Here we developed a composite pollen-based record of altitudinal vegetation changes from Lake Fúquene (5° N) in Colombia at 2540 m elevation. We quantitatively calibrated Arboreal Pollen percentages ...(AP%) into mean annual temperature (MAT) changes with an unprecedented ~60-year resolution over the past 284 000 years. An age model for the AP% record was constructed using frequency analysis in the depth domain and tuning of the distinct obliquity-related variations to the latest marine oxygen isotope stacked record. The reconstructed MAT record largely concurs with the ~100 and 41-kyr (obliquity) paced glacial cycles and is superimposed by extreme changes of up to 7 to 10° Celsius within a few hundred years at the major glacial terminations and during marine isotope stage 3, suggesting an unprecedented North Atlantic – equatorial link. Using intermediate complexity transient climate modelling experiments, we demonstrate that ice volume and greenhouse gasses are the major forcing agents causing the orbital-related MAT changes, while direct precession-induced insolation changes had no significant impact on the high mountain vegetation during the last two glacial cycles.
Amazonian waters are classified into three biogeochemical categories by dissolved nutrient content, sediment type, transparency, and acidity-all important predictors of autochthonous and ...allochthonous primary production (PP): (1) nutrient-poor, low-sediment, high-transparency, humic-stained, acidic blackwaters; (2) nutrient-poor, low-sediment, high-transparency, neutral clearwaters; (3) nutrient-rich, low-transparency, alluvial sediment-laden, neutral whitewaters. The classification, first proposed by Alfred Russel Wallace in 1853, is well supported but its effects on fish are poorly understood. To investigate how Amazonian fish community composition and species richness are influenced by water type, we conducted quantitative year-round sampling of floodplain lake and river-margin habitats at a locality where all three water types co-occur. We sampled 22,398 fish from 310 species. Community composition was influenced more by water type than habitat. Whitewater communities were distinct from those of blackwaters and clearwaters, with community structure correlated strongly to conductivity and turbidity. Mean per-sampling event species richness and biomass were significantly higher in nutrient-rich whitewater floodplain lakes than in oligotrophic blackwater and clearwater river-floodplain systems and light-limited whitewater rivers. Our study provides novel insights into the influences of biogeochemical water type and ecosystem productivity on Earth's most diverse aquatic vertebrate fauna and highlights the importance of including multiple water types in conservation planning.
This paper compares a new super-high resolution pollen record from a central location in Lake Fúquene (4°N) with 3 pollen records from marginal sites from the same lake basin, located at 2540 m ...elevation in the Eastern Cordillera of Colombia. We harmonized the pollen sum of all records, and provided previously published records of climate change with an improved age model using a new approach for long continental pollen records. We dissociated from subjective curve matching and applied a more objective procedure including radiocarbon ages, cyclostratigraphy, and orbital tuning using the new 284 ka long Fúquene Basin Composite record (Fq-BC) as the backbone (
Groot et al., 2011). We showed that a common ∼9 m cycle in the arboreal pollen percentage (AP%) records reflects obliquity forcing and drives vegetational and climatic change. The AP% records were tuned to the 41 kyr component filtered from standard benthic δ
18O LR04 record. Changes in sediment supply to the lake are reflected in concert by the four records making frequency analysis in the depth domain an adequate method to compare records from the same basin. We calibrated the original
14C ages and used where necessary biostratigraphic correlation, i.e. for records shorter than one obliquity cycle. Pollen records from the periphery of the lake showed changes in the abundance of
Alnus and
Weinmannia forests more clearly while centrally located record Fq-9C shows a more integrated signal of regional vegetation change.
