scholarly journals History and evolution of the afroalpine flora: in the footsteps of Olov Hedberg

Alpine Botany ◽  
2021 ◽  
Author(s):  
Christian Brochmann ◽  
Abel Gizaw ◽  
Desalegn Chala ◽  
Martha Kandziora ◽  
Gerald Eilu ◽  
...  
Keyword(s):  
Parallel Evolution ◽  
Sky Islands ◽  
Niche Modelling ◽  
Long Distance ◽  
Pleistocene Climate ◽  
Modelling Studies ◽  
Intrapopulation Genetic Variation ◽  
New Evidence ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractThe monumental work of Olov Hedberg provided deep insights into the spectacular and fragmented tropical alpine flora of the African sky islands. Here we review recent molecular and niche modelling studies and re-examine Hedberg’s hypotheses and conclusions. Colonisation started when mountain uplift established the harsh diurnal climate with nightly frosts, accelerated throughout the last 5 Myr (Plio-Pleistocene), and resulted in a flora rich in local endemics. Recruitment was dominated by long-distance dispersals (LDDs) from seasonally cold, remote areas, mainly in Eurasia. Colonisation was only rarely followed by substantial diversification. Instead, most of the larger genera and even species colonised the afroalpine habitat multiple times independently. Conspicuous parallel evolution occurred among mountains, e.g., of gigantism in Lobelia and Dendrosenecio and dwarf shrubs in Alchemilla. Although the alpine habitat was ~ 8 times larger and the treeline was ~ 1000 m lower than today during the Last Glacial Maximum, genetic data suggest that the flora was shaped by strong intermountain isolation interrupted by rare LDDs rather than ecological connectivity. The new evidence points to a much younger and more dynamic island scenario than envisioned by Hedberg: the afroalpine flora is unsaturated and fragile, it was repeatedly disrupted by the Pleistocene climate oscillations, and it harbours taxonomic and genetic diversity that is unique but severely depauperated by frequent bottlenecks and cycles of colonisation, extinction, and recolonisation. The level of intrapopulation genetic variation is alarmingly low, and many afroalpine species may be vulnerable to extinction because of climate warming and increasing human impact.

scholarly journals Territoriality and the organization of technology during the Last Glacial Maximum in southwestern Europe

2019 ◽  
Author(s):  
João Cascalheira
Keyword(s):  
Last Glacial Maximum ◽  
Cultural Transmission ◽  
Adaptive Systems ◽  
Glacial Maximum ◽  
Morphological Data ◽  
Long Distance ◽  
Last Glacial ◽  
Southern Iberia ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Climate changes that occurred during the Last Glacial Maximum (LGM) had significant consequences in human eco-dynamics across Europe. Among the most striking impacts are the demographic contraction of modern humans into southern refugia and the potential formation of a population bottleneck. In Iberia and southern France transformations also included the occurrence of significant technological changes, mostly marked by the emergence of a diverse set of bifacially-shaped stone projectiles. The rapid dissemination of bifacial technologies and the geographical circumscription of specific projectile morphologies within these regions have been regarded as evidence for: (1) the existence of a system of long-distance exchange and social alliance networks; (2) the organization of human groups into cultural facies with well-defined stylistic territorial boundaries. However, the degree and modes in which cultural transmission have occurred within these territories, and how it may have influenced other domains of the adaptive systems, remains largely unknown. Using southern Iberia as a case-study, this paper presents the first quantitative approach to the organization of lithic technology and its relationship to hunter-gatherers' territorial organization during the LGM. Similarities and dissimilarities in the presence of metric and morphological data describing lithic technologies are used as a proxy to explore modes and degrees of cultural transmission. Statistical results show that similarities in technological options are dependent on the chronology and geographical distance between sites and corroborate previous arguments for the organization of LGM settlement in Southern Iberia into discrete eco-cultural facies.

Box Gully: new evidence for Aboriginal occupation of Australia south of the Murray River prior to the last glacial maximum

2007 ◽  
Vol 42 (1) ◽  
pp. 1-11 ◽  
Author(s):  
THOMAS RICHARDS ◽  
CHRISTINA PAVLIDES ◽  
KERYN WALSHE ◽  
HARRY WEBBER ◽  
ROCHELLE JOHNSTON
Keyword(s):  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Last Glacial ◽  
Murray River ◽  
New Evidence ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Evolution of Scaphinotus petersi (Coleoptera: Carabidae) and the role of climate and geography in the Madrean sky islands of southeastern Arizona, USA

2013 ◽  
Vol 79 (2) ◽  
pp. 274-283 ◽  
Author(s):  
Sara Gran Mitchell ◽  
Karen A. Ober
Keyword(s):  
Population Genetic ◽  
Regional Climate ◽  
Sky Islands ◽  
Conifer Forests ◽  
Mountain Ranges ◽  
Genetic Patterns ◽  
Madrean Sky Islands ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractGeographically isolated environments such as the conifer forests atop the Madrean “sky islands” in southeastern Arizona provide natural laboratories for studying factors involved in speciation and origins of biodiversity. Using molecular and geospatial analyses, we examine beetle population phylogeny, regional climate records, and the Quaternary paleobiogeography of forests to evaluate four hypothetical scenarios regarding the current geographic and population genetic patterns of Scaphinotus petersi. Scaphinotus petersi is a large, flightless beetle that resides in the Madrean conifer forests above ~ 1900 m asl. Our results do not support the current hypothesis that S. petersi populations found on seven separate mountain ranges are genetically distinct and separated as temperatures warmed after the Last Glacial Maximum (LGM). Rather, we show that only some of the ranges hold genetically distinct populations, and the timing of separation among the populations does not appear to coincide with specific climatic events such as warming trends. In addition, we show that predicted changes to the climate of the Madrean sky islands may result in the disappearance of S. petersi from some of the lower ranges by the end of this century.

