Month: September 2022

SONG OF DARWIN. "The more I study nature, the more I become impressed […] that the contrivances and beautiful adaptations [acquired through natural selection] transcend in an incomparable degree [those] which the most fertile imagination of the most imaginative man could suggest with unlimited time at his disposal." https://lnkd.in/eykUy37 View in LinkedIn

FLATFISH are highly adapted for their life in the sea floor. They are fast, well hidden and social. See this little clip of their life. https://lnkd.in/djdpYRR View in LinkedIn

FLATFISH METAMORPHOSIS TIME LAPSE. https://lnkd.in/dBUnSKn View in LinkedIn

REMARKABLE PECULIARITY. "Even Charles Darwin, one of the co-discoverers of the theory of evolution by natural selection, was baffled by what he referred to as this “remarkable peculiarity” of flatfish morphology." https://lnkd.in/dvMVSjN View in LinkedIn

HOPEFUL MONSTERS. "There are no known transitional fossils with only partially displaced eyes that would link these asymmetrical flatfishes with their symmetrically shaped relatives. This lack of transitional fossils has been the source of tremendous scientific controversy regarding whether this asymmetry evolved gradually or through a sudden evolutionary leap that produced “hopeful monsters,” as originally described by geneticist Robert Goldschmidt in the 1930s." https://lnkd.in/dvMVSjN View in LinkedIn

WEAK LINK. "Although the transformation of symmetrical larvae into asymmetrical juveniles is well documented, the evolutionary origins of flatfish asymmetry are uncertain because there are no transitional forms linking flatfishes with their symmetrical relatives. The supposed inviability of such intermediates gave pleuronectiforms a prominent role in evolutionary debates, leading to attacks on natural selection and arguments for saltatory change." https://lnkd.in/d4qWcVu View in LinkedIn

TRANSITIONAL FORMS FOUND. "Amphistium and the new genus Heteronectes, both extinct spiny-finned fishes from the Eocene epoch of Europe, are the most primitive pleuronectiforms known. This condition is intermediate between that in living pleuronectiforms and the arrangement found in other fishes. Amphistium and Heteronectes indicate that the evolution of the profound cranial asymmetry of extant flatfishes was gradual in nature." https://lnkd.in/d4qWcVu View in LinkedIn

SALTATIONS AND SMALL STEPS. "Step size in evolution is rapidly becoming a major subject of interest to biologists. Traditionally, small changes alone were seen as significant in evolution, and any large differences between an ancestor and its descendant could be explained entirely by the accumulation of many small steps." https://lnkd.in/dDbgqi3 View in LinkedIn

IMPORTANT QUESTION. "Whether the evolution of major adaptations is mainly a matter of amassing such small increments of change, or if a significant proportion occurs through the inclusion of one or more large steps, is vital to the understanding of how evolution works." https://lnkd.in/dDbgqi3 View in LinkedIn

BIG STEP CANDIDATES. "Four “classic” examples of animals—flatfishes, turtles, bolyerine snakes, and gastropod molluscs—each of which has seemed difficult to interpret as resulting from a continuous series of tiny increments." https://lnkd.in/dDbgqi3 View in LinkedIn