Radiant Little Warblers

Spotted one of these today, along with several other members of her family:

Black-and-White Warbler (Mniotilta varia),
Waukegan Beach, Lake Co, IL 5/20/2012

This is a Black-and-White Warbler (Mniotilta varia). They spend a lot of time creeping along branches looking for caterpillar lunches. Since caterpillars are hard to find in the winter around here (not to mention points north of here), they migrate south for the winter, and they're just now on their way back up.

The Wood Warbler family (Parulidae, formally speaking) is a favorite of birders across North America. (They're not found in the Old World, which explains the family's other name, the New World Warblers.) They're colorful and diverse, even traveling in mixed flocks. In some parts of the country, a good day in migration could conceivably include 30 species! Just to illustrate some of the diversity, here's a pretty pair:

Wilson's Warbler (Cardellina pusilla), Seward, AK, 8/3/2012

This one's a Wilson's Warbler (Cardellina pusilla) that I found in Alaska.

And this one's my favorite warbler, a Red-faced Warbler, (Cardellina rubifrons), photographed on the Mogollon Rim in northern Arizona.

Red-faced Warbler, (Cardellina rubifrons),
Coconino NF, Coconino Co, AZ 8/2/2005

The process that forms this sort of diverse group is known as adaptive radiation, and it's usually thought to occur when a new environment opens up, with plenty of ecological opportunities and very few competitors. Rabosky & Lovette tested this idea using wood warblers in North America, and found that rates of speciation were higher early in the radiation, slowing as time went on. (1) This fits the ecological opportunity model, as early speciation events mean that some ecological roles are now filled, and no longer open to be filled by new species.

Price, et al. looked at the timing of this radiation and compared it to Asian warblers in the family Sylviidae as well as to other North American passerines, finding that the Wood Warblers diverged much more recently than other groups, while still finding the same slowing of speciation rates over time. (2) However, they looked at specific locations rather than specific taxonomic groupings, which suggests a possibility of conflating speciation events with range shifts.

I love seeing the first warblers coming back in the spring, like little bits of flame in the trees. Being able to combine fascinating work on evolution with such beauty is a wonderful bonus.

(1) Rabosky, D. L., & Lovette, I. J. (2008). Density-dependent diversification in North American wood warblers. Proceedings of the Royal Society B: Biological Sciences, 275(1649), 2363-2371.

(2) Price, T., Gibbs, H. L., Sousa, L. D., & Richman, A. D. (1998). Different timing of the adaptive radiations of North American and Asian warblers. Proceedings of the Royal Society of London. Series B: Biological Sciences, 265(1409), 1969-1975.

A Study in Black and White

Here's a neat shot from Resurrection Bay, in southcoastal Alaska:

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

These are, of course, Orcinus orca, or Killer Whales. Here's a couple more shots:

Orca (Orcinus orca), Kenai Fjords NP, AK 8/6/2012

Orca (Orcinus orca), Kenai Fjords NP, AK 8/6/2012

These were, according to our boat captain, so-called resident Orcas, preying mostly on Salmon. There are two other ecotypes of Orca in the NE Pacific, transient and offshore. The transient whales (well, big dolphins in fact) feed primarily on marine mammals, dolphin, porpoises, and especially seals. The offshore ones feed largely on sharks and other offshore fish. (1) This dietary specialization has impacts on precisely where you're likely to find each type, as well as on the sizes of their pods and subsequently on their social structures. (2) It's quite likely, according to the IUCN, that the species will be split in some fashion in the near future, so for the moment they haven't evaluated them. (3)

As if 3 overlapping species in one part of the ocean weren't enough, we find the same scenario in Antarctic waters, where three visually distinctive types feed on, respectively, Southern Minke Whales, seals, and toothfish. (4) A fourth type, just recently described, appears to feed on toothfish as well. (5)

I haven't found any discussion of distinct ecotypes in the Atlantic, but Orca are generally harder to find in Atlantic waters, so they're not nearly as well known there. Where they are commonly found, though, the resident forms at least are relatively easy to study (for whales, anyways) -- they're big, quite visible, and use fairly small home ranges where they can be seen quite frequently. Despite that, we're still not even sure how many species we have of these fascinating animals.

(1) Baird, R.W. 2000. The killer whale: Foraging specializations and group hunting. pp. 127-53. In: J. Mann, R.C. Connor, P.L. Tyack and H. Whitehead (eds.) Cetacean Societies. University of Chicago Press, Chicago. 433pp.

(2) Heimlich-Boran, J. R. (1988). Behavioral ecology of killer whales (Orcinus orca) in the Pacific Northwest. Canadian Journal of zoology, 66(3), 565-578.

(3) Taylor, B. L., Baird, R., Barlow, J., Dawson, S. M., Ford, J., Mead, J. G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R. L. (2008). 'Orcinus orca'. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 2009-01-01.

