Enclosed nests may provide greater thermal than nest predation benefits compared with open nests across latitudes
Enclosed nests may provide greater thermal than nest predation benefits compared with open nests across latitudes
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DOI：
10.1111/1365-2435.12819
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发表时间：
2017-06-01
影响因子：
5.2
通讯作者：
Bin Soudi, Evertius E.
中科院分区：
文献类型：
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作者：
Martin, Thomas E.;Boyce, Andy J.;Bin Soudi, Evertius E.
巢结构被认为提供了对一些分类群具有适应性结果的好处。传统上，减少巢穴捕食被认为是巢结构进化的主要利益，而热利益被认为是次要的甚至不存在的因素。然而，这些因素在巢结构中的相对作用在很大程度上仍未被探索。封闭的巢有一个建造的或自然的屋顶，连接到两侧，允许一个有限的开口或管状入口，提供除入口以外的所有方向的覆盖，而开放的巢是上面开放的杯状或平台。研究表明，与北温带地区相比，热带和南半球地区的鸣鸟（雀形目）建造封闭式鸟巢更为常见。这种地理模式可能反映了捕食风险的选择，长期以来，人们一直认为南方地区的巢穴捕食率更高，封闭的巢穴比开放式的巢穴更容易被捕食。因此，我们比较了5个共存鸟类群落中114种不在树洞筑巢的鸣鸟和205种不在树洞筑巢的鸣鸟的封闭和开放巢穴的捕食率，这些物种分布在北温带、热带和南半球地区。在两个南温带生境中，封闭巢的捕食率低于开放巢，而在两个热带生境和北温带生境中，封闭巢的捕食率均低于开放巢。根据文献资料，不同纬度的巢型对巢的捕食没有差异。在我们的野外研究和文献中，在319个物种中，封闭的巢穴并没有显示出减少捕食的一致好处，事实上，热带地区的捕食率并不总是更高，这与长期以来的观点相反。基于三个间接结果表明封闭巢的热效益。首先，在共存物种和文献中发现的物种中，建造封闭式巢穴的物种比使用开放式巢穴的物种要小。较小的物种损失热量最快，因此可能从减少对流冷却中获得重要的热效益。其次，在封闭巢穴的物种中，卵子由父母加热的时间较短，如果卵子冷却速度较慢，这是可以预料的。最后，与使用开放式巢穴的物种相比，使用封闭式巢穴的物种表现出更高的质量和翅膀增长，这表明降低的体温调节成本可以增加生长所需的能量。因此，封闭的巢穴可能比捕食巢穴提供更一致的热量，这与长期以来的观点相反。A可用于本文。
Nest structure is thought to provide benefits that have fitness consequences for several taxa. Traditionally, reduced nest predation has been considered the primary benefit underlying evolution of nest structure, whereas thermal benefits have been considered a secondary or even non-existent factor. Yet, the relative roles of these factors on nest structures remain largely unexplored. Enclosed nests have a constructed or natural roof connected to sides that allow a restricted opening or tube entrance that provides cover in all directions except the entrance, whereas open nests are cups or platforms that are open above. We show that construction of enclosed nests is more common among songbirds (Passeriformes) in tropical and southern hemisphere regions than in north temperate regions. This geographic pattern may reflect selection from predation risk, under long-standing assumptions that nest predation rates are higher in southern regions and that enclosed nests reduce predation risk compared with open cup nests. We therefore compared nest predation rates between enclosed vs. open nests in 114 songbird species that do not nest in tree holes among five communities of coexisting birds, and for 205 non-hole-nesting species from the literature, across northern temperate, tropical, and southern hemisphere regions. Among coexisting species, enclosed nests had lower nest predation rates than open nests in two south temperate sites, but not in either of two tropical sites or a north temperate site. Nest predation did not differ between nest types at any latitude based on literature data. Among 319 species from both our field studies and the literature, enclosed nests did not show consistent benefits of reduced predation and, in fact, predation was not consistently higher in the tropics, contrary to long-standing perspectives. Thermal benefits of enclosed nests were indicated based on three indirect results. First, species that built enclosed nests were smaller than species using open nests both among coexisting species and among species from the literature. Smaller species lose heat fastest and thereby may gain important thermal benefits from reduced convective cooling. Second, eggs were warmed by parents for less time in species with enclosed nests, as can be expected if egg cooling rates are slower. Finally, species using enclosed nests exhibited enhanced growth of mass and wings compared with species using open nests, suggesting reduced thermoregulatory costs allowed increased energy for growth. Enclosed nests may therefore provide more consistent thermal than nest predation benefits, counter to long-standing perspectives.A is available for this article.