Iguana Decline In 1987, Martin Wikelski began a long-term study of marine iguanas in the Galápagos Islands. He marked iguanas on two islands—Genovesa and Santa Fe—and collected data on how their body size, survival, and reproductive rates varied over time. He found that because iguanas eat algae and have no predators, deaths usually result from food shortages, disease, or old age. In January 2001, an oil tanker ran aground and leaked a small amount of oil into the waters near Santa Fe. FIGURE 44.3 shows the number of marked iguanas that Wikelski and his team counted in their study populations just before the spill and about a year later.
FIGURE 44.3 Shifting numbers of marked marine iguanas on two Galápagos islands. An oil spill occurred near Santa Fe just after the January 2001 census (orange bars). A second census was carried out in December 2001 (green bars).
Which island had more marked iguanas at the time of the first census?
To examine: The Island that has a greater population size of marine during the first census study.
Concept introduction: Marine iguanas are kind of reptiles but unique among the modern lizards. They feed on algae and large species find its food source on the tidal region as they live in rocky shores. These are currently considered as threatened species due to the poaching, negative effects of introduced species, loss, and fragmentation of habitat. Many NGO’s and program researchers have taken part in protecting these species by creating artificial nesting sites.
Explanation of Solution
The research group of Person M conducted the long- term study of marine iguanas in Galapagos Islands. The study on the population of marine iguanas was done on island Gen and island SF in the year 2001. This study tells about their body size, survival, and the reproductive rate over the period of time. During this year, the oil spill occurred near the island SF and led to the loss of marine iguanas species. They observed the population of marked marine iguanas on two islands over the period of a year by conducting two surveys.
Refer Fig. 44.3, “Shifting numbers of marked marine iguanas on two Galapagos islands” in the textbook. The graphical representation shows the number of marked iguanas in island Gen and island SF. Marked iguanas are identified on both islands. The island that had greater number of marked marine iguana population at the time of the first census is island SF.
Compared to island Gen, island SF has more marked marine iguanas during the first census study.
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