Pliocene reversal of late Neogene aridification Sniderman, J. M. Kale; Woodhead, Jon D.; Hellstrom, John ...
Proceedings of the National Academy of Sciences - PNAS,
02/2016, Letnik:
113, Številka:
8
Journal Article
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Odprti dostop
The Pliocene epoch (5.3–2.6 Ma) represents the most recent geological interval in which global temperatures were several degrees warmer than today and is therefore considered our best analog for a ...future anthropogenic greenhouse world. However, our understanding of Pliocene climates is limited by poor age control on existing terrestrial climate archives, especially in the Southern Hemisphere, and by persistent disagreement between paleo-data and models concerning the magnitude of regional warming and/or wetting that occurred in response to increased greenhouse forcing. To address these problems, here we document the evolution of Southern Hemisphere hydroclimate from the latest Miocene to the middle Pliocene using radiometrically-dated fossil pollen records preserved in speleothems from semiarid southern Australia. These data reveal an abrupt onset of warm and wet climates early within the Pliocene, driving complete biome turnover. Pliocene warmth thus clearly represents a discrete interval which reversed a long-term trend of late Neogene cooling and aridification, rather than being simply the most recent period of greater-than-modern warmth within a continuously cooling trajectory. These findings demonstrate the importance of high-resolution chronologies to accompany paleoclimate data and also highlight the question of what initiated the sustained interval of Pliocene warmth.
Aim: The mesic biome, encompassing both rain forest and open sclerophyllous forests, is central to understanding the evolution of Australia's terrestrial biota and has long been considered the ...ancestral biome of the continent. Our aims are to review and refine key hypotheses derived from palaeoclimatic data and the fossil record that are critical to understanding the evolution of the Australian mesic biota. We examine predictions arising from these hypotheses using available molecular phylogenetic and phylogeographical data. In doing so, we increase understanding of the mesic biota and highlight data deficiencies and fruitful areas for future research. Location: The mesic biome of Australia, along the eastern coast of Australia, and in the south-east and south-west, including its rain forest and sclerophyllous, often eucalypt-dominated, habitats. Methods: We derived five hypotheses based on palaeoclimatic and fossil data regarding the evolution of the Australian mesic biota, particularly as it relates to the mesic biome. We evaluated predictions formulated from these hypotheses using suitable molecular phylogenies of terrestrial plants and animals and freshwater invertebrates. Results: There was support for the ancestral position of mesic habitat in most clades, with support for rain forest habitat ancestry in some groups, while evidence of ancestry in mesic sclerophyllous habitats was also demonstrated for some plants and herpetofauna. Contraction of mesic habitats has led to extinction of numerous lineages in many clades and this is particularly evident in the rain forest component. Species richness was generally higher in sclerophyllous clades than in rain forest clades, probably due to higher rates of net speciation in the former and extinction in the latter. Although extinction has been prominent in rain forest communities, tropical rain forests appear to have experienced extensive immigration from northern neighbours. Pleistocene climatic oscillations have left genetic signatures at multiple levels of divergence and with complex geographical structuring, even in areas with low topographical relief and few obvious geographical barriers. Main conclusions: Our review confirms long-held views of the ancestral position of the Australian mesic biome but also reveals new insights into the complexity of the processes of contraction, fragmentation, extinction and invasion during the evolution of this biome.
Many species of birds breeding on ocean beaches and in coastal dunes are of global conservation concern. Most of these species rely on invertebrates (e.g. insects, small crustaceans) as an ...irreplaceable food source, foraging primarily around the strandline on the upper beach near the dunes. Sandy beaches are also prime sites for human recreation, which impacts these food resources via negative trampling effects. We quantified acute trampling impacts on assemblages of upper shore invertebrates in a controlled experiment over a range of foot traffic intensities (up to 56 steps per square metre) on a temperate beach in Victoria, Australia. Trampling significantly altered assemblage structure (species composition and density) and was correlated with significant declines in invertebrate abundance and species richness. Trampling effects were strongest for rare species. In heavily trafficked plots the abundance of sand hoppers (Amphipoda), a principal prey item of threatened Hooded Plovers breeding on this beach, was halved. In contrast to the consistently strong effects of trampling, natural habitat attributes (e.g. sediment grain size, compactness) were much less influential predictors. If acute suppression of invertebrates caused by trampling, as demonstrated here, is more widespread on beaches it may constitute a significant threat to endangered vertebrates reliant on these invertebrates. This calls for a re-thinking of conservation actions by considering active management of food resources, possibly through enhancement of wrack or direct augmentation of prey items to breeding territories.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We describe a new species of dung beetle,
Epactoides giganteus
sp. nov.
, from a single female specimen allegedly collected in the 19
th
century on Réunion island and recently found at the Muséum ...national d’Histoire naturelle, Paris. This species differs from other species of
Epactoides
by larger size and a set of other distinctive morphological characters.