(4) Pitman, R. L., & Ensor, P. (2003). Three forms of killer whales (Orcinus orca) in Antarctic waters. Journal of Cetacean Research and Management, 5(2), 131-140.

(5) Pitman, Robert L.; Durban, John W.; Greenfelder, Michael; Guinet, Christophe; Jorgensen, Morton; Olson, Paula A.; Plana, Jordi; Tixier, Paul; Towers, Jared R. (2010). "Observations of a distinctive morphotype of killer whale (Orcinus orca), type D, from subantarctic waters". Polar Biology 34 (2): 303–306.

A Trio of Trillium

In honor of spring, here's some of the first wildflowers of the spring, on their way up to the light:

Prairie Trillium (Trillium recurvatum),
Van Patten Woods FP, Lake Co, IL 4/20/2014

These are Prairie Trillium (Trillium recurvatum), a rather odd name given that in Illinois they're found in open oak woodlands, rather than open prairies. These had just emerged, but by now they probably look more like this:

Prairie Trillium (Trillium recurvatum),
Van Patten Woods FP, Lake Co, IL 5/19/2003

If you think that one's pretty, take a look at this one from Pennsylvania:

Painted Trillium (Trillium undulatum),
Allegheny NF, Westmoreland Co, PA 5/19/2005

This is Painted Trillium (T. undulatum), a native of rich Appalachian hardwood forests.

And this one, from Ryerson Forest Preserve here in Lake County:

White Trillium (Trillium grandiflorum), Ryerson FP, Lake Co, IL 5/29/2003

This is White Trillium (T. grandiflorum).

White Trillium, being an exceptionally showy and abundant flower (in places, our forest preserves look carpeted in white from these guys), is noticed in it's absence. Here in Lake County, high deer populations have at times impacted Trillium populations. They tend not to disappear right away, but get progressively shorter over several years, until they're no longer able to flower. (1) Our forest preserves now practice population control methods to keep deer numbers down, and Trillium is doing just fine.

Another study shows that, while deer in large numbers are problematic, deer in smaller numbers can be helpful for White Trillium (and presumably for other trilliums as well). While most trillium seeds are dispersed by ants, deer are quite capable of doing so as well, and when they do disperse the seeds, they tend to do so at much greater distances than the ants manage. (2) This means that deer are an important determinant of the genetic population structure of the trillium -- not exactly the way I think of plant-herbivore interactions!

(1) Anderson, R. C. (1994). Height of white-flowered trillium (Trillium grandiflorum) as an index of deer browsing intensity. Ecological Applications, 4(1), 104-109.

(2) Vellend, M., Myers, J. A., Gardescu, S., & Marks, P. L. (2003). Dispersal of Trillium seeds by deer: implications for long-distance migration of forest herbs.Ecology, 84(4), 1067-1072.

Bright Colors For a Drab Day

Windy and cooler today, so here's a couple of zoo shots:

Golden-breasted Starling (Lamprotornis regius)
Lincoln Park Zoo, Cook Co, IL  9/30/2012

This is a Golden-breasted Starling (Lamprotornis regius) from the Lincoln Park Zoo.

Emerald Starling (Lamprotornis iris)
Lincoln Park Zoo, Cook Co, IL  9/30/2012

This one's an Emerald Starling (L. iris), again from Lincoln Park. The brilliant greens and purples we see here are the result of iridescence, not pigment. The barbs on the feathers are structured such that certain wavelengths are reflected back while others are transmitted farther into the feather, where they are absorbed by a layer of melanin. In some species, this works at any angles (think Blue Jays), but in iridescent species like this, the apparent color varies with the angle that the feather makes with the light.

This structural coloration is responsible for all of the blue colors that we see in birds. Green colors in most birds come from either iridescence, as here, or as a structural blue mixed with a yellow carotenoid pigment.

But here's a green bird that doesn't depend upon structural color at all:

 Livingston's Turaco (Tauraco livingstonii),
Milwaukee County Zoo, WI 6/5/2006

This is a Livingston's Turaco (Tauraco livingstonii), taken at the Milwaukee County Zoo. The green you see here is actually due to pigment, specifically to turacoverdin, a group of porphyrin pigments once thought to be unique to turacos.

Here's another turaco:

 Violaceous Turaco (Musophaga violacea),
Milwaukee County Zoo, WI 6/5/2006

This is a Violaceous Turaco (Musophaga violacea), again from the Milwaukee County Zoo. (Both of these turacos, and indeed all turacos, are native to Africa.) I can't find any source discussing the blue color you see here, so I assume it's due to structure. This color, though, isn't:

 Violaceous Turaco (Musophaga violacea),
Milwaukee County Zoo, WI 6/5/2006

The red you see on this guy's wing is due to turacin, another porphyrin unique to this group.

Pigments very similar to turacoverdins have recently been found in Galliformes, leading some researchers to suggest that turacos evolved from Galliformes. (1) On the other hand, another very similar pigment has been found in jacanas, members of the Charadriiformes, which suggests to me that evolving these pigments may be easy enough to make their presence a bit chancy as an indicator of phylogeny.