The revised age models show that core Fq-2 reflects the last 44 ka and composite record Fq-7C the last 85.5 ka. Marginally located core Fq-3 has an age of 133 ka at 32 m core depth and the lowermost 11 m of sediments appear of older but unknown age. The longest record Fq-BC shows ∼60 yr resolution over the period of 284-27 ka. All pollen records are in support of a common regional vegetation development leading to a robust reconstruction of long series of submillennial climate oscillations reflecting Dansgaard–Oeschger (DO) cycles. Reconstructed climate variability in the tropical Andes since marine isotope stage (MIS) 8 compares well with NGRIP (δ
18O based), Epica Dome C (δD based) and the Mediterranean sea surface temperature record MD01-2443/44 (U
K′37 based) underpinning the global significance of the climate record from this tropical Andean lake. A basin-wide biostratigraphy is presented and we concluded although with varying robustness that each core is representative of regional vegetational and climatic change.
► Four climate sensitive pollen records from a tropical North Andean lake were compared. ►
14C ages, cyclostratigraphy and orbital tuning show 284 ka with 60 yr resolution. ► Migrating altitudinal vegetation distributions show submillennial–scale cycles. ► Over/under-representation of pollen at marginal/central lake sites is shown. ► DO cycles during MIS 2-8 in land, sea and ice cores show a robust climate correlation.
We present a record of environmental and climatic changes in the northern Andes during the penultimate interglacial-glacial cycle based on integrated information from pollen and grain size ...distributions (GSDs). The record reflects the 58.33-26.21 m interval of a new sediment core from Lake Fuquene (2540 m elevation; 5 degree N) in the Colombian Andes. The age model is mainly based on cyclostyratigraphy and shows that this core interval reflects the period from 284 to 130 ka. The 1 cm sample increments yield a resolution of ~ 60 yr. In 2553 samples we analyzed 66 selected pollen and spore taxa with the best known ecological ranges. We reconstructed upper forest line (UFL) positions between ~ 2000 and ~ 3400 m elevation and the most abrupt temperature shifts ranged up to 10 degree C/100 yr at Terminations II and III. Regional vegetation change is mainly driven by eccentricity (100 kyr) and obliquity (41 kyr) cycles, while changes in local aquatic vegetation show variability in the obliquity and precession (21 kyr) bands. Millennial-scale climate variability reflecting Dansgaard-Oeschger (DO) climate cycles in the upper part of the record, continues in this penultimate intergalcial-glacial cycle strongly suggesting that this variability has a persistent character in Pleistocene vegetation and climate dynamics. Short-lived upslope excursions of the UFL reflect 20 DO-style cycles during marine isotope stages (MIS) 7 and 6. Changes in species composition of montane forest are evident, and trees with most pioneer qualities (Alnus, Morella, Quercus and Weinmannia) migrated at the forefront. Other arboreal taxa like Podocarpus, Miconia, and Hedyosmum mostly followed later. Changes in regional vegetation distribution and forest composition, as well as in local aquatic vegetation and GSD of sediments supplied to the lake, allowed the development of an integrated reconstruction of the biotic and abiotic environments in the drainage basin.
Abstract
The transition from a greenhouse to an icehouse world at the Eocene-Oligocene Transition (EOT) coincided with a large decrease of pollen from the steppe-adapted genus Nitraria. This genus, ...now common along the Mediterranean coast, Asia and Australia, has a proposed coastal origin and a geographically widespread fossil record. Here we investigated the evolution, taxonomic diversity and morphological disparity of Nitraria throughout the Cenozoic by integrating extant taxa and fossil palynological morphotypes into a unified phylogenetic framework based on both DNA sequences and pollen morphological data. We present the oldest fossil pollen grain of Nitraria, at least 53 Myr old. This fossil was found in Central Asian deposits, providing new evidence for its origin in this area. We found that the EOT is an evolutionary bottleneck for Nitraria, coinciding with retreat of the proto-Paratethys Sea, a major global cooling event and a turnover in Central Asian steppe vegetation. We infer the crown age of modern Nitraria spp. to be significantly younger (Miocene) than previously estimated (Palaeocene). The diversity trajectory of Nitraria inferred from extant-only taxa differs markedly from one that also considers extinct taxa. Our study demonstrates it is therefore critical to apply an integrative approach to fully understand the plant evolutionary history of Nitrariaceae.
