INTENSE NATURAL SELECTION ON MORPHOLOGY OF CLIFF SWALLOWS (PETROCHELIDON PYRRHONOTA) A DECADE LATER: DID THE POPULATION MOVE BETWEEN ADAPTIVE PEAKS?
INTENSE NATURAL SELECTION ON MORPHOLOGY OF CLIFF SWALLOWS (PETROCHELIDON PYRRHONOTA) A DECADE LATER: DID THE POPULATION MOVE BETWEEN ADAPTIVE PEAKS?
复制标题
DOI：
10.1525/auk.2011.10219
复制
发表时间：
2011-01-01
期刊：
影响因子：
2.8
通讯作者：
Brown, Charles R.
中科院分区：
文献类型：
--
作者：
Brown, Mary Bomberger;Brown, Charles R.
异常的气候事件往往导致对生物体的强烈自然选择。情景选择事件是否会导致永久性的微进化变化，或者在以后的时间被相反的选择压力逆转，这一点很少有人知道，因为大多数研究都没有持续足够长的时间来见证罕见的事件并记录它们的后果。1996年，内布拉斯加州西南部异常寒冷和潮湿的天气导致数千只崖燕（Petochelidon pyrrhonota）在6天内死亡。幸存者的体型更大，翅膀和尾巴更短，翅膀长度的不对称性也比死亡者小。我们确定了轨迹的形态特征，在十年后的这一事件，每年测量一岁的鸟类从1997年至2006年。翅膀和中间的尾羽长度继续减少，喙的长度和宽度继续增加，跗骨长度不变，而翅膀长度的不对称程度增加。在选择后的十年中，翼、尾和喙长的累积方向变化大于选择事件本身。形态变异不能解释的表型可塑性更好的环境条件在生长过程中，因为天气变量（影响食物供应和外寄生）没有显着不同的选择前后。没有证据表明，相反的选择恢复骨骼大小或翅膀或尾巴的长度选择事件之前。在这个人口的形态持续变化的原因尚不清楚，但可能代表人口转移到一个不同的健身高峰在适应性景观的结果，在1996年的激烈选择。接收日期：2010年9月21日，接受日期：2010年10月29日。
Unusual climatic events often lead to intense natural selection on organisms. Whether episodic selection events result in permanent microevolutionary changes or are reversed by opposing selection pressures at a later time is rarely known, because most studies do not last long enough to witness rare events and document their aftermath. In 1996, unusually cold and wet weather in southwestern Nebraska led to the deaths of thousands of Cliff Swallows (Petrochelidon pyrrhonota) over a 6-day period. Survivors were skeletally larger, with shorter wings and tails, and had less asymmetry in wing length than those that died. We determined trajectories of morphological traits in the decade following this event by measuring yearling birds each year from 1997 to 2006. Wing and middle tail-feather lengths continued to decrease, bill length and width continued to increase, tarsus length was unchanged, and levels of asymmetry in wing length increased. Cumulative directional change in wing, tail, and bill length was greater in the decade after selection than during the selection event itself. Morphological variation could not be explained by phenotypic plasticity resulting from better environmental conditions during growth, because weather variables (that influence food supply and ectoparasitism) were not significantly different before and after selection. There was no evidence that opposing selection restored skeletal size or wing or tail length to that before the selection event. The reasons for continued change in morphology in this population are unclear but may represent a population shift to a different fitness peak in the adaptive landscape as a consequence of the intense selection in 1996. Received 21 September 2010, accepted 29 October 2010.