18 August 2005

Moving right along...

Well, I'm now officially registered for graduate courses for the first time. Taking only seven credits feels way too light, but all the current grad students keep laughing when I say that. For the moment, my schedule is making me jump up and down - I'm only spending nine or ten hours a week in the classroom. We'll see what I really think later, when I get sylabi next week.

16 August 2005

Applications of Evolution 1 - The Erythrina Gall Wasp

Invasive species are nothing new to the Islands of Hawai'i. The first invasive species arrived with, and included, the first Polynesian settlers. Although there does appear to be some evidence that they may have caused the extinction of a few endemic species, the effects of these invasions were most likely relatively minor. Since the first western contact with the islands, the number of invasive species present has skyrocketed, causing a massive ecological disaster. If you want proof of the severity, you need not look any farther than the fact that Hawaii contains well less than 1% of the total land area of the US, but has over a third of the listed endangered species in the US.

At the moment, there is a new invasive species that is making the news here in Hawai'i: a species of "gall wasp" that has been wrecking havoc on trees of the genus Erythrina in Singapore, Taiwan, and a number of other places was found in a valley on Oahu in April. Since then, it has been found in a large number of other places on Oahu, and has started to turn up on other islands, including Maui, and a number of scientists believe that it poses a serious threat to a culturally-significant endemic plant - the Wiliwili (Erythrina sandwichensis). The threat is being taken so seriously that scientists have reportedly begun to bank Wiliwlil seeds as a precaution in case the extant population is completely lost.

So what does this have to do with evolution?

Individual species do not evolve in a vacuum. They evolve in an environment, and natural selection favors the preservation of variations that increase the chances for an organism to survive within that environment. This is common knowedge. What people sometimes forget, however, is that when we discuss the "environment" that an organism evolves in, we are talking about much, much more than just the climate. The evolutionary environment also includes every other species of organism that has any sort of effect on it. Species evolve within the ecosystem or ecosystems that they inhabit, and they evolve as a part of those ecosystems.

So what happens when people - either intentionally or inadvertantly - introduce a species to a new habitat? That's a broad question, and one where the answer is obviously going to depend on a lot of things - not least, what the new species is, and where it is being introduced. (Biology can be really annoying that way, with the answers to so many questions depending on specific circumstances.)

Since the broad question isn't really answerable, let's narrow it in a way that is tailored to these specific circumstances: what happens if you introduce a pest species (either parasite or predator) into a new, hospitable environment that contains a species that is closely related to the pest's usual target? That is a very complexly worded question, but it has a simple answer. Nothing good is going to happen.

In the case of the Erythrina gall wasp, this is exactly what happened. The gall wasp is not native to Hawai'i, and it did not evolve here. This means that up until now, it has not been a part of the evolutionary environment for any of the native species. As a result, it should come as no surprise that the native species has no natural defences against the gall wasp. At the same time, the gall wasp has now found itself in an environment where it has lots of access to a number of species that it can use, and which completely lacks any of it's normal predators. In short, it's gall wasp heaven out here - at least until the Erythrina are all gone.

In fact, the wild success of the gall wasp is one of the reasons that we can tell that it is an invasive, rather than a previously undiscovered native. Its mode of reproduction damages the trees that it uses, if too many wasps use the same tree. Right now, that is exactly what is happening in Hawaii, and it is happening to such an extent as to kill the trees. If it continues to happen at current rates, it is quite possible that the entire genus Erythrina will be wiped out across the Hawaiian Islands. The wasps are loving life right now, but they are actually not in a situation that bodes well for their long-term success in Hawaii - if the current trend continues, they will fall victim to their own success. This indicates that it is not likely that this species evolved here. If it had, one would expect that it would have a lifestyle that would not be so massively counterproductive in the long term. That is not, I should add, because evolution looks forward to see what will work in the long term, but because an organism that has evolved here has already been here for the "long term".

Evolution explains why invasive species can be such a major problem. And evolution, combined with a bit of thought, also can provide us with some possible solutions. With an invasion like this, where the insects involved are tiny and the number of hosts enormous, chemical methods of insect control are normally ineffective. The only real hope for permanently controlling the problem is to find some sort of biological control method. This is normally a natural parasite or predator of the pest. Of course, this can be risky, since the biological control agent is itself an invasive species. If you are not careful, you can easily wind up with a situation that is similar to the children's song about the old lady who swallowed the fly:

She swallowed the goat to catch the dog ...
She swallowed the dog to catch the cat.
She swallowed the cat to catch the bird ...
She swallowed the bird to catch the spider
That wriggled and jiggled and wiggled inside her.
She swallowed the spider to catch the fly.
But I dunno why she swallowed that fly

Ultimately, however, it may be impossible to save the Wiliwili without some sort of biological control. So let's assume that a decision is made to look for one. Normally, we would look to the species' native habitat to find a parasite or predator. Unfortunately, we don't actually know what the native range of this species actually is. It was only described for the first time last year, and it seems to be an invasive in all of the places that it has been found. The world is a really big place, and we have a limited amount of time until the Wiliwili follows countless other Hawaiian species into extinction. So where do we start to look?

