Browsing by Author "Treasure, Anne M."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    South African research in the Southern Ocean : new opportunities but serious challenges
    (Academy of Science of South Africa, 2013) Treasure, Anne M.; Moloney, Coleen L.; Bester, Marthan N.; McQuaid, Christopher D.; Findlay, Ken P.; Best, Peter B.; Cowan, Don A.; De Bruyn, P. J. Nico; Dorrington, Rosemary A.; Fagereng, Ake; Froneman, P. William; Grantham, Geoff H.; Hunt, Brian P. V.; Meiklejohn, Ian; Pakhomov, Evgeny A.; Roychoudhury, Alakendra N.; Ryan, Peter G.; Smith, Valdon R.; Chown, Steven L.; Ansorge, Isabelle J.
    South Africa has a long track record in Southern Ocean and Antarctic research and has recently invested considerable funds in acquiring new infrastructure for ongoing support of this research. This infrastructure includes a new base at Marion Island and a purpose-built ice capable research vessel, which greatly expand research opportunities. Despite this investment, South Africa’s standing as a participant in this critical field is threatened by confusion, lack of funding, lack of consultation and lack of transparency. The research endeavour is presently bedevilled by political manoeuvring among groups with divergent interests that too often have little to do with science, while past and present contributors of research are excluded from discussions that aim to formulate research strategy. This state of affairs is detrimental to the country’s aims of developing a leadership role in climate change and Antarctic research and squanders both financial and human capital.
  • Thumbnail Image
    Item
    Species-energy relationships of indigenous and invasive species may arise in different ways – a demonstration using springtails
    (Nature Publishing Group, 2019-09-24) Treasure, Anne M.; Le Roux, Peter C.; Mashau, Mashudu H.; Chown, Steven L.
    ENGLISH ABSTRACT: Although the relationship between species richness and available energy is well established for a range of spatial scales, exploration of the plausible underlying explanations for this relationship is less common. Speciation, extinction, dispersal and environmental filters all play a role. Here we make use of replicated elevational transects and the insights offered by comparing indigenous and invasive species to test four proximal mechanisms that have been offered to explain relationships between energy availability, abundance and species richness: the sampling mechanism (a null expectation), and the more individuals, dynamic equilibrium and range limitation mechanisms. We also briefly consider the time for speciation mechanism. We do so for springtails on sub-Antarctic Marion Island. Relationships between energy availability and species richness are stronger for invasive than indigenous species, with geometric constraints and area variation playing minor roles. We reject the sampling and more individuals mechanisms, but show that dynamic equilibrium and range limitation are plausible mechanisms underlying these gradients, especially for invasive species. Time for speciation cannot be ruled out as contributing to richness variation in the indigenous species. Differences between the indigenous and invasive species highlight the ways in which deconstruction of richness gradients may usefully inform investigations of the mechanisms underlying them. They also point to the importance of population size-related mechanisms in accounting for such variation. In the context of the sub-Antarctic our findings suggest that warming climates may favour invasive over indigenous species in the context of changes to elevational distributions, a situation found for vascular plants, and predicted for springtails on the basis of smaller-scale manipulative field experiments.