DOI: 10.5061/dryad.mcvdnck08
title: Data from: Evidence of female preference for odour of distant over local males in a bat with female dispersal

description: Geographic variation of sexual selected male traits is common in animals.
 Female choice also varies geographically and several studies found female
 preference for local males, which is assumed to lead to local adaptation
 and therefore increases fitness. As females are the non-dispersing sex in
 most mammalian taxa, this preference for local males might be explained by
 learning of male characteristics. Studies on preference of females in
 female-dispersing species are lacking so far. To find out whether such
 females would also show preferences for local males, we conducted a study
 on greater sac-winged bats (Saccopteryx bilineata), a species where
 females disperse and males stay in their natal colony. Male greater
 sac-winged bats possess a wing pouch that is filled with odoriferous
 secretion and fanned towards females during courtship display. In a
 combination of chemical analysis and behavioural preference tests, we
 analysed whether the composition of wing sac secretion varies between two
 geographically distinct populations (300 km), and whether females show a
 preference for local or distant male scent. Using gas-chromatography, we
 found significant differences in the composition of the wing-sac odours
 between the two geographic distinct populations. In addition, the
 behavioural preference experiments revealed that females of both
 populations preferred scent of geographically distant males over local
 males. The wing-sac odour might thus be used to guarantee optimal
 outbreeding when dispersing to a new colony. This is – to our knowledge –
 the first study on odour preference of females of a species with
 female-biased dispersal.
description: We collected odour samples from the males by wiping each of the
 two wing sacs with a piece of cotton of ∼5mg that had previously been
 washed with dichlormethane (DCM; 99.9%) to remove potential contaminating
 substances. We stored the samples individually in Teflon-capped glass
 vials (2 ml Rotilabo, Karlsruhe, Germany) at -20°C until further
 use. Samples were stored
 at -20°C prior analysis. All samples were prepared for analysis and
 analysed at Bielefeld University, Department of Behavioural Ecology. Prior
 to chemical extraction, we first defrosted the samples for a minimum of 60
 min under laboratory temperature (22 °C). After the samples had ambient
 temperature we added 100µl of DCM. Samples were then extracted by
 squeezing out the cotton dapper using a blunt point syringe (100 µl, ILS,
 Stützerbach, Germany). We transferred each extract into a glass vial (2
 ml, Rotilabo®, Karlsruhe, Germany) that was equipped with a 100 µl inlet
 (Rotilabo®, Karlsruhe, Germany). The extracts were concentrated by
 evaporation to approximately 5 µl before analysis. 
 These samples were analysed by gas chromatography (GC-FID,
 Shimadzu GC 2010) equipped with a VF-5ms capillary column (30 m x 0.25 mm
 ID, DF 0.25, 10 m guard column, Varian Inc., Lake Forest, California,
 USA). Therefore, one μl of each sample was injected into a deactivated
 glasswool-packed liner at an inlet temperature of 220 °C and processed in
 a split 10 mode with 20 ml/min split flow. Hydrogen was used as carrier
 gas and its flow rate was held at 1 ml/min. The GC temperature started at
 60 °C initial time of 3 min, followed by a 10°C/min rate to a final
 temperature of 280 °C, which was kept for 20 min. To compare the
 composition of wing sac chemical fingerprints, we used all substances that
 were absent in the cotton blank samples and present in at least in two
 greater sac-winged bat samples, i.e. we removed those substances that were
 found in one sample, only.  In total, we identified 282 different putative
 substances, which were found at least in two samples. Substances were
 aligned based on retention time using the R-Skript GCAlignR (Ottensmann et
 al. 2018).