Pollination ecology and breeding system of the tropical tree Guaiacum sanctum on two Caribbean islands with contrasting pollinator assemblages

Authors

  • Jose J. Fumero-Caban Universidad Ana G Mendez https://orcid.org/0000-0002-2112-1114
  • Elvia J. Melendez-Ackerman Department of Environmental Sciences, College of Natural Sciences, University of Puerto Rico, Rio Piedras Campus, 17 Ste Ave Universidad 1701, San Juan, P.R. 00925
  • Julissa Rojas-Sandoval https://orcid.org/0000-0001-6620-4741

DOI:

https://doi.org/10.26786/1920-7603(2022)669

Keywords:

alien pollinators; Apis mellifera; native bees; plant-insect interaction; subtropical dry forest; reproductive biology

Abstract

Insular pollination systems are more extinction-prone and vulnerable to invasive species than mainland ones. They often have plants with reproductive mechanisms allowing for self-compatibility and low species-rich communities of pollinators. Here, we document different reproductive traits of the tropical tree Guaiacum sanctum on two insular populations with contrasting pollinator assemblages: Guánica in Puerto Rico with alien honeybees and Mona Island where honeybees do not occur. Using field observations and pollination experiments, we evaluated pollinator species richness, visitation rates, breeding system, and the fitness of selfed- vs. crossed-progenies. We found that flowers are pollinated by insects on both islands, but while the species richness of pollinators was higher on Mona, the visitation rates were considerably higher in Guánica where trees are almost exclusively visited by the introduced Apis mellifera. Flowers are not apomictic, and autogamy is negligible indicating that pollinators are required to set fruits. Outcrossing yielded nearly twice the number of fruits and seeds than selfing and these differences were consistent between populations, which might reflect early acting inbreeding depression, partial self-incompatibility, or differences in resource allocation between selfed and outcrossed fruits. Our combined results suggest that the substantial reduction in pollinator visitors in areas dominated by A. mellifera may add an additional level of vulnerability to these threatened populations. Although reproductive fitness is higher in Guánica, mostly due to the pollination services provided by A. mellifera, this population may be more susceptible to environmental changes and large-scale disturbances affecting pollinator abundance given the reduced diversity of flower visitors.

Author Biographies

Jose J. Fumero-Caban, Universidad Ana G Mendez

 

 

Elvia J. Melendez-Ackerman, Department of Environmental Sciences, College of Natural Sciences, University of Puerto Rico, Rio Piedras Campus, 17 Ste Ave Universidad 1701, San Juan, P.R. 00925

 

 

Julissa Rojas-Sandoval

 

 

Published

2022-09-21

How to Cite

Fumero-Caban, J. J., Melendez-Ackerman, E. J., & Rojas-Sandoval, J. (2022). Pollination ecology and breeding system of the tropical tree Guaiacum sanctum on two Caribbean islands with contrasting pollinator assemblages. Journal of Pollination Ecology, 31, 139–153. https://doi.org/10.26786/1920-7603(2022)669

Issue

Section

Early View