It's about time I stopped drip-feeding these Vanuatu photos and presented the "best of the rest".

I've had a very tough time trying to identify most of the bugs that I came across in Vanuatu - there aren't really any resources dedicated to invertebrates in Vanuatu or even Melanesia in general so it's a matter of trying to ID each creature as far down the taxonomic scale as possible then hope there is something recorded for that taxon in Vanuatu. Thankfully, I got a helping hand in idenfying this odd looking fly:

Ted MacRae encountered a similar looking fly in his travels through Brazil (and took a much better photo, you shold check it out) and he had the skill and the perserverance to work out his fly was from the family Neriidae (sometimes called cactus flies or stalk legged flies).

Evidently, the feature that seperates Neriids from realted families is the bristle like "arista" on the top of the antennae which is nice and clear in this photo. Neriid species from the genus Telostylinus have been recorded from New Caledonia (which is adjacent to Efate, the island on which were staying in Vanutatu) and the black and white stripes on this fly suggest its from this genus. If you look at Ted's photos, you can see the forelimbs of male Neriids are spiked, a feature you usually see in predators like crab spiders and robber flies which need to grab and hold their prey. Neriids eat rotting plant material, which is unlikely to escape their grip. It seems the spikes are used when males wrestle and strike each other in the hope of gaining access to females.

Here's the first invertebrate I saw after landing in Vanutatu:

You'd have to try very hard to miss these massive orb web spiders, in the fifteen minute drive from the airport to house at which we stayed I spotted five or six. In town, they tend to set up their webs on power lines and between houses. I gather they are Nephila plumipes, one of the golden silk orb weavers. Unfortunately, becuase they weave their webs at such great heights and I couldn't get close enough to them, these photos don't really show how massive these spiders are.

Female Nephilla are the largest of the web building spiders, their bodies alone are about 50 mm long and their webs span 2 metres. If you look closley at the photos above you'll see some much smaller spiders in the same web as the massive one. The smaller spiders could very well be 'kleoptoparasites', species that live within the webs of larger spiders and steal their host's prey. But, it's also quite possible some of the smaller spiders are males of N. plumipes, eyeing up the much larger female as a potential mate.

It seems the evolutionary process that made Nephilla females so large left the males of the genus behind. In fact, small males are probably less likely to mistaken for food by the large females, so it's even possible that males of these species got smaller at the same time as the females grew. Whatever the reason, Nephilla males are often ten times smaller than their mates. This is the bit where I would have tried to explain some of the mechanics of spider sex, but, rather wonderfully, Isabella Rosellini, has already done that:

Thanks to Alex Wild for finding that video, his post presenting includes a great photo of the difference between a male and a female Nephilla.

I think there's room for one more spider from Vanuatu as the last of terrestrial invertebrates from my trip. An unidentified orb weaver in the sun at the Mele Cascades waterfall:

Labels: diptera, environment and ecology, fly, nephilla, nerridae, photos, sci-blogs, spider, vanuatu

I appear to have run out of Sunday in which to write about bugs. No matter, I think I have a photo that'll more than make up for a lack of words on my part.

Face to to face with one of the orange dragonflies that spent their days zooming over (and, in this case, falling into) the swimming pool at our house in Vanuatu.

and the close up

That's all from me today (I have to get back to writing about statistics and land snail gut contents, which is actually surprisingly interesting),if you're a fan of these beautiful bugs theres a couple of posts about dragonfly's closest cousins the damselflies here.

Labels: Anisoptera, dragonfly, environment and ecology, Odonata, photos, sci-blogs, vanuatu

There can't be many countries in which you could end up on national TV for staying up all night and writing a blog post criticising someone, but New Zealand is one them.

