Month: September 2022

ANGIOSPERM HYBRID FREQUENCY. "At least 25% of species form interspecific hybrids, resulting in introgression of characters between species and, rarely, the formation of homoploid hybrid taxa. This process results in complex, reticulate patterns of evolution in many angiosperm groups, making it difficult or impossible to circumscribe species boundaries." https://lnkd.in/dHD-ddW View in LinkedIn

POLYPLOIDY FREQUENCY. "Polyploidy is widespread and is thought to have influenced all angiosperms, having occurred at the base of both the seed plants and angiosperms and within most lineages thereafter, sometimes surprisingly frequently." https://lnkd.in/dHD-ddW View in LinkedIn

ONGOING POLYPLOID EVENTS. "The apparently diploid species A. thaliana, a model species because of its small genome, has undergone three rounds of polyploidization since the divergence of angiosperms, and the existence of natural cultivars with double the expected number of chromosomes reveal that the process is ongoing." https://lnkd.in/dHD-ddW View in LinkedIn

POLYPLOIDY PLUS HYBRIDIZATION. "An analysis of chromosome counts across multiple genera led Wood et al. to predict that polyploidy accounts for 15% of angiosperm speciation events. Furthermore, many polyploids form in association with interspecific hybridization (allopolyploidy)." https://lnkd.in/dHD-ddW View in LinkedIn

FRAGMENT FROM NATURE for this and the next next weekend focuses on the evolution of the leaf. We see them everyday. We have many of them in our houses. They are the emblem of our green planet. But how often have we stopped to contemplate the leaf? Like so many common objects, we become habituated to loosing curiosity about these extraordinary objects. View in LinkedIn

PHYLOGENY OF LEAVES. "The evolutionary origin of leaves within the land plants is heavily debated. Some theories separate all vascular plant leaves into two groups based on their morphology: megaphylls (comprising leaves from seed plants and ferns) and microphylls (comprising leaves from lycophytes)." https://lnkd.in/dFqE_Ne View in LinkedIn

PLANT EMERGENCE. "Vascular plants evolved in the Middle to Late Silurian period, about 420 million years ago. The fossil record indicates that these primitive plants had branched stems with sporangia but no leaves. Leaf-like lateral outgrowths subsequently evolved on at least two independent occasions." https://lnkd.in/dkj5_Ru View in LinkedIn

INDEPENDENT EVOLUTION. "Originally coined to emphasize morphological differences, ‘microphyll’ and ‘megaphyll’ became synonymous with the idea that vascular plant leaves are not homologous. Although it is now accepted that leaves evolved independently in several euphyllophyte lineages, ‘megaphyll’ has grown to reflect another type of homology, that of euphyllophyte leaf precursor structures." http://www.sciencedirect.com/science/article/pii/S1360138508002987 View in LinkedIn