Science a GoGo's Home Page Forums General Discussion General Science Discussion Forum Intersex sunfish found in Potomac basin

"SHEPHERDSTOWN, W.Va. - Scientists studying intersex fish in the Potomac River basin have found the abnormality for the first time in redbreast sunfish, the third species affected by the mysterious phenomenon, a federal fish pathologist said Tuesday.

Intersex fish possess both male and female characteristics. For example, some male fish have been found with immature eggs in their testes."

http://news.yahoo.com/s/ap/20070123/ap_on_sc/chesapeake_fish_kills

Maybe this is more of a canary than a sunfish!

That's the way I read it.

Me too. But it's evolution in action. Perhaps the whole sex thing for these fish will change.

Only if you equate evolution with humans introducing toxins into an environment and killing off all but a small percentage of a species.

DA. You obviously accept evolution is simply adaptation of species to their environment. Just because in this case it's human-induced change doesn't alter the fact that it's environmental change. Humans have been altering the environment since the first fire got away on them, perhaps deliberately. Besides, the arrival of any new species alters the environment, often drastically, as we know only too well here in NZ.

In Mexico, families living near a battery factory have a very high incidence of babies born with no or only partial brains. Is that evolution or adaptation? I think neither.

There are several fish (and I think other animals) that can switch sex during their lives. The parrot fish is one example. There are others. Probably most creatures have the ability to have both sex organs. Plants do it regularly.

This is a mutation. It's not necessarily an adaptation.

The thing to remember about evolution is this: there are no guarantees of survival. Our best estimates say something more than 95% of all species that ever lived are now dead.

You are correct TNZ. The difference, as I see it, is that evolutionary changes tend to be gradual. Yes there's been the occasional asteroid and such that's made a mess of things but then we refer to those as extinction events.

What I see different here is that we are consciously manufacturing toxic substances and using the oceans and atmosphere as inexpensive substitutes for trash cans.

We are overwhelming nature's ability to evolve and thus possibly precipitating another great die-off.

TFF asked:

"Is that evolution or adaptation?"

I guess if the new version is more effective at surviving in the new environment then it becomes an adaptation. It will lead to evolution if this adaptation leaves more descendants . Of course a mutation becomes an adaptation only if it leads to survival. Are these fish able to reproduce? Do the babies born with partial brains survive? I believe I know many people with partial brains.

DA wrote:

"evolutionary changes tend to be gradual."

Perhaps. But we don't really know. What about punctuated equilibrium? We may be observing an actual evolutionary change. If so the evolution-deniers will have some explaining to do.

I totally agree that the poisons we as a species are dumping must have an effect, even if mainly to speed up our own extinction. I actually think "nature" is quite capable of rapid adaptation even though mass extinctions may be involved in the process.