is a halophytic taxon (i.e., adapted to saline environments) that belongs to the plant family Nitrariaceae and is distributed from the Mediterranean, across Asia into the south-eastern tip of ...Australia. This taxon is thought to have originated in Asia during the Paleogene (66-23 Ma), alongside the proto-Paratethys epicontinental sea. The evolutionary history of
might hold important clues on the links between climatic and biotic evolution but limited taxonomic documentation of this taxon has thus far hindered this line of research. Here we investigate if the pollen morphology and the chemical composition of the pollen wall are informative of the evolutionary history of
and could explain if origination along the proto-Paratethys and dispersal to the Tibetan Plateau was simultaneous or a secondary process. To answer these questions, we applied a novel approach consisting of a combination of Fourier Transform Infrared spectroscopy (FTIR), to determine the chemical composition of the pollen wall, and pollen morphological analyses using Light Microscopy (LM) and Scanning Electron Microscopy (SEM). We analysed our data using ordinations (principal components analysis and non-metric multidimensional scaling), and directly mapped it on the Nitrariaceae phylogeny to produce a phylomorphospace and a phylochemospace. Our LM, SEM and FTIR analyses show clear morphological and chemical differences between the sister groups
and
. Differences in the morphological and chemical characteristics of highland species (
and
and lowland species (
and
are very subtle, with phylogenetic history appearing to be a more important control on
pollen than local environmental conditions. Our approach shows a compelling consistency between the chemical and morphological characteristics of the eight studied Nitrariaceae species, and these traits are in agreement with the phylogenetic tree. Taken together, this demonstrates how novel methods for studying fossil pollen can facilitate the evolutionary investigation of living and extinct taxa, and the environments they represent.
We present a record of environmental and climatic changes in the northern Andes during the penultimate interglacial–glacial cycle based on integrated information from pollen and grain size ...distributions (GSDs). The record reflects the 58.33–26.21m interval of a new sediment core from Lake Fúquene (2540m elevation; 5°N) in the Colombian Andes. The age model is mainly based on cyclostyratigraphy and shows that this core interval reflects the period from 284 to 130ka. The 1cm sample increments yield a resolution of ~60yr. In 2553 samples we analyzed 66 selected pollen and spore taxa with the best known ecological ranges. We reconstructed upper forest line (UFL) positions between ~2000 and ~3400m elevation and the most abrupt temperature shifts ranged up to 10°C/100yr at Terminations II and III. Regional vegetation change is mainly driven by eccentricity (100kyr) and obliquity (41kyr) cycles, while changes in local aquatic vegetation show variability in the obliquity and precession (21kyr) bands. Millennial-scale climate variability reflecting Dansgaard–Oeschger (DO) climate cycles in the upper part of the record, continues in this penultimate intergalcial–glacial cycle strongly suggesting that this variability has a persistent character in Pleistocene vegetation and climate dynamics. Short-lived upslope excursions of the UFL reflect 20 DO-style cycles during marine isotope stages (MIS) 7 and 6. Changes in species composition of montane forest are evident, and trees with most pioneer qualities (Alnus, Morella, Quercus and Weinmannia) migrated at the forefront. Other arboreal taxa like Podocarpus, Miconia, and Hedyosmum mostly followed later. Changes in regional vegetation distribution and forest composition, as well as in local aquatic vegetation and GSD of sediments supplied to the lake, allowed the development of an integrated reconstruction of the biotic and abiotic environments in the drainage basin.
•We show pollen-based climate change at 60-yr resolution during 284–130ka (MIS 7–6) in the northern Andes.•DO-style cycles since MIS 8 suggest that ~2.7kyr climate variability has a permanent character in Pleistocene climate.•We show a water level record based on 4 categories aquatics and 5 grain size classes.•Pioneer and late-successional trees potentially cause temporary no-analog vegetation.
