The Use of Ecological Tolerances for the Reconstruction of Tertiary Palaeoclimates

1997 ◽  
Vol 45 (3) ◽  
pp. 475 ◽  
Author(s):  
Helene A. Martin
Keyword(s):  
Vegetation Types ◽  
Climatic Parameters ◽  
Salt Tolerant ◽  
Pollen Assemblage ◽  
Pollen Types ◽  
Living Species ◽  
Marine Influence ◽  
Lagarostrobos Franklinii ◽  
Single Living ◽  
Very High

The major vegetation types may be recognised from the pollen assemblage being deposited beneath them, hence the palaeovegetation may be reconstructed from fossil pollen assemblages. The climatic parameters of the vegetation may then be used to reconstruct palaeoclimates. The result, however, is very general. Most pollen types can only be affiliated with a family, a genus or a group of species and the ecological tolerances within these groups may not be uniform. There are, however, some distinctive pollen types that can be identified with a single living species and this paper examines the potential of these types in the reconstruction of palaeoclimates. Lagarostrobos franklinii (J.D.Hook) Quinn, Huon pine, has a long history and the fossil occurrences of it are compatible with the hypothesis that its ecological tolerances have not changed and it has always required very high humidity. Two sclerophyllous taxa,Eucalyptus spathulata Hook. and Dodonaea triquetra Wendl., however, coexisted with rainforest and then other vegetation types as the climate became drier, adapting to the prevailing conditions. The evidence suggests that the salt-tolerant E. spathulata may have evolved in small patches of coastal scrub, subjected to marine influence, within the dominant rainforest vegetation.

XIX.—Photochemical Measurements of Light Intensity in Two Common Vegetation Types in Tropical Africa, by Means of the Improved Eder-Hecht Photometer

1932 ◽  
Vol 51 ◽  
pp. 150-161 ◽  
Author(s):  
John Phillips ◽  
J. D. Scott ◽  
J. Y. Moggridge
Keyword(s):  
Light Intensity ◽  
Ultraviolet Rays ◽  
Portable Instrument ◽  
Vegetation Types ◽  
Tropical Africa ◽  
Central Plateau ◽  
Positive Correlation ◽  
The Hours ◽  
In Virtue Of ◽  
Very High

Summary(1) A year's measurement of the light-intensity in an exposed site (“mbuga”) and in a Berlinia woodland community, Kikori (4° 21' S.), Tanganyika, by means of the Eder-Hecht Graukeilphotometer is described.(2) The Bunsen-Roscoe units per second are shown to be very high, even under canopy of the Berlinia; they are very much greater than measurements recorded by Dorno for Assuan and Rio de Janeiro.(3) While there is a positive correlation between the B.-R. values and the hours of direct sunshine, it is also clear that during cloudy periods (less than 50 per cent, of possible sunshine is experienced at Kikori and on the Central Plateau of East Africa generally) the B.-R. values are also very high.(4) There is a positive correlation between the values of the Eder-Hecht photometer (in terms of blue-violet-ultraviolet rays), and the readings of the Livingston radio-atmometer measuring the total light-intensity of the same stations in terms of cubic centimetres of water.(5) In virtue of the peculiar effects of the light of Tropical Africa upon the European nervous system, it is urged that quantitative and qualitative studies of the light in those regions should be investigated.(6) Field biologists should make greater use of this efficient, cheap, simple, and portable instrument.

scholarly journals The Tale of a Disappearing Lagoon: A Habitat Mapping and Ecological Assessment of Fosu Lagoon, Ghana

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Bernard Essel ◽  
Justice Kwame Gyesi ◽  
Richmond Kofi Addo ◽  
Wisdom Galley ◽  
Gideon MacCarthy
Keyword(s):  
Vegetation Cover ◽  
Current Trend ◽  
Ecological Assessment ◽  
Remote Sensing And Gis ◽  
Vegetation Types ◽  
Marsh Vegetation ◽  
Gis Technique ◽  
If Current ◽  
Gradual Disappearance ◽  
Very High

