Abstract
BackgroundUltrasonic vocalizations (USVs) emitted by muroid rodents, including laboratory mice and rats, are used as phenotypic markers in behavioral assays and biomedical research. Interpretation of these USVs depends on understanding the significance of USV production by rodents in the wild. However, there has never been a study of muroid rodent ultrasound function in the wild and comparisons of USVs produced by wild and laboratory rodents are lacking to date. Here, we report the first comparison of wild and captive rodent USVs recorded from the same species, Peromyscus californicus.Methodology and Principal FindingsWe used standard ultrasound recording techniques to measure USVs from California mice in the laboratory (Peromyscus Genetic Stock Center, SC, USA) and the wild (Hastings Natural History Reserve, CA, USA). To determine which California mouse in the wild was vocalizing, we used a remote sensing method that used a 12-microphone acoustic localization array coupled with automated radio telemetry of all resident Peromyscus californicus in the area of the acoustic localization array. California mice in the laboratory and the wild produced the same types of USV motifs. However, wild California mice produced USVs that were 2–8 kHz higher in median frequency and significantly more variable in frequency than laboratory California mice.SignificanceThe similarity in overall form of USVs from wild and laboratory California mice demonstrates that production of USVs by captive Peromyscus is not an artifact of captivity. Our study validates the widespread use of USVs in laboratory rodents as behavioral indicators but highlights that particular characteristics of laboratory USVs may not reflect natural conditions.
Highlights
There has been extensive laboratory research on rodent Ultrasonic vocalizations (USVs) within the superfamily Muroidea [1], especially in laboratory mice (Mus spp) and rats (Rattus spp), which serve as mammalian nonhuman models in most areas of biological research
With the exception of the second syllable of 2-syllable vocalizations (2SVs), there was no difference in bandwidth of syllables between wild and laboratory USVs with bandwidth ranging from a median of 2.40 to 4.90 kHz regardless of syllable number, motif type, or whether mice were from the wild or the laboratory (Table 1, Table 2, Table 3)
Syllables recorded from wild California mice were consistently more modulated, both overall and internally, compared with syllables recorded from the wild and this higher modulation was significant in 1-syllable vocalizations (1SVs) and the first syllable of 3-syllable vocalizations (3SVs) (Table 1, Table 2, Table 3)
Summary
There has been extensive laboratory research on rodent USVs within the superfamily Muroidea [1], especially in laboratory mice (Mus spp) and rats (Rattus spp), which serve as mammalian nonhuman models in most areas of biological research. Mus and Rattus predictably produce USVs in the laboratory and their USV patterns are used as a phenotypic marker in behavioral assays [2]. In adult Mus, USVs are associated with male-female [5] and female-female social interactions [4]. Ultrasonic vocalizations (USVs) emitted by muroid rodents, including laboratory mice and rats, are used as phenotypic markers in behavioral assays and biomedical research. Interpretation of these USVs depends on understanding the significance of USV production by rodents in the wild. There has never been a study of muroid rodent ultrasound function in the wild and comparisons of USVs produced by wild and laboratory rodents are lacking to date. We report the first comparison of wild and captive rodent USVs recorded from the same species, Peromyscus californicus
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