1,721,064 research outputs found
Evolutionary ecology of parasite diversity in African Great Lakes and beyond
No full textMetazoan parasites encompass a high proportion of global species diversity with neodermatan parasitic flatworms having one of the most successful evolutionary transitions to parasitism in terms of species numbers. However, ecological and evolutionary mechanisms structuring neodermantan assemblages remain poorly understood. African Great Lakes and their fauna are among the prime model systems for evolutionary research. Despite their regulatory role and functional importance in the ecosystem, until recently, parasitic organisms have been mostly ignored in these biodiversity hotspots. Our research in the region of African Great Lakes provides new insights on ecological and evolutionary dynamics of parasitic flatworms highlighting the interplay between environmental and host characteristics. Our work reveals patterns driving both macro- and microevolutionary dynamics of parasites including the effect of past lake-level changes, host diversity and migration pattern, and interspecies facilitation of infection. We present the importance of stress responses in parasite adaptive evolution, which might affect the fitness, infectivity, and virulence of these organisms, as well as the (re-)emergence infectious diseases in response to environmental disturbance. Accordingly, we identified the first potential molecular function linked to an evolutionary radiation of flatworms.Invited talk, Natural History Museum in Osl
Evolutionary ecology of parasite diversity in African Great Lakes and beyond
No full textMetazoan parasites encompass a high proportion of global species diversity with neodermatan parasitic flatworms having one of the most successful evolutionary transitions to parasitism in terms of species numbers. However, ecological and evolutionary mechanisms structuring neodermantan assemblages remain poorly understood. African Great Lakes and their fauna are among the prime model systems for evolutionary research. Despite their regulatory role and functional importance in the ecosystem, until recently, parasitic organisms have been mostly ignored in these biodiversity hotspots. Our research in the region of African Great Lakes provides new insights on ecological and evolutionary dynamics of parasitic flatworms highlighting the interplay between environmental and host characteristics. Our work reveals patterns driving both macro- and microevolutionary dynamics of parasites including the effect of past lake-level changes, host diversity and migration pattern, and interspecies facilitation of infection. We present the importance of stress responses in parasite adaptive evolution, which might affect the fitness, infectivity, and virulence of these organisms, as well as the (re-)emergence infectious diseases in response to environmental disturbance. Accordingly, we identified the first potential molecular function linked to an evolutionary radiation of flatworms.Invited talk, Natural History Museum in Osl
Diversity of fish parasites in a South Carolina estuary - interesting infection patterns and taxonomic hurdles
No full textIn April and May of 2023, sampling of fish parasite fauna was conducted in the Stono River estuary, in South Carolina, USA. The sampling and the following research of collected parasites were done as part of a BioBlitz, which is a project with an aim of recording all living species within a chosen area, such as urban park or nature reserve. In this case, Stono River estuary is protected as a Stono Preserve area because of its history and the biodiversity present. In this study, 125 fish specimens of 12 genera (17 species) were caught and inspected for parasites; members of only six genera (nine species) were infected: Anchoa (A. mitchilli), Fundulus (F. confluentus, F. heteroclitus, F. majalis), Gambusia (G. holbrooki), Gobiosoma (G. bosc), Menidia (Menidia sp.) and Mugil (M. cephalus, M. curema). From these hosts, 130 parasites were collected, and identified based on their morphology and genetic markers (sequences of 28S, 18S and ITS rDNA). The 15 species observed belonged to different lineages of monopisthocotylan flatworms (Fundulotrema, Gyrodactylus, Ligophorus, Salsuginus), polyopisthocotylan flatworms (Metamicrocotyla) and copepods (Bomolochus, Caligus, Ergasilus, Naobranchia). From all screened hosts, species of Ligophorus have the highest mean intensity and prevalence, and Fundulotrema the lowest. Furthermore, M. cephalus harbors the highest parasite species richness (seven), and Anchoa mitchilli and Menidia sp. the lowest (one per each species). Some of the parasites identified present new records for the Atlantic coast of the USA. Sampled parasites show strong patterns of host-specificity and can be found in different habitats within the estuary, such as creeks, small lakes and water reservoirs. This study points to striking lack of molecular data available for North American fish parasites. Greater knowledge of fish parasite diversity in estuaries would help in understanding how parasite diversity is influenced by changing abiotic factors and global climate change
