A review of chemical status of the Weija Lake

Weija lake, a man-made lake, was sampled in 1993 at different sites along the lake. The water was slightly alkaline and the temperatures reflected the generally high tropical temperatures and fluctuated with the seasons. The dissolved oxygen concentration was high and varied from site to site being lower at sites with high organic matter. The mean transparency was 60 cm. The dominance pattern for nitrogen compounds for the lake was NO3- ¾ N > NH3 ¾ N > NO2- ¾ N while the ionic pattern was Na2+ > Mg2+ > Ca2+ > K+: HCO3- > Cl- > SO42-. The cation dominance pattern of the lake was similar to sea water near the estuary, but the present study and previous work indicate that the proportions of ions (cations and anions) are changing to that of fresh water. JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 2 No. 2 (2000) pp. 136-14

Phylogenomics and the rise of the angiosperms

Angiosperms are the cornerstone of most terrestrial ecosystems and human livelihoods1,2. A robust understanding of angiosperm evolution is required to explain their rise to ecological dominance. So far, the angiosperm tree of life has been determined primarily by means of analyses of the plastid genome3,4. Many studies have drawn on this foundational work, such as classification and first insights into angiosperm diversification since their Mesozoic origins5,6,7. However, the limited and biased sampling of both taxa and genomes undermines confidence in the tree and its implications. Here, we build the tree of life for almost 8,000 (about 60%) angiosperm genera using a standardized set of 353 nuclear genes8. This 15-fold increase in genus-level sampling relative to comparable nuclear studies9 provides a critical test of earlier results and brings notable change to key groups, especially in rosids, while substantiating many previously predicted relationships. Scaling this tree to time using 200 fossils, we discovered that early angiosperm evolution was characterized by high gene tree conflict and explosive diversification, giving rise to more than 80% of extant angiosperm orders. Steady diversification ensued through the remaining Mesozoic Era until rates resurged in the Cenozoic Era, concurrent with decreasing global temperatures and tightly linked with gene tree conflict. Taken together, our extensive sampling combined with advanced phylogenomic methods shows the deep history and full complexity in the evolution of a megadiverse clade