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Weird Science: Species Flocks

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In some isolated locations, a single species will radiate into many species to fill different ecological roles in the area. These species flocks are all very closely related, and they may evolve in a relatively short amount of time. A famous example of a species flock is the cichlid fishes living in the lakes in east Africa’s Rift Valley (SF Fig. 1.2 A). The lakes are located on a divergent tectonic plate boundary and have changed quickly over time, enabling the fairly rapid evolution of closely related species that are native to relatively small habitats. Some cichlid fish species are found in only one small lake island.

<p><strong>SF Fig. 1.2.</strong> (<strong>A</strong>) Several species of freshwater cichlid fishes from east African Rift Valley lakes</p><br />
<p><strong>SF Fig. 1.2.</strong>&nbsp;<span style="font-size: 13.008px; line-height: 1.538em;">(<strong>B</strong>) Charles Darwin noted the different beak shapes in the beaks of finches from the Galapagos Islands.</span></p><br />


Species flocks are important in the study of evolutionary biology. In fact, the first identified species flock was the finches studied by Darwin in the Galapagos Islands. These finches factored heavily in Darwin’s work on the theory of natural selection. The finches descended from a single ancestor who had arrived on the isolated islands, and over time, diversified to take advantage of the wide variety of ecological roles available. Some finches developed heavy seed-cracking bills, whereas others developed long, narrow bills for grabbing insects (SF Fig. 1.2 B). However, the finches kept many features in common, providing a clue to their close relationship to one another and to their common ancestor.

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Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.