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Gastropod chromosomal evolution rates are slower than placental mammals but faster than previously thought. When comparing species of similar ages, evolutionary rates are similar across mammals, frogs, lizards, and snails.

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Area of Science:

  • Evolutionary Biology
  • Genomics
  • Paleontology

Background:

  • Mollusks and non-mammalian vertebrates generally evolve slower in morphology and karyotype than placental mammals.
  • Previous estimates of chromosomal evolution rates in gastropods may have been underestimated.

Purpose of the Study:

  • To recalculate and reassess chromosomal rates of evolution in gastropods using a broader taxonomic sample.
  • To compare evolutionary rates across different vertebrate and invertebrate groups.

Main Methods:

  • Utilized new calculations on previously established measures of chromosomal evolution rates.
  • Employed a larger and taxonomically broader sample of gastropods.
  • Compared fossil-based measures of karyotypic evolution across genera of similar geological ages.

Main Results:

  • Chromosomal evolution rates in gastropods were found to be underestimated but remain lower than the fastest-evolving placental mammals.
  • When comparing genera of similar geological age, karyotypic evolution rates showed minimal differences (less than an order of magnitude) among placental mammals, frogs, lizards, and snails.
  • Limited data on within-group rate variation prevents clear generalizations about among-group differences in chromosomal evolution.

Conclusions:

  • Chromosomal evolution in gastropods is slower than in rapidly evolving placental mammals, but previous estimates were too low.
  • Karyotypic evolution rates are broadly similar across major vertebrate and invertebrate groups when accounting for geological time.
  • Further research with more extensive data is needed to clarify group-specific chromosomal evolution rate differences.