State the form of natural selection that happened in the G. fortis population on Daphne Major because of the drought.
Fig. 5.2 displays the distribution of bill size in the G. fortis population before the drought in 1977. Draw a new curve on Fig. 5.2 to represent the distribution of bill size in the G. fortis population after the drought.
Explain how natural selection in the G. fortis population on Santa Cruz has produced the bill-size distribution shown in Fig. 5.3.
Scientists investigated how an increase in the annual number of tourists affected the number of invasive alien species found in the Galápagos islands. Over many years, they recorded the number of invasive alien species present each year in the Galápagos islands. They also recorded the number of tourists who visited the islands each year. Fig. 5.4 presents a graph of the data for five different years during the study.
Using Table 5.1, explain why an $r$ value of $0.930$ shows that there is a significant correlation between the number of tourists and the number of invasive alien species.
Invasive alien species are thought to have contributed to extinctions recorded in the Galápagos islands. Discuss the negative effects that introducing invasive alien species can have on an ecosystem.
State two factors, apart from competition and the introduction of invasive alien species, that can lead to extinction.