Peacock Mary M, Smith Andrew T
Department of Zoology, Arizona State University, AZ 85287-1501, USA, , , , , , US.
Oecologia. 1997 Nov;112(4):524-533. doi: 10.1007/s004420050341.
Habitat fragmentation is becoming increasingly common, yet, the effect of habitat spatial structure on population dynamics remains undetermined for most species. Populations of a single species found in fragmented and nonfragmented habitat present a rare opportunity to examine the effect of habitat spatial structure on population dynamics. This study investigates the impact of highly fragmented habitat on dispersal patterns, mating behavior, and genetic variation in a pika (Ochotona princeps) population with a mainland-island spatial structure. Juvenile dispersal patterns in fragmented habitat revealed that individuals tended to disperse to neighboring habitat patches. However, within-patch band-sharing scores from multilocus DNA fingerprints did not differ from what would be expected if individuals were assorting randomly among habitat patches each year. Multiple, short-distance dispersal targets for juveniles and occasional long-distance dispersal events suggest that habitat fragmentation on this scale has not resulted in restricted dispersal and a genetically subdivided population. Although pikas tended to mate with the closest available partner, DNA fingerprinting band-sharing scores between mated pairs were consistent with a random mating hypothesis. Random mating in this population appears to be an incidental effect of dispersal in a fragmented habitat. This pattern is distinct from that found in nonfragmented habitat (large talus patches) where mating was non-random and consistent with mating between individuals of intermediate relatedness. DNA fingerprinting data revealed within-species variation in the mating habits of the pika directly attributable to habitat spatial structure.
栖息地破碎化正变得越来越普遍，然而，对于大多数物种而言，栖息地空间结构对种群动态的影响仍未确定。在破碎化和未破碎化栖息地中发现的单一物种种群，为研究栖息地空间结构对种群动态的影响提供了难得的机会。本研究调查了具有大陆 - 岛屿空间结构的鼠兔（高原鼠兔）种群中高度破碎化栖息地对扩散模式、交配行为和遗传变异的影响。破碎化栖息地中的幼体扩散模式表明，个体倾向于扩散到相邻的栖息地斑块。然而，多位点DNA指纹图谱的斑块内带共享分数与个体每年在栖息地斑块间随机分布时的预期值并无差异。幼体的多个短距离扩散目标和偶尔的长距离扩散事件表明，这种规模的栖息地破碎化并未导致扩散受限和种群的遗传细分。尽管鼠兔倾向于与最近的可用配偶交配，但配对个体之间的DNA指纹图谱带共享分数与随机交配假说一致。该种群中的随机交配似乎是破碎化栖息地中扩散的附带效应。这种模式与在未破碎化栖息地（大型岩屑堆斑块）中发现的模式不同，在未破碎化栖息地中交配是非随机的，且与中等亲缘关系个体之间的交配一致。DNA指纹图谱数据揭示了鼠兔交配习性的种内变异直接归因于栖息地空间结构。
