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Consistent phenological shifts in the making of a biodiversity hotspot: the Cape flora
Background
The best documented survival responses of organisms to past climate change on short (glacial-interglacial) timescales are distributional shifts. Despite ample evidence on such timescales for local adaptations of populations at specific sites, the long-term impacts of such changes on evolutionary significant units in response to past climatic change have been little documented. Here we use phylogenies to reconstruct changes in distribution and flowering ecology of the Cape flora - South Africa's biodiversity hotspot - through a period of past (Neogene and Quaternary) changes in the seasonality of rainfall over a timescale of several million years.
Results
Forty-three distributional and phenological shifts consistent with past climatic change occur across the flora, and a comparable number of clades underwent adaptive changes in their flowering phenology (9 clades; half of the clades investigated) as underwent distributional shifts (12 clades; two thirds of the clades investigated). Of extant Cape angiosperm species, 14-41% have been contributed by lineages that show distributional shifts consistent with past climate change, yet a similar proportion (14-55%) arose from lineages that shifted flowering phenology.
Conclusions
Adaptive changes in ecology at the scale we uncover in the Cape and consistent with past climatic change have not been documented for other floras. Shifts in climate tolerance appear to have been more important in this flora than is currently appreciated, and lineages that underwent such shifts went on to contribute a high proportion of the flora's extant species diversity. That shifts in phenology, on an evolutionary timescale and on such a scale, have not yet been detected for other floras is likely a result of the method used; shifts in flowering phenology cannot be detected in the fossil record
Climatic and topographic changes since the Miocene influenced the diversification and biogeography of the tent tortoise (Psammobates tentorius) species complex in Southern Africa
Background: Climatic and topographic changes function as key drivers in shaping genetic structure and cladogenic
radiation in many organisms. Southern Africa has an exceptionally diverse tortoise fauna, harbouring one-third of
the world’s tortoise genera. The distribution of Psammobates tentorius (Kuhl, 1820) covers two of the 25 biodiversity
hotspots in the world, the Succulent Karoo and Cape Floristic Region. The highly diverged P. tentorius represents an
excellent model species for exploring biogeographic and radiation patterns of reptiles in Southern Africa.
Results: We investigated genetic structure and radiation patterns against temporal and spatial dimensions since the
Miocene in the Psammobates tentorius species complex, using multiple types of DNA markers and niche modelling
analyses. Cladogenesis in P. tentorius started in the late Miocene (11.63–5.33 Ma) when populations dispersed from
north to south to form two geographically isolated groups. The northern group diverged into a clade north of the
Orange River (OR), followed by the splitting of the group south of the OR into a western and an interior clade. The
latter divergence corresponded to the intensifcation of the cold Benguela current, which caused western aridifcation
and rainfall seasonality. In the south, tectonic uplift and subsequent exhumation, together with climatic fuctuations
seemed responsible for radiations among the four southern clades since the late Miocene. We found that each clade
occurred in a habitat shaped by diferent climatic parameters, and that the niches difered substantially among the
clades of the northern group but were similar among clades of the southern group.
Conclusion: Climatic shifts, and biome and geographic changes were possibly the three major driving forces shaping cladogenesis and genetic structure in Southern African tortoise species. Our results revealed that the cladogenesis
of the P. tentorius species complex was probably shaped by environmental cooling, biome shifts and topographic
uplift in Southern Africa since the late Miocene. The Last Glacial Maximum (LGM) may have impacted the distribution
of P. tentorius substantially. We found the taxonomic diversify of the P. tentorius species complex to be highest in the
Greater Cape Floristic Region. All seven clades discovered warrant conservation attention, particularly Ptt-B–Ptr, Ptt-A
and Pv-
Adaptive Radiation in Mediterranean Cistus (Cistaceae)
lineage consists of
12 species primarily distributed in Mediterranean habitats and
is herein subject to analysis. lineages), which display asymmetric
characteristics: number of species (2 vs. 10), leaf morphologies
(linear vs. linear to ovate), floral characteristics (small,
three-sepalled vs. small to large, three- or five-sepalled
flowers) and ecological attributes (low-land vs. low-land to
mountain environments). A positive phenotype-environment
correlation has been detected by historical reconstructions of
morphological traits (leaf shape, leaf labdanum content and leaf
pubescence). Ecological evidence indicates that modifications of
leaf shape and size, coupled with differences in labdanum
secretion and pubescence density, appear to be related to
success of new species in different Mediterranean habitats.
Shifts in Climate Foster Exceptional Opportunities for Species Radiation: The Case of South African Geraniums
Solid phase extraction of Am(III) and Cm(III) from acidic feeds using tetraethyl diglycolamide (TEDGA) in ionic liquid
Solvent extraction of Am(III) and Cm(III) with several diglycolamide ligands in an ionic liquid, [C4mim][Tf2N] was investigated from nitric acid medium. Based on the encouraging extraction behaviour with N,N,N′,N′-tetraethyldiglycolamide (TEDGA), extraction chromatographic studies were carried out using a resin material made from Chromosorb-W impregnated with a solution of TEDGA in [C4mim][Tf2N]. The kinetics of metal ion uptake and sorption isotherms were also investigated. The maximum sorption capacity of the resin was estimated to be 20.05 ± 0.73 mg/g