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Invasive mammals such as rats are associated with negative impacts on native fauna and their eradication on islands around the world has been proved to result in substantial conservation gains. Fernando de Noronha is an archipelago located off the north-east coast of Brazil and has records of native fauna negatively impacted by introduced rats. We used D-Loop sequences and 14 microsatellite markers to investigate gene flow between three populations of Rattus rattus across two islands of Fernando de Noronha. Using both methods we found very great differentiation between the two islands, indicating very low or no gene flow. Our findings suggested if Rata Island were cleared of rats it would have a low probability of reinvasion occurring from the main island. Thus, we recommend an eradication program be implemented on Rata Island following the successful program on nearby Meio Island.

In this paper, an overview of introduced cat and rodent impacts on islands, and methods for their control and eradication, are presented. Fernando de Noronha, an inhabited oceanic island of Brazil, is used as a case study to illustrate the challenges of cat and rodent management on inhabited islands. Cat impacts have been recorded for 175 vertebrate species, and rat impacts for 173 plant and animal species. Eradication of cats and rodents for species conservation has been successful on small to medium- sized uninhabited or sparsely inhabited islands. However, examples of successful cat and rodent management programmes for biodiversity on inhabited islands are limited. On inhabited islands localised control of cats and rodents occurs, but historically with a focus on agriculture, human livelihoods and animal welfare, and only more recently on native species conservation. Control of cats and rodents on inhabited islands for species conservation lags behind uninhabited islands and the reasons for this are social and complex. Conservation managers often perceive a lack of support from island residents or administrators, which may or may not actually be the case. Where support does not exist, it may relate to the provisioning of control versus eradication, the techniques proposed, or wider socioeconomic issues. This ultimately translates to conservation inaction, and the ongoing decline and extinction of island fauna. Abundance estimates for cats and density estimates for rats on Fernando de Noronha are presented, along with documented biodiversity impacts, to support recommendations for future management on Fernando de Noronha.

The diversity of introduced mammals and their introduction history varies greatly across the Western Indian Ocean (WIO) islands, from ancient introductions in the past millennia on islands off the East coast of Africa where extant terrestrial native mammal communities exist, to very recent invasions in the past decades on islands in the Mascarene archipelago. We compile the distribution of 16 introduced mammal taxa on 28 island groups comprising almost 2000 islands. Through an exhaustive literature review and expert consultation process we recorded all mammal eradications, and species recoveries which could be attributed to introduced mammal eradication or control. All island groups have been invaded by mammals, and invasive cats and rats in particular are ubiquitous, but cultural contingency has also led to regional invasions by other mammals such as lemurs, civets and tenrecs. Mammal eradications have been attempted on 45 islands in the WIO, the majority in the Seychelles and Mauritius, and where successful have resulted in spectacular recovery of species and ecosystems. Invasive mammalian predator eradication or control in association with habitat management has led to improved conservation prospects for at least 24 species, and IUCN red-list down-listing of eight species, in the Mascarene Islands. Future island conservation prioritisation in the region will need to take account of global climate change and predicted sea-level rises and coastal inundation. Greater investment and prioritisation in island conservation in the region is warranted, given its high biodiversity values and the extent of invasions.

The corpulent JCR:LA-cp rat (cp/cp) is a useful model for study of the metabolic consequences of obesity and hyperinsulinemia. To assess the effect of hyperinsulinemia on VLDL secretion in this model, we measured rates of secretion of VLDL in perfused livers derived from cp/cp rats and their lean littermates. Livers of cp/cp rats secreted significantly greater amounts of VLDL triglyceride and apolipoprotein, compared with lean littermates. The content of apoB, apoE, and apoCs in both perfusate and plasma VLDL was greater in the cp/cp rat, as was the apolipoprotein (apo)C, apoA-I, and apoA-IV content of plasma HDL. Triglyceride content was also greater in cp/cp livers, as was hepatic lipogenesis and expression of lipogenic enzymes and sterol regulatory element binding protein-1 (SREBP-1). Hepatic mRNAs for apoE, and apoA-I were higher in livers of cp/cp rats. In contrast, the steady state levels of apoC-II, apoC-III, and apoB mRNAs were unchanged. Thus, livers of obese hyperinsulinemic cp/cp JCR:LA-cp rats secrete a greater number of VLDL particles that are enriched in triglyceride, apoE, and apoC. Greater secretion of VLDL in the cp/cp rat in part results from higher endogenous fatty acid synthesis, which in turn may occur in response to increased expression of the lipogenic enzyme regulator SREBP-1c.—Elam, M. B., H. G. Wilcox, L. M. Cagen, X. Deng, R. Raghow, P. Kumar, M. Heimberg, and J. C. Russell. Increased hepatic VLDL secretion, lipogenesis, and SREBP-1 expression in the corpulent JCR:LA-cp rat. J. Lipid Res. 2001. 42: 2039–2048.