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![-Acanthemblemaria balanoru m, El Pelado Island, Guayas, Ecuador. Head detail showing the specific cranial spination. HL = 10.2 mm. [Détail de la tête montrant l'ornementation spécifique du crâne.]](profile/Philippe-Bearez/publication/287575341/figure/fig2/AS:670049345998876@1536763621920/Acanthemblemaria-balanoru-m-El-Pelado-Island-Guayas-Ecuador-Head-detail-showing-the.png)
-Acanthemblemaria balanoru m, El Pelado Island, Guayas, Ecuador. Head detail showing the specific cranial spination. HL = 10.2 mm. [Détail de la tête montrant l'ornementation spécifique du crâne.]
Contexts in source publication
Context 1
... examined. -MNHN 2004-0540, 4 specimens 32-44.5 mm SL (37-51 mm TL), collected on 21/09/2003, 8-12 m, Islet El Pelado, San Pedro, Guayas, Ecuador (1°56'S, 80°47'W), (Fig. 2). D i s t r i b u t i o n. -Tropical eastern Pacific endemic chaenopsid species, known from the Gulf of California to southern Mexico, Panama, and Gorgona Island (Hastings and Robertson, 1999). Range is herein extended to southern Ecuador. D e s c r i p t i o n. -The genus A c a n t h e m b l e m a r i a is the most char- acteristic ...
Context 2
... family and its members are well known for their prominent cranial spination. The cranial spines and pore patterns of A. balanoru m easily distinguished it from other members of the genus. The frontal bones of this species have con- spicuous high and thick spines on head, often club-shaped in larg e individuals (Rosenblatt and McCosker, 1988: Fig. ...
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... (a) Study organism L. dalli is a small (<45 mm standard length, SL), marine fish that inhabits rocky reefs in the Pacific Ocean, from Morro Bay, California as far south as the Galapagos Islands, Ecuador (Miller and Lea 1972;B earez et al. 2007). The reproductive season lasts approximately from April to September, and females lay multiple clutches throughout the season. ...
Both individual sex and population sex ratio can affect lifetime reproductive success. As a result, multiple mechanisms have evolved to regulate sexual phenotype, including adult sex change in fishes. While adult sex change is typically socially regulated, few studies focus on the non- chromosomal mechanisms regulating primary sex allocation. We investigated primary sex determination in the bluebanded goby (Lythrypnus dalli), a bidirectionally sex-changing fish. Of the studies investigating primary sex determination in species with adult sex change, this is the first to incorporate the roles of social status and size, key factors for determining adult sex allocation. For L. dalli, adult sex is regulated by social status: dominants are male; subordinates are female. In social groups of laboratory-reared juveniles, we demonstrate that status also predicts primary sex. Dominant juveniles developed male-typical genitalia, and their gonads contained significantly less ovarian tissue than subordinates, which developed female-typical genitalia. To better understand natural development, we quantified the distribution of juveniles and adults on the reef and analyzed genital papilla and gonad morphology in a sample of wild-caught juveniles. Juveniles were observed in various social environments, and most grouped with other juveniles and/or adults. The majority of field-caught juveniles had female-typical genitalia and bisexual, female-biased gonads. These data are consistent with a single mechanism that regulates sexual phenotype through- out life. Social status could first cause and then maintain through adulthood a female-biased population, allowing individuals to regulate sex based on local conditions, which is important for optimizing lifetime reproductive success.
... L. dalli is a small (18-45 mm adult standard length; SL) marine fish that undergoes socially regulated, bidirectional sex change (Reavis and Grober 1999;Rodgers et al. 2007). This species lives in mixed-sex social groups on rocky reefs in the Pacific Ocean, from Morro Bay, California as far south as the Galapagos Islands, Ecuador (Béarez et al. 2007;Miller and Lea 1972). Under natural conditions, groups range from small (3-10 fish) isolated harems to large aggregations (up to 120 fish/m 2 ) (Steele 1996). ...
Social status can change over a lifetime and affect fitness. Status transitions are often influenced by previous experience such that previous winners tend to dominate in future interactions, while losers tend to remain subordinate. We investigated the role of social status experience on future status contests in the bluebanded goby (Lythrypnus dalli), a highly social, sex-changing fish. Female L. dalli were given long-term experience as alpha (dominant) or beta (subordinate) in a stable social group of three fish (two females, one dominant male). We hypothesized that females with previous dominance experience would be more likely to become dominant in a novel context and change sex, a status-dependent transition. We found that in size-matched pairs, half of the previous alphas and half of the previous betas established and maintained dominance in the novel pair. Previous betas were more likely to become dominant in pairs with small relative differences in physical condition. Betas that initiated more interactions with the male in the stable group were also more likely to become dominant. Experience only had a transient effect on agonistic behavior during status establishment. In pairs in which the previous beta established dominance, individual agonistic efficiency, or the proportion of their approaches that led to a displacement, was lower. There was no long-term effect of experience on the rate of sex change. These data suggest that long-term tenure as a subordinate does not, itself, prevent status ascension and that physical condition and individual behavior are relevant factors that influence L. dalli contests.
... Lythrypnus dalli is a small (standard length (SL) 18-50 mm), marine fish that undergoes socially regulated, bidirectional sex change (Reavis & Grober, 1999;Rodgers et al., 2007). This species lives on rocky reefs in the Pacific Ocean, from Morro Bay, CA, USA to as far south as the Galapagos Islands, Ecuador (Miller & Lea, 1976;Béarez et al., 2007). Reproduction occurs between April and September, during which time the population is femalebiased (Wiley, 1976;Drilling & Grober, 2005). ...