In a ~60 m long record reflecting the period from 284 ka to 27 ka we analysed grain size distributions (GSD), organic carbon content, and aquatic pollen assemblages at 1-cm increments. The ...4768-points time series show with ~60 yr resolution the dynamic history of Lake Fúquene (2540 m alt., 4° N lat.) of the northern Andes during two full interglacial-glacial cycles. GSD show proportions of clay, fine silt, coarse silt, and sand evidencing the location of the sediment source (proximal vs distal) in relation to the drilling site, and available energy to transport sediments in the catchment area. Loss-on-ignition (LOI) values reflect estimates of the abundance of organic matter (OM) in the sediments. Aquatic pollen were grouped into assemblages characteristic of deep water, shallow water, swamp, and wet lake shore environments, reflecting a hydrological gradient sensitive for lake level changes. The End-Member Modelling Algorithm (EMMA) showed that 4 end-members (EMs) explain an optimal proportion (70%) of the observed variation. EMMA is able to unmix GSD of lacustrine sediments in a genetically meaningful way allowing EMs to be interpreted in past depositional and environmental settings. Most unexplained variability is located in the fraction of coarse sediment. OM content was estimated on the basis of LOI data and formed a fifth EM that mainly indicates presence of peat. Changes concur with submillennial-scale variability established in other proxies from this record (Groot et al., 2011). Periods with distinct sediment compositions are 284-243 ka (mainly MIS 8), 243-201 ka (mainly MIS 7), 201-179 ka (mainly MIS 7/6 transition), 179-133 ka (mainly MIS 6), 133-111 ka, (mainly MIS 5e) 111-87 ka (mainly MIS 5d-5b), 87-79 ka (mainly MIS 5a), 79-62 ka (mainly MIS 4), and 62-27 ka (MIS 3) showing sedimentological regimes are climate driven.
ABSTRACT
Aim
Forest composition and distribution are determined by a myriad of factors, including climate. As models of tropical rain forest, palms are often used as indicator taxa, particularly the ...Mauritiinae. We question, what characterizes the Mauritiinae pollen in the global fossil record? And when did the Mauritiinae become endemic to South America?
Location
Global tropics.
Taxon
Mauritiinae palms (Arecaceae: Lepidocaryeae).
Methods
Pollen trait data from extinct and extant Mauritiinae pollen were generated from light‐, scanning‐, and transmission electron microscopy. Statistical morphometric analysis was used to define species and their relationships to other Mauritiinae. We also compiled a comprehensive pollen database for extinct and extant Mauritiinae and mapped their global geographical distribution from Late Cretaceous to present, using GBIF and fossil data.
Results
Our morphometric analysis identified 18 species (11 extinct and seven extant), all exhibiting exine indentations, a synapomorphy of the subtribe. The fossil taxa and early divergent extant Lepidocaryum are all monosulcate, whereas the extant Mauritia and Mauritiella species are all monoulcerate. Paleobiogeographical maps of fossil Mauritiinae pollen occurrences suggest the taxon originated in equatorial Africa during the Cretaceous, and expanded their range to South America, and to India in the Paleocene. Range retraction started in the early Eocene with extirpation from India, and reduction in diversity in Africa culminating at the Eocene–Oligocene Transition (EOT). In contrast, in South America, the distribution is maintained, and since the Neogene Mauritiinae palms are mostly restricted to swampy, lowland habitats.
Main conclusions
Morphometric analysis shows that since their origin Mauritiinae pollen are relatively species poor, and Mauritiidites resembles Lepidocaryum. We also conclude that the biogeographical history of the Mauriitinae and, by extension, tropical forests was strongly affected by global climatic cooling events. In particular, the climate change at the EOT was a fundamental determinant of current tropical forest distribution.
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