the effects of evolution and artificial selection on genes. In particular, the genomics of domesticated species allow for the study of strong artificial selection, founder events and bottlenecks, as well as wider evolutionary questions. The process of domestication, by which only a choice few wild individuals are cultivated and selected against, often results in very strong selective pressures. This is evident in the genomes of these individuals as a lack of genetic diversity. In some cases this lack of diversity is seen as a selective sweep, whereby the variation at a particular locus of the genome is highly reduced while variation outside of this area is maintained or only partially reduced. In other cases, such as the coconut, genomic studies have revealed occurrences of a founder event, whereby the genetic diversity of an entire population is reduced due to a small number of individuals with low diversity being the isolated ancestors of a larger modern population. Bottlenecks, where variation is reduced throughout the entire genome, are also evident in crop species such as pearl millet, cotton, common bean and lima bean. With the identification of bottlenecks in these species, researchers are able to study the effects on an organisms' ability to evolve past a bottleneck, and what effects this may have on the genomes of both individuals and populations as well as their fitness. Domesticated species and human history Domesticated species and the human populations that domesticate them are typified by a mutualistic relationship of interdependence. Domesticated crop species tend to become increasingly reliant on human populations for dispersal due to the selection against natural seed dispersal methods and humans have become increasingly dependent on domesticated crop species to sustain growing populations. Because many crop species rely on humans for dispersal, and it is possible to use genomics to track the dispersal of domesticated species, the genomics of domesticated species can be used as a tool to track human movements throughout history. Bottle gourd The bottle gourd (Lagenaria siceraria) is a domesticated species that originated in Africa and was dispersed throughout Asia by 9000 B.C.E. and reached the Americas by 8000 B.C.E. Morphologically and genetically, the Asian and African bottle gourds are sufficiently different that they can be designated as two separate subspecies. Morphologically the American gourd resembles the African gourds more than the Asian gourds, which was previously used as support for the theory that the American variety is