Session 15: ASIH Stoye General Ichthyology IIIRoom: Ballroom 111C2022-07-29 08:00 - 09:15 |
| Moderator: Prosanta Chakrabarty |
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1. 08:00 Modularity Drives Diversity in Armored Catfishes. Corinthia Black*, Auburn University; Jonathan Armbruster, Auburn University corinthiablack@gmail.com
The evolution of morphological diversity has held a long-standing fascination. In particular, do bodies evolve as single, integrative units, or do different body parts evolve as semi-independent units (aka modules). Suckermouth armored catfishes have a unique morphology that lends nicely to modularity and integration studies. In addition to a ventrally facing oral jaw that directly attaches to surfaces, the neurocranium and pectoral girdle are fused, which limits movement of the anterior part of the body. Jaw operation includes both losses and novel biomechanical connections, which allow jaw rami to operate separately. With food manipulation primarily located within the head, it would seem likely that the head and body may act as separate modules that can evolve independently; for example, similar jaw morphologies may be found in different body shapes or vice versa. If true, one would expect to see a two-module system where the head and tail are morphologically distinct. To test this hypothesis, we quantified shape using geometric morphometric analysis and assessed the degree of modularity across functionally important regions. Body shape was highly correlated to phylogenetic relationships, although subfamilies diverged from one another early in their evolutionary history. Within each subfamily, there are various levels of diversification. Surprisingly, we found that the armored catfish body is highly modularized, with varying degrees of integration between each module. This finding suggests the evolution of armored catfish diversification is complex, with morphological evolution influenced by interactions within and between modules. |
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2. 08:15 Phylogenomics of trans-Andean tetras of the genus Hyphessobrycon Durbin 1908 and colonization patterns of Middle America. Diego J. Elías*, Museum of Natural Science, Department of Biological Sciences Louisiana State University, 119 Foster Hall; Caleb D. McMahan , Field Museum of Natural History; Fernando Alda , Department of Biology, Geology and Environmental Science, University of Tennessee at Chattanooga; Carlos García-Alzate , Grupo de Investigación Estudios en Sistemática y Conservación, Universidad del Atlántico-Corporación Universitaria Autónoma del Cauca; Pamela B. Hart , The University of Oklahoma, Sam Noble Museum of Natural Science; Prosanta Chakrabarty , Museum of Natural Science, Department of Biological Sciences, Louisiana State University diegoj.elias@gmail.com
Hyphessobrycon is one of the most species rich genera in the family Characidae, with more than 160 species ranging from Veracruz, Mexico to Argentina. The majority of the diversity of Hyphessobrycon shows a cis-Andean distribution; only nine species are trans-Andean. It is well established that Hyphessobrycon is not monophyletic but has been suggested that natural groups can be identified within the larger Hyphessobrycon species group. In this study, we test the monophyly of trans-Andean species of Hyphessobrycon and investigate the placement of H. compressus, the type species of the genus. We inferred the first phylogenomic hypothesis of trans-Andean Hyphessobrycon that includes nearly complete taxonomic sampling (eight of nine valid species) using ultraconserved elements (UCEs). We analyzed 75%, 90%, and 95% complete data matrices, and inferred phylogenomic hypotheses under concatenation and coalescent approaches. In all cases, we recovered the monophyly of trans-Andean Hyphessobrycon inclusive of H. compressus, strong support for three species groups and evidence of cryptic diversity within H. compressus and H. condotensis. We used our phylogenomic hypothesis to investigate the biogeographic history of Hyphessobrycon in Middle America. Our ancestral range estimation analysis suggests a single event of cis- to trans-Andean colonization followed by stepwise colonization from the Pacific slope of northwestern South America (Chocó block) to northern Middle America (Maya block). Our work supports the recognition of the trans-Andean species as Hyphessobrycon sensu stricto and provides a robust evolutionary template to examine morphological characters that will allow us to better understand the diversity of Hyphessobrycon in Middle America. |
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3. 08:30 Niche overlap? Ecology and morphology of sympatric Rocio (Teleostei: Cichlidae) in Guatemala. César Fuentes-Montejo*, Biological Sciences Deptartment, DePaul University; Windsor Aguirre, Biological Sciences Deptartment, DePaul University; Caleb McMahan, Field Museum of Natural History cefmontejo14@gmail.com
