Divergent predation environment between two sister species of livebearing fishes (Cyprinodontiformes: Poeciliidae) predicts boldness, activity, and exploration behavior / Ambientes de depredación divergente para dos especies hermanas de peces vivíparos (Cyprinodontiformes: Poeciliidae) predicen el comportamiento de audacia, actividad y exploración

Abstract:Predators can influence a variety of prey traits, including behavior. Traits such as boldness, activity rate, and tendency to explore can all be shaped by predation risk. Our study examines the effects of predation on these behaviors by considering a natural system in which two sister species of livebearing fishes, Brachyrhaphis roseni and B. terrabensis, experience divergent predation environments. In February of 2013, we collected fish in the Río Chiriquí Nuevo drainage, Chiriquí, Panama, and conducted behavioral assays. Using open-field behavioral assays, we evaluated both juveniles and adults, and males and females, to determine if there were differences in behavior between ontogenetic stages or between sexes. We assessed boldness as 'time to emerge' from a shelter into a novel environment, and subsequently measured activity and exploration within that novel environment. We predicted that B. roseni (a species that co-occurs with predators) would be more bold, more active, and more prone to explore, than B. terrabensis (a species that does not co-occur with predators). In total, we tested 17 juveniles, 21 adult males, and 20 adult females of B. roseni, and 19 juveniles, 19 adult males, and 18 adult females of B. terrabensis. We collected all animals from streams in Chiriquí, Panama in February 2013, and tested them following a short acclimation period to laboratory conditions. As predicted, we found that predation environment was associated with several differences in behavior. Both adult and juvenile B. roseni were more active and more prone to explore than B. terrabensis. However, we found no differences in boldness in either adults or juveniles. We also found a significant interaction between 'sex' and 'species' as predictors of boldness and exploration, indicating that predation environment can affect behaviors of males and females differently in each species. Our work demonstrates the importance of considering sex and life history stage when evaluating the evolution of behavior. Rev. Biol. Trop. 65 (1): 267-277. Epub 2017 March 01.

ResumenLos depredadores pueden influenciar una variedad de rasgos de la presa, incluyendo el comportamiento. Los rasgos tales como la audacia, nivel de actividad, y la tendencia a explorar; pueden ser moldeados por el riesgo de depredación. Nuestro estudio examina los efectos de la depredación en el comportamiento al considerar un sistema natural en el que dos especies hermanas de peces vivíparos, Brachyrhaphis roseni y B. terrabensis, se presentan en ambientes de depredación divergente. En febrero 2013, recolectamos peces en el drenaje del Río Chiriquí Nuevo, Chiriquí, Panamá y llevamos a cabo ensayos de comportamiento. Al usar ensayos de comportamiento en campo abierto, se evaluó el comportamiento en juveniles y adultos, machos y hembras, para determinar si los patrones de divergencia diferían entre las etapas ontogenéticas o entre sexos. Se evaluó la audacia como "tiempo en salir" de un refugio a un ambiente nuevo, y posteriormente se midió la actividad y la exploración dentro de ese nuevo ambiente. Nosotros predijimos que B. roseni (una especie que se presenta con los depredadores) sería más audaz, activa y propensa a explorar que B. terrabensis (una especie que no se presenta con los depredadores). En total, probamos 17 jóvenes, 21 machos adultos, y 20 hembras adultas de B. roseni, y 19 jóvenes, 19 machos adultos, y 18 hembras adultas de B. terrabensis. Recogimos todos los animales en Chiriquí, Panamá en Febrero 2013, y los probamos después de un corto período de aclimatación a las condiciones de laboratorio. Como se predijo, se encontró que la depredación ambiental se asoció con varias diferencias en el comportamiento. Tanto adultos y jóvenes de B. roseni eran más activos y más propensos a explorar que B. terrabensis. Sin embargo, no se encontraron diferencias en la audacia en adultos o menores. También se encontró una interacción significativa entre "sexo" y "especie" como predictores de la audacia y la exploración, lo que indica que la depredación puede afectar el comportamiento de los machos y hembras de manera diferente en cada especie. Nuestro estudio demuestra la importancia de considerar el sexo y la etapa del ciclo de vida al evaluar la evolución del comportamiento.

