Abundance–occupancy relationships in metapopulations: examples of rock pool Daphnia
Abundance–occupancy relationships in metapopulations: examples of rock pool Daphnia
复制标题
混合种群中的丰度-占据关系：岩石池水蚤的例子
作者：
Ö. Östman
在许多物种中，丰度和占用率之间的种内正相关关系表明，相同的过程驱动着局部和区域物种动态。两组主要的机制解释了这种关系：由于栖息地质量的变化而导致的当地人口增长率的时空变化，或者当当地物种丰富时增加物种占用的分散效应。一些研究表明，种群增长率的时空变化与丰度-占用率呈正相关，但很少有研究显示种群的分散效应。据信，这种影响对于那些分散有限的物种，例如元种群，应该更为明显，但这些研究有限。本文研究了岩石池中3个水蚤亚种群的丰度-占比关系，以及散布或生境质量对其局部丰度和发生的影响程度。水蚤和大水蚤的丰度-占用率呈正相关，而水蚤的丰度-占用率呈负相关。没有一个单一的生态因子可以解释任何给定物种的丰度-占用关系。相反，分散过程和岩池质量（主要是盐度和深度）似乎共同作用，形成了丰度-占用关系。这一结论也得到了天然岩石池移民实验的支持。本研究表明，虽然丰度-占用关系通常存在于元种群中，但分散过程和生境质量的变化都可能是决定经历生境异质性的元种群丰度-占用关系的因素。
Intraspecific positive relationships between abundance and occupancy are observed for many species, suggesting that the same processes drive local and regional species dynamics. Two main groups of mechanisms explain this relationship: spatiotemporal variation in local population growth rates due to variation in habitat quality, or dispersal effects that increase occupancy of a species when locally abundant. Several studies show that spatiotemporal variation in population growth rates causes positive abundance–occupancy relationships, but few have shown dispersal effects. It is believed that such effects should be more evident for species whose dispersal is limited, e.g. metapopulations, but those studies are limited. This study investigates abundance–occupancy relationships in three Daphnia metapopulations in rock pools and the degree to which dispersal or habitat quality affect their local abundances and occurrence. Daphnia longispina and Daphnia magna showed positive abundance–occupancy relationships, but not Daphnia pulex. No single ecological factor could explain the abundance–occupancy relationships of any given species. Instead, dispersal processes and rock pool quality (mainly salinity and depth) seem to act together to shape the abundance–occupancy relationships. Such a conclusion is also supported by an immigration experiment in natural rock pools. This study suggests that although positive abundance–occupancy relationships may be commonly found for metapopulations, both dispersal processes and variation in habitat quality can be factors determining the abundance–occupancy relationship of metapopulations experiencing habitat heterogeneity.