Diversity of fish parasites in a South Carolina estuary - interesting infection patterns and taxonomic hurdles
No full textIn April and May of 2023, sampling of fish parasite fauna was conducted in the Stono River estuary, in South Carolina, USA. The sampling and the following research of collected parasites were done as part of a BioBlitz, which is a project with an aim of recording all living species within a chosen area, such as urban park or nature reserve. In this case, Stono River estuary is protected as a Stono Preserve area because of its history and the biodiversity present. In this study, 125 fish specimens of 12 genera (17 species) were caught and inspected for parasites; members of only six genera (nine species) were infected: Anchoa (A. mitchilli), Fundulus (F. confluentus, F. heteroclitus, F. majalis), Gambusia (G. holbrooki), Gobiosoma (G. bosc), Menidia (Menidia sp.) and Mugil (M. cephalus, M. curema). From these hosts, 130 parasites were collected, and identified based on their morphology and genetic markers (sequences of 28S, 18S and ITS rDNA). The 15 species observed belonged to different lineages of monopisthocotylan flatworms (Fundulotrema, Gyrodactylus, Ligophorus, Salsuginus), polyopisthocotylan flatworms (Metamicrocotyla) and copepods (Bomolochus, Caligus, Ergasilus, Naobranchia). From all screened hosts, species of Ligophorus have the highest mean intensity and prevalence, and Fundulotrema the lowest. Furthermore, M. cephalus harbors the highest parasite species richness (seven), and Anchoa mitchilli and Menidia sp. the lowest (one per each species). Some of the parasites identified present new records for the Atlantic coast of the USA. Sampled parasites show strong patterns of host-specificity and can be found in different habitats within the estuary, such as creeks, small lakes and water reservoirs. This study points to striking lack of molecular data available for North American fish parasites. Greater knowledge of fish parasite diversity in estuaries would help in understanding how parasite diversity is influenced by changing abiotic factors and global climate change
A failure to diversify on a surface of exchange: the case of Dolicirroplectanum lacustre, the monogenean parasite infecting African latids
No full textIntraspecific diversification and mitonuclear discordance in the monogenean parasite Dolicirroplectanum lacustre, co-introduced with the invasive Nile perch
No full textParasites typically speciate faster, and become more species-rich than their hosts. This especially holds in large and long-lived hosts. Most African lates perches (Latidae), some of the largest freshwater fishes, host only a single monogenean flatworm: Dolicirroplectanum lacustre. This parasite has 'failed to diverge', but displays high morphological variability, with two morphotypes identified.
The Nile perch (Lates niloticus) is a notorious invasive species. The introductions of Nile perch from lakes Albert and Turkana into lakes and rivers in the Lake Victoria region led to the impoverishment of the trophic food webs, particularly well documented in Lake Victoria. Along with the introductions of the Nile perch, its parasites were co-introduced.
To investigate the pattern of parasite co-introduction, we studied the intraspecific diversity of D. lacustre from Nile perch in Lake Albert and Lake Victoria by assessing morphological and genetic differentiation. A single morphotype is suggested to be co-introduced in Lake Victoria. Based on our results, we reported reduced genetic and morphological diversity in Lake Victoria, resulting from a founder effect. The diversification in the COI mitochondrial gene portion was directly linked with the morphotypes, while the nuclear gene portions indicated conspecificity. Mitonuclear discordance within the morphotypes of D. lacustre indicates an incomplete reproductive barrier between the morphotypes
Rethinking the Nile Perch Species Complex: Diversification and Phenotypic Plasticity in the most widespread fisheries keystone species in African Freshwaters
No full textStudying the diversity of freshwater fish species, in particular, the Nile perch complex is crucial for understanding and managing African freshwater ecosystems. As top predators, they play a significant role in regulating fish populations and influencing ecosystem functioning. Taxonomic uncertainties within the complex necessitate further investigation.
