A Fearsome Little Delicatessen

We actually hit 15 degrees (F, that is) today -- at midnight! So here's a zoo shot, and a brief discussion:

Giant Whipscorpion (Mastigoproctus giganteus),
Cincinnati Zoo, Hamilton Co, OH 3/29/2012

This is a Giant Whipscorpion (Mastigoproctus giganteus), also known as a Vinegaroon. He's a fearsome critter, reaching about 3 inches in length. Despite the name Whipscorpion, they can't sting, although since they're predators of other arthropods, they can inflict a rather painful bite. They're found from Arizona to Oklahoma, and in Florida, and then south into Mexico, but since they're strictly nocturnal, (1) most people never see them.

So where does the name Vinegaroon come from? While they don't have a scorpion's venom, they do utilize a chemical weapon of a sort. When threatened, they can expel a fine mist composed of water and several organic acids. The primary component is actually acetic acid (85%), which is also the main acid in vinegar. (2) I've never encountered it, but I imagine that they must actually smell like a spring salad when they use the stuff. This isn't going to do more than irritate something the size of a human, and apparently it's most effective if it hits the eyes -- but then, the eyes are usually pretty close to the mouth, so I guess it works well enough.

I usually figure a good rule for handling critters is this: if you're not sure it's harmless, then assume it isn't! But this guy's fearsome appearance actually masks a relatively harmless reality. As Terry Pratchett, Ian Stewart, and Jack Cohen put it, Nature certainly knows how to lie. (3)

(1) Punzo, F. (2006). Types of shelter sites used by the giant whipscorpion Mastigoproctus giganteus (Arachnida, Uropygi) in a habitat characterized by hard adobe soils. Journal of Arachnology, 34(1), 266-268.

(2) Schmidt, J. O., Dani, F. R., Jones, G. R., & Morgan, E. D. (2000). Chemistry, ontogeny, and role of pygidial gland secretions of the vinegaroon< i> Mastigoproctus giganteus</i>(Arachnida: Uropygi). Journal of insect physiology, 46(4), 443-450.

(3) Pratchett, T., Stewart, I., and Cohen, J. (1999) The Science of Discworld. EBURY PRESS/Random House, London

Little Mice in the Fields

Here's a little guy from Tussey Mountain, shot a couple of years ago:

Southern Red-backed Vole (Myodes gapperi), Tussey Mountain Hawkwatch,
Central Co., PA 3/27/2012

This is a Southern Red-backed Vole (Myodes gapperi), one of three species of Myodes and 26 species of vole to occur in North America. In any one area, there may be 5 or 6 species coexisting. When this happens, we expect to see some form of ecological separation between species, and the voles don't disappoint. For instance, in aspen parkland in Saskatchewan, this guy was found in aspen groves, whereas Meadow Voles (Microtus pennsylvanicus) were found in the surrounding grasslands. (1) Similarly, in Yellowstone NP, Mountain Voles (Microtus montanus) were found in open meadows, and Long-tailed Voles (Microtus longicaudus) in the ecotones between meadows and forests. (2)

In both cases, one of the two species was willing to use both habitats -- M. pennsylvanicus were found in aspen groves in Saskatchewan, (1) and M. longicaudus moved out into Yellowstone meadows when M. montanus were removed. (2) The opposite movements didn't occur, which indicates that one species was excluding the other from a preferred habitat, rather than each species living in the habitat it's best adapted to. Interestingly, in Saskatchewan, M. pennsylvanicus was found to use aspen parkland (M. gapperi's habitat) in the winter, whereas in Manitoba, the reverse was found to be true -- in the winter, M. gapperi moved into the open meadows preferred by M. pennsylvanicus. (3) These authors suggest that breeding voles are more aggressive and actively exclude the other species during the breeding season, but are less so during the winter. An alternative explanation may well be that populations are lower during the winter, and so competition is reduced.

These fine-scale habitat preferences can become very important when habitats change. European Field Voles (Microtus agrestis) were shown to drop significantly in abundance when habitat corridors (the unplowed margins of agricultural fields) became too narrow to support them. (4) If climate change, shifts in wildfire management, etc. were to affect the distribution of meadows and woodlands in an area, we would not only expect to see shifts in vole populations, but we would expect to see a similar threshold effect. This sort of non-linear reaction to habitat loss should be a distinct concern for wildlife managers everywhere.

Voles are fascinating little critters, even if we rarely get such a look. (This is the only species for which I have good photos of a wild, living individual.) With small home ranges and short reproductive times, they can provide a wonderful window into evolution and ecology.


(1) Morris, R. D. (1969). Competitive exclusion between Microtus and Clethrionomys in the aspen parkland of Saskatchewan. Journal of Mammalogy, 291-301.

(2) Anich, P. S., & Hadly, E. A. (2013). Asymmetrical Competition between Microtus montanus and Microtus longicaudus in the Greater Yellowstone Ecosystem. The American Midland Naturalist, 170(2), 274-286.

(3) Iverson, S. L., & Turner, B. N. (1972). Winter coexistence of Clethrionomys gapperi and Microtus pennsylvanicus in a grassland habitat. American Midland Naturalist, 440-445.

(4) Renwick, A. R., & Lambin, X. (2011). Abundance thresholds and the underlying ecological processes: Field voles Microtus agrestis in a fragmented landscape. Agriculture, Ecosystems & Environment, 144(1), 364-369.

A Sinister Collection?

