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Twenty-odd species concepts, and conservation law written as if there were one

Anand Kurup Fellow
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Biology & evolutionAnalyticErnst Mayr#biological-species-concept#conservation#environmental-law#species-problem
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Its coordinates: 6.12 Philosophy of Biology

This year a survey of one of the lakes our trust looks after turned up two populations that look almost identical, interbreed where they meet, but differ genetically and in when they spawn. Are they one species or two? The answer is not academic. Our protection schedules, like most conservation law, are written as lists of species.

The textbook answer is Ernst Mayr's biological species concept: a species is a group of populations that actually or potentially interbreed and are reproductively isolated from others. It works for many animals. It fails outright for bacteria and for asexual lineages, and it cannot be applied to fossils at all. So biologists use other concepts as well: lineages with a shared history, groups that can be diagnosed by fixed characters, ecological niches, and so on. Depending on how you count, more than twenty are in use.

Two readings of this situation:

  • The defect reading: "species" is a confused concept, and the plurality shows biology has not yet found what it is tracking.
  • The diversity reading: there are really several kinds of biological grouping, and life simply does not divide itself in one way.

I lean towards the second. But if that is right, a law that protects "species" is choosing one grouping among several, often without saying so, and that choice decides which of my two fish populations gets protected. Is there a principled way to make it?

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3 replies

  1. Ignacio Cárcamo

    Fellow

    The marine version is cryptic species: animals we treated as one species for a century turn out, once we sequence them, to be several lineages that have been separate for a long time. Every time it happens, a "common" species becomes two or three rare ones overnight, without a single animal changing. That is your problem in its sharpest form: the conservation status follows the concept, not the fish.

    My own answer is that the law should protect lineages that are evolutionarily distinct and ecologically meaningful, whatever we name them. Some legal systems already protect distinct populations below the species level, which seems to me an honest admission that "species" was never quite the unit.

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  2. Aroha Tipene

    Fellow

    From Aotearoa, a different approach entirely. In 2017 our law recognised the Whanganui River as a legal person, Te Awa Tupua, an indivisible whole from the mountains to the sea. Protection there does not start from a list of kinds. It starts from relationships: the river, the iwi and everything living in it. I'm not saying that solves your fish. But it suggests the species list is one way of carving up what we owe, and not the only one.

  3. Anand Kurup

    Fellow

    Both answers point the same way, and I find that encouraging: protect the lineage or the whole system, not just the name. Aroha, the river case is close to what our wetland communities say anyway. They talk about the lake, not about its species. Perhaps the science and the older way of speaking are less far apart than our legal schedules make them look.

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