The BBC reports on the world’s shortest-lived vertebrate:
The pygmy goby lives an average of 59 days, pipping the previous record holder, an African fish which lives for just over two-and-a-half months.
Nothing fishy about the story so far. But now:
A team from James Cook University in Australia reports that the tiny coral reef goby lives a frantic existence to avoid becoming extinct.
No. No. And thrice no.
I bet they don’t report anything of the sort. Or if they do, they should know better.
There is no force, process or phenomenon on Earth – other than the efforts of a few eccentric humans – that specifically counteracts the extinction of any species. That includes the evolution of the goby’s own genes. There is absolutely no reason to believe that the 59-day lifespan is optimal for the survival of the goby species. It is optimal for spreading through the goby population in competition with both 58-day and 60-day variants. That’s all. If the species dies as a result, evolution and the species’ genes will neither ‘know’ nor ‘care’.
For all we know, the optimum life span to avoid extinction of the species is 63 days, or a year, or a hundred years. No, that’s not where species selection comes in. If there are a thousand isolated populations of gobys living under the same selection pressures, it is not the case that the one that happens to host a mutant, optimally-species-preserving hundred-year-lifespan gene will still be around when all the other populations have gone extinct: it will go extinct first, in the sense that it will be rapidly taken over by ever shorter-lived mutants, in whose favour, we know, the selection pressure operates. Species selection, if it happens at all, can only be a vanishingly rare, insignificant phenomenon.
And they’re not ‘living a frantic existence’ to avoid the predators, any more than they are living a sluggish existence to avoid whatever marginally impedes the replication of 58-day variants. They are adapted.