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Dive into the research topics where Timothy J. Page is active.

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Featured researches published by Timothy J. Page.


Biology Letters | 2005

The taxonomic feedback loop: symbiosis of morphology and molecules

Timothy J. Page; Satish Choy; Jane M. Hughes

Here, we relate the ongoing taxonomic story of a species complex of problematic, cryptic Australian freshwater shrimp (Atyidae; Caridina) to highlight the relative strength and utility of different taxonomic methods in assessing species boundaries. We used popular ‘DNA barcode’ gene fragments cytochrome c oxidase 1 and 16S ribosomal DNA. We then assessed the morphological attributes of these specimens and developed an identification key to complement the molecular results, and conclude that, despite occasionally strident arguments in favour of either molecular or morphological taxonomy, the two are inseparably linked and form parts of a greater whole.


PLOS ONE | 2008

Shrimps Down Under: Evolutionary Relationships of Subterranean Crustaceans from Western Australia (Decapoda: Atyidae: Stygiocaris )

Timothy J. Page; William F. Humphreys; Jane M. Hughes

Background We investigated the large and small scale evolutionary relationships of the endemic Western Australian subterranean shrimp genus Stygiocaris (Atyidae) using nuclear and mitochondrial genes. Stygiocaris is part of the unique cave biota of the coastal, anchialine, limestones of the Cape Range and Barrow Island, most of whose nearest evolutionary relations are found in coastal caves of the distant North Atlantic. The dominance of atyids in tropical waters and their food resources suggest they are pivotal in understanding these groundwater ecosystems. Methodology/Principle Findings Our nuclear and mitochondrial analyses all recovered the Mexican cave genus Typhlatya as the sister taxon of Stygiocaris, rather than any of the numerous surface and cave atyids from Australia or the Indo-Pacific region. The two described Stygiocaris species were recovered as monophyletic, and a third, cryptic, species was discovered at a single site, which has very different physiochemical properties from the sites hosting the two described species. Conclusions/Significance Our findings suggest that Stygiocaris and Typhlatya may descend from a common ancestor that lived in the coastal marine habitat of the ancient Tethys Sea, and were subsequently separated by plate tectonic movements. This vicariant process is commonly thought to explain the many disjunct anchialine faunas, but has rarely been demonstrated using phylogenetic techniques. The Cape Ranges geological dynamism, which is probably responsible for the speciation of the various Stygiocaris species, has also led to geographic population structure within species. In particular, Stygiocaris lancifera is split into northern and southern groups, which correspond to population splits within other sympatric subterranean taxa.


Science of The Total Environment | 2015

Human effects on ecological connectivity in aquatic ecosystems: Integrating scientific approaches to support management and mitigation

David A. Crook; Winsor H. Lowe; Fred W. Allendorf; Tibor Erős; Debra S. Finn; Bronwyn M. Gillanders; Wade Lynton Hadwen; Chris Harrod; Virgilio Hermoso; Simon Jennings; Raouf Kilada; Ivan Nagelkerken; Michael M. Hansen; Timothy J. Page; Cynthia Riginos; Brian Fry; Jane M. Hughes

Understanding the drivers and implications of anthropogenic disturbance of ecological connectivity is a key concern for the conservation of biodiversity and ecosystem processes. Here, we review human activities that affect the movements and dispersal of aquatic organisms, including damming of rivers, river regulation, habitat loss and alteration, human-assisted dispersal of organisms and climate change. Using a series of case studies, we show that the insight needed to understand the nature and implications of connectivity, and to underpin conservation and management, is best achieved via data synthesis from multiple analytical approaches. We identify four key knowledge requirements for progressing our understanding of the effects of anthropogenic impacts on ecological connectivity: autecology; population structure; movement characteristics; and environmental tolerance/phenotypic plasticity. Structuring empirical research around these four broad data requirements, and using this information to parameterise appropriate models and develop management approaches, will allow for mitigation of the effects of anthropogenic disturbance on ecological connectivity in aquatic ecosystems.


Zoologica Scripta | 2012

Regional scale speciation reveals multiple invasions of freshwater in Palaemoninae (Decapoda)

Christopher W. Ashelby; Timothy J. Page; Sammy De Grave; Jane M. Hughes; Magnus L. Johnson

Ashelby, C.W., Page, T.J., De Grave, S., Hughes, J.M. & Johnson, M.L. (2012) Regional scale speciation reveals multiple invasions of freshwater in Palaemoninae (Decapoda). —Zoologica Scripta, 41, 293–306.