(1) Dyck, Jan (January 1992). "Reflectance spectra of plumage areas colored by green feather pigments". The Auk. 109(2): 293–301.

A Novel In Stone.

100 posts! So, here's a shot from a trip I took last summer:

Dinosaur National Monument, Moffat Co, CO 5/25/2013

This is part of Dinosaur National Monument, on the border of northwest Colorado and northeast Utah. It's a neat spot, since the lack of water means we can see a lot of the underlying rock. And those rocks tell a long, slow story, if we're able to read it.

How would we do that? The same way we would read the story we see here:

Black Oak (Quercus velutinus),
 Illinois Beach State Park, Lake County, IL 4/25/2014

This Black Oak probably fell over in our big storm a few years ago, and the park cut it off to keep it from falling the rest of the way onto the trail. If you look closely, you can see that the rings formed around two centers, which tells us that this tree probably had it's tip cut off (by a deer, or maybe a rabbit?) when it was just a sapling, so it grew two trunks. If we were to count the rings, of course, we could tell how old the tree was when it died. If you look at the upper left, there's a darker area, which suggests that the tree survived a fire a while back, and we can see where and when several branches began growing on the lower left. Since the tree died, you can see that there have been fungi and insects working around the outsides, with some tunnels probably caused by beetle larvae in the upper right.

Much of this story probably predates my moving into the area -- oaks are slow growers. Despite that, I feel quite confident that we can know what happened to this tree. We can watch these processes happen elsewhere, and observe the signs that those processes leave behind. That gives us the knowledge we need to infer those processes when all we have are the signs that remain.

This is how we would read the story of Dinosaur National Monument, too. We can observe sediments settling in various settings, we can compress and heat small samples of those same sediments to see how rock forms, and we can compare the fossil remains that Dinosaur is famous for to modern creatures and to fossils from other locations on Earth. Those modern processes tell us, for instance, that the most famous fossils in the park came from animals that were buried in a river's floodplain, in an otherwise rather dry area. And they tell us that sediments form in horizontal layers -- when we see angled layers of rock, or curls like we see here, then we can confidently say that the land itself has been folded by the immense forces of continental drift.

I sometimes tell my students that every place has a story to tell, if we take the time to learn the language. Sometimes the story is short, in a script best read by ecologists. Sometimes, as here, it's a Russian novel, set in a font defined by millions of years of geology.

Rhinos and Friends

Here's some cool zoo critters:

 Black Rhino (Diceros bicornis), Lincoln Park Zoo, Cook Co, IL 1/26/2012

This is a Black Rhino (Diceros bicornis), from the Lincoln Park Zoo.

Sumatran Rhino (Dicerorhinus sumatrensis),
Cincinnati Zoo, Hamilton Co, OH, 3/29/2012

This one's a Sumatran Rhino (Dicerorhinus sumatrensis) from the Cincinnati Zoo, one of just a handful of zoos worldwide to breed them. Interestingly enough, despite its tropical home, it's closest relative is considered to be the extinct Ice Age Woolly Rhinoceros.

Grevy's Zebra (Equus grevyi), Henry Doorley Zoo, Omaha, NE 12/30/2011

This is a Grevy's Zebra (Equus grevyi) from the Omaha Zoo.

Malayan Tapir (Tapirus indicus),
Henry Doorley Zoo, Omaha, NE 12/30/2011

And this comical looking critter is a Malayan Tapir (Tapirus indicus), also from the Omaha Zoo.

All of these animals share two things -- a taxonomic group (the order Perissodactyla) and a listing of at least Endangered by the IUCN. (1)

They aren't alone in either of those -- of 17 living species of Perissodactyla, or odd-toed hoofed mammals, 3 haven't been evaluated (Domestic horses (E. ferrus caballus) and donkeys (E. asinus), and Burchell's Zebra (E. burchelli (?)) -- the last probably due to some taxonomic confusion over whether it's a legitimate species, or even if it's still extant). One, the Tibetan Kiang (E. kiang), a wild donkey, is listed as Least Concern. Another one, the White Rhinoceros (Ceratotherium simum), is listed as Near Threatened. The other 11 break down like so: 3 vulnerable, 5 endangered, and 3 critically endangered. One more, Tapirus kabomani, was only formally described last year, so it hasn't been evaluated yet. (2)

Even before humans arrived on the scene, quite a few Perrisodactyls went extinct -- there are 11 fossil families, none of which survived long enough to have seen modern Homo sapiens. (3) But the ones that are left are survivors -- as long as they don't have to deal with burgeoning human populations. Today, it's all too easy to imagine a world where one of the most important early groups of modern mammals is barely a memory, racing down the track of extinction.


(1) www.onezoom.org

(2) IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 25 April 2014.

