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This is not at all what I study, but it seems possible to me that sponges have evolved a tolerance for low oxygen conditions in the billion or so years since th
by rflrob 13y ago
This is not at all what I study, but it seems possible to me that sponges have evolved a tolerance for low oxygen conditions in the billion or so years since they first arose. It's a common mistake to think that because something is morphologically very similar to an ancient form (a so called "living fossil"), that it hasn't undergone any evolution. As long as it has been reproducing and mutating, better adapted versions have always had differential success, hence they've evolved, even if the shape hasn't changed.
- chc 13y agoI thought the point of the study was that these sponges live in an oxygen-rich environment, so there is no pressure for them to develop this trait in the modern world. It doesn't prove it's a primitive trait, but it at least makes it unlikely that it's a recent adaptation.
- thotpoizn 13y agoIs the "oxygen-rich environment" universally true, though? It's not as though oxygen saturation in the ocean is perfectly homogeneous. There are plenty of naturally occurring areas of hypoxia, and one could easily imagine an adaptation which allowed better survival in or near these "dead zones" could be quite useful, at least to localized populations. Is there some obvious reason that dramatically reduces the likelihood that one or more pockets of sponges might have capitalized on such a mutation more recently?