If you've never dared to look closely at wasps, here's a bit of what you've been missing:

Euodynerus castigatus, Illinois Beach SP, Lake Co., IL  6/7/2012

Stenodynerus oculeus, Illinois Beach SP, Lake Co., IL  7/21/2013

These two species are in the family Vespidae, which also includes the familiar Paper Wasps, Yellowjackets, and Hornets.

Great Golden Digger Wasp (Sphex ichneumoneus),
Illinois Beach SP, Lake Co., IL 9/16/2012

This one's in the family Sphecidae.

Dolichomitus irritator, Illinois Beach SP, Lake Co., IL  11/11/2011

Protichneumon grandis, Necedah NWR,
Juneau Co., WI 8/10/2013

And these two are in the most diverse family in the order, the Ichneumonidae. (Estimates for the number of species worldwide range from 60,000 up to 100,000!)

These are just a few of the 18,000 species of hymenopterans estimated to occur in North America. (1) Given that most of them are nectar feeders, and clearly compete with each other, how do so many species manage to coexist?

Well, it turns out that many of them are only nectar feeders as adults. Most of the wasps are parasitoids -- as larvae, they eat insects or other arthropods that their mother provides, first paralyzing them with her sting. In some cases, those other arthropods can include spiders, even large ones! Many wasps are extremely host-specific (i.e. they only attack one or a few critters) as well, and since there's so many other arthropods, there's lots of possible niches to fill. (2)

Their use of pheromones as sexual signals means that two species can coexist without any obvious morphological differences between them, and it's probably not surprising that we find many cryptic species complexes in the smaller wasps. In many cases, what was at first thought to be a single, generalist species has turned out to be multiple, nearly identical specialist species. (3)

I find all this stuff fascinating on it's own -- the richness of our natural world never ceases to amaze, and it just gets better as you look closer. But there are practical advantages to learning about diversity in these wasps: many of them are used for biological control of pest insects, and knowing what's what with the wasps and their hosts can be the difference between an effective control program and a total waste of time and money. (4)

The next time you get the chance to stop and smell the roses, look out for little visitors, and take a moment to think about how delightfully intricate the world can be!

(1) http://bugguide.net/node/view/59

(2) Hawkins, B. A., LaSalle, J., & Gauld, I. D. (1993). Refuges, host population dynamics and the genesis of parasitoid diversity. Hymenoptera and Biodiversity., 235-256.

(3) Bickford, D., Lohman, D. J., Sodhi, N. S., Ng, P. K., Meier, R., Winker, K., ... & Das, I. (2007). Cryptic species as a window on diversity and conservation.Trends in Ecology & Evolution, 22(3), 148-155.

(4) Rosen, D. (1978). The importance of cryptic species and specific identifications as related to biological control. In Beltsville symposia in agricultural research.(2). Biosystematics in agriculture. Invited papers presented at a symposium held May 8-11, 1977 at the Beltsville Agricultural Research Center (BARC), Beltsville, Maryland 20705. (pp. 23-35). Allanheld, Osmun & Co. Inc..

Fairy Umbrellas

Here's a familiar little critter:

Umbrella Inky-cap (Parasola plicatilis), Ryerson FP, Lake Co, IL 9/29/2011

Well, it's familiar if you like looking real closely at lawns. This is an Umbrella Inky-Cap (Parasola plicatilis), a common lawn mushroom in much of the country.

What we call a mushroom is actually just the reproductive structure of a fungus (of some fungi, at least). The majority of the fungus is a mass of thread-like cells called hyphae that extend, in this case, into the soil. They're rather hard to distinguish from each other this way, of course, so we generally use the mushroom characteristics to identify the fungi. Modern DNA and chemical analyses are proving that to be a good way to grossly underestimate fungal diversity, though. (1)

But why do the mushrooms differ so widely? This is a difficult question -- all a mushroom should have to do, it seems, is to disperse as many spores as it can as widely as possible without being eaten first. There seems to be an awful lot of structural diversity for such simple functions. Bright colors may well be aposomatic, but what is the functional significance of a scaly versus a smooth top to a mushroom, when the spores are produced on the underside?

Nagy, et al. have looked at this question with regards to the Parasola shown above, as well as related species. This one, as well as many others in the family Psathyrellaceae, exhibit a phenomenon known as deliquescence -- the gills on the underside dissolve into an inky liquid as the spores mature. (Hence the name Inky-caps.) Using the family and the evolution of deliquescence as a platform for testing recently developed statistical techniques for phylogenetic analysis, they found multiple origins for this trait, and found no support for its loss in any lineage. (2) Apparently deliquescence produces some sort of notable advantage for those lineages that develop it. They also found that certain structures on these mushrooms appear to have co-evolved with the emergence of deliquescence, suggesting some form of functional significance to them as well. (3) They suggest that it's a way of avoiding desiccation of the spores, which is an interesting hypothesis that appears to need testing. Whether or not avoiding desiccation is the primary function, this process appears to have driven a rapid adaptive radiation in the family, along with some correlated structures that serve to protect the spores from predators. (4)

Parasola isn't, as far as we know, edible, and it doesn't cause infections. It doesn't appear to be poisonous, or damage anything we find useful. In the words of Leopold, "Just a small creature that does a small job quickly and well."



(1) Nagy, L. G., Desjardin, D. E., Vágvölgyi, C., Kemp, R., & Papp, T. (2013). Phylogenetic analyses of Coprinopsis sections Lanatuli and Atramentarii identify multiple species within morphologically defined taxa. Mycologia, 105(1), 112-124.