(3) http://www.tolweb.org/Perissodactyla/15980

Little Yellow Ranchers

I found this little guy in Gander Mt. last week:

This is a Little Yellow Ant, (Lasius claviger). They are primarily subterranean, which explains the small eyes. I found this guy by rolling a log over.

Little Yellow Ant (Lasius claviger), Gander Mt. FP, Lake Co, IL 4/19/2014

Then I rolled another log, and got this shot:

Little Yellow Ant (Lasius claviger) with aphids,
 Gander Mt. FP, Lake Co, IL 4/19/2014

When I took it, I figured that the white little critters were ant larvae. When I looked at the shots later, I realized they were considerably more interesting -- they're root-eating Aphids (family Aphididae)! Why is this so interesting? Because the ants aren't eating the aphids -- they're milking them! If you look closely, you might see that there's a drop of liquid being excreted by many of the aphids. Because of their diet, this liquid is high in sugar, which makes it an excellent food for the ants. So they actually tend the aphids, guard them, and yes, even milk them!

This particular species of ant is impressive for another reason. They're social parasites. (1) In most species of ants, the females undergo their mating flight, then establish new colonies of workers that gather food for the winter. This species (and several others in the genus) fly later, so late in fact that they wouldn't be able to establish a new colony of their own. Instead, the females enter the nest of one of their congeners, kill the queen, and take over the colony. (In this particular species, females may hibernate on the surface, then enter the host colonies early in the spring.)

These behaviors (ranching and coups d'etat) are the stuff of human history -- we like to think that we used our vaunted intelligence to invent them, and that's true. But these little ants don't have any intelligence to speak of, and they managed to invent these behaviors (and others -- agriculture, slavery, etc.) despite the lack. If you have enough critters with enough variation, you can explore a very large set of potential solutions to the problems of life. It's wasteful -- most variations fail. But if you don't care about how many little ants die on the way, this method will come up with all sorts of answers.

One of the characteristics of human methods of problem solving is that we seek to understand the problem, to simplify it so that we can tell ourselves a coherent story about it. Evolution doesn't need to do this, so often the answers it comes up with are stranger and more complicated than anything we create, sometimes to the point that we can't understand them at all. And yet, they work! Typically when we can manage to work out what's going on, we find all sorts of built-in inefficiencies, leftovers from the history of the organism. But computer programmers that specialize in so-called evolutionary algorithms have demonstrated that under the right circumstances, this sort of extreme trial and error can result in solutions that outdo anything we've ever come up with ourselves.

(1) Raczkowski, J. M., & Luque, G. M. (2011). Colony founding and social parasitism in Lasius (Acanthomyops). Insectes sociaux, 58(2), 237-244.

A Humble Fish

A nice little shot from Illinois Beach State Park yesterday:

 Longnose Suckers (Catostomus catostomus), Illinois Beach SP,
Lake Co, IL  4/21/2014

These are Longnose Suckers (Catostomus catostomus), a common species in the Great Lakes. Lake-dwelling suckers often ascend smaller streams to spawn, just as salmon do along the coasts, and that's likely what was happening here, since they were about 30 feet from the lake on a small creek, and since I generally don't see them here.

As common, widespread, fairly large fish that feed on the bottom, Longnose Suckers and their congeners, White Suckers (C. commersoni) have been commonly examined for effects of chemical pollutants, including cadmium (1), copper and zinc (2), and  wood pulp effluent (3,4). Munkittrick & Dixon have even suggested sampling sucker populations as an assay for chemical pollution. (5)

Suckers aren't sexy fish; while they are sometimes eaten, they aren't highly sought-after game species, and they're not endangered. Just a humble critter in a humble role, which just happens to make them particularly useful species.

(1) Duncan, D. A., & Klaverkamp, J. F. (1983). Tolerance and resistance to cadmium in white suckers (Catostomus commersoni) previously exposed to cadmium, mercury, zinc, or selenium. Canadian Journal of Fisheries and Aquatic Sciences, 40(2), 128-138.

(2) Growth, fecundity, and energy stores of white sucker (Catostomus commersoni) from lakes containing elevated levels of copper and zinc. Canadian Journal of Fisheries and Aquatic Sciences, 45(8), 1355-1365.

(3) Gagnon, M. M., Dodson, J. J., Hodson, P. V., Kraak, G. V. D., & Carey, J. H. (1994). Seasonal effects of bleached kraft mill effluent on reproductive parameters of white sucker (Catostomus commersoni) populations of the St. Maurice River, Quebec, Canada. Canadian Journal of Fisheries and Aquatic Sciences, 51(2), 337-347.

(4) Kloepper‐Sams, P. J., Swanson, S. M., Marchant, T., Schryer, R., & Owens, J. W. (1994). Exposure of fish to biologically treated bleached‐kraft effluent. 1. Biochemical, physiological and pathological assessment of rocky mountain whitefish (prosopium williamsoni) and longnose sucker (catostomus catostomus). Environmental toxicology and chemistry, 13(9), 1469-1482.Munkittrick, K. R., & Dixon, D. G. (1988). 