Trophic ecology of the exotic Lerma livebearer Poeciliopsis infans (Cyprinodontiformes: Poeciliidae) in the Lago de Pátzcuaro, Central Mexico / Ecología trófica del pez exótico Guatapote del Lerma Poeciliopsis infans (Cyprinodontiformes: Poeciliidae) en el Lago de Pátzcuaro, Región Central de México

Exotic fish species has caused several impacts on aquatic biodiversity. The Lago de Pátzcuaro has some well-studied exotic species, except the Lerma livebearer Poeciliopsis infans. This fish species was introduced into the Lago de Pátzcuaro before 1997 and the aspects of its biology are still unknown. In this study we assessed aspects of the trophic ecology of this exotic fish, P. infans, using gut content and stable isotope analysis to understand its capacity to tolerate anthropogenic environmental degradation in the Lago de Pátzcuaro. We also determined its trophic guild position (TP) using the TrophLab Program and stable isotope. Niche breadth was calculated by standardized Levins’ Index (Bi). Fish was captured with a seine during wet and dry seasons at six environmentally different sites and gut contents were obtained. We analyzed a total of 239 gut contents of P. infans. The contribution of each food item in the diet was quantified using frequency of occurrence and area percentage. The importance of each prey item was determined according to the index of relative importance (IRI), and the omnivory index (OI) was used to assess the feeding behavior. Fish were categorized by size and the diet was compared between fish sizes and sites. Dorsal muscle tissue and water hyacinth tissue was obtained for nitrogen isotope signature (δ15N) analysis. Additionally, we measured water and habitat quality to evaluate environmental conditions at each site. We concluded that P. infans is an omnivore (OI=0.28) that consumes mainly detritus (44%), epiphytic diatoms (37%), and secondary on terrestrial insects (6%) and zooplankton (10%). The fish can behave as a specialist (Bi=0.39) or generalist (Bi=0.68) and as a primary consumer (TROPH=2.2; TP=2.3) with a feeding strategy that was the same at different sizes, seasons and sites. None of the evaluated sites showed good environmental quality. We argue that P. infans can tolerate changes in water quality and feeding items availability, because it can exploit resources in multiple trophic webs. However, this species could be dependent on habitat complexity, especially in the aquatic vegetation cover.

Las especies de peces exóticas han causado numerosos impactos sobre la biodiversidad acuática. El Lago de Pátzcuaro tiene especies exóticas bien estudiadas, excepto el Guatapote del Lerma, Poeciliopsis infans. Esta especie fue introducida en el Lago de Pátzcuaro antes de 1997 y los aspectos de su biología son aún desconocidos. Se estudiaron aspectos de la ecología trófica de este pez exótico, P. infans, mediante el uso de análisis de contenidos del tracto digestivo para entender su capacidad para tolerar la degradación ambiental antrópica en el Lago de Pátzcuaro. Lo que involucró la determinación del gremio y posición trófica (TP) con el programa TrophLab e isotopos estables. La amplitud de dieta fue calculada con el índice estandarizado de Levin (Bi). Un total de 239 tractos digestivos de P.infans fueron analizados. Los peces fueron capturados con una red tipo chinchorro durante la temporada de lluvias y estiaje en seis sitios ambientalmente distintos. La contribución de cada componente de la dieta fue cuantificada con la frecuencia de ocurrencia y el porcentaje de área. La importancia relativa de cada artículo alimentario fue determinada de acuerdo al índice de importancia relativa (IIR) y el índice de omnivoría (OI) fue usado para estimar la conducta en la forma de alimentarse. La dieta fue comparada entre tallas y entre sitios de estudio. El tejido de músculo dorsal y el tejido de lirio fueron obtenidos para determinar valores de δ15N. De manera adicional, la calidad del agua y del hábitat fue medida para evaluar la condición ambiental en cada sitio. P. infans es un omnívoro (OI=0.28) que consume principalmente detritus (44%), diatomeas epifíticas (37%) y de forma secundaria insectos terrestres (6%) y zooplancton (10%); puede comportarse como especialista (Bi=0.39) o generalista (Bi=0.68) y consumidor primario (TROPH=2.2; TP=2.3). La estrategia alimenticia fue similar entre tallas, temporadas y sitios. Ningún sitio mostró buena calidad ambiental. Los resultados del presente estudio permiten argumentar que P. infans puede tolerar cambios en la calidad del agua y en la disponibilidad de artículos alimenticios, porque puede usar recursos provenientes de múltiples redes tróficas. Sin embargo, esta especie podría ser dependiente de la complejidad del hábitat, especialmente de la cobertura de la vegetación acuática.

