Data from: Pollinator-mediated isolation promotes coexistence of closely related food-deceptive orchids

Identifying the factors that contribute to reproductive isolation among closely-related species is key for understanding the diversification of lineages. In this study, we investigate the strength of premating and postmating reproductive isolation barriers between Disa ferruginea and Disa gladioliflora, a pair of closely-related species, often found co-flowering in sympatry. Both species are non-rewarding and rely on mimicry of different rewarding model flowers for attraction of pollinators. We constructed abiotic niche models for different forms of each taxon to measure ecogeographic isolation. Using experimental arrays in sympatry, we recorded pollinator transitions to measure ethological isolation. We performed hand pollinations to measure postpollination isolation. We found strong, but not complete, premating isolation associated with abiotic niches and absolute ethological isolation based on pollinator preferences in sympatry. Pollinator preferences among the orchids could be explained largely by flower colour (orange in D. ferruginea and pink in D. gladioliflora) which matches that of the pollinator food plants. Post-mating barriers were weak as the species were found to be inter-fertile. Coexistence in the orchid species pair is due mainly to ethological reproductive isolation arising from flower colour differences resulting from mimicry of different rewarding plants. These results highlight the importance of signalling traits for ethological isolation of closely-related species with specialized pollination systems. # Pollinator-mediated isolation promotes coexistence of closely related food-deceptive orchids [doi.org](doi.org) ## Description of the data and file structure This data was collected in the field at Boosmansbos Wilderness Area in the Western Cape of South Africa. The two experiments involved a preference experiment using floral arrays of the two closely related orchids with pollinators, this was used to confirm pollinator-mediated isolation. We also conducted a hand pollination experiment between the two orchid species to determine postpollination isolation. Furthermore, floral measurements were taken to compare floral traits between mimics and models. We also extracted environmental variables from point localities using QGIS to determine the abiotic niche of the two orchids. ### Files and variables #### File: abiotic\_variables.csv **Description:** Abiotic variables used to generate the PCA associated with the abiotic niche the two orchids occupy. N/A refers to missing values in the dataset. ##### Variables * species: Disa ferruginea & Disa gladioliflora * Geology: Values for Geology * Max_temp_warmest_month1 (C*100): Values for Maximum temperature in the warmest month * Min_temp_cold_month1 (C*100): Values forMinimum temperature in the coldest month * Precip_dryest_quart: Values for Precipitation in the driest quarter * Precip_seasonality1: Values for Precipitation seasonality * Precip_wettest_quarter1:Values for Precipitation in the wettest quarter * Precipitation1:Values for Mean precipitation * Temp_Season1 (C):Values for Temperature seasonality * annual mean tremperature1 (C*100): Values for Annual mean temperature #### File: Disa\_ferruginea\_mimic\_model\_comp.csv **Description:** Trait values used to generate boxplots and associated analysis ##### Variables * Species: Disa gladioliflora * Plant Height (mm): Values for measurements taken from the ground to the top of inflorescence * display_size (mm) Values for the size of the display * inflorescence width (mm) Values fort the width of the inflorescence between the two furthest points * Spur length (mm): Values for length of the spurs associated with mechanical fit with insect proboscis length #### File: Disa\_gladioliflora\_mimic\_model\_comp.csv **Description:**  Trait values used to generate boxplots and associated analysis **Variables** * Species: Disa ferruguinea * Plant Height (mm) Values for measurements taken from the ground to the top of inflorescence * display_size (mm): Values for the size of the display * inflorescence width (mm): Values for the width of the inflorescence between the two furthest points * Spur length (mm): Values for length of the spurs associated with mechanical fit with insect proboscis length #### File: disa\_preferences.csv **Description:** Values from experimental array experiment used to determine floral isolation  ##### Variables * date: The date of a particular observation * obs_day: number of day in the field * pair_number: pair number of array set up in experiment * visitor: species of insect visiting * individual: Identity of individual insect visiting floral arrays * preference: taxon visited * First_preference: Binary values in favour of Disa gladioliflora * probes: Number of probes made by insect per visit #### File: Postzygotic\_isolation.csv **Description:** Values associated with handpollinations used to determine postpollination isolation ##### Variables * Recipient: Taxon on which pollen has been placed on the stigma * Treatment: Experimental treatment being either conspecific or heterospecific * fruit_set: presence or absence of fruit set (1: yes; 0:no) * viable_seeds: seeds containing an embryo in the seedcoat * Total_seeds: Total seeds from which we determined the proportion viable embryos #### File: Disa\_ECOGEO\_OCT\_24.csv **Description:** The dataset used to calculate ecogeographic isolation based on overlap of predicted niches with the ETSS threshold provided by MAXENT. ##### Variables * id: grid number from shape file * Disa_glad_2mean: Values extracted from QGIS using Zonal statistics on the .asc file associated with the maxent predicted model for Disa gladioliflora * Disa_ferr_avg2mean:Values extracted from QGIS using Zonal statistics on the .asc file associated with the maxent predicted model for Disa ferruginea #### File: Disa\_colour\_spectra.csv **Description:** Colour spectra from the flowers of mimics and models ##### Variables * Wavelength: wavelength in nanometers * Ind1.G: spectra for Disa gladioliflora Individual 1 * Ind1.F: spectra for Disa ferruginea Individual 1 * Ind1.T: spectra for Tritoniopsis ramosa Individual 1 * Ind1.K: spectra for Kniphofia uvaria Individual 1 * Ind2.G: same as above but for individual 2 * Ind2.F: same as above but for individual 2 * Ind2.T: same as above but for individual 2 * Ind2.K: same as above but for individual 2 * Ind3.G: individual 3 * Ind3.F: individual 3 * Ind3.T: individual 3 * Ind3.K: individual 3 * Ind4.G: individual 4 * Ind4.F: individual 4 * Ind4.T: individual 4 * Ind4.K: individual 4 * Ind5.G: individual 5 * Ind5.F: individual 5 * Ind5.T: individual 5 * Ind5.K: individual 5