ABSTRACT
ABSTRACT Neotropical Piper species have bisexual flowers. Such reproductive trait is considered basal in this pantropical genus. However, neotropical species having unisexual (staminate) flowers along with bisexual ones have also been reported. Dichogamy is common in the genus, associated with either self-compatibility or -incompatibility, as well as with entomophily. We analyzed a natural population of Piper caldense in a Atlantic Forest area (Viçosa municipality, Minas Gerais state, southeastern Brazil). Preliminary observations indicated that the species produces two flower types. We analyzed flower sex in spikes of 50 plants. We obtained additional information through morphological and anatomical studies and scanning electron microscopy analyses. The longevity and exposure dynamics of stigmatic papillae and the pollen release sequence of all four stamens were investigated to verify the degree of dichogamy. Pollination tests were performed, pollinators were identified and their visitation frequency was recorded. Piper caldense has both bisexual and staminate flowers, each flower type being located on separate spikes. These spikes occurred on the same plant, thus indicating andromonoecy; furthermore, plants having only spikes with staminate flowers were also observed. This gender had not yet been reported to the genus. Gradual and sequential exposure of stigmatic papillae associated with asynchronous pollen release (one stamen a day) resulted in incomplete protogyny. Hand pollination tests showed that the species is self-incompatible. Social bees, mainly Apis mellifera and Melipona spp., were the major pollinator group. Our study reinforces the need to associate morphological analysis with floral biology and indicates future changes in studies addressing reproductive traits associated with the phylogeny of the Piper genus.
RESUMEN Las especies neotropicales de Piper presentan flores bisexuales, condición considerada basal al interior de este género pantropical. Sin embargo, fueron observadas especies neotropicales con flores unisexuales (estaminadas), además de las bisexuales. La dicogamia es común en el género y se encuentra asociada a la autocompatibilidad o incompatibilidad, al igual que la entomofilia. Fue analizada una población natural de Piper caldense en un área de bosque Atlántico (municipio de Viçosa, Minas Gerais, sureste de Brasil). Las observaciones preliminares indicaron que esta especie produce dos tipos florales, para lo cual fue analizada la sexualidad de las flores en 50 espigas a través de estudios morfológicos, anatómicos y análisis con microscopia electrónica de barrido. La longevidad y dinámica de exposición de las papilas estigmáticas y la secuencia de liberación de los granos de polen en los cuatro estambres fueron observados para verificar el grado de dicogamia. El sistema reproductivo se evaluó mediante el test de autopolinización espontánea y polinización abierta. Los visitantes florales fueron identificados y se registró su frecuencia de visita. Piper caldense presenta flores bisexuales y estaminadas, cada tipo floral se encuentra en espigas separadas. Estas espigas se encuentran en la misma planta, lo que indica que es andromonoica; adicionalmente, fueron observadas plantas que solo presentaban espigas con flores estaminadas, lo que se constituye en una combinación sexual inédita para el género. La exposición gradual y secuencial de las papilas estigmáticas asociada con la liberación asincrónica de los granos de polen (un estambre por día) indica una protoginia incompleta. Los test de polinización mostraron que la especie es autoincompatible. Las abejas sociales, principalmente Apis mellifera y Melipona spp., fueron los polinizadores principales. Este estudio refuerza la necesidad de asociar los analisis morfológicos con la funcionalidad de las estructuras florales, además indica los cambios futuros en estudios que abordan características reproductivas asociadas a la filogenia de las especies de Piper.
ABSTRACT
O objetivo foi avaliar a fenologia reprodutiva e as síndromes de polinização e dispersão de um subbosque de Mata Seca Semidecídua. O estudo foi realizado na cidade de Catalão-GO, de maio de 2010 a maio de 2011, no Parque Municipal do Setor Santa Cruz, um fragmento de 29 hectares. A coleta dos dados fenológicos foi semanal utilizando um transecto de 1000 m. Para as síndromes, foi observado à morfologia de flores e frutos, e estes dados foram relacionados aos de fenologia. A floração teve maior índice (43,13%) em dezembro de 2010 (chuva) e a frutificação manteve índices de 25 a 30% na maior parte do ano. Acanthaceae apresentou o maior índice de floração em maio de 2010 e fevereiro de 2011; Piperaceae em outubro de 2010 e Rubiaceae em dezembro 2010. A frutificação em Acanthaceae ocorreu durante a seca e inicio das chuvas, com maior índice em outubro de 2010, Piperaceae na estação das chuvas e inicio da seca, com pico em maio de 2011, e em Rubiaceae ocorreu durante 11 meses, com pico em março de 2011. Duas espécies de Acanthaceae e uma de Piperaceae não apresentaram frutificação, já a fenofase de floração foi observada nessas espécies. Foram identificadas três síndromes de polinização, sendo estas melitofilia (pico de intensidade em outubro de 2010), psicofilia (janeiro de 2011) e ornitofilia (maio de 2010). As síndromes de dispersão foram ornitocoria (dois picos, um em julho de 2010 e outro em maio de 2011) e anemocoria (pico em outubro de 2010). A presença de espécies em floração e/ou frutificação ao longo do ano pode contribuir para a dinâmica e permanência da comunidade estudada, pois essas espécies auxiliam na manutenção de abelhas e aves no fragmento, importantes vetores de polinização e dispersão. Levando em consideração que o Cerrado vem sofrendo um intenso impacto ambiental e a área de estudo ser um fragmento localizado dentro de um perímetro urbano, a sua conservação torna-se de grande importância, apesar de sua pequena área, devido os importantes processos ecológicos que ali existem.