Ecology of Phallotorynus pankalos (Cyprinodontiformes: Poeciliidae) in a first-order stream of the upper Paraná Basin

Some aspects of the population ecology of Phallotorynus pankalos in a first-order stream of the Iguatemi River Basin are described based on samples taken from March/2007 to February/2008. A total of 2680 individuals, including 948 males and 1732 females was collected. Adult females are larger than males; theirs mean fecundity was estimated as 6.5 embryos/female. There was a strong correlation between standard length and ovary weight, relative ovary weight, and number of embryos. The size of the first maturation of 50 percent of female population was estimated as 18.24 mm of standard lenght. High female mortality was observed after the first reproduction and sex ratio presents seasonal variation with higher female proportion in the winter.(AU)

Para descrever alguns aspectos da ecologia populacional de Phallotorynus pankalos em um riacho de primeira ordem da bacia do rio Iguatemi foram realizadas amostragens de março/2007 a fevereiro/2008. Um total de 2680 indivíduos, distribuídos em 948 machos e 1732 fêmeas, foi coletado. Fêmeas adultas foram maiores que os machos e sua fecundidade média foi estimada em 6,5 embriões/fêmea. Foi observada forte correlação entre o comprimento padrão e o peso dos ovários, peso relativo dos ovários e número de embriões. O tamanho da primeira maturação de 50 por cento da população de fêmeas foi estimado em 18,24 mm de comprimento padrão. Observamos elevada mortalidade de fêmeas após a primeira reprodução e variação sazonal na proporção sexual, com maior proporção de fêmeas no inverno.(AU)

Distribution of guppies Poecilia reticulata (Peters, 1860) and Phalloceros caudimaculatus (Hensel, 1868) along a polluted stretch of the Paraíba do Sul River, Brazil / Distribuição dos guppies Poecilia reticulata (Peters, 1860) e Phalloceros caudimaculatus (Hensel, 1868) ao longo de um trecho poluído do rio Paraíba do Sul, Brasil

Cyprinodontiformes fishes (guppies) are widely distributed in Neotropical regions and use deteriorated microhabitats in rivers where few species can occur. This study was carried out in a stretch of the Paraíba do Sul River in bracketing a large urban-industrial complex. The aim was to assess eventual effects that the industrial complex could have on distribution of two closely related fish species of guppies, Phalloceros caudimaculatus and Poecilia reticulata. The area was divided into three zones: Z1, 40 km upriver of the major urban-industrial complex of Volta Redonda; Z2, just down river of the complex; and Z3, 30 km down river of the complex. Six sites (two in each zone) were sampled monthly between November 1998 and October 1999, using a standardized fishing effort with cast net throws, trays lifts and seine hauls, covering different microhabitats, that is, riffles, pools and the proximity of the river's margins. Poecilia reticulata was widely distributed, peaking at Z2, the most polluted area, while P. caudimaculatus showed the highest abundance at Z3, being almost absent in Z1. Both species occurred in high numbers throughout the year but they were scarce between April and June. Females outnumbered males for both species in most size classes and at all sites. Juveniles were more abundant than adults, with non-pregnant females outnumbering pregnant ones. Condition factor was always higher in males than females but only males P. reticulata showed significant difference among the three zones, with the highest values at Z2. The higher number of females confirms the expectation that these species can use very polluted areas and that availability of food provided by organic loads allowed their distribution all over the area. Although these two species have shown indication of spatial separation in the study area, their similar seasonal patterns of occurrence suggest that they respond in a similar way to changes in environmental conditions.

