Ontogeny of long-range vocalizations in a Neotropical fossorial rodent: the Anillaco Tuco-Tuco (Ctenomyssp.)

Abstract

Tuco-tucos (Ctenomys spp.) are subterranean rodents that produce territorial, high intensity long-range vocalizations (LRVs) of broadband and low frequency that are essential for long-distance communication between individuals in different tunnel systems. Despite their importance, the development of LRVs remains poorly understood. In adult Anillaco Tuco-Tucos (Ctenomys sp.) the LRV is composed by two types of syllables (series and individual notes) that are repeated a variable number of times. We studied the development of the LRVs in eight juveniles of the Anillaco Tuco-Tuco ranging from 14–28 to 104–118 days after birth. We (1) tested whether the syllables followed any of three alternative developmental modes (retention of juvenile vocalizations, modification of juvenile precursors or de novo appearance in adults), (2) evaluated the development of structural and acoustic features of syllables, and (3) tested the prediction that juveniles should produce a greater proportion of atypical series in precursors of the LRV than adults, due to lack maturation and/or precise coupling of neuromuscular and anatomical structures. The LRV of the Anillaco Tuco-Tuco exhibited a mixed developmental mode: while series developed from juvenile precursors whose acoustic features gradually approached those of adults, individual notes appeared later in the ontogeny and de novo with acoustic features indistinguishable from those of adults. The number of series per vocalization increased through development and varied from one to 25 in juvenile males and from one to six in juvenile females. The structure of the most common series type (triad) did not exhibit ontogenetic changes and was present as such at the onset of the emission of vocalizations. On the contrary, acoustic features of juvenile triad notes changed with age in both sexes (duration 90% increased through development, while bandwidth 90% and peak frequency decreased). Furthermore, juveniles emitted a higher proportion of atypical series than adults (7.4% vs. 0.3%), as expected in the development of any complex behavior that requires practice to be mastered. The maturation of the LRV occurred well before the sexual maturation, presumably due to the protracted time needed to acquire or build a burrow system long before mating is possible. We propose that protracted vocal development is another component in the slow developmental strategy of Ctenomys and subterranean rodents in general.

Function‐related Drivers of Skull Morphometric Variation and Sexual Size Dimorphism in a Subterranean Rodent, Plateau Zokor (Eospalax baileyi)

“…Measurements of tympanic bulla also showed MBSSD. Zokors have weak vision (Kott, Sumbera, & Nemec, ) because of the underground living conditions; signals of predators and competitors are conveyed through low‐frequency acoustic stimuli (Amaya, Areta, Valentinuzzi, & Zufiaurre, ; Hegab, Kong, Yang, Mohamaden, & Wei, ). Plateau zokors are highly territorial, solitary, and aggressive toward each other, irrespective of sex (Zhang et al., ); therefore, males are responsible to guard a larger home range, which might result in the evolution of a more efficient auditory system to receive low‐frequency auditory signals (Squarcia et al., ).…”

Description of the sound diversity of two species of tuco-tucos (Ctenomys torquatusandCtenomys lami) in natural environment

“…Ctenomys talarum [20,29], the Pearson's tuco-tuco: Ctenomys pearsoni [19,26,30,31] and Anillaco tuco-tuco: Ctenomys sp [25,32]. In addition, Francescoli & Quirici [33] showed two possible vocal patterns that could be shared with other species of Ctenomys.…”

Review of three neglected species of Ctenomys (Rodentia: Ctenomyidae) from Argentina

“…In addition, its distribution has been recently extended to include populations from the localities of Anillaco and Pampa de la Viuda, in La Rioja province, Argentina (Tammone et al 2022). The populations from Anillaco (then treated as C. famosus) have been previously the subject of detailed studies of circadian rhythms, vocalization, and ecology, although they have been erroneously identified under the names of other species (see Valentinuzzi et al 2009;Fracchia et al 2011;Tomotani et al 2012Tomotani et al , 2016Tachinardi et al 2014;Amaya et al 2016Amaya et al , 2021Amaya and Areta 2018;Jannetti et al 2019).…”