Characterizing sex and species differences in muscle physiology can contribute to a better understanding of proximate mechanisms underlying behavioral evolution. In Xenopus, the laryngeal muscle’s ability to contract rapidly and its electromyogram potentiation allows males to produce calls that are more rapid and intensity-modulated than female calls. Prior comparative studies have shown that some species lacking typical male features of vocalizations sometimes show reduced sex differences in underlying laryngeal physiology. To further understand the evolution of sexually differentiated laryngeal muscle physiology and its role in generating behavior, we investigated sex differences in the laryngeal physiology of X. muelleri, a species in which male and female calls are similar in rapidity but different with respect to intensity modulation. We delivered ethologically relevant stimulus patterns to ex vivo X. muelleri larynges to investigate their ability to produce various call patterns, and we also delivered stimuli over a broader range of intervals to assess sex differences in muscle tension and electromyogram potentiation. We found a small but statistically significant sex difference in laryngeal electromyogram potentiation that varied depending on the number of stimuli. We also found a small interaction between sex and stimulus interval on muscle tension over an ethologically relevant range of stimulus intervals; male larynges were able to produce similar tensions to female larynges at slightly smaller (11–12 ms) inter-stimulus intervals. These findings are consistent with behavioral observations and present a previously undescribed intermediate sex difference in Xenopus laryngeal muscle physiology.

All csv files including acoustic data (Pattern_IM, Pattern_Interval, Pulse_Numbers, patternAspectrogram, and patternBspectrogram) come from audio recordings from male X. muelleri only. All other files include data compiled from both males and females. Acoustic data was obtained using Audacity (v. 2.3.0, audacityteam.org) computer software and electrophysiology data was obtained using LabChart (v. 8.0.10, ADInstruments) computer software. 

This South_Xmuelleri_Readme.txt file was generated on 2021-02-22 by Kelly South

2. Author Information
    A. Principal Investigator Contact Information
        Name: Dr. Elizabeth Leininger
        Institution: New College of Florida
        Address: 
        Email: eleininger@ncf.edu

    B. Associate or Co-investigator Contact Information
        Name: Kelly South
        Institution: New College of Florida
        Address: 
        Email: kelly.south15@ncf.edu

3. Date of data collection: 2018/01/15-2019/05/17

4. Geographic location of data collection: New College of Florida, Sarasota, FL, 34243 USA

5. Information about funding sources that supported the collection of the data: Internal funding from New College of Florida and the New College Women's Giving Circle

SHARING/ACCESS INFORMATION

1. Licenses/restrictions placed on the data: NA

2. Links to publications that cite or use the data: NA

3. Links to other publicly accessible locations of the data: NA

4. Links/relationships to ancillary data sets: NA

5. Was data derived from another source? No

6. Recommended citation for this dataset: 

DATA & FILE OVERVIEW

1. File List: 
Male_Female_Weights.csv            Body mass (g) and larynx mass (g) for all tested individuals
ApproachPI.csv                Average electromyogram potentiation index for approach call trains
patternAspectrogram.csv            Spectral information for recorded pattern A calls
patternBspectrogram.csv            Spectral information for recorded pattern B calls
Pulse_Numbers.csv            Distribution of pulse numbers per call
Pattern_IM.csv                Average intensity modulation for each call pattern
Pattern_Interval.csv            Average inter-call interval and inter-pulse interval for each call pattern
PTTdata.csv                Percent transient tension for tested inter-stimulus intervals and the order of stimulation (sequence)
EMGdata.csv                Potentiation index for tested inter-stimulus intervals and the order of stimulation (sequence)

2. Relationship between files, if important: 

3. Additional related data collected that was not included in the current data package: 

4. Are there multiple versions of the dataset? No

METHODOLOGICAL INFORMATION

1. Description of methods used for collection/generation of data: Data collection and analysis based on experimental protocols from Leininger et al, (2015) and Tobias and Kelley, (1987)
Leininger, E. C., Kitayama, K. and Kelley, D. B. (2015). Species-specific loss of sexual dimorphism in vocal effectors accompanies vocal simplification in African clawed frogs (Xenopus). J. Exp. Biol. 218, 849–857.
Tobias, M. L. and Kelley, D. B. (1987). Vocalizations by a sexually dimorphic isolated larynx: peripheral constraints on behavioral expression. J. Neurosci. 7, 3191–3197.

