Herbivory promotes dental disparification and macroevolutionary dynamics in grunters (teleostei: Terapontidae), a freshwater adaptive radiation

Trophic shifts into new adaptive zones have played major (although often conflicting) roles in reshaping the evolutionary trajectories of many lineages. We analyze data on diet, tooth, and oral morphology and relate these traits to phenotypic disparification and lineage diversification rates across the ecologically diverse Terapontidae, a family of Australasian fishes. In contrast to carnivores and most omnivores, which have retained relatively simple, ancestral caniniform tooth shapes, herbivorous terapontids appear to have evolved a variety of novel tooth shapes at significantly faster rates to meet the demands of plant-based diets. The evolution of herbivory prompted major disparification, significantly expanding the terapontid adaptive phenotypic continuum into an entirely novel functional morphospace. There was minimal support for our hypothesis of faster overall rates of integrated tooth shape, spacing, and jaw biomechanical evolution in herbivorous terapontids in their entirety, compared with other trophic strategies. There was, however, considerable support for accelerated disparification within a diverse freshwater clade containing a range of specialized freshwater herbivores. While the evolutionary transition to herbivorous diets has played a central role in terapontid phenotypic diversification by pushing herbivores toward novel fitness peaks, there was little support for herbivory driving significantly higher lineage diversification compared with background rates across the family

On trends and patterns in macroevolution: Williston’s law and the branchiostegal series of extant and extinct osteichthyans

The branchiostegal series consists of an alignment of bony elements in the posterior portion of the skull of osteichthyan vertebrates. We trace the evolution of the number of elements in a comprehensive survey that includes 440 extant and 66 extinct species. Using a newly updated actinopterygian tree in combination with phylogenetic comparative analyses, we test whether osteichthyan branchiostegals follow an evolutionary trend under ‘Williston’s law’, which postulates that osteichthyan lineages experienced a reduction of bony elements over time.Results: We detected no overall macroevolutionary trend in branchiostegal numbers, providing no support for ‘Williston’s law’. This result is robust to the subsampling of palaeontological data, but the estimation of the model parameters is much more ambiguous.Conclusions: We find substantial evidence for a macroevolutionary dynamic favouring an ‘early burst’ of trait evolution over alternative models. Our study highlights the challenges of accurately reconstructing macroevolutionary dynamics even with large amounts of data about extant and extinct taxa

Deep reefs are not refugium for shallow-water fish communities in the southwestern Atlantic

Unidad de excelencia María de Maeztu CEX2019-000940-M1. The deep reef refugia hypothesis (DRRH) predicts that deep reef ecosystems may act as refugium for the biota of disturbed shallow waters. Because deep reefs are among the most understudied habitats on Earth, formal tests of the DRRH remain scarce. If the DRRH is valid at the community level, the diversity of species, functions, and lineages of fish communities of shallow reefs should be encapsulated in deep reefs. 2. We tested the DRRH by assessing the taxonomic, functional, and phylogenetic diversity of 22 Brazilian fish communities between 2 and 62 m depth. We partitioned the gamma diversity of shallow (30 m) into independent alpha and beta components, accounted for species' abundance, and assessed whether beta patterns were mostly driven by spatial turnover or nestedness. 3. We recorded 3,821 fishes belonging to 85 species and 36 families. Contrary to DRRH expectations, only 48% of the species occurred in both shallow and deep reefs. Alpha diversity of rare species was higher in deep reefs as expected, but alpha diversity of typical and dominant species did not vary with depth. Alpha functional diversity was higher in deep reefs only for rare and typical species, but not for dominant species. Alpha phylogenetic diversity was consistently higher in deep reefs, supporting DRRH expectations. 4. Profiles of taxonomic, functional, and phylogenetic beta diversity indicated that deep reefs were not more heterogeneous than shallow reefs, contradicting expectations of biotic homogenization near sea surface. Furthermore, pairwise beta-diversity analyses revealed that the patterns were mostly driven by spatial turnover rather than nestedness at any depth. 5. Conclusions. Although some results support the DRRH, most indicate that the shallow-water reef fish diversity is not fully encapsulated in deep reefs. Every reef contributes significantly to the regional diversity and must be managed and protected accordingly

Caracterización taxonómica de la población del pez león <em>Pterois volitans<em> (Linnaeus 1758) (Scorpaenidae) residente en el Caribe colombiano: merística y morfometría

