Wild Vanilla and pollinators at risk of spatial mismatch in a changing climate

Abstract

Climate change is expected to drive substantial shifts in species' geographic ranges. Species-specific responses of interacting species, such as plants and their pollinators, may lead to a spatial mismatch in their future distributions, disrupting these interspecific interactions. The crop wild relatives (CWRs) of the tropical cash crop vanilla hold valuable genetic resources for use in crop breeding, but their persistence is dependent on the presence of their pollinators, and at risk due to several anthropogenic pressures including climate change. To contribute to the safeguarding of this wild Vanilla gene pool, the present study aims at better understanding the effects of climate change on Vanilla species and their pollinators, and to identify potential spatial mismatches between both. Focusing on the Neotropical realm, we used MaxEnt species distribution models (SDMs) to predict potential changes in the range overlap between Vanilla and their pollinators by 2050 under the SSP2-4.5 and SSP3-7.0 climate change scenarios. We were able to compile enough occurrence records to generate SDMs for 11 Neotropical Vanilla CWRs, of which data on pollinator identity was available for four animal-pollinated species. Our models showed varying results among Vanilla species, with some predicted to undergo a net contraction (-1% to -53%) and others predicted to experience a net expansion (+11 to +140%), while the area of suitable habitat for all pollinators was predicted to decline (-7% to -71%). Our models predict a decline in range overlap between animal-pollinated Vanilla species and their pollinators under climate change, and this spatial mismatch was more pronounced for species reliant on a single known pollinator (-60% to -90%). Furthermore, the proportion of overlapping ranges located within protected areas is predicted to shrink for all species if no action is taken. Based on these findings, we propose priority areas for in situ and ex situ conservation to safeguard Vanilla's genetic resources.

Keywords: Euglossini; Orchidaceae; climate change; ex situ conservation; in situ conservation; plant-pollinator decoupling; species distribution models; vanilla crop wild relatives.

Figure 1

Predicted changes in suitable habitat by 2050 under the “middle of the road” (SSP2-4.5) and “regional rivalry” (SSP3-7.0) scenarios for the 11 modeled Vanilla species and seven pollinator species. Calculations were made considering the area encompassed by the convex hulls around the presence points of the modeled species (see 2.1.3).

Figure 2

Maps showing the range overlap between animal-pollinated Vanilla species and their corresponding pollinator(s) under present climate conditions (left) and predicted climate change scenarios SSP2-4.5 (middle) and SSP3-7.0 (right) for 2050. Projections were made for the entire geographical extent of (sub)tropical America but interpretation was restricted to the area encompassed by the convex hulls (red dotted line) under the assumption that models are extrapolated more outside these hulls. Areas outside the hulls were given a lighter color.

Figure 3

Map indicating currently protected areas where the range of a Vanilla species and its pollinator(s) was predicted to overlap in 2050 (dark brown), currently unprotected areas with a predicted range overlap between a Vanilla species and its pollinator(s) in 2050, which could be prioritized new conservation areas (light brown), and areas that harbor populations that may need ex situ conservation or assisted migration as they are found in areas that are predicted to become unsuitable by 2050 (blue). We used the species V. pompona and the SSP2-4.5 scenario as an example.