixed genetic differences.
- - Findings show extensive differences in methylation patterns related to critical biological functions, supporting the idea that epigenetics plays a role in early vertebrate speciation, with some traits being inherited across generations.
Article Synopsis
- - Cichlid fish are vital for tilapia aquaculture and fisheries, but distinguishing between species is challenging due to morphological similarities and hybridization with non-native populations in Africa.
- - A new genotyping panel using SNPs has been developed to accurately identify species and hybrids in tilapia, proving to be more effective than traditional methods like microsatellites and phenotype classification.
- - Case studies reveal that introduced tilapia species are increasingly becoming established in the wild, posing risks to native species, highlighting the need for better broodstock management to conserve biodiversity.
Article Synopsis
- The mesopelagic zone of the ocean, located 200-1000 m below the surface, is crucial for ecosystem health and hosts a significant amount of small fish.
- New acoustic methods are being used to estimate fish biomass more accurately, revealing that the Southern Ocean's mesopelagic fish biomass could be as high as 570 million tonnes.
- The research also highlights that fish biomass is highest near the seasonal ice-edge, which is vital for the feeding of penguins and seals, indicating potential risks to these ecosystems with climate change.
Article Synopsis
- Epigenetic variation influences gene expression and can be passed down through generations, but its role in natural adaptive changes is not well understood.
- The research focuses on Lake Malawi cichlid fishes, showcasing significant phenotypic diversity despite minor genetic differences, making them an ideal subject for studying how epigenomics contributes to adaptation.
- The study finds notable differences in DNA methylation patterns between species, particularly in genes related to energy use and metabolism, highlighting a connection between diet and epigenetic changes, along with shared developmental gene patterns across tissues.
Article Synopsis
- The accuracy of DNA metabarcoding relies heavily on high-quality reference libraries, but current options to obtain and manage sequence data are limited.
- This study introduces a pipeline for downloading, cleaning, and annotating mitochondrial DNA sequences specifically for fish species, offering features like taxonomic validation and quality control.
- A curated reference library for U.K. marine and freshwater fish is provided, including 241 new sequences, which enhances the coverage for metabarcoding efforts to 93% for common species.
Article Synopsis
- Invasive Nile tilapia are hybridizing with native Korogwe tilapia in southern Tanzania, threatening unique genetic resources.
- Research shows that southern Korogwe tilapia populations are genetically distinct from those in northern Tanzania, having diverged around 140,000 years ago.
- Findings indicate the need for conservation efforts to protect these unique and vulnerable fish populations from hybridization and genetic dilution.
Article Synopsis
- The correction addresses errors found in the original publication of the article.
- It clarifies specific data points or findings that were inaccurately presented.
- This is important for maintaining the integrity and accuracy of the research findings in the field.
Article Synopsis
- Marine environments have warmed by an average of 1°C since the 1850s, affecting the distribution of marine species based on their thermal tolerances.
- A global analysis of 304 marine species shows that abundance is increasing in cooler, poleward areas, while it is declining toward the warmer equatorial regions.
- This trend indicates that future temperature rises (up to 1.5°C by 2050) will further push marine species to shift their distributions, potentially impacting coastal communities reliant on these species.
Article Synopsis
- Schistosomiasis is a serious tropical disease caused by parasitic worms, and new diagnostic methods are needed to detect these parasites in the environment.
- Researchers developed qPCR assays to specifically identify the species Schistosoma mansoni, S. haematobium, and S. japonicum with high accuracy, despite some cross-reactivity issues.
- The use of environmental DNA (eDNA) proved effective in confirming the presence of these parasites in various freshwater sites, suggesting that eDNA monitoring could enhance disease control efforts.
Article Synopsis
- Schistosomiasis affects over 200 million people globally, and improved surveillance methods using environmental DNA (eDNA) could enhance control measures for this neglected tropical disease.
- A new xenomonitoring method was developed to detect schistosome infections in host snails by analyzing eDNA from water they are housed in, improving accuracy even when schistosome eDNA is rare in the environment.
- The results showed that this eDNA-based approach reliably identified S. mansoni infections in all tests and S. haematobium in 92% of tests, suggesting it could be a valuable tool for monitoring infections and guiding interventions in areas where schistosomiasis is endemic.
Article Synopsis
- * Evidence suggests that hybridization occurred between lineages that split 3-4 million years ago, contributing to a mosaic genomic structure in Malawi cichlids, with large genome blocks showing little variation across species.
- * The study finds that genetic variants resulting from hybridization are linked to ecological differentiation, particularly in genes related to immune response and vision, highlighting hybridization's critical role in the rapid evolutionary diversification of these fishes.
Article Synopsis
- The lateral line system in fish helps them detect water movements and environmental cues, critical for finding food and avoiding predators.
- Researchers used X-ray imaging to study how the structure of this system varies among different Lake Malawi cichlid species.
- Findings reveal that the shape of the lateral line canals is closely linked to the fish's diet and jaw structure, highlighting its role in the evolutionary diversity of these cichlids.
Article Synopsis
- Mesopelagic fish, found 200-1000 m deep in the ocean, are the most abundant vertebrates on Earth and play a crucial role in ocean ecosystems.
- Recent research shows that several common species in these waters lack gas-filled swimbladders, which are typically detected using acoustic surveys, leading to possible underestimations of their biomass, especially as one moves towards the Antarctic.
- This shift in fish community composition has significant implications for ecosystem modeling, biomass estimation, and monitoring species that may be affected by climate change and potential overfishing.