Thursday, November 8, 2012

CSI Elephants: Genetics vs. Poaching.

Since the end of the regretted CSI Miami, no one has heard about what Horatio Caine, head of the crime lab, has been doing. Our special reporter at TEI has tracked him and his team down and found them in the middle of the African savannah. Interview is following. 

Reporter: So, Horatio, tell us what you’ve been doing lately.
Horatio: Counting elephants.
Reporter: I’m sorry, what? 
Horatio: Counting elephants.
Reporter: But… Why?
Horatio: Fair question, my dear fellow. You see, it’s both extremely hard and extremely essential to have a good idea of how many elephants you have in a given environment. It’s important for many reasons: for example, to be able to protect them in the most efficient way, you need to know where they are and how many are out there in a certain area. Since they are an endangered species, it’s also important to be able to evaluate the fluctuations of their population: did the creation of a national park help them? How many died in a given year? Have poaching increased or decreased over a decade?
Reporter: I see… I still fail to understand how you can be useful though. Couldn’t just, you know… count them?
Horatio: It’s more complicated than it seems. Of course, one of the options is to take a little plane, fly over the savannah and go “1 elephant, 2 elephants, 3 elephants…” However, this is a very imprecise method: you may miss many individuals – especially the young, little ones – or count the same ones twice. And let’s not even talk about forest elephants. Another option is dung counting.
Reporter: Dung?
Horatio: Feces.
Reporter, looking horrified: Really? I thought doing research with elephants was making groundbreaking scientific discoveries by day and fighting poachers by night!
Horatio: Actually this is a very commonly used method since it is often the only one available. Unfortunately, it also has many biases. Depending on the season, dung disappears more or less quickly and it's hard to know precisely how many elephants poop a given amount of dung.  And (removes his sunglasses) it’s where the genetics come in (puts his sunglasses on). Do you remember how in my past investigations we could figure out how many individuals were present at a crime scene, and even identify them?
Reporter: Of course! It’s forensic science 101! From things like hair, skin cells or body fluids, you could retrieve a person’s DNA. Since DNA is like an ID card, you could tell apart different individuals. If the criminal was already on the database, you could even identify him!
Horatio: Well, that’s pretty much what we are doing here. We can retrieve DNA from the dung, sequence it, and obtain the genetic ID card of this particular elephant. Each time we find excrement from this individual, we can identify him or her. This way, we can track specific elephants whenever they go and over the course of many years. Of course, there are limitations: like in crime scenes, sometimes it’s hard to retrieve evidences, to get your hands on dung, hair, blood… Even if you do, most of the time, the samples have been outside for a while, and the DNA is in pretty bad shape. But let me tell you this (looks straight at the camera): we’re working on it.
Reporter, looking disappointed: Ok… but is it really only what you do? 
Horatio, snorting his disapproval: Of course it’s not. We also use these genetic evidences to study the composition of the elephant groups and more generally the entire structure of the population. I can’t say much more on the subject right now because my PCR is cooking, but you should really talk a geneticist next time. Let me just tell you this. If we have DNA from several elephants, then we can start having a pretty good idea of how they are related, retrace their maternal lineage and even identify the elephants that share a father.  We can therefore know which males are siring the most babies.
Reporter: Just like how fathers take paternity tests in real-TV shows?
Horatio: Exactly. It’s very important to study the genetic structure of the population. You see, poaching doesn’t simply reduce the number of elephants. It disrupts how they live, how they form herds and how they reproduce. All of this we can observe via genetic measures. For example, poachers preferably kill old males with big tusks, the same males who are at the top of their game with the ladies, if you catch my drift. Without the competition of the Old Ones, you end up with fewer, younger competitors that will dominate the dating scene for many years. It means less potential fathers, more babies from the same dad, so a reduced genetic diversity and potentially more risk for inbreeding. (taking a deep breath and brushing off an invisible hair of his shoulder) What the naked eye cannot see… Genetics can reveal.
Reporter: Ok, ok, I see what that what you’re doing is very interesting: but don’t you miss your old job? The thrill, the chase, pinning criminals on the wall and delivering catchy one liners?
Horatio: Oh, there is plenty of risk and adventure. When elephants’ tusks are found in an airplane in China, we can analyze the DNA and compare it with the one we obtained on a body of a dead elephant in the Congo. This is really helpful to have a better idea of the current trafficking networks and draw an international map of the ivory trade.
Reporter, doubtful: Surely this only happens rarely: after all, you don’t always find the victim of the crime.
Horatio, slightly impressed: Unfortunately, you’re right. We still have a solution for this (smug smile). Researchers may use different methods (mitochondrial DNA markers, allele frequency distributions….), but the principle is the same. Each population of elephants in the wild possesses unique and specific genetic characteristics – a little bit like human populations. If you can collect enough samples in the wild, you can draw a map: population 1 located in country A has these genetic characteristics, population 2 in country B these genetic characteristic and so on… All you have to do when you are in possession of illegal ivory is to sequence the DNA and look at its characteristics. You can then compare with your map and know from which population this elephant was from.
Reporter: Surely DNA is not the silver bullet! Sometimes it fails! Most of the time it is really expensive! What do you do then? Do you let the poachers win?
(Deadly silence)
Reporter, clearing his throat: I… I’m sorry. I’m sure you have other ways.
Horatio: We do, young men, we do. You should go talk to another colleague of mine next time. However, you have a point. All those techniques are extremely expensive and also require an equipment that many countries cannot buy. But we see more and more forensic labs getting created in the western countries that are specifically working to fight poaching and illegal trade. So, let me tell you. (removes sunglasses). There is no rest for the heroes when the bad guys are still out there. And boys, genetics are going to hit you hard. (put on sunglasses)(walks towards the sunset).

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