DOI: 10.5061/dryad.tmpg4f4tw
title: Data from: The landscape genetic signature of pollination by trapliners: evidence from the tropical herb, Heliconia tortuosa

description: Animal-mediated pollination is essential for the maintenance of plant
 reproduction, especially in tropical ecosystems, where pollination
 networks have been thought to have highly generalized structures. However,
 accumulating evidence suggests that not all floral visitors provide
 equally effective pollination services, potentially reducing the number of
 realized pollinators and increasing the cryptic specialization of
 pollination networks. Thus, there is a need to understand how different
 functional groups of pollinators influence pollination success. Here we
 examined whether patterns of contemporary pollen-mediated gene flow in
 Heliconia tortuosa are consistent with the foraging strategy of its
 territorial or traplining hummingbird pollinators. Territorial
 hummingbirds defend clumps of flowers and are expected to transfer pollen
 locally. In contrast, traplining hummingbirds forage across longer
 distances, thereby increasing pollen flow among forest fragments, and are
 thought to repeatedly visit particular plants. If trapliners indeed visit
 the same plants repeatedly along their regular routes, this could lead to
 a situation where neighboring plants sample genetically distinct pollen
 pools. To test this hypothesis, we genotyped 720 seeds and 71 mother
 plants from 18 forest fragments at 11 microsatellite loci. We performed
 TwoGener analysis to test pollen pool differentiation within sites (among
 neighboring plants within the same forest fragment: ΦSC) and between sites
 (among forest fragments: ΦCT). We found strong, statistically significant
 pollen pool differentiation among neighboring mother plants (ΦSC =
 0.0506), and weaker, statistically significant differentiation among sites
 (ΦCT = 0.0285). We interpret this pattern of hierarchical pollen pool
 differentiation as the landscape genetic signature of the foraging
 strategy of traplining hummingbirds, where repeatable, long-distance, and
 high-fidelity routes transfer pollen among particular plants. Although H.
 tortuosa is also visited by territorial hummingbirds, our results suggest
 that these pollinators do not contribute substantially to successful
 pollination, highlighting differences in realized pollination efficiency.
 This cryptic reduction in the number of realized pollinators potentially
 increases the vulnerability of pollination success to the decline of
 populations of traplining hummingbirds, which have been shown to be
 sensitive to forest fragmentation. We conclude that maintaining habitat
 connectivity to sustain the foraging routes of trapliners may be essential
 for the maintenance of pollen-mediated gene flow in human-modified
 landscapes.
description: The study was conducted in the human-modified landscape (~ 31,000
 ha) surrounding the Organization for Tropical Studies Las Cruces
 Biological Station in southern Costa Rica (8º47N, 82º57W). We used a
 stratified-random sampling design to select 20 focal forest fragments that
 represented a gradient of forest amount within a 1-km radius and a
 gradient of fragment size. Within each focal fragment, we selected
 <i>H. tortuosa </i>plants at a random location (‘site’)
 sampled within 500 m of an access point. Starting from this sampling
 location, we marked the first five plants with inflorescences (‘mothers’)
 and sampled leaf tissue. We randomly selected two bracts on a single
 inflorescence of each mother and collected all fruits. Samples were
 amplified at 11 microsatellite loci in three multiplex
 reactions. We tested for significant pollen pool
 differentiation among sites and among mothers nested within sites by
 performing a hierarchical analysis of molecular variance (AMOVA) based on
 pollen haplotypes (TwoGener). We fitted several hierarchical AMOVA models
 where we tested for significant pollen pool differentiation among sites
 and among mothers nested within sites (<i>i.e., </i>pairwise
 genetic distance ~ site / mother). Statistics of genetic differentiation
 (<i>Φ</i>) were estimated for each level by partitioning the
 total observed genetic variation in allele frequencies into within- and
 among-level variance components. These <i>Φ</i>-statistics are
 analogous to <i>F</i>-statistics<sub> </sub>and
 provide estimates of the genetic differentiation of pollen pools sampled
 among sites (<i>Φ<sub>CT</sub></i>) and among
 individual mothers within sites
 (<i>Φ<sub>SC</sub></i>). To
 evaluate limitations associated with our sampling design, we simulated
 pollen pool differentiation among sites and among mothers within sites to
 assess the type I error rates and the statistical power of the
 hierarchical AMOVA models we fitted. Simulations were completed with
 different levels of genetic diversity and pollen pool
 differentiation.
description: <strong>TwoGener</strong> All
 files necessary to complete the TwoGener analysis include the TwoGener_
 prefix. Files include: 1.
 TwoGener_README.txt. 2. TwoGener_Raw_Data.csv
 3. TwoGener_AMOVA.rmd
 <strong>Paternity</strong> All
 files for the paternity analysis implemented in COLONY include the
 Paternity_ prefix. Files include: 1.
 Paternity_README.txt 2.
 Paternity_OffspringGenotypes.csv 3.
 Paternity_MothersGenotypes.csv 4.
 Paternity_MaternalSibs.csv 5.
 Paternity_MarkerErroRate.csv 6.
 Paternity_ExclusionMaternity.csv 7.
 Paternity_ExclusionMaternalSibs.csv 8.
 Paternity_Selfed_Seeds.csv 9.
 Paternity_Project_Information.txt
 <strong>Simulations</strong> The R
 code for the simulations of pollen pool differentiation is
 provided. 1. Simulations.rmd
 <strong>Mating System</strong> All
 files for the estimation of outcrossing rates in MLTR include the
 MatingSystem_ prefix. Files include: 1.
 MatingSystem_README.txt 2.
 MatingSystem_Seeds.txt 3.
 MatingSystem_Mothers_Seeds.txt <strong>Loci
 Information</strong> Basic information for the 11
 microsatellite loci were estimated in CERVUS and are given in:
 1. Loci_Information.txt 2.
 Loci_Information_Genotypes.txt