Citation Vacuums

In science, there’s a simple currency earned by important publications: citations by subsequent papers. Each citation gives credit, a small nod of recognition, a karma point, a feather in the cap. We are proud when our publications garner many citations. Citation count, however, is not a great metric of true quality or impact: all that glitters is not gold; all that is gold does not glitter. Counting citations sometimes credits authors with a greater part in advancing the field than they deserve, and fails to credit those who do.

I remember many years ago hearing David Swofford, the author of the widely-used PAUP program for analyzing evolutionary trees, grumbling about a paper just published. His complaint was that the paper’s “novel” concept wasn’t particularly novel — it was so obviously implicit in the literature’s ideas that none among the most theoretically astute biologists thought it was worth publishing in a standalone paper. And yet, the paper was published, and received attention precisely because no other paper had previously said that useful (though obvious) idea so directly.

Such gap in the literature is a “citation vacuum“, a region of “idea space” that is well within the current paradigm, but unoccupied by a citable paper. Over the years I’ve seen several vacuums exploited to the career benefit of their discoverers. We scientists like to cite compact, precise, and strong statements of an idea, and if none exists, then there is a vacuum in the literature waiting to be filled. It doesn’t matter if the idea is already understood by many, or if the idea is in fact already in the literature but in a long-forgotten paper or buried on page 9 of a software manual. It only matters that there is no obvious paper to cite, and if you write one, cha-ching, the citations come rolling in.

I’m reluctant to name names. Most authors who’ve written vacuum-filling papers probably don’t think of them as such, instead believing them highly novel, and I wouldn’t want to disturb their glory. I will mention one name, however — my own. My best cited paper is my 1997 paper “Gene Trees in Species Trees”. When I wrote it, I didn’t think of it cynically as a vacuum-filler, but in many ways, that’s what it was. It was a condensation of the Zeitgeist, gathering together and organizing ideas that probably were already, in large part, in the heads of the leaders of the field. It’s become a magnet for citations because it’s accessible and provides a compact citation for the field’s perspective. It’s a pedagogically useful paper, but I expect that it brought the median understanding in the field forward more than it informed those at the cutting edge.

So, go find a vacuum, publish, and profit*.

*To be clear: I’m not advocating that you withhold credit to your predecessors. Please, when filling a vacuum, look for and cite the papers that set up (or perhaps even mention) your idea. Treat your paper as a new attempt to synthesize and explain ideas already in the conversation of the field. Take credit for the clarity and thoroughness of your exposition, because those may be new, and will add value to the field.


Remembering Fred Wanless

Back in the old days (i.e. pre-web) it was hard to connect with others with common interests, at least when your interests were uncommon. By the time I was a graduate student, I’d been studying jumping spiders (salticids) for a decade, but had met precious few experts on my favourite spiders. Conferences were a rare chance to chat real-time with your far-away role models and comrades, and maybe find someone with whom you could speak at the speed of your excitement.

As a 28 year old, in 1986, I flew to Spain for my first International Congress of Arachnology (and my first visit to Europe), where I met Fred Wanless, an arachnologist at the British Museum of Natural History (now known pretentiously as The Natural History Museum). His publications on jumping spider systematics combined two strengths that were unique at the time: they examined salticid diversity broadly across phylogeny and geography, and they used cladistic logic to discuss evidence for jumping spider phylogeny. My recollection was that we met at a bar in Jaca; he was humble, uncomplicated, sincere. Talking to him was amazing — “Do you think Lapsias could be a spartaeine?” “Do you think an articulated embolus is an important character?” — and on and on. I left the evening feeling as if I had just flown through the forests of Endor on a speeder bike.

Fred died last month. We arachnologists hadn’t heard much from him for many years, because he had been forced in 1990 to stop studying spiders, told to study instead the more “relevant” nematodes. His departure from salticidology deprived us of a colleague and years of important publications (though no doubt the nematologists appreciated him). But his 1980s publications remain a cornerstone of our literature for the knowledge that they gained, and also for the model they provided: well illustrated, well argued, well organized. When I wrote a recent paper reviewing the phylogeny and classification of all jumping spiders, his papers were the first I went to, to pour over their data and interpretations.

I phoned Fred about 12 years ago to ask a question about a notable specimen I thought he might remember. His thoughts were far from jumping spiders, having drifted first to worms then to retirement projects. I told him how important his papers had become to us, and he was surprised — still humble and uncomplicated. We were lucky to have had him in our literature, and in our community.

