Adjacent Lowland Areas Research Articles

The formation of the Indo-Pacific montane avifauna

The processes generating the earth’s montane biodiversity remain a matter of debate. Two contrasting hypotheses have been advanced to explain how montane populations form: via direct colonization from other mountains, or, alternatively, via upslope range shifts from adjacent lowland areas. We seek to reconcile these apparently conflicting hypotheses by asking whether a species’ ancestral geographic origin determines its mode of mountain colonization. Island-dwelling passerine birds at the faunal crossroads between Eurasia and Australo-Papua provide an ideal study system. We recover the phylogenetic relationships of the region’s montane species and reconstruct their ancestral geographic ranges, elevational ranges, and migratory behavior. We also perform genomic population studies of three super-dispersive montane species/clades with broad island distributions. Eurasian-origin species populated archipelagos via direct colonization between mountains. This mode of colonization appears related to ancestral adaptations to cold and seasonal climates, specifically short-distance migration. Australo-Papuan-origin mountain populations, by contrast, evolved from lowland ancestors, and highland distribution mostly precludes their further colonization of island mountains. Our study explains much of the distributional variation within a complex biological system, and provides a synthesis of two seemingly discordant hypotheses for montane community formation.

Deep and Frozen: High‐Mountain Lakes as Sentinels of Regional Limnology and Global Environmental Changes

AbstractHigh‐mountain lakes possess tremendous ecological significance and contribute to the well‐being of local mountain population and those living in adjacent lowland areas. Over the years, the structure and function of these ecosystems have experienced significant variations particularly due to the synergistic effects of climate stressors and human perturbations as well as reformed water consumption patterns. However, research on hydrology of mountain lakes remains focused on particular regions and related scientific perspectives on lake ecological shifts are still insufficient. Furthermore, the lack of strong nexus between scientists, stakeholders, and local community also promotes data gaps in mountain paleolimnology. Hence, it should be recognized that investigating the nexus between different stakeholders and global climate shifts as well as investigating the anthropogenic forcing factors in high‐mountain lakes is fundamental for future hydrological studies. New proxy‐based assessments and continuous, high‐frequency limnological measurements will help improve spatiotemporal resolution and address existing data gaps in high‐mountain limnology and paleolimnology.

Computation of backwater effects in surface waters of lowland catchments including control structures – an efficient and re-usable method implemented in the hydrological open-source model Kalypso-NA (4.0)

Abstract. Backwater effects in surface water streams and on adjacent lowland areas caused by mostly complex drainage and flow control structures are not directly computed with hydrological approaches yet. A solution to this weakness in hydrological modelling is presented in this article. The developed method enables transfer of discharges into water levels and calculation of backwater volume routing along streams and adjacent lowland areas by balancing water level slopes. The implemented and evaluated method extends the application of hydrological models for rainfall–runoff simulations of backwater-affected catchments with the advantages of (1) modelling complex flow control systems in tidal backwater-affected lowlands, (2) less effort to parameterise river streams, (3) directly defined input factors of driving forces (climate change and urbanisation) and (4) runtime reduction of 1 to 2 orders of magnitude in comparison to coupled hydrodynamic models. The developed method is implemented in the open-source rainfall–runoff model Kalypso-NA (4.0). Evaluation results show the applicability of the model for simulating rainfall–runoff regimes and backwater effects in an exemplary lowland catchment (Hamburg, Germany) with a complex flow control system and where the drainage is influenced by a tidal range of about 4 m. The proposed method is applicable to answer a wide scope of hydrological and water management questions, e.g. water balances, flood forecasts and effectiveness of flood mitigation measures. It is re-usable to other hydrological numerical models, which apply conceptual hydrological flood-routing approaches (e.g. Muskingum–Cunge or Kalinin–Miljukov).

The mass elevation effect of the Tibetan Plateau and its implications for Alpine treelines

