Papers by Gastón Aguilera
Ecología Austral
Ante la crisis global de pérdida de biodiversidad y deterioro de los ecosistemas, las áreas natur... more Ante la crisis global de pérdida de biodiversidad y deterioro de los ecosistemas, las áreas naturales protegidas tienen un rol preponderante como herramienta de manejo. Sin embargo, la mayoría se basa sobre criterios terrestres, mientras que los organismos de agua dulce son los más amenazados en cuanto a su conservación. En este trabajo se analiza el efecto de protección del Parque Nacional El Rey y de una crecida estival del río Popayán, de la cuenca del río Bermejito, sobre las poblaciones de peces de interés pesquero (el dorado [Salminus brasiliensis], el sábalo [Prochilodus lineatus] y la boga [Megaleporinus spp.]). Se realizaron estimaciones de abundancia y de talla mediante censos visuales antes y después al evento de crecida, y también dentro y en los límites del área protegida, en un contexto de presión de pesca por parte de pescadores furtivos. No se registró un efecto significativo de la crecida sobre las especies en estudio, pero sí del efecto del área protegida: en su in...
Animal genitalia vary considerably across taxa, with divergence in many morphological traits incl... more Animal genitalia vary considerably across taxa, with divergence in many morphological traits including striking departures from symmetry. Different mechanisms have been proposed to explain this diversity, mostly assuming that at least some of the phenotypic variation is heritable. However, heritability of the direction of genital asymmetry has been rarely determined. Anablepids are internally fertilizing fish where the anal fin of males has been modified into an intromittent organ that transfers sperm into the gonopore of females. Males of anablepid fishes exhibit asymmetric genitalia and both, left- and right-sided individuals are commonly found at similar proportions within populations (i.e. antisymmetry). Although this polymorphism was described over a century ago, there have been no attempts to determine if genital asymmetry has a genetic basis and whether the different morphs are accumulating genetic differences, as might be expected since in some species females have also asymmetric gonopores and thereby can only be fertilized by compatible asymmetric males. We address this issue by combining breeding experiments with genome-wide data (ddRAD markers) in representative species of the two Anablepid genera with asymmetric genitalia: <i>Anableps</i> and <i>Jenynsia</i>. Breeding experiments showed that all offspring were asymmetric, but their morphotype (i.e. right or left-sided) was independent of parental morphotype, implying that the direction of asymmetry does not have a strong genetic component. Consistent with this conclusion, association analyses based on approximately 25 000 SNPs did not identify markers significantly associated with the direction of genital asymmetry and there was no evidence of population structure between left- and right-sided individuals. These results suggest that the direction of genital asymmetry in Anablepid fishes might be stochastic, a commonly observed pattern in species with antisymmetry in morphological traits.
Neotropical Ichthyology, 2019
A new species of Farlowella is described from the Bermejo River basin, in Salta and Jujuy provinc... more A new species of Farlowella is described from the Bermejo River basin, in Salta and Jujuy provinces, northwestern Argentina. The new species belongs to the Farlowella nattereri species group. The new species is diagnosed by the following combination of characters: marbled rostrum, five rows of lateral plates series, relatively short snout (snoutmouth length less than 50.0% of head length), complete half-moon shaped spot on caudal fin, and short predorsal distance (37.8-41.8% of standard length).
Check List, Aug 26, 2016
Hypostomus cochliodon Kner, 1854 had been recorded from Paraguay and Paraná rivers in Argentina. ... more Hypostomus cochliodon Kner, 1854 had been recorded from Paraguay and Paraná rivers in Argentina. We recorded for the first time specimens of H. cochliodon to the Bermejo River basin. It is also the first record of this species to Salta province, Argentina.
Check List, Oct 1, 2014
This research was carried out under licending permit Expediente 119-10452/05, Cde. 3, Resolucion ... more This research was carried out under licending permit Expediente 119-10452/05, Cde. 3, Resolucion 119.