Farewell to Mexico and #Mexigonus2017

It’s been almost three weeks since I got back from our Mexico jumping spider expedition, and I’ll give one last post to wrap up. The trip was a full of wonderful spiders and people and places. I have already thanked some of those who helped, but I’ll repeat and add others, who helped so much: For logistics, thank you Tila, Griselda, Ricardo, Gerardo, Arturo, Jorge, Juan Pedro, José Luis, Fernando, Alex, and Janette. For sharing your salticid expertise and experience, thank you Uriel, Łukasz, Dariana, Valentina and Ellen.

I should have known the trip was going to be a success before we hit the road. At the UNAM university bookstore, as we were stocking up at the start of the trip, there was this little souvenir puma — the mascot of UNAM — labelled as a biologist, with a spider on one arm and a beetle on the other. What better omen?

UNAM Puma biologist with spider and beetle

No, I didn’t buy the souvenir. Why, I don’t know. I have an aversion to (almost all) knick knacks.

Compact spider photo setup

The photos of beautiful spiders in my posts about our #Mexigonus2017 expedition were taken with a new camera, the first I’ve had in many years. For the previous 12 years I’d taken spider photos, tens of thousands of them, with a comical ancient Pentax Optio with a hand lens glued to it. Even though it’s old and low resolution (3 megapixel), it worked for me. In order to have a hand free for wrangling the spider, I need to be able to hold the camera in one hand and manipulate it easily. I also need to take photos of dozens of specimens each evening. Standard DSLRs are too awkward and heavy, so much so that I wouldn’t be able to take photos of all the species I want to photo, were I to use a big DSLR. I’d rather have low resolution photos than none at all, and for that reason I stuck with my tiny camera for many years.

A friend’s small mirrorless Olympus impressed me, and convinced me it was time to change, and I’m so glad I did. My new camera is an EM10-Mark II, with basic 60 mm macro lens and the standard TTL flash, which I mounted with polymer clay and zip ties as shown here. It’s a compact package I can manage mostly with one hand. It took me a while to figure out the settings (manual focus, etc.), but I’m very pleased with the results. The photos aren’t aesthetically as good as those of the current generation of good salticid photographers (I don’t use diffusers, etc.), and I could improve the arrangement to reduce shadows, but the photographs serve my purposes well. On one photo of a male that was hanging upside down, I could see the shape of the embolus of his genitalia. That’s good enough resolution for me!

Olympus EM10 — Mark II with Macro and flash, for taking spider photos.

Racing Stripes

People who know jumping spiders know that adult males of many species look different than females. Females are usually modestly coloured, but males may have bright colours they show to the females in elaborate dances. Some commonly-seen differences, however, don’t seem to relate to courtship. In many species, the males have distinctive black and white stripes, but the stripes are on their backs, which the females don’t see during the male’s courtship. Why do the males have stripes?

One of the most handsomely striped species I’ve ever seen is an undescribed Mexigonus from eastern Mexico. We caught it during our #Mexigonus2017 expedition at Sierra Gorda national park. Uriel calls this species “tuxedo” for the fancy suit the males wear. Here it is; on the left is the male, on the right the female.

Mexigonus “tuxedo”.

A similar male-female difference in stripes is seen in many other genera of jumping spiders, including some familiar in Canada such as Pelegrina, Eris, and Habronattus.

My best guess for the stripier pattern of males is that they move more than females. We have data from a few species of jumping spiders to indicate that males wander more, traversing a lot of territory in a day (looking for females?), while the females are relatively sedentary. An idea that’s been around for a while (e.g., look up Jackson, Ingram & Campbell 1976) is that what is good camouflage for an animal depends on how much it moves. If an animal sits still a lot, then it’s more cryptic if it’s mottled or spotted. If, on the other hand, an animal spends a lot of time moving forward, then longitudinal stripes can provide a disruptive visual effect that makes it harder for predators to see the moving animal. Hence, mobile males have stripes, homebody females not.

The Rainbow of Mexigonus

#Mexigonus2017 is over, and I’m back in Canada. I’m left with many memories of Mexico, strengthened friendships, great samples of new jumping spider species, and good data. As the first of a few retrospective posts here, I present The Rainbow of Mexigonus:

The Rainbow of Mexigonus

We saw the whole visible spectrum among the colours of Mexigonus. The red was intense; the orange was common; the green was delicate; the blue was stunning; the purple was unexpected. You’ll notice I didn’t mention yellow. For some reason, strong yellow is not obvious in Mexigonus adornments (except as a momentary flash in the metallic iridescence of the “quetzal” Mexigonus).

This is what the whole spiders look like, in the same sequence as the rainbow. The caption says who they are. You’ll notice that the multicoloured “quetzal” gets three appearances!