(2) Nagy, L. G., Urban, A., Örstadius, L., Papp, T., Larsson, E., & Vágvölgyi, C. (2010). The evolution of autodigestion in the mushroom family Psathyrellaceae (Agaricales) inferred from Maximum Likelihood and Bayesian methods.Molecular phylogenetics and evolution, 57(3), 1037-1048.

(3) Nagy, L. G., Walther, G., Hazi, J. U. D. I. T., Vágvölgyi, C., & Papp, T. (2011). Understanding the evolutionary processes of fungal fruiting bodies: correlated evolution and divergence times in the Psathyrellaceae. Systematic biology,60(3), 303-317.

(4) Nagy, L. G., Hazi, J. U. D. I. T., Szappanos, B., Kocsubé, S., Bálint, B., Rakhely, G., ... & Papp, T. (2012). The evolution of defense mechanisms correlate with the explosive diversification of autodigesting Coprinellus mushrooms (Agaricales, Fungi). Systematic biology, 61(4), 595-607.

Gulls are Hard!

In honor of next week's return to Arctic conditions:

Kumlien's Gull (Larus glaucoides kumlieni),
North Point Marina, Lake Co, IL 2/16/2013

This is a Kumlien's Gull (Larus glaucoides kumlieni).

Thayer's Gull (Larus thayeri),
Waukegan Beach, Lake Co, IL 2/23/2014

This is a Thayer's Gull (L thayeri). At least according to the AOU. According to the British, it's another Iceland Gull (L glaucoides thayeri). And if we follow the precedent we see in other gulls, the first one isn't an Iceland Gull at all, it's a hybrid (L. glaucoides X thayeri)!

It's all a bit of a mess, really. So shall we dive in?

The AOU considered Thayer's Gull to be a subspecies of Herring Gull until 1983, at which point it was split into a separate species. Kumlien's (now thought to be our subsp. of Iceland) was considered a distinct species until 1957, when it was lumped with Iceland. Today, Thayer's and Kumlien's are known to interbreed in parts of northern Canada. (1) McGowan & Kitchener, reviewing historical records of the two, argued that Kumlien's is a hybrid swarm that originated when Thayer's expanded their range east into that of the nominate Iceland Gull (L. g. glaucoides). (2)

So what is the status of these forms? They all interbreed, apparently, which suggest that the British are right, and they're all the same species, right? Well, not necessarily. Hybrids between different species do occur, as this guy from last year's Gull Frolic demonstrates:

Great Black-backed X Herring Gull (Larus marinus X argentatus smithsonianus)
North Point Marina, Lake Co, IL 2/16/2013

As far as we could tell, this is a Herring X Great-Black-backed hybrid. And some birds hybridize extensively without being lumped. Like this guy:

Glaucous-winged Gull (Larus glaucescens),
Resurrection Bay, AK 8/5/2012

Meet Larus glaucescens, the Glaucous-winged Gull. These guys are famous for their, shall we say, indiscreet ways? They're best known for extensive hybridization with Western Gulls (L. occidentalis) in Washington State, but they form mixed colonies of mostly hybrids with whatever large gulls they overlap with. For instance, this guy:

Glaucous-winged X Herring Gull (Larus glaucescens X argentatus smithsonianus)
Potter Marsh, Anchorage, AK 8/3/2012

Photographed at Potter Marsh just south of Anchorage, this appears to be a Herring X Glaucous-winged hybrid, the most common large gull in and around Anchorage.

Despite all this, we still consider Glaucous-winged to be a good species, and indeed in areas away from the hybrid swarms they seem to fit the criteria.

What does this mean for Kumlien's Gull? If McGowan & Kitchener are right, then kumlieni resulted from the eastward movement of Thayer's displacing Iceland, with a fairly extensive hybrid zone forming in eastern Canada (although farther north, they failed to produce a hybrid zone, instead replacing Iceland completely). With Glaucous-winged, we don't consider a hybrid swarm to be a separate subspecies, and we clearly don't consider it evidence for sympatry (if we did that, we'd be left with about three species of large gull -- which is two more than some authors have called for!). So, should we Chicago birders keep looking for Iceland's, or should we prepare to give up our beloved Thayer's Gulls as Icelands? Or perhaps we'll start calling kumlieni a hybrid swarm, similar to the Olympic Gulls on the west coast -- if we follow the Glaucous-winged example that seems the sensible course.

Surprisingly, Gay, et al., in a phylogeny based on mtDNA, found that Thayer's clustered with Glaucous-winged, as part of a large Arctic clade that includes Iceland. In fact, they were unable to distinguish Thayer's from Glaucous-winged. (3) On the other hand, they appear to have American Herring Gull as a sister species to California Gull, which suggests that mtDNA may not be the best method for determining phylogenies of lineages that hybridize this freely.

These large gulls can be maddening to the birding community. (Online discussions about odd or out-of-place gulls can drag on for years without a resolution. Check out Old One-Foot as an example, or last year's possible Slaty-backed Gull in Connecticut). For the biologist, they're a reminder that critter's don't have to follow the nice, neat scripts we write for them. They live their lives, it's up to us to write a story that fits.

(1) Gaston, A. J., & Decker, R. 1985. Interbreeding of Thayer’s Gull Larus thayeri and Kumlien’s Gull
Larus glaucoides kumlieni on Southampton Island, Northwest Territories. Can. Field. Nat. 99:
257-259.

