Poecilia Velifera Research Articles

Intra- and interspecific behavioural ecology within and between Mollienesia males (sailfin molly Poecilia velifera and shortfin molly P. mexicana) in mangroves of the Yucatán peninsula

Abstract Throughout their distribution range, sailfin and shortfin mollies of the genus Poecilia inhabit overlapping habitats; however, little is known about its behavioural coexistence. We first describe the ethogram of Poecilia velifera and P. mexicana in a mangrove of Yucatan. Furthermore, we identify behavioural strategies of each size morphotype/species. We describe reproductive, territorial, and cleaning behaviours in two sympatric species of mollies in their natural context, with emphasis of their behavioural interactions and coexistence. Specifically, here we document (i) specific reproductive strategies in male P. velifera morphotypes (large, intermediate-ornamented and ‘cryptic-intermediate’), suggesting that cryptic-intermediate males have advantages that suggest consequences for their reproductive success; (ii) frequent courtship and sexual behaviours from P. mexicana males directed to P. velifera females, that deserve future attention to determine the possible generation of hybrids; and (iii) increased aggressive behaviour and territoriality of P. mexicana relative to those observed in P. velifera.

Effects of salinity on gill histology in sailfin velifera (Poecilia velifera)

Effects of salinity on gill histology in sailfin velifera (Poecilia velifera)

Tolerance to salinity and its effect on development of velifera molly Poecilia velifera (Regan 1914)

ABSTRACT Velifera molly (Poecilia velifera) has an ecophysiological interest related to euryhalinity. To evaluate its tolerance and performance in different salinities, and the ability to be reared at diverse locations, Median Lethal Salinity (LS50) and growth performance were investigated. In experiment 1, 120 juveniles were tested through direct transfer to salinities 0, 24, 48, 60, 72, and 78 psu for 96 h. In experiment 2, 160 juveniles were gradually acclimatized to salinities 0, 12, 24, and 36 psu. The experiment was conducted using recirculation aquaculture systems (RAS) for 75 d. LS50-96 h was estimated at 71.1 psu and safe salinity at 7.1 psu. The final weight, weight gain, and feed intake had an inverse relationship to salinity, reflecting the sublethal effects. The apparent feed conversion rate was directly related to salinity, presented a better performance in freshwater conditions. There was no mortality in experiment 2, allowing the species to be maintained for long periods in the analyzed salinities.

Feeding ecology of the waterbirds in a tropical mangrove in the southeast Gulf of Mexico

ABSTRACTSpecies that exploit the same type of environmental resources are defined as a guild, which have similar needs in the use of food or habitat. It was analyzed the diet of five waterbirds’ offsprings species (Neotropic Cormorant (Nannopterum brasilianus), Reddish Egret (Egretta rufescens), Boat-billed Heron (Cochlearius cochlearius), Snowy Egret (Egretta thula) and Great Egret (Ardea alba)), by prey identification and calculated the relative importance, overlap and breadth diet. The general diet of the piscivorous guild consisted of 17 fish species from 13 genera and eight families. The highest overlap was between the Reddish Egret and Boat-billed Heron. Fish species dominated the diets of all studied waterbirds, Poecilia velifera was the most abundant prey species in each of the birds, suggesting that they are abundant in the wetlands system of northern Yucatan. Diet overlap in waterbirds species depends on the use of resources and feeding habitat. Since reproductive success largely depends on the availability of food resources, mainly of resident or estuarine fishes. The information about diet is important for the conservation of waterbirds.

