Biología
https://hdl.handle.net/10669/273
2024-03-19T04:23:54ZSpecific leaf area (SLA) serves as a proxy to predict total carbon content in understory individuals of the neotropical canopy palm Socratea exorrhiza
https://hdl.handle.net/10669/91004
Specific leaf area (SLA) serves as a proxy to predict total carbon content in understory individuals of the neotropical canopy palm Socratea exorrhiza
Evaluating intraspecifc and ontogenetic variation in SLA is critical to understand how functional traits infuence plant ftness and regeneration strategies. SLA is usually expressed as an average value per species. Its variation across
ontogenetic stages and environmental gradients is poorly known, particularly in palms. I measured SLA in 112 palms of
Socratea exorrhiza in the understory of a tropical rainforest in Costa Rica. Total carbon content sequestered per palm (kg)
was estimated from an allometric equation. I determined the regression between Ln SLA and Ln carbon content, and then
used principal components to summarize the regeneration strategy of S. exorrhiza by examining the allometry of stem length
and diameter, number of fronds, number of stilt roots, stilt root cone height, slenderness ratio, SLA, and carbon content. SLA
predicted total sequestered carbon (slope = −4.33, r
2=0. 52). Smaller values of SLA were associated with increased carbon
content and larger palms. Two components explained 77% of the variation in functional traits. The frst (76%) was dominated
by stem diameter, height, stilt root cone, and carbon content (negatively associated with SLA) and refected palm size; the
second (15%) was dominated by slenderness ratio and number of leaves and refected allocation to growth in height. The
inverse relationship between SLA and sequestered carbon is consistent with the initial shade tolerant, conservative resource
use strategy of S. exorrhiza.
2023-01-01T00:00:00ZReporte de capturas de aves en el páramo del Cerro Buena Vista, Costa Rica
https://hdl.handle.net/10669/90999
Reporte de capturas de aves en el páramo del Cerro Buena Vista, Costa Rica
El objetivo de esta nota es reportar la captura
de 13 especies de aves en el páramo del Cerro
Buena Vista de Febrero del 2017, a Enero del
2018. Ya que la progresión del cambio climático
está avanzando más rápidamente de lo esperado es importante generar los datos necesarios que
sirvan de comparación con estudios futuros a
fin de determinar cómo la biota tropical de alta
montaña responde a este proceso.
El sitio de estudio corresponde al páramo
del Cerro Buena Vista (09º33’N- 83º45’O), 3,380
msnm, cerca del kilómetro 89 de la Carretera
Interamericana Sur. En esta zona existe cierto
grado de intervención ya que muchas áreas de
vegetación se cortan para mantener senderos de
acceso a las antenas del Instituto Costarricense
de Electricidad (ICE). Cada mes durante el
periodo de muestreo colocamos 2-3 redes de
niebla de 12 x 2.5 m durante 2-3 días, las que
se mantuvieron abiertas entre las 07:00 y las
17:00 horas. Las redes se cerraron cuando
se presentaron condiciones lluviosas. Si bien
nuestra investigación principal estaba centrada
en determinar la carga de polen de colibríes,
registramos todas las especies de aves capturadas
en redes.
2019-01-01T00:00:00ZSelfing in epiphytic bromeliads compensates for the limited pollination services provided by nectarivorous bats in a neotropical montane forest
https://hdl.handle.net/10669/90993
Selfing in epiphytic bromeliads compensates for the limited pollination services provided by nectarivorous bats in a neotropical montane forest
Plants with specialized pollination systems frequently exhibit adaptations for self-pollination, and this contradictory situation has been explained in terms of the reproductive assurance function of selfing. In the Neotropics, several plant lineages rely on specialized vertebrate pollinators for sexual reproduction, including the highly diverse Bromeliaceae family, which also displays a propensity for selfing. Thus far, the scarce evidence on the role of selfing in bromeliads and in other neotropical plant groups is inconclusive. To provide insights into the evolution and persistence of self-fertilization in the breeding systems of Bromeliaceae, we studied four sympatric epiphytic species from the genus Werauhia (Tillandsioideae) in Costa Rica. We documented their floral biology, pollination ecology, and breeding systems. We estimated the contribution of selfing by comparing the reproductive success between emasculated flowers requiring pollinator visits and unmanipulated flowers capable of selfing and exposed to open pollination across two flowering seasons. The studied species displayed specialized pollination by nectar-feeding bats as well as a high selfing ability (autofertility index values > 0.53), which was attained by a delayed selfing mechanism. Fruit set from natural cross-pollination was low (<26% in both years) and suggested limited pollinator visitation. In line with this, we found a very low bat visitation to flowers using video-camera recording, from 0 to 0.24 visits per plant per night. On the contrary, the contribution of selfing was comparatively significant since 54-80% of the fruit set from unmanipulated flowers can be attributed to autonomous self-pollination. We concluded that inadequate cross-pollination services diminished the reproductive success of the studied Werauhia, which was compensated for by a delayed selfing mechanism. The low negative effects of inbreeding on seed set and germination likely reinforce the persistence of selfing in this bromeliad group. These results suggest that selfing in bat-pollinated bromeliads may have evolved as a response to pollinator limitation.