PLOS ONE, Jul 10, 2019
Freshwater sulfide springs have extreme environmental conditions that only few vertebrate species... more Freshwater sulfide springs have extreme environmental conditions that only few vertebrate species can tolerate. These species often develop a series of morphological and molecular adaptations to cope with the challenges of life under the toxic and hypoxic conditions of sulfide springs. In this paper, we described a new fish species of the genus Jenynsia, Anablepidae, from a sulfide spring in Northwestern Argentina, the first in the family known from such extreme environment. Jenynsia sulfurica n. sp. is diagnosable by the lack of scales on the pre-pelvic area or the presence of a single row of scales, continuous or not, from the isthmus to the bases of the pelvic fins. Additionally, it presents a series of morphological and molecular characteristics that appear convergent with those seen in other fish species (e.g., Poeciliids) inhabiting sulfide springs. Most notably, J. sulfurica has an enlarged head and postorbital area compared to other fish of the genus and a prognathous lower jaw with a hypertrophied lip, thought to facilitate respiration at the air-water interface. Analyses of cox1 sequence showed that J. sulfurica has two unique mutations resulting in amino acid substitutions convergent to those seen in Poeciliids from sulfide springs and known to provide a physiological mechanism related to living in sulfide environments. A phylogenetic analysis, including molecular and morphological characters, placed J. sulfurica as sister taxa to J. alternimaculata, a species found in nearby, non-sulfide habitats directly connected to the sulfide springs. Thus, it can be inferred that the selection imposed by the presence of H 2 S has resulted in the divergence between these two species and has potentially served as a barrier to gene flow.
Proceedings of The Royal Society B: Biological Sciences, May 11, 2022
Phylogenetic comparative studies suggest that the direction of deviation from bilateral symmetry ... more Phylogenetic comparative studies suggest that the direction of deviation from bilateral symmetry (sidedness) might evolve through genetic assimilation; however, the changes in sidedness inheritance remain largely unknown. We investigated the evolution of genital asymmetry in fish of the family Anablepidae, in which males' intromittent organ (the gonopodium, a modified anal fin) bends asymmetrically to the left or the right. In most species, males show a 1 : 1 ratio of left-to-right-sided gonopodia. However, we found that in three species left-sided males are significantly more abundant than right-sided ones. We mapped sidedness onto a new molecular phylogeny, finding that this left-sided bias likely evolved independently three times. Our breeding experiment in a species with an excess of left-sided males showed that sires produced more left-sided offspring independently of their own sidedness. We propose that sidedness might be inherited as a threshold trait, with different thresholds across species. This resolves the apparent paradox that, while there is evidence for the evolution of sidedness, commonly there is a lack of support for its heritability and no response to artificial selection. Focusing on the heritability of the left : right ratio of offspring, rather than on individual sidedness, is key for understanding how the direction of asymmetry becomes genetically assimilated.
Papers in palaeontology, Dec 21, 2017
Two new genera and species of Cyprinodontiformes from the Miocene of Tucumán, Argentina, are desc... more Two new genera and species of Cyprinodontiformes from the Miocene of Tucumán, Argentina, are described: Tucmanableps cionei and Sachajenynsia pacha. Both exhibit sexual dimorphism, indicated by the modification of the male anal fin into an intromittent organ; tricuspid teeth in the jaws; abdominal pelvic fins and other features that demonstrate a relationship with the family Anablepidae. Males of Sachajenynsia pacha gen. et sp. nov. present modifications of the anal fin, herein interpreted as an incipient gonopodium, whereas the anal fin of Tucmanableps cionei gen. et sp. nov. is modified into a complex gonopodium with a median distal plate, which is unique among the Anablepidae. In extant genera of the family, modification of the anal fin into an intromittent organ is related to internal fertilization; this condition is inferred for S. pacha but was clearly the reproductive mode of T. cionei. In our phylogenetic analysis, S. pacha is recovered as the sister group of all anablepids with evident internal fertilization, while T. cionei forms a clade with Anableps species. The occurrence of two new anablepid genera showing distinct and unique morphologies suggests that the fossil diversity of the Anablepidae may be higher than the extant one. Also, the new taxa were found in open lake deposits with coastal and inner lake sediments of the Río Salí Formation associated with the Miocene Entrerrian–Paranense Marine Ingression, supporting the idea that coastal environments and brackish waters are related to the generic diversification of the Anablepidae, as was suggested for the species of Jenynsia.
Current Zoology, Apr 26, 2019
Asymmetries in bilateral organisms attract a lot of curiosity given that they are conspicuous dep... more Asymmetries in bilateral organisms attract a lot of curiosity given that they are conspicuous departures from the norm. They allow the investigation of the integration at different levels of biological organization. Here we study whether and how behavioral and asymmetrical anatomical traits coevolved and work together. We ask if asymmetry is determined locally for each trait or at a whole individual level in a species bearing conspicuous asymmetrical genitalia. Asymmetric genitalia evolved in many species; however, in most cases the direction of asymmetry is fixed. Therefore, it has been rarely determined if there is an association between the direction of asymmetry in genitalia and other traits. In onesided livebearer fish of the genus Jenynsia (Cyprinodontiformes, Anablepidae), the anal fin of males is modified into a gonopodium, an intromittent organ that serves to inseminate females. The gonopodium shows a conspicuous asymmetry, with its tip bending either to the left or the right. By surveying 13 natural populations of Jenynsia lineata, we found that both genital morphs are equally common in wild populations. In a series of experiments in a laboratory population, we discovered asymmetry and lateralization for multiple other traits; yet, the degree of integration varied highly among them. Lateralization in exploratory behavior in response to different stimuli was not associated with genital morphology. Interestingly, the direction of genital asymmetry was positively correlated with sidedness of mating preference and the number of neuromasts in the lateral line. This suggests integration of functionally linked asymmetric traits; however, there is no evidence that asymmetry is determined at the whole individual level in our study species.
