Phylogeography and evolutionary history of the Panamic Clingfish Gobiesox adustus in the Tropical Eastern Pacific.

The Panamic Clingfish Gobiesox adustus is widely distributed in the Tropical Eastern Pacific (TEP), from the central Gulf of California, Mexico to Ecuador, including the oceanic Revillagigedo Archipelago, and Isla del Coco. This cryptobenthic species is restricted to very shallow rocky-reef habitats. Here, we used one mitochondrial and three nuclear DNA markers from 155 individuals collected across the distribution range of the species in order to evaluate if geographically structured populations exist and to elucidate its evolutionary history. Phylogenetic analyses recovered a monophyletic group, with four well-supported, allopatric subgroups. Each subgroup corresponded to one of the following well-known biogeographic regions/provinces: 1) the Revillagigedo Archipelago, 2) the Cortez + Mexican provinces (Mexico), 3) the Panamic province (from El Salvador to Ecuador), and 4) Isla del Coco. A molecular-clock analysis showed a mean date for the divergence between clade I (the Revillagigedos and Cortez + Mexican provinces) and clade II (Panamic province and Isla del Coco) in the Pliocene, at ca. 5.33 Mya. Within clade I, the segregation between the Revillagigedos and Cortez + Mexican province populations was dated at ca. 1.18 Mya, during the Pleistocene. Within clade II, the segregation between samples of Isla del Coco and the Panamic province samples was dated at ca. 0.77 Mya, during the Pleistocene. The species tree, Bayesian species delimitation tests (BPP and STACEY), the ΦST, AMOVA, and the substantial genetic distances that exist between those four subgroups, indicate that they are independent evolutionary units. These cladogenetic events seem to be related to habitat discontinuities, and oceanographic and geological processes that produce barriers to gene flow for G. adustus, effects of which are enhanced by the intrinsic ecological characteristics of this species.

A multi-locus approach to elucidating the evolutionary history of the clingfish Tomicodon petersii (Gobiesocidae) in the Tropical Eastern Pacific.

Marine species that are widely distributed in the Tropical Eastern Pacific (TEP) has served as a model for studying biogeographic patterns resulting from the effects of intraregional habitat discontinuities and oceanographic processes on the diversification and evolution of cryptobenthic reef fishes. Tomicodon petersii, a clingfish (Gobiesocidae) endemic to the TEP, is found on very shallow rocky reefs from central Mexico to northern Peru, and in the Cocos and Galapagos islands. We evaluated the effect of likely biogeographic barriers in different parts of the TEP on the diversification process of this species. We used one mitochondrial and three nuclear DNA markers from 112 individuals collected across the distribution range of T. petersii. Our phylogenetic results showed the samples constituted a monophyletic group, with three well-supported, allopatric subgroups: in the Mexican province, the Panamic province (from El Salvador to Ecuador), and the Galapagos Islands. The split between the Mexican and more southerly clades was estimated to occur at the end of the Miocene ca. 5.74 Mya, and the subsequent cladogenetic event separating the Galapagos population from the Panamic population at the junction of the Pliocene and Pleistocene, ca. 2.85 Mya. The species tree, Bayesian species delimitation tests (BPP), STACEY, and substantial genetic distances separating these three populations indicate that these three independent evolutionary units likely include two unnamed species. The cladogenetic events that promoted the formation of those genetically differentiated groups are consistent with disruptive effects on gene flow of habitat discontinuities and oceanographic processes along the mainland shoreline in the TEP and of ocean-island isolation, in conjunction with the species intrinsic life-history characteristics.

Ictiofauna de la zona intermareal rocosa del Área de Conservación Guanacaste, Pacífico Norte de Costa Rica: diversidad y aspectos ecológicos y biogeográficos