Africa. Since this species hasn't been described from there at all yet, what makes us think that we should look there?


There are a number of related species of gall wasp in South Africa, including some that utilize Erythrina trees. There are also Erythrina trees that are native to this area. As I understand it from conversations with other grad students here, these trees do not appear to be experiencing the same sort of massive infestation that is being seen here in Hawaii. This indicates that one of two things is happening there. Either the South African Erythrina have an innate defence mechanism protecting them from the gall wasps (this is unlikely, as the gall wasps can and do breed using these trees) or there is something else, most likely a predator or parasite, keeping their population in check. This is the type of more stable ecological relationship that we expect to see in areas where the species evolved.

I don't know whether or not sufficient funding will be found to do this, but I predict that a thorough study of the gall wasps in South Africa will turn up a predator and/or parasite capable of controlling the gall wasp population. (Or that the Erythrina trees have a defence mechanism protecting them from gall wasps.) I also predict that, again pending sufficient funding, that molecular studies will show that the wasps invading Hawaii are relatively closely related to species from South Africa.

Looking back over this long post, I see that evolution is actually extremely informative in this case - both in understanding what is happening, and as a tool to help develop responses to the situation. To summarize, this is what evolution allows us to do in this situation:
1) Identify the gall wasp as being more likely to be invasive than endemic
2) Understand why this invasive has such a bad effect on the Wiliwili.
3) Identify biological control as a possible method of containment.
4) Narrow the search for the home range of the organism.
5) Predict future findings.

This is all just something to keep in mind the next time that a creationist tries to convince you that evolution is just airy speculation, with no real practical use. That might be what creationists wish were the case, but the reality is actually much different. Evolution is used as a basic tool in the biological sciences, and it often has real-world, practical implications. This particular example comes from the field of invasion biology, but other examples can be found in all other areas of the biological sciences.

Update: A follow-up thread can be found here. Comment threads to both this post and the follow-up thread can also be found at The Panda's Thumb.

This is your brain...

... after spending 6 1/2 consecutive hours learning how to be a good TA.

If you're lucky, anyway. I don't think my brain is that solid anymore.

15 August 2005

All the king's horses and all the king's men...

This is by way of being an introductory Iraq post. It gives my basic position on the politics of the conflict as a whole, and my reasons for simultaneously expressing two opinions that are rarely seen together: the administration's entire Iraq policy has been an unmitigated disaster from the start, and we need to stay the course. These opinions may appear to be contradictory at first glance, but I think that the second is actually a moral consequence of the first.

For the last couple of days, I've had Iraq on my mind. The reports that have been kicking around about exit strategies and reductions in troop levels have left me completely torn. On the one hand, I really, really hope that we will, just so that my wife's upcoming (fall, 2006) deployment will be postponed or cancelled. On the other, I think that withdrawing at any point in time before Iraq can reasonably be expected to survive as some sort of moderately safe and stable society is just plain wrong.

I don't think we should stay in Iraq because it will benefit the United States - it probably won't. I don't think we should stay in Iraq because it helps our national interests - it probably doesn't. As far as I can see, there is only one reason for us to stay in Iraq: at the moment, Iraq cannot function independently, and that is our fault. Municipal services, local government, regional government, national government, adequate security services - you name it, they don't got it. And it is our fault, as a nation. Many of us did not vote for Bush, but that is not relevant. He was and is the president, and had the power to make those sort of decisions on behalf of the country. He may have made the mistakes, but we all share the responsibility for them. Responsible people do their best to clean up the mistakes that they make; the world has the right to expect that responsible nations do the same.

I do not approve of the decisions that the administration made that placed us in Iraq. I approve even less of the way that they conducted the war, and the way that they failed in their basic responsibility to prepare for the aftermath. Countless errors have been made through to this point in time, and virtually nobody has been held accountable for them. I am angry beyond belief at the administration for making so many arrogant mistakes, and I cannot forgive them for the way they have retained and promoted those who were most responsible for the errors. I am nauseated at the thought that more of our troops will die, and terrified that the casualty lists will include members of my own family. But if we are to maintain any sort of respect in the global community - if we are to be worthy of any respect - then I don't know what else we can do.