(2) McGowan, R. Y., & Kitchener, A. C. (2001). Historical and taxonomic review of the Iceland Gull Larus glaucoides complex. British Birds, 94, 191-195.

(3) Gay, L., Bell, D. A., & Crochet, P. A. (2005). Additional data on mitochondrial DNA of North American large gull taxa. The Auk, 122(2), 684-688.

Two Little Drops of Sunshine

Here's a couple of familiar sights, here in Lake County (though not quite yet):

Clouded Sulphur (Colias philodice), Illinois Beach SP, 10/4/2011

Orange Sulphur (Colias eurytheme), Illinois Beach SP, 7/11/2012

The first shot's a Clouded Sulphur (Colias philodice) and the second one is an Orange Sulfur (C. eurytheme). Caterpillars of both feed on legumes, both native ones and introduced things like Vetch and, especially, Alfalfa. This last host means that they can be serious pests, and as a result, we know quite a bit about them.

These two species are very closely related, and hybridize quite a bit.  Even without hybridization, they both vary so much in color that identification in the field is often impossible. (The Illinois Butterfly Monitoring Network combines the two species for it's surveys, in fact.) In addition to variation in melanin concentrations and the amount of orange in the wing, females of both species have a normal yellow/orange morph and a white one. Yet despite all this, they manage to remain distinct. Clearly, they're using something more than the color and pattern. Turns out they're using pheromones. (This shouldn't be a surprise if you're into bugs.) (1)

But where does this color variation come from? Males do use wing color in mate choice, which normally reduces this sort of variation, and if hybridization isn't sufficient to drive the populations together, it must not be driving that variation. Ellers & Boggs found that in C. philodice populations in Colorado, male mate choice for brighter females was countered by natural selection for darker wings at higher elevations. Since the populations aren't actually isolated, this has the effect of maintaining variation throughout the population. (2)

In addition to this, however, Sappington & Taylor found that sexual selection by itself can maintain this variation. They studied the chemical makeup of the pheromones in C. eurytheme, and found it to be surprisingly variable. They then examined female mate preferences for different mixes, and found that white morph females prefer one form of the pheromones, while yellow morph females prefer another. (3) I haven't found any similar work on C. philodice, but given how closely related they are, it wouldn't be a surprise to find something similar going on with them.

The nature of variation in a population and how it changes over time is the essence of evolutionary biology. Whenever our days finally warm up and allow these little bits of sunshine out, stop for a moment and think about them as living critters, making their way through history the best that they can.

(1) TAYLOR, O. R. (1973). Reproductive isolation in Colias eurytheme and C. philodice (Lepidoptera: Pieridae): use of olfaction in mate selection. Annals of the Entomological Society of America, 66(3), 621-626.

(2) Ellers, J., & Boggs, C. L. (2003). The evolution of wing color: male mate choice opposes adaptive wing color divergence in Colias butterflies. Evolution, 57(5), 1100-1106.

(3) Sappington, T. W., & Taylor, O. R. (1990). Disruptive sexual selection in Colias eurytheme butterflies. Proceedings of the National Academy of Sciences,87(16), 6132-6135.

Fishing in a Sea of Time

Here's a quartet of odd-looking critters:

Longnose Gar (Lepisosteus osseus) and Bowfin (Amia calvia),
Milwaukee County Zoo, WI  1/15/2012

Australian Lungfish (Neoceratodus forsteri), Shedd Aquarium, Chicago, IL
1/20/2013

Atlantic Lumpfish (Cyclopterus lumpus), Denver Aquarium, CO
12/30/2013

That first shot includes a Longnose Gar (Lepisosteus osseus),  and a Bowfin (Amia calvia). Both are often considered 'primitive' fish, which really means that structurally they resemble early fishes considerably more than more 'advanced' fish do. In this case, they are both non-teleost Actinopterygii. (Actinopterygii are the ray-finned fishes; teleosts are the largest modern group of them, including most of what we now call fish.) Bowfin are actually the sister group of the teleosts, (1), branching off sometime in the late Permian or early Triassic. The ancestors of gars would have split somewhat earlier, but recognizable fossils of gars only date from the late Cretaceous, so even by that standard they aren't especially 'primitive'.

The second shot shows an Australian Lungfish (Neoceratodus forsteri). Despite looking fish-like in every way, this one's more closely related to you or I than to any of these (or any) other fish! It's in the Sarcopterygii, which today includes 6 species of Lungfish, 2 species of Coelecanth, and the tetrapods -- amphibians, reptiles, birds and mammals! Their last common ancestor with us would have lived around 380 million years ago, while they last shared a relative with these other fish over 400 million years ago. And after all that long time, only 8 species are still recognizable as fish. So if we are going to call one of our fish 'primitive', it's gotta be this one.

But what's up with that last shot? This is an Atlantic Lumpfish (Cyclopterus lumpus). It's in the family Cyclopteridae. The family is a small one, with only 27 species, most of which live in the North Pacific and all of which require cold water. Small family, limited range, and weird appearance -- another 'primitive' fish, right?

Not at all! The Cyclopteridae falls in the order Scorpaeniformes, which fits somehow into the Percomorpha. Other members of the Percomorpha include seahorses, guppies, tuna, and bass -- hardly a primitive group at all, and the Lumpfish is right at home there.

