RESUMO
Exploring the phylogenetic signal of morphological traits using geometric morphometry represents a powerful approach to assess the relative weights of convergence and shared evolutionary history in shaping species' forms. We evaluated the phylogenetic signal in shape and size of ventral and dorsal haptoral anchors of 10 species of monogenoids (Hamatopeduncularia, Chauhanellus and Susanlimocotyle) occurring in marine catfish (Siluriformes: Ariidae) from the Atlantic coast of South America. The phylogenetic relationships among these species were mapped onto the morphospaces of shape and size of dorsal and ventral anchors. Two different tests (squared change-parsimony and Kmult) were applied to establish whether the spatial positions in the phylomorphospace were influenced by phylogenetic relationships. A significant phylogenetic signal was found between anchor form and parasite phylogeny. Allometric effects on anchor shape were non-significant. Phylogenetically distant species on the same host differed markedly in anchor morphology, suggesting little influence of host species on anchor form. A significantly higher level of shape variation among ventral anchors was also found, suggesting that the evolutionary forces shaping ventral anchor morphology may operate with differing intensities or exhibit distinct mechanisms compared to their dorsal counterparts. Our results suggest that phylogenetic relationships were a key driver of changes in shape (but not size) of anchors of monogenoids of South American ariids. However, it seems that the emergence of the digitiform haptor in Hamatopenducularia and in some species of Chauhanellus played an important role in the reduction in anchor size and may cause secondary losses of anchors in other groups of monogenoids.
Assuntos
Evolução Biológica , Peixes-Gato , Doenças dos Peixes , Filogenia , Animais , Peixes-Gato/parasitologia , Doenças dos Peixes/parasitologia , América do Sul , Oceano Atlântico , Trematódeos/anatomia & histologia , Trematódeos/classificação , Trematódeos/genética , Infecções por Trematódeos/parasitologia , Infecções por Trematódeos/veterináriaRESUMO
Due to their high specificity, monogenoids from fish provide an interesting model to study historical associations of hosts and parasites. High agreement between host and parasite phylogeny is often interpreted as evidence of cospeciation. However, cophylogenetic signal may also arise from other, either adaptive or non-adaptive, processes. We applied the recently developed Cophylospace Framework to better understand the evolutionary relationship between monogenoids and marine catfish from the Atlantic coast of South America. The associations between 12 marine catfish and 10 monogenoid species were assessed. Molecular data of host and parasite species were used for phylogenetic reconstruction. We used anchor morphology based on Procrustes coordinates to evaluate whether closely related hosts are associated with morphologically similar parasites. To assess the association between parasite phylogeny and host morphology, we produced a distance matrix based on morphological characters of catfishes. Agreement between phylogenies and between phylogeny and morphology was measured using Procrustes R2 computed with PACo. The parasite phylogeny obtained in this study represents the first complete phylogenetic hypothesis of monogenoids parasitizing ariids from South America. The Cophylospace analysis suggested that phylogenetic and morphological distance of monogenoids contributes similarly to explain the pattern of hostparasite associations, whereas parasite phylogeny is more strongly associated with the morphological traits of the hosts than with host phylogeny. This evidence suggests that cospeciation is not a major force accounting for diversification in the monogenoids studied. Rather host morphological traits seem to be a more important driver, which conforms with evidence from other hostâmonogenoid systems.
Assuntos
Peixes-Gato , Parasitos , Trematódeos , Animais , Filogenia , Peixes-Gato/parasitologia , Evolução Biológica , Interações Hospedeiro-Parasita , América do SulRESUMO
Ecological data on marine mammal parasites represent an excellent opportunity to expand our understanding of host-parasite systems. In this study, we used a dataset of intestinal helminth parasites on 167 long-finned pilot whales Globicephala melas (Traill, 1809) from seven localities in the Faroe Islands to evaluate the extent to which the host's age and sex influence the occurrence, richness, and nested pattern of helminth parasites and the importance of individual hosts to the helminth community. We found positive effects of age on both the occurrence and richness of helminths. Older host individuals showed an ordered accumulation of parasites, as evidenced by the nested pattern in their composition. Males had a higher occurrence of parasites than females, but the richness of helminths did not differ between sexes. Our findings suggest that differences in host-parasite interactions in long-finned pilot whales result mainly from age-structured variations in biological and behavioral characteristics.
Assuntos
Helmintíase/epidemiologia , Helmintos/isolamento & purificação , Interações Hospedeiro-Parasita/fisiologia , Baleias Piloto/parasitologia , Distribuição por Idade , Fatores Etários , Animais , Dinamarca/epidemiologia , Feminino , Humanos , Intestinos/parasitologia , Masculino , Fatores SexuaisRESUMO
A new monogenean species, Ligophorus yucatanensis n. sp. from the gills of the flathead mullet Mugil cephalus from the Yucatan Peninsula, Mexico, is described. The new species can be differentiated from all other species of Ligophorus by the morphology of the accessory piece of the copulatory organ. Its main lobe is cylindrical, tunnelled expanded distally, slightly bowed with a characteristic membranous opening at level of medial bifurcation of the accessory piece, forming a thick-walled bulbshaped expansion that ends in a round labium. The secondary lobe is spatulate, straight, and shorter than the main lobe. In addition, the new species can be distinguished from other species by the morphology of the haptoral ventral bar, and the distal end of the vaginal duct. Furthermore the ventral anchors are shorter than those of all other species of Ligophorus reported in the Gulf of Mexico and Caribbean Sea. In addition, the zoogeographical records of Ligophorus spp. on the M. cephalus species complex are briefly reviewed and updated.