ABSTRACTThe immense and towering Tibetan Plateau (TP) acts as a heating source and shapes the climate of not only the Eurasian continent but also the entire world. The mass elevation effect of the TP was first observed in the 1950s; however, due to the scarcity of meteorological observation stations and limited climatic data, little information on the mass elevation effect of the plateau and its implications for the position of Alpine treelines in the southeastern part of the TP is quantitatively known. This paper compares monthly mean air temperature differences at elevations of 4000, 4500, 5000, 5500 and 6000 m between the main plateau, the Qilian Mts. in the northeastern corner of the plateau and the Sichuan Basin to the east of the plateau to quantify the mass elevation effect of the plateau. The TP air temperature data are retrieved from Terra moderate‐resolution imaging spectroradiometer (MODIS) land surface temperature (LST), and the free‐air temperatures over the westernmost Sichuan Basin are estimated using the measured lapse rate from Mt. Emei, which is located in the western portion of the Sichuan Basin. The results demonstrate the following important characteristics. (1) Owing to the mass elevation effect, air temperatures gradually increase from the eastern edge to the interior main TP. The monthly mean air temperature in the interior main plateau is approximately 2–7 °C higher than in the surrounding mountains and adjacent lowland areas. At an elevation of 4500 m (corresponding to the mean altitude of the TP), the monthly mean temperature differences between the plateau and the Sichuan Basin range from 3.58 °C (April) to 6.63 °C (June); the monthly temperature differences between the plateau and the Qilian Mts. range from 1.6 °C (July) to 7.7 °C (March). (2) The mass elevation effect of the plateau pushes the 10 °C isotherm upward in the warmest month and is indicative of a warmth index of 15 °C month up to elevations of 4600–4700 m, which enables the treeline altitude in the interior TP 500–1000 m higher than along the eastern edge. Therefore, mass elevation effect contributes to the occurrence of the highest treeline in the Northern Hemisphere, which is present on the southeastern TP.

Origin of British and Irish mammals: disparate post-glacial colonisation and species introductions

Origin of British and Irish mammals: disparate post-glacial colonisation and species introductions

The role of physical geography and habitat type in shaping the biogeographical history of a recent radiation of Neotropical marsupials (Thylamys: Didelphidae)

AbstractAimIn this study, we reconstructed the biogeographical history of species within the sister‐genera Thylamys and Lestodelphys, Neotropical marsupials that primarily inhabit open biomes. We used this reconstruction to test the extent to which physical geography (e.g. mountains and rivers) and habitat type (e.g. biomes) shaped patterns of diversification.LocationCentral and southern South America.MethodsA fossil‐calibrated ultrametric tree for all species within Thylamys and Lestodelphys, along with relevant marsupial outgroups, was reconstructed using sequences from 23 nuclear loci and three mitochondrial loci. Using two biogeographical area schemes (based on biomes and physical barriers, respectively), the biogeographical history of this clade was reconstructed using Lagrange, a maximum‐likelihood approach.ResultsThylamys and Lestodelphys originated during the Pliocene in the lowland areas east of the Andes and later expanded their range into and across the Andes. Rivers are implicated in speciation events that occurred in the lowlands, whereas differentiation among habitat types may have led to increased in situ speciation within the Andes.Main conclusionsBiogeographical area schemes based on biomes and physical geographical barriers offered largely complementary results, supporting the hypothesis that both physical geography and ecological differences among habitats drive speciation in continental fauna. Invasion of high‐elevation grasslands may have been the impetus for further diversification in montane habitats, eventually seeding the adjacent lowland areas with additional species.

Le Peuplement Animal du Mont Nimba (Guinée, Côte d'Ivoire, Liberia)Le peuplement animal du Mont Nimba(Guinée, Côte d'Ivoire, Liberia) edited by M. Lamotte & R. Roy . Mémoires du Muséum d'Histoire Naturelle 190.2003. Pp. 724. Price: €137 (hardback). Publications scientifiques du Muséum, Paris. ISBN 2 85653 554 2

Mount Nimba, straddling the borders of three countries, is one of only three peaks (the other two are in Sierra Leone) above 1500 m in tropical West Africa to the west of Mount Cameroon. Thus it has many faunal elements distinct from the adjacent lowland areas. Despite a long history of biological research and the declaration of a Biosphere Reserve and World Heritage Site in 1981, uncontrolled hunting, and open-cast iron ore mining on the Liberian side, has had devastating effects on the environment.

Climate change and mountain water resources: overview and recommendations for research, management and policy

Abstract. Mountains are essential sources of freshwater for our world, but their role in global water resources could well be significantly altered by climate change. How well do we understand these potential changes today, and what are implications for water resources management, climate change adaptation, and evolving water policy? To answer above questions, we have examined 11 case study regions with the goal of providing a global overview, identifying research gaps and formulating recommendations for research, management and policy. After setting the scene regarding water stress, water management capacity and scientific capacity in our case study regions, we examine the state of knowledge in water resources from a highland-lowland viewpoint, focusing on mountain areas on the one hand and the adjacent lowland areas on the other hand. Based on this review, research priorities are identified, including precipitation, snow water equivalent, soil parameters, evapotranspiration and sublimation, groundwater as well as enhanced warming and feedback mechanisms. In addition, the importance of environmental monitoring at high altitudes is highlighted. We then make recommendations how advancements in the management of mountain water resources under climate change could be achieved in the fields of research, water resources management and policy as well as through better interaction between these fields. We conclude that effective management of mountain water resources urgently requires more detailed regional studies and more reliable scenario projections, and that research on mountain water resources must become more integrative by linking relevant disciplines. In addition, the knowledge exchange between managers and researchers must be improved and oriented towards long-term continuous interaction.

