Antilles

Abstract

Aim: Mutualistic interactions between plants and animals are fundamental for the maintenance of natural communities and the ecosystem services they provide. However, particularly in human-dominated island ecosystems, introduced species may alter mutualistic interactions. Based on an extensive dataset of plant–frugivore interactions, we mapped and analysed a meta-network across the Caribbean archipelago. Specifically, we searched for subcommunity structure (modularity) and identified the types of species facilitating the integration of introduced species in the Caribbean meta-network.

Location: Caribbean archipelago (Lucayan archipelago, Greater Antilles, Lesser Antilles).

Methods: We reviewed published scientific literature, unpublished theses and other nonpeer-reviewed sources to compile an extensive dataset of plant–frugivore interactions. We visualized spatial patterns and conducted a modularity analysis of the cross-island meta-network We also examined which species were most likely to interact
with introduced species: (1) endemic, nonendemic native or introduced species, and (2) generalized or specialized species.

Results: We reported 3060 records of interactions between 486 plant and 178 frugivore species. The Caribbean meta-network was organized in 13 modules, driven by a combination of functional or taxonomic (modules dominated by certain groups of frugivores) and biogeographical (island-specific modules) mechanisms. Few introduced species or interaction pairs were shared across islands, suggesting little homogenization of the plant–frugivore meta-network at the regional scale. However, we found evidence of “invader complexes,” as introduced frugivores were more likely to interact with introduced plants than expected at random. Moreover, we found generalist
species more likely to interact with introduced species than were specialized species.

Main conclusions: These results demonstrate that generalist species and “invader complexes” may facilitate the incorporation of introduced species into plant–frugivore communities. Despite the influx of introduced species, the meta-network was structured into modules related to biogeographical and functional or taxonomic affinities. These findings reveal how introduced species become an integral part of mutualistic systems on tropical islands.

Abstract
Tropical dry forests experience pronounced seasonal changes in precipitation mani- 
fested in varied plant phenologies. At landscape scales, geologic substrate—one of the 
least understood abiotic factors interacting with precipitation—may modulate phe- 
nological responses in these forests through a combination of mechanisms regulat- 
ing water and nutrient use. We leveraged a phenological dataset from the semiarid 
island of Curaçao to examine the extent to which plant phenology at multiple levels 
of biological organization diverge under different geologies. Monthly observations 
over a 30-month period of leaves, flowers, and fruits of 69 plant species of different 
life forms at three nearby sites differing in their underlaying geology were used to 
examine intra- and inter-annual plant responses at species, community, and system 
levels. The integration of leaf, flower, and fruit observations at intra-annual scales 
revealed diverse phenological strategies among species, broad associations with geo- 
logic substrate, and the extent of intra-specific variation as a function of geology. The 
community- and system-level analyses at inter-annual scales showed a reduction in 
mean leaf scores during the 30-month period, a weak and strong leafless period in 
1993 and 1994, respectively, and differences among geologic substrates. Finally, we 
observed significant and positive relationships between precipitation and the pheno- 
phase scores; the strength of the relationships varied with phenophase and geologic 
substrate. Results of this work emphasize the importance of geologic substrate, and 
more broadly speaking landscape heterogeneity, in modulating plant phenological re- 
sponses in tropical dry forests. Ultimately, this information will become important to 
understand and mitigate global climate change impacts.
Abstract in Spanish is available with online material.

Abstract:

The original description of Ipomoea sphenophylla by Urban in 1908, based upon a fruiting specimen, did not include a description of the flowers. The holotype was subsequently lost and plants in flower were recol- lected in 1994; a neotype was then designated by Howard and McDonald in 1995. An amended description of the species was also supplied, detailing the characteristics of the cotyledons, a swollen root system, and dimorphic flowers. The flowers were described as including a more common morph with a normal funnelform corolla, and an abnormal morph having a 3–5 polypetalous corolla. Presently, both morphs occur together on one sterile indi- vidual that is located in the area where the neotype was collected. We have examined approximately 150 addi- tional plants, and all contain funnelform flowers. The polypetalous morphology is therefore atypical of Ipomoea sphenophylla. The species description is emended and the reference to polypetalous flowers is removed.