The Influence of Fragmented Landscapes on Speciation.

In the face of unprecedented global transformations, unraveling the intricate mechanisms governing biodiversity patterns is imperative for predicting and interpreting species responses. An important element in this interplay is fragmentation and the spatial mosaic or arrangement of suitable sites within the landscape. Beyond its well-documented impact on biodiversity loss, fragmented landscapes also influence the origin of biodiversity, by influencing speciation dynamics. This research employs a model that integrates spatial configuration and dispersal abilities of individuals to investigate the impact of landscape configuration on species' evolutionary trajectories. Specifically, we propose a microevolutionary model where individuals are characterized by their dispersal ability and a genome, allowing population evolution and diversification. Space is explicitly characterized by suitable and unsuitable sites that define fragmented landscapes. Our model demonstrates how intermediate dispersal abilities enhance diversification. However, simulations of more fragmented landscapes result in a lower total number of individuals and a lower percentage of occupied sites by individuals, particularly when species have limited dispersal abilities. Furthermore, we have found that intermediate levels of fragmentation can stimulate greater species richness, while higher levels of speciation and extinction events tend to occur under higher fragmentations. Our results also show a non-monotonic dependence of richness on dispersal, supporting the intermediate dispersal hypothesis as promotor of diversification, demonstrating the synergistic effects of landscape configuration and species dispersal ability in the processes of speciation, extinction, and diversification. This impact of fragmentation poses a real challenge for biodiversity in the context of a dynamic world.

Position of Polyclithrum within Gyrodactylidae (Monogenoidea): incongruences between morphological and molecular phylogenies.

This study aimed to enhance our understanding in monogenoid evolution by using morphological and molecular data to determine kinship relationships between species and changes in morphological structures over time. We focused on variations in characteristics among the organisms of the family Gyrodactylidae, concentrating on the phylogenetic position of Polyclithrum with other genera in the family. We collected specimens of Polyclithrum from the striped mullet, Mugil cephalus and Swingleus, and Fundulotrema specimens from mummichog Fundulus heteroclitus in estuarine systems of South Carolina, United States. In addition, we analyzed them and other genera (including e.g., Mormyrogyrodactylus, Gyrodactyloides, and Macrogyrodactylus) using both morphological and molecular (18S rDNA) approaches. We performed phylogenetic trees based on Maximum Parsymony, Maximum Likelihood and Bayesian Inference, and constructed a character morphological matrix by Parsimony Reconstruction of Ancestral Character States method. Our results suggest a homoplastic origin with evolutionary convergences in characters, revealing that there is inconsistency between our data and previously published works based solely on morphological structures of the group. The homoplasy scenario found in Gyrodactylidae can be a result of the limited set of putative homologous morphological features. However, differences between the phylogenies based on morphology and those based on molecular data may arise from both databases. While morphology remains essential in understanding the evolution of this group, molecular data, otherwise, provide a less biased source of information for constructing phylogenetic hypotheses. Combining these data facilitates a better comprehension of the homologous status of morphological features and to understand Gyrodactylidae evolutionary history.

Molecular evidence of new freshwater turtle blood flukes (Digenea: Spirorchiidae) in the intermediate snail host Biomphalaria occidentalis Paraense, 1981 in an urban aquatic ecosystem in Brazil.

In this study, two potentially new species of turtle blood flukes (TBFs) (Digenea: Spirorchiidae) have been recorded from South Brazil. The spirorchiid parasites infect the vascular system of turtles, thereby compromising their health. The life cycle of these parasites is not well studied. The larval stage of cercaria is found in intermediate gastropod hosts, with some species presenting similar morphological characteristics, which can result in misinterpretations when using only morphological taxonomy for species identification. In this study, we recorded a single morphotype belonging to the family Spirorchiidae in Biomphalaria occidentalis in an urban aquatic ecosystem in Brazil. However, molecular data (28S rDNA and cytochrome oxidase subunit I) confirmed the presence of two species of Spirorchiidae in the sampled environment; both phylogenetically close to genera previously studied in freshwater turtles from the Peruvian Amazon. In this study, species characterization was possible because of molecular tools. We recommend using more than one molecular marker in future studies focusing on TBFs, which need attention about their evolutionary history and ecology to understand their distribution in South America.

Checklist of parasites in fish from the upper Paraná River floodplain: An update.

This study provides an updated list of parasite species and their respective hosts in the upper Paraná River floodplain. The list of parasites is structured by phylum, class, order and family, followed by a record of each host species. A total of 315 taxa of parasites were reported, of which 201 were identified at the species level. These 201 species comprise 3 Flagellata, 3 Myxozoa, 50 Monogenea, 43 Digenea, 40 Cestoda, 41 Nematoda, 8 Acanthocephala, 6 Copepoda, 5 Branchiura and 2 Pentastomida, arranged in 84 host fish species. This work carried out in the floodplain of the upper Paraná River contributes to the listing of parasite species and host interactions of the local ichthyofauna. Little is known about these communities and its riches are underestimated due to the high density of fish found in this region, highlighting the importance of conducting studies on the local fauna.

Checklist of parasites in fish from the upper Paraná River floodplain: An update / Lista de parasitos em peixes da planície de inundação do alto rio Paraná: uma atualização

Abstract This study provides an updated list of parasite species and their respective hosts in the upper Paraná River floodplain. The list of parasites is structured by phylum, class, order and family, followed by a record of each host species. A total of 315 taxa of parasites were reported, of which 201 were identified at the species level. These 201 species comprise 3 Flagellata, 3 Myxozoa, 50 Monogenea, 43 Digenea, 40 Cestoda, 41 Nematoda, 8 Acanthocephala, 6 Copepoda, 5 Branchiura and 2 Pentastomida, arranged in 84 host fish species. This work carried out in the floodplain of the upper Paraná River contributes to the listing of parasite species and host interactions of the local ichthyofauna. Little is known about these communities and its riches are underestimated due to the high density of fish found in this region, highlighting the importance of conducting studies on the local fauna.

Resumo Este estudo fornece uma lista atualizada de espécies de parasitos e seus respectivos hospedeiros da planície de inundação do alto rio Paraná. A lista de parasitos está estruturada em filo, classe, ordem e família, seguida do registro de cada espécie de hospedeiro. São relatados 315 táxons de parasitos e, destes, 201 foram identificados por espécie. Essas 201 espécies compreendem: 3 Flagellata, 3 Myxozoa, 50 Monogenea, 43 Digenea, 40 Cestoda, 41 Nematoda, 8 Acanthocephala, 6 Copepoda, 5 Branchiura e 2 Pentastomida, distribuídos em 84 espécies de hospedeiros. Este trabalho, realizado na planície de inundação do alto rio Paraná, contribui para a listagem de espécies de parasitos e interações parasito-hospedeiro da ictiofauna local. Pouco dessas comunidades é conhecida, e suas riquezas são subestimadas devido à alta densidade de peixes encontrados nessa região, destacando-se a importância da realização de estudos sobre a fauna local.