Figure 7.8 Evolution by the founder effect. Water hyacinth is an aquatic plant that was native to South America, where many different genotypes exist, as indicated by the different colored dots. Introductions around the world are thought to have occurred with low numbers of founders. Today, most populations existing outside of South America are represented by a single genotype.

Data from Y.-Y Zhang, D.-Y. Zhang, and S. C. H. Barrett, Genetic uniformity characterizes the invasive spread of water hyacinth (Eichhornia crassipes), a clonal aquatic plant, Molecular Ecology 19 (2010): 1774–1786. Photo by Eastcott-Momatiuk/The Image Works.