Gestation, maternal behaviour, growth and development in the subterranean caviomorph rodent Ctenomys mendocinus (Rodentia, Hystricognathi, Ctenomyidae)

Abstract

Th e fi rst information on the gestation period, maternal behaviour, neonatal development and growth of the subterranean caviomorph rodent Ctenomys mendocinus Philippi, 1869, is reported herein. My hypothesis was that, despite its belonging to a typically precocial suborder, the life history traits of C. mendocinus would favour its altricial condition. Th e off spring of C. mendocinus were categorized as altricial by using two diff erent classifi cation systems. Th is condition was also refl ected in maternal care. Females built large nests (2000 cm 3 ) where, after a long gestation period (95.9 days), they gave birth to litters of blind pups, half-naked, with external ear meatus open and good physical coordination. Th e mothers suckled the off spring in long bouts (19.9 min), retrieved their pups, and these showed no tactics to reduce the suckling bout. Overall, evidence was consistent with the hypothesis analyzed, although particularities found, e.g. some precocial traits, suggest the existence in C. mendocinus of a trade-off between the constraints and advantages related to its subterranean way of life and the phylogenetic inertia typical of caviomorphs.

Reproduction in the East African root rat (Tachyoryctes splendens; Rodentia: Spalacidae) from Tanzania: the importance of rainfall

“…Because precipitation is a major influence for the re-sprouting, regeneration and an overall increase in plants succession and subsequently increased vegetation cover (Bennie, 1991;Barber, 1995;Pregitzer & King, 2005), the numbers of pup births in T. splendens over the periods of rainfall might be an ultimate factor. This observation is parallel to reports documented for bathyergids, geomyids, ctenomyids, Middle East spalacids and other arboreal small mammals (Vaughan, 1962;Andersen, 1978;Bronson, 1985;Lovegrove & Jarvis, 1986;Ims, 1990;Bennett et al, 1991;Malizia & Busch, 1997;Bennett & Faulkes, 2000;Herbst et al, 2004;Camin, 2010;Tassino & Passos, 2010).…”

“…A number of studies of reproduction in solitary subterranean rodents have been conducted, but many of these have focussed on laboratory housed animals (Altuna, Franscoli & Izquierdo, ; Bennett et al ., ; Gazit, Shanas & Terkel, ) given the difficulties of studying subterranean rodents in the field (Rado & Terkel, ; Rado, Terkel & Wollberg, ). The reproductive biology of a number of families of rodent moles have been studied and include Geomys (Wood, ; Vaughan, ), Cannomys (Eisenberg & Maliniak, ), Thomomys (Andersen, ), Georychus and Bathyergus (Bennett et al ., ), Spalax (Heth, Shalgi & Terkel, ; Shanas et al ., ; Gazit, et al ., ), Ctenomys (Weir, ; Camin, ) and Heliophobius (Šumbera et al ., ). Despite these, very little has been published on the East African root rat Tachyoryctes splendens (Family Spalacidae).…”

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“…Subterranean rodents exhibit slow life-histories, which are characterized by slow speed of tissue growth due to a low basal metabolic rate selected for by the high energetic demands of burrowing (Henneman, 1983(Henneman, , 1984Hofman, 1983;Martin, 1984aMartin, , 1984bGlazier 1985) leading to delayed sexual maturity (Busch et al 2000). In Ctenomys talarum and C. mendocinus gestation lasts around 95 days (Zenuto et al 2002;Camin 2010); sexual maturity takes 180-240 days in C. talarum (Busch et al 2000) and presumably adult vocalizations have been reported long before sexual maturity at 65-70 days (Zenuto et al 2002) and the same pattern is evident in C. mendocinus which reaches sexual maturity around 180-270 days (Camín 2010) and alleged vocal maturity at 70 days (Camín 2010). We lack precise information on the age of sexual maturity in the Anillaco Tuco-Tuco, but the patterns described for C. talarum and C. mendocinus suggest that vocalizations mature well in advance of sexual maturity in Ctenomys.…”

“…where "short calls" presumably conformed only by series occur at 33 days and "long calls" presumably conformed by series and individual notes occur at 70 days (Camín 2010). In contrast, the highly stereotyped pattern of Scotinomys adult song appears de novo in the first vocalization of juveniles after a period of vocal inactivity (Campbell et al 2014).…”

“…This would indicate that the development of vocalization is a product of vocal tract maturation and not of a vocal learning process (Efremova et al 2011). However, juveniles were exposed to adult LRVs from birth until they were captured, and Ctenomys are born with an open auditory meatus (Zenuto et al 2002, Camín 2010). Thus, it remains possible that adult vocalizations heard at an early age have served as an auditory model for the subsequent vocal development.…”