There is no easy answer to the question that John Kerry asked in 1971: "How do you ask a man to be the last man to die for a mistake." It is even harder for me to face, knowing that the people who may die for the mistake include many of my friends and neighbors, my brother-in-law, my brother, and my own wife. It sounds like something awful to ask, and it is, but I only see two alternatives remaining. We can either ask more American troops to die trying to fix American mistakes, or we can ask even more Iraqis to die to fix American mistakes. That's it. The situation is so totally fucked up that there is absolutely no way that it will get fixed without more deaths, and there is no doubt that the USA was responsible for a large amount of the fuck-up.

If we pull our troops out of Iraq now, as some have suggested, then we will almost certainly save the lives of many of our own troops. However, we will almost certainly be creating a situation where many Iraqis will die as a result of unrest and civil war. It may be that such a situation might have arisen after Saddam died, had he remained in power. It might also be that something like this might have happened as a result of a violent revolt against Saddam's tyrany. Unfortunately, the situation did not arise because of either of those events. It has come about because we sent troops into Iraq, threw out the dictator running the place, and then sat around with our thumb up our ass trying to figure out what to do.

The administration, with the assistance of members of both parties of congress, has gotten us into a humpty-dumpty mess. We have created a disaster in Iraq, and all the king's horses and all the king's men may not be able to fix it. Nevertheless, we are morally obligated to try our best to get it done, despite the sacrifices that it will undoubtedly require.

14 August 2005

Wildlife Picture: Ghost Crab

This little guy is a pallid ghost crab (Ocypode pallidula Jacquinot 1852). These crabs are small (usually under 3 cm carapace width) scavengers that live in high intertidal to supertidal areas where there is sand. They have an Indo-Pacific distribution, and are indigenous to the Hawaiian islands.

Photo taken 14 August 2005 at Kualoa Beach Park, Oahu
1/1000 sec at F11, 300mm lens.

Kansas BOE wants to lie to students - Part 3

It's time for our next look at the Kansas Board of Education majority's continuing crusade to push their own narrow-minded sectarian agenda at the expense of actual education. Today's entry can be found on page 80 of the draft science standards (available as a pdf on the Kansas Department of Eduation's website):

Grade 8-12 indicator 7: explains proposed scientific explanations of the origin of life as well as scientific criticisms of those explanations.

It's worth noting at this point that this particular indicator is not present in the March 9th draft of the science standards (also available as a pdf) - the one written by the science standards committee without excessive input from the elected BoE members. It is a recent addition by the Board of Education. I am not, however, planning to devote time and energy to discussing the indicator itself. My concern is more with the "additional specificity" points that they list with this new indicator.

7. Some of the scientific criticisms include:
a A lack of empirical evidence for a “primordial soup” or a chemically hospitable pre-biotic atmosphere;
b. The lack of adequate natural explanations for the genetic code, the sequences of genetic information necessary to specify life, the biochemical machinery needed to translate genetic information into functional biosystems, and the formation of proto-cells; and
c. The sudden rather than gradual emergence of organisms near the time that the Earth first became habitable.

It's really hard to figure out what the most objectionable part of that list is. There are just so many different objections.

It might be the highly questionable accuracy of those statements (for example, see Mark Isaak's Index of Creationist Claims entry CB035 for a discussion of the early atmosphere issue).

It is possible that it is the implication that a current lack of an "adequate" natural explanation is somehow positive evidence that a supernatural explanation is needed. It is also possible that the most objectionable component of this list is their failure to specify what they mean by "adequate".

It could even be the nonsensical nature of some of the "scientific criticisms" - what would a "gradual" emergence of organisms look like, and what evidence of that would reasonably be expected to be preserved?

Any of those things could be the the most objectionable thing about this list. Were the members of the KBOE's conservative majority hindered by even the slightest hint of honesty or ethical conduct, one of them might be. However, the KBOE majority has, yet again, demonstrated an unbelievable amount of sheer chutzpah - because those three items are all of the material that they have seen fit to place in the draft.

Let's look at this again. The KBOE's new indicator reads:
Grade 8-12 indicator 7: explains proposed scientific explanations of the origin of life as well as scientific criticisms of those explanations.
[emphasis mine]

7. Some of the scientific criticisms include...

Wow. Looks like they forgot to mention what the scientific explanations actually are. You'd think that they would at least try to make a point of demonstrating something that bears some faint resemblance to even-handedness, wouldn't you? After all, this is the same group of people who claim that their objectives are:

1) to help students understand the full range of scientific views that exist on this topic, 2) to enhance critical thinking and the understanding of the scientific method by encouraging students to study different and opposing scientific evidence, and 3) to ensure that science education in our state is “secular, neutral, and non-ideological.”

Is it just me, or is their failure to list any of the "proposed scientific explanations for the origin of life" just slightly inconsistent with all three of those stated objectives?