Effects of salinity on sexual maturity and reproduction of Poecilia velifera

Poecilia velifera is a popular fish in freshwater aquarism that naturally inhabits aquatic habitats with a wide range of salinities. Nonetheless, the effects of different salinities on the reproductive success and sex ratio of the species remain unknown. Male sex characters, sex ratio and reproductive success of P. velifera were evaluated by maintaining 160 juveniles (0.078 ± 0.011 g) in four different salinities (0; 12; 24; 36 g/L), with four replicates. The only modification observed in males was the formation of a copulatory organ from the anal fin, which was used to distinguish them from females. Timing of the formation of the male copulatory organ, and the weight and total length of males when it occurred, were recorded. Twenty-eight fish from each treatment were euthanized after 150 day to examine the gonads and confirm sex. Eight females and four males from each treatment were then kept in their respective salinity treatments for 65 days to examine the effects of salinity on reproduction. Males were kept with females in the different treatments for 15 days, at which point they were removed. Salinity was negatively correlated with male weight and length. Salinity also affected the sex ratio, with the percentages of males and females being 32.5 and 67.5%, and 27.5 and 72.5% in the salinities of 24 and 36 g of salt/L, respectively. Fifty percent of the females kept in freshwater reproduced, while there was no reproduction in the other treatments. The maintenance of P. velifera in freshwater promoted greater reproductive success and precocity, as well as larger males.

Parasites of fish Poecilia velifera and their potential as bioindicators of wetland restoration progress

Fish harbor a high diversity of parasites that play an important role for the ecosystem. Because these parasites have different life-cycle traits, changes in their populations or communities may provide useful information related to ecosystem health. Highly stressful conditions may reduce parasite communities or populations. However, it is not a rule since host-parasite interactions are hardly predictable. In this study, macroparasites of the fish sailfin molly (Poecilia velifera) from three sites (conserved, degraded and under restoration) located within a mangrove wetland area, in the Terminos Lagoon (southern Gulf of Mexico), were analyzed in order to determine their potential use as bioindicators. A total of 198 fish were examined for parasites. Six parasite species were found: two crustaceans (Argulus sp. and Ergasilus aff. cerastes), one trematode (Centrocestus formosanus), one monogenean (Gyrodactylus sp.) and two nematodes (Contracaecum sp. and Cuculanus sp.). There were no significant differences in the structure of parasite infracommunities as well as in prevalence and intensity of parasite populations between degraded and conserved sites. However, the site under restoration had poorer infracommunities and smaller populations of crustaceans and trematodes, which suggests that restoration efforts have not improved the ecological conditions. Based on these results, it is conjectured that parasites of P. velifera did not show useful information to provide a diagnosis related to ecosystem health. Beyond this ecological subject, the present study represents new host record for most parasite species found.

Colorful invasion in permissive Neotropical ecosystems: establishment of ornamental non-native poeciliids of the genera Poecilia/Xiphophorus (Cyprinodontiformes: Poeciliidae) and management alternatives

ABSTRACT Headwater creeks are environments susceptible to invasion by non-native fishes. We evaluated the reproduction of 22 populations of the non-native livebearers guppy Poecilia reticulata, black molly Poecilia sphenops, Yucatan molly Poecilia velifera, green swordtail Xiphophorus hellerii, southern platyfish Xiphophorus maculatus, and variable platyfish Xiphophorus variatus during an annual cycle in five headwater creeks located in the largest South American ornamental aquaculture center, Paraíba do Sul River basin, southeastern Brazil. With few exceptions, females of most species were found reproducing (stages 2, 3, 4) all year round in the creeks and gravid females of all species showed small sizes indicating stunting. Juveniles were frequent in all sites. The fecundity of the six poeciliids was always low in all periods. The sex ratio was biased for females in most species, both bimonthly as for the whole period. Water temperature, water level and rainfall were not significantly correlated with reproduction in any species. Therefore, most populations appeared well established. The pertinence of different management actions, such as devices to prevent fish escape, eradication with rotenone and research about negative effects on native species, is discussed in the light of current aquaculture practices in the region.

