Year: 2022

GENOME SEQUENCING. "The results — from studies of crows, butterflies, mosquitoes, fish and other organisms — suggest that the concept of species is even more muddled than we thought, and that genetic changes don’t always align with more visible ones, such as appearance. In some cases, species have big morphological and behavioral changes with only a few genetic changes, and in other cases, there is lots of genetic change with few visible results." https://lnkd.in/eKBjZs5 View in LinkedIn

BUTTERFLY SPECIES. "Genome analysis suggests that the two species are swapping genes at a surprising rate. But each species has genome segments unique to its own kind, which seem to persist despite the mixing of the rest of the genome. Scientists have dubbed such regions of the genome “islands of speciation.” https://lnkd.in/eKBjZs5 View in LinkedIn

QUASI-SPECIES. "An RNA virus population does not consist of a single genotype; rather, it is an ensemble of related sequences, termed quasispecies. Quasispecies arise from rapid genomic evolution powered by the high mutation rate of RNA viral replication." https://lnkd.in/eb_myZ8 View in LinkedIn

ADVANTAGES OF SPECIES BARRIERS? Natural selection can increase reproductive isolation (the Wallace Effect). Allopatric selection from adaptive divergence also leads to an increase in speciation. The production of viable offspring is the key driver in nature. Differences in molecular construction and compatibility can lead to sterility or in viable offspring. Perhaps it is all just an accident of molecular incompatibility, just like sexual organ incompatibility can cause a barrier, rather than a competitive advantage. View in LinkedIn

SO ENDS Part One on the issue of speciation. Hybridization between species, quasi-species and horizontal gene transfer illustrate that tidy species barriers leading to reproductive isolation can be breached. Darwin's view of the evolutionary drive to species formation has dominated biology until recently. Now, it appears that perhaps enriching the global gene pool by any mechanism may be a stronger driver. View in LinkedIn

NUCLEATED CELLS. "Eukaryote cells are all evolutionary chimaeras of an ancestrally phagotrophic host cell with nucleus, endomembranes, and endoskeleton and an enslaved α-proteobacterium converted into a mitochondrion close to the time when the nucleus itself originated." https://lnkd.in/enZ4-ZD View in LinkedIn

"THE TRANSITION from prokaryotes to eukaryotes was the most radical change in cell organisation since life began, with the largest ever burst of gene duplication and novelty. This radical transformation of cell structure (eukaryogenesis) is the most complex and extensive case of quantum evolution in the history of life." https://lnkd.in/enZ4-ZD View in LinkedIn

BURST IN GENE DUPLICATION AND NOVELTY appears to have been one of the complexification steps in the emergence of new life forms, interrupting longer periods of genetic simplification. These events are poorly understood, to say the least. View in LinkedIn

THE NUCLEUS WAS A VIRUS. "The current interpretation is that the precursor of the eukaryotic nucleus was indeed a huge membrane-covered DNA virus that persistently colonized a prokaryotic host." Add to that fact that the mitochondria (animal energy cell) was a bacteria, as was the plant chloroplast (the plant powerhouse). All the top cellular jobs taken by our friends the microbes. https://lnkd.in/e-pJFM6 View in LinkedIn

LARGE DATA REVIEW. "To test the predictions of competing and mutually exclusive hypotheses for the origin of eukaryotes, we identified from a sample of 27 sequenced eukaryotic and 994 sequenced prokaryotic genomes 571 genes that were present in the eukaryote common ancestor and that have homologues among eubacterial and archaebacterial genomes." https://lnkd.in/eqauQJt View in LinkedIn