We synthesize the evolutionary implications of recent advances in the fields of phylogeography, biogeography and palaeogeography for shallow-water marine species, focusing on marine speciation and ...the relationships among the biogeographic regions and provinces of the world. A recent revision of biogeographic provinces has resulted in the recognition of several new provinces and a re-evaluation of provincial relationships. These changes, and the information that led to them, make possible a clarification of distributional dynamics and evolutionary consequences. Most of the new conclusions pertain to biodiversity hotspots in the tropical Atlantic, tropical Indo-West Pacific, cold-temperate North Pacific, and the cold Southern Ocean. The emphasis is on the fish fauna, although comparative information on invertebrates is utilized when possible. Although marine biogeographic provinces are characterized by endemism and thus demonstrate evolutionary innovation, dominant species appear to arise within smaller centres of high species diversity and maximum interspecies competition. Species continually disperse from such centres of origin and are readily accommodated in less diverse areas. Thus, the diversity centres increase or maintain species diversity within their areas of influence, and are part of a global system responsible for the maintenance of biodiversity over much of the marine world.
Marine provinces, founded on contrasting floras or faunas, have been recognized for more than 150 years but were not consistently defined by endemism until 1974. At that time, provinces were based on ...at least a 10% endemism and nested within biogeographic regions that covered large geographic areas with contrasting biotic characteristics. Over time, some minor adjustments were made but the overall arrangement remained essentially unaltered. In many provinces, data on endemism were still not available, or were available only for the most widely studied vertebrates (fishes), a problem that is ongoing. In this report we propose a realignment for three reasons. First, recent works have provided new information to modify or redefine the various divisions and to describe new ones, including the Mid-Atlantic Ridge, Southern Ocean, Tropical East Pacific and Northeast Pacific. Second, phylogeographic studies have demonstrated genetic subdivisions within and between species that generally corroborated provinces based on taxonomic partitions, with a notable exception at the Indian-Pacific oceanic boundary. Third, the original separation of the warm-temperate provinces from the adjoining tropical ones has distracted from their close phylogenetic relationships. Here we propose uniting warm-temperate and tropical regions into a single warm region within each ocean basin, while still recognizing provinces within the warm-temperate and tropical zones. These biogeographic subdivisions are based primarily on fish distribution but utilize other marine groups for comparison. They are intended to demonstrate the evolutionary relationships of the living marine biota, and to serve as a framework for the establishment of smaller ecological units in a conservation context.
Abstract
Recently, two articles were published in leading scientific journals, each calling attention to an emerging mass extinction. The two are complementary in that they reached the same ...conclusion by using data from contrasting environments. But, the important question in each case is, can the beginning of a mass extinction be confidently predicted from the evidence presented? The two articles are the latest of several publications that have stated the Earth is in the beginning of a great extinction episode that will eventually result in the loss of at about 75% of all living species. The most recent extinction of this magnitude occurred at the close of the Cretaceous about 65 million years ago. The new mass extinction prognosis began about 22 years ago and was based on estimates of species extinction, due to human activities, that had reached thousands of species per year. Although such unsupported estimates soon gave way to more realistic approximations based on documented records, the spectre of a mass extinction has remained. However, I have found evidence that human-caused extinctions have amounted to only about 1.5 species per year for the last 500 years and that these losses have probably been equalled or surpassed by species born (speciation) during that time. Without evidence of substantial net species loss, mass extinction becomes a speculation without substance. The world’s greatest conservation problem is not species extinction but population decline to the point where many species exist only as remnants of their former abundance.
Comparative phylogeography of the ocean planet Bowen, Brian W.; Gaither, Michelle R.; DiBattista, Joseph D. ...
Proceedings of the National Academy of Sciences - PNAS,
07/2016, Volume:
113, Issue:
29
Journal Article
Peer reviewed
Open access
Understanding how geography, oceanography, and climate have ultimately shaped marine biodiversity requires aligning the distributions of genetic diversity across multiple taxa. Here, we examine ...phylogeographic partitions in the sea against a backdrop of biogeographic provinces defined by taxonomy, endemism, and species composition. The taxonomic identities used to define biogeographic provinces are routinely accompanied by diagnostic genetic differences between sister species, indicating interspecific concordance between biogeography and phylogeography. In cases where individual species are distributed across two or more biogeographic provinces, shifts in genotype frequencies often align with biogeographic boundaries, providing intraspecific concordance between biogeography and phylogeography. Here, we provide examples of comparative phylogeography from (i) tropical seas that host the highest marine biodiversity, (ii) temperate seas with high productivity but volatile coastlines, (iii) migratory marine fauna, and (iv) plankton that are the most abundant eukaryotes on earth. Tropical and temperate zones both show impacts of glacial cycles, the former primarily through changing sea levels, and the latter through coastal habitat disruption. The general concordance between biogeography and phylogeography indicates that the population-level genetic divergences observed between provinces are a starting point for macroevolutionary divergences between species. However, isolation between provinces does not account for all marine biodiversity; the remainder arises through alternative pathways, such as ecological speciation and parapatric (semiisolated) divergences within provinces and biodiversity hotspots.
Background
All patients considering joint-preserving hip arthroscopy should be educated on the risk of THA after arthroscopy. The degree of radiographic osteoarthritis predicts subsequent THA. To ...provide patients with the best information, the best radiographic measure that predicts THA after hip arthroscopy should be identified.
Questions/purposes
We therefore determined if Tönnis grade, Kellgren-Lawrence grade, or joint space narrowing was superior in predicting THA after hip arthroscopy.