Los peces como indicador de restauración de áreas de manglar en la costa norte de Yucatán

Mangroves are well recognized for the ecological services that they provide to many fish species. Previous studies on ecological restoration have overlooked these ecological functions, as they are generally focused on the restoration of vegetation cover. The objective of this study is to determine the function of mangroves as nursery and feeding grounds for fishes, by assessing the species composition and abundance in sites with different restoration time. Two samplings were performed in 4 sites where mangrove is recovering along the Yucatán coast —Celestún 1, Celestún 2, Yucalpetén, Progreso—. A total of 22 fish species were recorded, the higher richness and diversity were recorded in Celestún 2 (Gambusia yucatana, Poecilia velifera, Mugil cephalus and Anchoa mitchilli were the most abundant). In Progreso, the diversity was lower due to the dominance of G. yucatana (>90%). The site with the longest restoration time presented juveniles of detritophagous and zoobentophagous species, which show the nursery and feeding functions of the area. These marine species are involved in the transfer of energy and nutrients to adjacent systems, also a great dominance of G. yucatana was found, which is an endemic and characteristic fish species from the mangrove ecosystem in Yucatán.

Ictiofauna de sistemas cárstico-palustres con impacto antrópico: los petenes de Campeche, México

"Petenes” are small springs and associated streams that drain into wetlands near the coast in karstic areas. We studied composition, distribution, and abundance of the ichthyofauna in Los Petenes region (northwest Campeche). Two petenes displaying different degrees and types of anthropic impact were selected, Hampolol and El Remate. Hampolol has a smaller area but a longer derived stream; it is located within a protected area, but has been invaded by tilapia. El Remate is a popular spa, with no tilapia; it has a larger area but a shorter derived stream. At each “petén”, several sites in the main spring, the associated stream, and secondary (temporary) springs were sampled in the rainy and dry seasons. Fishing gear was variable (throw net, gill net, small and large seine nets), but effort was uniform. We recorded temperature, dissolved oxygen, salinity, and depth at each site and season; also, we noted the different types and intensities of anthropic impact (channelization, presence of exotic species, recreational use, etc.) at each petén. We compared the petenes in terms of their environmental quality and fish fauna (composition, distribution, abundance, biomass); we also tested for effects of season and site within each petén. The study found 27 species of fishes, included in 18 genera and eight families, 24 species in Hampolol and 20 in El Remate. The geographical range of ‘Cichlasoma’ salvini, Rivulus tenuis, Phallichthys fairweatheri, Xiphophorus hellerii, and X. maculatus is extended. The dominant species in both seasons was Astyanax (probable hybrids A. aeneus × altior at Hampolol, pure A. altior at El Remate), which contributed most of the abundance and biomass, together with Vieja synspila and Poecilia velifera. A significantly greater overall diversity (H’n=3.31) was recorded in Hampolol compared to El Remate (H’n=2.10). Cluster analysis of sites by species presence allowed distinction of two groupings within each petén: permanent waters (i.e., main spring, stream) vs. temporary sites (secondary springs, which dry out in winter). Environmental parameters (except salinity) presented significant differences by site and season; a canonical correspondence analysis indicated that the distribution of fish assemblages was influenced by the environmental parameters in both seasons. In terms of composition, historical factors play a role in the differences between the fish assemblages of the two petenes, especially concerning the presence of Astyanax hybrids and Xiphophorus spp. in the southern petén (Hampolol) and Poecilia velifera in the northern petén (El Remate)

Euclinostomum heterostomum infection in guppies Poecilia reticulata cultured in southern Thailand

During April to June 2009 and February 2010 to February 2011, numerous digenetic trematode metacercariae were observed embedded in the muscles of guppies Poecilia reticulata cultured at Kidchakan Supamattaya Aquatic Animal Health Research Center, Songkhla, southern Thailand. A total of 424 guppies were examined to identify the parasite and to study its pathogenicity. Based on conventional parasitological techniques, the parasitic digenean found in the guppies was identified as Euclinostomum heterostomum Rudolphi, 1809. Histological analysis revealed numerous metacercariae embedded in the fish muscle. A life cycle study indicated that the snail Indoplanorbis exustus was the first intermediate host, with the guppies serving as the second intermediate host. No E. heterostomum metacercariae were found in cohabited fish species, giant sailfin molly Poecilia velifera or platy Xiphophorus maculatus, which indicated that the guppy was the only suitable fish host present.