Proceedings of The Royal Society B: Biological Sciences, Jul 8, 2020
Animal genitalia vary considerably across taxa, with divergence in many morphological traits, inc... more Animal genitalia vary considerably across taxa, with divergence in many morphological traits, including striking departures from symmetry. Different mechanisms have been proposed to explain this diversity, mostly assuming that at least some of the phenotypic variation is heritable. However, heritability of the direction of genital asymmetry has been rarely determined. Anablepidae are internally fertilizing fish where the anal fin of males has been modified into an intromittent organ that transfers sperm into the gonopore of females. Males of anablepid fishes exhibit asymmetric genitalia, and both left-and right-sided individuals are commonly found at similar proportions within populations (i.e. antisymmetry). Although this polymorphism was described over a century ago, there have been no attempts to determine if genital asymmetry has a genetic basis and whether the different morphs are accumulating genetic differences, as might be expected since in some species females have also asymmetric gonopores and thereby can only be fertilized by compatible asymmetric males. We address this issue by combining breeding experiments with genome-wide data (ddRAD markers) in representative species of the two anablepid genera with asymmetric genitalia: Anableps and Jenynsia. Breeding experiments showed that all offspring were asymmetric, but their morphotype (i.e. right-or left-sided) was independent of parental morphotype, implying that the direction of asymmetry does not have a strong genetic component. Consistent with this conclusion, association analyses based on approximately 25 000 SNPs did not identify markers significantly associated with the direction of genital asymmetry and there was no evidence of population structure between leftand right-sided individuals. These results suggest that the direction of genital asymmetry in anablepid fishes might be stochastic, a commonly observed pattern in species with antisymmetry in morphological traits.
Fil: Cancino, Fabiana. Fundacion Miguel Lillo. Direccion de Zoologia. Instituto de Vertebrados. S... more Fil: Cancino, Fabiana. Fundacion Miguel Lillo. Direccion de Zoologia. Instituto de Vertebrados. Seccion Ictiologia; Argentina
Zoosystematics and Evolution, Sep 8, 2022
A new diagnosis and a new classification of Heptapterus are provided and a new species, H. carmel... more A new diagnosis and a new classification of Heptapterus are provided and a new species, H. carmelitanorum, is described. Heptapterus is diagnosed by the following character combination: adipose fin confluent with the caudal fin; non-bifurcate caudal fin; anal-fin insertion posterior to vertical through adipose-fin insertion; 10-23 anal-fin rays; anal fin not confluent with caudal fin; and extremely elongate body, with a head length of 16.1-24.9%SL. Species included in Heptapterus are H. borodini, H. carmelitanorum, H. carnatus, H. exilis, H. hollandi, H. mandimbusu, H. mbya, H. mustelinus, H. ornaticeps, and H. qenqo. Some of the character states diagnosing H. carmelitanorum among its congeners are the anal-fin insertion less than one eye diameter posterior to a vertical through the adipose-fin insertion (vs. more than one eye diameter in all congeners); the isognathous mouth (vs. slightly to moderately retrognathous, except H. borodini); and the keel formed by ventral procurrent caudal-fin rays shallow, far from reaching anal-fin base (vs. keel formed by ventral procurrent caudal-fin rays deep, continuing almost to the anal-fin base, except in H. borodini and H. hollandi).