Palaeoenvironmental changes and vegetation history of the northern Upper Rhine Graben (southwestern Germany) since the Lateglacial

AbstractThe vegetation of the northern Upper Rhine Graben (southwestern Germany) is reconstructed for the end of the Lateglacial and the Holocene by means of palynological analyses in combination with AMS 14c dating. Analogous to adjacent lowland areas, the Younger Dryas climatic deterioration did not result in a complete deforestation of the area and open pine woodlands with locally birch stands and shrubs persisted. A subdivision of the Younger Dryas period, into a humid first phase, followed by a dry second phase was also reflected in our records. For the Holocene, the pollen diagrams show two regionally different vegetation developments, related to substrate and variations in annual precipitation: in the south the ‘classical’ succession of pine then hazel is followed by other deciduous trees, whereas in the northern part, pine kept its dominance far into the Subboreal.

Phylogeny and biogeography of a large radiation of Andean lizards (Iguania, Stenocercus)

With 61 species occurring mostly in the Andes and adjacent lowland areas, Stenocercus lizards represent one of the most widespread and well‐represented Andean vertebrate groups. Phylogenetic relationships among species of Stenocercus are inferred using different datasets based on mitochondrial DNA sequence data of 35 species and morphological data of 59 species. Among morphological data, polymorphic and meristic/morphometric characters are coded under the frequency parsimony and gap‐weighting methods, respectively, and the accuracy of these methods is tested. When both types of characters are included, the resulting tree topology is more similar to the topologies obtained from analyses of DNA sequence data than those topologies obtained after exclusion of one or both types of characters. The phylogenetic hypotheses inferred including 59 species of Stenocercus (dataset 1) and excluding those species for which DNA data were not available (dataset 2) are generally congruent with each other, as well as with previously published hypotheses. The most parsimonious tree obtained from analysis of dataset 2 is used in a dispersal‐vicariance analysis to infer ancestral areas and major biogeographical events. Species of Stenocercus are divided into two major clades. Clade A has diversified mostly in the central Andes, with a few species in the northern Andes and one species in the southern Andes. Clade B is more widespread, with species in the northern, central, and southern Andes, as well as in the Atlantic lowlands and Amazon basin. The most recent common ancestor of Stenocercus is inferred to have occurred in the eastern cordillera of the central Andes. Given morphological similarity and altitudinal distribution of some species nested in a northern‐Andes clade, as well as the relatively recent uplift of this Andean region, it is possible that species in this clade have diverged as recently as the mid‐Pliocene.

A TAXONOMIC REVISION OF SOUTH AMERICAN STENOCERCUS (SQUAMATA: IGUANIA) LIZARDS

Abstract South American Stenocercus lizards occur mostly in the Andes and adjacent lowland areas from northern Colombia and Venezuela to central Argentina at elevations of 0–4000 m. In this paper, 61 species of Stenocercus are recognized, including one resurrected as S. angulifer. Morphologically, S. angulifer more closely resembles S. aculeatus. For each species, a diagnosis, description, and summary of distribution are provided based on examination of 2001 specimens and data from the literature. Notes on color in life and natural history are included for most species. Additionally, a dichotomous key to assist in the identification of specimens is provided.

Phylogenetic relationships of South American lizards of the genus Stenocercus (Squamata: Iguania): A new approach using a general mixture model for gene sequence data

The South American iguanian lizard genus Stenocercus includes 54 species occurring mostly in the Andes and adjacent lowland areas from northern Venezuela and Colombia to central Argentina at elevations of 0–4000 m. Small taxon or character sampling has characterized all phylogenetic analyses of Stenocercus, which has long been recognized as sister taxon to the Tropidurus Group. In this study, we use mtDNA sequence data to perform phylogenetic analyses that include 32 species of Stenocercus and 12 outgroup taxa. Monophyly of this genus is strongly supported by maximum parsimony and Bayesian analyses. Evolutionary relationships within Stenocercus are further analyzed with a Bayesian implementation of a general mixture model, which accommodates variability in the pattern of evolution across sites. These analyses indicate a basal split of Stenocercus into two clades, one of which receives very strong statistical support. In addition, we test previous hypotheses using non-parametric and parametric statistical methods, and provide a phylogenetic classification for Stenocercus.

