Vocal coselection in rat pup ultrasonic vocalizations

Abstract

Selective breeding and natural selection that select for one trait often bring along other correlated traits via coselection. Selective breeding for an infantile trait, high or low call rates of isolation‐induced ultrasonic vocalization of rat pups, also alters functions of some brain systems and emotional behaviors throughout life. We examined the effect of breeding for call rate on acoustic parameters that are of communicative significance. Selecting for higher call rate produced calls of significantly increased amplitude and bandwidth relative to a randomly bred line. Selecting for lower rate produced calls of decreased duration. These nonmorphological, functional trait changes demonstrate enhanced communicatory potential and energy expenditure for the High line and the opposite for the Low line. This demonstration of coselection in a communicatory system suggests an underlying heritable suite of linked acoustic vocalization characteristics that in noisy environments could enhance dam–pup communication and lead to selection of emotionality traits with beneficial responses to stress.

Born to Cry: A Genetic Dissection of Infant Vocalization

“…A dystonic rat model shows a close association between an overall slower breathing rate and different vocal characteristics compared to wild-type ( Riede et al, 2015 ). Interestingly, rat pups that were selectively bred for high call rates of isolation-induced vocalization, produced calls of significantly increased amplitude but those pup with lower vocal rates also produced calls shorter in duration ( Spence et al, 2016 ), suggesting that these vocal parameters are highly interrelated. A detailed study of the relationship between lung pressure, glottal configuration and rodent USV is necessary, and future studies should include respiratory measurements in the B6 and D2 strain and their hybrids in order to understand how differences in breathing control may translate into vocal differences.…”

“…The brain is not only essential for controlling the breathing characterizes described above, but also for the ability to vocalize in response to appropriate stimuli. Selective breeding for certain traits, for example high call rates, also alters functions of brain systems and emotional behaviors throughout life ( Spence et al, 2016 ). Candidate brain areas include the cerebellum, which plays an important role in vocalization and articulation.…”

“…A low heritability usually indicates intense neutralizing selection, whereas high heritabilities are often associated with phenotypes that either do not greatly affect fitness (relaxed selection) or that are controlled by balancing selection ( Walsh and Lynch, 2018 ) that increases variability, perhaps in order to enhance kin and litter recognition ( Forstmeier et al, 2009 ; Blumstein et al, 2013 ). Hahn et al (1997) hypothesized that rates of calling has undergone more intense selection than other characters ( Hahn et al, 1997 ), however Spence et al (2016) have shown that acoustic characteristics usually do not change in isolation but are highly interrelated ( Spence et al, 2016 ). Here, we have expanded the analysis of USVs in order to comprehensively evaluate heritability of spectral, temporal, and sound amplitude characteristics.…”

Biological Functions of Rat Ultrasonic Vocalizations, Arousal Mechanisms, and Call Initiation

“…In successive days after birth, the isolation calls gradually become longer and more complex, and the sound frequency within each call has a fluctuating character across many frequencies in a fashion similar to an ambulance siren [ 34 ], and they may reach significantly deep fluctuations. This pattern of emitting vocalizations could appear by the natural vocal selection that was demonstrated in infant rats [ 35 ]. Although there are some differences in the number of emitted calls, peak frequency, and frequency modulation among male and female pups of the main laboratory strains of Wistars, Long–Evans, and Sprague Dawley rats [ 36 , 37 ], the principle of locating the calling pup remains the same.…”

Ultrasonic vocalization of pup and adult fat-tailed gerbils (Pachyuromys duprasi)

“…In the Asian house shrew Suncus murinus , five of seven call types found in pups were also found in adults [118]. In rats, creation of strains with high or low rates of isolation-induced USV evokes corresponding changes in ontogeny of acoustic parameters, suggesting that traits of USV calls are genetically predetermined [119]. In domestic mice, pups produced 10 of 11 USV syllable types recorded from adults [7].…”