Dental anomalies in the atlantic population of south american sea lion, Otaria byronia (Pinnipedia, Otariidae): evolutionary implications and ecological approach
Dental anomalies in the atlantic population of south american sea lion, Otaria byronia (Pinnipedia, Otariidae): evolutionary implications and ecological approach
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南美海狮大西洋种群的牙齿异常，Otaria byronia（鳍足纲，Otariidae）：进化意义和生态方法
DOI：
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
J. O. Menegheti
中科院分区：
文献类型：
--
作者：
C. J. Drehmer;M. E. Fabián;J. O. Menegheti
我们分析了南美洲海狮大西洋种群516个标本中的62个标本中的63例牙齿异常，Otaria byronia de Blainville, 1820。其中上犬牙后6颗（第二磨牙）缺失53例，上颌或下颌多牙缺失7例，双尖牙缺失2例；还有一例牙齿缩小。考虑到系统发育框架中包括所有耳科物种和基翅足类，缺失后犬6可能与耳科逐渐减少和失去牙齿（发育不全）的进化趋势有关。在1816年的Otaria Peron和1866年的Phocarctos Peters中出现的上后犬6通常被认为是一个原始的特征。或者，当采用另一种进化过程时，这可以被解释为Otaria/ phocarcartos进化基的分类返祖现象。下颌外齿与Otaria byronia齿列中自发返祖性的一个具体案例有关，即向像中新世pinnipediform Pteronarctos这样的古老种群倒退。其他异常-上颌多牙，“双齿”；缩牙和缩牙分别是由于牙齿形态发生下的表观遗传系统受到干扰，导致牙胚复制、合并或牙胚复制和缩牙。耳牛牙配方表现出高度的变异性，这种变异性必须考虑到他们的系统发育关系和他们的进化史。从生态学的角度来看，牙齿畸形不影响寿命，与饮食项目或环境干扰无关，但这些观点需要更仔细的研究。
We analyzed 63 cases of dental anomalies from 62 specimens of a total sample of 516 specimens of the Atlantic population of South American sea lions, Otaria byronia de Blainville, 1820. The anomalies were represented by 53 cases of missing upper post-canine 6 (second molars), seven cases of maxillary or mandibular extra teeth, two cases of 'dentes geminatis'; and one case of reduced teeth. Considering a phylogenetic framework where all otariid species and basal Pinnipedimorpha are included, missing post-canine 6 could be related to evolutionary trends in Otariidae towards a progressive reduction and loss of teeth (agenesis). The occurrence of the upper post-canine 6 in Otaria Peron, 1816 as in Phocarctos Peters, 1866 is usually regarded as a primitive character. Alternatively, when adopting another cladistic procedure, this could be interpreted as a taxic atavism at the base of Otaria/Phocarctos clade. Extra-mandibular teeth are related to a concrete case of spontaneous atavism in the dentition of Otaria byronia , in retrogression to ancient groups like the Miocene pinnipediform Pteronarctos Barnes, 1989. The other anomalies - maxillary extra teeth, 'dentes geminati'; and reduced teeth - are caused by some disturbance on the epigenetic system underlying dental morphogenesis leading to duplication, coalescence or duplication and reduction of the dental germ, respectively. Dental formula in Otaria byronia shows a high degree of variability and this variability must be considered in the light of their phylogenetic relationships and their evolutionary history. The ecological approach suggests that dental anomalies do not affect longevity, and are unrelated to dietary items or environmental disturbances, but these points need more careful studies.
影响因子：
4.6
作者：
H. R. Dassule;P. Lewis;M. Bei;R. Maas;Andy McMahon
通讯作者：
H. R. Dassule;P. Lewis;M. Bei;R. Maas;Andy McMahon