Sedimentary record of Pleistocene and Holocene marine inundations along the North Sea coast of Lower Saxony, Germany

A compilation of geological data about the spatial extent, amplitudes, and dynamics of marine transgressions in the southern North Sea basin and adjacent lowland areas during warm stages of the Pleistocene is used for comparison with the coastal evolution during the final phase of the Weichselian Late Glacial and Holocene and which created the present-day landscape of barrier islands, tidal flats and coastal marshland. The fragmentary sedimentary record left by the repeated transgressions provides evidence that sea-level rise is the dominant factor affecting sediment accumulation in the shallow marine environment and the coastal zone. Although the sea-level rise affected the adjacent lowland areas similarly, it generated complex interactions with the relief of the inundated landscape, and the local hydrological conditions. Especially, the rate of sea-level rise plays a significant role. Whereas a rapidly rising sea level forms monotonous sedimentary sequences, a slowly rising sea level creates a great variety of sedimentary sequences, which show distinct lithological differences over relatively short distances along the coast. These differences are displayed in complex sequences of allochthonous clastic sediments characteristic of tidal flat, brackish-lagoonal, and alluvial environments, as well as intercalated layers of autochthonous fen peat and raised bog peat. Comparison of geological data on the sea-level rise with data obtained from tide gauge records over the last 130 years can be used to place the present-day conditions in the long-term cycle of Quaternary landscape evolution. In addition, it provides a basis for predictions of the future development of the coastal zone.

The record of climatic change in the geological archives of shallow marine, coastal, and adjacent lowland areas of Northern Germany

The record of climatic change in shallow marine, coastal, and adjacent lowland areas has been investigated by three different approaches. A mass balance study focused on the interaction between sea-level rise and Holocene sediment accumulation in the coastal lowland area between the Ems and Weser rivers on the German North Sea coast. This region, which comprises various sedimentary environments, such as barrier islands, sheltered and open tidal flats, bay flats, and estuaries, is highly suitable for such quantitative studies, which can be used to create a model for general mass transport and accumulation processes connected with transgressions over coastal lowlands.An integrated geochemical and microfacies study was made to assess the response of shallow marine, intertidal, and limnic-semiterrestrial environments to the climate-controlled Holocene sea-level rise. The factors controlling the development of various palaeoenvironments were estimated from the distribution of biomarkers, major and trace elements, diatoms, foraminifera and sedimentary structures observed at high resolution in core sections. These data complement those of conventional geological, lithostratigraphical, archaeological and geobotanical investigations.The extensive raised bogs which occur in the Pleistocene hinterland, adjacent to the coastal zone, provided an excellent opportunity to examine peat formation in response to climatic changes in the past. On the basis of a large number of 14C-age determinations special attention was paid to the onset and regional expansion of raised bogs in this region and to the question of whether or not the formation of raised bog peat started synchronously in one or in a series of different phases.

Patterns of Species Composition and Endemism in the Northern Neotropics: A Case for Conservation of Montane Avifaunas

A review of the composition of five montane avifaunas in northwestern South America and southern Central America confirmed the distinctness of these com- munities from adjacent lowland areas. Excluding species that depend on aquatic re- sources, 1,800 bird species from 52 families were classified according to principal life zones in this review. There were 1,366 species associated with lowland areas, whereas 877 species occurred in montane areas (i.e., generally above 1,200 or 1,500 m elevation). Nearly one-half of these montane species are restricted to these high elevations, with the greatest diversity found within subtropical zones, followed by temperate and pr eight families were more species-rich and seven families less spe- cies-rich in montane areas than expected. Moreover, montane areas had a greater number and percentage of species with restricted ranges than did lowland areas. Overall, 217 montane species (24.7%) had small geographic ranges; 142 of these were restricted to one of the five montane regions reviewed here. As evidence of the endangerment of these montane communities, nearly 10% (82) of the species are listed as threatened or near-threatened. Montane habitats are under extreme pressure from human activities. Most urban centers are located in or close to the mountains in the regions reviewed here. Given the high diversity and singularity of these avifaunas, together with high levels of habitat alteration, protection of montane ecosystems should become a priority for con- servation efforts in the Neotropics.

Winter pelage colour in snowshoe hares (Lepus americanus) from the Pacific Northwest

Winter pelage colour was assessed in 207 museum study skins from California, Oregon, Washington, and southwestern British Columbia. Specimens were classified into two distinct colour morphs: brown or white. The brown morph inhabits the coastal lowlands and the Olympic Mountains; the white morph occupies the Sierra Nevada, Blue Mountains, northeastern Washington, and the interior of British Columbia. Except for the occurrences of the brown morph above the snow line in the Olympic Mountains, this distribution correlates with the presence or absence of continuous snow cover and reflects selection for cryptic colouration. The absence of the white morph from areas in the Olympics with snow cover may be the result of intense selection for brown hares in adjacent lowland areas coupled with gene flow or historical biogeographic factors in the Pacific Northwest. Both morphs occur in the Cascade Mountains and coexist at some localities. However, data are insufficient to evaluate the ecological distribution of brown and white hares in the Cascades.