The Last of Us

I thought that we’d do a quick, just-for-fun post today.  ABOUT ZOMBIES.  Now, I like me some zombie movies.  Sometimes their plots even have cool disease ecology components, like competition between the “zombie virus” and other host pathogens.  On the other hand, there are many, many biological inaccuracies involved in the popular zombie idea, as Neil deGrasse Tyson explains.  

But if you’ve been following this blog or popular science for any length of time, you know that in a way, Neil deGrasse Tyson is wrong in saying that if zombies exist, they only exist on other planets.  There are “zombies” on Earth: parasite zombies!  That is, some parasites can dramatically alter their host’s behavior, so that the host is effectively just a vehicle for the parasite.  The point of this manipulation is to get the host to behave in such a way as to increase the parasite’s probability of transmission to the next host.  Usually, this involves the host getting eaten by the next host, like when infected ants hang out at the top of blades of grass, where they are likely to be eaten by cows or sheep.  But that’s not always the case.  For instance, with rabies – the pathogen most similar to the classic idea of a zombie virus –  the virus makes (some) animals behave aggressively, and this increases the probability that the virus will be transmitted to new hosts via bites.  

Now, thankfully, there aren’t any parasites that re-animate dead corpses…yet.  But there are parasites that use corpses as points of transmission.  For instance, Cordyceps fungus makes ants leave their normal routines to go bite onto leaves above major areas of ant traffic.  Then the fungus sprouts a fruiting body out of the ant’s corpse and rains spores of death down on the ant’s extended family.  

Don’t you think that a Coryceps fungus apocalypse would be a cool video game plot?  Well, actually, it already is a cool video game plot!  The Last of Us has been out for a while on PS3, and a remastered version was just released on PS4.  From Wiki:

“In 2013, Joel (Troy Baker) is a single father living near Austin, Texas with his twelve-year-old daughter Sarah (Hana Hayes). One night, an outbreak of a mutant Cordyceps fungus ravages the United States, which transforms its human hosts into cannibalistic monsters…”

Now, real Cordyceps doesn’t turn insects into cannibals, but I’m willing to overlook this error in biology because – WAIT FOR IT – they’re going to make The Last of Us into a movie, too!  That’s right.  Cordyceps is coming to the big screen.  Awwyisss.     

Godzilla Parasites

WARNING: GODZILLA SPOILERS ARE CONTAINED WITHIN THIS POST.

A few weeks ago, I went to see Godzilla.  I hadn’t looked up the plot summary or anything beforehand, so imagine my surprise when out of the giant pulsing “spore” (ahem, egg) emerged something that looked a lot like a cross between a giant water bug and Alien…not Godzilla.  And then imagine my UTTER GLEE when they said that the thing that was not Godzilla was a parasiteSwoon.  I immediately conjured up all kinds of plot possibilities, and I couldn’t wait to see how the parasites attacked Godzilla!

But then I quickly realized that the “parasites” were not parasites at all.  The parasites acquired energy from radioactive material.  For instance, they ate nuclear warheads.  And that alone doesn’t make them parasites.*  It makes them autotrophs.  I thought I might have missed the parasite explanation, so after the movie, I did some googling.  But all I could find was some people saying that the parasites (or their young) might try to feed on Godzilla’s radioactive energy.  I would totally buy that, if the parasites had searched for Godzilla in the movie.  But instead, Godzilla searched for the parasites.  In fact, he was their “predator.”  WHAT?!  Yo, Hollywood.  You need a parasite ecology consultant?  HMU.

So, I wrote you guys a different plot, with actual Godzilla parasites in it.  Except that they aren’t parasites, per se.  They’re parasitoids.*  Enjoy!

—–

The female parasitoid hatches from an egg in a mine in the Philippines.  The female parasitoid goes to the Janjira nuclear plant to feed and causes a giant explosion.  A lady dies, and it’s sad.  The female parasitoid forms a chrysalis in the wreckage.