Coastal regions of Ghana are primarily engaged in sea and lagoon fishing. Like many lagoons in Ghana, Fosu lagoon is a major source of livelihood for its surrounding communities. However, the lagoon and its associated marsh vegetation is under serious threat from human-induced interference. Due to this, the lagoon is considered as one of the most polluted lagoons in Ghana. Also, studies reveal that a major conservation challenge is the lack of inventory for the lagoon’s associated vegetation. Hence, the research was to map and assess the lagoon’s habitat and identify threats to the lagoon. In achieving the research objectives, remote sensing and GIS technique were used to effectively map the lagoon and the catchment area. The result indicated that the Fosu lagoon is characterized by a massive decline in lagoon size and the vegetation cover. Thus, the standing water has declined by 50.2 acres from 1970 to 2017 to physical development and weeds. Also, it was evident in the result that the lagoon’s vegetation is now fragmented into six various vegetation types and the weeds in the lagoon make approximately one-third of the lagoon’s vegetation cover. Also, adding to the threat of the lagoon were high levels of plastic waste and metal pollution. Hence, if current trend continues, the possibility of further degradation is very high. The main impact of this research was to provide evidence to the gradual disappearance of the Fosu lagoon.

Human Evolution

1984 ◽  
Vol 8 ◽  
pp. 182-198
Author(s):  
Catherine Badgley
Keyword(s):  
Human Evolution ◽  
Evolutionary History ◽  
Pan Paniscus ◽  
Homo Sapiens ◽  
Great Apes ◽  
Sister Group ◽  
The Family ◽  
History Of ◽  
Living Species ◽  
Single Living

The evolutionary history of humans is well understood in outline, compared to that of many other groups of mammals. But human evolution remains enigmatic in its details, and these are compelling both scientifically and personally because they relate to the biological uniqueness of humans. Humans are placed in the primate family Hominidae, which, in traditional classifications, contains a single living species, Homo sapiens. The closest living relatives of humans are great apes: the chimpanzees Pan paniscus and Pan troglodytes, the gorilla Gorilla gorilla, and the orangutan Pongo pygmaeus. These apes have traditionally been placed in the family Pongidae as the sister group of Hominidae. Living Hominidae and Pongidae, together with Hylobatidae (gibbons) comprise the modern representatives of the primate suborder Hominoidea.

Some dicotyledonous pollen types from Cainozoic deposits in the Australian region

1954 ◽  
Vol 2 (2) ◽  
pp. 197
Author(s):  
IC Cookson ◽  
KM Pike
Keyword(s):  
Pollen Grains ◽  
Australian Region ◽  
Pollen Types ◽  
Living Species

Pollen types referable to the families Casuarinaceae, Haloragaceae,Myrtaceae, Olacaceae, Proteaceae, Santaiaceae, and Sapindaceae have been described from Cainozoic deposits in the Australian region; their relationship to living species has been discussed wherever possible. The characters and distribution of three sporomorphs of uncertain affinity have been considered. Details concerning the pollen grains of some of the living species of Anacolosa, Cathedra, Casuarina, the tribe Cupanieae (Sapindaceae), Haloragis, Myriophyllurn, and Santalurn have been recorded.

scholarly journals A Sixteen Thousand Year Old Organic Deposit, Northern Baffin Island, N.W.T., Canada: Palynology and Significance

2007 ◽  
Vol 42 (1) ◽  
pp. 75-82 ◽  
Author(s):  
Susan K. Short ◽  
John T. Andrews
Keyword(s):  
Baffin Island ◽  
Pollen Assemblage ◽  
Radiocarbon Dates ◽  
Pollen Types ◽  
Rapid Accumulation ◽  
Terrestrial Sediments ◽  
Organic Deposit

ABSTRACT A 3 m exposure of sediment containing organics was sampled near the settlement of Arctic Bay, Baffin Island, N.W.T. A total of seven radiocarbon dates have been obtained from the deposit. Three dates between 182.5 and 290 cm depth gave radiocarbon ages between 14,185 ± 760 and 16,849 ± 860. A date from 82.5 to 87.5 cm resulted in an age of 8635 ± 565. An apparent reversal in 14C dates may reflect folding of the sediments associated with the downslope creep of the deposit or rapid accumulation of organics. The three basal dates are the first terrestrial sediments from Baffin Island to date from older than ca. 10,000 BP and less than 20,000 BP. Analysis of the sediment for pollen indicated that it is generally sparse. The pollen assemblage is dominated by Salix, Cyperaceae, and Gramineae pollen and exotic pollen types {Pinus, Picea, Betula, and Alnus) occur sporadically throughout the section.

