Domestication differentially affects cochlear nucleus subdivisions in the gerbil

Abstract

We analyzed the effects of domestication on the subdivisions of the cochlear nucleus in the gerbil (Meriones unguiculatus) by comparing their volumes and rostrocaudal extents in laboratory gerbils and in age-matched F1 offspring of gerbils caught in the wild. In addition, soma size was systematically analyzed in the anteroventral cochlear nucleus of both groups. Total cochlear nucleus volume and rostrocaudal extent were not significantly different between groups either for young (postnatal day 9) animals before the onset of hearing or for young 4-month-old animals. However, the dorsal cochlear nucleus was significantly larger and the anteroventral cochlear nucleus was significantly smaller in young adults of the wild strain. Thus the relative proportions of the cochlear nucleus subdivisions differed between the groups. In addition, soma size was significantly larger in the low-frequency portion of the anterovental cochlear nucleus in domesticated gerbils compared to wild gerbils. To our knowledge, this is the first reported instance of a well-defined brain structure (e.g., the antreovental cochlear nucleus) being larger in the domesticated than in the wild form.

Strain-dependence of age-related cochlear hearing loss in wild and domesticated Mongolian gerbils

“…Since there are various physiological changes, the sensory systems could be affected, also. Anatomical data show, for example, that domestication differentially affects cochlear nucleus subdivisions in gerbils (Gleich et al, 2000). The primary aim of the present study was to evaluate possible effects of domestication on cochlear sensitivity and to assess if age-dependent deterioration of hearing as it is described for gerbils (e.g., Mills et al, 1990;Schmiedt et al, 1990;Tarnowski et al, 1991;Boettcher et al, 1993Boettcher et al, , 1996Sinnott et al, 1997;Hamann et al, 2002) or mice (Jacobson et al, 2003;Guimaraes et al, 2004) differs between domesticated and wild-type gerbils.…”

Age-Dependent Changes of Gap Detection in the Mongolian Gerbil ( Meriones unguiculatus )

“…Initially, the data from RB and SC gerbils were analyzed separately because differences with respect to the morphology of the cochlear nucleus (CN) and in psychophysical, performance had been reported when comparing laboratory gerbils bred in captivity for many generations with gerbils originating from animals recently collected in the wild (Sinnott et al 1997;McGinn and Faddis 1998;Gleich et al 2000). Thus, it is possible that gerbils from colonies being bred separately for decades differ from one another.…”

“…This is consistent with our earlier observation that RB and SC gerbils were not different with respect to their puretone thresholds (Hamann et al 2002). Despite the reported difference between laboratory and wildstem gerbils in CN morphology (McGinn and Faddis 1998;Gleich et al 2000) and the degree of age-dependent threshold elevation for the detection of vowels (Sinnott et al 1997), gap-detection thresholds from our young RB gerbils closely resembled those of young wild-stem gerbils (Wagner et al 2003). All 14 gap-detection thresholds determined at levels greater than 30 dB SL by Wagner et al (2003) in 6 young gerbils were below 4 ms.…”

Methods and Routes of two German-Mongolian Zoological Expeditionsthrough the Steppe, Semi-Desert and Desert Zones of Mongolia in 1995 and 2002

“…Reduction is greater in the cerebellum as in the forebrain (Leybold 2000). A reduction was also observed in the dorsal part of the cochlear nucleus (CN), whereas the size of its anteroventral part increased (Gleich et al 2000 Mammal biodiversity and abundance determined by the SDM2002 expedition. The results on biodiversity obtained in 1995 and 2002 must be interpreted separately.…”

“…lower brain weight (Stuermer et al 1997), less genetic variability (Neumann et al 2001), higher testosterone concentration and increased rate in spermatogenesis (Blottner et al 2000) indicated domestication in LAB gerbil. Further studies on wild offspring investigated the size of different brain subdivisions (Gleich et al 2000, Leybold 2000 and provided a method to determine age classes through skull characteristics (Tittmann 2002).…”