Factors affecting nectar sugar composition in chiropterophilic plants

AbstractMost pollinators prefer the sugars present in the nectar they consume, so it has been hypothesized that they have molded nectar trait evolution. However, nectar-feeding bats do not exhibit preferences for the sugars present in their diet. We analyzed the role that biochemical and ecological factors could play in shaping the nectar traits of chiropterophilic plants. We studied nectar traits and flower production in 49 plant species. We evaluated the relationship between nectar concentration and sugar composition using phylogenetically independent contrasts and if nectar traits were related to flower production using a Manova. We found that 42 species produced high hexoses nectars, and 7 species produced sucrose rich nectars. Phylogenetically independent contrasts showed that nectar concentration was negatively related to glucose content, positively related to fructose content, and was not related to sucrose content. A negative relationship was found from glucose and fructose contents to sucrose content, and glucose content was negatively related to fructose content. Finally, we did not found any relationship between nectar traits and the plants’ flowering strategies. We conclude that bat physiology and the relative low evolutionary time of the interaction between plants and bats may determine the lack of pattern in the nectar characteristics of chiropterophilic plants

Efecto de la perturbación del bosque en la tasa de visitas de murciélagos polinizadores y sus consecuencias sobre el éxito reproductivo y sistema de apareamiento en árboles de la familia Bombacaceae.

La fragmentación y la perturbación del bosque pueden tener efectos deletéreos sobre el éxito reproductivo y el sistema de apareamiento de los árboles tropicales, además de modificar el compartimiento de sus polinizadores. Los objetivos de este capítulo son: (1) evaluar el efecto de la perturbación del bosque sobre la tasa de visita de los murciélagos a cuatro especies de árboles de Bombacaceas; (2) comparar el éxito reproductivo entre árboles en áreas perturbadas y en bosques continuos; (3) determinar las consecuencias de un cambio en la tasa de visitas de los polinizadores sobre el éxito reproductivo de los árboles; y (4) documentar cómo los patrones de visita de los polinizadores pueden afectar el sistema de apareamiento de las plantas que polinizan. Se estudiaron cuatro especies de árboles de la familia Bombacaceae en los bosques tropicales de Jalisco, México, y en las regiones de Guanacaste y la Península de Osa, en Costa Rica. Los murciélagos nectarívoros fueron los únicos polinizadores efectivos para estas cuatro especies. Las flores de Ceiba grandiflora en el bosque recibieron más visitas por parte de Glossophaga soricina; no se observaron diferencias en el número de visitas por parte de Leptonycteris curasoae y Musonycteris harrisoni solo visitó flores dentro del bosque. Ceiba aesculifolia presentó una mayor tasa de visitas en los sitios perturbados, tanto por G.. soricina como por L. curasoae. Ceiba pentandra, en Chamela, no presentó diferencias en la tasa de visitas de G. soricina entre áreas perturbadas y bosque continuo, pero L. curasoae visitó una mayor cantidad de flores en bosque continuo. En Guanacaste, C. pentandra recibió más visitas de Phyllostomus discolor que de G presentó una mayor producción de flores en fragmentos y no hubo diferencias en la proporción de frutos por flor (fruto/flor). Ceiba grandiflora no presentó diferencias en la producción de flores, pero la razón fruto/flor fue mayor en el bosque. Pachira quinata presentó un patrón similar a C. aesculifolia en cuanto a la producción de flores, pero la razón fruto/flor fue mayor en los árboles de bosque continuo. Estas cuatro especies de Bombacaceae son predominantemente autoincompatibles. Los niveles de exocruzamiento fueron independientes del tipo de hábitat para C. aesculifolia, C. grandiflora y C. pentandra en Guanacaste; sin embargo, los árboles C. pentandra, en la Península de Osa, mostraron un sistema de apareamiento mixto. Los efectos de la perturbación del bosque sobre la polinización por murciélagos, la reproducción de plantas y sus patrones de apareamiento varían según la especie de Bombacaceae y su historia de vida.Forest fragmentation and disturbance can have negative effects on the reproductive success and mating systems of tropical trees, in addition to modifying the behavior of the pollinators that pollinate them. The objectives of this study are: (1) to evaluate the effect of forest disturbance on bat pollinator activity for four bombacaceous species; (2) to compare reproductive success between trees found in disturbed habitats and continuous forest; (3) to determine the consequences of a change in bat pollinator activity on plant reproductive success; and (4) to document how bat pollinator activity may affect breeding systems in the plants they pollinate. Four species from the Bombacaceae family were studied in the tropical forests of Jalisco, Mexico, and in the areas of Guanacaste and Peninsula de Osa, in Costa Rica. Nectarivorous bats were the only effective pollinators observed for these four species. Flowers from Ceiba grandiflora in the forest received more visits from Glossophaga soricina. No differences were observed for Leptonycteris curasoae and Musonycteris harrisoni was only observed visiting flowers in the forest. Flowers from C. aesculifolia in fragmented habitats received more visits from both G. soricina and L. curasoae. For C. pentandra in Chamela no differences in visits were observed for G. soricina between disturbed areas and continuous forest, but L. curasoae visited more flowers in continuous forest. In Guanacaste, C. pentandra received more visits from Phyllostoumus discolor than G. soricina, and in Osa no bat visits were observed. Ceiba aesculifolia produced more flowers in disturbed areas but no differences were observed for fruit set. Ceiba grandiflora showed no differences in flower production but fruit set was greater in the forest. Similar to C. grandiflora, Pachira quinata showed no differences in flower production, however, greater fruit set was observed in continuous forest. These four bombacaceous species are predominantly self-incompatible. Out-crossing rates were independent of habitat for C. aesculifolia, C. grandiflora, and C. pentandra en Guanacaste; however, C. pentandra trees from the Osa Peninsula showed a mixed breeding system. Our results show that the effects of forest disturbance on bat pollination, plant reproductive success and breeding system varied depending on the bombacaceous species and its life history characteristics.UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí

