DOI: 10.5061/dryad.612jm64gq
title: Declining floral color diversity shifts bee color preferences in fragmented habitats

description: Habitat fragmentation reduces floral color diversity in plant communities,
 shifting in color preferences of bee pollinators as shown by altered
 visitation frequency. We conducted a two-year survey of plant-bee
 interactions on 41 islands and the adjacent mainland habitats in a
 reservoir island system of eastern China. Reflectance spectra of the
 flower samples were measured using a portable spectrometer. Results showed
 that floral color composition was predominantly blue-green and blue, and a
 reduction in island area significantly decreased floral color diversity.
 Visitation frequencies to blue-green, ultraviolet-blue, and
 ultraviolet-green floral colors declined significantly with decreasing
 island area. Changes in floral color diversity altered bees’ color
 preferences, significantly impacting total floral visitation frequency.
 Bees’ color preference for blue-green flowers increased with island area,
 and floral resources showed no significant effect on visitation
 frequencies.
description: # Declining floral color diversity shifts bee color preferences in
 fragmented habitats Dataset DOI:
 [10.5061/dryad.612jm64gq](10.5061/dryad.612jm64gq) ## Description of the
 data and file structure We selected 41 islands (seven large islands
 (&gt;20 ha) and 34 small islands) and 16 mainland sampling sites for field
 surveys in Thousand Island Lake. We conducted biweekly surveys covering
 all islands from March 22 to July 15, 2023, and from March 26 to July 23,
 2024. For each year, we had seven replicated surveys. Each survey was
 carried out on days without rain or strong winds during two time slots:
 8:30-12:00 and 13:00-17:00. At each site, we established fixed transects
 (100-m long × 4-m wide) in edge habitats with high flowering herb richness
 and another in interior habitats extending inward from the edge. Edge
 transects were surveyed for 15 minutes, and interior transects for 10
 minutes per visit. We recorded bee visits, defined as contact with anthers
 or stigmas on flowers of herbs, shrubs, and trees within a vertical layer
 of 3.5 m above ground. We identified bee species and estimated their
 abundance, recording the visiting behavior through photographs or
 videos. We defined the visitation frequencies as the number of bees
 observed visiting flowers per unit area of each floral color. Reflectance
 spectra of the samples were measured using an Ocean Insight portable
 spectrometer (model SR-6UVV400-25; wavelength range: 180–850 nm) with
 Ocean View software. The spectrometer system consists of a
 deuterium-halogen light source (AvaLight-DHc: 200–2,500 nm), a fiber optic
 probe, and a standardized white panel for calibration. Reflectance spectra
 were recorded over the 300–700 nm wavelength range. Software parameters
 were set to automatically save measurements every 100 ms, with six
 consecutive scans collected and stored for each sample to obtain six
 technical replicates. Reflectance values from multiple points were
 averaged to generate composite spectral data for each flower.  ### Files
 and variables #### File: plant_bee_interactions_on_islands.zip
 **Description:** The dataset comprises plant-bee interaction records from
 41 islands and adjacent mainland areas in Thousand Island Lake. This
 dataset is provided as a compressed archive comprising 42 Excel files,
 each named according to its island and mainland. Every file is structured
 with the following column headers: `island`, which corresponds to the
 island number; `number`, which indicates the count of interactions;
 `plants`, which identifies the plant species code; and `bees`, which
 identifies the bee species code. #### File:
 flower_color_reflectance_spectra.xlsx **Description:** Reflectance value
 of flower color of each plant species at specific wavelengths. #####
 Variables * The first column ("wavelength") specifies light
 wavelength (nm), the header row ("PL1-PL98") denotes 98 distinct
 plant species, and the numerical values represent floral color reflectance
 measured at specific wavelengths across the spectrum. #### File:
 bee_visitation_frequency_to_each_floral_color_within_each_island.xlsx
 **Description:** The visitation frequencies of bees to each floral color
 type across the island and the adjacent mainland habitats. ##### Variables
 * The first column designates sampling locations (islands and mainland),
 the first row identifies floral color types. The color codes B, BG, G, UB,
 and UG correspond to blue, blue-green, green, ultraviolet-blue, and
 ultraviolet-green floral colors, respectively, which represent
 bee-perceptible chromatic signals. And numerical values correspond to bee
 visitation frequencies (number per unit area) for each color type. Missing
 data are represented by blank cells.