scholarly journals A Miocene pygmy right whale fossil from Australia

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5025 ◽  
Author(s):  
Felix G. Marx ◽  
Travis Park ◽  
Erich M.G. Fitzgerald ◽  
Alistair R. Evans
Keyword(s):  
Southern Hemisphere ◽  
Late Miocene ◽  
External Morphology ◽  
Baleen Whales ◽  
Right Whale ◽  
Right Whales ◽  
Molecular Divergence ◽  
Living Species ◽  
Divergence Estimates ◽  
Single Living

Neobalaenines are an enigmatic group of baleen whales represented today by a single living species: the pygmy right whale, Caperea marginata, found only in the Southern Hemisphere. Molecular divergence estimates date the origin of pygmy right whales to 22–26 Ma, yet so far there are only three confirmed fossil occurrences. Here, we describe an isolated periotic from the latest Miocene of Victoria (Australia). The new fossil shows all the hallmarks of Caperea, making it the second-oldest described neobalaenine, and the oldest record of the genus. Overall, the new specimen resembles C. marginata in its external morphology and details of the cochlea, but is more archaic in it having a hypertrophied suprameatal area and a greater number of cochlear turns. The presence of Caperea in Australian waters during the Late Miocene matches the distribution of the living species, and supports a southern origin for pygmy right whales.

scholarly journals Harnessing the Power of Metabarcoding in the Ecological Interpretation of Plant—Pollinator DNA Data: Strategies and Consequences of Filtering Approaches

Diversity ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 437
Author(s):  
Nicola Tommasi ◽  
Andrea Ferrari ◽  
Massimo Labra ◽  
Andrea Galimberti ◽  
Paolo Biella
Keyword(s):  
Species Richness ◽  
High Sensitivity ◽  
Conservative Approach ◽  
Pollen Assemblage ◽  
Future Studies ◽  
Molecular Features ◽  
Dna Metabarcoding ◽  
Plant Pollinator ◽  
Very High ◽  
Do So

Although DNA metabarcoding of pollen mixtures has been increasingly used in the field of pollination biology, methodological and interpretation issues arise due to its high sensitivity. Filtering or maintaining false positives, contaminants, and rare taxa or molecular features could lead to different ecological results. Here, we reviewed how this choice has been addressed in 43 studies featuring pollen DNA metabarcoding, which highlighted a very high heterogeneity of filtering methods. We assessed how these strategies shaped pollen assemblage composition, species richness, and interaction networks. To do so, we compared four processing methods: unfiltering, filtering with a proportional 1% of sample reads, a fixed threshold of 100 reads, and the ROC approach (Receiver Operator Characteristic). The results indicated that filtering impacted species composition and reduced species richness, with ROC emerging as a conservative approach. Moreover, in contrast to unfiltered networks, filtering decreased network Connectance and Entropy, and it increased Modularity and Connectivity, indicating that using cut-off thresholds better describes interactions. Overall, unfiltering might compromise reliable ecological interpretations, unless a study targets rare species. We discuss the suitability of each filtering type,plead for justifying filtering strategies on biological or methodological bases and for developing shared approaches to make future studies more comparable.

Holocene pollen assemblages from the Tiger Hills, Manitoba

1968 ◽  
Vol 5 (4) ◽  
pp. 873-880 ◽  
Author(s):  
J. C. Ritchie ◽  
Sigrid Lichti-Federovich
Keyword(s):  
Deciduous Forest ◽  
Pollen Assemblage ◽  
The Holocene ◽  
Radiocarbon Age ◽  
Arboreal Pollen ◽  
Pollen Types ◽  
Weedy Species ◽  
Zone Ii ◽  
Shepherdia Canadensis ◽  
Age Determinations

Coring of three kettle lakes in the moraine area known as the Tiger Hills, Manitoba, yielded sections of sediment which span the Holocene for this region. Detailed pollen analysis of two of the sections suggests five main pollen assemblage zones for the Holocene, numbered I to V from above. Zone V is interpreted as a spruce-dominated vegetation associated with such pioneering species as Shepherdia canadensis and Artemisia, a type found at present as local fragments and having no regional equivalent. Zone IV also has no analogue among recent pollen spectra, and is interpreted as a mosaic of mixed coniferous–broadleaved deciduous forest stands, and extensive scrub with Juniperus and grassland. Zone III is dominated by non-arboreal pollen types and suggests grassland, while Zone II has an oak component, which indicates a savanna type. Zone I is the modern assemblage, with prominent representation by weedy species. Radiocarbon age determinations suggest that the area was occupied by the Zone V assemblage from about 12 800 B.P.

