Chapter 6: More Bang for Your Buck (Comments due Tuesday, 3/17, 9 p.m.)

In this chapter, we start to get to the "evo" part of "evo-devo." Here are some things I was thinking while reading this chapter:

  • In the fossil record, we see a few episodes of rapid diversification of species interrupting long stretches of stasis (what Niles Eldredge and Stephen Jay Gould termed punctuated equilibria.) Why does the development of new animal forms not (apparently) occur at a constant rate? Relatedly (perhaps), why do we see bursts of innovation in inventions throughout human history, interrupting longer periods of cultural stasis, rather than new inventions being thought up at a constant rate?
  • Is it scientifically fair to name hypothetical animals (like Urbilateria, Fig. 6.2) that we know must have existed, but that we don't (and likely never will have) fossils of? Is naming something that we don't actually have unscientific (like coming up with names for unicorns and pixies), or is it a necessary part of doing science? As scientists, how much evidence should we have for the existence of something before giving it a name?
  • Speaking of the hypothetical Urbilateria, the common ancestor of us and our fruit fly friends was a long, long time ago—long enough that the embryonic development of fruit flies is pretty radically different from our human embryonic development (them being protostomes & us being deuterostomes & all). How superawesome is it that we have so very many of our developmental pathways still in common, such as the hox, pax, tinman genes??!?
  • How does gene duplication allow for the evolution of new forms?
  • The evolutionary geneticist J.B.S. Haldane is rumored to have said, in response to a question about what his study of biology had taught him about the nature of God, "that God is inordinately fond of beetles." Why have arthropods been so obscenely successful among animals, anyway? What aspects of arthropod development have allowed them to become numerically dominant among Earth's animals, and have allowed them to diversify into such an overwhelming array of forms, since the Cambrian explosion? And why will they not accept that it's NOT OK for them to eat vertebrates? (Don't click on link if you agree that such insubordinate behavior on the part of centipedes is NOT OK.) Also not ok: arthropods bigger than people.
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