Sorting this all out is a difficult task. All we have are some scattered fossils, and a bunch of critters that we view as bundles of traits. But those traits can be the result of convergence, or they can be tightly correlated with each other. Sometimes it's hard just to decide what makes up a trait. And it's important that we're picking traits that vary more between groups than within, or the results won't make much sense. In the face of all this, I find it remarkable how much we have managed to figure out, and the pictures that we're seeing emerge as a result of this are awe-inspiring: imagine how many moments of drama and intrigue must have played out, with millions of critters chasing each other through an ocean of changes for 400 million years!

I used the term primitive, but I hope this selection illustrates the danger in using that term for a modern, living, breathing critter. Bowfins and Australian Lungfish aren't primitive, they're very much modern animals, surviving in a world that's just as difficult and dangerous for a fish today as it was 400 million years ago.

(1) http://www.tolweb.org/

It's a bird, it's a bat, its...?

Here's a critter you don't see everyday:

Dsungaripterus weii, Cincinnati Zoo, OH, 3/29/2012

Dsungaripterus weii, Cincinnati Zoo, OH, 3/29/2012

This, as far as I can tell*, is Dsungaripterus weii, a Dsungaripterid pterosaur from the early Cretaceous. This particular one hangs out in the bird house at the Cincinnati Zoo, but in life, it flew around what is now western China.

As a birder, I have to admit, I find pterosaurs fascinating -- not only were they the first chordates to develop flight, but they showed a truly amazing range of ecological adaptations, from small creatures that may have behaved like Whip-poor-wills (Anurognathids, described by Mark Whitton as Muppet-faced) to truly gigantic Azdarchids, including Quetzelcoatlus, with 10.5 meter (That's 35 feet!) wingspans, thought to be the largest creatures ever to laugh at Earth's attempts at gravity. (1) 

They also help provide a useful lesson in evolution -- I mentioned that they were the first chordates to develop flight. Well, here's an example of the second group:

Herring Gull (Larus argentatus)
Lake County Fairgrounds, 2/14/2014

And here's one from the third group:

Straw-colored Fruit Bat (Eidolon helvum), Omaha Zoo, NE, 12/30/2012

Obviously, the second one is a bird (a Herring Gull (Larus argentatus) to be precise), and the third one is a bat (a Straw-colored Fruit Bat (Eidolon helvum)). Now, clearly, for a creature to fly, it needs some sort of a wing. Ancestral tetrapods had four limbs (hence the name tetrapod!), and while species have lost some, no species of tetrapod has developed a fifth (or sixth, etc.) limb. So if we're going to grow wings, they're going to have to be variations on one of the four. All three groups developed wings using the forelimbs, although bats and pterosaurs both connected their wings to their legs to help with control. Three out of three isn't exactly a statistically significant sample, but the physics strongly suggest that hind limb wings would be very difficult to use, so it probably isn't a coincidence.

But look at those wings! The bat does things, I would think, the most sensibly. The fingers elongated, and the skin between them no longer dies back during development, leaving them with extensive webbing. You can see the long fingers in this shot. The pterosaur did something a bit funny - only one finger elongated! The webbing extends back from that finger to the leg bones, but all of the bony structure of the wing is at the front. (Soft-part fossils suggest that there were tendons running through the membrane, so it was well supported.). Birds, on the other hand, basically got rid of their fingers! Looking at that bird's wing, the only place where the feathers are concealing bone is the dark part (the way the color delineates it is a quirk of this species and plumage, not a general characteristic). The joint halfway out that looks like the elbow is actually the wrist, and the hand bones beyond it are almost entirely fused - think about the end of the chicken wings you may have had for lunch.

So we have three lineages, each of them very successful. (Pterosaurs are extinct, yes, but they lasted 150 million years or so first.) They show some definite convergences (in addition to wings at the front, they all show compact bodies, high shoulder joints, and several other adaptations to flight) where physics leaves no choice, but each one approached the problem with a different historical background, a different anatomy, and a different set of ecological needs (well, I assume that that last one is true, anyways). Wonder of wonders, they achieved a common goal in three very different ways!

Evolution works like this. Where physics, chemistry, and ecology provide simple constraints, we should expect convergence. But wherever there's room for experimentation, critters are going to show the results.

*Corrections welcome, of course! 

(1) Mark P. Witton. (2013) Pterosaurs: Natural History, Evolution, Anatomy. Princeton, NJ: Princeton University Press.

The Biggest Little Frond in the Sea

Talking protists in class these days, so here's the only one I have photos of:

Giant Kelp (Macrocystis pyrifera), Seward, AK  8/3/2012

For the most part, protists are small critters, typically microscopic. This, on the other hand, is Pacific Giant Kelp (Macrocystis pyrifera), washed up on the beach at Seward, Alaska. It can reach 45 meters long (that's ~150 ft!), not bad for something we call a protist. Since it grows in dense stands (often called forests), it actually affects light conditions, (1) water flow, and nutrient levels in the surrounding water, (2) making it a crucial part of an ecosystem that supports many other species, from young fish to Leopard Sharks (Triakis semifasciata) and Sea Otters (Enhydra lutra). When Kelp is removed, communities of smaller algae change, often dramatically, (3) although the extent of the changes does appear to vary with the specific composition of those communities. (4) Even after it washes up on shore, kelp supports an interesting fauna of little critters. (5) Losing this species means major changes in coastal Pacific waters, including the loss of important game and food fishes. And a study from 1998 of Orca (Orcinus orca) predation on Sea Otters suggests that overfishing of salmon, by a very interesting chain of events, has produced that very result in the Pacific Northwest. (6) Orcas that once relied on salmon have been forced to prey on sea otters, resulting in a decline in otter populations. Otters like to eat sea urchins, so we see more of them. And sea urchins (some of them, at least) feed on kelp holdfasts (the bottom part, where a bottom-dwelling sea urchin could reach). So an increase in urchins produces a decrease in kelp, all because of overfishing of salmon.

