This conclusion is supported by archaeometric data showing that archaeological sites contain many unweaned pups, confirming the presence of temperate-latitude breeding colonies in California, the Pacific Northwest, and the eastern Aleutian mTOR inhibitor Islands. SIA of ontogenetic series from ancient temperate-latitude rookeries indicates that young were weaned at 12 mo or more, as in most other

eared seals, and not in 4 mo as in surviving populations of northern fur seals. Thus the collapse of ancient temperate latitude rookeries coincided with a major change in the life history and reproductive biology of the species. The relative roles of human hunting vs. climatic factors in explaining these ecological and behavioral shifts are unclear and the focus of ongoing research. The last example involves an extinct species, Steller’s sea cow (Hydrodamalis gigas). This was the largest sirenian BGB324 manufacturer species (up to 5 m long) and the only one inhabiting temperate and subarctic waters. Steller’s sea cow was discovered by western explorers on the Commander Islands in 1741 and was driven to extinction by overhunting by 1768 (Anderson and Domning 2002, Turvey and Risley

2006). The species had a wider distribution in the Pleistocene, from Japan to the Aleutians to southern California. In a study of archaeological and paleontological materials, Savinetsky et al. (2004) discovered that sea cows were more abundant

in warm intervals and argued that cooling may have limited them to the Commander Islands prior to contact with Western hunters. Other authors have attributed range retraction to hunting by native peoples (Anderson and Domning 2002). In any case, the relict population observed in the 18th century fed in kelp forests; Galeterone it is unclear if such behavior characterized the species across its entire geographic range. Corbett et al. (2008) measured the isotopic composition of historical and fossil specimens attributed to Steller sea cows to understand the generality of kelp feeding and as a tool to understand whether bone fragments attributed to the species were correctly identified. Specimens that were unambiguously identified as sea cows (historical specimens from the Commander Islands and Pleistocene-aged fossils from the Aleutians and California) have collagen and bioapatite δ13C values and collagen δ15N values consistent with a diet rich in kelp. Thus the sea cows in the relict population on the Commander Islands had diets similar to those of animals in warmer regions where they may have been more abundant. In contrast, among the archaeological materials, only the samples from Kiska Island resembled extant or paleontological sea cows. Based on isotopic data, Corbett et al.