Science of The Total Environment | 2015

When trends intersect: The challenge of protecting freshwater ecosystems under multiple land use and hydrological intensification scenarios

Jenny Davis; Anthony P. O'Grady; Allan Dale; Angela H. Arthington; Peter Gell; Patrick Driver; Nick R. Bond; Michelle T. Casanova; Max Finlayson; Robyn Watts; Samantha J. Capon; Ivan Nagelkerken; Reid Tingley; Brian Fry; Timothy J. Page; Alison Specht

Intensification of the use of natural resources is a world-wide trend driven by the increasing demand for water, food, fibre, minerals and energy. These demands are the result of a rising world population, increasing wealth and greater global focus on economic growth. Land use intensification, together with climate change, is also driving intensification of the global hydrological cycle. Both processes will have major socio-economic and ecological implications for global water availability. In this paper we focus on the implications of land use intensification for the conservation and management of freshwater ecosystems using Australia as an example. We consider this in the light of intensification of the hydrologic cycle due to climate change, and associated hydrological scenarios that include the occurrence of more intense hydrological events (extreme storms, larger floods and longer droughts). We highlight the importance of managing water quality, the value of providing environmental flows within a watershed framework and the critical role that innovative science and adaptive management must play in developing proactive and robust responses to intensification. We also suggest research priorities to support improved systemic governance, including adaptation planning and management to maximise freshwater biodiversity outcomes while supporting the socio-economic objectives driving land use intensification. Further research priorities include: i) determining the relative contributions of surface water and groundwater in supporting freshwater ecosystems; ii) identifying and protecting freshwater biodiversity hotspots and refugia; iii) improving our capacity to model hydro-ecological relationships and predict ecological outcomes from land use intensification and climate change; iv) developing an understanding of long term ecosystem behaviour; and v) exploring systemic approaches to enhancing governance systems, including planning and management systems affecting freshwater outcomes. A major policy challenge will be the integration of land and water management, which increasingly are being considered within different policy frameworks.


Marine and Freshwater Research | 2004

Deep phylogenetic structure has conservation implications for ornate rainbowfish (Melanotaeniidae : Rhadinocentrus ornatus) in Queensland, eastern Australia

Timothy J. Page; Suman Sharma; Jane M. Hughes

The freshwater fish, Rhadinocentrus ornatus Regan, 1914, has a patchy distribution through coastal drainages of Queensland and New South Wales, eastern Australia. Isolated populations of R. ornatus are found on several islands, as well as in a disjunct northern population 350 km from its nearest conspecific population. Deoxyribonucleic acid was extracted and sequenced for the mitochondrial ATPase gene to describe the geographic and genetic subdivision within the species. Four major clades were identified. These clades diverged between two and seven million years ago and so represent long-term divisions and possible units of conservation. There are conservation implications in that the narrow and localised distribution of R. ornatus overlaps with an area of large-scale land clearing, high human population and threats from introduced exotic fish. A particularly high centre of Rhadinocentrus diversity in the Tin Can Bay area of Queensland presents some interesting questions about the evolution of the genus Rhadinocentrus.


Journal of The North American Benthological Society | 2008

Evolutionary relationships of atyid shrimps imply both ancient Caribbean radiations and common marine dispersals

Timothy J. Page; Benjamin Douglas Cook; Thomas von Rintelen; Kristina von Rintelen; Jane M. Hughes

Abstract The evolutionary relationships of the surface genera of shrimps of the family Atyidae from the Caribbean were inferred using mitochondrial 16S ribosomal DNA and cytochrome oxidase I gene sequences. The genetic divergence among the 4 Caribbean genera (Atya, Jonga, Micratya, Potimirim) is extensive and dates from between the Eocene and Miocene. This result suggests a vicariant origin or the ancient dispersal of some taxa. Most intrageneric divergences date to the late Miocene–Pliocene and, thus, are probably the result of dispersal. Some species show low levels of intraspecific genetic divergence between distant islands, and thus, present-day or geologically recent gene flow is likely. This gene flow is probably a consequence of the amphidromous life histories of most Caribbean freshwater shrimps. Despite the ancient divergences between the genera, the Caribbean surface atyids form a single evolutionary lineage when compared with atyid shrimp from throughout the world, and this result implies an ancient evolutionary radiation in the Caribbean. The sister group to the Caribbean atyids are the large-bodied and robust Atya-like shrimps of the Indo-Pacific, which share a similar size and shape with Caribbean Atya. Thus, the common ancestor probably was also large and robust. In contrast, the other Caribbean atyids are much smaller, and Jonga has a distinct morphology that is associated with a switch from lotic to lentic environments. This radiation may have been the result of the absence from the Caribbean of other small shrimps that are common in the Indo-Pacific.


