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Extinctions have altered island ecosystems throughout the late Quaternary. Here, we review the main historic drivers of extinctions on islands, patterns in extinction chronologies between islands, and the potential for restoring ecosystems through reintroducing extirpated species. While some extinctions have been caused by climatic and environmental change, most have been caused by anthropogenic impacts. We propose a general model to describe patterns in these anthropogenic island extinctions. Hunting, habitat loss and the introduction of invasive predators accompanied prehistoric settlement and caused declines of endemic island species. Later settlement by European colonists brought further land development, a different suite of predators and new drivers, leading to more extinctions. Extinctions alter ecological networks, causing ripple effects for islands through the loss of ecosystem processes, functions and interactions between species. Reintroduction of extirpated species can help restore ecosystem function and processes, and can be guided by palaeoecology. However, reintroduction projects must also consider the cultural, social and economic needs of humans now inhabiting the islands and ensure resilience against future environmental and climate change.

Insular communities are particularly vulnerable to anthropogenic extinctions and introductions. Changes in composition of island frugivore communities may affect seed dispersal within the native plant community, risking ecological shifts and ultimately co-extinction cascades. Introduced species could potentially mitigate these risks by replacing ecological functions of extinct species, but conclusive evidence is lacking. Here, we investigate changes in plant–frugivore interactions involving frugivorous birds, mammals and reptiles in Mauritius, an oceanic island with an exceptionally well-specified frugivore community and well-described species introduction history. We demonstrate substantial losses of binary interaction partnerships (at the species level) resulting from native species extinctions, but also gains of equal numbers of novel interactions with introduced species, potentially supporting the idea that non-native species might compensate for lost seed dispersal. However, closer investigation of animal seed handling behaviour reveals that most interactions with seed dispersers are replaced by ecologically different interactions with seed predators. Therefore, restoration of seed dispersal functionality in this novel plant–frugivore community is unlikely. Many plant species depend on frugivores for seed dispersal. Here, the authors investigate plant-frugivore networks in Mauritius, finding that the new interactions gained from the arrival of non-native seed predators are unlikely to compensate for the extinction of seed dispersers.

The Pleistocene vertebrate assemblage of Aldabra Atoll has been comparatively well studied. Three Upper Pleistocene fossil localities have been described yielding birds, reptiles and terrestrial molluscs. Those of Bassin Cabri and Bassin Lebine on Ile Picard are undated but must be in excess of 136,000 YBP, whereas Point Hodoul on Malabar Island is circa 100,000 YBP. Aldabra was seemingly completely submerged between deposition of the Ile Picard and Point Hodoul deposits, resulting in local faunal extinctions. Here we present the results of an ongoing study of fossil material collected on Ile Picard in 1987, which reveals a more diverse assemblage than previously realised. Notable discoveries are an Ardeola heron, three Procellariformes, tropic-bird Phaethon, gull Larus, rail Dryolimnas, harrier Circus and owl Tyto, plus evidence of recolonisation of the atoll by some seabirds, rail, harrier, owl, giant tortoises and lizards after the Ile Picard/Point Hodoul submergence event.

Island birds that were victims of anthropic extinctions were often more specialist species, having evolved their most distinctive features in isolation, making the study of fossil insular birds most interesting. Here we studied a fossil cranium of the ‘giant’ extinct scops owl Otus murivorus from Rodrigues Island (Mascarene Islands, southwestern Indian Ocean), to determine any potential unique characters. The fossil and extant strigids were imaged through X-ray microtomography, providing 3D views of external and internal (endocast, inner ear) cranial structures. Geometric morphometrics and analyses of traditional measurements yielded new information about the Rodrigues owl’s evolution and ecology. Otus murivorus exhibits a 2-tier “lag behind” phenomenon for cranium and brain evolution, both being proportionately small relative to increased body size. It also had a much more developed olfactory bulb than congeners, indicating an unexpectedly developed olfactory sense, suggesting a partial food scavenging habit. In addition, O. murivorus had the eyes placed more laterally than O. sunia , the species from which it was derived, probably a side effect of a small brain; rather terrestrial habits; probably relatively fearless behavior; and a less vertical posture (head less upright) than other owls (this in part an allometric effect of size increase). These evolutionary features, added to gigantism and wing reduction, make the extinct Rodrigues owl’s evolution remarkable, and with multiple causes.

Aim The islands of the south‐western Indian Ocean region are home to many endemic bird species, with their closest relatives occurring in Africa and Madagascar, Eurasia, the Sunda Islands, and the Australasian region. Among owls, the extant endemic scops owls (genus Otus) from Madagascar, Comoros, Seychelles, and Socotra are related to the Southeast Asian species, O. sunia, the Oriental scops owl. Three owl species, presumably Otus derivatives, twice the size of standard scops owls and now extinct, once inhabited the Mascarene Islands, and have been placed in a separate genus, Mascarenotus. Insular apomorphies have made their precise relationships difficult to determine. Here we investigate the phylogenetic position of these enigmatic owls. Location The Mascarene Islands (Réunion, Mauritius, Rodrigues) in the south‐western Indian Ocean. Methods Phylogenetic relationships were reconstructed using ancient DNA extracted from subfossil remains. Fragments of cytochrome b gene were amplified and sequenced. The ancient sequences were analysed with modern sequences of 19 ingroup Otus taxa using Bayesian and Maximum Likelihood methods. Results The Mauritian extinct species M. sauzieri was reconstructed as the sister to both O. pauliani (Grand Comoro) and O. rutilus (Madagascar). The Rodrigues extinct species M. murivorus was the sister, in a star‐like differentiation, to the preceding clade as well as the remaining Comorian species and a clade formed by O. insularis (Seychelles) and O. sunia. Main conclusions The ancestor of O. sunia simultaneously colonized Rodrigues Island (evolving into Otus murivorus), Madagascar, and part of the Comoros Islands around 3 million years ago. Later, presumably from Madagascar, new lineages colonized Grand Comoro and Mauritius (O. sauzieri). Independently, a more recent O. sunia ancestor colonized the Seychelles Islands and Socotra. These colonizations were probably favoured by Pliocene cyclonic events, stronger and more frequent than today. Several features, including giantism, wing reduction, and a relative decrease in skull and orbit size evolved convergently in the polyphyletic species O. sauzieri and O. murivorus.

