Data from: The ecology and evolution of seed predation by Darwin's finches on Tribulus cistoides on the Galápagos Islands
- Description:
- Predator-prey interactions play a key role in the evolution of species traits through antagonistic coevolutionary arms-races. The evolution of beak morphology in the Darwin’s finches in response to competition for seed resources is a classic example of evolution by natural selection. The seeds of Tribulus cistoides are an important food source for the largest ground finch species (Geospiza fortis, G. magnirostris, and G. conirostris) in dry months, and the hard spiny morphology of the fruits are a potent agent of selection that drives contemporary evolutionary change in finch beak morphology. Although the effects of these interaction on finches are well known, how seed predation affects the ecology and evolution of the plants is poorly understood. Here we examine whether seed predation by Darwin’s finches affects the ecology and evolution of T. cistoides. We ask whether the intensity of seed predation and the strength of natural selection by finches on fruit defense traits varies among populations, islands, years, or with varying finch community composition (i.e., the presence/absence of the largest beaked species, which feed on T. cistoides most easily). We then further test whether T. cistoides fruit defenses have diverged among islands in response to spatial variation in finch communities. We addressed these questions by examining seed predation by finches in 30 populations of T. cistoides over three years. Our study reveals three key results. First, Darwin’s finches strongly influence T. cistoides seed survival, whereby seed predation varies with differences in finch community composition among islands and in response to inter-annual fluctuations in precipitation. Second, finches impose phenotypic selection on T. cistoides fruit morphology, whereby smaller and harder fruits with longer or more spines exhibited higher seed survival. Variation in finch community composition and precipitation also explains variation in phenotypic selection on fruit defense traits. Third, variation in the number of spines on fruits among islands is consistent with divergent phenotypic selection imposed by variation in finch community composition among islands. These results suggest that Darwin’s finches and T. cistoides are experiencing an ongoing coevolutionary arms-race, and that the strength of this coevolution varies in space and time.
Usage Notes:Seed predation of Tribulus cistoides seeds by Darwin's finches on natural populations
Mericarps were sampled from 30 T. cistoides populations across seven islands of the archipelago over three years (2015-2017). For each mericarp, we measured length (mm), width (mm), and the distance between the tips of the upper spines (upper spine size, mm) located towards the distal end of the mericarp, noted the presence or absence of lower spines, and the number of seeds removed by finches. Geographic coordinates of each population is provided in Appendix S1: Table S1.Data_1.txtVariation in fruit morphology among individual plants
Morphological measurements of Tribulus cistoides fruits from two natural populations (AB and EG) on Santa Cruz island. We sampled 15 individual plants on each site, from each of which we collected four complete (i.e., uneaten) and mature fruits (schizocarps), with each schizocarp having 4 to 5 mericarps. From each mericarp we registered length (mm), width (mm), upper spine size, presence of lower spines, and mericarp mass (mm).Data_2.txt - , Hendry, Andrew P., , , , Gotanda, Kiyoko M., , Chaves, Jaime A.et
- Dépôt source:
- Dryad
- Éditeur(s):
- Dryad
- Accès:
- Public
- URL:
- http://datadryad.org/stash/dataset/doi:10.5061/dryad.qq4715f
- Date de publication:
- 2020-01-13
- Mots-clés (en):
- Identificateur:
- https://doi.org/10.5061/dryad.qq4715f
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