(5) Munkittrick, K. R., & Dixon, D. G. (1989). Use of white sucker (Catostomus commersoni) populations to assess the health of aquatic ecosystems exposed to low-level contaminant stress. Canadian Journal of Fisheries and Aquatic Sciences, 46(8), 1455-1462.

A Flat Little Ruby

Here's a little gem from Sedge Meadows FP yesterday:

Red Flat Bark Beetle (Cucujus clavipes), Sedge Meadow FP,
Lake Co, IL 4/20/2014

This is a Red Flat Bark Beetle (Cucujus clavipes). They normally hang out under tree bark -- I don't know why he flew out to a roadside barrier.

If you're wondering why he's called a Flat Bark Beetle -- here's why:

Red Flat Bark Beetle (Cucujus clavipes), Sedge Meadow FP,
Lake Co, IL 4/20/2014

This species is widely distributed across North America, although it appears to avoid the deep South. This distribution includes Alaska, where winter temperatures can get extremely cold; this can be a serious problem if you're an insect. How cold-blooded insects survive winters that get well below freezing is a matter of considerable interest, and this species has been helpful in that regards.

As many species do, they overwinter as larvae. In Alaska, they're known to survive down to -100 degrees C! (1) Beetles in Indiana don't have to survive such low temperatures, and the two populations show some interesting differences in physiology as a result. (2) Both populations supercool, with Indiana individuals freezing around -23 degrees C, and Alaska individuals at -35 to -40 degrees C, or even colder. Both populations produce glycol molecules, which act as antifreeze compounds, in similar amounts. But Alaskan beetles actually dehydrate themselves, which raises the glycol concentrations and lowers the freezing point. They can also vitrify (their body fluids freeze in a glassy state rather than a crystalline one, which means less cellular damage), and they are the first species of insects known to do so.

We had a historically cold, snowy winter, but these guys took it in stride, and I end up with a little ruby for my collection.

(1) Sformo, T., Walters, K., Jeannet, K., Wowk, B., Fahy, G. M., Barnes, B. M., & Duman, J. G. (2010). Deep supercooling, vitrification and limited survival to-100 {degrees} C in the Alaskan beetle Cucujus clavipes puniceus (Coleoptera: Cucujidae) larvae. The Journal of experimental biology, 213(3), 502.

(2) Bennett, V. A., Sformo, T., Walters, K., Toien, O., Jeannet, K., Hochstrasser, R., ... & Duman, J. G. (2005). Comparative overwintering physiology of Alaska and Indiana populations of the beetle Cucujus clavipes (Fabricius): roles of antifreeze proteins, polyols, dehydration and diapause. Journal of Experimental Biology, 208(23), 4467-4477.

A Shrimp's Tiny Little Cousin

Here's a neat little critter from this morning's jaunt at Gander Mt.:

Woodlouse (Oniscidea), Gander Mt. FP, Lake Co, IL  4/19/2014

This is a Woodlouse, in the order Isopoda, suborder Oniscidea. They're crustaceans, which means that despite being entirely terrestrial, they breathe through gills. This means that they're limited to moist environments - typically forest soil and decomposing wood. (This one was underneath a fallen log.) They are abundant, and several species are affectionately known by kids as Roly-Polies, for their ability to roll into a ball when disturbed.

They are entirely harmless decomposers, feeding on fallen plant material. Escher, et al. took advantage of their abundance to test differences in the differences in decomposition between Bt transgenic corn and non-transgenic corn. They did find differences in the breakdown rate of several compounds, but the results were a mixed bag: lignin broke down more rapidly in the transgenic plants, simpler carbohydrates in non-transgenic plants. The woodlice showed no differences in feeding rates between the two strains, and reproductive rates were similar, but they gained weight faster and had higher juvenile survival rates when fed transgenic corn. (1)

 Paoletti & Hassall examined how well woodlice could be used to examine nutrient and pollutant levels in agricultural settings. They found that their abundance, ease of both capture and identification, and sensitivity to pesticides and other pollutants make them excellent candidates. (2)

Such a humble little critter to serve such a lofty purpose!



(1) Escher, N., Käch, B., & Nentwig, W. (2000). Decomposition of transgenic< i> Bacillus thuringiensis</i> maize by microorganisms and woodlice< i> Porcellio scaber</i>(Crustacea: Isopoda). Basic and Applied Ecology, 1(2), 161-169.

(2) Paoletti, M. G., & Hassall, M. (1999). Woodlice (Isopoda: Oniscidea): their potential for assessing sustainability and use as bioindicators. Agriculture, ecosystems & environment, 74(1), 157-165.