Rocio is a small genus of Neotropical freshwater fishes that is distributed in Atlantic drainages of northern Middle America. Two species in the genus exhibit sympatry in the Lago de Izabal-Río Dulce basin (in Izabal, Guatemala), where one species is endemic (R. spinosissima), while the other only includes this area as part of a larger geographic range (R. octofasciata). Unfortunately, the ecology of these species has been poorly studied. This study sought to determine the ecological and morphological differences between these two closely related sympatric freshwater fishes. We hypothesized that R. octofasciata would exhibit greater ecological and morphological variation, showing an overlap with R. spinosissima. We also hypothesized that morphological divergence would be associated with character displacement. Local-scale environmental data suggest habitat characteristics overlap between the two species, with a greater use of slow-flowing to lentic and poorly oxygenated environments by R. spinosissima, and R. octofasciata inhabiting areas with a larger range of environmental characteristics. Drainage-scale data also indicate that land cover, hydrology, precipitation and temperature largely define the distribution of both species, with some noticeable differences. Additionally, the mean body shape is different between specimens from the two species when they are in sympatry, while specimens from outside of the sympatric area tend to show similar shape characteristics between the two species, following a pattern of character displacement. |
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4. 08:45 Untangling the Phylogenetic Position of the Endemic Cuban Topminnows Genus Girardinus (Cyprinodontiformes: Poeciliidae). Sheila Rodriguez M*, Louisiana State University; Diego J. Elías, Louisiana State University; Prosanta Chakrabarty, Louisiana State University sheilaroma89@gmail.com
Central America and the Greater Antilles have complex geological histories which led to some intricate biogeographic patterns. Poeciliidae is one of the most species-rich freshwater fish families in the region (~ 204 spp.) and has been frequently used to test biogeographic scenarios of colonization. However, our knowledge about the origin and dispersal of many groups within the family is incomplete. One of these groups is the genus Girardinus, which is endemic to Cuba, part of the Greater Antilles. Previous analyzes based on a small number of molecular markers have not been able to resolve the phylogenetic placement of this taxon. In addition, the routes by which the ancestors of Girardinus and its sister genus, Quintana (also endemic to Cuba), took to reach the island remains a mystery. Likewise, the evolutionary history of these topminnows is poorly understood. In this study, we re-examine the phylogenetic position of Girardinus within Poeciliidae using a dataset of ultraconserved elements and mitochondrial loci. We also analyze the relationships among the six species of Girardinus and test hypotheses about their origin and dispersal in the Cuban archipelago. Although the family Poeciliidae is one of the most diverse, well-studied, and widespread in the Neotropics, uncertainty within some clades still challenges our understanding of its evolutionary history; we aim to solve some of those issues with this work. |
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5. 09:00 Functional Trait Evolution in Diadromous Fishes: a Micro- to Macro-Evolutionary Perspective. Darby Finnegan*, Western Michigan University; Joshua Egan, University of Idaho; Devin Bloom, Western Michigan University finnegandl20@gmail.com
The animal tree of life abounds with species that undergo migrations to preferred habitats for feeding or reproduction, typically with high energetic costs. Theory predicts that traits will evolve to minimize energy demands via efficient locomotion. For example, many migratory birds and insects evolved more aerodynamic morphological traits to increase energetic efficiency. Yet, we know little about how aquatic taxa have adapted to optimize cost-benefit trade-offs of migration. Diadromy, an extreme mode of migration in which individuals move between freshwater and marine environments to complete their life cycles, requires both high energy expenditure and the ability to tolerate abiotic and biotic shifts between these ecosystems. Despite the challenges posed by such a life cycle, >300 species of fishes across 28 families have evolved diadromy. We explored how diadromy has shaped locomotory adaptations in Clupeiformes, a group of fishes that has evolved diadromy >12 times and contains the highest proportion of diadromous taxa across fish clades. We analyzed functional locomotory trait data, including fin area, fin moment arms, and caudal fin aspect ratio, across the phylogeny of Clupeiformes, and among diadromous and non-diadromous populations of alewives (Alosa pseudoharengus), to assess whether diadromous taxa have evolved characteristics that reduce energetic costs. Preliminary findings reveal that at both intra- and inter-specific levels, diadromous clupeiform fishes possess a more streamlined, drag reducing body form than non-diadromous fishes, suggesting that enhanced energetic efficiency is critical to the evolution of diadromy in fishes. |