I knew when Campbell Live aired that interview with Ken Ring there was going to be a great deal of interest in his predictions, but I never imagined just how far my post on the topic would reach. It got more than a years worth of normal traffic for me and my wierd bugs and was quoted by an AFP article and Radio New Zealand's Mediawatch (one step towards my life goal of being interesting enough to be interviewed by Kim Hill). Then I got contacted by Tristam Clayton from Campbell Live, who was putting together a follow-up to that first interview and wanted to include me. I think the hour or so I spend filming that interview isthe scariest thing I've ever done, and I was very nervous from start to finish. Somehow, they managed to cut together a few minutes that make me sound as if I know what I'm talking about, and I'm very happy with the way it turned out. I don't think the TV3 site lets you embed their videos, but you can go and see it here (the site isn't geo-locked, so, foreign friends, you should be able to laugh at my accent):

Ken Ring’s quake theories – how scientific are they

Labels: sci-blogs, science and society

We've had a stunningly beautiful day here in Dunedin. It's been feeling pretty autumnal around here lately, so there was no way I was going to spend any more time in front of a keyboard than was strictly necessary. As a result today's post is going to be short, but, I think, rather sweet. The insects in our garden seemed to be enjoying some summery weather too. Like this bumblebee I caught visiting a Tradescantia flower. In this shot you can see the ocelli - the set of "simple" eyes on the top of the head and gauge the intensity of light.

In this photo you can see the feature that brought these bees to New Zealand.

There are a few native bee species in New Zealand, but none of them have a tongue quite like Bombus hortorum, and that's why we have bumblebees. European settlers tried to introduce red clover as a pasture, but the native bees and the (already introduced) honey bee couldn't reach into the flowers well enough to pollinate them. This meant early farmers had to import fresh seed almost every season, and were desperate to work get clover to set seed. An English naturalist by the name of Charles Darwin had talked about the pollination of red clover in a little book called The Origin of Species:

From experiments which I have tried, I have found that the visits of bees, if not indispensable, are at least highly beneficial to the fertilisation of our clovers; but humble-bees alone visit the common red clover (Trifolium pratense), as other bees cannot reach the nectar *

Evidently, someone in Canterbury had read their Darwin, so the acclimatisation society asked their contacts in the UK for some queen bumblebees to establish local populations. In the end four species (B. hortorum, B. terrestris, B. subterraneus and B. ruderatis) took hold and now the lovely baritone buzz of bumblebees fliting from one flower to the next is a part of summer in New Zealand.

The acclimatisation societies which were set up in New Zealand were basically ecological vandals, introducing familiar European species with no thought to what they'd do the native inhabitants . These are the people that introduced trout to our streams (decimating native fish species) and stoats and weasels to our forests (driving native birds to extinction). So, it feels bit odd to say that, in the case of bumblebees, the acclimatisation societies actually did something very good. Bumblebees are attracted to big showy flowers of the sort our native flora is lacking in, so they don't displace any native species in forests and their introduction has come an no cost to our native ecosystems. Even better, the thriving populations of bumblebees in New Zealand have the potential to rescue the seriosuly unhealthy populations from which they were sourced . One of the introduced species, B. subterraneus, is now presumed to be extinct in Britain and all of the others are declining due to habitat loss and the overuse of pesticides. Last year, members of the British Bumblebee conservation trust came to the South Island to collect mated queens in the hope of establishing new populations of these bees back home. I gather that particular mission didn't work out, but, if the causes of the bumblebees' decline in Britain can be turned around our bees will be the prefect stock from which to re-establish these species.

*The section from which this quote is pulled is and interesting in that it's one of several proto-ecological ideas in The Origin. Here it is in full:

From experiments which I have tried, I have found that the visits of bees, if not indispensable, are at least highly beneficial to the fertilisation of our clovers; but humble-bees alone visit the common red clover (Trifolium pratense), as other bees cannot reach the nectar. Hence I have very little doubt, that if the whole genus of humble-bees became extinct or very rare in England, the heartsease and red clover would become very rare, or wholly disappear. The number of humble-bees in any district depends in a great degree on the number of field-mice, which destroy their combs and nests; and Mr H. Newman, who has long attended to the habits of humble-bees, believes that ‘more than two thirds of them are thus destroyed all over England.’ Now the number of mice is largely dependent, as every one knows, on the number of cats; and Mr Newman says, ‘Near villages and small towns I have found the nests of humble-bees more numerous than elsewhere, which I attribute to the number of cats that destroy the mice.’ Hence it is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district!

Labels: bumblebee, environment and ecology, insects, photos, sci-blogs

So, last week my little old blog found itself in the middle of a national discussion abuot Ken Ring and his claimed ability to predict earthquakes. In this space of two days that post recieved a good deal more than a year's worth of The Atavism's normal traffic.