Orca (Orcinus orca), Resurrection Bay, AK, 8/4/2012

Sea Otter (Enhydra lutris), Resurrection Bay, AK 8/4/2012

Protists are sometimes called a "wastebasket" group. As I tell my students, they're all the eukaryotes that didn't get big or interesting enough to call their own kingdom. But Giant Kelp is clearly both big and interesting -- guess I'll have to amend that.

(1) Gerard, V. A. (1984). The light environment in a giant kelp forest: influence of Macrocystis pyrifera on spatial and temporal variability. Marine Biology, 84(2), 189-195.

(2) Gerard, V. A. (1982). In situ water motion and nutrient uptake by the giant kelp Macrocystis pyrifera. Marine biology, 69(1), 51-54.

(3) Foster, M. S. (1975). Regulation of algal community development in a Macrocystis pyrifera forest. Marine biology, 32(4), 331-342.

(4) Santelices, B., & Ojeda, F. P. (1984). Effects of canopy removal on the understory algal community structure of coastal forests of Macrocystis pyrifera from southern South America. Marine ecology progress series. Oldendorf, 14(2), 165-173.

(5) Inglis, G. (1989). The colonisation and degradation of stranded< i> Macrocystis pyrifera</i>(L.) C. Ag. by the macrofauna of a New Zealand sandy beach.Journal of Experimental Marine Biology and Ecology, 125(3), 203-217. 

(6) Estes, J. A., Tinker, M. T., Williams, T. M., & Doak, D. F. (1998). Killer whale predation on sea otters linking oceanic and nearshore ecosystems. Science,282(5388), 473-476.

"Freedom from want and fear."

Our first thaw in 4 weeks, so here's a shot in honor of melting snow everywhere:

Rough-legged Hawk (Buteo lagopus),
Rollins Savanna FP, Lake Co, IL 1/29/2014

Along with a quote from one of my favorite authors, Aldo Leopold:

"The rough-leg has no opinion why grass grows, but he is well aware that snow melts in order that hawks may again catch mice. He came down out of the Arctic in the hope of thaws, for to him a thaw means freedom from want and fear." (1)

Leopold was a keen observer, which explains why come November hawkwatchers across the US start studying maps of snow cover in Canada. Even once they reach their wintering grounds, snow plays an important part in their ecology. Sonerud found that Rough-legs tend to winter in snow free areas where possible, (2) and Schnell found that when snow cover exceeds 1 inch, they tend to cluster along roads. (3)

Mice, of course, are easier to catch when there's no snow, since they can tunnel underneath it where they can't be seen. (The temperature is often warmer under an insulating blanket of snow as well.) On the other hand, wolves have a much easier time hunting deer in deep snow. (4) By the same token, while many of us in Chicago were luxuriating in the warmer weather, skiers and snowmobilers were facing the end of their season. Whether it's hawks, mice, or us, tomorrow's forecast is as much a mirror as it is a picture.

(1) Leopold, A. (1949). A Sand County Almanac and Sketches Here and There. New York: Oxford University Press.

(2) Sonerud, G. A. (1986). Effect of snow cover on seasonal changes in diet, habitat, and regional distribution of raptors that prey on small mammals in boreal zones of Fennoscandia. Ecography, 9(1), 33-47.

(3) Schnell, G. D. (1968). Differential habitat utilization by wintering Rough-legged and Red-tailed Hawks. Condor, 70(4), 373-377.

(4) Huggard, D. J. (1993). Effect of snow depth on predation and scavenging by gray wolves. The Journal of wildlife management, 382-388.

What is a Panda, really?

A whole day of snow today, so here's a shot of a critter that knows a thing or two about the subject:

Red Panda (Ailurus fulgens),
Lincoln Park Zoo, Chicago, IL 11/30/2013

This, of course, is a Red Panda*, (Ailurus fulgens). They are residents of China and the eastern Himalayan countries, and are currently listed as vulnerable, with decreasing populations throughout their range.

Red Pandas provide a fascinating lesson in how our views towards classification have changed over the years. It's been called a Raccoon (family Procyonidae, otherwise only found in the New World), an aberrant bear (family Ursidae), or a member of a family of Pandas (Ailuripodidae, including it and the Giant Panda, Ailuropoda melanoleuca). The idea, of course, is that we know that we have this critter, now we need to figure out what it really is -- which means finding which taxonomic folder it belongs in and stuffing it in there.

Modern DNA analysis has done wonders for our taxonomic efforts, but even before they became widespread, a more modern view of taxonomy had started to take effect. Called cladistics, it attempts to apply an explicitly evolutionary model to whatever critters we're working on, defining a taxonomic group purely on common ancestry. Ideally, a name is applied to a group if and only if that group includes all of the descendants from a particular ancestor, sometimes dubbed the LCA (from last common ancestor, of course). This sort of group, formally called a "clade", is described as monophyletic. Leaving out descendants (say, non-flying mammals) would produce a paraphyletic group, and adding unrelated species (say, fish and whales) would produce a  polyphyletic group.

