Selección sexual en machos de Poecilia reticulata (gupis) ante hembras emparentadas

El éxito reproductivo de un individuo es lograr que sus descendientes posean características que les permitan adaptarse mejor al medio. En este sentido, es muy importante reducir en lo posible la endogamia, ya que se ha constatado que reduce la fecundidad de la especie y reduce la supervivencia de la progenie. Para conseguirlo, la selección de la pareja juega un papel fundamental, papel que la mayoría de los trabajos centran en las hembras. No obstante, en este trabajo se demuestra que los machos de gupi (Poecilia reticulata) también tiene capacidad para discriminar entre hembras estrechamente emparentadas o no, seleccionando como pareja aquellas menos familiares. ABSTRACT: The reproductive success of an individual is to achieve that its offprint inherit those features that allow them to a better adaptation to the environment. In this way, it is very important to reduce the endogamy because it reduces the fecundity and the survival rate of the offprint. The sexual selection plays and important role to achieve it, and the majority of works gives this selection capacity to females. However, in this paper it is demonstrated that males of guppy (Poecilia reticulata) are able to recognize siblings and prefer to court not related females.

Preferencias en el apareamiento de las hembras de Poecilia reticulata Peters, 1858, en condiciones de turbidez

[ES] Poecilia reticulata, comúnmente conocida como guppi, presenta un marcado dimorfismo sexual y variada coloración, siendo ésta última un factor importante en la selección sexual. Se estudia las preferencias de las hembras hacia machos con diferencias morfológicas y color en las colas bajo diferentes condiciones de turbidez del agua. No se observó ninguna tendencia en la elección de éstas en función de las características de la cola de los machos, sin embargo, el tiempo de cortejo empleado cambia significativamente en función de la turbidez del agua.

Selección sexual en Poecilia reticulata (Guppys)

[ES] Del análisis de la literatura se puede concluir que las hembras de Poecilia reticulata al seleccionar a sus parejas con fines reproductivos, tienden a escoger machos con una ornamentación llamativa y a individuos que realicen movimientos destacables a la hora de efectuar el cortejo. No obstante, nuestros resultados muestran que la respuesta de selección de las hembras es muy variable, sin que se pueda definir ningún patrón concreto de selección o característica de los machos, tanto de color corporal como de movimientos de cortejo, que se configure como significativamente más atractivo para las hembras.

Estudio de la influencia del fotoperiodo en la natación de los guppies (Poecilia reticulata)

[ES] Se estudia el comportamiento de los guppies expuestos a dos regímenes lumínicos diferentes. Los peces muestran una mayor actividad natatoria durante los periodos iluminados bajo regímenes de fotoperiodo alterado, posiblemente como causa de una respuesta de estrés.

Agresividad agonística en "Poecilia reticulata" Peters, 1859

[ES] Se observa que la asimetría en talla no es determinante en las interacciones agresivas que tienen lugar entre machos de Poecilia reticulata, aunque éstos se muestra más agresivos cuando los contendientes son de talla similar. Por otro lado, el contexto ambiental condiciona la agresividad desplegada, de modo que la posibilidad de contacto directo entre contendientes incrementa la agresividad. Al contrario, cuando el riesgo de predación es muy elevado la agresividad disminuye. La presencia de una hembra en el contexto de interacción no influye en el nivel de agresividad de los machos.

Estudio de la selección sexual de las hembras de "Poecilia reticulata" en diferentes condiciones lumínicas

[ES] Las hembras de Poecilia reticulata tienden a seleccionar a machos de colores llamativos para su reproducción, pero este proceso de selección sexual parece no estar condicionado por la calidad de la luz ambiental. Así, han mostrado una respuesta en la selección muy variable con independencia de si la luz ambiental es blanca o naranja.

Female mating preference for bold males in the guppy, Poecilia reticulata.