And now I have to tell anyone that subscribed to this blog in the wake of that article, hoping perhaps that I'd follow the news of the day and provide analysis of the key claims, that I mainly blog about bugs. I'm an invertebrate fan boy, and dedicate a post a week here to celebrating some creature from that ignored majority. Ninety five precent of animal species don't have a backbone, and the spineless multitude contains some of the most amazing creatures on earth.

Today, I'm going back to photos I took in Vanuatu over christmas and looking at my very favourite group of spiders - the jumping spiders (family Salticidae). Spiders get a bad rap generally, almost none of them pose any threat to us*, and absolutely none of them are going to go out of their way to get us. Some spiders, like the long-legged big-fanged Cambridgea in this post, seem to set of a revuslion somwhere deep within our brains, but others are just down right charasmatic. Jumping spiders are the puppies of the arachnid world: cute inquisitive and apparently unaware of how small they are. I've written about the group before, so lets skip right to the photos:

The big round forward-facing eyes are one of the charactersitc traits of the jumpers, because they are active hunters these spiders need to be able to cast a finely-focused image of their prey. Obviously, this one has used its eyes to good effect, I can't tell what it has clamped between its jaws (or chelicerae, if you want to be accurate). It has eight legs, which makes it a fellow arachnid, the body looks a little mite-like but the legs seem too long for that identification so I'm afraid I can't tell you anything more.

As much as it pains me to put up photos with zero taxonomic information, here's a another jumping spider of unknown affinity. This one was truly tiny, perhaps 3mm across the body, but quite happy to have it's host plant bent out of shape to allow a camera to intrude

That's it from me today. You should know that people much more skilled than I am have taken some terrific photos of jumping spiders. Alex Wild has a stunning ant-mimicking spider here, and Thomas Shahan is the acknowledged master in this field. Here's one example of his focus stacked images:

*In New Zealand it's only the katipo and the (introduced) redback

Labels: arachnophilia, environment and ecology, jumping spiders, photos, Salticidae, sci-blogs, vanuatu

If Ring had really made an isolated and specific prediction that a destructive earthquake would strike Christchurch on February the 22nd then he might be worth listening to. His claim revolves around this post from his website a little more than a week before the event. Here's the quotes he'd like you to pick out from that post:

The window of 15-25 February should be potent for all types of tidal action, not only kingtides but cyclone development and ground movement.

Over the next 10 days a 7+ earthquake somewhere is very likely

You might quibble that the Christchurch quake, at magnitude 6.3, was about 5 times less powerful than the M7 event he'd predicted - but I don't think anyone in Christchurch wants to argue about how strong their quake was. On the face it, it really does look like an amazing coincidence: Ring predicted a quake and it happened. But there is more to it than that, I've been through his site and Ring has also predicted earthquakes for, at least, the 24th of September, the 1st and 7th of October the first week in November, the 20th to the 27th of January, the 1st to the 5th and 19th to the 25th of March and the 17th of April. In fact, in one post, giving him the +/- one day he needs in order to claim he predicted the February 22nd quake , he paints more than half of the time between the start of January and the end of March as earthquake risk:

You can add a fair few false negatives to those false positives. In October he claimed the aftershock sequence would die down, missing the major rumble on boxing day and several times he declared that it was unlikely Christchurch would be face another major quake (tragically wrong).

Thanks to the way our brains work, we generally struggle to evaluate theories of causation and claims of prediction fairly. We are too impressed by occasional "hits" and tend to forget the many "misses" which outweigh them. If we want to be rigorous, how should we react to hearing about Ring's "hit" given the litany of "misses" I list above? As it happens there is a theorem for that. Bayes theorem is one of the most important little pieces of maths going around, because it tells us how to update our beliefs about a given question in light of new evidence, and that's exactly what we should be trying to do if we want to lead a skeptical life. It is maths, but it's not too scary. I'm the sort of person that loses contact with scientific papers as soon as 'Σ's and '∫'s start turning up, so you know if I'm writing this , you can follow it. Before we start, we need to define a couple of terms. Let's call P(KR) the probability Ken Ring can predict earthquakes and P(Prediction) the probability that Ken Ring would have successfully predicted this earthquake. From that we want to calculate how probable the claim "Ken Ring can predict earthquakes" is given his successful prediction, well call that P(KR|Prediction). Once we have those defined it's just a little 3rd form algebra:

