Ecología reproductiva del nicuro Pimelodus yuma en la cuenca del río san Jorge, Colombia / Reproductive ecology of nicuro Pimelodus Yuma in the San Jorge river basin, Colombia

Para estudiar la ecología reproductiva del Nicuro Pimelodus yuma (VILLA-NAVARRO ACERO P, 2017) en el río San Jorge, Colombia, se recolectaron 404 individuos, con tallas y pesos que oscilaron entre 14.9-30.6 cm de longitud total (LT) y 27.0-243.0 g de peso total (WT). Las gónadas se conservaron en solución de Gilson, se utilizó la escala de madurez de VAZZOLER para los ovarios y se estimó proporción sexual, índices de madurez sexual, época de desove, talla media de madurez, diámetro de ovocitos y fecundidad. Se encontraron 292 fueron hembras y 112 machos, con talla y peso medios de captura de 21.4 cm LT y 81.5 g, respectivamente. La proporción sexual hembra: macho fue H:M de 2.6:1, con dimorfismo sexual a la talla puesto que las hembras alcanzan mayores longitudes que los machos, talla media de madurez de 20.5 cm LT, ovocitos de 643 µm, fecundidad promedio de 16422 ovocitos y ecuación de fecundidad F =2565 WO 1.062, r =0.95, n =12. Los resultados obtenidos sugieren que el Nicuro es un pez con proporción sexual diferente a lo esperado, desarrollo ovocitario sincrónico en dos grupos, un desove anual con período reproductivo que se extiende de marzo a octubre asociado al ciclo hidrológico del río San Jorge, ovocitos de pequeño tamaño y alta fecundidad asociada al peso de los ovarios.

Reproductive Ecology, Condition, and the Physical Environment of a Temperate Protogynous Hermaphrodite at a Small Scale

<p>Hermaphroditic reef fish display remarkable diversity in mating strategies, social structure, and the timing of sex change. Understanding spatial variation in reproductive ecology and physiological condition is important in the design of marine reserve systems and fisheries management for species that change sex. I investigated patterns in reproductive ecology, condition, and the influence of the underlying physical environment, for a temperate protogynous (female first) hermaphrodite, the spotty (Notolabrus celidotus) at a small spatial scale. First, I used SCUBA surveys to visually estimate density, sex ratio, and size-frequency to describe the social structure of two populations of spotties located at either end of a 9 km gradient in swell exposure. I then collected individuals from both locations to estimate growth, mortality, and the timing of maturation and sex change for each population. To estimate and compare physiological stress and condition of individuals sampled from these two locations, I used otoliths to quantify fluctuating asymmetry (a measure of stress) and I compared this to other commonly used condition indices. Lastly, I estimated spatial variation in social structure and a set of environmental variables at 30 sites along a gradient of swell exposure to investigate correlations between the physical environment and the density, sex ratio, and size-frequency of spotties. The results revealed that social structure differed markedly between two populations but not always as expected. A low ratio of males to females in sheltered Kau Bay suggested that the rate of sex change was constrained for this population (relative to Wahine Park, a more swell-exposed site, where males were more abundant in the population). Individuals from Kau Bay exhibited slower growth and higher mortality estimates, and in line with predictions of the size advantage model, females appeared to change sex at an early age and smaller size relative to Wahine Park. Contrary to expectations, however, low levels of fluctuating asymmetry suggested the population at Kau Bay was less stressed than Wahine Park, despite evidence for reduced physiological condition (Fulton’s condition factor K) and high density at Kau Bay. Differences in fluctuating asymmetry between sexes and size classes suggested that sex-specific fluctuating asymmetry and stressors later in the life history are important in these populations. Furthermore, correlations between social structure and the physical environment were inconclusive and highlight the necessity for large sampling efforts. Overall, this study concludes that availability of spawning-territory may limit the rate of sex change and influence reproductive potential in this species. This process may be applicable to other protogynous species that rely on territory-defense as a mating strategy. Sex-specific expression of fluctuating asymmetry should be considered in hermaphroditic reef fish and the impact of stressors acting on specific stages in the life history of individuals requires further investigation. Furthermore, my results suggest that condition indices and fluctuating asymmetry cannot be used interchangeably to estimate health for these populations (the metrics may provide complementary information). Overall, these results emphasise complex and variable patterns in the reproductive ecology of hermaphroditic species and my work is among the first to demonstrate such patterns over a small spatial scale. Further work can clarify questions raised in this study and benefit the conservation of hermaphroditic reef fish.</p>