Swallows Do Make The Spring

It's finally feeling like spring, there are at least a few flying insects around, and right on cue, these guys are arriving:

Tree Swallow (Tachycineta bicolor), Gander Mt. FP,
Lake Co, IL  5/23/2012

This is a Tree Swallow (Tachycineta bicolor). And here's a few of his relatives:

Violet-Green Swallow (Tachycineta thalassina), Garden of the Gods Park,
El Paso Co, CO 5/25/2013

This handsome gentleman is a Violet-Green Swallow (T. thalassina). They're found out west, but there are a handful of records from Illinois, including one last year from Lake County.

Northern Rough-winged Swallow (Stelgidopteryx serripennis),
Gander Mt. FP, Lake Co, IL  6/30/2012

This is a family of juvenile Northern Rough-winged Swallows (Stelgidopteryx serripennis). (Sometimes I think that scientific names have an inverse relationship to the size of the organism!) You can tell they're juveniles by the very fresh plumage and the yellow corners to the mouth. And finally, just because:

Barn Swallow (Hirundo rustica), Horicon NWR, Dodge Co, WI 8/13/2013

This is a Barn Swallow (Hirundo rustica), midflight. If you're British, you'd know this one as simply Swallow, but that doesn't work so well here in the States.

Swallows have been the subject of numerous studies -- they're fairly diverse, but not overwhelmingly so, they tend to be quite approachable, including at nesting sites, many will use artificial nest boxes or buildings, and many of them nest colonially, all useful traits from a biologist's viewpoint. A particularly interesting article from 1993 examined the evolution of nest building behavior in swallows, mapping it onto a molecularly-derived phylogeny. (1)

They found that ancestral swallows probably nested in burrows, as do modern Bank (Riparia riparia) and Rough-winged Swallows. This lineage produced two offshoots, one that utilizes already-existing cavities (often old woodpecker holes) and one that builds mud nests, in some cases hanging them from the undersides of eaves, cave mouths, etc. The authors argued that the cavity nesters are a monophyletic group that evolved in the New World (in the US it includes Purple Martins (Progne subis), Tree Swallow and Violet-Green Swallow), and that their diversification was tied to recent mountain building and the resulting diversity of forest types. Clay-nesters apparently diversified in Africa, and must have colonized the New World more recently, since Barn, Cliff (Petrochelidon pyrrhonota), and Cave Swallows (P. fulva) all build mud nests.

I find it interesting that nest-building techniques are fairly conservative -- with approximately 85 species, they only found 3 main types of nest, and each one seemed to have evolved only once. Other types of traits can evolve so quickly that this sort of analysis yields little insight, while still other traits change so seldom that there wouldn't be any variation to examine in a group so small. Before seeing this paper, I would have guessed that nest-building techniques would fall into the too quick category.

(1) Winkler, D. W., & Sheldon, F. H. (1993). Evolution of nest construction in swallows (Hirundinidae): a molecular phylogenetic perspective. Proceedings of the National Academy of Sciences, 90(12), 5705-5707.

A Tiny Little Scavenger

Just a quick note tonight, about this little guy:

Black Scavenger Fly, family Sepsidae, Lyons Woods FP, Lake Co, IL 4/17/2014

This is a male Black Scavenger Fly, in the family Sepsidae. According to Arnett, there are 34 species north of Mexico, (1) and many of them look similar, so I'll probably never know which one.

These guys have some rather unsavory habits, by our standards: their larvae feed in animal droppings. The adults tend to hang out nearby, and mating takes place almost exclusively near dung. This happens soon after the material is deposited, (2) and often involves some very species-specific structures on both male and female. (This sort of thing isn't unusual in many insects.) Such specialization most likely happens through various forms of sexual selection, and since these guys are easy to attract, they've been used to test a number of hypotheses about the forms that sexual selection can take. (3,4)

Yesterday I didn't even know this family existed, and today, I find out that its a commonly researched group of critters! It's no wonder biologists specialize -- a whole planet full of critters is simply too much for any one person to truly comprehend.

(1) Arnett, R. (2000). American insects: a handbook of the insects of America north of Mexico. CRC Press, Boca Raton.

(2) Parker, G. A. (1972). Reproductive behaviour of Sepsis cynipsea (L.)(Diptera: Sepsidae). I. A preliminary analysis of the reproductive strategy and its associated behaviour patterns. Behaviour, 172-206.

(3) Puniamoorthy, N., Ismail, M. R. B., Tan, D. S. H., & Meier, R. (2009). From kissing to belly stridulation: comparative analysis reveals surprising diversity, rapid evolution, and much homoplasy in the mating behaviour of 27 species of sepsid flies (Diptera: Sepsidae). Journal of evolutionary biology, 22(11), 2146-2156.

(4) Eberhard, W. G. (2005). Sexual morphology of male Sepsis cynipsea (Diptera: Sepsidae): lack of support for lock-and-key and sexually antagonistic morphological coevolution hypotheses. The Canadian Entomologist, 137(05), 551-565.

A Tale of Three Caterpillars (?)