The occurrence and reproductive status of Yucatan molly Poecilia velifera (Regan, 1914) (Poeciliidae; Cyprinodontiformes): an alien fish invading the Songkhla Lake Basin, Thailand

A non-native fish, the Yucatan molly Poecilia velifera (Regan, 1914), has recently become established in the Songkhla Lake Basin, south Thailand. Based on our field surveys in December 2007, we conclude that this species is present only in the Haadkaew Lagoon and the southernmost part of the Songkhla Lagoon, the Thale Sap Songkhla. We sampled P. velifera monthly for 13 months (January 2007-January 2008), using beach seine and cast net, to obtain information on its population structure, morphology and reproduction. It was found that male and female P. velifera became sexually mature at 16.8 and 17.1 mm standard length, respectively. The overall sex ratio of males to females was 1.0:1.8. However, the proportion of males was less within specimens belonging to larger size classes. P. velifera reproduced continuously throughout the year but with two peaks, one in March-May and another in August-December.

English

  Seven growth periods were completed on juvenile velifera (Poecilia velifera) for a period of 2 weeks to determine the optimal water type for best daily growth, food intake, feed conversion ratio, weight gain, survival and condition factor.  Four water types (T1 = 25°C W1, T2 = 30°C W1, T3 = 25°C W2, T4 = 30°C W2) were used to grow up P. velifera for 105 days. In each aquarium, fifteen individuals were stocked and fed to satiation twice a day.  Bulk weight of each group was measured 2 weeks interval.  Growth rate did not increase with water temperature. Water quality made difference.  Fish with W1 grew better than with W2. Fish in T1 had the best growth (daily growth 10.37 mg/day).  Food intake was the highest in T1. Feed conversion ratio did not differ significantly among groups.  Survival was low among 4 groups (T1, T2, T3, and T4 were 55.6, 53.3, 53.3, and 33.3%, respectively), but not significant. Condition factor was the best in T1 (1.61).   Key words: Water type, Poecilia velifera, growth, temperature, survival.

Patterns of Inheritance of Mating Signals in Sailfin and Shortfin Mollies (Poeciliidae: Poecilia: Mollienesia)

AbstractDivergence in mating signals is a primary factor leading to reproductive isolation, and thus, speciation. However, the genetic changes underlying such divergence are poorly understood, especially in vertebrates. We used two species of poeciliid fishes, Poecilia velifera and P. mexicana, to explore the link between genes and mating behaviors that has resulted in pre‐mating reproductive isolation between these species. Using backcross hybrids created from the F1 male offspring of reciprocal interspecific crosses between a sailfin molly (P. velifera) and a shortfin molly (P. mexicana), we examined the effects of Y‐linkage and autosomal contributions on the expression of two male mating behaviors: courtship displays and gonopodial thrusts. The F1 hybrid males displayed a strong influence of sire on courtship display rates, with F1 males sired by the sailfin species showing courtship display rates that were up to three times higher than the rates of displays performed by F1 males sired by the shortfin species. These results suggest a Y‐linked genetic effect on the expression of courtship display behavior. Comparisons between backcross hybrid males with sailfin Y‐chromosomes or shortfin Y‐chromosomes suggested that the interaction of autosomal genes also influences the inheritance of courtship display rates. Sailfin autosomal genes significantly increased the probability of performing courtship displays for hybrid males, and increased display rate for males from the sailfin Y‐chromosome line. Autosomal genes had less of an impact on gonopodial thrusting behavior, however, thrust rates did significantly decrease with an increasing proportion of sailfin autosomes in males from the shortfin Y‐chromosome line. These results suggest that the inheritance of species differences in mating signals between shortfin and sailfin mollies involves both genes found on the Y‐chromosome and autosomal gene influences on their expression.

