Sakai Sharleen T, Whitt Blake, Arsznov Bradley M, Lundrigan Barbara L
Department of Psychology, Michigan State University, East Lansing, Michigan, USA.
Neuroscience Program, Michigan State University, East Lansing, Michigan, USA.
Brain Behav Evol. 2018;91(2):65-81. doi: 10.1159/000487427. Epub 2018 Apr 10.
The purpose of this study was to examine the pattern of postnatal brain growth in two wild canid species: the coyote (Canis latrans) and gray wolf (Canis lupus). Adult regional and total brain volume differences were also compared between the two species as well as within each species by sex. Three-dimensional virtual endocasts of endocranial airspace were created from computed tomography scans of 52 coyote skulls (28 female, 24 male; 1 day to 13.4 years) and 46 gray wolf skulls (25 female, 21 male; 1 day to 7.9 years). Age was known in coyotes or estimated from dentition patterns in wolves. The 95% asymptotic growth of the endocranium is completed by 21 weeks in male and 17.5 weeks in female coyotes and by 27 weeks in male and 18.5 weeks in female wolves. These ages are well before age at first reproduction (coyote - 40.4 weeks; wolf - 91.25 weeks). Skull growth as measured by centroid size lags behind endocranial growth but is also completed before sexual maturity. Intra- and interspecific comparisons of brain volumes in the adult wolves and coyotes revealed that relative anterior cerebrum (AC) volume was greater in males than females in both species. Relative brain size was greater in the coyote than in the wolf as was relative cerebrum volume. However, relative AC volume and relative cerebellum and brainstem volume was greater in the wolf than coyote. One explanation for the increased AC volume in males compared to females may be related to the role of social information processing. However, additional data are needed to determine the correspondence between regional volumes and functional differences either between or within these species. Nonetheless, these findings provide important baseline data for further studies on wild canid brain variations and development.
郊狼（Canis latrans）和灰狼（Canis lupus）出生后脑生长的模式。还比较了这两个物种之间以及每个物种内按性别划分的成体区域脑容量和总脑容量差异。通过对52个郊狼头骨（28只雌性，24只雄性；1天至13.4岁）和46个灰狼头骨（25只雌性，21只雄性；1天至7.9岁）进行计算机断层扫描，创建了颅腔内空域的三维虚拟脑模型。郊狼的年龄已知，灰狼的年龄则根据牙齿萌出模式估算。雄性郊狼在21周时完成颅腔95%的渐近生长，雌性郊狼在17.5周时完成；雄性灰狼在27周时完成，雌性灰狼在18.5周时完成。这些年龄远早于首次繁殖的年龄（郊狼为40.4周；灰狼为91.25周）。通过质心大小测量的头骨生长落后于颅腔生长，但也在性成熟之前完成。对成年灰狼和郊狼脑容量的种内和种间比较显示，两个物种中雄性的相对前脑（AC）体积均大于雌性。郊狼的相对脑大小和相对大脑体积均大于灰狼。然而，灰狼的相对AC体积以及相对小脑和脑干体积大于郊狼。雄性AC体积相对于雌性增加的一种解释可能与社会信息处理的作用有关。然而，需要更多数据来确定这些物种之间或物种内部区域体积与功能差异之间的对应关系。尽管如此，这些发现为进一步研究野生犬科动物大脑变异和发育提供了重要的基线数据。
