Holocene glaciations and paleoclimate of mount Kenya and other East African mountains

Mahaney, William C.

doi:10.1016/0277-3791(88)90007-8

Cited by 19 publications

(6 citation statements)

References 17 publications

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“…During Pleistocene and Holocene glacial cycles [28,29], the Lake Victoria region has seen recurrent expansions and retractions of forest and savannah habitat [30-32], so it is safe to assume that the distributional ranges of rainforest specialists like D. wilverthi and savannah/forest generalists like D. molestus have changed accordingly. The two species probably broadly overlapped during glacial periods of maximum forest expansion, when Kakamega Forest was connected to Ugandan rainforests [30], while D. wilverthi has been restricted to forest islands during interglacial periods as is the case at present.…”

Section: Discussionmentioning

confidence: 99%

Hybridization in East African swarm-raiding army ants

et al. 2011

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BackgroundHybridization can have complex effects on evolutionary dynamics in ants because of the combination of haplodiploid sex-determination and eusociality. While hybrid non-reproductive workers have been found in a range of species, examples of gene-flow via hybrid queens and males are rare. We studied hybridization in East African army ants (Dorylus subgenus Anomma) using morphology, mitochondrial DNA sequences, and nuclear microsatellites.ResultsWhile the mitochondrial phylogeny had a strong geographic signal, different species were not recovered as monophyletic. At our main study site at Kakamega Forest, a mitochondrial haplotype was shared between a "Dorylus molestus-like" and a "Dorylus wilverthi-like" form. This pattern is best explained by introgression following hybridization between D. molestus and D. wilverthi. Microsatellite data from workers showed that the two morphological forms correspond to two distinct genetic clusters, with a significant proportion of individuals being classified as hybrids.ConclusionsWe conclude that hybridization and gene-flow between the two army ant species D. molestus and D. wilverthi has occurred, and that mating between the two forms continues to regularly produce hybrid workers. Hybridization is particularly surprising in army ants because workers have control over which males are allowed to mate with a young virgin queen inside the colony.

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Section: Discussionmentioning

confidence: 99%

Hybridization in East African swarm-raiding army ants

et al. 2011

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“…Additionally, area and topography of the glacier surface at different stages since the end of the Little Ice Age have been reconstructed from moraines [Patzelt et al, 1984]. As part of a wider compilation, results of studies on Quaternary glacial history and palaeoclimatology on Mt Kenya were published by Mahaney [1989].…”

Section: Previous Research On Lewis Glaciermentioning

confidence: 99%

Seventy-six years of mean mass balance rates derived from recent and re-evaluated ice volume measurements on tropical Lewis Glacier, Mount Kenya

Prinz

Fischer²,

Nicholson

et al. 2011

Geophys. Res. Lett.

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[1] Lewis Glacier on Mt Kenya has a unique history of detailed study, making it among the best documented tropical glaciers. Here we present (i) a new ice volume determination based on a bedrock DEM constructed from GPR data acquisition and (ii) the glacier's mean mass balance rates over the last 76 years derived from volume and area estimates based on seven historical maps and the newly determined bedrock topography. Total ice volume in 2010 was 1.90 ± 0.30 × 10 6 m 3 with a mean (maximum) ice depth of 18 ± 3 m (45 ± 3 m), which is one order of magnitude larger than previously published values. In 2010, the glacier had lost 90% (79%) of its 1934 glacier volume (area), with the highest rates of ice volume loss occurring around the turn of the century. Computed mean mass balance rates, covering the whole period of glaciological surveys of Lewis Glacier, provide the longest record of tropical glacier change and show that the mean mass balance rate varies consistently with global estimates, but the magnitude is always more negative than in other regions. Citation: Prinz, R., A. Fischer, L. Nicholson, and G. Kaser (2011), Seventy-six years of mean mass balance rates derived from recent and re-evaluated ice volume measurements on tropical Lewis Glacier, Mount Kenya, Geophys. Res. Lett., 38, L20502,

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“…The problem is mainly one of unknown time required to infill small sedimentary basins with organic materials, which may amount to several centuries or even thousands of years. A similar problem occurs in the nearby Wind River Mountains (Mahaney, 1978(Mahaney, ,1988a) and on Mount Kenya (Mahaney, 1987b(Mahaney, , 1988b.…”

Section: Regional Frameworkmentioning

confidence: 99%

“…The Neoglacial is a term originally intended to refer to a resurgence of ice in cirques in western North America (Matthes, 1940). The restriction to the western U.S. has slowly been modified to include other alpine areas such as Mount Kenya (Mahaney, 1988b), Western Europe (Patzelt, 1974;Mahaney, 1987c), and even the Antarctic (Clapperton and Sugden, 1988). It seems to be generally accepted that worldwide ice resurgence occurred from the middle to the late Holocene in many alpine areas.…”

Section: Regional Frameworkmentioning

confidence: 99%

Neoglacial chronology and floristics in the Middle Teton area, central Teton Range, Western Wyoming

Mahaney

Spence

1990

J Quaternary Science

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The relative ages of Neoglacial deposits above 2900m near Cloudveil Dome, Middle Teton, and Teepe glaciers, central Teton Range, western Wyoming, were determined using topographic position, weathering features, lichenometry, vegetation characteristics, and soils. A three-fold deposit sequence is identified and correlated with the Gannett Peak, Audubon and Indian Basin Neoglacial advances described elsewhere in the Teton and nearby Wind River ranges. While soil profile morphology proved very useful in distinguishing deposits of different age, other age indicators such as clay mineralogy and soil chemistry, proved of only marginal value in age discrimination. This chronosequence, emplaced over the last -5000yr, provides an excellent setting upon which to test changes in plant species composition and its use as a relative dating method.Vascular plant species composition cannot be used to discriminate deposits of the different advances, possibly because of random colonisation and establishment combined with extensive mass wasting during the Neoglacial. However, certain vegetation features, such as total cover and species densities, appear useful as relative dating methods. Journal of QuaterGry Science

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Holocene glaciations and paleoclimate of mount Kenya and other East African mountains

Cited by 19 publications

References 17 publications

Hybridization in East African swarm-raiding army ants

Hybridization in East African swarm-raiding army ants

Seventy-six years of mean mass balance rates derived from recent and re-evaluated ice volume measurements on tropical Lewis Glacier, Mount Kenya

Neoglacial chronology and floristics in the Middle Teton area, central Teton Range, Western Wyoming

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