So, how are we going to replace those terms with numbers? For now, let's not be one of those close minded skeptical types, ignore how eccentric Ring's methods and takes the evidence as it stands by saying P(KR) is 50%. P(Prediction|KR) is the probability that Ring would have predicted this quake if his methods work. You might be tempted to says this is 100%, but remember, he missed the Boxing Day aftershock and he's repeatedly said Christchurch was unlikely to be hit again, so he's not immune to false negatives either, I'll be generous and give him 90%. The really interesting bit in Bayes Theorem is the bottom term P(Prediction). If we are being agnostic about Ken Ring's abilities then we need to estimate this with regard to both the possibility his method has something going for it and the possibility that it doesn't. We've already said that Ring has an 90% chance of predicting an earthquake if his methods work, what's his chance of 'successfully' predicting a quake even if his methods don't work? This is the most important question you should ask yourself about his claims and it's where all those false alarms come in. Given the 'calendar' above, Ring would have claimed to have predicted the quake if it fell on any of half of the days between January and March. His prediction for February was a little more specific than that, but when you read the post it's still quite vague: "somewhere", "in the ring of fire", "withing 500km of the Alpine fault". I'm going to say, given the huge number of predictions he's made, there was about a 30% chance any day that had an earthquake would have been one Ring had previously predicted. To get P(Prediction) we have to balance each scenario like this:

Now, when we put the numbers in like so...

...we end up with P(KR|Prediction) being 75%. Ring's successful prediction still supports the case that his methods work, but it's hardly the decisive piece of information that allows us to say once and for all that he knows what he's doing. You almost certainly want to put different numbers than I did in that equation, and you should. The idea is not to convince you a particular value is the right one, but to show you how including those false positives in our assessment of his claim changes the way we update our ideas about it and, by extension, how much stock we should put in his future predictions. There is a Bayesian calculator here for anyone that wants to play around with other numbers, over there P(H) is what we called P(KR), P(D|H) is P(Prediction|KR) and P(D|'H) is the probability Ken Ring got it right by mistake (the one I gave 30%).

Skeptics are often accused of being closed minded for sticking to scientific orthodoxy in the light some piece of evidence or other: "If you would just let this evidence stand by itself you'd see my theory is true!". Assessing any evidence by itself, without our background of knowledge on a topic, is not being open minded - it's being willfully ignorant. When we want to compare one theory to another we should use all the evidence available to us, and that includes what we know about how the world works. Ring thinks earthquakes happen when the moon makes its closest approach to the earth (called perigee) and around full and new moons. This next sentence really pains me, but here goes. His theory is not 100% lunacy. The phases of the moon have no effect on the earth [whoops, as pointed out in comments, they kind of do, since they correlate with moons position relative to the sun and contribute to tides, this was included in the models/charts below so doesn't change their conclusions], but the position of the moon in its orbit just might. As every schoolchild knows, the moon exerts a tidal force on the planet and there really are "land tides", tiny swells and lulls in the crust of the earth analogous to the ocean's tides, that ebb and flow through the day. It's just possible that a fault that has been loading up with pressure for hundreds of years is more likely to give way when then moon is close and the tidal forces are stronger. But think about that for even a second and the problem becomes clear. Even if the moon is sometimes the straw that breaks the camels back at a particular fault, you couldn't use the moon to predict an earthquake unless you already new a fault was about to go, i.e., the moon could only predict earthquakes when you could already predict an earthquake!

Ken Ring get's a bit touchy about scientists dismissing his theories out of hand, so let's look at some data. I actually asked Ring for some help with this, but he is yet to answer my email. Luckily, since the September 4th earthquake Paul Nicholls from Canterbury University has been plotting the intensity of the aftershock sequence. He's also plotted the two lunar cycles Ring thinks are responsible for the strength of earthquakes: the lunar distance and the moon's phase. In many ways, this is the data-set in which we are most likely to find support for Ring's ideas. We know for a fact that the faults around the Canterbury plains are going to be under stress while the land sorts itself out after the upheaval in September. If the moon really was pushing already loaded faults past their breaking point we'd expect to see it in this data. Usually the most important statistical test you can perform on a data-set is having a look at it. This is Paul's plot from last night, the slimmer of the two waves on the top represents moons orbit (troughs are perigee, the point Ring thinks is most dangerous) and the larger is the moon's phase (the troughs are new moons).