Although females prefer to mate with brightly colored males in numerous species, the benefits accruing to such females are virtually unknown. According to one hypothesis of sexual selection theory, if the expression of costly preferred traits in males (such as conspicuous colors) is proportional to the male's overall quality or reveals his quality, a well-developed trait should indicate good condition and/or viability for example. A female choosing such a male would therefore stand to gain direct or indirect fitness benefits, or both. Among potential phenotypic indicators of an individual's quality are the amount and brightness of its carotenoid-based colors and its boldness, as measured by its willingness to risk approaching predators without being killed. Here, we show experimentally that in the Trinidadian guppy (Poecilia reticulata) the visual conspicuousness of the color pattern of males correlates positively with boldness toward, and with escape distance from, a cichlid fish predator. Bold individuals are thus more informed about nearby predators and more likely to survive encounters with them. Mate-choice experiments showed that females prefer colorful males as mates, but prefer bolder males irrespective of their coloration when given the opportunity to observe their behavior toward a potential fish predator. By preferentially mating with colorful males, female guppies are thus choosing on average, relatively bold, and perhaps more viable, individuals. In doing so, and to the extent that viability is heritable, they potentially gain indirect fitness benefits by producing more viable offspring than otherwise.

Interface between culturally based preferences and genetic preferences: female mate choice in Poecilia reticulata.

The relative contribution of genetic and socio-cultural factors in the shaping of behavior is of fundamental importance to biologists and social scientists, yet it has proven to be extremely difficult to study in a controlled, experimental fashion. Here I describe experiments that examined the strength of genetic and cultural (imitative) factors in determining female mate choice in the guppy, Poecilia reticulata. Female guppies from the Paria River in Trinidad have a genetic, heritable preference for the amount of orange body color possessed by males. Female guppies will, however, also copy (imitate) the mate choice of other females in that when two males are matched for orange color, an "observer" female will copy the mate choice of another ("model") female. Three treatments were undertaken in which males differed by an average of 12%, 24%, or 40% of the total orange body color. In all cases, observer females viewed a model female prefer the less colorful male. When males differed by 12% or 24%, observer females preferred the less colorful male and thus copied the mate choice of others, despite a strong heritable preference for orange body color in males. When males differed by 40% orange body color, however, observer females preferred the more colorful male and did not copy the mate choice of the other female. In this system, then, imitation can "override" genetic preferences when the difference between orange body color in males is small or moderate, but genetic factors block out imitation effects when the difference in orange body color in males is large. This experiment provides the first attempt to experimentally examine the relative strength of cultural and genetic preferences for a particular trait and suggests that these two factors moderate one another in shaping social behavior.

The Maintenance and Consequences of a Low Quality Diet in Poecilia Latipinna

The adaptive significance of herbivory in nature is not well understood. In order to document the conditions that select for an herbivorous feeding habit, we must first understand how such a diet is maintained, and the consequences of doing so. A few studies have begun to reveal mechanisms of maintaining herbivory (i.e. selective feeding, diet mixing, etc.) and the associated life history responses (i.e. growth, reproduction, etc.) in terrestrial and marine systems; however, studies of this kind are underrepresented in the freshwater literature. In this study, I use the sailfin molly (Poecilia latipinna) as a model organism to examine diet selectivity and the effects of an herbivorous diet on growth. To study food selectivity, sailfin mollies were fed either disturbed or intact periphyton mats from one of three localities within the Everglades (Water Conservation Area 3B, the Gap, or Chekika). Mats are structured with palatable algal species (i.e. greens and diatoms) comprising the inner components of the mat, and unpalatable species (i.e. cyanobacteria) comprising the outer edges. Fish gut contents were analyzed for each treatment and periphyton locality. Results suggest that when provided access to the inner components of the mats, fish preferentially eat more palatable algae. In a second experiment, effects of an herbivorous diet were examined using neonate sailfin mollies. Fish were fed either commercial food flakes, commercial algae flakes, or ground periphyton, and growth rate was measured weekly, from birth to 21 days. Fish fed the commercial diets grew at a faster rate and reached a larger final size than those fed periphyton. These results suggest that a periphyton diet is limited in nutritional elements compared to a pure algae diet and herbivorous organisms feeding upon it may experience negative effects on growth. By studying the costs and benefits of herbivory in a freshwater system, this paper contributes to a larger study of the question of why herbivory would evolve as an adaptation when seemingly inefficient compared to carnivorous and omnivorous diets.

Role of olfaction and vision cues in feeding behavior and alarm reaction in the catfish pintado, Pseudoplatystoma corruscans

Experiments were performed to investigate senses that are essential for mediating fright reaction and food behavior in Pseudoplatystoma corruscans, pintado. The dilemma ""to feed or to flee"" was also analyzed in fishes with intact and sectioned olfactory tracts, stimulated by alarm substance extracts and food. Fishes were arranged into five groups: fish with intact lateral olfactory tracts (LOT), fish with intact medial olfactory tract (MOT), fish with tracts totally sectioned (TOTAL, both LOT and MOT), sham operated, and nonoperated fish. The five groups were submitted to either alarm substance extract and food stimulus or to distilled water (control) and food stimulus. Fish reacted to food independently of which tract (LOT, MOT or TOTAL) was sectioned; vision seems necessary and elemental to detect and deflagrate food response. Latency of the responses to each reaction was different between groups. None of the fish with sectioned tracts reacted to alarm substance extract, while sham- and nonoperated fish showed the typical alarm behavior response, leading to the conclusion that olfaction is essential for mediating alarm response. These results indicate that others sense systems (e.g., vision) are sufficient to trigger and elicit feeding behavior and that olfaction is not necessary to fully maintain food detection to qualitative and quantitative extent. However, olfactory tract integrity seems to be required for mediation of alarm reaction in P. corruscans.

Parasites of ornamental fish imported into Australia

Five commonly imported freshwater ornamental fish: Poecilia reticulata (guppy); Xiphophorus maculatus (platy); Paracheirodon innesi (neon tetra); Paracheirodon axelrodi (cardinal tetra); and Gyrinocheilus aymonieri (sucking catfish), 361 individuals in total, were examined for parasites immediately after being released from quarantine in Australia. Ten parasites species were found: Camallanus cotti; Centrocestus formosanus; Bothriocephalus acheilognathi; Urocleidoides reticulatus; Tetrahymena corlissi; Chilodonella piscicola; Hexamita sp.; Cryptobia sp.; Chloromyxum sp.; and an unidentified larval nematode. Though shipments had come from up to five different exporting companies, parasite prevalence was uniformly high. We suggest that prior to release, fish transported internationally should be checked for high risk pathogens such as Camallanus cotti, B. acheilognathi and Centrocestus formosanus, and treated for common infections such as Hexamita sp., Cryptobia sp. T. corlissi and Chilodonella piscicola to inhibit the spread of disease and enhance the survival of the fish.

Laboratory evaluation of two native fishes from tropical North Queensland as biological control agents of subterranean Aedes aegypti

The ability of 2 freshwater fishes, eastern rainbow fish Melanotaenia splendida splendida and fly-specked hardyhead Craterocephalus stercusmuscarum stercusmuscarum. native to North Queensland to prey on immature Aedes aegypti was evaluated under laboratory conditions. The predation efficiency of the 2 species was compared to the exotic guppy, Poecilia reticulata, which is commonly used as a biological control agent of mosquito larvae. Of the 3 fish species tested, M. s. splendida was shown to be the most promising agent for the biological control of Ae. aegypti that breed in wells. Melanotaenia s. splendida consumed significantly greater numbers of immature Ae. aegypti than P. reticulata, irrespective of developmental stage or light conditions. Unlike C. s. stercusmuscarum, M, s. splendida could be handled, transported, and kept in captivity for extended periods with negligible mortality. However, M. s. splendida was also an efficient predator of Litoria caerulea tadpoles, a species of native frog found in wells during the dry season. This result may limit the usefulness of M. s. splendida as a biological control agent of well-breeding Ae. aegypti and suggests that predacious copepods, Mesocyclops spp., are more suitable. However, the use of M. s. splendida as a mosquito control agent in containers that are unlikely to support frog populations (e.g., aquaculture tanks and drinking troughs) should be given serious consideration.