The extinction of the dodo bird (Raphus cucullatus) in the late 17th century is often attributed solely to human hunting and habitat destruction. However, a closer examination reveals that a combination of factors, including introduced species, low reproductive rates, and limited genetic diversity, were more critical to its demise. First, introduced species—such as rats, pigs, and monkeys—devastated dodo nests by eating their eggs and competing for food. These animals arrived on Mauritius with European sailors and quickly overwhelmed the ground-nesting dodo, which had no natural predators and thus no defense mechanisms. Second, dodos had an extremely low reproductive rate, laying only one egg per breeding season. This slow reproduction meant that even small losses to predation or human activity could cause a rapid population decline, as the species could not replenish itself quickly. Third, the dodo’s limited genetic diversity, resulting from its isolation on a small island, made it highly susceptible to diseases and environmental changes. With a small, homogeneous gene pool, the dodo lacked the adaptive resilience to cope with new stressors, such as introduced pathogens or climate fluctuations. Therefore, while human hunting certainly contributed, the primary drivers of dodo extinction were the ecological disruptions caused by invasive species, the bird's reproductive limitations, and its genetic vulnerability.
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The reading’s argument that introduced species, low reproduction, and genetic diversity were the primary causes of dodo extinction is flawed. First, while rats and pigs did eat dodo eggs, human hunting was far more devastating. Historical records show that sailors and settlers killed dodos in large numbers for food, often taking dozens at a time, and they destroyed the dodo’s forest habitat for agriculture and timber. This direct exploitation occurred before invasive species had established significant populations, and it drove the dodo to near-extinction by the 1660s. Second, the claim about low reproductive rates is misleading. Many bird species with low reproductive rates, such as the kakapo, have survived for centuries when their environments are stable. The dodo’s single-egg clutch was only a problem because humans and introduced predators were artificially increasing mortality. In other words, low reproduction was not a root cause but a vulnerability that only became fatal due to human actions. Third, the genetic diversity argument is not supported by evidence. Studies of dodo DNA show that the species had moderate genetic variation, comparable to other island birds that did not go extinct. Moreover, the dodo had evolved in isolation for millions of years, suggesting it was well adapted to its environment. The real cause of extinction was the rapid, unprecedented introduction of humans and their associated species, which the dodo had no evolutionary time to cope with. Thus, the reading overemphasizes secondary factors while downplaying the central role of human activity.
📝 작문 지시 Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific points made in the reading passage.
📊 TOEFL Integrated Writing Rubric
Content Accuracy: Accurately capture the relationship between lecture and reading
Information Completeness: Cover all key counter-arguments from the lecture
Structure & Coherence: Logical organization and progression
Language Use: Grammar, vocabulary, expression accuracy
Scored 0-30 based on holistic scoring (original 0-5, scaled to 30).
