Today’s life advice comes from the trematodes that castrate their snail hosts, causing snail gigantism.
Today’s life advice comes from the trematodes that castrate their snail hosts, causing snail gigantism.
Today’s life advice comes from the parasites that evolved from the parasites that ate dinosaurs.
Today’s life advice comes from this aphid that parasitizes ant colonies.
*Life advice from parasites is not necessarily endorsed by the author of this blog. Follow at your own risk.
Hello, Readers! I am once again gearing up for a transition in academic positions, which means that posts might be sporadic for a few months. In the meantime, please enjoy some sage life advice from parasites. This week’s advice comes from the nematomorphs.
Students just discovering the joys of parasite ecology often find themselves wondering: how do I get there from here? Or perhaps wondering what a career in parasite ecology even looks like. So I’ve organized this series of posts from well-known parasite ecologists who can give us some insight into how they got started and their suggestions for success. So far, we’ve heard from Dr. Armand Kuris from the University of California Santa Barbara, Dr. Pieter Johnson from the University of Colorado Boulder, Dr. Robert Poulin from the University of Otago, Dr. Kelly Weinersmith from Rice University, and Dr. Tara Chestnut from the National Park Service. Today, we’ll hear from Dr. April Blakeslee, an Assistant Professor at East Carolina University.
Who is Dr. April Blakeslee?
I’ve never met April, but I’ve been following her marine invasion research for years, so I was thrilled when she volunteered to write this guest post for us. April has done a great job of describing her lab’s research at East Carolina University, as well as her prior research at awesome places like the Smithsonian Environmental Research Center, so I’ll let you scroll down to read the details from April herself. I’ll just say that my favorite part of April’s work is that she often uses parasites as clever tools or bioindicators to infer things about host ecology that would be difficult or impossible to figure out otherwise. I wish more people would do this kind of research! But without further ado, here are her insightful answers to my five interview questions:
(1) How long have you been a parasite ecologist, and what do you study?
(2) How did you get into parasite ecology?
“I’m going to answer these two questions together because they actually go hand in hand in regards to my foray into the realm of parasite ecology, which is now one of the main areas of research for my lab. On the whole, my work is fairly multidisciplinary in marine ecology and includes several fields—conservation biology, invasion biology, biogeography, biodiversity, parasite ecology, and evolutionary ecology. Regarding where the parasite work all began… it started with my dissertation work at the University of New Hampshire (co-mentored by Dr. Michael Lesser and Dr. Jeb Byers), which focused on trying to answer a century-long question about the ecological history of a common marine snail in northeastern N. America (Littorina littorea, common periwinkle snail). To do so, we realized we needed to take an approach that utilized multiple lines of evidence, which is ultimately where my love of parasites started!
To resolve the snail’s cryptogenic (origin uncertain) history in N. America, we realized that we could combine both parasites and genetics as a novel tool (to my knowledge, this was the first time they were used together to try to answer such a question) to determine whether the snail was native or non-native. We used parasites as ecological tools in two main ways: (1) looking for a common signature of a marine invasion: parasite escape (i.e., significantly reduced parasite diversity in a host’s non-native versus native region); (2) performing a biogeographic investigation in the native (Europe) and cryptogenic (N. America) ranges to look for genetic founder effects in both the host and its most common trematode parasite (Cryptocotyle lingua).
Altogether, we found significantly lower trematode species richness in N. American versus European Littorina littorea, but no significant differences in trematode richness between the regions in two congener species (L. saxatilis and L. obtusata) native throughout the N. Atlantic. These results suggested parasite escape in N. American L. littorea compared to its congeners (Blakeslee & Byers 2008). Additionally, we found significantly reduced genetic diversity in N. America versus Europe for both the host snail and its trematode parasite, C. lingua. These results suggested genetic founder effects in N. America, another common signature among introduced species (Blakeslee et al. 2008). Altogether, these results (along with other lines of evidence, including historical ecology) suggested to us that L. littorea is likely non-native in northeastern N. America. And parasites were absolutely instrumental to our conclusions.
I began my dissertation work in 2001, so I guess that was the true beginning of my parasite ecology days. Since then, I have continued to look at parasites in a number of different ways—including molecular ecology, biogeography, host-parasite interactions, and the evolutionary ecology of host-parasite relationships. For example, right now we are investigating several parasite projects in my lab: (1) rhizocephalan infection of native Panopeid mud crabs by an invasive parasitic barnacle (Loxothylacus panopaei) and its impacts on host ecology and evolution (collaborating with Dr. Amy Fowler (GMU), Dr. Carolyn Tepolt (WHOI), and the SERC Invasions lab, led by Dr. Greg Ruiz). (2) Trematode infection in invasive and native green crabs (Carcinus maenas), invasive Asian shorecrabs (Hemigrapsus sanguineus), and native rock crabs (Cancer irroratus) (led by my MS student Rebecca Barnard, and also in collaboration with Dr. Carolyn Tepolt and Dr. Carrie Keogh (Emory University)). (3) Using parasites as indicators for biodiversity and conservation in several common hosts, including naked gobies, mud crabs, and mud snails (led by my PhD student Chris Moore). (4) Influence of an invasive ecosystem engineer (Gracilaria vermiculophylla) on community composition, including parasites (led by my PhD student Tim Lee, and in collaboration with Dr. Amy Fowler and Dr. Stacy Krueger Hadfield (UAB)). And there is much more parasite ecology work in addition to that!”
