ABSTRACT
Introducción: El bivalvo Anadara tuberculosa es un recurso pesquero y económico importante en el Pacífico Este Tropical. La proporción sexual varia a lo largo de su área de distribución, con casos de aparición de hermafroditismo, ocasional para algunas poblaciones, normal en otras. Estas características podrían ser una respuesta a presiones antropogénicas y ambientales. Objetivo: Evaluar la proporción sexual y el hermafroditismo en la especie en el Pacífico de Panamá. Métodos: Se analizó información reproductiva de A. tuberculosa generada entre 1994 y 2020 para el Golfo de Montijo, así como datos de 2017 para el manglar de David. Se aplicaron procedimientos macroscópicos, contrastados con histológicos y se generó un factor de corrección para ajustar la proporción sexual macroscópica, debido al efecto, sobre la proporción sexual, que ocasiona los organismos indeterminados. Resultados: Para el Golfo de Montijo, la histología indicó una proporción sexual hembra a macho de 1:1 hasta 3.2:1, entre 1994 y 2017, mientras que la macroscopía varió de 1.9:1 a 5.1:1 entre 2004 y 2020. Para el manglar de David, la histología indicó una proporción sexual de 3.7:1, y de 7.9:1 por macroscopía en el 2017. En ambas localidades, especímenes más grandes mostraron mayor variación en la proporción sexual, pese a la técnica implementada, así como hermafroditismo protándrico no casual en el 2017. Conclusiones: La aparición del hermafroditismo protándrico y los cambios en la proporción sexual indican que la población de A. tuberculosa, en ambas localidades, está respondiendo a presiones antropogénicas y ambientales.
Introduction: The bivalve Anadara tuberculosa is an important fishery in the Eastern Tropical Pacific. The sex ratio varies along its geographic range and there are cases of hermaphroditism, occasional in some populations, normal in others. These characteristics may be a response to anthropogenic and environmental pressure. Objective: To evaluate sex ratio and hermaphroditism of the species in the Panamanian Pacific. Methods: Data on reproductive features of A. tuberculosa generated between 1994 and 2020 for Gulf of Montijo, as well as 2017 data from mangroves of David was analyzed. Macroscopic diagnosis of individual sex is sensitive to the problem of indeterminate individuals, which in turn can skew the sex ratio analysis; therefore, the macroscopic method was compared with histological sections to generate a correction factor to adjust the macroscopically determined sex ratio. Results: For Montijo, histology indicated that the female to male sex ratio ranged from 1:1 to 3.2:1 between 1994 and 2017, while macroscopy indicated 1.9:1 to 5.1:1 between 2004 and 2020. For David, histology indicated a ratio of 3.7:1, and macroscopy 7.9:1. At both localities, larger specimens had more sex ratio variation, independently of the technique, and there was non-casual protandric hermaphroditism in 2017. Conclusion: The occurrence of protandric hermaphroditism and sex ratio changes suggest anthropogenic and environmental pressure in all populations.