Here's a fun shot from a few days ago:

Dotted Gray (Glena cribritaria),
Van Patten Woods FP, Lake Co, IL  3/30/2014

This little twig was, apparently, growing off of a wooden signpost in a local Forest Preserve. (I've photographed some neat little critters on those posts.)

Of course, closer examination proved it to be a caterpillar -- specifically (I think) a Dotted Gray (Glena cribrataria), one of the Geometridae. You can tell it's a Geometrid because it's only got three pairs of abdominal prolegs. (Those leg-like structures at the back end, including the pair holding onto the post.)

This sort of camouflage is quite common in caterpillars. After all, if you're slow, taste good (I assume they do, since warblers love them, but I think I'll forgo testing that), and don't have teeth, you're better off hiding.

So what about this guy?

Unexpected Cycnia (Cycnia inopinatus), Illinois Beach State Park,
Lake Co, IL 9/22/2011

This is an Unexpected Cycnia (Cycnia inopinatus). That bright color really stands out -- there were a lot of them around that season, and they were easy to see in the green vegetation. Clearly, they're not trying to hide.

The spines on the back might be part of the answer here. Some caterpillars have irritating hairs, and some can flat-out sting. (Saddleback Caterpillars are notorious for it!) But while it's hard to tell from the photo, the plant he's eating has more to do with that bright color. That's a Swamp Milkweed (Asclepias incarnata). Like all Milkweeds, it produces some rather nasty defensive compounds, which any insect that eats it is going to have to deal with. Most prefer to avoid eating milkweeds entirely, but those that will eat them often sequester those chemicals, making themselves distasteful to their potential predators. Of course, being distasteful isn't much help if the predator has to eat you to find out, so many of these species have developed bright colors as a warning to predators.

Frequently, when we find species that have those warning colors, we also find species that mimic them, gaining the protection without having to incur the costs. But sometimes species resemble each other for entirely different reasons. Like this guy:

Phymatocera sp., Van Patten Woods FP, Lake Co, IL 8/23/2013

This isn't a caterpillar at all -- it's a sawfly, in the genus Phymatocera. Sawflies are in the same order as bees and wasps, and many of the adults resemble wasps, but they can't sting. The larvae, as seen here, resemble caterpillars and mostly eat plant materials. (The easiest way to tell them apart is to count the prolegs. Caterpillars will have 5 pairs or fewer (as few as 2 in geometrids), sawflies have 6 or more.) But they aren't mimicking caterpillars -- this general body plan appears to be an ancestral larval state for a large group of insects, with beetle grubs, wasp larvae, and caddisfly larvae all looking like this as well.

Camouflage and mimicry have produced some amazing lies in the animal kingdom, but it's worth remembering that sometimes the mimicry itself is an illusion.

A (Sort Of) Pig of Another Stripe

My students were dissecting pigs this evening, so I offer up these guys to your more tender mercies:

Collared Peccary (Pecari tajacu), Omaha Zoo, Omaha, NE 12/30/2011

This is a Collared Peccary, (Pecari tajacu). They occur from the southwestern US south through much of South America, but this one lives in the Omaha Zoo. While they may look like pigs, peccaries actually make up the family Tayassuidae, which is native to the New World. (True pigs are Old-World species in the family Suidae.)

Chacoan Peccary, (Catagonus wagneri), Sunset Zoo, Manhattan, KS 5/22/2013

This one's a Peccary, but it's not a Collared Peccary. It's a Chacoan Peccary (Catagonus wagneri). Here's a closer look (apparently they love grapevines):

Chacoan Peccary, (Catagonus wagneri), Sunset Zoo, Manhattan, KS 5/22/2013

This species is confined to thorn forests in a small area of Paraguay, Bolivia, and Argentina. There are roughly 3000 in the world, and the IUCN lists them as endangered. (1) The one shown above lives at the Sunset Zoo in Manhattan, Kansas, one of several zoos attempting to breed the species. However, since the largest threats to the species include large-scale habitat alteration for farming and hunting by an ever-increasing human population in the region, (2) it seems unlikely that reintroduction programs will be starting anytime soon.

If we do lose the species, it won't be for the first time: Chacoan Peccaries are a member of a very select club -- they were first described as a fossil species, in 1930. It wasn't until 1975 that the local knowledge of their existence was published. (3) There is still a good deal of discussion about the role of humans in the disappearances of the world's Pleistocene faunas. If we lose the Chacoan Peccary a second time, there won't be any need for debate -- we'll know we were responsible.

(1) IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 15 April 2014.

(2) Altrichter, M., & Boaglio, G. I. (2004). Distribution and relative abundance of peccaries in the Argentine Chaco: associations with human factors. Biological Conservation, 116(2), 217-225.

(3) Wetzel, R. M. (1977). THE EXTINCTION OF PECCARIES AND A NEW CASE OF SURVIVAL*. Annals of the New York Academy of Sciences, 288(1), 538-544.