Phylogenetic classification of the world's tropical forests

Knowledge about the biogeographic affinities of the world’s tropical forests helps to better understand regional differences in forest structure, diversity, composition, and dynamics. Such understanding will enable anticipation of region-specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present a classification of the world’s tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: (i) Indo-Pacific, (ii) Subtropical, (iii) African, (iv) American, and (v) Dry forests. Our results do not support the traditional neo- versus paleotropical forest division but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar, and India. Additionally, a northern-hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northern-hemisphere forests.</p

Patch Size and Isolation Predict Plant Species Density in a Naturally Fragmented Forest

<div><p>Studies of the effects of patch size and isolation on plant species density have yielded contrasting results. However, much of the available evidence comes from relatively recent anthropogenic forest fragments which have not reached equilibrium between extinction and immigration. This is a critical issue because the theory clearly states that only when equilibrium has been reached can the number of species be accurately predicted by habitat size and isolation. Therefore, species density could be better predicted by patch size and isolation in an ecosystem that has been fragmented for a very long time. We tested whether patch area, isolation and other spatial variables explain variation among forest patches in plant species density in an ecosystem where the forest has been naturally fragmented for long periods of time on a geological scale. Our main predictions were that plant species density will be positively correlated with patch size, and negatively correlated with isolation (distance to the nearest patch, connectivity, and distance to the continuous forest). We surveyed the vascular flora (except lianas and epiphytes) of 19 forest patches using five belt transects (50×4 m each) per patch (area sampled per patch = 0.1 ha). As predicted, plant species density was positively associated (logarithmically) with patch size and negatively associated (linearly) with patch isolation (distance to the nearest patch). Other spatial variables such as patch elevation and perimeter, did not explain among-patch variability in plant species density. The power of patch area and isolation as predictors of plant species density was moderate (together they explain 43% of the variation), however, a larger sample size may improve the explanatory power of these variables. Patch size and isolation may be suitable predictors of long-term plant species density in terrestrial ecosystems that are naturally and anthropogenically fragmented.</p></div

Log linear models proposed to explain the variation in plant species density (S) in 19 forest patches on the Yucatan Peninsula.

<p>Log linear models proposed to explain the variation in plant species density (S) in 19 forest patches on the Yucatan Peninsula.</p

Relationship between plant species density (number of species in 0.1 ha) and patch size (Size) (A) and between plant species density and the distance to the nearest patch (B) for a group of 19 forest patches on the Yucatan Peninsula.

<p>Regression lines for A and B are also shown. The scale on the “x” axis for A is logarithmic.</p

Number of species observed in 0.1 ha samples (S) and predicted number of plant species using three nonparametric estimators (Chao1, ACE and Bootstrap) for 19 forest patches on the Yucatan Peninsula.