Reproductive Ecology, Condition, and the Physical Environment of a Temperate Protogynous Hermaphrodite at a Small Scale

<p>Hermaphroditic reef fish display remarkable diversity in mating strategies, social structure, and the timing of sex change. Understanding spatial variation in reproductive ecology and physiological condition is important in the design of marine reserve systems and fisheries management for species that change sex. I investigated patterns in reproductive ecology, condition, and the influence of the underlying physical environment, for a temperate protogynous (female first) hermaphrodite, the spotty (Notolabrus celidotus) at a small spatial scale. First, I used SCUBA surveys to visually estimate density, sex ratio, and size-frequency to describe the social structure of two populations of spotties located at either end of a 9 km gradient in swell exposure. I then collected individuals from both locations to estimate growth, mortality, and the timing of maturation and sex change for each population. To estimate and compare physiological stress and condition of individuals sampled from these two locations, I used otoliths to quantify fluctuating asymmetry (a measure of stress) and I compared this to other commonly used condition indices. Lastly, I estimated spatial variation in social structure and a set of environmental variables at 30 sites along a gradient of swell exposure to investigate correlations between the physical environment and the density, sex ratio, and size-frequency of spotties. The results revealed that social structure differed markedly between two populations but not always as expected. A low ratio of males to females in sheltered Kau Bay suggested that the rate of sex change was constrained for this population (relative to Wahine Park, a more swell-exposed site, where males were more abundant in the population). Individuals from Kau Bay exhibited slower growth and higher mortality estimates, and in line with predictions of the size advantage model, females appeared to change sex at an early age and smaller size relative to Wahine Park. Contrary to expectations, however, low levels of fluctuating asymmetry suggested the population at Kau Bay was less stressed than Wahine Park, despite evidence for reduced physiological condition (Fulton’s condition factor K) and high density at Kau Bay. Differences in fluctuating asymmetry between sexes and size classes suggested that sex-specific fluctuating asymmetry and stressors later in the life history are important in these populations. Furthermore, correlations between social structure and the physical environment were inconclusive and highlight the necessity for large sampling efforts. Overall, this study concludes that availability of spawning-territory may limit the rate of sex change and influence reproductive potential in this species. This process may be applicable to other protogynous species that rely on territory-defense as a mating strategy. Sex-specific expression of fluctuating asymmetry should be considered in hermaphroditic reef fish and the impact of stressors acting on specific stages in the life history of individuals requires further investigation. Furthermore, my results suggest that condition indices and fluctuating asymmetry cannot be used interchangeably to estimate health for these populations (the metrics may provide complementary information). Overall, these results emphasise complex and variable patterns in the reproductive ecology of hermaphroditic species and my work is among the first to demonstrate such patterns over a small spatial scale. Further work can clarify questions raised in this study and benefit the conservation of hermaphroditic reef fish.</p>

Fitness Implications of the Mating System and Reproductive Ecology of Tuatara

<p>Sexual selection and reproductive strategies affect individual fitness and population genetic diversity. Long-standing paradigms in sexual selection and mating system theory have been overturned with the recent integration of behavioural and genetic techniques. Much of this theory is based on avian systems, where a distinction has now been made between social and genetic partners. Reptiles provide contrast to well-understood avian systems because they are ectothermic, and phylogenetic comparisons are not hindered by complicated patterns of parental care. I investigate the implications of the mating system and reproductive ecology on individual fitness and population genetic diversity of tuatara, the sole extant representative of the archaic reptilian order Sphenodontia. Long-term data on individual size of Stephens Island tuatara revealed a density-dependent decline in body condition driven by an apparently high population growth rate resulting from past habitat modification. Spatial, behavioural, and genetic data from Stephens Island tuatara were analysed to assess territory structure, the mating system, and variation in male fitness. Large male body size was the primary predictor of 1) physical access to females, 2) competitive ability, and 3) mating and paternity success. Seasonal monogamy predominates, with probable long-term polygyny and polyandry. Annually, male reproduction is highly skewed in the wild and in captivity. Over 80% of offspring from a captive population on Little Barrier Island were sired by one male and multiple paternity was found in approximately 18% of these clutches, although it was not detected in any wild clutch. The dominance structure has lead to reduced genetic variation in the recovering Little Barrier Island population. Stephens Island tuatara show fine-scale population genetic structuring that appears to be driven by past habitat modification and a sedentary lifestyle in the absence of sex-biased dispersal or migration. These results will improve conservation management of tuatara by providing guidelines for maximising genetic diversity of small and captive populations and will aid in selecting founders for translocated populations. Because of the archaic phylogenetic position of tuatara, this study provides a baseline for comparisons of mating system evolution in reptiles.</p>