The Red Panda's lineage apparently split from the LCA of weasels and raccoons around 39 million years ago, about 7 million years before the weasels and raccoons parted ways. (1) Since we consider the weasels and raccoons to be separate families, there isn't anywhere to put the Red Panda to keep the groups monophyletic, so it gets its own family (Ailuridae). Instead of figuring out what the Panda "really is", we've figured out what the evolutionary history behind it "really is" and then shaped our groups, and names, to fit.

This leads some authors to label the Red Panda a "living fossil", which is a truly oxymoronic name: fossils are defined as traces of living things more than 10,000 years old. But does it even apply in this case? Yes, this group split off quite early, but obviously it's still around today. And it turns out that the family used to be much more important -- there are quite a few fossil species, ranging from China to England, and recent finds in several parts of North America. (2) So what we have is not a single lineage that has somehow survived till now, but a widespread group that is only recently down to one species. (Actually, most 'living fossils' fit this description, I guess.)

The loss of those other species suggests that the Red Panda is doomed to eventual extinction -- but that actually describes every creature on Earth. For now, we're all vibrantly, exuberantly alive, and I can't help but feel that exuberance just a bit more when I'm watching this shining little critter.

*A Red Panda actually played an important, if unsung, role in a couple of recent movies. If you've ever seen Kung Fu Panda and wondered what sort of animal Master Shifu was, well, he's a Red Panda!

(1) http://www.onezoom.org/mammals.htm

(2) Naish, Darrin (2008-04-05). "The once mighty red panda empire". Tetrapod Zoology. Retrieved 9 January 2010.

The Original Seedless Plants

A long walk along the lakefront produced nothing interesting except snow, so here's another hope for warmer weather soon:

Sphagnum Moss, Volo Bog, Lake Co, IL 7/16/2003

This is Sphagnum Moss from Volo Bog.

Liverworts, Devil's Lake State Park, Sauk Co, WI 8/9/2013

These little plants are liverworts, from Devil's Lake State Park, Sauk Co,  WI.

Ground-Pine (Lycopodium clavatum),
Ridges Sanctuary, Door Co, WI 5/29/2012

This one is a Ground-Pine (Lycopodium clavatum) from The Ridges Sanctuary, Door County, WI.

All of these share an interesting trait: They don't produce seeds! Instead, they reproduce by spores, which are smaller, much more numerous, and carry almost no start-up capital with them. They share another interesting trait as well, but this one will take a bit of explanation.

You, presumably, are a diploid organism. That means you carry two copies of each chromosome, and therefore of each gene. (That would be one copy from Dad and one from Mom, of course.) In humans, aside from the sex chromosomes, having too many or two few chromosomes causes serious problems. (Mostly fatal ones, in fact.) We (like most animals) only have a very short haploid phase, in our case as sperm and eggs.

Plants are different -- not only can they tolerate extra chromosomes much better than we can, they actually develop as both haploid and diploid organisms, one after the other. In fact, all of the plants in those photos were haploid! (The brown part of the Ground Pine is diploid.) In these plants, the haploid phase is dominant, while the diploid phase is typically small and completely dependent upon the haploid phase. By contrast, in flowering plants and pines, the dominant phase is diploid, while the haploid phase does develop into a multicellular structure it does so inside the cones or flowers.

The dominance of diploid phases in "advanced" plants and animals makes it easy to assume that there is some advantage to being diploid (1) , but is that really true? Anderson et al. found that haploid populations of yeast evolved resistance to anti-fungal agents considerably faster than diploid populations, presumably because recessive mutations in diploid populations were masked and therefore invisible to selective pressure. (2) On the other hand, being diploid means that a) heterozygote advantage is possible, and b) any deleterious recessive mutations are tolerable. The flip side of that, of course, is that those same mutations can be inherited, whereas in a haploid population, any deleterious mutation is immediately selected out of the population. This sounds rather callous, but it's the way that wild populations actually work - if your infant mortality rate is going to be high, you can afford a very high level of deleterious mutations, since those individuals were probably going to die anyways. So it turns out that in a given generation, haploid organisms often show higher fitness within a population than diploid ones.

While animals are mostly diploid, we find every variation in this life cycle in protists, so it seems quite clear that there are advantages to both conditions. And although the "advanced" plants do make up the majority of today's plant species (~250,000), there are 9,000 species of liverworts and 12,000 species of mosses, so they aren't exactly on the short road to extinction. It is true that they are all small, but that's explainable by the fact that most of them lack any sort of vascular tissue. So it's not even the case that these plants, by their stature and evolutionary success, are an illustration for the advantages of diploidy.

This is an active area of theoretical and experimental research, which means that we don't actually have any solid answers. Which makes the whole question so much more fun!

(1) Mable, B. K., & Otto, S. P. (1998). The evolution of life cycles with haploid and diploid phases. BioEssays, 20(6), 453-462.

(2) Anderson, J. B., Sirjusingh, C., & Ricker, N. (2004). Haploidy, diploidy and evolution of antifungal drug resistance in Saccharomyces cerevisiae. Genetics, 168(4), 1915-1923.