Invasive species are the second main cause of extinction after habitat loss. Lionfish, Pterois volitans (Linnaeus 1758), was seen by the first time in southern Florida in 1985. Since 2000 it has dispersed and established in the eastern coast of the United States and in Bermuda and Bahamas; since 2007 it has expanded through the Caribbean, appearing in oceanic Colombia in 2008 and in continental Colombia in 2009. In order to characterize the lionfish population inhabiting the Colombian Caribbean a literature revision was made as well as collects. Merisitc and morphometric data were taken in the laboratory from a sample of 63 specimens, 36.3-183.0 mm standard length (SL) (from a total of 280 collected individuals). The counts found were: dorsal fin XIII,11 (rarely XIII,12); anal fin III,7 (rarely III,8); pectoral fin 14 (rarely 13). The main measurements (in percentages of SL) found were head length 29,7 - 40,7% and eye diameter 5,6 - 9,1%

Caracterización taxonómica de la población del pez león Pterois volitans (Linnaeus 1758) (Scorpaenidae) residente en el Caribe colombiano: merística y morfometría

Invasive species are the second main cause of extinction after habitat loss. Lionfish, Pterois volitans (Linnaeus 1758), was seen by the first time in southern Florida in 1985. Since 2000 it has dispersed and established in the eastern coast of the United States and in Bermuda and Bahamas; since 2007 it has expanded through the Caribbean, appearing in oceanic Colombia in 2008 and in continental Colombia in 2009. In order to characterize the lionfish population inhabiting the Colombian Caribbean a literature revision was made as well as collects. Merisitc and morphometric data were taken in the laboratory from a sample of 63 specimens, 36.3-183.0 mm standard length (SL) (from a total of 280 collected individuals). The counts found were: dorsal fin XIII,11 (rarely XIII,12); anal fin III,7 (rarely III,8); pectoral fin 14 (rarely 13). The main measurements (in percentages of SL) found were head length 29,7 - 40,7% and eye diameter 5,6 - 9,1%.Las especies invasoras representan una de las principales causas de extinción de la biodiversidad, por lo que son consideradas el segundo motivo, después de la pérdida de hábitat. El pez león Pterois volitans (Linnaeus 1758) fue visto por primera vez al sur de Florida en 1985. Desde 2000 se ha dispersado y establecido en la costa este de Estados Unidos, Bermudas, Bahamas, y desde 2007 se ha expandido por el Caribe, registrándose en localidades oceánicas y continentales de Colombia en 2008 y 2009, respectivamente. Para caracterizar la población residente de P. volitans en aguas del Caribe colombiano se hizo una revisión de literatura y se realizaron colectas de la especie. En el laboratorio se efectuó la caracterización merística y morfométrica de una muestra de la población. Se obtuvieron 280 ejemplares provenientes de la región de Santa Marta, tomándose al azar 63 entre 36,3 y 183,0 mm de longitud estándar (LE), realizándose los conteos y medidas pertinentes; los datos merísticos se presentan siguiendo las convenciones ictiológicas y los morfométricos en porcentajes de LE. Los valores encontrados son: aleta dorsal XIII,11 (raro XIII,12); aleta anal III,7 (raro III,8); aleta pectoral 14 (raro 13); longitud cabeza 29,7 - 40,7%; diámetro ojo: 5,6 - 9,1%

Phylogenetic and Morphologic Analyses of a Coastal Fish Reveals a Marine Biogeographic Break of Terrestrial Origin in the Southern Caribbean

Marine allopatric speciation involves interplay between intrinsic organismal properties and extrinsic factors. However, the relative contribution of each depends on the taxon under study and its geographic context. Utilizing sea catfishes in the Cathorops mapale species group, this study tests the hypothesis that both reproductive strategies conferring limited dispersal opportunities and an apparent geomorphologic barrier in the Southern Caribbean have promoted speciation in this group from a little studied area of the world.Mitochondrial gene sequences were obtained from representatives of the Cathorops mapale species group across its distributional range from Colombia to Venezuela. Morphometric and meristic analyses were also done to assess morphologic variation. Along a approximately 2000 km transect, two major lineages, Cathorops sp. and C. mapale, were identified by levels of genetic differentiation, phylogenetic reconstructions, and morphological analyses. The lineages are separated by approximately 150 km at the Santa Marta Massif (SMM) in Colombia. The northward displacement of the SMM into the Caribbean in the early Pleistocene altered the geomorphology of the continental margin, ultimately disrupting the natural habitat of C. mapale. The estimated approximately 0.86 my divergence of the lineages from a common ancestor coincides with the timing of the SMM displacement at approximately 0.78 my.Results presented here support the hypothesis that organismal properties as well as extrinsic factors lead to diversification of the Cathorops mapale group along the northern coast of South America. While a lack of pelagic larval stages and ecological specialization are forces impacting this process, the identification of the SMM as contributing to allopatric speciation in marine organisms adds to the list of recognized barriers in the Caribbean. Comparative examination of additional Southern Caribbean taxa, particularly those with varying life history traits and dispersal capabilities, will determine the extent by which the SMM has influenced marine phylogeography in the region