(3) What kinds of skills or training do you look for when you’re considering taking on new (graduate) students?
“I think enthusiasm goes a long way, along with fascination and the desire to want to know more. It’s of course very helpful to have some microscopy, molecular, and field skills, but I think most of those can be fairly-easily trainable. Having some background stats knowledge is also very helpful. So to me, enthusiasm, inquisitiveness, and work ethic are the most important attributes when picking a student for my lab.”
(4) What are the most important things that (graduate) students can do to become successful parasite ecologists?
“Keeping up with the literature and being open to learning new skills are extremely helpful to becoming successful. To me, though, I think probably the most important and rewarding component is being collaborative – you can learn so much from colleagues and mentors. And if you get a good team together, you can bring in expertise and skills from multiple different areas and viewpoints. It’s also much more fun to work in a team—it’s a group of people with whom you can bounce ideas, and also they will hopefully get excited along with you about whatever it is you are working on. You can also convert your peers and colleagues to the importance of parasites in ALL things, which in my opinion, is always a success.”
(5) Is there anything else that you’d like to share with the blog audience?
“I am very happy that this parasite ecology blog exists! I have shared it with multiple students and peers – there are so many good stories and research developments. It is a lot of work to do it, and to do it well, so thank you! :)”
Awwwwwww, shucks! Many thanks to April for her kind words and great advice! It sounds like there is a lot of exciting research cooking in her lab that we’ll need to keep an eye out for. If you’re a student and you’d like to help April convert everyone to seeing “the importance of parasites in ALL things” – one of my favorites pastimes, as well – you should start by checking out her website here.
I’m a few days late, but Happy Taxonomist Appreciation Day! Despite my tardiness, I am troubled by our global shortage of taxonomists, and I strongly support initiatives to (1) train more taxonomists, (2) provide them with livable and enjoyable career opportunities, and (3) find ways to integrate and value their important work amongst other science. I have mostly thought about this from a parasite conservation perspective, and I recently read an excellent paper that resonated with those thoughts. Below are some quotes (and my commentary) from Shaw and Hochberg (2001) that describe a parasite taxonomy crisis and some potential solutions:
Britain has a long history with natural history. For centuries, amateurs and professionals have been collecting and describing species from that relatively small land mass. In Britain, people probably don’t even seem like weirdos for gleefully wielding their custom-ordered extendable butterfly nets in public spaces. (Whatever, I’m not bitter, or anything.) Anyways, you might think that all of that enthusiasm for natural history has led to a complete inventory of Britain’s wildlife. But you’d be wrong.
“While the public may hold reasonably accurate perceptions that tropical ecosystems are teeming with unrecognized species, the average person in Britain is unaware that knowledge of the British biota – widely acknowledged as the best studied in the world – is also very limited.”
How could our taxonomic knowledge be so limited?! Parasites aren’t the only poorly known British taxa, but I’ll be talking about issues relevant to parasite taxonomy today. In particular, Shaw and Hochberg (2001) focused on a specific group of parasites: parasitoid wasps.
So how many parasitoid wasp species are there in Britain? When this paper was published in 2001, ~6000 species were known. To put that in perspective, that’s ~1/4 of the total known British insect biodiversity! To reiterate, without counting all of the other parasitic insects (e.g., fleas, lice), at least one quarter of the insect biodiversity is parasitic. I say “at least” because…
“…it seems likely that across parasitic Hymenoptera as a whole our knowledge of what is in the British fauna may be about 30-40% incorrect, or possibly even more…it strongly suggests that parasitic Hymenoptera will eventually turn out to be an even larger fraction of the total British insect fauna.”
Oh dear. We know that there must be many more parasitoid wasp species in the world (and Britain, specifically) than we currently know about for three reasons. First, whenever people conduct new field surveys or look at museum collections of parasitoids, they find that only a small fraction of the collected species have been described before. Second, many specimens are later found to be incorrectly identified, because morphological identification of parasitoid wasps is hard. And third, even when people think that they have nailed their morphological identifications, they might later find that the “species” that they are referring to is really a “morphospecies” representing 2 or 20 or even more cryptic species that are indistinguishable morphologically. For instance, here’s a quote from Smith et al. (2014) – an ambitious study matching morphological identifications to DNA barcodes for hundreds of parasitoid wasp species – regarding just one of the many cryptic species complexes that they uncovered:
“This minute black wasp with a distinctive white wing stigma was thought to parasitize 32 species of ACG hesperiid caterpillars, but barcoding revealed 36 provisional species, each attacking one or a very few closely related species of caterpillars.”
