DOI: 10.5061/dryad.djh9w0w2v
title: Data from: Evolved differences in thermal plasticity of mosquitofish mating behavior are unrelated to source temperature

description: Phenotypic plasticity in response to temperature is expected to play a key
 role in how organisms cope with climate change. Evolved differences in
 plastic responses are often linked to historical differences in average
 temperatures, yet we know little about how behavioral plasticity is
 affected by prevailing thermal environments. In this study, we used a
 common-garden design to test whether historical differences in average
 temperatures caused evolutionary divergence in the plasticity of mating
 behavior of Western mosquitofish (Gambusia affinis) inhabiting geothermal
 springs with average source temperatures spanning from 18.8 to 33.3 C. We
 found population differences in the thermal plasticity of courtship
 displays, copulation attempts, copulations, and mating efficiency, but
 these differences could not be explained by average source temperatures.
 We also tested for differences in thermal optima and maximum performance
 in mating behavior among populations. We found that only the maximum
 number of displays differed among populations, although these differences
 were also unrelated to source temperature. While temperature may have
 predictable evolutionary consequences for some thermally sensitive traits,
 our findings are inconsistent with theoretical predictions of evolutionary
 responses to divergent average temperatures, highlighting the need for
 greater synergy between empirical and theoretical work to understand
 thermal adaptation.
description: These data were collected to investigate the effect of
 differences in average source population temperature on the evolution of
 behavioral plasticity in mating behavior in Western mosquitofish.
 Mosquitofish from 5 geothermal springs in Bishop, CA with source
 temperatures ranging from 18.9 to 33.3 C were collected and reared for two
 generations in a common thermal environment. Mating behavior of each F2
 male was observed at 5 ecologically relevant ambient temperatures (15, 20,
 26, 32, and 37 ºC) that encompassed the thermal gradient of source
 populations. The order of observation temperatures was randomized for
 individual males, although all males were first observed at intermediate
 temperatures (20, 26, 32) due to possible mortality at extreme
 temperatures (Otto 1973; Wilson 2005). Males were assayed with two
 standardized female fish from pond separate from the focal populations.
 Behavioral assays occurred in blue-felt-lined observation chambers (40 x
 21 x 12 cm deep). A camera (Olympus Stylus TG-4, Bethlehem, PA) was placed
 on a shelf above each tank to record behavior, with two 18 W lights
 affixed beneath the shelf to illuminate the field of view. 20-minute
 behavioral interactions were recorded after a 20 minute acclimation
 period. After each male's first assay, males were removed from the
 tank and photographed. Video recordings of mosquitofish
 interactions were analyzed using CowLog 3.0 behavioral coding software
 (Hänninen and Pastell 2009). Courtship displays occurred when males arched
 their body into an sigmoid-shape characteristic of poecilid courtship
 behavior (Bisazza 1993). Copulation attempts were counted when a male
 approached a female from behind and oriented beneath the female caudal
 peduncle, a position required for copulation in livebearing fish (Bisazza
 et al. 2001). Copulations occurred after a subset of attempts and were
 identified by the rapid twisting motion that accompanied the male removal
 of the gonopodium from the female gonoduct (Wilson 2005). Video observers
 were trained to identify behaviors on a standardized set of videos before
 collecting data to ensure consistency among observations. Each video
 observer was blind to treatment and source population identity when
 identifying and counting behaviors. 
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