We study the morphological diversification of lates perches (Latidae) across Afrotropical freshwaters. We hypothesize morphological differentiation between Nile perches from various basins and habitats, particularly between the Congo and Nile rivers. We expect an increased morphospace in lacustrine environments compared with riverine environments, reflecting the presence of more species in the lakes. We aim to assess the status of two sympatric species in Lake Turkana.
Specimens of lates perches were collected from various historical collections and included in the morphological study. A subsample underwent X-ray or CT scanning. Morphological measurements (37 parameters) were obtained using a digital caliper. Meristic data, including fin formulas, scale counts, and vertebral counts were recorded.
Genetic data were retrieved from ten specimens of Lake Turkana (Kenya). Fin clips were collected and DNA extraction was performed, followed by Illumina sequencing (with targeted bait capture), and Sanger sequencing of the targeted markers (11 mitochondrial, 1 nuclear). Phylogenetic analyses were conducted using maximum likelihood estimation and Bayesian inference.
The morphological data reveal a remarkably conserved morphology with local variation. Based on the combined genetic and morphological evidence, we classify Lates niloticus var. macrolepidota from the Congo River as a distinct species, elevated to Lates macrolepidotus Pellegrin, 1922. We observe east-west clinal variation, with Guinean populations showing greater similarity in meristics to L. macrolepidotus, likely influenced by the predominance of rainforest ecosystems and habitats. The endemic species from lakes Turkana and Albert exhibit morphological differences from the co-occurring L. niloticus, but without species-level genetic differentiation in Lake Turkana
Limited diversification in the monogenean oparasite Dolicirroplectanum lacustre on African lates perches despite a broad habitat range
No full textINTRODUCTION: While parasites often speciate faster than their hosts, African freshwater lates perches (Latidae) host only a single monogenean gill parasite, Dolicirroplectanum lacustre. This species shows limited diversification across various habitats. In contrast, marine and brackish latids in the Indo-Pacific region host a more species-rich assemblage of gill parasites. The introduction of Nile perch (Lates niloticus), an invasive species transported from lakes Albert and Turkana to the Lake Victoria basin, presents an opportunity to study the parasite’s genetic and morphological diversification.
MATERIALS AND METHODS: To understand the diversity patterns in D. lacustre, we studied its populations across multiple sites, including Lake Albert, Lake Victoria, Lake Turkana, and the Congo River. Morphological and genetic analyses were conducted to explore genetic differentiation within the species.
RESULTS: Our analysis revealed two morphotypes within D. lacustre, with one restricted to Lake Albert displaying a distinct mitochondrial haplotype. Despite this mitochondrial divergence, nuclear gene markers confirmed conspecificity. Only one of the two morphotypes was found in Lake Victoria, where D. lacustre showed reduced genetic and morphological diversity. The screening of host gills in Lake Turkana and the Congo River has expanded the known range of D. lacustre.
CONCLUSION: Despite occupying diverse freshwater habitats across Africa, D. lacustre remains a single, morphologically constrained species with minimal diversification. The co-introduction to new environments has reduced the parasite’s diversity through founder effects. Overall, diversification within D. lacustre has been limited to morphotype differentiation rather than full speciation. Further examination of populations from Lake Turkana and the Congo River will give us more insight into its diversification and that of its hosts, and comparative genomics will shed light on the genomic mechanisms behind the observed lack of speciation. Altogether, this study may highlight how the stability of aquatic environments may limit diversification potential in host-parasite systems
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