Fitness Implications of the Mating System and Reproductive Ecology of Tuatara

<p>Sexual selection and reproductive strategies affect individual fitness and population genetic diversity. Long-standing paradigms in sexual selection and mating system theory have been overturned with the recent integration of behavioural and genetic techniques. Much of this theory is based on avian systems, where a distinction has now been made between social and genetic partners. Reptiles provide contrast to well-understood avian systems because they are ectothermic, and phylogenetic comparisons are not hindered by complicated patterns of parental care. I investigate the implications of the mating system and reproductive ecology on individual fitness and population genetic diversity of tuatara, the sole extant representative of the archaic reptilian order Sphenodontia. Long-term data on individual size of Stephens Island tuatara revealed a density-dependent decline in body condition driven by an apparently high population growth rate resulting from past habitat modification. Spatial, behavioural, and genetic data from Stephens Island tuatara were analysed to assess territory structure, the mating system, and variation in male fitness. Large male body size was the primary predictor of 1) physical access to females, 2) competitive ability, and 3) mating and paternity success. Seasonal monogamy predominates, with probable long-term polygyny and polyandry. Annually, male reproduction is highly skewed in the wild and in captivity. Over 80% of offspring from a captive population on Little Barrier Island were sired by one male and multiple paternity was found in approximately 18% of these clutches, although it was not detected in any wild clutch. The dominance structure has lead to reduced genetic variation in the recovering Little Barrier Island population. Stephens Island tuatara show fine-scale population genetic structuring that appears to be driven by past habitat modification and a sedentary lifestyle in the absence of sex-biased dispersal or migration. These results will improve conservation management of tuatara by providing guidelines for maximising genetic diversity of small and captive populations and will aid in selecting founders for translocated populations. Because of the archaic phylogenetic position of tuatara, this study provides a baseline for comparisons of mating system evolution in reptiles.</p>

Reproductive Ecology of Forage Alfalfa (Medicago sativa L.): Recent Advances

Plants display an assorted collection of reproductive tactics that eventually play a crucial role in perpetuation of species. Plant reproductive ecology is principally concerned with the adaptive implications of the plant in their vicinity, disparity in qualities allied with pollination, seed dispersal, and seedling establishment. The success in reproduction in most flowering plants depends on ecological interactions with pollinators and seed dispersal agents. Modern tactics in reproductive ecology can integrate proper surveys, advanced pollination studies, interaction between flower and pollinators and clear assessments of population genetic structure, which can provide new opportunities for plant reproductive biology. Alfalfa is an important forage legume and known as “Queen of forages” due to its worldwide adaptability, high yield potential and quality. Alfalfa produces seeds which are primarily used for forage production. It is a gift to livestock industry including dairy, beef, horses, and sheep for grazing, silage, hay etc. Alfalfa is also a medicinal herb with antioxidant, antidiabetic, anti-inflammatory, neuroprotective and cardioprotective properties, utilized for treatment of arthritis, kidney problems. The seeds are exploited in alfalfa sprout industry. The current chapter highlights the reproductive biology of alfalfa from flower development to seed production and its advances.

First reports of Toxophora aurea Macquart (Diptera: Bombyliidae: Toxophorinae) in Argentina, and comments on the biology of two species of the genus

The bee fly Toxophora aurea Macquart is reported for the first time in Argentina. One single specimen of this species was reared from a nest of Isodontia costipennis (Spinola) (Hymenoptera: Sphecidae) in the province of Formosa and others were captured in southern Misiones province, and others housed in entomological collections from the provinces Chaco, Santiago del Estero and Santa Fe. Data about the biology of Toxophora leucon Séguy from individuals reared in nests of Cyphomenes anisitsii (Brèthes), Pachodyneurs guadulpensis (Saussure) and Zethus dicomboda (Spinola) (Hymenoptera: Vespidae: Eumeninae) in the province of Formosa are also reported. These are the first data about the reproductive ecology of these parasitic flies in Argentina.