Journal of Fish Biology, Sep 12, 2022
Specimens of Imparfinis were recently collected in northwestern Argentina from the Bermejo River ... more Specimens of Imparfinis were recently collected in northwestern Argentina from the Bermejo River basin (Salta and Jujuy Provinces), del Valle River (Salta Province) and Horcones River (Santiago del Estero Province). An integrative approach to taxonomy, combining a detailed morphological study and molecular phylogenetic analyses, was applied in order to determine the species identity of these specimens. A principal components analysis of morphological data clustered the specimens from northwestern Argentina and from the Amazon basin, indicating a close morphological resemblance. Also, a molecular phylogenetic analysis showed populations of I. guttatus from Argentina and Peru forming a clade. According to the conducted haplotype network analysis these populations are distinct in two mutations. Thus, in absence of morphological or molecular data indicating the contrary, the combined method supports the identity of the specimens from the tributaries of the Paraguay River in Argentina as Imparfinis guttatus, whose type locality is in the upper Beni River basin in Bolivia. This contribution is also the first record for this species from Argentina. The disjunct distribution of I. guttatus provides new evidence reinforcing the hypothesis for the origin of the Paraguayan ichthyofauna. We also provide an approach to the phylogenetic relationships of Imparfinis in Heptapteridae. We applied an integrative approach to taxonomy, including morphological, phylogenetic and haplotype network analyses in order to assess the specific status of specimens of Imparfinis collected in Argentina. Theses analyses allows us to identify the specimens as This article is protected by copyright. All rights reserved. Imparfinis guttatus, expanding its distributional range. The disjunct distribution shown by I. guttatus represents new evidence on the origin of Paraguayan ichthyofauna. Also we provide the most comprehensive phylogenetic analysis of the relationships of Imparfinis in Heptapteridae.
Aphyocharax anisitsi is recorded for the first time from the upper Bermejo River, Argentina, in t... more Aphyocharax anisitsi is recorded for the first time from the upper Bermejo River, Argentina, in the provinces of Salta and Jujuy. This represents a range extension of the known distribution of approximately 600 km. Also, collection specimens of A. dentatus from this area are cited for first time. Resumen Aphyocharax anisitsi es registrado por primera vez en la Cuenca alta del Río Bermejo, Argentina, en las provincias de Salta y Jujuy. Esto representa una extensión de la distribución conocida de aproximadamente 600 km. Además, se cita material de colección de A. dentatus para el área por primera vez.
Revista del Museo Argentino de Ciencias Naturales, 2016
Hypostomus boulengeri (Eigenmann and Kennedy, 1903) is a poorly known species recorded from the P... more Hypostomus boulengeri (Eigenmann and Kennedy, 1903) is a poorly known species recorded from the Paraguay and Paraná River basins. In this work we report the occurrence of this species in the Bermejo River basin for the first time, representing a distribution range extension of more than 600 km.
Revue Suisse De Zoologie, 2004
A new species of Astyanax (Characiformes, Characidae) from the upper río Bermejo basin, Salta, Ar... more A new species of Astyanax (Characiformes, Characidae) from the upper río Bermejo basin, Salta, Argentina.-Astyanax latens sp. n., from the Bermejo river basin, is described in this paper. Astyanax latens is diagnosed by a combination of characters: somewhat rhomboidal body; presence of24-29 branched anal fin rays; 1-4 maxillary teeth; long pectoral fins (23.2-26.6 % of SL) always reaching one third of pelvic fin; long pelvic fins (17.6-22.0 % of SL) always surpassing anal fin origin; anal fin base long (32.3-36.7 % of SL); 26-27 gill rakers on first branchial arch; lateral band extremely narrow; one large vertically elongated humeral spot and a second one very faint; relatively shallow caudal pedunc1e(10.0-11.4 % SL); fifth tooth of inner premaxillary series very small and scarcely posterior to main series; origin of anal fin below dorsal fin.
Acta Zoológica Lilloana
Parque Nacional Aconquija es el único parque nacional de la provincia de Tucumán, Argentina, y un... more Parque Nacional Aconquija es el único parque nacional de la provincia de Tucumán, Argentina, y uno de los más importantes del noroeste y de todo el país, debido a que es el parque con mayor gradiente altitudinal de Argentina (Administración de Parques Nacionales, 2023), que va desde los 511 hasta los 5450 m s.n.m. Dado que este parque nacional es de reciente creación, la mayor parte de su territorio aún no ha sido investigado en cuanto a su diversidad de especies. Los cuerpos de agua de esta zona están representados por ríos y arroyos de montaña pertenecientes a la cuenca del Salí-Dulce. El presente estudio proporciona una lista de especies de peces de agua dulce presentes en el Parque Nacional Aconquija. La investigación se llevó a cabo en cuatro áreas del parque nacional, es el primer abordaje para estudiar la ictiofauna del Parque, analizamos 427 individuos distribuidos en 5 órdenes, 10 familias y 20 especies. Cada una de las especies tiene ejemplares testigo depositados en la co...
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Papers by Gastón Aguilera