Peixes Cyprinodontiformes (guppies) são largamente distribuídos na região Neotropical e usam microhábitats deteriorados em rios onde poucas espécies podem ocorrer. Este estudo foi realizado em um trecho do rio Paraíba do Sul compreendendo um grande complexo urbano-industrial. O objetivo foi avaliar eventuais efeitos que o complexo industrial poderia ter na distribuição de duas espécies de guppies proximamente relacionadas, Phalloceros caudimaculatus e Poecilia reticulata. A área foi dividida em três zonas: Z1, 40 km rio acima do complexo urbano-industrial de Volta Redonda; Z2, imediatamente abaixo do complexo industrial; e Z3, 30 km abaixo do complexo. Seis locais (dois em cada zona) foram amostrados mensalmente entre novembro de 1998 e outubro de 1999, usando um esforço de pesca estandardizado com tarrafas, peneiras e arrastos, cobrindo diferentes microhábitats, isto é, corredeiras, remansos e a proximidade da margem dos rios. Poecilia reticulata foi largamente distribuído, apresentando pico na Z2, área mais poluída, enquanto P. caudimaculatus apresentou a maior abundância na Z3, sendo quase ausente na Z1. Ambas as espécies ocorreram em elevados números ao longo do ano, mas foram escassas entre abril e junho. Fêmeas foram mais numerosas do que machos para ambas as espécies na maioria das classes de tamanho e em todos os locais. Jovens foram mais abundantes que adultos, com fêmeas não grávidas predominando sobre fêmeas grávidas. Fator de condição foi sempre maior nos machos do que nas fêmeas, mas somente machos de P. reticulata apresentaram diferenças significantes entre as três zonas, com os mais elevados valores na Z2. Maior número de fêmeas confirma as expectativas de que estas espécies podem usar áreas bem poluídas e que a disponibilidade de alimento provida pela carga orgânica permite sua distribuição ao longo de toda a área. Embora estas duas espécies tenham apresentado indicações de separação especial, seus similares padrões de ...

Reproduction of the fish Poeciliopsis gracilis (Cyprinodontiformes: Poeciliidae) in Coatetelco, a tropical shallow lake in Mexico

A reproductive analysis of 1 225 specimens of Poeciliopsis gracilis obtained through monthly samples from Coatetelco, a tropical shallow lake in Central Mexico, was made. There was an evident sexual dimorphism, including a difference in body size at the onset of reproduction. Sex ratio deviated significantly from unity. Monthly variations in gonadosomatic (GSI), hepatosomatic (HSI) indexes and ovarian development stages showed that the spawning season was from July to October, coinciding with the rainy season and phytoplankton biomass increase. The largest sizes were 50 mm for females and 43 mm for males. Rev. Biol. Trop. 56 (4): 1801-1812. Epub 2008 December 12.

Se realizó el análisis reproductivo de 1 225 organismos de Poeciliopsis gracilis que se obtuvieron de manera mensual en el lago Coatetelco, un cuerpo somero tropical en México. Se hizo evidente un dimorfismo sexual en las características morfológicas de esta especie. Se observó una diferencia en el tamaño corporal entre los sexos al inicio de la reproducción. La proporción sexual fue diferente de uno. Con base en la variación mensual del índice gonadosomático (IGS), hepatosomático (IHS) y los estadios de madurez gonádica, se observó que la época de reproducción de P. gracilis se realiza entre julio y octubre, que coincide con la época de lluvias e incremento de la biomasa del fitoplancton. La talla más grande registrada fue de 50 mm para las hembras y de 43 mm para los machos.

