Publications by authors named "Denis Tweddle"
Freshwater ecosystems are highly biodiverse and important for livelihoods and economic development, but are under substantial stress. To date, comprehensive global assessments of extinction risk have not included any speciose groups primarily living in freshwaters. Consequently, data from predominantly terrestrial tetrapods are used to guide environmental policy and conservation prioritization, whereas recent proposals for target setting in freshwaters use abiotic factors.
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- A comprehensive analysis of COI sequences from 48 specimens reveals genetic diversity and relationships among southern African species, particularly those dwelling in freshwater systems of the arid savanna.
- Two species are redetermined with new detailed osteological and coloration information, one being widespread across various southern African drainages, and the other identified as endemic to KwaZulu-Natal's coastal rivers.
- A new species from the Lualaba River in the Congo System is discovered, showing close genetic ties to previously described species, and new lectotypes for the identified species are also designated.
Here, we present a gillnet survey of Lake Liambezi a 370 km shallow ephemeral floodplain lake situated in north-eastern Namibia, which is fed irregularly by the upper Zambezi and Kwando Rivers during years of high flooding. The lake dried up in 1985 and, with the exception of sporadic minor annual inundation events, remained dry until 2007. We describe the temporal succession of fish species over an 8 year period from initial inundation 2007 to maturation in 2014.
View Article and Find Full Text PDFA new species of threadfin bream, Nemipterus flavomandibularis, from the Western Indian Ocean is described and figured. The new species appears most closely related to N. bipunctatus (Valenciennes), but differs principally in colour pattern: N.
View Article and Find Full Text PDFUsing data for 25,780 species categorized on the International Union for Conservation of Nature Red List, we present an assessment of the status of the world's vertebrates. One-fifth of species are classified as Threatened, and we show that this figure is increasing: On average, 52 species of mammals, birds, and amphibians move one category closer to extinction each year. However, this overall pattern conceals the impact of conservation successes, and we show that the rate of deterioration would have been at least one-fifth again as much in the absence of these.
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