The objective was to identify the reproductive phenology and the pollination and dispersal syndromes of understory species of Semi-deciduous Dry Forest. The work was carried out from May 2010 to May 2011 in a forest fragment, about 29 hectares, localized in Catalão city, Goiás State, Brazil. The phenological phases were observed weekly along a transect at 1000m. Pollination and dispersion syndromes were determined through literature data, and theses data were linked to phenology. The flowering proportion reached the peak (43,13%) in December 2010 (rainy) and fruiting (30%) in September 2010 (dry). Acanthaceae flowering peak in May 2010 and February 2011; Piperaceae peaked in October 2010 and Rubiaceae in December 2010. Fruiting in the Acanthaceae occurred during the dry period and the beginning of the rainy season, with the highest incidence in October 2010, Piperaceae reached their peak in May 2011, while in the Rubiaceae, it went on for 11 months, with the highest incidence being in March 2011. Two Acanthaceae and one Piperaceae species not fruited, but all species presented flowering. Pollination syndromes found were Ornithophily, peaking in May 2010, Melittophily, in October 2010, and Psycophily, in January 2011. Dispersal syndromes found were Anemochoric, with a higher incidence in October 2010, and Ornithocoric with two peaks, one in July 2010 and other in May 2011. The year-long presence of flowering and/or fruiting species contributes to the survival and dynamics of the community studied, because these species play an important role maintaining bees and birds in the fragment, which are important vectors of pollination and dispersal, respectively. Considering the rapid loss of the Cerrado vegetation in recent times and the study site to be a fragment localized inside the urban environment, the conservation of the green area becomes important, regardless of its small size, due to the important ecological processes that lie therein, as portrayed in this study.
Subject(s)
Pollination , Plant Dispersal , Reproduction , ForestsABSTRACT
Pollen dispersion and reproductive success of four tree species of a xerophytic forest from Argentina. The "talares" in eastern Buenos Aires province, Argentina, are coastal xerophitic forests structured by few arboreal species surrounded by a lower and moister soil matrix. We studied the reproductive parameters of the most representative arboreal species (Celtis tala, Scutia buxifolia, Jodina rhombifolia,and Schinus longifolia). Pollen dispersion was studied through floral visitor traps (biotic dispersion) and using gravimetric pollen collectors (abiotic dispersion). The reproductive success (fruit formation rate) of the focal species was studied by enclosing flowers with different mesh bags. The reproductive system varied among the different species. C. tala was anemophilous and selfcompatible. S. buxifolia was entomophilous and floral visitors dependant. J. rhombifolia was entomophylous, although spontaneous autogamy could favor reproduction in the absence of pollinators. Lastly, S. longifolia could be an ambophilous species (pollinated by insects and by the wind). This dual system may be the result of system flexibility mechanism or an evolutionary transition. Rev. Biol. Trop. 57 (1-2): 283-292. Epub 2009 June 30.
Los "talares" del E de la provincia de Buenos Aires son bosques xerófitos costeros estructurados por pocas especies arbóreas rodeados de una matriz de suelos más bajos y húmedos. Estudiamos los parámetros reproductivos de las especies arbóreas más representativas (Celtis tala, Scutia buxifolia, Jodina rhombifolia y Schinus longifolia). La dispersión polínica fue estudiada a través de trampas para visitantes florales (dispersión biótica) y utilizando recolectores gravimétricos de polen (dispersión abiótica). El éxito reproductivo (tasa de formación de frutos) de las especies focales fue estudiado a través de embolsado de flores con bolsas de distintos tipos de malla. El sistema reproductivo varió entre las especies. C. tala resultó anemófila y autocompatible, S. buxifolia fue entomófila y dependiente de los visitantes florales. J. rhombifolia fue una especie entomófila, aunque la autogamia espontánea podría favorecer al aseguramiento reproductivo en caso de falta de polinizadores. Finalmente, S. longifolia podría ser una especie ambófila (polinizada por insectos y por el viento). Este sistema dual podría ser el resultado de un mecanismo de flexibilidad del sistema de polinización o una transición evolutiva.