Though giant tortoises are the Galápagos' most iconic species, their numbers continued to drop until the 1960s, when the park and the Charles Darwin Research Station began to focus on restoring the most endangered populations. Species decline is often incremental and invisible, even when species are well understood. The place that inspired Darwin's theory of evolution almost 200 years ago is still attracting scientists studying natural selection and species diversity. The death of Lonesome George marked the fourth extinction among the 15 species that evolved on the Galápagos. The death of Lonesome George marked the fourth extinction among the 15 distinct species that evolved on the islands. Today less than 10 percent of an estimated 200,000 original tortoises remain. Early colonists continued the destruction by importing goats, rats, and other invasive species. Massive numbers had already been wiped out by pirates and 19th-century whalers. When Charles Darwin visited the Galápagos Islands in 1835, hundreds of thousands of giant tortoises were clambering around the spiny shrubs and cacti amid active volcanoes.
Others, known as saddlebacks, evolved on the lower, arid islands, where they developed a shell raised in front to help them reach pads of prickly pears. Some, known as domed tortoises, lived in the moist wooded highlands of the larger islands, grazing on the abundant forbs and grasses. Giant tortoises arrived at least a million years ago, gradually colonizing most of the larger islands and adapting over time to their varied conditions. Some of the 32 giant tortoises retrieved from Wolf Volcano will live in the same pen near park headquarters where Lonesome George spent his final years.
0 kommentar(er)