Molecular Phylogenetics and Evolution | 2012

Drawn to the dark side: A molecular phylogeny of freshwater shrimps (Crustacea: Decapoda: Caridea: Atyidae) reveals frequent cave invasions and challenges current taxonomic hypotheses

Kristina von Rintelen; Timothy J. Page; Yixiong Cai; Kevin J. Roe; Björn Stelbrink; Bernard R. Kuhajda; Thomas M. Iliffe; Jane M. Hughes; Thomas von Rintelen

Atyid freshwater shrimps are globally distributed and form an important part of freshwater ecosystems, particularly in the tropics and subtropics. Despite their widespread distribution and ecological importance, their phylogenetic relationships are largely unresolved. Here we present the first comprehensive molecular phylogeny of the Atyidae investigating the evolutionary relationships among 32 of the 42 genera using mitochondrial and nuclear markers. Our data indicate that the established classification of the Atyidae is in need of substantial taxonomic revision at all taxonomic levels. We suggest a new suprageneric systematization of atyids and discuss problematic issues at the generic level, particularly in the most speciose genus, Caridina. Molecular clock based divergence time estimates for atyids vary widely, but invariably support the assumption that atyids are an ancient freshwater lineage with an origin in the mid-Cretaceous at the very latest. Atyid distribution patterns are the result of instances of both long-distance dispersal and vicariance, depending largely on the reproductive mode of taxa. From an evolutionary perspective, the high frequency of independent origin of both a complete (landlocked) freshwater life cycle and a cave-dwelling mode of life is remarkable and unparalleled among crustaceans.


Molecular Phylogenetics and Evolution | 2008

Molecular systematics of the Kakaducarididae (Crustacea: Decapoda: Caridea).

Timothy J. Page; John W. Short; Christopher L. Humphrey; Mia Hillyer; Jane M. Hughes

The systematic relationships of the freshwater shrimp family, Kakaducarididae, were examined using mitochondrial and nuclear DNA sequences. Combined nuclear (18S rDNA, 28S rDNA, Histone) and mitochondrial (16S rDNA) analyses placed the kakaducaridid genera, Kakaducaris and Leptopalaemon, as a strongly supported clade within the Palaemonidae, in a close relationship with the genus Macrobrachium. Monophyly of the Australian Kakaducarididae was strongly supported by the molecular data. Estimated net divergence times between Kakaducaris and Leptopalaemon using mitochondrial 16S rDNA equate to a late Miocene/Pliocene split. Within Leptopalaemon, each locality was distinct for mitochondrial COI haplotypes, suggesting long-term isolation or recent genetic bottlenecks, a lack of contemporary gene flow amongst sites and a small Ne. Mitochondrial groupings within Leptopalaemon were largely congruent with several previously recognised morphotypes. Estimated net divergence times between L. gagadjui and the new Leptopalaemon morphotypes equate to a split in the late Pliocene/early Pleistocene. The hypothesis that the Kakaducarididae is comprised of relict species in specialised ecological niches is not supported by the molecular data, which instead suggest a relatively recent origin for the group in northern Australia, sometime in the late Miocene or Pliocene.


PLOS ONE | 2015

Dead Shrimp Blues: A Global Assessment of Extinction Risk in Freshwater Shrimps (Crustacea: Decapoda: Caridea)

Sammy De Grave; Kevin G. Smith; Nils A. Adeler; Dave J. Allen; Fernando Alvarez; Arthur Anker; Yixiong Cai; Savrina F. Carrizo; Werner Klotz; Fernando L. Mantelatto; Timothy J. Page; Jhy-Yun Shy; José Luis Villalobos; Daisy Wowor

We present the first global assessment of extinction risk for a major group of freshwater invertebrates, caridean shrimps. The risk of extinction for all 763 species was assessed using the IUCN Red List criteria that include geographic ranges, habitats, ecology and past and present threats. The Indo-Malayan region holds over half of global species diversity, with a peak in Indo-China and southern China. Shrimps primarily inhabit flowing water; however, a significant subterranean component is present, which is more threatened than the surface fauna. Two species are extinct with a further 10 possibly extinct, and almost one third of species are either threatened or Near Threatened (NT). Threats to freshwater shrimps include agricultural and urban pollution impact over two-thirds of threatened and NT species. Invasive species and climate change have the greatest overall impact of all threats (based on combined timing, scope and severity of threats).

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Kristina von Rintelen

Humboldt University of Berlin

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William F. Humphreys

University of Western Australia

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Mark Adams

South Australian Museum

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