Slow but Steady

Found this guy on the trail at Illinois Beach today:

Meadow Slug (Deroceras laeve), Illinois Beach State Park, Lake Co, IL  4/13/2014

This is Deroceras laeve, the Meadow Slug. (At least according to the INHS -- there doesn't appear to be a standardized source for molluscan common names.) It's apparently naturally Holarctic in distribution, as all of the sources I checked stated that it was native here.

Slugs are, of course, snails that have evolved right out of their shells. Snails are pretty diverse ecologically, with some eating mostly plants and others mostly animals, often other molluscs. (Let's face it, catching active prey is not likely to be a snail's strong point!) It shouldn't be surprising, then, that slugs sometimes prey on animals as well, and this species has been observed feeding on a wide range of items, including beetle grubs and sawfly eggs and larvae. (1) This sort of generalized behavior probably helps explain their wide distribution.

Another factor in that distribution appears to be their tolerance to the cold temperatures expected in the northern half of our hemisphere, as D. laeve turns out to be notably more freeze-resistant than the introduced D. reticulatum and Arion circumscriptus. (2)

When we think of slugs at all, it's usually in the context of their damage to our vegetable gardens, but a native, freeze-tolerant species with abundant enemies of its own, that's able and willing to attack insect pests, seems like an ideal biological control agent - Sweetman suggested this back in 1958! (3) But we do need to be careful with this idea, as we can see from the tale of Achatina fulica, a very large snail from Africa sometimes introduced as a food source. When it was released onto the Marquesas Islands, it outcompeted a number of endemic tree snails, to the point of extinction, and there are concerns that it will do the same in Hawaii. (4)

(1) FOX, L., & Landis, B. J. (1973). Notes on the predaceous habits of the gray field slug, Deroceras laeve. Environmental entomology, 2(2), 306-307.

(2) Storey, K. B., Storey, J. M., & Churchill, T. A. (2007). Freezing and anoxia tolerance of slugs: a metabolic perspective. Journal of Comparative Physiology B, 177(8), 833-840.

(3) Sweetman, H. L. (1958). The Principles of Biological Control. Interrelation of Hosts and Pests and Utilization in Regulation of Animal and Plant Populations.The Principles of Biological Control. Interrelation of Hosts and Pests and Utilization in Regulation of Animal and Plant Populations., (Revd. edn. 11 1/4× 8 1/2).

(4) Elton, C. C. (1958). The reasons for conservation (pp. 143-153). Springer Netherlands.

Life Among the Ants

Here's a neat little guy that I had never heard of before yesterday:

Eastern Ant Cricket (Myrmecophilus pergandei),
Gander Mt. FP, Lake Co, IL  4/11/2014

This is an Eastern Ant Cricket (Myrmecophilus pergandei). I found this one living in a nest of small ants, possibly Lasius alienus. Apparently they normally live in ant nests, eating food gathered by the ants. I've seen this lifestyle, often termed inquiline, described as both kleptoparasitism and commensalism.

This particular species is a generalist, living with a number of different ant species, while others in the genus are more specialized. (None of the specialized species occur in the US except for M. americanus, which despite the name is an Old World species that occurs with the introduced Longhorn Crazy Ant (Paratrechina longicornis) (1,2)). Specialists often interact directly with their host species. (3) Since ant interactions are chemically mediated, it's apparent that these crickets mimic their host's chemical signals.

Among the ants, those signals are species-specific, which means that a specialist will have considerable trouble mimicking more than one species. Generalists avoid this problem mostly by avoiding the ants -- a technique that likely reduces their foraging success and probably leads to them being killed or ejected from the nest occasionally. On the other hand, generalists are frequently able to live without the ants - specialists typically aren't. (3) (How they reach new nests in the first place is, I'm sure, a fascinating topic.)

These two end points are easy to understand. The pathways from generalist to specialist are often difficult to untangle, but in this case we have what looks like an example of the early stages: a species (M. tetramorii from Japan) that is a host specialist but doesn't rely on chemical signals, and in fact does routinely suffer attacks from the host ants. (4)

(1) Wetterer, J. K., & Hugel, S. (2014). First North American Records of the Old World Ant Cricket Myrmecophilus americanus (Orthoptera, Myrmecophilidae).Florida Entomologist, 97(1), 126-129.

(2) Hebard, M. (1920). A Revision of the North American Species of the Genus Myrmecophila (Orthoptera; Gryllidae; Myrmecophilinae). Transactions of the American Entomological Society, 91-111.

(3) Komatsu, T., Maruyama, M., & Itino, T. (2009). Behavioral differences between two ant cricket species in Nansei Islands: host-specialist versus host-generalist. Insectes sociaux, 56(4), 389-396.

(4) Itino, T. (2013). Nonintegrated Host Association of Myrmecophilus tetramorii, a Specialist Myrmecophilous Ant Cricket (Orthoptera: Myrmecophilidae). Psyche: A Journal of Entomology, 2013.