Cytogenetic analysis of three sea catfish species (Teleostei, Siluriformes, Ariidae) with the first report of Ag-NOR in this fish family

Despite their ecological and economical importance, fishes of the family Ariidae are still genetically and cytogenetically poorly studied. Among the 133 known species of ariids, only eight have been karyotyped. Cytogenetic analyses performed on Genidens barbus and Sciades herzbergii revealed that both species have 2n = 56 chromosomes and Cathorops aff. mapale has 2n = 52 chromosomes: Genidens barbus has 10 Metacentrics (M), 14 Submetacentrics (SM), 26 Subtelocentrics (ST), and 6 Acrocentrics (A), Sciades herzbergii has 14M, 20SM, 18ST and 4A, whereas Cathorops aff. mapale has 14M, 20SM, and 18ST. The nucleolus organizer regions (NORs) were found in a single chromosome pair on the short arm of a large-sized ST pair in Genidens barbus and on the short arm of a middle-size SM pair in Cathorops aff. mapale. Multiple NORs on the short arms of two large-sized ST pairs were found in Sciades herzbergii. The occurrence of diploid numbers ranging from 2n = 52 through 56 chromosomes and the presence of different karyotypic compositions, besides the number and position of NORs suggest that several numeric and structural chromosome rearrangements were fixed during the evolutionary history of this fish family

Biogeography, habitat transitions and hybridization in a radiation of South American silverside fishes revealed by mitochondrial and genomic RAD data

Rivers and lake systems in the southern cone of South America have been widely influenced by historic glaciations events, carrying important implications on the evolution of aquatic organisms including prompting transitions between marine and freshwater habitats and by triggering hybridization among incipient species via waterway connectivity and stream capture events. Silverside fishes (Odontesthes) in the region comprise a radiation of 19 marine and freshwater species that have been hypothesized on the basis of morphological or mitochondrial DNA data to have either transitioned repeatedly into continental waters from the sea or colonized marine habitats following freshwater diversification. New ddRAD data presented here provide a robust framework to investigate biogeographic history and habitat transitions in Odontesthes. We show that Odontesthes silversides originally diversified in the Pacific but independently colonized the Atlantic three times, producing three independent marine-to-freshwater transitions. Our results also indicate recent introgression of marine mitochondrial haplotypes into two freshwater clades, with more recurring instances of hybridization among Atlantic- vs. Pacific-slope species. In Pacific freshwater drainages, hybridization with a marine species appears to be geographically isolated and may be related to glaciation events. Substantial structural differences of estuarine gradients between these two geographic areas may have influenced the frequency, intensity, and evolutionary effects of hybridization events.Laboratorio de Sistemática y Biología EvolutivaFacultad de Ciencias Naturales y Muse

Evolutionary determinism and convergence associated with water-column transitions in marine fishes

Repeatable, convergent outcomes are prima facie evidence for determinism in evolutionary processes. Among fishes, well-known examples include microevolutionary habitat transitions into the water column, where freshwater populations (e.g., sticklebacks, cichlids, and whitefishes) recurrently diverge toward slender-bodied pelagic forms and deep-bodied benthic forms. However, the consequences of such processes at deeper macroevolutionary scales in the marine environment are less clear. We applied a phylogenomics-based integrative, comparative approach to test hypotheses about the scope and strength of convergence in a marine fish clade with a worldwide distribution (snappers and fusiliers, family Lutjanidae) featuring multiple water-column transitions over the past 45 million years. We collected genome-wide exon data for 110 (∼80%) species in the group and aggregated data layers for body shape, habitat occupancy, geographic distribution, and paleontological and geological information. We also implemented approaches using genomic subsets to account for phylogenetic uncertainty in comparative analyses. Our results show independent incursions into the water column by ancestral benthic lineages in all major oceanic basins. These evolutionary transitions are persistently associated with convergent phenotypes, where deep-bodied benthic forms with truncate caudal fins repeatedly evolve into slender midwater species with furcate caudal fins. Lineage diversification and transition dynamics vary asymmetrically between habitats, with benthic lineages diversifying faster and colonizing midwater habitats more often than the reverse. Convergent ecological and functional phenotypes along the benthic–pelagic axis are pervasive among different lineages and across vastly different evolutionary scales, achieving predictable high-fitness solutions for similar environmental challenges, ultimately demonstrating strong determinism in fish body-shape evolution. This is a postprint of the published article.This research was supported by NSF grants DEB-1932759 and DEB-1929248 to R.B.-R., DEB-1457426 and DEB-1541554 to G.O., DEB-1541552 to C.C.B., and DEB-2015404 to D.A. M.R.-S. was supported by a postdoctoral fellowship from Colciencias (Grant 848-2019). Financial support was provided from the Office of the Vice President for Research and Partnerships and the Office of the Provost, University of Oklahoma.Ye