<p>Number of species observed in 0.1 ha samples (S) and predicted number of plant species using three nonparametric estimators (Chao1, ACE and Bootstrap) for 19 forest patches on the Yucatan Peninsula.</p

Data from: Pollinator-mediated interactions between cultivated papaya and co-flowering plant species

Many modern crop varieties rely on animal pollination to set fruit and seeds. Intensive crop plantations usually do not provide suitable habitats for pollinators so crop yield may depend on the surrounding vegetation to maintain pollination services. However, little is known about the effect of pollinator-mediated interactions among co-flowering plants on crop yield or the underlying mechanisms. Plant reproductive success is complex, involving several pre- and post-pollination events; however, the current literature has mainly focused on pre-pollination events in natural plant communities. We assessed pollinator sharing and the contribution to pollinator diet in a community of wild and cultivated plants that co-flower with a focal papaya plantation. In addition, we assessed heterospecific pollen transfer to the stigmatic loads of papaya and its effect on fruit and seed production. We found that papaya shared at least one pollinator species with the majority of the co-flowering plants. Despite this, heterospecific pollen transfer in cultivated papaya was low in open-pollinated flowers. Hand pollination experiments suggest that heterospecific pollen transfer has no negative effect on fruit production or weight, but does reduce seed production. These results suggest that co-flowering plants offer valuable floral resources to pollinators that are shared with cultivated papaya with little or no cost in terms of heterospecific pollen transfer. Although HP reduced seed production, a reduced number of seeds per se is not negative, given that from an agronomic perspective the number of seeds does not affect the monetary value of the papaya fruit

Ecological knowledge, use and management of maax ik (<em>Capsicum annuum</em> var. <em>glabriusculum</em> (Dunal) Heiser & Pickersgill) in a rural Mayan community

Background: Capsicum annuum var. glabriusculum is the ancestor of most of the economically important chiles in the world. It is widely distributed throughout Mexico, and currently all indigenous groups interact with this plant species. On the Yucatan Peninsula wild chile is known as maax ik by the Maya. Although this area has been recognized as a domestication and diversification center of chile, ethnobotanical research on this species is still limited.      Questions: What ecological knowledge do local people have about maax ik? Where and how is maax ik gathered and managed? What uses does maax ik currently have? Studied species: Capsicum annuum var. glabriusculum Study site and dates: San Bernardo, Yucatan. Summer-Autumn 2021. Methods: In-depth semi-structured interviews and participatory observation. The management practices were identified, and management intensity was estimated. Results: Informants knew that maax ik reproduces sexually and recognized the role of birds in its seed dispersal. Maax ikwas mainly gathered from homegardens where this species was tolerated and other non-selective incipient management practices such as protection and promotion were also carried out. Fruit was harvested without harming the plant and only a small portion of the available fruit was usually taken. The informants used maax ik essentially as food. The management intensity index was relatively high (5). Conclusions: Maax ik is a sustenance food resource that is sustainably used and non-selectively managed in homegardens by our informants in San Bernardo, Yucatan

Partial and asymmetrical reproductive isolation between two sympatric tropical shrub species: Cnidoscolus aconitifolius and C. souzae (Euphorbiaceae)

Abstract Reproductive isolation is conferred by several barriers that occur at different stages of reproduction. Comprehensive reviews on the topic have identified that barriers occurring prior to zygote formation are often stronger than those that occur afterward. However, the overrepresentation of temperate perennial herbs in the current literature precludes any generalization of this pattern to plants that present other life forms and patterns of distribution. Here, we assessed reproductive isolation barriers and their absolute contribution to reproductive isolation and asymmetry in Cnidoscolus aconitifolius and C. souzae, two closely related tropical shrub species that co‐occur on the Yucatan peninsula. The reproductive barriers assessed were phenological mismatch, pollinator differentiation, pollen–pistil incompatibility (three pre‐zygotic barriers), fruit set failure, and seed unviability (post‐zygotic barriers). Reproductive isolation between the study species was found to be complete in the direction C. aconitifolius to C. souzae, but only partial in the opposite direction. One post‐zygotic barrier was the strongest example. Most barriers, particularly the pre‐zygotic examples, were asymmetrical and predicted the direction of heterospecific pollen flow and hybrid formation from C. souzae to C. aconitifolius. Both parental species, as well as the hybrids, were diploid and had a chromosome number 2n = 36. More studies with tropical woody perennials are required to fully determine whether this group of plants consistently shows stronger post‐zygotic barriers