Introducción: El intermareal rocoso constituye un paisaje marino costero dominante en el Pacífico Tropical Oriental, albergando comunidades biológicas altamente diversas y funcionalmente complejas. El conocimiento sobre la diversidad y los diversos procesos biológicos que ocurren en tales ambientes es, no obstante, bastante limitado a escala regional. Objetivo: Cuantificar, describir y comparar (a escala regional) la diversidad ictiológica asociada al intermareal rocoso del Área de Conservación Guanacaste (ACG), Costa Rica, así como evaluar y discutir algunos patrones biogeográficos y ecológicos. Métodos: Entre 2014 y 2019 se muestrearon un total de 49 pozas de marea en siete ubicaciones dentro del ACG. Se obtuvieron datos sobre diversidad absoluta (presencia/ausencia de especies), además de algunos datos ecológicos (estatus de residencia, estadio(s) de desarrollo, gremio trófico, hábitos de agrupación y crípticos y distribución generalizada) los cuales se compararon con datos publicados de otros estudios/inventarios llevados a cabo en diversas localidades (20) a lo largo de la costa del Pacífico Oriental. Por medio de un análisis de similitud se evaluaron posibles patrones de agrupamiento entre localidades (según su composición de especies) y, bajo una perspectiva biogeográfica, hipótesis previas de regionalización. Resultados: Se registraron un total de 67 especies de peces óseos asociadas al intermareal rocoso del ACG, siendo la localidad con datos publicados, más diversa a nivel del Pacífico Oriental. En el ACG los componentes/categorías transitorio con 30 especies (44.8 %), juveniles con 38 especies (55.9 %), carnívoros con 47 especies (70.1 %), solitarios con 32 especies (47.8 %) y endémico del PTO con 66 especies (98 %), fueron dominantes. A nivel regional se recopilaron datos para un total de 246 especies. Los resultados del análisis de similitud soportaron el esquema de división biogeográfico, definido a priori, a nivel regional, con las localidades ubicadas dentro de las provincias Californiana, Cortez, Mexicana, Panámica y Peruana-Chilena recuperadas como grupos altamente consistentes. Esta estructura es consecuente con el efecto de barreras como las brechas arenosas de Sinaloa y Centroamericana, entre otras, limitando el flujo de especies entre unidades biogeográficas. Conclusiones: El ACG presenta una elevada diversidad ictiológica asociada a su intermareal rocoso producto de una combinación de factores única a nivel regional. Los resultados de este estudio refuerzan además la necesidad de realizar más estudios básicos y aplicados a diferentes escalas local y regional con el objetivo de ayudar a comprender y conocer mejor diversos aspectos clave de la dinámica y procesos físico-químico-biológicos ocurriendo en las zonas intermareales, de su riqueza biológica asociada, de su importancia dentro del paisaje marino-costero como un continuo y de las posibles afectaciones que estos podrían sufrir debido al impacto de las actividades humanas.

Introduction: The rocky intertidal constitutes a dominant coastal seascape in the Eastern Tropical Pacific, harboring highly diverse and functionally complex biological communities. The knowledge about the diversity and the diverse biological processes that occur in such environments is, however, quite limited on a regional scale. Objective: Quantify, describe and compare (on a regional scale) the ichthyological diversity associated with the rocky intertidal zone of the Guanacaste Conservation Area (ACG), Costa Rica, as well as to evaluate and discuss some biogeographic and ecological patterns. Methods: A total of 49 tide pools were sampled between 2014 and 2019, at seven locations within the ACG. Data on absolute diversity (presence/absence of species) were obtained, in addition to some ecological data (residence status, development stage (s), trophic guild, aggregation and cryptic habits and generalized geographic distribution), these data were compared with published records from other surveys/inventories carried out at various locations (20) along the Eastern Pacific coast. Through a similarity analysis, both possible clustering patterns between localities (according to their species composition) and previous hypotheses of regionalization, under a biogeographic perspective, were evaluated. Results: A total of 67 species of bony fish were recorded in the rocky intertidal area of the ACG, being this the most diverse locality (with published data) in the Eastern Pacific. The components/categories "transitory" with 30 species (44.8 %), "juveniles" with 38 species (55.9 %), "carnivores" with 47 species (70.1 %), "solitary" with 32 species (47.8 %) and "endemic to the ETP" with 66 species (98 %), were dominant (in terms of the total number of species) within the ACG. The results of the similarity analysis supported the biogeographic division scheme, defined a priori; with the localities within the Californian, Cortez, Mexican, Panamic and Peruvian-Chilean provinces recovered as highly consistent groups. This structure is consistent with the effect of barriers such as the sandy gaps of Sinaloa and Central America, among others, limiting the flow of species between biogeographic units. Conclusions: The ACG has a high ichthyological diversity associated with its rocky intertidal zone, which is product of a unique combination of factors at the regional level. The results of this study reinforce the need to carry out more basic and applied studies with the aim of helping to better understand and know different key aspects of the dynamics and physical-chemical-biological processes occurring in intertidal zones, of its associated biological diversity, of its importance within the marine-coastal landscape as a continuum and of the possible effects that these environments could suffer due to the impact of human activities.

