作者: John J. Just , Jeanne Kraus-Just , Deborah Ann Check
DOI: 10.1007/978-1-4613-3246-6_9
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摘要: The survival of any species depends on its producing enough viable offspring so that the average a single reproductive adult is replaced by another during lifetime. In this regard, phylum Chordata has utilized two approaches. first and probably more primitive approach production large numbers unprotected eggs. This strategy used some in all chordate classes excluding birds mammals.