Morphological and molecular diversity of freshwater mussels (Unionida) present in Costa Rica
Gardado en:
| Autor: | |
|---|---|
| Formato: | tesis de maestría |
| Data de Publicación: | 2026 |
| Descripción: | Freshwater mussels of the order Unionida represent one of the most threatened groups worldwide; nevertheless, their diversity, ecology, and evolutionary and biogeographic history in Central America have remained poorly studied. This thesis constitutes the first comprehensive effort that integrates molecular, biogeographic, morphological, and ecological evidence to understand the origin, diversification, distribution, and conservation status of freshwater mussels in Costa Rica. To achieve this, phylogenetic relationships and divergence times were reconstructed for different populations and species of the families Unionidae and Mycetopodidae from Mexico, Guatemala, El Salvador, Costa Rica, and Panama, based on concatenated analyses of mitochondrial markers (cox1, nad1, 16S). The results highlight that several traditionally recognized genera are not monophyletic, including Anodontites and Nephronaias, revealing marked morphological plasticity. Divergent lineages likely representing undescribed species (Anodontites cf. trapesialis and Mycetopoda sp.) were identified, we obtained six different clades for Costa Rica, and multiple colonization events from South and North America into Central America were recovered. These events are associated with the progressive closure of ancient marine corridors (the Nicaraguan Seaway and the Isthmus of Panama) from the Miocene to the Pleistocene. This biogeographic history suggests that several populations represent isolated relics resulting from watershed reorganizations, orogenic uplifts, and hydrographic barriers. Regarding the systematics of Costa Rican freshwater mussels, information on distribution, relative abundance, and species composition was compiled across river basins. Six native species and one invasive species were identified, some of which have very restricted distributions and low abundances. Native mussel records do not exceed 100 m in elevation, and the presence of soft substrate banks such as mud and clay in low-flow environments favors species such as Anodontites cf. trapesialis and Mycetopoda sp., while rocky substrates with more dynamic flow favor Arotonaias cyrenoides. Species such as Anodontites cf. tortilis, Nephronaias tempisquensis, and Barynaias caldwelli appear to be more generalist. Host information is currently known only for N. tempisquensis. The invasive species Sinanodonta pacifica has expanded across river basins in the northern and southern Pacific regions of the country, where it can reach abundances that exceed those of native species. This situation, combined with river degradation caused by sand extraction, dam construction, flow diversion, and agricultural contamination, places several native populations at critical risk. Overall, this work provides the first solid foundation for the taxonomic, phylogeographic, ecological, and conservation assessment of Unionida in Costa Rica and Central America. The results underscore the urgent need for studies on genetic connectivity, host specifity, invasive species management, and the preservation of hydrological continuity to ensure the persistence of these unique evolutionary lineages. |
| País: | Kérwá |
| Institución: | Universidad de Costa Rica |
| Repositorio: | Kérwá |
| Idioma: | Inglés |
| OAI Identifier: | oai:kerwa.ucr.ac.cr:10669/103778 |
| Acceso en liña: | https://hdl.handle.net/10669/103778 |
| Palabra crave: | Central America Unionida Mycetopodidae Costa Rica Biogeography Freshwater mollusks Time-calibration |