Life sciences - Terrestrial ecosystems in the Antarctic

1977 ◽  
Vol 279 (963) ◽  
pp. 5-25 ◽  
Keyword(s):  
Antarctic Peninsula ◽  
Ecological Systems ◽  
East Antarctica ◽  
South Shetland Islands ◽  
Vegetation Types ◽  
Maritime Antarctic ◽  
Mcmurdo Sound ◽  
Signy Island ◽  
The Antarctic ◽  
Very High

The composition of the terrestrial Antarctic flora and fauna and the distribution patterns of a number of species and of the principal vegetation types is now reasonably well established, at least in outline, for the Antarctic Peninsula region and the areas about McMurdo Sound as well as for some areas around the coastal ranges of East Antarctica. Detailed research at Signy Island has provided information concerning the biomass and productivity of certain vegetation types, decomposer organisms, microbivores, and invertebrate herbivores and predators. The main pathways of energy and nutrient within the terrestrial study sites can be regarded as reasonably established. Net annual production locally reaches very high levels (up to 800 g m -2 ). Only a tiny part of this productivity is consumed by herbivores, the greater part passing to the decomposers or persisting as peat. Most of the animals are microbivores, or graze on fungi, and in turn sustain the small number of invertebrate predators. Analysis of the range of habitats even on Signy Island indicates however that the sites for which detailed ecological information is available represent only a part of the range of environmental and ecological variation. The island is in fact characterized by a very high level of within-site diversity, some of it on a very small scale. Similarly, recent research which permits ecological comparisons with the sub-Antarctic islands of South Georgia and Macquarie, and with the McMurdo area, confirms that Signy Island displays only a small part of the very large range of diversity within the Antarctic regions as a whole. It is a reasonably representative sample of the maritime Antarctic zone in the Antarctic Peninsula region where conditions are particularly favourable for terrestrial life. Its ecological features resemble most closely those of the South Shetland Islands (except over permeable volcanic rocks) and the Palmer Archipelago on the western side of the Antarctic Peninsula. Very different plant and animal communities occur over much of the McMurdo Sound region and in the inland ranges of East Antarctica. Some general statements can now be made about the relationships between terrestrial Antarctic eco-systems and climatic, edaphic and historical factors. There is a clearly marked attenuation of the vegetation and fauna and simplification of the ecological systems as one moves towards cold, arid continental conditions. But the biota of the maritime Antarctic and the sub-Antarctic islands is more impoverished than ecological factors alone would indicate, because of the isolation of these land habitats, many of which have only recently been deglaciated. If present environmental conditions persist, a slow increase in the complexity of these ecological systems is to be expected and in some areas, especially the subantarctic islands, this process is being accelerated by human influence.

scholarly journals Variability of pollen aperture heteromorphism in annual pansies (Viola Section Melanium)

2015 ◽  
Vol 74 (1) ◽  
pp. 43-52 ◽  
Author(s):  
Sara Magrini ◽  
Anna Scoppola
Keyword(s):  
Pollen Grains ◽  
Perennial Species ◽  
Pollen Assemblage ◽  
Significant Variability ◽  
Pollen Types ◽  
Pollen Heteromorphism

Abstract Pollen heteromorphism is frequent in the section Melanium of the genus Viola, in which over 80% of the species produces pollen morphs with 3 to 6 apertures. Some authors have pointed out that many factors can affect the proportion of the different pollen types in perennial species, and that this proportion can change among populations. This work focuses on the study of the polymorphic pollen assemblage of three annual pansies: Viola arvensis, V. kitaibeliana, and V. hymettia, and on the assessment of its variability both within a population and within the same plant. In all the species, with both large and small flowers, 3-, 4- and 5-aperturate pollen grains were observed, with a large prevalence of 4-aperturate types. No pollen grains with 6 apertures were found. No significant variability of the pollen assemblage among flowers of the same plant was observed. In addition, in these three Viola species the frequencies of the various pollen morphs are also fairly constant among plants of the same population.

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