Epactoides giganteus
sp. nov.
is the first native dung beetle (Scarabaeinae) of Réunion, and its discovery expands the known area of distribution of the genus
Epactoides
, which was hitherto believed to be endemic to Madagascar. Like other taxa from Madagascar and peripheral islands (e.g., Comoro, Seychelles, Mascarenes),
E. giganteus
sp. nov.
may have reached Réunion by over-water dispersal. Given the rapid loss of biodiversity on Réunion island and the fact that no additional specimens were re-collected over the last two centuries, it is very likely that
E. giganteus
sp. nov.
has gone extinct. However, we have unconfirmed evidence that the holotype of
E. giganteus
sp. nov.
might be a mislabeled specimen from Madagascar, which would refute the presence of native dung beetles on Réunion. We discuss both hypotheses about the specimen origin and assess the systematic position of
E. giganteus
sp. nov.
by examining most of the described species of Madagascan
Epactoides
. Additionally, we provide a brief overview of the dung beetle fauna of Mascarene Archipelago.
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•We reconstruct a well-resolved phylogeny of the major lineages of Trechitae.•The Bembidarenas group of genera form a clade, sister to Trechini.•The geographically isolated genera ...Sinozolus, Chaltenia, and Phrypeus form a clade.•Extensive convergence is revealed in morphological characters.•Shores of running water may be an ancestral habitat for large portions of Trechitae.
Using data from two nuclear ribosomal genes and four nuclear protein-coding genes, we infer a well-resolved phylogeny of major lineages of the carabid beetle supertribe Trechitae, based upon a sampling of 259 species. Patrobini is the sister group of Trechitae, but the genus Lissopogonus appears to be outside of the Patrobini + Trechitae clade. We find that four enigmatic trechite genera from the Southern Hemisphere, Bembidarenas, Argentinatachoides, Andinodontis, and Tasmanitachoides, form a clade that is the sister group of Trechini; we describe this clade as a new tribe, Bembidarenini. Bembidarenini + Trechini form the sister group of remaining trechites. Within Trechini, subtribe Trechodina is not monophyletic, as three trechodine genera from Australia (Trechobembix, Paratrechodes, Cyphotrechodes) are the sister group of subtribe Trechina. Trechini appears to have originated in the continents of the Southern Hemisphere, with almost all Northern Hemisphere lineages representing a single radiation within the subtribe Trechina. We present moderate evidence that the geographically and phylogenetically isolated genera Sinozolus (six species in the mountains of China), Chaltenia (one species in Argentina and Chile), and Phrypeus (one species in western North America) also form a clade, the tribe Sinozolini. The traditionally recognized tribe Bembidiini sens. lat., diagnosed by the presence of a subulate terminal palpomere, is shown to be polyphyletic; subulate palpomeres have arisen five times within Trechitae. Anillini is monophyletic, and the sister group of Tachyini + Pogonini + Bembidiini + Zolini + Sinozolini; within anillines, we confirm earlier results indicating the eyed New Zealand genus Nesamblyops as the sister to the rest. Sampled New World Pogonini are monophyletic, rendering the genus Pogonus non-monophyletic. Tachyina and Xystosomina are sister groups. Within Xystosomina, the New World members are monophyletic, and are sister to an Australia-New Zealand clade. The latter consists of the genus Philipis as well as taxa not previously recognized as xystosomines: Kiwitachys, the “Tachys” ectromioides group, and “Tachys” mulwalensis. Within Tachyina, the subgenus Elaphropus is not closely related to other subgenera previously placed in the genus Elaphropus; we move the other subgenera into the genus Tachyura. Tachyina with a bifoveate mentum do not form a clade; in fact, a bifoveate mentum is found in Xystosomina, Sinozolini, Trechini, Trechitae and its sister group, Patrobini. Extensive homoplasy in the morphological characters previously used as key indicators of relationship is supported by our results: in addition to multiple origins of subulate palpomeres and bifoveate menta, a concave protibial notch has arisen independently in Anillina, Xystosomina, and Tachyina. Phylogenetically and geographically isolated, species-poor lineages in Trechini, Bembidarenini, and Sinozolini may be relicts of more widespread faunas; many of these are found today on gravel or sand shores of creeks and rivers, which may be an ancestral habitat for portions of Trechitae. In addition to the description of Bembidarenini, we present a diagnosis of the newly delimited Sinozolini, and keys to the tribes of Trechitae.
Remote islands harbour many endemic species and unique ecosystems. They are also some of the world's most human-impacted systems. It is essential to understand how island species and ecosystems ...behaved prior to major anthropogenic disruption as a basis for their conservation. This research aims to reconstruct the original, pre-colonial biodiversity of a remote oceanic island to understand the scale of past extinctions, vegetation changes and biodiversity knowledge gaps.
We studied fossil remains from the North Atlantic island of Corvo (Azores), including pollen, charcoal, plant macrofossils, diatoms and geochemistry of wetland sediments from the central crater of the island, Caldeirão. A comprehensive list of current vascular plant species was compiled, along with a translation table comparing fossilized pollen to plant species and a framework for identifying extinctions and misclassifications.
Pollen and macrofossils provide evidence for eight local extinctions from the island's flora and show that four species listed as ‘introduced’ are native. Up to 23 % of the pollen taxa represent extinct/misclassified species. Corvo's past environment was dynamic, shifting from glacial-era open vegetation to various Holocene forest communities, then almost completely deforested by fires, erosion and grazing following Portuguese colonisation. Historical human impacts explain high ecological turnover, several unrecorded extinctions and the present-day abundance of vegetation types like Sphagnum blanket mire.