Frolicking Gulls

The Illinois Ornithological Society held it's 13th annual (where have the years gone?) Gull Frolic, as always at the Yacht Club at North Point Marina. So, in honor of that event:

Slaty-backed Gull (Larus schistisagus), North Point Marina, Lake Co, IL 2/15/2014

This Slaty-backed Gull (Larus schistisagus)is a rare visitor to most of the country, and only the first one ever seen in Lake County!

Here he is in context:

Gull spp., North Point Marina, Lake Co, IL 2/15/2014

Gulls, of course, are very social critters, and like to hang out in large groups, both when nesting and when wintering. Watching them at a favored feeding site, it's amazing how much competition there is for food -- if you see one of them with something choice, it's pretty much guaranteed to have a following of several birds trying to steal it. So why hang out together?

Well, this does mean more eyes looking out for predators, which isn't a bad thing at all. But is that enough to overcome the competition problem? In some species, the answer is clearly yes. With gulls, there's likely to be something else going on. Many social species rely on food sources that are abundant, in very local patches. So finding a patch means there's more food than you need, but your chances of finding it in the first place improve with additional sets of eyes.

Exactly what drives this has been somewhat controversial. Early suggestions that unsuccessful foragers were following more successful ones to new food sources (the Information Center Hypothesis) haven't held up too well (1) . However, it seems that those authors arguing against the idea assume (1) that successful foragers are capable of hiding that they were successful, and thus must be intentionally advertising their success, and (2) that successful foragers don't have any other reason to return to the colony or roost (an obvious oversight when dealing with nesting colonies). It may be that Ward and Zahavi made that argument in 1973 (2) , but I don't see that it's really necessary. If foraging success is essentially random, birds aren't capable of hiding their success, and there's no noticeable cost to being followed, then the advantage to social roosting should be clear.

Of course, the location of a useful food patch may not be the only sort of information being exchanged here.  The idea of local enhancement (birds simply spotting other birds foraging and joining in, without gaining any information at the roost site) seems obvious -- we can see this happening with gulls. But for this to work, birds have to be foraging within sight of each other, and for it to be most effective, they should be dispersed in a non-random way to start with. And what better way to figure out where you should look while keeping your fellows in sight than to start with them? In fact, en masse departure to foraging grounds should enhance foraging success by this argument, suggesting another means by which a social roost could be an information center.

I doubt that the gulls spend their roosting time in deep discussion about the evolutionary origins of their behavior, of course, but that behavior does provide some wonderful moments of observation for us birders. And when you find a group of birders around, you can bet that you're looking at an information center in the truest sense!

(1) Richner, H., & Heeb, P. (1995). Is the information center hypothesis a flop?. Advances in the Study of Behaviour, 24, 1-46.

 

(2) Ward, P. & Zahavi, A. (1973). The importance of certain assemblages of birds as "information centers" for food finding. Ibis 115:517-534.

Lost Spruces?

Here's a shot from Volo Bog last week:

Black Spruce (Picea mariana), Volo Bog, Lake Co, IL 2/9/2014

This is a Black Spruce (Picea mariana). There are only a handful of individuals there, at least that are visible from the boardwalk. Swink and Wilhelm state that someone clearly planted them there (1), and the Illinois Natural History Survey lists the species as introduced in the state (2). But they're found naturally in bogs as far south as Ozaukee County, WI, and they're generally slow growers in bog environments. This one is just southeast of the open center of the bog, in a spot that would have taken a lot of work to reach, through thick growths of Winterberry Holly (Ilex verticillata) and Poison Sumac (Toxicodendron vernix). It does seem rather odd that a person would go through all that to plant a few trees in the middle of a bog where they'd hardly ever be seen.

Another possibility, of course, is that they were planted nearby as ornamentals, and the seeds were then carried by the wind into the bog, where they found a favorable environment for growth. But, could these trees actually be leftovers? The idea isn't too far-fetched. James King found palynological evidence of Picea in northern Illinois as recently as 400 years ago, within a handful of lifetimes of a slow-growing tree. (3)

Volo Bog does have other species at the southern edge of their range. Pitcher Plants (Sarracenia purpurea) are the most famous, but Tamarack (Larix laricina) is also found here, limited in NE Illinois to these bogs. And then there's this guy:

Boreal Carrion Beetle (Nicrophorus vespilloides), Volo Bog, Lake Co, IL 9/26/2012

This is a Boreal Carrion Beetle (Nicrophorus vespilloides), which in North America is only found in sphagnum bogs such as Volo, and is mostly found north of Illinois. (4) Does all this mean that these Spruces didn't have human help to grow where they are? No. But it should give us pause when we assume that they did.

The question of these spruces' origin is, of course, purely academic. But it is a wonderful example of the limitations of historical data. Many sciences, including evolutionary biology, make extensive use of historical data, and we've derived some amazing insights from it. But over time information does get lost, and it's always worth remembering that we're looking at a puzzle with pieces missing, increasingly so as centuries pile into eons. Our conceptions of ancient life have changed repeatedly over the years, partly as a result of improvements in our theoretical understandings, and partly as a result of new information left over from long ago. Modern insights really are based on more information than before, which can only help improve them, but the next revolution is always waiting, under a stone or deep in a bog.

(1) Swink, F. and Wilhelm, G. Plants of the Chicago Region. (1994) Indianapolis: Indiana Academy of Science.

(2) http://www.inhs.uiuc.edu/~kenr/woody2.html

(3) King, J. E. (1981). Late Quaternary vegetational history of Illinois. Ecological Monographs, 43-62.

(4) http://bugguide.net/node/view/148730/data