A new fossil site in a previously unexplored part of western Madagascar (the Beanka Protected Area) has yielded remains of many recently extinct vertebrates, including giant lemurs ( Babakotia radofilai , Palaeopropithecus kelyus , Pachylemur sp., and Archaeolemur edwardsi ), carnivores ( Cryptoprocta spelea ), the aardvark-like Plesiorycteropus sp., and giant ground cuckoos ( Coua ). Many of these represent considerable range extensions. Extant species that were extirpated from the region (e.g., Prolemur simus ) are also present. Calibrated radiocarbon ages for 10 bones from extinct primates span the last three millennia. The largely undisturbed taphonomy of bone deposits supports the interpretation that many specimens fell in from a rock ledge above the entrance. Some primates and other mammals may have been prey items of avian predators, but human predation is also evident. Strontium isotope ratios ( 87 Sr/ 86 Sr) suggest that fossils were local to the area. Pottery sherds and bones of extinct and extant vertebrates with cut and chop marks indicate human activity in previous centuries. Scarcity of charcoal and human artifacts suggests only occasional visitation to the site by humans. The fossil assemblage from this site is unusual in that, while it contains many sloth lemurs, it lacks ratites, hippopotami, and crocodiles typical of nearly all other Holocene subfossil sites on Madagascar.

The New World Vulture [ Coragyps ] occidentalis (L. Miller, 1909) is one of many species that were extinct by the end of the Pleistocene. To understand its evolutionary history we sequenced the genome of a 14,000 year old [ Coragyps ] occidentalis found associated with megaherbivores in the Peruvian Andes. occidentalis has been viewed as the ancestor, or possibly sister, to the extant Black Vulture Coragyps atratus , but genomic data shows occidentalis to be deeply nested within the South American clade of atratus . Coragyps atratus inhabits lowlands, but the fossil record indicates that occidentalis mostly occupied high elevations. Our results suggest that occidentalis evolved from a population of atratus in southwestern South America that colonized the High Andes 300 to 400 kya. The morphological and morphometric differences between occidentalis and atratus may thus be explained by ecological diversification following from the natural selection imposed by this new and extreme, high elevation environment. The sudden evolution of a population with significantly larger body size and different anatomical proportions than atratus thus constitutes an example of punctuated evolution. 14,000 year old DNA reveals the evolutionary dynamics and adaptations of South American vultures.

The extinct Laysan Rail or Crake (Zapornia palmeri) was a small, flightless rail endemic to Laysan Island in the northwestern chain of the Hawaiian Archipelago. I detail the collections made, including eggs, nests, juveniles, and numerous adults prior to its extinction. The juvenile plumage was seemingly well documented, but my study of a series of juvenile specimens collected in 1891 and 1896 provides hitherto undescribed molt changes, from downy chick to definitive plumage. Morphometric data show that sexual size dimorphism is present with males being slightly more robust in bill, legs, and feet. I provide a detailed review of the literature showing the chronology of events that led to the extinction of the species and how this easily could have been avoided.

In the light of the currently increasing drought frequency and water scarcity on oceanic islands, it is crucial for the conservation of threatened insular vertebrates to assess how they will be affected. A 4000 yr old fossil assemblage in the Mare Aux Songes (MAS), southwest Mauritius, Mascarene Islands, contains bones of 100 000+ individual vertebrates, dominated by two species of giant tortoises Cylindraspis triserrata and C. inepta, the dodo Raphus cucullatus, and 20 other vertebrate species (Rijsdijk, Hume, Bunnik, Florens, Baider, Shapiro et al. (2009) Mid-Holocene vertebrate bone Concentration-Lagerstätte on oceanic island Mauritius provides a window into the ecosystem of the dodo (Raphus cucullatus). Quaternary Science Reviews 28: 14–24). Nine radiocarbon dates of bones statistically overlap and suggest mass mortality occurred between 4235 and 4100 cal. yr BP. The mortality period coincides with a widely recognized megadrought event. Our multidisciplinary investigations combining geological, paleontological and hydrological evidence suggests the lake was located in a dry coastal setting and had desiccated during this period. Oxygen isotope data from a Uranium-series dated stalagmite from Rodrigues, an island 560 km east of Mauritius, supports this scenario by showing frequently alternating dry and wet periods lasting for decades between 4122 and 2260 cal. yr BP. An extreme drought resulted in falling water-tables at MAS and elsewhere on the island, perhaps deprived these insular vertebrates of fresh water, which led to natural mass mortalities and possibly to extirpations. In spite of these events, all insular species survived until at least the seventeenth century, confirming their resistance to climatic extremes. Despite this, the generally exponential increase of combined human impacts on islands including loss of geodiversity, habitats, and stocks of fresh water, there will be less environmental safe-haven options for insular endemic and native vertebrates during future megadrought conditions; and therefore will be more prone to extinction.

Evidence from DNA phylogeny, Plio-Pleistocene ocean currents, giant tortoise dispersal, evolution of plant defences, radiocarbon dates and archaeology indicates that the endemic giant tortoises on the Mascarenes and Seychelles colonized naturally and were not translocated there by humans.