The three most abundant Venezuelan columnar cacti, from left to right, Pilosocereus lanuginosus (Linnaeus) Byles & Rowley, Stenocereus griseus (Haworth) Buxbaum, and Cereus repandus (Linnaeus) Miller. These species depend strictly on nectar-feeding bats for their pollination. Bat-mediated gene dispersal confers high levels of genetic exchange among populations of the three species, a process that enhances levels of genetic diversity within their populations.