2. Instrument- or software-specific information needed to interpret the data: NA

3. Standards and calibration information, if appropriate: NA

4. Environmental/experimental conditions: Audio recorded from frogs in 22-23 degrees C 4% Holtfreter's solution. Electrophysiology experiments conducted in chilled (10 degrees C) dextrose-supplemented Ringer's solution

5. Describe any quality-assurance procedures performed on the data: NA

6. People involved with sample collection, processing, analysis and/or submission: Kelly South

DATA-SPECIFIC INFORMATION FOR: ApproachPI.csv

1. Number of variables: 2

2. Number of cases/rows: 12

3. Variable List: 
Sex
PI (potentiation index - analysis of the increase or decrease of strength of electrical impulses delivered, measured by dividing the amplitude difference between the maximum electromyogram and the first electromyogram (B-A) by the maximum value of the first electromyogram (A); (B-A)/A)

4. Missing data codes: NA

5. Specialized formats or other abbreviations used: NA

DATA-SPECIFIC INFORMATION FOR: EMGdata.csv

1. Number of variables: 6

2. Number of cases/rows: 356

3. Variable List: 
Frog
Sex
ISI (inter-stimulus interval - amount of time between two stimulations within an electrophysiological experiment - measured in milliseconds)
Burst (first stimulation denoted as 1, average of subsequent stimulations denoted as 2 - separated due to significant differences in response to electrical stimulation)
PI (potentiation index)
Sequence (randomized order of ISI delivered to each individual)

4. Missing data codes: NA

5. Specialized formats or other abbreviations used: NA

DATA-SPECIFIC INFORMATION FOR: Male_Female_Weights.csv

1. Number of variables: 3

2. Number of cases/rows: 16

3. Variable List: 
Sex
Body (body mass measured in grams)
Larynx (larynx mass measured in grams)

4. Missing data codes: NA

5. Specialized formats or other abbreviations used: NA

DATA-SPECIFIC INFORMATION FOR: Pattern_IM.csv

1. Number of variables: 3

2. Number of cases/rows: 6

3. Variable List: 
Frog
Measure (Intensity modulation (IM)- Change in amplitude from first sound pulse (A) to highest intensity sound pulse (B) in a single call, measured by dividing the difference in maximum amplitude of the highest intensity sound pulse and first sound pulse by the maximum amplitude of the first sound pulse; (B-A)/A)
Pattern (vocal pattern recorded)

4. Missing data codes: NA

5. Specialized formats or other abbreviations used: NA

DATA-SPECIFIC INFORMATION FOR: Pattern_Interval.csv

1. Number of variables: 4

2. Number of cases/rows: 12

3. Variable List: 
Frog
Interval (Inter-call interval (ICI)- Amount of time between the first sound pulse of a call and the first sound pulse of the following call, and Inter-pulse interval (IPI) - Amount of time between sound pulses in a single call)
Measurement (time difference measured in milliseconds)
Pattern (vocal pattern associated with measurements)

4. Missing data codes: NA

5. Specialized formats or other abbreviations used: NA

DATA-SPECIFIC INFORMATION FOR: patternAspectrogram.csv and patternBspectrogram.csv

1. Number of variables: 5

2. Number of cases/rows: 771

3. Variable List: 
Frog
Hz (Raw frequency from audio recordings)
before (Background frequency)
Frequency (Normalized frequency)
Power (Relative amplitude of the frequency)

4. Missing data codes: NA

5. Specialized formats or other abbreviations used: NA

DATA-SPECIFIC INFORMATION FOR: PTTdata.csv

1. Number of variables: 5

2. Number of cases/rows: 178

3. Variable List: 
Frog
Sex
ISI (inter-stimulus interval - amount of time between two stimulations within an electrophysiological experiment - measured in milliseconds)
PTT (percent transient tension - analysis of the amount of tension present in the laryngeal muscle tendon for a given IPI, measured by dividing the difference between the first maximum peak tension (a) and the minimum trough tension (t) by the difference between the first maximum peak tension (a) and the baseline (bl); [(a-t)/(a-bl)]*100%)
Sequence (randomized order of ISI delivered to each individual)

4. Missing data codes: NA

5. Specialized formats or other abbreviations used: NA

DATA-SPECIFIC INFORMATION FOR: Pulse_Numbers.csv

1. Number of variables: 3

2. Number of cases/rows: 13

3. Variable List: 
PulseNumber (number of pulses found in a single call throughout audio recordings)
Total (total number of calls produced in audio recordings with that pulse number)
Pattern (vocal pattern assigned to the pulse number)

4. Missing data codes: NA

5. Specialized formats or other abbreviations used: NA