Sometime in the next 15 years, the other egg from the mine in the Philippines is taken to the USA to be studied and whatnot.  Then the radioactive body of the male parasitoid – which is thought to be dead – is stored in Yucca Mountain.

After 15 years, the female parasitoid emerges from her chrysalis.  She has wings!  (Yes, it is the male who has wings in the movie, but I don’t like it that way.)  She destroys a bunch of stuff and kills a dude and it’s sad.

The male (he’s alive!) and female parasitoids start communicating via echolocation (ok, whatever, I’ll go with it).  They start trying to find each other, stopping only to ransack ships and whatnot so that they can eat radioactive material.  When they find each other, the male fertilizes the female.  The male also gives her a nuptial gift of a nuclear warhead, because that was really cute.  Then he dies because he’s a male and he no longer has a purpose in life.  ONE MONSTER DEAD.  Huzzah!

Now the female needs a host for her eggs.  So, while armed forces are trying to shoot her to bits, she uses her highly adapted sensory apparatus to seek out Godzilla.  When she finds Godzilla, she stabs her ovipositor (yes, she has one of those now) into Godzilla’s body cavity and deposits a single egg.

Godzilla2(And you guys thought my artwork was limited to snails!)

Then the female parasitoid tries to fly off to find another Godzilla so that she can lay another egg, because that’s what parasitoids do.  But Godzilla grabs her head and breathes plasma down her throat, and she dies. SECOND MONSTER DEAD.  Huzzah!

The world starts to rejoice because all the parasitoids are dead, but suddenly San Francisco is being trampled by Godzilla!  Someone left some giant war heads in San Francisco, and Godzilla is being manipulated by the parasitoid larvae into finding and eating more radioactive material!  Oh no!  But wait, one of the nuclear warheads has an analog detonator thingy, so the parasitoid’s EMP abilities can’t stop it from detonating now that it has been activated!  Godzilla eats it!  1 hour and 29 minutes later, Godzilla and the parasitoid within explode.  ALL THE MONSTERS ARE DEAD!

Some soldier and his lady kiss and stuff.  The end!

*If you don’t remember the difference between a parasite, a predator, and a parasitoid, check this out.

Excuses, excuses, excuses!

So, I’m a week late on posting.  Sorry, Guys!  I was setting up a mesocosm experiment, and I didn’t have time to finish editing the aggregation posts.  I’ll have them up shortly!  To make it all up to you, I’m going to show you something really pretty.  We (s)nail polished a bunch of snails – like, 640 of them – last week, and you can bask in the adorableness that is painted snails while you wait for the next post.

PaintedSnails

Most Prolific Parasite Ecologists of the 21st Century

I had a lot of fun playing on Web of Science last week when I was trying to figure out whether parasitism is underrepresented in the ecological literature.  At one point, I accidentally sorted by author instead of journal, and I realized that I could easily generate a list of The Most Prolific Parasite Ecologists of the 21st Century!  And so I did!

I searched Web of Science for any papers with parasit* as the topic, while excluding anything with parasitoid as the topic.  I only searched in the years 2001 to 2013, because apparently the year 2000 doesn’t count as the 21st century.  Finally, I narrowed the search results down to include only these journals: PNAS, Proceedings of the Royal Society B, Oecologia, Oikos, Ecology, American Naturalist, Journal of Animal Ecology, Ecology Letters, Functional Ecology, Trends in Ecology Evolution, Ecological Applications, Journal of Applied Ecology, and Journal of Ecology. Using this method, the top 30 most prolific parasite ecologists of the 21st century are:

  1. HIDDEN MOMENTARILY FOR DRAMATIC EFFECT
  2. AP Moller
  3. PJ Hudson
  4. KD Lafferty
  5. BR Krasnov
  6. H Richner
  7. M Boots
  8. D Ebert
  9. PTJ Johnson
  10. AF Read
  11. LH Miller
  12. A Buckling
  13. FJ Ayala
  14. JC de Roode
  15. MA Duffy
  16. SR Hall
  17. P Schmid-Hempel
  18. S Morand
  19. CE Caceres
  20. J Jokela
  21. AM Kuris
  22. S Gandon
  23. IS Khokhlova
  24. D Mouillot
  25. RE Ricklefs
  26. WH van der Putten
  27. S Altizer
  28. DH Clayton
  29. T Day
  30. A Fenton

