Reproductive seasonality in captive wild ruminants: implications for biogeographical adaptation, photoperiodic control, and life history
Reproductive seasonality in captive wild ruminants: implications for biogeographical adaptation, photoperiodic control, and life history
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圈养野生反刍动物的繁殖季节性：对生物地理适应、光周期控制和生活史的影响
DOI：
10.1111/j.1469-185x.2012.00238.x
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发表时间：
2012
影响因子：
10
通讯作者：
D. W. Müller
中科院分区：
文献类型：
--
作者：
P. Zerbe;M. Clauss;D. Codron;Laurie Bingaman Lackey;Eberhard Rensch;J. Streich;J. Hatt;D. W. Müller
许多反刍动物物种表现出季节性繁殖模式。造成这种现象的原因受到广泛争论，包括对资源季节性可用性的适应（来自热带地区的身体状况或高纬度栖息地的光周期现象的线索）和/或针对捕食者的防御策略。迄今为止的结论仅限于少于 30 个物种的数据集。在这里，我们使用温带动物园圈养的 110 种野生反刍动物的数据集来定量描述它们的繁殖模式 [将出生高峰宽度 (BPB) 确定为 80% 的出生发生的天数]；然后我们将这种模式与各种生物学特征联系起来（起源纬度、母幼关系（隐藏者/追随者）、自然饮食中草的比例（放牧/浏览）、性别大小二态性/交配系统），并将其与自由放养动物的报告进行比较。当比较分类学亚组时，BPB 的方差与最小 BPB 高度相关，但与最大 BPB 无关，这表明高 BPB（即非季节性繁殖模式）是反刍动物的拟态特征。在全球范围内，自然起源的纬度与圈养中观察到的 BPB 高度相关，支持光周期现象对反刍动物繁殖的压倒性影响。饲喂类型无附加影响；隐藏者/追随者二分法与“沼泽”的反捕食者策略相关，仅对非洲物种子集产生额外影响。性别体型二态性和交配系统与 BPB 略有相关，这可能表明季节性条件下促进了一夫多妻制。如果绝对日长是高度季节性物种的主要触发因素，则圈养种群与报告的自由放养种群之间计算的儒略受孕日期的差异对应于预期的差异：自由放养种群和圈养种群之间受孕时的计算日长遵循 y = x 关系。只有 11 个物种（全部来自低纬度地区）被认为在野生和圈养之间显着改变了它们的繁殖模式，其中 10 个物种在人类照料下变得不那么季节性（但不是非季节性），这表明在野外观察到的季节性在一定程度上与资源相关。只有一种物种（Antidorcas marsupialis）在圈养中变得更具季节性，大概是因为野生资源的可用性推翻了先天的光周期反应。繁殖季节性解释了体重与妊娠期关系的额外差异，季节性物种越多，其体型的妊娠期越短。我们得出的结论是，光周期现象，特别是绝对日长，是遗传上固定的繁殖触发因素，在某种程度上可能会受到身体状况的影响，而妊娠长度的可塑性是一个重要的促进因素，可以部分解释反刍动物辐射到高纬度地区的成功。涉及季节性繁殖的反捕食策略的证据仅限于非洲物种。降雨模式后的生殖季节性可能不是为了适应在资源丰富的时期生育，而是为了只在身体状况良好时才允许受孕。
Many ruminant species show seasonal patterns of reproduction. Causes for this are widely debated, and include adaptations to seasonal availability of resources (with cues either from body condition in more tropical, or from photoperiodism in higher latitude habitats) and/or defence strategies against predators. Conclusions so far are limited to datasets with less than 30 species. Here, we use a dataset on 110 wild ruminant species kept in captivity in temperate‐zone zoos to describe their reproductive patterns quantitatively [determining the birth peak breadth (BPB) as the number of days in which 80% of all births occur]; then we link this pattern to various biological characteristics [latitude of origin, mother‐young‐relationship (hider/follower), proportion of grass in the natural diet (grazer/browser), sexual size dimorphism/mating system], and compare it with reports for free‐ranging animals. When comparing taxonomic subgroups, variance in BPB is highly correlated to the minimum, but not the maximum BPB, suggesting that a high BPB (i.e. an aseasonal reproductive pattern) is the plesiomorphic character in ruminants. Globally, latitude of natural origin is highly correlated to the BPB observed in captivity, supporting an overruling impact of photoperiodism on ruminant reproduction. Feeding type has no additional influence; the hider/follower dichotomy, associated with the anti‐predator strategy of ‘swamping’, has additional influence in the subset of African species only. Sexual size dimorphism and mating system are marginally associated with the BPB, potentially indicating a facilitation of polygamy under seasonal conditions. The difference in the calculated Julian date of conception between captive populations and that reported for free‐ranging ones corresponds to the one expected if absolute day length was the main trigger in highly seasonal species: calculated day length at the time of conception between free‐ranging and captive populations followed a y = x relationship. Only 11 species (all originating from lower latitudes) were considered to change their reproductive pattern distinctively between the wild and captivity, with 10 becoming less seasonal (but not aseasonal) in human care, indicating that seasonality observed in the wild was partly resource‐associated. Only one species (Antidorcas marsupialis) became more seasonal in captivity, presumably because resource availability in the wild overrules the innate photoperiodic response. Reproductive seasonality explains additional variance in the body mass–gestation period relationship, with more seasonal species having shorter gestation periods for their body size. We conclude that photoperiodism, and in particular absolute day length, are genetically fixed triggers for reproduction that may be malleable to some extent by body condition, and that plasticity in gestation length is an important facilitator that may partly explain the success of ruminant radiation to high latitudes. Evidence for an anti‐predator strategy involving seasonal reproduction is limited to African species. Reproductive seasonality following rainfall patterns may not be an adaptation to give birth in periods of high resource availability but an adaptation to allow conception only at times of good body condition.