Subject(s)
Animals , Disorders of Sex Development , Bivalvia/growth & development , Panama , WetlandsABSTRACT
Abstract: Clerodendrum indicum (Lamiaceae) is a medicinally important shrub. We have studied the details of its pollination ecology which was hitherto unknown. The work was done during three consecutive years 20122014, based on 118 plants occurring in three widely separated wild populations in West Bengal, India, together with 25 individuals grown in an experimental plot. Details of flower structure and dynamics of floral events, pollen production and pollen dispersal, visitors and pollinators, floral attractants and floral rewards and pollen transfer mechanism have been worked out by standard methodologies with a 10x high resolution hand lens (IRL), a Leica WILD M3B Stereo-binocular microscope (Switzerland) and a Leica DMLB compound bright field light microscope (Germany). The tubular flower of four-day longevity attracts its visitors by visual cues. Flowers are visited regularly by ten species of insects. On the basis of the visitor behaviour, these can be classified into three distinct categories, viz., visitors belonging to Category-I act on cushion and trichome nectaries of calyx and corolla respectively, those of Category-II act on the dehisced anthers and trichome nectaries of corolla while those of Category-III act on dehisced anthers as well as receptive stigma. Majority of the visitors belong to either Category-I or Category-II. They visit only the 2nd day flowers and never visit a 3rd day flower when the stigma assumes receptivity. Therefore, they are not regarded as pollinators but, act as pollen and/or nectar robbers. Those are discriminated by offering secretions from extra-nuptial nectaries of the flower. Visitor species of Category-III, represented by a species of Trigona, constitute the legitimate pollinator of the plant and thereby, making the plant monophilic. Pollen presentation from the bisexual, dichogamous and protandrous flower takes place on the 2nd day, while the stigma assumes its receptivity on the 3rd day of flower opening. Pollen transfer to the body of the pollinator by a 2nd day flower in its male phase is achieved by offering edible pollen grains. On the other hand, a 3rd day flower at its female phase is devoid of the reward (pollen grain). The yellow shiny receptive stigma of such a flower strikingly mimics the freshly dehisced anthers and the pollinators being lured by such a stigma inadvertently transfer pollen onto it. C. indicum is so far the only known species of flowering plants where deceit pollination occurs by anther-mimicking stigma in a bisexual flower. Rev. Biol. Trop. 65 (3): 988-1001. Epub 2017 September 01.
Resumen: Clerodendrum indicum (Lamiaceae) es un arbusto medicinal importante. Hemos estudiado los detalles de la ecología de su polinización hasta ahora desconocida. El trabajo se realizó durante tres años consecutivos 2012-2014, basado en 118 plantas de tres poblaciones silvestres muy separadas en Bengala Occidental, India, junto con 25 individuos cultivados en una parcela experimental. Los detalles de la estructura de las flores y la dinámica de los eventos florales, la producción y la dispersión del polen, los visitantes y los polinizadores, los atractivos florales y las recompensas florales, así como el mecanismo de transferencia de polen han sido estudiados por metodologías estándar con una lente manual de alta resolución 10x (IRL), microscopio estéreo-binocular (M3B, Suiza) y microscopio de campo brillante (Leica DMLB, Alemania). La flor tubular de cuatro días de longevidad atrae a sus visitantes por señales visuales. Las flores son visitadas regularmente por diez especies de insectos. Con base en el comportamiento del visitante, éstos se pueden clasificar en tres categorías distintas, la mayoría pertenecen a la Categoría-I o a la Categoría-II. Visitan solo las flores del segundo día y nunca visitan una flor de 3er día cuando el estigma asume receptividad. Por lo tanto, no se consideran como polinizadores, sino que actúan como ladrones de polen y / o néctar. Estas son discriminadas por ofrecer secreciones de nectarios extra-nupciales de la flor. Las especies de visitantes de la Categoría III, representadas por una especie de Trigona, constituyen el polinizador legítimo de la planta y, por lo tanto, la hacen monofílica. La presentación del polen de la flor bisexual, dicogámica y protándrica ocurre en el 2do día, mientras que el estigma asume su receptividad en el tercer día de la apertura de la flor. La transferencia de polen al cuerpo del polinizador por una flor de segundo día en su fase masculina se logra ofreciendo granos comestibles de polen. Por otro lado, una flor de tercer día en su fase femenina carece de la recompensa (grano de polen). El estigma receptivo brillante amarillo de tal flor simula sorprendentemente las anteras recién abiertas y los polinizadores que son atraídos por tal estigma inadvertidamente transfieren polen en él. C. indicum es hasta ahora la única especie conocida de planta con flor en donde la polinización por engaño se produce por mimetismo de anteras en un estigma de una flor bisexual.
