Year: 2022

BY-PRODUCT. "In theory, modes of organelle transmission could even be explained as an evolutionary by-product of selection forces shaping organellar genomes in a lineage-specific manner." https://lnkd.in/d34vWHz View in LinkedIn

LACKING RECOMBINATION. "On the other hand, the predominance of maternal organelle transmission, along with the virtual absence of sexual recombination between organelles in most lineages of eukaryotic evolution, is striking." https://lnkd.in/d34vWHz View in LinkedIn

FRAGMENT FROM NATURE continues from last weekend in the final section on the reversal of speciation. When I first read about this topic, it was like reading a type of heresy, a new theme quite unknown to me, and so contrary to the Darwinian viewpoint I had been brought up with. Frankly, it was shocking. The undoing of some sort of rigid linear passage of living things, compelled to forward motion, or extinction. But a reversal backwards to an earlier state? View in LinkedIn

BLACK SWAN. Of course, with hindsight, it is well known to biologists today that a Darwinian march of progress is but a cartoonist’s illusion, but remains a widespread belief. That is clear. Stephen Jay Gould criticized the viewpoint: “life is a copiously branching bush, continually pruned by the grim reaper of extinction, not a ladder of predictable progress.” That nature should be non-linear, able to get out of blind alleys of extinction, and re-adapt to new condition which effectively reverse earlier niche specialization, with infinite flexibility, is again perhaps obvious with the benefit of hindsight. https://en.m.wikipedia.org/wiki/March_of_Progress View in LinkedIn

RESTRICTED GENE FLOW. "Pre-zygotic isolation mechanisms mainly involve spatial and temporal isolation (e.g. different spawning sites and time) and sexual selection. The temporal and spatial pre-zygotic isolation mechanism may be important as it restricts gene flow among populations." The onset of speciation. https://lnkd.in/dJy3KuN View in LinkedIn

"SEXUAL SELECTION also represents a potential driver of reproductive isolation (mate choice)." https://lnkd.in/dJy3KuN View in LinkedIn

CLASSIC EXAMPLE. "The American signal crayfish has altered the reproductive behavior of males of three-spined sticklebacks, resulting in “speciation reversal." https://lnkd.in/dJy3KuN View in LinkedIn

DIRE WARNING. "Losing Biodiversity by Reverse Speciation. Recent research provides a dire warning that homogenizing environments may cause the rapid loss of such species through a reversal of the speciation process." https://lnkd.in/dyHisYw View in LinkedIn

"ADAPTIVE DIVERGENCE between populations in response to divergent or disruptive selection is the cause of ecological speciation. In its course, gene flow between diverging populations becomes reduced, either indirectly as a by-product of divergent adaptation, or by direct selection when intermediate genotypes are ecologically less successful." http://www.sciencedirect.com/science/article/pii/S0960982206014138 View in LinkedIn

"REPRODUCTIVE ISOLATION in ecological speciation is due to prezygotic mechanisms (mate choice) and extrinsic (ecology-dependent) postzygotic mechanisms in the absence of intrinsic postzygotic hybrid dysfunction. Better studied examples include insect host races, and adaptive radiations of birds and fish, but ecological speciation is widespread and common." http://www.sciencedirect.com/science/article/pii/S0960982206014138 View in LinkedIn