We use Corvo as a case study on how fossil inventories can address the Wallacean and Hookerian biodiversity knowledge gaps on remote islands. Accurate baselines allow stakeholders to make informed conservation decisions using limited financial and human resources, particularly on islands where profound anthropogenic disruption occurred before comprehensive ecological research.
Display omitted
•Human impacts transformed island vegetation and soils•Evidence for unrecorded extinctions and almost complete forest loss•Framework for determining native/introduced status from fossils•Key baseline information for habitat restoration
One of the most conspicuous features of many moth species is their antennae, which can be strikingly elaborate. However, the factors that have influenced the evolution of these impressive receptor ...organs remain poorly known. Antennae are potentially costly structures, and previous research has indicated that investment in these structures may be traded‐off against investment in other organs, depending on the mating strategy in which individuals engage. Using a phylogenetic comparative analysis of data from dissected wild‐caught individuals from 44 Australian moth species, we examined potential trade‐offs and correlations between antennal size (measured as antenna length and antenna area) and the size of a range of other morphological features related to paternity (testis area), and vision (eye diameter). Antenna area did not show any evidence of a trade‐off with testis size (area) after controlling for body size and phylogeny. Further, relative antenna length was positively correlated with relative eye size, suggesting that investment in both sensory structures is linked. Analysis of the allometric scaling of antennal size and eye diameter found that larger moth species invested relatively more in the size of their male antennae (both area and length) than in the size of their eyes. These results indicate different patterns of investment in sensory structures in relation to body size, with larger moth species favouring the evolution of more elaborate antennae in males.
We describe a new species of dung beetle,
Epactoides
giganteus
sp. nov.
, from a single female specimen allegedly collected in the 19
th
century on Réunion island and recently found at the Muséum ...national d’Histoire naturelle, Paris. This species differs from other species of
Epactoides
by larger size and a set of other distinctive morphological characters.
Epactoides
giganteus
sp. nov.
is the first native dung beetle (
Scarabaeinae
) of Réunion, and its discovery expands the known area of distribution of the genus
Epactoides
, which was hitherto believed to be endemic to Madagascar. Like other taxa from Madagascar and peripheral islands (e.g., Comoro, Seychelles, Mascarenes),
E.
giganteus
sp. nov.
may have reached Réunion by over-water dispersal. Given the rapid loss of biodiversity on Réunion island and the fact that no additional specimens were re-collected over the last two centuries, it is very likely that
E.
giganteus
sp. nov.
has gone extinct. However, we have unconfirmed evidence that the holotype of
E.
giganteus
sp. nov.
might be a mislabeled specimen from Madagascar, which would refute the presence of native dung beetles on Réunion. We discuss both hypotheses about the specimen origin and assess the systematic position of
E.
giganteus
sp. nov.
by examining most of the described species of Madagascan
Epactoides
. Additionally, we provide a brief overview of the dung beetle fauna of Mascarene Archipelago.
•We studied ground-active beetles in a patchy landscape with two matrix types.•The plantation matrix had fewer and less diverse species than farmland matrix.•Patches with edges of both matrices were ...not intermediate in community composition.•Species in the plantation matrix likely caused biotic homogenisation in patches.•Conservation efforts should concentrate on increasing matrix similarity to patches.
Following landscape change, species invasions and extinctions may lead to biotic homogenisation, resulting in increased taxonomic and functional similarity between previously distinct biotas. Biotic homogenisation is more likely to occur in landscapes where the matrix contrasts strongly with native vegetation patches. To test this, we examined the distribution of ground-active beetles in a landscape of remnant Eucalyptus open woodland patches where large areas of lower contrast matrix (farmland) are being transformed to high-contrast pine plantations in south-eastern Australia. We sampled beetles from 30 sites including six replicates of five categories; (1) remnants adjacent to farmland, (2) remnants adjacent to plantation, (3) farmland, (4) plantation, and, (5) remnants between pine plantation and farmland. Community composition in the pine matrix was similar to native patches embedded in pine (ANOSIM, Global R=0.49, P<0.000), which we suggest is due to biotic homogenisation. Remnant patches with edges of both farmland and pine plantation did not represent an intermediate community composition between patches surrounded by either matrix type, but rather a unique habitat with unique species. Farmland supported the greatest number of individuals (F=9.049, df=25, P<0.000) and species (F=5.875, df=25, P=0.002), even compared to native remnant patches. Our results suggest that matrix transformations can reduce species richness and homogenise within-patch populations. This may increase the risk of species declines in fragmented landscapes where plantations are not only replacing native vegetation patches, but also other matrix types that may better support biodiversity. Our findings are particularly concerning given expanding plantation establishment worldwide.
REPLY TO BARBER Prebble, Matthew; Anderson, Atholl J.; Augustinus, Paul ...
Proceedings of the National Academy of Sciences,
01/2020, Letnik:
117, Številka:
3
Journal Article
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