Independent evolutionary lineage of the clingfish Gobiesox adustus (Gobiesocidae) from Isla del Coco, Costa Rica

Introduction: Isla del Coco is an important protected area for marine fauna in the Eastern Tropical Pacific. In this area, the species that inhabit the intertidal zone have been subject to few studies. One of the species inhabiting these areas is the clingfish Gobiesox adustus (Gobiesocidae). Objective: To analyze for the first time the mitochondrial gene cytochrome oxidase subunit 1 (cox1) of G. adustus' population from Isla del Coco and compare it with those of continental coast of Costa Rica and Ecuador. Methods: We constructed a haplotype network for these samples. Genetic diversity, distance and structure were calculated by several software. The historical demography of Isla del Coco samples was assessed with the method Bayesian skyline plot as implemented in BEAST2. Results: The samples segregate into three haplogroups: one consisting of the Isla del Coco samples, a second consisting of a subset of the Ecuador samples, and a third consisting of Costa Rica and the remaining Ecuador samples. The genetic distances between the three haplogroups range between 1.6% and 2.1% (uncorrected p-distance), and pairwise ΦST and AMOVA results between the three haplogroups show high and significant values. Conclusions: The Isla del Coco haplogroup showed a Pleistocene population growth, which agrees with demographic patterns found in other marine organisms. The history of isolation of the G. adustus population from Isla del Coco demonstrates the evolutionary independence of this population.

Introducción: Isla del Coco es un área protegida importante para la fauna marina en el Pacifico Oriental Tropical. En esta área, las especies que habitan la zona intermareal han sido objeto de pocos estudios. Una de las especies que habitan en estas áreas es el clingfish Gobiesox adustus (Gobiesocidae). Objetivo: Analizar por primera vez el gen mitocondrial citocromo oxidasa sub unidad 1 (cox1) de poblaciones de Isla del Coco y compararlo con las de la zona continental de Costa Rica y Ecuador. Métodos: Se construyó una red de haplotipos. La diversidad, la distancia y la estructura genética fueron calculadas por diversos programas. La demografía histórica de las muestras de Isla del Coco fue evaluada con el método Bayesian skyline plot implementado en BEAST2. Resultados: Las muestras se agruparon en tres haplogrupos: en un haplogrupo se incluyó a los individuos de Isla del Coco, otro haplogrupo integró las muestras de Ecuador y un tercer grupo incluyó las muestras restantes de Costa Rica y Ecuador. Las distancias genéticas entre los tres haplogrupos oscilan entre 1.6% y 2.1% (p-distancia, no corregida), las distancias ΦST y los resultados de AMOVA entre los tres haplogrupos muestran valores altos y significativos. Conclusiones: El haplogrupo de Isla del Coco mostró un crecimiento poblacional datado en el Pleistoceno, coincidiendo con la demografía poblacional encontrada en otros organismos marinos. La historia de aislamiento de la población de G. adustus de Isla del Coco demostró la independencia evolutiva de esta población.

Annotated checklist of the coastal ichthyofauna from Michoacán State, Mexico.

This study is the first to complete an intensive and comprehensive list of the ichthyofauna of nearly all ecosystems of the Michoacán coast, Mexico. The resulting systematic checklist, supplemented with information from the literature and scientific collections, comprises 440 species belonging to two classes, 31 orders, 104 families, and 264 genera. The families with the highest number of species were Sciaenidae (30 spp.), Carangidae (26), Haemulidae (24), Serranidae (21), Paralichthyidae, and Gobiidae (13). Of the total species list, 134 represent first records for the Michoacán State, and one is a first record for Mexico. The results expand the number of known fish species of the Michoacán coast by almost one third and will help to develop conservation and management plans for this coastal zone.