The cast of colours:

“quetzal” from El Triunfo “red moon” from Chicahuaxtla
“orange ghost” from San Jose del Pacifico “orange yellow” from Montebello
“big moss” from El Triunfo, female “yellow face” from San Fernando
“green ghost” from Humo Chico “quetzal” from El Triunfo
“blue legs” from Puerto Antonio “quetzal” from El Triunfo
“purple tomato” from Lachatao “purple tomato” from Lachatao

The second one down on the left side is worth mentioning — it’s an orange ghost! You may remember the green ghost from Humo Chico north of Ixtlan. When we headed south to the Sierra Madre del Sur and collected the “bell bottom pants“, we also found what we thought was the same green ghost species. But closer inspection showed it to be a different species — even fuzzier, without the white moustache, and with legs orange instead of green. Here is a better picture of him:

“Orange ghost” Mexigonus

Mexigonus is just so diverse, and almost all undiscovered.

The Weavings of Chicahuaxtla

In my first post about our #Mexigonus2017 expedition, I showed a photo of a brilliant red Mexigonus that was one of the inspirations of the study. We had found it in 1998, less than a kilometre northeast of San Andrés Chicahuaxtla, in Oaxaca. After our fulfilling time in Chiapas, we managed to arrange a visit to the area of Chicahuaxtla on the last day of the Oaxaca-Chiapas expedition, as we were driving back to Mexico City. I was filled with anticipation. I so much wanted to see the beautiful red “tomato” species again.

Early last Friday morning, we drove to Chicahuaxtla, where we met Amador Tello Rojas and Heladio Fernández Martinez. We weren’t able to go back to the exact site at which we’d found the red “tomato” beast in 1998, but Amador graciously allowed us to go to his family’s land, which was about 800 metres northwest of the 1998 site. The habitat was similar, oaks and pines in a fairly dry landscape.

We started to look on the ground and bushes beneath the oaks, and soon found a couple of small juvenile spiders that we thought were the red beast. But, we needed an adult male to be sure. After a long, frustrating search, a male finally fell onto my sheet. I was so excited — finally I’d see the red beast again! But, something was wrong. It should have had stout dark front legs; the one on my sheet had long delicate front legs with a little “feather” at the end. I got it in the vial, looked at it up close, and realized I had a brilliantly red spider, but different from the 1998 one. Here he is:

Mexigonus male from Chicahuaxtla

He’d certainly turn heads if he walked into a room.

Finding a new form so close to the red “tomato” beast confused me. It occupied what seemed to be the same microhabitat as the 1998 species, and it lived only 800 metres away. Do the two forms make contact between the two sites? They look closely related — do they hybridize? To add even more complexity, Jose Luis Castelo, a colleague who has done research on Mexigonus, noticed that our 1998 collection from Chicahuaxtla included a third fancy species, one that looked like our purple tomato. Three exquisite species of Mexigonus within one kilometre?

Are Chicahuaxtla’s mountains full of many beautiful Mexigonus, each occupying a small territory? Could it be that decorated Mexigonus exist as a pattern of many forms and colours spread across the landscape, evolved slowly over many generations, like the beautiful woven huipiles for which Chicahuaxtla is known?

In the end, we didn’t collect at the 1998 site, and so my desire to see the “tomato” species again remains unfulfilled. But, instead, we found a new and beautiful form. What we thought was a simple search has turned into a lot of questions about the diversity of ornamented Mexigonus in this mountain range.

The Call of the Quetzal

We had been collecting in the El Triunfo cloud forest for an hour or two, following the Costa trail south, when we arrived at the crest of the trail, at 2100 metres elevation, before it descends toward the Pacific coast. Up to that point, we had been finding only a single species of Mexigonus, a brown and creamy-yellow one:

Brown and yellow Mexigonus from El Triunfo, nice but not too exciting

Then, at about the same moment, Łukasz and I both found dark brown Mexigonus females that looked unfamiliar. We wondered: what do the males look like?

Unfamiliar dark brown Mexigonus female.

Male and females of many spider species look quite different. Male jumping spiders often bear fancy plumes and colours they show during dances to the females. And, of course, their genitalia are different. Because we taxonomists find many useful characters to distinguish species in their genitalia, we want to find both male and female specimens of each species in order to get a complete characterization.

But, I have to admit, arachnologists tend to be biased toward the males for scientific reasons — the species are easier to distinguish by the males — and for aesthetic reasons — the males are sometimes spectacularly ornamented. Seeing those two dark females was like hearing the call of an unfamiliar bird but not seeing it. We knew there was a kind of male in this forest, perhaps right in front of us, that we had never seen before. Would the males have muted colours, or would they burst resplendently from the forest like a colourful quetzal?

Knowing there were more out there, including the unseen males, we tried to guess their precise habitat. The females had been on small trees with some mosses and suspended dead leaves, and so we tried shaking various such trees over our sheets, seeing what fell out. After about an hour, we had found some juveniles, but not adult males. We were discouraged.

