ecotype (plural ecotypes) (ecology) A group of organisms, normally a subdivision of a species, that is adapted to a specific environment. 1995, C. Wayne Smith, Crop Production: Evolution, History, and Technology, page 234: These four Japanese introductions probably were of the Japonica ecotype. 1997, Steven R. Radosevich, Jodie S. Holt, Claudio Ghersa, Weed Ecology: Implications for Management page 78, She collected rhizomes of two ecotypes, a northern ecotype originally from Yellowstone County, Montana, and a southern ecotype from an agricultural field near Hollister, California. 1997, Mark R. Macnair, The evolution of plants in metal-contaminated environments, in Rudolf Bijlsma, Volker Loeschcke (editors), Environmental Stress, Adaptation, and Evolution, page 19,