ABSTRACT
In Brazil, the family Gesneriaceae is represented by 23 genera and approximately 200 species. Seemannia sylvatica is an herb that occurs in dense populations in the riverbeds at Serra da Bodoquena. Goals of this study were to report the floral biology (on the first five days of anthesis), as well as to determine the breeding system and the pollinators of S. sylvatica. Data collection was conducted from June 2005 to July 2006 through monthly field trips, lasting for five days. Data on floral biology, breeding system and on the floral visitors were taken from individuals located along a track 2500 m long, in riparian forest of Salobrinha river. Flowers of S. sylvatica are tubular, red, with no perceptive odor and lasted more than five days (ca. 10 - 20 days in individuals transferred to an urban garden and kept in vases). Seemania sylvatica is protandrous, and the male phase occurred between the first and the fourth days of anthesis, while the female one started in the fifth day. Mean nectar volume secreted was 4.77 ± 3.2 µl, with a significative variation among flowers of different ages. Otherwise, nectar concentration average was 9.71 ± 4.41%, and did not varied significantly in flowers of different ages. The flowers of S. sylvatica were pollinated mainly by the hummingbirds Phaethornis pretrei and Thalurania furcata, and pierced by the bee Ceratina chloris. The butterfly Parides anchises orbygnianus was considered an occasional pollinator of these flowers. Seemannia sylvatica is self-compatible, since fruit set occurred on the experiments of spontaneous self-pollination, manual self-pollination, cross-pollination and open pollination (control). The protandry, coupled with the pattern of nectar production, characterized by low volume and solute concentration, which induces the pollinators to visit different flowers in a given circuit foraging, act maximizing the likelihood of cross-pollination in S. sylvatica. Moreover, the high proportion of fruit set by autogamy is an important strategy considering that S. sylvatica is visited by few species, being pollinated mainly by P. pretrei. Therefore, in the absence of these visitors, the formation of fruits may be achieved.
No Brasil, a família Gesneriaceae é representada por 23 gêneros e cerca de 200 espécies. Seemannia sylvatica é uma espécie herbácea que ocorre em densas populações nos leitos de rios da região da Serra da Bodoquena. Os objetivos deste estudo foram conhecer a biologia floral (nos primeiros cinco dias de antese), determinar o sistema reprodutivo e os polinizadores de S. sylvatica. A coleta de dados foi realizada no período de junho de 2005 a julho de 2006 através de viagens mensais a campo, com duração de cinco dias. Dados sobre a biologia floral, o sistema reprodutivo e sobre os visitantes florais foram tomados em indivíduos localizados ao longo de uma trilha de 2500 m de extensão, em área de mata ciliar do rio Salobrinha. As flores de S. sylvatica são tubulosas, vermelhas, inodoras e duram mais de cinco dias (ca. 10 - 20 dias em indivíduos transferidos para jardim e mantidos em vasos). Seemannia sylvatica apresenta protandria, sendo que a fase masculina ocorreu entre o primeiro e o quarto dia de antese e a feminina a partir do quinto dia. O volume médio de néctar secretado foi de 4,77 ± 3,2 µl, tendo variado significativamente em flores de diferentes idades. Por outro lado, a concentração média do néctar foi de 9,71 ± 4,41%, e não houve diferença significativa nas diferentes idades da flor. As flores de S. sylvatica foram polinizadas principalmente pelos beija-flores Phaethornis pretrei e pelas fêmeas de Thalurania furcata, e pilhadas pela abelha Ceratina chloris. A borboleta Parides anchises orbygnianus foi considerada polinizadora ocasional dessas flores. Seemannia sylvatica é autocompatível, havendo formação de frutos nos experimentos de autopolinização espontânea, autopolinização manual, polinização cruzada e controle. A protandria, aliada ao padrão de produção de néctar em S. sylvatica, caracterizado pelo baixo volume e concentração de solutos, que induz os polinizadores a visitarem flores diferentes num dado circuito de forrageamento, agem maximizando a probabilidade de ocorrência da polinização cruzada. Por outro lado, a alta proporção de frutos formados por autogamia é uma estratégia importante tendo em vista que S. sylvatica é visitada por poucas espécies, sendo polinizada principalmente por P. pretrei. Portanto, na ausência desses visitantes, a formação de frutos pode ser assegurada.
