Pogány Akos, Szentirmai István, Komdeur Jan, Székely Tamás
Department of Ethology, Eötvös University, Pázmány Péter S. 1/C, Budapest, H-1117, Hungary.
BMC Evol Biol. 2008 Sep 1;8:242. doi: 10.1186/1471-2148-8-242.
The trade-off between current and future parental investment is often different between males and females. This difference may lead to sexual conflict between parents over care provisioning in animals that breed with multiple mates. One of the most obvious manifestations of sexual conflict over care is offspring desertion whereby one parent deserts the young to increase its reproductive success at the expense of its mate. Offspring desertion is a wide-spread behavior, and its frequency often varies within populations. We studied the consistency of offspring desertion in a small passerine bird, the Eurasian penduline tit Remiz pendulinus, that has an extremely variable breeding system. Both males and females are sequentially polygamous, and a single parent (either the male or the female) incubates the eggs and rears the young. About 28-40% of offspring are abandoned by both parents, and these offspring perish. Here we investigate whether the variation in offspring desertion in a population emerges either by each individual behaving consistently between different broods, or it is driven by the environment.
Using a three-year dataset from Southern Hungary we show that offspring desertion by females is consistent between nests. Male desertion, however, depends on ambient environment, because all males desert their nests early in the season and some of them care late in the season. Therefore, within-population variation in parental care emerges by sexually different mechanisms; between-individual variation was responsible for the observed pattern of offspring desertion in females, whereas within-individual variation was responsible for the observed pattern in males.
To our knowledge, our study is the first that investigates repeatability of offspring desertion behavior in nature. The contrasting strategies of the sexes imply complex evolutionary trajectories in breeding behavior of penduline tits. Our results raise an intriguing question whether the sexual difference in caring/deserting decisions explain the extreme intensity of sexual conflict in penduline tits that produces a high frequency of biparentally deserted (and thus wasted) offspring.
当前与未来亲代投资之间的权衡在雄性和雌性之间往往存在差异。这种差异可能导致在与多个配偶繁殖的动物中，亲代之间在养育后代方面产生性冲突。性冲突在养育后代方面最明显的表现之一是后代遗弃，即一方亲代遗弃幼崽以牺牲其配偶为代价来提高自身的繁殖成功率。后代遗弃是一种广泛存在的行为，其频率在种群内部也常常有所不同。我们研究了一种小型雀形目鸟类——欧亚攀雀（Remiz pendulinus）后代遗弃行为的一致性，这种鸟具有极其多样的繁殖系统。雄性和雌性都是顺序性一夫多妻制，并且由单亲（雄性或雌性）孵化卵并养育幼崽。大约28% - 40%的后代被双亲遗弃，这些后代会死亡。在此，我们探究种群中后代遗弃行为的差异是源于每个个体在不同窝之间行为的一致性，还是由环境驱动的。
利用来自匈牙利南部的三年数据集，我们发现雌性的后代遗弃行为在不同巢穴间具有一致性。然而，雄性的遗弃行为取决于环境，因为所有雄性在季节早期都会遗弃巢穴，而其中一些会在季节后期进行养育。因此，种群内部亲代养育行为的差异是由性别不同的机制导致的；个体间差异导致了观察到的雌性后代遗弃模式，而个体内差异导致了观察到的雄性后代遗弃模式。
据我们所知,我们的研究是首个调查自然界中后代遗弃行为可重复性的研究。两性截然不同的策略意味着攀雀繁殖行为有着复杂的进化轨迹。我们的研究结果提出了一个有趣的问题，即养育/遗弃决策中的性别差异是否解释了攀雀中性冲突的极端强度，而这种性冲突导致了高频率的双亲遗弃（因而被浪费掉）的后代。
