Mating in bighorn sheep: Frequent male reproduction via a high-risk ''unconventional'' tactic
Mating in bighorn sheep: Frequent male reproduction via a high-risk ''unconventional'' tactic
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DOI：
10.1007/s002650050361
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发表时间：
1997-07-01
影响因子：
2.3
通讯作者：
Forbes, SH
中科院分区：
文献类型：
--
作者：
Hogg, JT;Forbes, SH
落基山大角羊在争夺配偶时使用三种不同的策略。两种策略（抚育和阻断）的特点是在相对较长的配偶期（长达3天）内进行防御和合作交配。在coursing战术，下属公羊争取临时交配访问（持续秒），以捍卫母羊占主导地位。通过结合群体范围内的遗传（微卫星）排除的父系，行为数据和模型的大角羊生殖竞争，我们估计，在两个自然种群的142只羔羊的父亲父亲的44%。在一个人口中，成功的防御对coursing的概率是最低的公羊，有许多女性的配偶，并举行最高的统治地位。即便如此，人均年度男性生殖成功率是正相关的社会排名在这两个牛群时，衡量秋季概念。在每个人口（0.36和0.39）与捍卫公羊交配的比例是相似的，以相应的分数的羔羊（0.43和0.47）父亲由coursing公羊，这表明精子竞争近似于一个公平的彩票。男性特征的重要性，在获得社会地位，并获得合作的配偶与母羊不同，并可能与那些需要防御（和实践）课程的冲突。虽然公羊的震荡性武器（角）比其他牛科动物的刺穿性武器危险性小，但福尔斯在奔跑时摔倒和角的打击可能导致死亡，阻碍未来的交配竞争或增加捕食的风险。求偶是一个罕见的例子，一个非传统的替代交配策略是高收益和高风险。
Rocky Mountain bighorn rams use three distinct tactics in competition for mates. Two tactics (tending and blocking) feature defense and cooperative mating over a relatively prolonged consort period (up to 3 days). In the coursing tactic, subordinate rams fight dominants for temporary copulatory access (lasting seconds) to defended ewes. By combining population-wide genetic (microsatellite) exclusion of paternity, behavioral data and a model of bighorn reproductive competition, we estimated that coursing rams fathered 44% of 142 lambs assigned paternity in two natural populations. In one population, the probability of successful defense against coursing was lowest among rams that had many female consorts and held highest dominance rank. Even so, per capita annual male reproductive success was positively associated with social rank in both herds when measured in terms of fall conceptions. The proportion of coursing versus defending ram matings in each population (0.36 and 0.39) was similar to the corresponding fraction of lambs (0.43 and 0.47) fathered by coursing rams, suggesting that sperm competition approximated a fair lottery. Male traits important in gaining social status and obtaining cooperative consorts with ewes were different and potentially in conflict with those needed to defend against (and practise) coursing. Although the concussive weapons (horns) of rams are less dangerous than, for example, the piercing weapons of other bovids, injury from falls and horn blows during coursing brawls may cause death, handicap future mating competition or increase the risk of predation. Coursing is a rare example of an unconventional alternative mating tactic that is high-gain and high-risk.