HEARING IN PRIMITIVE MAMMALS - MONODELPHIS-DOMESTICA AND MARMOSA ELEGANS
HEARING IN PRIMITIVE MAMMALS - MONODELPHIS-DOMESTICA AND MARMOSA ELEGANS
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DOI：
10.1016/0378-5955(94)90088-4
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发表时间：
1994-06-01
期刊：
影响因子：
2.8
通讯作者：
MASTERTON, RB
中科院分区：
文献类型：
--
作者：
FROST, SB;MASTERTON, RB
虽然Didelphidae科的负鼠通常作为追踪现代哺乳动物的耳学和神经学进化的一个吝啬的起点，但Didelphid opossums的听力学数据仅适用于北美负鼠（Didelphis virginiana），由于其体型庞大，可能是该科最不具代表性的属之一。本报告将听力学数据扩展到另外两种Didelphid负鼠，Monodelphis arctica和Marmosa elegans。在60 dB SPL时，Monodelphis的听力范围为3.6 kHz至77 kHz，最佳灵敏度范围为8至64 kHz，而Marmosa的听力范围为3.8 kHz至80 kHz，最佳灵敏度范围为8至64 kHz。这两个物种被发现是特别敏感的音调，平均最低阈值接近20分贝SPL的Monodelphis和33分贝SPL的旱獭。这些结果表明，像北美负鼠属是敏感的高频率，但相对不敏感的声音。由于Didelphids的三个属的听力在几个方面一致，因此可以得出结论，对高频的敏感性几乎肯定存在于古代哺乳动物中，可能在获得3个听小骨中耳连接后很快就出现了。高频听力的实用价值，而不是高度敏感的听力，可能是这种形态转变的选择压力的主要来源。
Although opossums of the Family Didelphidae usually serve as a parsimonious starting point for tracing the otological and neurological evolution of modern mammals, audiological data for Didelphid opossums is available only for the North American opossum (Didelphis virginiana) which because of its large size, may be one of the least representative genera of the family. The present report extends the audiological data to two other species of Didelphid opossums, Monodelphis domestica, and Marmosa elegans. At 60 dB SPL, the hearing of Monodelphis extends from 3.6 kHz to 77 kHz, with a range of best sensitivity from 8 to 64 kHz while the hearing of Marmosa extends from 3.8 kHz to 80 kHz, with a range of best sensitivity from 8 to 64 kHz. Neither species was found to be particularly sensitive to tones, with the average lowest threshold near 20 dB SPL for Monodelphis and 33 dB SPL for Marmosa. These results indicate that like the North American opossum both genera are sensitive to high frequencies yet relatively insensitive to sound. Because the hearing of the three genera of Didelphids agree in several respects, it can be concluded that sensitivity to high frequencies almost certainly was present in ancient mammals, probably following quickly after the acquisition of a 3 ossicle middle ear linkage. It is not unlikely that the utility value of high frequency hearing, rather than highly sensitive hearing, may have been a primary source of selective pressure for this morphological transformation.