Chapter 2 Chapter Summary

  Taxonomists use morphological and genetic information to describe and identify the world’s species. Places vary in their species richness, the number of species found in a particular location.

  There is genetic variation among individuals within a species. Genetic variation allows species to adapt to a changing environment, including in agriculture. Genomic tools are increasingly important in conservation biology.

  Within an ecosystem, species play different roles and have varying requirements for survival. Certain keystone species are important in determining the ability of other species to persist in an ecosystem.

  It is estimated that there are 6 million to 10 million species, most of which are insects, by some estimates, or bacteria, by others. The majority of the world’s species have still not been described and named; further work is needed to describe microorganisms such as bacteria.

  The greatest biological diversity is found in tropical regions, with particular concentrations of species in rain forests and coral reefs. The ocean may also have great species diversity but needs further exploration.