Geographical variation of genetic and phenotypic traits in the Mexican sailfin mollies, Poecilia velifera and P. petenensis

Comparing the patterns of population divergence using both neutral genetic and phenotypic traits provides an opportunity to examine the relative importance of evolutionary mechanisms in shaping population differences. We used microsatellite markers to examine population genetic structure in the Mexican sailfin mollies Poecilia velifera and P. petenensis. We compared patterns of genetic structure and divergence to that in two types of phenotypic traits: morphological characters and mating behaviours. Populations within each species were genetically distinct, and conformed to a model of isolation by distance, with populations within different geographical regions being more genetically similar to one another than were populations from different regions. Bayesian clustering and barrier analyses provided additional support for population separation, especially between geographical regions. In contrast, none of the phenotypic traits showed any type of geographical pattern, and population divergence in these traits was uncorrelated with that found in neutral markers. There was also a weaker pattern of regional differences among geographical regions compared to neutral genetic divergence. These results suggest that while divergence in neutral traits is likely a product of population history and genetic drift, phenotypic divergence is governed by different mechanisms, such as natural and sexual selection, and arises at spatial scales independent from those of neutral markers.

Female mating preferences for male morphological traits used in species and mate recognition in the Mexican sailfin mollies, Poecilia velifera and Poecilia petenensis

We tested whether sexually selected morphological traits in the sailfin mollies, Poecilia velifera and Poecilia petenensis, are also used in species recognition. Our first experiment, using live males as stimuli and providing females with olfactory as well as visual cues, found that females of both sailfin species preferred conspecific males to males of shortfin species. However, neither species preferred conspecific males when compared with heterospecific sailfin males, suggesting that premating reproductive isolation is not well developed between them. Our second experiment, providing females with only visual cues when distinguishing between live males, found that females of P. velifera preferred the larger of 2 stimulus males, regardless of whether the larger male was a conspecific or an heterospecific sailfin male. Such a preference for the larger sized male was not found in P. petenensis .T o further investigate the role of the dorsal ‘‘sailfin’’ in species recognition, we used model males that varied only in the species identity of their dorsal fins. Females of both sailfin species preferred conspecific models with conspecific sailfins to those with dorsal fins of the shortfin species. In addition, females of P. velifera preferred the model with the largest sailfin, regardless of species identity. Similarly to the live male experiments, females of P. petenensis did not distinguish between conspecific and heterospecific sailfins. Overall, our study suggests that females of P. velifera have a generalized preference for larger males and that species-specific differences in sailfin shape do not lead to premating reproductive isolation between these 2 sailfin species.

Within and Between Species Variation in Male Mating Behaviors in the Mexican Sailfin Mollies Poecilia velifera and P. petenensis

AbstractPolymorphism in male morphology is often correlated with the expression of alternate behavioral tactics. This relationship between behavioral and morphological polymorphisms, however, is less well understood. We characterized male mating behaviors and morphological variation within and between Poecilia velifera and P. petenensis to understand mating signal evolution in the sailfin molly lineage. In addition, we examined whether differences between these species in the size range of mature males and the strength of allometry between dorsal fin size and body length could explain the variation observed in their expression of different mating behaviors. We determined each male's mating behavior profile by observing the behavior of a single male in the presence of a receptive female. We found that P. velifera showed evidence of an alternate male mating strategy, with small males generally performing only gonopodial thrusts (forced insemination attempts) towards receptive females, while large males performed courtship displays as well as gonopodial thrusts. Males of P. petenensis performed similar rates of courtship displays and gonopodial thrusts regardless of body length. Little variation existed among populations of P. velifera in mating behaviors, while males from different populations of P. petenensis showed population‐specific average rates of each mating behavior. Population differences in P. petenensis may be driven, in part, by its occurrence in more variable habitats than those occupied by P. velifera. Variation among individuals in the mating repertoire of P. velifera, but not P. petenensis, suggests that the greater range of variation in male size at maturity, as well as considerably stronger allometry between dorsal fin size and body length, may explain why males of P. velifera show the greatest degree of expression of alternate male mating behaviors when compared to other sailfin species. These results also suggest an important role of morphological polymorphisms in predicting the expression of alternate male mating behaviors.