And then, he appeared. He fell on the beating sheet, his two long and furry front legs instantly marking him as a male. On the sheet, from above, he appeared as a nondescript grey.

Male of the grey-brown Mexigonus is finally found!

Once he was in the vial, I turned my hand lens on him.

Male of Mexigonus “quetzal”.

His face was red. The “fur” on his front legs shone a brilliant metallic green and blue and orange. He was a miniature quetzal. I was over the moon.

One of his most noticeable features is the wide fringe on the sides of his first legs, like the bell-bottomed spiders from Oaxaca. These fringes make his first legs appear very wide from above, but very narrow from the side:

Mexigonus “quetzal” male

Notice the blue glow from his right legs! Under some lights, the face positively glows orange-red:

Mexigonus “quetzal” male

(I’m sorry.  I can’t stop from adding more and more photos.)  Generally he hides his colours, but Uriel and I put him in front of a female and this is the pose the male took:

Mexigonus “quetzal” courtship pose. Wow.

In fact, the true quetzal, the bird that is both real and mythological, that gives proof to the magical realism that is Mexico, lives as well at El Triunfo. Is it the emblem of the park. We were told that we might see one were we to wake up early enough. We didn’t. We were fully satisfied with our little eight-legged quetzals.

We hiked down from El Triunfo on Wednesday, thankful for our time in the pristine, verdant wilderness, and for the park staff’s professional help. Our visit was supported generously and capably by Janette, Arcenio, and the rest of the El Triunfo team.

Of Foxes and Blue Beetles

Far in the south of Mexico, in Chiapas, is a set of mountains that parallel the Pacific coast. In the core of these mountains is El Triunfo national park, a hidden treasure that takes some work to get to. We drove to Jaltenango, took a 4×4 truck for a few hours to the village of Santa Rita at about 1200 metres elevation, then hiked up through the forest to a ridge at 2100 metres (our goods mule-carried), then down to the station nestled in a pastoral valley at 1950 metres. A bed, a rustic kitchen, and electricity. In a pristine cloud forest. Heaven.

Fox through the kitchen door, El Triunfo

Above is the view from the kitchen out onto the grounds. You’ll notice a grey fox. There were at least four of them, rather tame, hanging around whenever there was kitchen activity. Perhaps they had learned that food was occasionally dropped, or thrown.

The grounds around the station were cleared in part by the grazing mules. One of the first things we noticed were strange accumulations of shiny blue beetles on some small plants.

Blue beetles at El Triunfo

Here is a movie of the beetles; it’s quite a colourful sight. Perhaps mating congregations?

It took us a while to realize there was an ecological connection between the beetles and the foxes. Here are some animal feces deposited on the ground, about the right size for a fox, and with contents that make sense for foxes.

Mammal feces at El Triunfo

Notice the glints of blue. I felt like I’d walked into someone’s house and discovered there was more drama than visible at first.

Lagunas de Montebello

The geographical centre of my childhood is a point just across from Zephyr Island on the shore of Lake of Bays, in Ontario, Canada. There my family rented a cottage for a few weeks each summer throughout my childhood. It was a place of peace, of silver ripples at dusk, and a place of discovery, of salamanders and Sibianor and Maevia and Euophrys and Habronattus. My brother David and I never tired of its Nature.

A lake, surrounded by a green forest; the morning mist; a few people quietly working or sitting. A week ago I found myself in this familiar scene, filled with peace and an anticipation of discovery, at Lagunas de Montebello, a national park on the border with Guatemala. It’s at about 1500 metres elevation, a beautiful green cloud forest with epiphytes adorning many of the trees’ branches. After rousing from our cabins along the lake, we went to speak about our research plans to Odetta Cervantes Bieletto, director of the park, and her colleague Jose Alejandro Leon Mendoza (Alex). Alex, along with the park’s long-experienced Roberto, suggested a trail right near the headquarters. And so we headed out, beating sheets, sticks, and vials ready.

Within the first few minutes we got a surprise, the magical blue-legged Mexigonus! It turns out they were much more common than at the Puerto Antonio site in Oaxaca — at Montebello we got five males and a few females.

Montebello blue-legged Mexigonus

They might be a different species from that in Oaxaca, as the blue is muted, darker, and the face is red only above the eyes. We’ll answer the question of whether they are a different species once we get back to the lab.

We eventually found 5 species of Mexigonus there. Here are males of the other four:

4 other Mexigonus from Montebello

The top left and bottom right were new for our trip. We suspect that four of the five are new to science.

I’ll long remember the precious day at Montebello, not only for the new species of spiders, but also for its peaceful richness.