If you can see any correlation between either of the lunar cycles you're doing a lot better than me. I decided to dig a littler further, and plot the intensity of each day's activity against each of the lunar cycles. First the phases of the moon. Remember, Ring thinks new and full moons are the most dangerous, so we expect a curved relationship higher at either end of the x-axis. We find no such thing (in fact, if anything, it's more dangerous between the new and the full moon):

How about the distance between the earth and the moon? This is the one that makes just a little scientific sense:

This time the relationship at least goes the right way, the quakes seem to be, on average, more powerful when the moon is close. In fact, when you put this data into a model that factors in the general tailing off in earthquake activity following the initial quake, the distance between the moon and the earth is a statistically significant variable with regard to the energy released. And there lies an incredibly important point. "Statistically significant" means unlikely to happen if the null hypothesis (in this case "the moon doesn't effect earthquakes at all") was true, it doesn't mean the result is "powerful", "meaningful", or even "capable of explaining a great deal of the variation in the data". As is often the case, we didn't really believe our null hypothesis to start with, so it's no surprise a large data-set found a significant relationship. But the actual effect of the moon is tiny, it explains about 2% of the variation in the data. The feebleness of the moon as a predictor is obvious when you look at the graph - there are plenty of days when the moon is close and there was not much energy released and, equally, there's a whole lot of days when the moon was far away and there were still magnitude 5 quakes. The moon might well be having an effect on intensity of earthquakes from day to day, but if it can barely explain any of the variance in this data-set, one that was almost designed to test Ring's theories in the best light, how could it predict an earthquake? It can't.

Let's get back to our calculation, last time we started with P(KR) at 50%. I hope you'll agree, having seen the data, that Ken Ring's methods are not the least bit plausible. I going to be outrageously generous and say there's a one in one thousand chance that he can predict earthquakes, so let's plug that into Bayes Theorem, remembering to update P(Prediction) for this new value too:

Which gives us a value of 3 in one thousand. Again, you'll want to put different numbers into the equation, but there's a really important point here. Whenever we hear evidence for some new claim, "a vaccine caused my child's autism", "light behaves as a particle and a wave", "Ken Ring can predict earthquakes (and another one's coming)", we should use that evidence to update our prior knowledge of the world. Sometimes, like the outlandish claim that light can be a particle or a wave depending on how you look at, the evidence will be enough to completely change the we think, more often it will hardly make a blip. I think we can put Ken Ring firmly in the "hardly a blip" category: once you see how implausible his methods are you realise you'd need incredible evidence to believe his predictions and once you see his run of false positives you realise that his "prediction" of last week's earthquake doesn't meet that standard.

The people of Christchurch desperately need information. In the next few weeks they want to know if they'll have to face the terror of last Tuesday again and once they city has pulled itself back up they'll want to understand the future risks for the city. In a climate of such desperation people have a duty to provide only verifiable information and to explain that information's limitations. That's exactly what scientist from GNS and Canterbury University have done when they've spoken to the media. Ken Ring, who lambasted GNS for scaring people with a "knee jerk" comment that a magnitude 6 aftershock could be expected after the September earth quake, has not lived up to that duty and I really hope no one takes him seriously.

Note: I know this is a topic people will want to comment on. I'm writing a PhD at the moment and really can't take time to moderate a comment thread. I'm happy to allow comments, but don't expect instant replies today, or(at sciblogs) for comments to clear moderation straight away.

The data I used for my graphs was scraped from Paul Nicholls site, I chucked it up on google docs for anyone that's interested. I've also uploaded the R code I used to plot/analyse the data - this is an open access debunking! (BTW, did you know both R and the ggplot library I used to make those graphs were developed by New Zealanders? We grow good geeks here.)

Labels: earthquake, Ken Ring, sci-blogs, skepticism