A variety of plant seedlings suffer most from competition when planted with close relatives, and grow best when planted alongside distant relatives in field soils, researchers from Case Western Reserve University and the University of California, Davis, have found.
And, when seeds of the same species are buried among relatives in the field, the seeds germinate at a higher rate and grow better early in life in close relatives' habitats than distant relatives' habitats.
The work will be published in the Proceedings of the National Academy of Sciences March 14.
The findings, which have implications for Darwin's naturalization hypothesis, invasive species and responses to climate change, come from one of the basic quests in ecology, said Jean H. Burns, a professor of biology at Case Western Reserve.
"One of our goals is to understand what mechanisms drive community assembly, why some species co-exist and why others can't," she said.
Darwin predicted that newcomers that are most distantly related to established species in an ecological community would be the most successful colonizers. Close relatives might compete for the same resources, if they have the same or similar strategies.
This idea has been called Darwin's naturalization hypothesis, and is predicated on the idea that close relatives, being more similar, will compete more strongly with one another than distant relatives.
Burns and Sharon Y. Strauss, a biology professor at the U.C. Davis Center for Population Biology, set up a series of experiments to test whether more closely-related species are more ecologically similar than distantly-related species, and can relatedness thus be used to make predictions about species coexistence?
In a lath house, they planted seedlings of 12 focal species of angiosperms, a diverse group of seed plants, in four groupings: alone in pots and with plants of the same species, the same genus, and
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Case Western Reserve University