Abstract Detail

Ecology

Hendrickson, Elizabeth [1], Thompson, Pamela [2], Cruzan, Mitchell [2].

Density dependent pollination and germination in the patchy vernal pool species Lasthenia californica.

Premise of Research: The response of animal pollinators to visual characteristics of plants is crucial to understanding how plant-pollinator interactions contribute to plant reproductive processes. For plant species that aggregate in patches, the spatial distribution and density of flowering plants in and around patches may affect pollinator visitation to a greater degree than characteristics of individual flowers. We examine how patch characteristics of the self-incompatible, vernal pool species Lasthenia californica (California goldfields) impact pollinator visitation using pollen load size and pollen germination rates to infer visitation patterns.
Methodology: Flower density and the size and distribution of patches were estimated from aerial images captured during drone surveys of an upland prairie ecosystem in Southern Oregon. Pollen load sizes and number of germinated grains were quantified using Alexander's Stain. We assessed the effects of flower density on pollen deposition and number of germinated grains for increasing neighborhood areas using multiple regression models.
Pivotal Results: We found that pollen deposition on stigmas decreased with flower density within a 3 to 20 meter radius neighborhood area. Pollen germination frequency increased with the density of flowers within an individual patch, but decreased with total flower density within a 0.5 to 1 meter radius around the patch.
Conclusions: Our results imply that increasing flower density can have negative consequences for pollination services, which could result in reduced seed set when pollinators are scarce. Although pollen deposition appears to increase in dense patches, as neighborhood density around the focal patch increases, pollen deposition rates decline, which indicates a lower pollinator visitation rate. When neighboring flower patch density is higher, pollinators probably fly shorter distances, and consequently deposit higher proportions of incompatible pollen on stigmas. Pollen deposition and germination patterns demonstrates patch and neighborhood size and density dependent effects on plant reproductive success.

1 - Portland State University, Biology, 1719 SW 10th Avenue, SRTC Rm 246, Portland, OR, 97201, United States
2 - Portland State University, Biology, 1719 SW 10th Avenue, SRTC Rm 246, Portland, OR, 97201, USA

Keywords:
flower color
Pollinator preference
Pollinator attraction
Pollen deposition
Pollinator visitation
Self-incompatibility
Patch size.

Presentation Type: Poster
Session: P, Ecology
Location: Grand Ballroom - Exhibit Hall/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 5:30 PM This poster will be presented at 6:15 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PEC030
Abstract ID:1035
Candidate for Awards:Ecological Section Best Graduate Student Poster