And the Golden Cercariae Award for The Most Prolific Parasite Ecologist of the 21st Century goes to: Robert Poulin!  Runners up get free access to everything on the Parasite Ecology blog for a year.  😉

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So, my search method obviously had some issues.  For instance, a few people who are probably more parasitologists than parasite ecologists made it onto the list, most likely because I included PNAS in my list of journals.  Also, the exact order of authors is a bit finicky, because some authors only differed by one or two publications.  That means that including slightly different journals might jumble the order.  But in general, I’d say that this is a pretty good list!  If you’re wondering, you needed to get at least 13 publications in the journals that I listed to make it in the top 30 – roughly one publication per year, on average.

Who do you think the Most Prolific Parasite Ecologist of the 20th Century was?

Ecological interactions: is parasitism under-represented in the ecological literature? [UPDATED]

I read a lot of papers about parasite ecology.  I try to stay up-to-date on the literature, and I also try to blog mostly about “new” papers, so that my posts are interesting to people in my field as well as my general audience.  When I’m scrounging for awesome new papers to blog about, I find myself wondering: why aren’t there more parasite ecology papers?!  When you consider that at least 50% of all organisms are parasites, and 100% of species have at least one parasite species, it seems like more ecology papers should be about parasites.  Is parasitism under-represented in the ecological literature?

This post is a quick analysis.  I feel like I’ve seen something like this in the literature before, but I couldn’t find it.  Please link me in the comments if you know of something published! [UPDATED:  See below*]

I used Web of Science to calculate the number of papers related to parasitism, predation, mutualism, and competition that were published in various popular ecology journals since the year 2000.  That’s four key words: parasit*, predat*, mutual*, and competit*.  Papers might end up in searches for multiple terms, but we’ll assume that there are relatively few of those papers.  Here are the raw data:

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Parasites certainly seem under-represented in some journals, like Ecology.  But in others, like PNAS, parasites (almost) rule supreme! I’m not sure whether that is just completely idiosyncratic or if it actually means something.  However, I did notice that higher impact journals tend to have relatively more parasite papers:

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Finally, to look at overall trends, here are the data lumped together across all journals:

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Mutualisms need some TLC.  And while we’re at it, let’s focus on mutualisms beyond plant-pollinator and plant-mycorrhizal fungi systems!

Parasitism does appear to be under-represented!  When you consider that at least 50% of all organisms are parasites, it seems like more than 21% of ecology papers should be about parasites.

I suppose a large number of “parasite ecology” papers may end up in non-ecological journals, like Parasitology, International Journal for Parasitology, etc., whereas there is no Predatorology journal.  Do you think that might account for the under-representation of parasitism in the popular ecology journals?

***Someone very kindly linked me to a TREE paper by Raffel et al. (2008) that did something somewhat similar.  You can access the PDF here.  Raffel et al. (2008) were reviewing the ways that we can use concepts from predator-prey ecology to inform research in parasite-host ecology.  They also looked at the number of ecological papers regarding parasites and predators, and found that about 10% of ecological papers were about parasites, while about 20% were about predators.  I didn’t look at proportions of total papers like they did – I just did straight numbers of papers, so my “percentages” aren’t exactly comparable.  However, it looks like we both found that parasitism is underrepresented in the ecological literature.

Oarfish Parasites

I’m sure you guys heard about the two dead oarfish that were found in California this month.  Well, the UCSB ecological parasitology lab just made national news after they took a look at their parasites!  Identifying those parasites helped to figure out what the elusive fish eat, and who eats them.  Cool stuff!

You can check out a detailed article here, and definitely watch this interview with Armand Kuris: