Phylogeography, colonization and population history of the Midas cichlid species complex (Amphilophus spp.) in the Nicaraguan crater lakes

<p>Abstract</p> <p>Background</p> <p>Elucidation of the mechanisms driving speciation requires detailed knowledge about the phylogenetic relationships and phylogeography of the incipient species within their entire ranges as well as their colonization history. The Midas cichlid species complex <it>Amphilophus </it>spp. has been proven to be a powerful model system for the study of ecological specialization, sexual selection and the mechanisms of sympatric speciation. Here we present a comprehensive and integrative phylogeographic analysis of the complete Midas Cichlid species complex in Nicaragua (> 2000 individuals) covering the entire distributional range, using two types of molecular markers (the mitochondrial DNA control region and 15 microsatellites). We investigated the majority of known lake populations of this species complex and reconstructed their colonization history in order to distinguish between alternative speciation scenarios.</p> <p>Results</p> <p>We found that the large lakes contain older and more diverse Midas Cichlid populations, while all crater lakes hold younger and genetically less variable species assemblages. The large lakes appear to have repeatedly acted as source populations for all crater lakes, and our data indicate that faunal exchange among crater lakes is extremely unlikely. Despite their very recent (often only a few thousand years old) and common origin from the two large Nicaraguan lakes, all crater lake Midas Cichlid radiations underwent independent, but parallel, evolution, and comprise distinct genetic units. Indeed several of these crater lakes contain multiple genetically distinct incipient species that most likely arose through sympatric speciation. Several crater lake radiations can be traced back to a single ancestral line, but some appear to have more than one founding lineage. The timing of the colonization(s) of each crater lake differs, although most of them occurred more (probably much more) recently than 20,000 years ago.</p> <p>Conclusion</p> <p>The genetic differentiation of the crater lake populations is directly related to the number of founding lineages, but independent of the timing of colonization. Interestingly, levels of phenotypic differentiation, and speciation events, appeared independent of both factors.</p

Depth-dependent abundance of Midas Cichlid fish ( Amphilophus spp: ) in two Nicaraguan crater lakes

The Midas Cichlid species complex (Amphilophus spp.) in Central America serves as a prominent model system to study sympatric speciation and parallel adaptive radiation, since small arrays of equivalent ecotype morphs have evolved independently in different crater lakes. While the taxonomy and evolutionary history of the different species are well resolved, little is known about basic ecological parameters of Midas Cichlid assemblages. Here, we use a line transect survey to investigate the depth-dependent abundance of Amphilophus spp. along the shores of two Nicaraguan crater lakes, Apoyo and Xiloá. We find a considerable higher density of Midas cichlids in Lake Xiloá as compared to Lake Apoyo, especially at the shallowest depth level. This might be due to the higher eutrophication level of Lake Xiloá and associated differences in food availability, and/or the presence of a greater diversity of niches in that lake. In any case, convergent forms evolved despite noticeable differences in size, age, eutrophication level, and carrying capacity. Further, our data provide abundance and density estimates for Midas Cichlid fish, which serve as baseline for future surveys of these ecosystems and are also relevant to past and future modeling of ecological speciatio

I Jornadas Científicas del Museo Nacional de Ciencias Naturales

I Jornadas Científicas del Museo Nacional de Ciencias Naturales, celebradas el 21-22 Febrero 2017, en el Museo Nacional de Ciencias Naturales (Madrid)El objetivo de las I Jornadas Científicas del Museo Nacional de Ciencias Naturales es dar a conocer las diferentes líneas de investigación que están realizando los distintos Departamentos de este Centro, además de dar la oportunidad de conocerse y facilitar la interacción entre todos. Las jornadas constan de 26 charlas (con sus presentaciones) y en principio, son representativas de todos los departamentos de forma equitativa de acuerdo con el número de miembros de cada uno de los participantes. Además dos o tres charlas "plenarias" de interés general. Se da prioridad a participar a los jóvenes investigadores, estudiantes de doctorado o jóvenes postdoctorandos. Participación de miembros de: Departamento de Biogeografía y Cambio Global, Dept. Ecología Evolutiva, Dept. Geología, Dept. Biodiversidad y Biología Evolutiva, Dept. Biogeoquímica y Ecología Microbiana, Dept. Paleobiología.01 Pequeña historia. 02 Programa de las Jornadas. 03 Libro de resumenes. 04 Cartel anunciador. 05 Menus de desayuno y almuerzo. 06 Balance de las Jornadas. 07 AgradecimientosPresentaciones disponibles: Álvarez-Cobelas: "Los científicos hispanos como insectos sociales?".-- Mikel Calle: "Cuando el río suena... agua lleva. Caracterizando la dinámica de los cauces efímeros mediterráneos”.-- María Cristina Casero: “"Aquí no hay quien viva: Microorganismos litobiónticos en el desierto de Atacama".-- Cepeda, Diego; Soler-Hurtado, M. Mar; Lattig, Patricia: "Un océano de gusanos marinos: la importancia de conocer la biodiversidad de anélidos asociados a corales".-- Flores, Omar; Rey, Ana; Curiel Yuste, Jorge; Valladares Ros, Fernando: “Modelización de la descomposición de la hojarasca en climas áridos”.-- Forner, Alicia; Aranda, Ismael; Valladares Ros, Fernando: “Árboles mediterráneos en la cuerda floja: sequías extremas, ¿un crimen con atenuantes?”.-- García-Ángulo, Daniel: “Ojos que no ven… Efecto del cambio climático y del manejo histórico de los encinares en el suelo bajo nuestros pies”.- García Morato, Sara: “Hienas, humanos y micromamíferos”.-- García-Tabernero, Antonio: “Aplicaciones de antropología virtual: colecciones virtuales y paleoneurología”.-- Garrido-Benavent, Isaac: Estudios filogeográficos de dos especies de hongos liquenizados muestran orígenes distintos de la biota liquénica antártica".-- Garrido, Fernando; García-Guinea, Javier; Gómez-González, Miguel A.: Presencia de arsénico en suelos contaminados de la provincia de Madrid.-- Gaspar, Leticia: “Técnicas radiométricas en el estudio de la erosión y la redistribución del suelo”.-- Doadrio, Ignacio; Pardos Blas, José Ramón: Desenredando el género Gambusia (Poeciliidae) en el noreste de México.-- Riesco López, Alberto; Bastir, Markus: Morfología virtual en 3D del Megatherium americanum del MNCNPeer reviewe

Iodine Atoms: A New Molecular Feature for the Design of Potent Transthyretin Fibrillogenesis Inhibitors

The thyroid hormone and retinol transporter protein known as transthyretin (TTR) is in the origin of one of the 20 or so known amyloid diseases. TTR self assembles as a homotetramer leaving a central hydrophobic channel with two symmetrical binding sites. The aggregation pathway of TTR into amiloid fibrils is not yet well characterized but in vitro binding of thyroid hormones and other small organic molecules to TTR binding channel results in tetramer stabilization which prevents amyloid formation in an extent which is proportional to the binding constant. Up to now, TTR aggregation inhibitors have been designed looking at various structural features of this binding channel others than its ability to host iodine atoms. In the present work, greatly improved inhibitors have been designed and tested by taking into account that thyroid hormones are unique in human biochemistry owing to the presence of multiple iodine atoms in their molecules which are probed to interact with specific halogen binding domains sitting at the TTR binding channel. The new TTR fibrillogenesis inhibitors are based on the diflunisal core structure because diflunisal is a registered salicylate drug with NSAID activity now undergoing clinical trials for TTR amyloid diseases. Biochemical and biophysical evidence confirms that iodine atoms can be an important design feature in the search for candidate drugs for TTR related amyloidosis

Adaptive phenotypic plasticity in the Midas cichlid fish pharyngeal jaw and its relevance in adaptive radiation

Phenotypic evolution and its role in the diversification of organisms is a central topic in evolutionary biology. A neglected factor during the modern evolutionary synthesis, adaptive phenotypic plasticity, more recently attracted the attention of many evolutionary biologists and is now recognized as an important ingredient in both population persistence and diversification. The traits and directions in which an ancestral source population displays phenotypic plasticity might partly determine the trajectories in morphospace, which are accessible for an adaptive radiation, starting from the colonization of a novel environment. In the case of repeated colonizations of similar environments from the same source population this "flexible stem" hypothesis predicts similar phenotypes to arise in repeated subsequent radiations. The Midas Cichlid (Amphilophus spp.) in Nicaragua has radiated in parallel in several crater-lakes seeded by populations originating from the Nicaraguan Great Lakes. Here, we tested phenotypic plasticity in the pharyngeal jaw of Midas Cichlids. The pharyngeal jaw apparatus of cichlids, a second set of jaws functionally decoupled from the oral ones, is known to mediate ecological specialization and often differs strongly between sister-species. We performed a common garden experiment raising three groups of Midas cichlids on food differing in hardness and calcium content. Analyzing the lower pharyngeal jaw-bones we find significant differences between diet groups qualitatively resembling the differences found between specialized species. Observed differences in pharyngeal jaw expression between groups were attributable to the diet's mechanical resistance, whereas surplus calcium in the diet was not found to be of importance. The pharyngeal jaw apparatus of Midas Cichlids can be expressed plastically if stimulated mechanically during feeding. Since this trait is commonly differentiated - among other traits - between Midas Cichlid species, its plasticity might be an important factor in Midas Cichlid speciation. The prevalence of pharyngeal jaw differentiation across the Cichlidae further suggests that adaptive phenotypic plasticity in this trait could play an important role in cichlid speciation in general. We discuss several possibilities how the adaptive radiation of Midas Cichlids might have been influenced in this respect

Molecular characterization of MHC class IIB genes of sympatric Neotropical cichlids

Ministerio de Economía y Competitividad del Gobierno de España, Programa de Formación de Personal Investigador FPI BES-2011-047645 to MJH, Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia Proyecto CGL 2010-16103 to MB. This project was further enabled through two German Science Foundation grants to CE (DFG, EI841/4-1 and EI841/6-1) both part of the SPP 1399 priority programme on “host-parasite interactions”

The role of gill rakers in the adaptation and habitat partitioning of Nicaraguan crater lake cichlid fishes

The coexistence of species is facilitated by niche partitioning. Resource competition is a major cause of phenotypic differentiation.The major axes of differentiation in closely related species occur along the two ecological dimensions habitat and diet. Adaptive radiations typically follow these axes of variation. Some of the most important traits in the radiations of freshwater fish are body size, body shape, and a few trophic features such as mouth position, teeth type or gill rakers. In some of the most famous temperate freshwater radiations (i.e., sticklebacks, whitefish) gill rakers play a pivotal role in the adaptation to novel prey types. Cichlids are the most famous textbook examples of fast and divergent adaptive radiations. Often species differ in adaptation to alternative prey types associated to particular trophic morphologies. Pharyngeal jaw shape, oral and pharyngeal teeth and mouth position are the main traits typically studied in cichlid radiations. Gill rakers have however rarely been consider when trying to understand cichlid adaptation to the environment. Here we assess the variation of gill rakers in the cichlid assemblage inhabiting the Nicaraguan large and crater lakes. We found marked differences among species, and found interesting correlations between gill raker traits and environmental features demonstrating their role in adaptation and diversification

Host-parasite interactions in crater lake cichlids

Convergence Symposium (Hegne 1-5 June 2022)Animals and plants are no longer viewed as autonomous entities, but rather as holobionts, composed of the host plus macro and microorganisms coexisting with them. Coexistence and adaptation to this biotic environment has consequences in many fundamental aspects of host¿s form, function, and fitness, including behavior, sociality and the origin of species. Host-parasite co-evolution is one of the most important generators of biological diversity. We studied the recent adaptive radiations of the Neotropical Midas cichlid in the Nicaraguan crater lakes, and their associated parasite communities to investigate how changes in parasite communities induce changes in the fish physiology and immune system. We discuss how these changes might start, maintain or enhance populations and species differentiation