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Newman E.,Stellenbosch University | Manning J.,South African National Biodiversity Institute | Anderson B.,Stellenbosch University
Annals of Botany | Year: 2014

Background and AimsPollinator landscapes, as determined by pollinator morphology/behaviour, can vary inter- or intraspecifically, imposing divergent selective pressures and leading to geographically divergent floral ecotypes. Assemblages of plants pollinated by the same pollinator (pollinator guilds) should exhibit convergence of floral traits because they are exposed to similar selective pressures. Both convergence and the formation of pollination ecotypes should lead to matching of traits among plants and their pollinators.MethodsWe examined 17 floral guild members pollinated in all or part of their range by Prosoeca longipennis, a long-proboscid fly with geographic variation in tongue length. Attractive floral traits such as colour, and nectar properties were recorded in populations across the range of each species. The length of floral reproductive parts, a mechanical fit trait, was recorded in each population to assess possible correlation with the mouthparts of the local pollinator. A multiple regression analysis was used to determine whether pollinators or abiotic factors provided the best explanation for variation in floral traits, and pollinator shifts were recorded in extralimital guild member populations.Key ResultsNine of the 17 species were visited by alternative pollinator species in other parts of their ranges, and these displayed differences in mechanical fit and attractive traits, suggesting putative pollination ecotypes. Plants pollinated by P. longipennis were similar in colour throughout the pollinator range. Tube length of floral guild members co-varied with the proboscis length of P. longipennis.ConclusionsPollinator shifts have resulted in geographically divergent pollinator ecotypes across the ranges of several guild members. However, within sites, unrelated plants pollinated by P. longipennis are similar in the length of their floral parts, most probably as a result of convergent evolution in response to pollinator morphology. Both of these lines of evidence suggest that pollinators play an important role in selecting for certain floral traits. © 2013 © The Author 2013. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. Source

Edge D.A.,North West University South Africa | Mecenero S.,South African National Biodiversity Institute
Journal of Insect Conservation | Year: 2015

The origins and development of butterfly conservation in southern Africa are explored and the role of the Lepidopterists’ Society of Africa (LSA) in the promotion of butterfly conservation and research is described. LSA members have produced several Red Lists for South African butterflies. The Southern African Butterfly Conservation Assessment project, a joint venture between LSA, the Animal Demography Unit (ADU—University of Cape Town) and the South African National Biodiversity Institute was launched in 2007. This has resulted in a comprehensive and accurate distributional database and rigorous conservation assessments using the IUCN (2010) Red Listing categories and criteria for the 794 butterfly taxa assessed. LSA’s Custodians of Rare and Endangered Lepidoptera programme aims to conserve all the threatened species, prioritising the Critically Endangered category. Moving beyond species-based conservation, habitat and landscape conservation are now key conservation strategies which focus on vegetation types and butterfly biodiversity hotspots. LSA (in partnership with ADU) has also recently launched the LepiMAP project, an online photographic geo-referenced database which will develop a butterfly and moth atlas for the whole of Africa, as part of a continent-wide conservation effort. Another important project which the LSA recently launched is the Caterpillar Rearing Group, for documenting the life histories of all Lepidoptera in the Afrotropical region. © 2015, Springer International Publishing Switzerland. Source

Based on detailed morphological studies of a large number of herbarium specimens from various herbaria, a review of the fern genera Dryopteris and Nothoperanema in Madagascar and neighbouring Indian Ocean islands, including Saint Paul, is presented. Eleven species and a putative hybrid are recorded for the region, seven of these are considered endemic to the region. © Publications Scientifiques du Muséum national d'Histoire naturelle, Paris. Source

Sirami C.,South African National Biodiversity Institute | Sirami C.,University of Cape Town | Monadjem A.,University of Swaziland
Diversity and Distributions | Year: 2012

Aim: This study investigates changes in bird communities between 1998 and 2008 in four savanna sites in Swaziland and the extent to which shrub encroachment is responsible for these changes. Location: Swaziland, southern Africa. Methods: Generalized estimated equations were used to estimate changes in bird species occurrence between 1998 and 2008. Remote sensing of aerial photographs/satellite images was used to assess vegetation changes during the same period. We assessed the role of shrub encroachment for bird communities by testing the relationship between change in species occurrence and species habitat using a general linear model. We also estimated species richness, colonization and extinction and used general linear models to test the effects of vegetation changes on these parameters. Results: More than half of the bird species showed a significant change in occurrence between 1998 and 2008: 32 species increased and 29 decreased. Change in species occurrence was significantly explained by species habitat. Species significantly increasing were mainly associated with wooded savanna, whereas species significantly decreasing were mainly associated with open savanna. Species richness decreased significantly, and this decrease was significantly explained by shrub cover increase at the plot scale (from 24% to 44% on average). Extinction at the plot scale was significantly influenced by the loss of grass cover, while colonization at the plot scale was influenced by tree cover increase. Main conclusions: This study represents the first evidence of temporal changes in bird communities owing to shrub encroachment in southern Africa. Despite its short time frame (10years), this study shows dramatic changes in both vegetation structure and bird community composition. This confirms the general concern for southern African bird species associated with open savanna if current trends continue. © 2011 Blackwell Publishing Ltd. Source

Bond W.J.,University of Cape Town | Midgley G.F.,South African National Biodiversity Institute
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2012

Savannahs are a mixture of trees and grasses often occurring as alternate states to closed forests. Savannah fires are frequent where grass productivity is high in the wet season. Fires help maintain grassy vegetation where the climate is suitable for woodlands or forests. Saplings in savannahs are particularly vulnerable to topkill of above-ground biomass. Larger trees are more fire-resistant and suffer little damage when burnt. Recruitment to large mature tree size classes depends on sapling growth rates to fire-resistant sizes and the time between fires. Carbon dioxide (CO 2) can influence the growth rate of juvenile plants, thereby affecting tree recruitment and the conversion of open savannahs to woodlands. Trees have increased in many savannahs throughout the world, whereas some humid savannahs are being invaded by forests. CO 2 has been implicated in this woody increase but attribution to global drivers has been controversial where changes in grazing and fire have also occurred. We report on diverse tests of the magnitude of CO 2 effects on both ancient and modern ecosystems with a particular focus on African savannahs. Large increases in trees of mesic savannahs in the region cannot easily be explained by land use change but are consistent with experimental and simulation studies of CO 2 effects. Changes in arid savannahs seem less obviously linked to CO 2 effects and may be driven more by overgrazing. Large-scale shifts in the tree-grass balance in the past and the future need to be better understood. They not only have major impacts on the ecology of grassy ecosystems but also on Earth-atmosphere linkages and the global carbon cycle in ways that are still being discovered. © 2012 The Royal Society. Source

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