THE ORIGINS OF LACTATION AND THE EVOLUTION OF MILK - A REVIEW WITH NEW HYPOTHESES
THE ORIGINS OF LACTATION AND THE EVOLUTION OF MILK - A REVIEW WITH NEW HYPOTHESES
复制标题
DOI：
10.1111/j.1365-2907.1989.tb00398.x
复制
发表时间：
1989-03-01
期刊：
影响因子：
4.9
通讯作者：
MURPHY, CJ
中科院分区：
文献类型：
--
作者：
BLACKBURN, DG;HAYSSEN, V;MURPHY, CJ
哺乳是哺乳动物繁殖的核心，了解哺乳的起源对于理解哺乳动物的早期进化是必要的。在现代哺乳动物中，哺乳是一个极其复杂的现象，涉及形态、生理、生化、生态和行为适应。因为如此复杂的适应网络不可能从头出现，哺乳一定是从一个简单得多的过程开始的。关于原乳分泌物的原始适应价值的假说援引了体温调节、抗生素、行为或营养功能。在这篇综述中，我们对这些假设进行了评估，并试图根据早期哺乳动物及其祖先的生物学、乳腺的起源、卵泡外营养供应的进化以及乳汁合成和分泌的生理生化等现有概念来重建泌乳的起源。根据经验证据和理论考虑，我们提出了一个渐进的方案，包括以下步骤。首先，卵的孵化是由血管化腹部孵化贴片的发展所辅助的。其次，来自孵育贴片皮腺的抗微生物分泌物提高了卵或后代的存活率。在这个阶段，这些分泌物可能补充了卵磷脂营养（与单孔目动物的输卵管分泌物的方式大致相同），可能是兼性的。随后，皮腺的肥大和特化伴随着大量营养分泌物的控制产生，这些分泌物最终演变成后代发育和生长的主要能量来源。我们概述了牛奶进化中的重要事件，并建议研究可能为所讨论的进化假设提供间接测试。
Lactation is central to mammalian reproduction, and an understanding of the origins of lactation is necessary to comprehend the early evolution of the Class Mammalia. In modern mammals, lactation is a staggeringly complex phenomenon involving morphological, physiological, biochemical, ecological, and behavioural adaptations. Because such a complex web of adaptations could not have arisende novo, lactation must have begun as a much simpler process. Hypotheses regarding the original adaptive value of proto‐lacteal secretions invoke thermoregulatory, antibiotic, behavioural or nutritive functions. In this review, we evaluate each of these hypotheses and attempt to reconstruct the origins of lactation in the light of current concepts of the biology of early mammals and their ancestors, the origin of mammary glands, the evolution of extravitelline nutrient provision, and the physiology and biochemistry of milk synthesis and secretion. Drawing upon empirical evidence and theoretical considerations, we present a gradualistic scenario involving the following steps. First, incubation of eggs was aided by development of a vascularized abdominal incubation patch. Secondly, anti‐microbial secretions from cutaneous glands of the incubation patch enhanced survival of eggs or offspring. At this stage, these secretions could have supplemented vitelline nutrients (in much the same way as oviductal secretions do in monotremes), perhaps facultatively. Subsequently, hypertrophy and specialization of cutaneous glands accompanied the controlled production of a copious, nutritious secretion, which eventually evolved into a primary source of energy for development and growth of the offspring. We outline important events in the evolution of milk, and suggest studies likely to provide indirect tests of the evolutionary hypotheses discussed.