Personality affects female mate choice: frogs displaying more consistent bold behaviors are choosier

Mate choice is an important cause of natural and sexual selection, and drives the evolution and elaboration of male ornaments. Yet mate choice decisions are often neither consistent nor uniform, and a range of factors have been identified to influence variation between and within individuals. A potential source of variation influencing preferences and/or choosiness is animal personality, i.e., repeatable among-individual differences in behaviors. Not only may individuals differ in average personality phenotype, but also vary in how consistently they display said personality. Distinguishing between personality and consistency is important because both aspects are potentially naturally selected traits that may yet influence how sexually selected ornaments are evaluated. Here we use a predator evasion assay to test whether there is variation in boldness among female gray treefrogs (Hyla versicolor), and then examine whether personality traits (spectrum of shy to bold) are correlated with choosiness for longer duration calls. We document substantial and repeatable between-individual variation in boldness, suggesting the presence of animal personality. Results also reveal that the consistency with which females expressed boldness is independent from average personality phenotype and that it is correlated with choosiness: more consistently bold females were choosier. 

Methods
Uploaded here are two CSV files associated with different stages of the data collection and analysis; (1) assessment of personality via boldness and (2) relationship between boldness and choosiness.

(1) PERSONALITY FILE

Personality Assay – The personality experiment measured boldness using severity of escape responses to an approaching novel predator in Eastern Gray Treefrogs (Hyla versicolor). We confronted each frog with a slowly approaching artificial predator that recreated the shadow effect of a looming predator – a black square with eyespots affixed to the front of a wooden, wheeled children's "Pull Along Duck" toy. To begin, the frog was placed on a short PVC perch elevated and centered within a one-meter diameter circular arena. As the predator approached, we scored the following frog behaviors in a binary fashion: flinching, turning, hiding, and jumping. We considered behaviors that happened both before and the moment when the predator collided with the perch, although severity of responses before/after were scored differently. If the frog exhibited no jumping response before the predator made contact, the trial was repeated again for a maximum of three attempts to assess the breadth of behavioral responses.

Personality Data Translation -- For each replicate, the binary behavior scores were assigned values (0.1 to 1) representative of severity of response and used to calculate escape score as the final measure of boldness. Values assigned: flinch at contact = 0.1, flinch before contact = 0.2, turn at contact = 0.3, turn before contact = 0.4, jump/hide at contact = 0.8, and jump/hide before contact = 1. Escape score was calculated from the sum of the behaviors exhibited by each frog, adjusted by number of attempts per replicate. Then, sums were divided by the maximum possible value (1.6) for a more intuitive measure, bolder individuals were associated with higher escape scores. 

Personality Dataset -- The data sheet provides (A) female ID, (B) replicate number, (C) number of attempts, (D-J) scored behaviors, (K-L) conversion into escape scores, and (M) final escape score. Columns O and P show the score value of each behavior. 

(2) CHOOSINESS-PERSONALITY FILE

Choosiness Assay -- We were most interested in comparing personality to mate choice. We used one measure of mate choice, choosiness, which indicates the amount of energy a female is willing to invest for the most attractive mate. We used acoustic dual-speaker playback trials with Eastern Gray Treefrogs to present each female with artificial male call stimuli. In each choosiness trial, two stimuli were presented to the female (6 pulses and 18 pulses) played at different amplitudes. By manipulating amplitude, we change the perceived distance from the call, so a quieter call=further away. The choosiness data here indicates the maximum amplitude difference between stimuli (the quietest dB in which the attractive stimulus was chosen).

Choosiness-Personality Dataset -- As we had previously confirmed that inter-individual differences were maintained across replicates (personality via escape score), we were able to compare the morphology and choosiness data to the mean escape score across replicates and the associated CV. This data sheet provides (A) female ID, (B) body size measured in mm (snout-vent-length; SVL), (C) body condition, the regression between mass (g) and SVL (mm), (D) choosiness as maximum dB in which the female chose the attractive call, (E) mean escape score across replicates, and (F) CV of escape scores. The mean escape score indicates personality phenotype and CV indicates individual consistency across replicates.