“Rapid Mosaic Brain Evolution under Artificial Selection for Relative Telencephalon Size in the Guppy (Poecilia Reticulata)”, 2021-11-10 (; similar):
The mosaic brain evolution hypothesis, stating that brain regions can evolve relatively independently during cognitive evolution, is an important idea to understand how brains evolve with potential implications even for human brain evolution.
Here, we provide the first experimental evidence for this hypothesis through an artificial selection experiment in the guppy (Poecilia reticulata).
After 4 generations of selection on relative telencephalon volume (relative to brain size), we found substantial changes in telencephalon size but no changes in other regions. Further comparisons revealed that up-selected lines had larger telencephalon, while down-selected lines had smaller telencephalon than wild Trinidadian populations.
Our results support that independent evolutionary changes in specific brain regions through mosaic brain evolution can be important facilitators of cognitive evolution…The rate of evolution shown here is similar to that seen when brain size was the target of selection (24); a 9% difference in brain mass between the large-brain and small-brain lines was found after 2 generations of artificial selection and a 15% difference after 5 generations of selection (50). In contrast to the aforementioned artificial selection experiment on relative brain size in guppies, which found a clear reduction in fecundity (ie. lower offspring number) in the large-brain lines (24), we did not find any evidence for any reproductive trade-off with telencephalon size