Wetter or colder during the Last Glacial Maximum? Revisiting the pluvial lake question in southwestern North America

2004 ◽  
Vol 62 (3) ◽  
pp. 280-288 ◽  
Author(s):  
Kirsten M. Menking ◽  
Roger Y. Anderson ◽  
Nabil G. Shafike ◽  
Kamran H. Syed ◽  
Bruce D. Allen
Keyword(s):  
Last Glacial Maximum ◽  
Late Pleistocene ◽  
Annual Runoff ◽  
Glacial Maximum ◽  
Water Runoff ◽  
Last Glacial ◽  
Pleistocene Climate ◽  
Surface Water Runoff ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Well-preserved shorelines in Estancia basin and a relatively simple hydrologic setting have prompted several inquiries into the basin's hydrologic balance for the purpose of estimating regional precipitation during the late Pleistocene. Estimates have ranged from 86% to 150% of modern, the disparity largely the result of assumptions about past temperatures. In this study, we use an array of models for surface-water runoff, groundwater flow, and lake energy balance to examine previously proposed scenarios for late Pleistocene climate. Constraints imposed by geologic evidence of past lake levels indicate that precipitation for the Last Glacial Maximum (LGM) may have doubled relative to modern values during brief episodes of colder and wetter climate and that annual runoff was as much as 15% of annual precipitation during these episodes.

scholarly journals THE DYNAMICS OF HISTORICAL AND RECENT RANGE SHIFTS IN THE RUFFED GROUSE (Bonasa umbellus)

2020 ◽  
Author(s):  
Utku Perktaş
Keyword(s):  
Ecological Niche ◽  
Demographic History ◽  
Ecological Niche Modelling ◽  
Ruffed Grouse ◽  
Bonasa Umbellus ◽  
Effective Population ◽  
Niche Modelling ◽  
Range Dynamics ◽  
The Last Glacial Maximum ◽  
The Last Glacial

ABSTRACTClimate variability is the most important force affecting distributional range dynamics of common and widespread species with important impacts on biogeographic patterns. This study integrates phylogeography with distributional analyses to understand the demographic history and range dynamics of a widespread bird species, the Ruffed Grouse (Bonasa umbellus), under several climate change scenarios. For this, I used an ecological niche modelling approach, together with Bayesian based phylogeographic analysis and landscape genetics, to develop robust inferences regarding this species’ demographic history and range dynamics. The model’s predictions were mostly congruent with the present distribution of the Ruffed Grouse. However, under the Last Glacial Maximum bioclimatic conditions, the model predicted a substantially narrower distribution than the present. The predictions for the Last Glacial Maximum also showed three allopatric refugia in south-eastern and west-coast North America, and a cryptic refugium in Alaska. The prediction for the Last Interglacial showed two separate distributions to the west and east of the Rocky Mountains. In addition, the predictions for 2050 and 2070 indicated that the Ruffed Grouse will most likely show slight range shifts to the north and will become more widely distributed than in the past or present. At present, effective population connectivity throughout North America was weakly positively correlated with Fst values. That is, the species’ distribution range showed a weak isolation-by-resistance pattern. The extended Bayesian Skyline Plot analysis, which provided good resolution of the effective population size changes over the Ruffed Grouse’s history, was mostly congruent with ecological niche modelling predictions for this species. This study offers the first investigation of the late-Quaternary history of the Ruffed Grouse based on ecological niche modelling and Bayesian based demographic analysis. The species’ present genetic structure is significantly affected by past climate changes, particularly during the last 130 kybp. That is, this study offers valuable evidence of the ‘expansion–contraction’ model of North America’s Pleistocene biogeography.

New evidence for an independent Wisconsin-age ice cap over Newfoundland

1970 ◽  
Vol 7 (6) ◽  
pp. 1374-1382 ◽  
Author(s):  
Ian A. Brookes
Keyword(s):  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Last Glacial ◽  
Ice Cap ◽  
Early View ◽  
New Evidence ◽  
The Last Glacial Maximum ◽  
The Last Glacial

A reinterpretation of the relative ages of glacial striae in southwestern Newfoundland, and new evidence from erratic till-boulder provenances there, support an early view, since abandoned, that at the last glacial maximum the island supported its own ice cap and was not affected by ice from Labrador.

New evidence for high discharge to the Chukchi shelf since the Last Glacial Maximum

2007 ◽  
Vol 68 (2) ◽  
pp. 271-279 ◽  
Author(s):  
Jenna C. Hill ◽  
Neal W. Driscoll ◽  
Julie Brigham-Grette ◽  
Jeffrey P. Donnelly ◽  
Paul T. Gayes ◽  
...  
Keyword(s):  
Sea Level ◽  
High Discharge ◽  
Incised Valley ◽  
Base Level ◽  
Subbottom Profiling ◽  
New Evidence ◽  
Level Lowering ◽  
Chukchi Shelf ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractUsing CHIRP subbottom profiling across the Chukchi shelf, offshore NW Alaska, we observed a large incised valley that measures tens of kilometers in width. The valley appears to have been repeatedly excavated during sea level lowering; however, the two most recent incisions appear to have been downcut during the last sea level rise, suggesting an increase in the volume of discharge. Modern drainage from the northwestern Alaskan margin is dominated by small, low-discharge rivers that do not appear to be large enough to have carved the offshore drainage. The renewed downcutting and incision during the deglaciation and consequent base level rise implies there must have been an additional source of discharge. Paleoprecipitation during deglaciation is predicted to be at least 10% less than modern precipitation and thus cannot account for the higher discharge to the shelf. Glacial meltwater is the most likely source for the increased discharge.

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