October 19, 2007 7:10 AM Subscribe
Social amoebas Dictyostelium discoideum
posted by Kirth Gerson (11 comments total)
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respond to a dwindling food supply by clustering into a multicell colony and moving to a place suitable for making spores.
In the process, some amoebas take on specialized roles. Some of those roles involve sacrificing themselves for the survival of the colony. Individual amoebas that shirk those roles have a lower reproductive rate, and their genes disappear.