2024-02-01T00:00:00ZEfecto de la longitud del pico sobre la especialización de la visitación floral de colibríes de zonas medias y altas de Costa Rica
https://hdl.handle.net/10669/90991
Efecto de la longitud del pico sobre la especialización de la visitación floral de colibríes de zonas medias y altas de Costa Rica
Los colibríes desempeñan un papel crucial en las redes de polinización, ya que su visita a los
recursos florales puede determinar el éxito reproductivo de las plantas. En este estudio, hemos investigado
cómo las diferencias en la longitud del pico de los colibríes, tanto dentro como entre especies, afectan la
diversidad de uso de los recursos florales. Las especies con picos cortos estarán restringidas principalmente a
visitar plantas con corolas cortas, mientras que las especies con picos largos tienen la capacidad de visitar un
mayor rango de tamaños de corolas, lo que las convierte en especies más generalistas. En el caso de los colibríes
con dimorfismo sexual en la longitud del pico, se espera que el sexo con el pico más largo sea el más generalista.
El estudio se llevó a cabo en el Hotel Bougainvillea (1.200 msnm, 10 especies de plantas y 5 de colibríes, 259
interacciones) y en el restaurante La Georgina (3.100 msnm, 7 especies de plantas y 4 de colibríes, 307
interacciones), en Costa Rica. En ambos lugares se obtuvieron redes de polinización de diferente estructura y
complejidad que mostraron una tendencia hacia la especialización (índice de conectancia Bougainvillea = 0.30,
IC Georgina = 0.42); nivel de especialización de la red H2 Bougainvillea = 0.5, H2 La Georgina = 0.70). A medida
que aumentó la longitud del culmen, disminuyó el grado de especialización, lo cual respaldó nuestra hipótesis.
En el caso de Eugenes spectabilisse las hembras tuvieron picos más largos y posiblemente son más generalistas
que los machos. Las hembras son excluidas de los comederos y posiblemente tengan que cubrir mayores
territorios en busca de recursos más diversos. Se requiere más investigación centrada en esta especie para
obtener resultados más concluyentes.; Hummingbirds play a crucial role in pollination networks, as their visit to floral resources can
determine plant reproductive success. We investigated how differences in bill length of hummingbirds, within and between species, affect the range of use of floral resources. Species with short bills will be mainly restricted
to visiting plants with short corollas, while species with long bills could visit awider range of corolla sizes, making
them more generalist. In the case of hummingbirds with sexual dimorphism in bill length, it is expected that
the sex with the longer bill will be the most generalist. The study was conducted at Hotel Bougainvillea (1,200
masl, 10 plant and 5 hummingbird species, 259 interactions) and at the restaurant La Georgina (3,100 masl, 7
plant and 4 hummingbird species, 307 interactions) in Costa Rica. In both locations, we obtained pollination
networks with different structure and complexity that showed a tendency towards specialization (Bougainvillea
connectance index = 0.30, IC Georgina = 0.42; specialization at the network level H2 Bougainvillea = 0.5 and La
Georgina H2 = 0.70). As bill length increased, the degree of specialization decreased, which supported our
hypothesis. In the case of Eugenes spectabilis, females had longer bills and are possibly more generalist than
males since they are excluded from feeders and may have to cover larger territories in search of more diverse
resources. Further research focused on this species is needed to obtain more conclusive results.
2023-01-01T00:00:00Z