Primer registro de tres especies de peces en el Río Grande de San Ramón, Costa Rica

Registramos nueve especies de peces durante cuatro giras de muestreo (2016 y 2017) en el Río Grande de San Ramón (cuenca del río Tárcoles, 1 060msnm), tres de ellas por primera vez para esta altitud o cuenca. Previamente, Alfaro cultratus (N=95) solo se informaba hasta 300msnm en la vertiente caribeña y en la cuenca del río Tempisque; Amatitlania siquia (N=4) solo por debajo de 540msnm para la cuenca del río Tárcoles; y Amatitlania septemfasciata (N = 22) desde la vertiente atlántica y por debajo de 600msnm.

Diversidad de la ictiofauna de la laguna Hule, Costa Rica

La laguna Hule es un cráter de origen volcánico que se ha inundado con el tiempo, dando como resultado una gran masa de agua, sin estudios previos sobre su comunidad de peces. Muestreamos durante cinco meses la laguna y una quebrada (Pata de Gallo) con redes, gancho y línea. Los especímenes capturados se identificaron in situ al nivel taxonómico posible más bajo. La laguna tenía especies que normalmente se encuentran cerca de la vegetación acuática: Amatitlania siquia, Amphilophus alfari, Astyanax aeneus, Cynodonichthys sp., Parachromis dovii, Phallichthys amates y Poecilia gillii (dominante: A. aeneus, P. gillii y P. amates). La quebrada estaba dominada por Brachyrhaphis olomina pero también tenía Rhamdia laticauda. Los índices de baja diversidad (1,48 en la laguna y 0,26 en la quebrada) son característicos de los ecosistemas lacustres. Las hembras fueron, como se esperaba, más grandes y abundantes en P. amates y B. olomina; mientras que en P. gilli, algunos machos eran más grandes. El área se ve afectada por la contaminación, la introducción de especies invasoras, la pesca incontrolada y el uso de equipo destructivo de pesca. Proponemos la demarcación del estado de protección del sitio y la organización de un grupo comunitario para proteger a esta comunidad de peces.

The fish that cried wolf: the role of parental care in novel predator recognition in juvenile convict cichlids (Amatitlania siquia)

This study tested if convict cichlids (Amatitlania siquia) with prior predator experience could socially transfer their predator knowledge to their offspring. Prior to reproduction, pairs were assigned to either an experimental or control associative learning treatment, and given novel predator odour from a wolf cichlid (Parachromis dovii) paired with either alarm cue or water respectively. We hypothesized that upon re-exposure to the odour, experimental pairs would socially transfer their acquired predator knowledge to their naïve offspring, which in turn would exhibit antipredator behaviour. While fry from both treatment groups did not show a difference in shoal formation, there is some evidence to suggest a trend in the experimental group regarding parental ability to transfer information to offspring and influence shoal behaviour. When tested individually, experimental fry decreased their activity more than control fry in the presence of the predator odour. This study provides evidence of a unique form of predator learning between parents and offspring, suggesting that biparental care may also serve to provide offspring with information about the habitat into which they are born.

Genetic evidence for mixed broods and extra-pair matings in a socially monogamous biparental cichlid fish

Mobile young under parental care have a high potential for intermixing with other broods, which potentially increases the costs to the foster parents. Here, we examined for the first time the genetic composition of wild-caught broods of the convict cichlid (Amatitlania siquia), a socially monogamous biparental fish, for evidence of brood mixing and adoption. Our microsatellite genotyping data revealed that 79% of broods contained adopted young. Moreover, 25% of broods contained adopted sibsets likely arising from extra-pair matings, a phenomenon hitherto not documented for this species. Overall, adopted foreign fry and host fry in mixed broods were generally different in body length, as would be expected if they have different parents. However, fry from possible extra-pair matings were similar in body length to host fry, suggesting that they are of similar age. Our results are important because they reveal a very high prevalence and degree of brood mixing, and indicate that social monogamy does not necessarily lead to genetic monogamy in the convict cichlid in nature. These findings raise questions about potential brood-mixing mechanisms and the reproductive ecology (especially opportunities for polygamy in nature) of this important model species in the study of animal behaviour.