Methods
We retrospectively reviewed 203 patients 50 years of age or older treated with hip arthroscopy between March 2007 and October 2010. Of these, 96 patients met the study inclusion criteria. Sixty-five did not undergo THAs during the followup time (non-THA group) and 31 patients did (THA group). We determined Tönnis grade, Kellgren-Lawrence grade, and/or joint space narrowing before arthroscopy. The median followup for the non-THA group was 54 months (95% confidence interval, 49.9–58.9 months).
Results
In 81% of the patients, joint space accurately predicted THA or non-THA, whereas Kellgren-Lawrence was accurate in 73% and Tönnis grade was accurate in 65%. On binary logistic regression, the only predictor (r
2
= 0.45) of THA was joint space of 2 mm or less.
Conclusions
Measuring joint space by determining if any measurement is 2 mm or less predicts patients progressing to THA after hip arthroscopy approximately 80% of the time. At this early time point, joint space measurements were the most accurate predictor of THA and should be used in patient education to define the risk of early failure from hip arthroscopy.
Level of Evidence
Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.
Beta titanium alloys were recognized as a distinct materials class in the 1950s, and following the introduction of Ti-13V-11Cr-3Al in the early 1960s, intensive research occurred for decades ...thereafter. By the 1980s, dozens of compositions had been explored and sufficient work had been accomplished to warrant the first major conference in 1983. Metallurgists of the time recognized beta alloys as highly versatile and capable of remarkable property development at much lower component weights than steels, coupled with excellent corrosion resistance. Although alloys such as Ti-15V-3Al-3Sn-3Cr, Ti-10V-2Fe-3Al and Ti-3AI-8V-6Cr-4Mo-4Zr (Beta C) were commercialized into well-known airframe systems by the 1980s, Ti-13V-11Cr-3Al was largely discarded following extensive employment on the SR-71 Blackbird. The 1990s saw the implementation of specialty beta alloys such as Beta 21S and Alloy C, in large part for their chemical and oxidation resistance. It was also predicted that by the 1990s, cost would be the major limitation on expansion into new applications. This turned out to be true and is part of the reason for some stagnation in commercialization of new such compositions over the past two decades, despite a good understanding of the relationships among chemistry, processing, and performance and some very attractive offerings. Since then, only a single additional metastable beta alloy, Ti-5Al-5V-5Mo-3Cr-0.5Fe, has been commercialized in aerospace, although low volumes of other chemistries have found a place in the biomedical implant market. This article examines the evolution of this important class of materials and the current status in airframe applications. It speculates on challenges for expanding their use.
Aim To present an up to date account of the Mesozoic history of India and its relationship to the other Gondwana continents and to Eurasia.
Location Continents surrounding the Western Indian Ocean.
...Methods Utilization of recent evidence of continental relationships based upon research in stratigraphy, palaeomagnetism, palaeontology, and contemporary biotas.
Results The physical data revealed a sequence of events as India moved northward: (1) India–Madagascar rifted from east Africa 158–160 Ma (million years ago), (2) India–Madagascar from Antarctica c. 130 Ma, (3) India–Seychelles from Madagascar 84–96 Ma, (4) India from Seychelles 65 Ma, (5) India began collision with Eurasia 55–65 Ma and (6) final suturing took place c. 42–55 Ma. However, data from fossil and contemporary faunas indicate that, throughout the late Cretaceous, India maintained exchanges with adjacent lands. There is an absence in the fossil record of peculiar animals and plants that should have evolved, had India undergone an extended period of isolation just before its contact with Eurasia.
Main conclusions The depiction of India in late Cretaceous as an isolated continent is in error. Most global palaeomaps, including the most recent one, show India, as it moves northward, following a track far out in the Indian Ocean. But the evidence now indicates that India's journey into northern latitudes cannot have taken place under such isolated circumstances. Although real breaks among the lands were indicated by the physical data, faunal links were maintained by vagile animals that were able to surmount minor marine barriers. India, during its northward journey, remained close to Africa and Madagascar even as it began to contact Eurasia.
Don't judge species on their origins Davis, Mark A; Chew, Matthew K; Hobbs, Richard J ...
Nature (London),
06/2011, Volume:
474, Issue:
7350
Journal Article
Peer reviewed
Open access
By this point, partly fuelled by Elton's book, proponents of biodiversity preservation and ecological restoration commonly used military metaphors and exaggerated claims of impending harm to help ...convey the message that introduced species are the enemies of man and nature. ... the introduction of non-native species has almost always increased the number of species in a region5.
Aim To discuss the impact of new diversity information and to utilize recent findings on modes of speciation in order to clarify the evolutionary significance of the East Indies Triangle. Location ...The Indo-Pacific Ocean. Methods Analysis of information on species diversity, distribution patterns and speciation for comparative purposes. Results Information from a broad-scale survey of Indo-Pacific fishes has provided strong support for the theory that the East Indies Triangle has been operating as a centre of origin. It has become apparent that more than two-thirds of the reef fishes inhabiting the Indo-Pacific are represented in the Triangle. An astounding total of 1111 species, more than are known from the entire tropical Atlantic, were reported from one locality on the small Indonesian island of Flores. New information on speciation modes indicates that the several unique characteristics of the East Indian fauna are probably due to the predominance of competitive (sympatric) speciation. Main conclusions It is proposed that, within the East Indies, the high species diversity, the production of dominant species, and the presence of newly formed species, are due to natural selection being involved in reproductive isolation, the first step in the sympatric speciation process. In contrast, speciation in the peripheral areas is predominately allopatric. Species formed by allopatry are the direct result of barriers to gene flow. In this case, reproductive isolation may be seen as a physical process that does not involve natural selection. Allopatric species formation often takes millions of years, while the sympatric process is generally much faster. Following species formation, dispersal from the East Indies appears to take place according to the centrifugal hypothesis.
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