Indicadores morfológicos y reproductivos del pez Gambusia puncticulata (Poeciliidae) en sitios muy contaminados del río Almendares, Cuba

Reproductive and morphological indicators of the fish Gambusia puncticulata (Poeciliidae) in very polluted sections of Almendares River, Cuba. The Almendares River watershed covers a large portion of Havana city. Human activities have negative impacts over it. We studied the alteration of biological processes in fish from polluted sites. Stressor-based cumulative effects assessment was applied at individual level in Gambusia puncticulata (Poey, 1854). Three sites of Almendares River were sampled monthly from July 2006 to June 2007. Length and weight of females, and condition factor for both sexes, were higher in the impacted sites. An increase of food supply due to eutrophication can explain why fishes are heavier and longer at polluted sites. Gonadosomatic, specific fecundity index and embryo numbers were significantly higher on the reference site. The Hepatosomatic index was higher in females from the most contaminated sites. Differences in δ13C and δ15N among contaminated and reference sites suggest that the food source is not the same. Rev. Biol. Trop. 56 (4): 1991-2004. Epub 2008 December 12.

El río Almendares es el más grande de Ciudad de La Habana. La actividad humana adyacente ejerce un impacto significativo. Evaluamos las alteraciones de los procesos biológicos en los peces que viven en sitios muy contaminados de este río. Se aplicó una metodología basada en los efectos acumulativos de agentes estresantes múltiples a nivel de individuo en la especie Gambusia puncticulata (Poey, 1854). Este estudio se efectuó en tres sitios del río Almendares con muestreos mensuales desde julio del 2006 hasta junio del 2007. Se encontró un incremento en el largo y el peso de las hembras, y en el factor de condición para ambos sexos en los sitios más impactados. Este resultado se atribuye a la mayor disponibilidad de alimento debido a la eutrofización. El índice gonadosomático, el índice de fecundidad específica y el número de embriones por hembra, tuvieron valores significativamente más altos en el sitio de referencia. El largo relativo del gonopodio no mostró diferencia significativa entre sitios. El índice hepatosomático presentó valores más altos en las hembras provenientes de los sitios más contaminados. Las diferencias encontradas para δ13C y δ15N entre los sitios contaminados y el de referencia sugieren que las fuentes de alimento no son las mismas.

Vulnerability of the mosquito larvae to the guppies (Poecilia reticulata) in the presence of alternative preys.

BACKGROUND & OBJECTIVES: The predatory potential of the larvivorous fishes can be affected by the presence of alternative preys. In the present study the predation pattern of the sewage dwelling Poecilia reticulata (Peters 1872) on the larvae of Culex quinquefasciatus Say 1823 (Diptera: Culicidae) was evaluated in the presence of alternative preys. METHODS: The predation of Cx. quinquefasciatus larvae by different size groups of R. reticulata fishes was evaluated. In addition to this, the niche breadth (N) and diet breadth (B) were measured following Manly's selectivity index (Si) as an indicator of variation of such predation pattern in the presence of alternative prey types, like chironomid larvae and tubificid worms. RESULTS: The consumption of IV instar Cx. quinquefasciatus larvae by individual P. reticulata ranged between 65 and 84 in a 3 h feeding period and varied with the size of fish (F2,33 = 34.91; p < 0.001). The selectivity coefficient revealed a significantly low preference for the Cx. quinquefasciatus larvae (0.16, CL: 0.05-0.27; p < 0.05) compared to the chironomid larvae and tubificid worms, when all the three prey types were present. The niche breadth (N) and diet breadth (B) ranged from 0.77 to 0.92 and 0.69 to 0.93, respectively. The total consumption of all the prey types varied with the predator density, but the selectivity index for the mosquito larvae was significantly low in all the instances. INTERPRETATION & CONCLUSION: P. reticulata can consume a good number of mosquito larvae, with the consumption rate varying with the body size. P. reticulata fishes exhibit low preference for mosquito larvae as prey in the presence of alternative controphic preys like chironomid larvae and tubificid worms. Though establishment and sustenance of P. reticulata in new habitats will be favoured by the presence of alternative preys, but vulnerability of mosquito larvae may be reduced with availability of multiple preys in natural conditions.

Alimentación de los peces dulceacuícolas tropicales Heterandria bimaculata y Poecilia sphenops (Cyprinidontiformes: Poeciliidae)

Diet of the tropical freshwater fish Heterandria bimaculata (Haeckel) and Poecilia sphenops Valenciennes (Cyprinidontiformes: Poeciliidae). We analyzed the diet and feeding habits of the fishes Heterandria bimaculata and Poecilia sphenops. Specimens were captured monthly in "Los Carros" damp, Morelos, Mexico (18°37´ N, 98°43´ W). We quantified gut content by the numerical method and by the frequency of occurrence method; and used the MacArthur and Levin´s indices for niche overlap. The diet of H. bimaculata was composed by 16 prey categories, mainly dipterans (Culicidae predominated), independently of sex, size and season. The index of niche overlap was high, from 0.74 to 0.99. The diet of P. sphenops consisted of 11 items, detritus being the most consumed, also independently of sex, size and season. The niche overlap index was high (0.99), indicating overlapping for all analyses. There was little diet overlap (0.26) between the two species. Rev. Biol. Trop. 55 (2): 603-615. Epub 2007 June, 29.

Se analizó la dieta y los hábitos alimentarios de Heterandria bimaculata y Poecilia sphenops. Se tomaron muestras mensuales en la presa "Los Carros", Morelos, México (10°37´ N, 98°43´ W). El contenido intestinal fue analizado de acuerdo con los métodos numérico (No) y el de frecuencia de presencia (FO). Se utilizó el índice de traslape de MacArthur y Levin. H. bimaculata presentó la ingestión de 16 componentes alimenticios. Los odonatos y los himenópteros fueron los más consumidos en le estación de lluvias, mientras que en el estiaje fueron los himenópteros y coleópteros. La talla II fue la que registró la mayor diversidad, siendo los himenópteros los más consumidos en las tres tallas. El índice de traslape en cada uno de los análisis fue de 0.74 a 0.99. P. sphenops consumió 11 tipos de alimento; el detrito registró los porcentajes más altos independientemente de sexo, tamaño y época (índice de traslape = 0.99). Ambas especies comparten seis alimentos, pero en bajas proporciones (índice de traslape = 0.26).

Effects of some trace heavy metals on Poecilia reticulata (Peters).

Three trace heavy metals viz., nickel, copper and zinc were studied for their toxic action against Poecilia retriculata (Peters). Among these, copper was found to be most active followed by zinc and nickel. Accumulations of these metals as well as behavioural studies were carried out after exposing fish to sub-lethal concentration of LC20. It was found that the highest quantity of nickel was accumulated in the fish body followed by zinc and copper. After exposure to sub-lethal concentration of metals some behavioural changes in fish were observed due to stress, such as mucus like secretion over gills, excessive excretion, anoretic condition and increased distance between gills and operculum. In all the cases fin movement was observed. Role and use of such changes as biological indicators or as biological early warning system in water quality assessment has been discussed.

Acción depredadora en el laboratorio de Priapichthys annectens (Regan) (Pisces: Poeciliidae) sobre larvas de Culex spp / Predatory action in the laboratory of Priapichthys annectens (Regan) (Pisces: Poeciliidae) on Culex spp larvae

En condiciones de laboratorio, el pez Priapichthys annectens puede consumir 40-85 larvas de culicino, en 1,3-2,4 minutos. El examen fecal de 37 ejemplares capturados recientemente mostró restos de dípteros, coleópteros, himenópteros, efemerópteros, hemipteros y ácaros. Había restos de artrópodos en 51,4% de los peces, y de larvas de culicinos podría tener utilidad como controlador biológico de larvas de culicinos