The level of Kluane Lake, the largest lake in Yukon Territory, was lower than at present during most of the Holocene. The lake rose rapidly in the late seventeenth century to a level 12 m above present, drowning forest and stranding driftwood on a conspicuous high-stand beach, remnants of which are preserved at the south end of the lake. Kluane Lake fell back to near its present level by the end of the eighteenth century and has fluctuated within a range of about 3 m over the last 50 yr. The primary control on historic fluctuations in lake level is the discharge of Slims River, the largest source of water to the lake. We use tree ring and radiocarbon ages, stratigraphy and sub-bottom acoustic data to evaluate two explanations for the dramatic changes in the level of Kluane Lake. Our data support the hypothesis of Hugh Bostock, who suggested in 1969 that the maximum Little Ice Age advance of Kaskawulsh Glacier deposited large amounts of sediment in the Slims River valley and established the present course of Slims River into Kluane Lake. Bostock argued that these events caused the lake to rise and eventually overflow to the north. The overflowing waters incised the Duke River fan at the north end of Kluane Lake and lowered the lake to its present level. This study highlights the potentially dramatic impacts of climate change on regional hydrology during the Little Ice Age in glacierised mountains.

Thirty-five museum specimens collected in 1926 and 1947–48 vouch for the distinctiveness of an undescribed large mammal, a form of lechwe antelope. Their preservation has allowed comparative analyses of morphological characters to reveal this new species, the Upemba lechwe Kobus anselli sp. nov. It is most similar to the black lechwe K. smithemani and quite distinct from all other known taxa, including topotypical red lechwes K. leche. Prevailing threats and conservation concerns underwrite its formal description after neglect by science for decades. This lechwe is restricted to the Upemba wetlands, Kamalondo depression, south-east Congo basin (Katanga Province, Democratic Republic of Congo), and has declined greatly since the 1970s. Commercial poaching through the 1980s reduced c. 20000 individuals to under 1000 estimated today. Recognition of K. anselli as a distinct evolutionary entity was previously ignored, because the entrenched taxonomy assumed it was just another red lechwe. Its speciation seems to be recent, probably Pleistocene. Lechwes evolved in an archipelago of wetlands formed through vicariance of a more extensive drainage system, the Palaeo-Chambeshi, which extended from Katanga and north-east Zambia across the south-central African plateau, into the Kalahari basin. The Palaeo-Chambeshi was a major endoreic tributary of Palaeo-Lake Makgadikgadi. Its fragmentation isolated lechwes in the Kamalondo depression from wetlands in the Upper Zambezi–Okavango, Upper Kafue, and the Chambeshi and Luapula drainages. The belated discovery of K. anselli emphasizes the region's conservation significance. Because of its high species richness and high endemism, Katanga is a biodiversity hotspot within the encompassing Katanga–Chambeshi region, also covering eastern Angola and much of Zambia. A secure future for the critically endangered Upemba lechwe hinges on reducing adverse human impact and maintaining the integrity of its wetland habitat. Support for protected areas is critical. Maintenance of ecological processes, focused on aquatic systems, is especially important to conserve biodiversity. Recognition of the complex evolutionary history of the region (since the Late Neogene) underpins the scientific foundation for all conservation plans and activities. It prescribes why a regional conservation strategy should encompass the landscape mosaic, structured across neighbouring drainage systems (Lufira, Upper Lualaba and Chambeshi–Luapula rivers). A trans-frontier conservation area will consolidate the protected areas and land use systems of the region in an ecological context.