Yikes! When I read that, I thought, “Wow, if I ever need to do anything with parasitoid wasps, I’m going to need to find a collaborator who specializes in parasitoid wasp taxonomy.” So let’s say that I do need hypothetical help with an important biodiversity conservation project in Britain. Would I be able to find a parasitoid wasp expert to collaborate with? According to Shaw and Hochberg, in 2001, there were ~6 such experts – you know, approximately one expert for each thousand wasp species. (No, no, it’s fine, writing this isn’t giving me anxiety.) That seems like a tiny number of people who are responsible for ¼ of Britain’s insects! But at least there are some parasitoid wasp experts in Britain. The situation is likely worse in most other regions, where natural history is likely less popular and species diversity might be greater.
We must also remember that even if we can associate a DNA barcode or morphological description with a species name, we do not necessarily “know” that species. I brought this up a few weeks ago after reading John Lawton’s autecology and extinction crisis essay, and Shaw and Hochberg (2001) were clearly concerned about the biodiversity listicle phenomenon, too:
“Other insects are in a frame in which parasitic Hymenoptera are not, because parasitic wasps, with a low proportion of exceptions, are mostly just names.”
Are you having feelings about parasitoid wasps now?
Of course, it is worth asking why we need to know more about parasitoid wasps. Research and conservation funding are limited, so why prioritize research regarding parasitoid wasps? I’ll give three possible reasons, but others could be suggested:
(1) If we are conserving biodiversity for its intrinsic value and/or because we believe that the most biodiverse or species-rich ecosystems are the best (for any given criteria), then we should perhaps prioritize research on the most species-rich and neglected taxa. Until we understand the most biodiverse taxa, we probably can’t maximize biodiversity conservation.
(2) Parasitoid wasps can be beneficial for humans. For instance, because parasitoid wasps tend to be highly host specific, they can be used as targeted biocontrols for agricultural pests. We’re talking serious economic worth. And given their documented effectiveness with controlling pests, it is likely that they play important roles in controlling populations of many other insect species that we don’t currently consider ‘pests’, but which might become problematic if they lost their parasitoid overlords. So maybe we should prioritize learning more about parasitoid wasps and conserving them to prevent potential economic losses.
(3) Parasitoid wasps might be especially vulnerable to extinction or co-extinction, so we might need to prioritize their conservation to prevent rapid biodiversity loss. As Shaw and Hochberg (2001) point out:
“The brief statement in the Insect Red Data Book (Shaw in Shirt (1987): 257-8) on parasitic wasps is to the effect that they must be considered among the most threatened of British insects, but that attempting a listing of endangered species would be quite hopeless in view of our poor knowledge. The message in this has, however, generally been as totally ignored as the parasitic wasps themselves.”
“..our parasitic Hymenoptera fauna…must – without any real doubt, given their high trophic level and characterizing levels of specialization and dependence – be happening at a rate that would surely be considered alarming, if only it could be noticed.”
Worryingly, that decline has been noticed outside of Britain:
“Therion (1976; 1981) reporting on the Ichneumonidae… fauna of Belgium, found that of the 122 species formally present 32 (26%) could not be found in a period of intensive collecting between 1950 and 1974/1979, with at least 30 further species (25%) showing major declines.”
After making cogent arguments for prioritizing parasitoid wasp conservation, Shaw and Hochberg (2001) provided several suggestions for improving those conservation efforts. One suggestion – including parasitoid wasps in Species Action Plans for better-known host species, like endangered butterflies – is something that I’ll come back to in my next parasite conservation post. For today, I’d just like to emphasize their number one suggestion:
“Nothing would do as much for the conservation of parasitic Hymenoptera as the provision of properly funded, career-length posts for alpha-taxonomists in major collection-building research institutions.”
Thank you, existing parasitoid wasp taxonomists! You rock. And I hope we can make and support many more scientists like you in the near future.
Shaw, M. R., and M. E. Hochberg. 2001. The Neglect of Parasitic Hymenoptera in Insect Conservation Strategies: The British Fauna as a Prime Example. Journal of Insect Conservation 5:253–263.
Smith, M. A., J. J. Rodriguez, J. B. Whitfield, A. R. Deans, D. H. Janzen, W. Hallwachs, and P. D. N. Hebert. 2008. Extreme diversity of tropical parasitoid wasps exposed by iterative integration of natural history, DNA barcoding, morphology, and collections. Proceedings of the National Academy of Sciences of the United States of America 105:12359–12364.