Morphological divergence within and between the Mexican sailfin mollies,Poecilia veliferaandPoecilia petenensis

This study examined the patterns of morphological variation both between species, and between sexes and among populations within each species of the Mexican sailfin mollies,Poecilia veliferaandPoecilia petenensis, using geometric morphometrics and linear measurements of morphological traits. While sexes within each species differed in characteristics that may be important in sexual selection, such as length of the dorsal fin, species differed in traits, such as body depth, that may also be influenced by natural selection due to differences in habitats. Within each species, many morphological traits were similar among populations, but important differences, including caudal peduncle depth inP. petenensis(but not inP. velifera), suggested that habitat differences may also be important in shaping population divergence independently within each species. Indeed, the evolutionary vectors of male morphological population divergence for each species differed by an angle of 98·5°, representing nearly orthogonal vectors and suggesting independent shape divergence between these two molly species. Finally, geographic isolation did not explain the morphological differentiation seen among populations, suggesting that natural and sexual selection were strong forces promoting morphological diversification within these two species, despite the potential for a high degree of population connectivity and gene flow.

Presence of an Intrapineal Circadian Oscillator in the Teleostean Family Poeciliidae

In most fish, rhythmic melatonin production is controlled by circadian oscillators located within the pineal (=pineal clocks) that are reset daily by the ambient light:dark (LD) cycle. However, one question that has yet to be addressed concerns the phylogenetic distribution of the pineal clock within fish families. We tested whether a pineal clock identified in the sailfin molly (Poecilia velifera) in an earlier study is also present in some other representatives of the teleostean family Poeciliidae. Isolated pineals from adults belonging to the genusPoecilia(P. veliferaalbino,P. reticulata,andP. sphenops), genusXiphophorus(X. helleriandX. maculatus), and genusLimia(L. vittata) were obtained and cultured under LD and/or continuous darkness (DD) at constant temperature (27°C). With one exception, free-running rhythms in melatonin release with circadian periodicities ranging from 19.5 to 27.4 h (n=26) were detected in isolated pineals from all poeciliid representatives tested under DD exposure. In addition, rhythmic melatonin production was also observed in isolated pineals of some representatives tested from all three genera under LD exposure, suggesting the property of direct photosensitivity. Taken together, these data suggest that a circadian oscillator residing in the pineal of the sailfin molly also appears to be present in all of the poeciliid representatives tested in our system, supporting the notion that the presence of a pineal clock occurs at the family level of taxonomic organization.

Properties of the Melatonin-Generating System of the Sailfin Molly,Poecilia velifera

The properties of the melatonin-generating system of a tropical teleost, the sailfin molly (Poecilia velifera), were investigatedin vitroin a series of experiments using static or perifusion culture techniques. The properties examined included photic entrainment, circadian rhythmicity under continuous light (LL) and continuous darkness (DD), functionality of the melatonin-generating system at birth, and presence of multiple circadian oscillators in the molly pineal. Pineal glands or skull caps with the pineal gland firmly attached were dissected from adult and new-born fishes, respectively, and placed into static or perifusion culture at constant temperature (27°C) depending upon the experiment. Melatonin release in samples was quantified by RIA. Rhythmic melatonin release was observed from isolated adult pineals under 12L:12D and 14L:10D, with low amounts of melatonin released during the light and high amounts during the dark. Melatonin release was inhibited by LL. However, under DD, melatonin release was robust and rhythmic with a circadian period (Tau) that ranged between 21.3 and 27.0 h (n=21). Pineals from new-born (1-day old) mollies released melatonin rhythmically under a light:dark cycle and DD in both static and perifusion culture. Melatonin release from half and quarter pineals of adult mollies under DD was robust and rhythmic with circadian periods that ranged between 22.5 and 29.0 h (n=19). Taken together, these data show that the molly pineal is photosensitive, fully functional from birth, and contains multiple circadian oscillators (at least four) regulating melatonin production.

Sexual and Aggressive Behaviour in Species Hybrids of Poecilia mexicana and Poecilia velifera (Pisces, Poeciliidae)

AbstractThe inheritance of sexual behaviour patterns was studied in species hybrids of Poecilia mexicana and Poecilia velifera. In addition, the aggressive behaviour and some morphological characters have been investigated and checked for a possible correlation between and within these three different traits studied. All the characters are inherited polygenically. The minimum genetic factors could be estimated only for some characters.