In many social species, there are important connections between social behaviour and reproduction that provide critical insights into the evolution of sociality. In this study, we describe associations between agonistic behaviour and male reproductive success in stable social groups of bluebanded gobies (Lythrypnus dalli). This highly social, sex-changing species forms linear hierarchies of a dominant male and multiple subordinate females. Males reproduce with each female in the harem and care for the eggs. Since aggression tends to be associated with reduced reproduction in social hierarchies, we hypothesized that males in groups with high rates of aggression would fertilise fewer eggs. We also hypothesized that a male’s agonistic behaviour would be associated with his reproductive success. Dominants often exert substantial control over their harem, including control over subordinate reproduction. To address these hypotheses, we quantified egg laying/fertilisation over 13 days and observed agonistic behaviour. We show that there was a significant, negative association between male reproductive success and the total rate agonistic interactions by a group.
While no male behaviours were associated with the quantity of eggs fertilised, female agonistic behaviour
may be central to male reproductive success. We identified a set of models approximating male reproductive success that included three female behaviours: aggression by the highest-ranking female and approaches by the lowest-ranking female were negatively associated with the quantity of eggs fertilised by males in their groups, but the efficiency with which the middle-ranking female displaced others was positively associated with this measure. These data provide a first step in elucidating the behavioural mechanisms that are associated with L. dalli reproductive success.
... dalli). This small [standard length (SL) 18-45 mm] marine goby is highly social and lives on rocky reefs in the Pacific Ocean, from Morro Bay, California to as far south as the Galapagos Islands, Ecuador (Miller and Lea, 1976;Béarez et al., 2007). Mixed-sex social groups of L. dalli vary from small and isolated (3-10 fish) to aggregations of 120 fish/m 2 (Steele, 1996) and are comprised of a dominant, territorial male and multiple subordinate females (St Mary, 1993). ...
Socially regulated sex change in teleost fishes is a striking example of social status information regulating biological function in the service of reproductive success. The establishment of social dominance in sex changing species is translated into a cascade of changes in behavior, physiology, neuroendocrine function, and morphology that transforms a female into a male, or vice versa. The hypothalamic-pituitary-interrenal axis (HPI, homologous to HP-adrenal axis in mammals and birds) has been hypothesized to play a mechanistic role linking status to sex change. The HPA/I axis responds to environmental stressors by integrating relevant external and internal cues and coordinating biological responses including changes in behavior, energetics, physiology, and morphology (i.e., metamorphosis). Through actions of both corticotropin-releasing factor and glucocorticoids, the HPA/I axis has been implicated in processes central to sex change, including the regulation of agonistic behavior, social status, energetic investment, and life history transitions. In this paper, we review the hypothesized roles of the HPA/I axis in the regulation of sex change and how those hypotheses have been tested to date. We include original data on sex change in the bluebanded goby (Lythyrpnus dalli), a highly social fish capable of bidirectional sex change. We then propose a model for HPA/I involvement in sex change and discuss how these ideas might be tested in the future. Understanding the regulation of sex change has the potential to elucidate evolutionarily conserved mechanisms responsible for translating pertinent information about the environment into coordinated biological changes along multiple body axes.
... Distribución: Registrado desde el Golfo de California hasta Ecuador y norte del Perú, incluyendo las islas Malpelo y Galápagos (Allen y Robertson 1994, Chirichigno y Cornejo 2001, Béarez et al., 2007). Se confirma su distribución hasta Punta Sal, Perú, y se incluye las islas Lobos de Afuera. ...
En el presente trabajo se dan a conocer 11 nuevos registros de peces marinos para el Perú. Las colectas fueron efectuadas entre los años 1989 y 2007 en las localidades de Bocapan, Canoas de Punta Sal, Punta Sal (Tumbes); Los Órganos, Isla Foca (Piura); Islas Lobos de Afuera (Lambayeque); Bahía Samanco (Ancash); y Pucusana (Lima). Los nuevos registros para la ictiofauna marina del Perú son: Dasyatis longa, Urobatis halleri, Cephalopholis panamensis, Prognathodes carlhubbsi, Cirrhitus rivulatus, Stegastes beebei, Thalassoma lucasanum, Thalassoma grammaticum, Axoclinus lucillae, Elacatinus punticulatus y Coryphopterus urospilus. Las especies Cirrhitichthys oxycephalus, Lythrypnus dalli y Myripristis leiognathus, fueron anteriormente mencionadas para Perú pero sin existir registros documentados, con la presente publicación se certifica su presencia. Se discute sobre características biogeográficas y ampliación de distribución durante El Niño.
The genus Acyrtus Schultz, 1944 currently includes four species distributed in the western Atlantic (WA), three occurring from the Bahamas to the southern Caribbean, and one endemic to the Fernando de Noronha Archipelago in north‐east Brazil. We describe a new species of Acyrtus based on morphology and genetics from several individuals caught at artificial hard substrates deployed between 10 and 16 m deep at Malpelo Island, Colombian Pacific. The Malpelo clingfish, Acyrtus arturo new species, differs from all its WA congeners by a combination of morphology, meristics and genetics. This species is unique within Acyrtus in having the greatest number of caudal rays (12–13). It can also be distinguished by the greater body height (19.8–27.8% standard length), its longer disc (34.0–39.1% standard length) and the greater distance between anus and disc (13.9–18.1% standard length). A. arturo sp. nov. is the first Acyrtus so far recorded from the eastern Pacific and adds to the already high number of fishes endemic to Colombia's remote oceanic territory of Malpelo.
