Sunday, May 23, 2010

Nifty Owl Video

Nothin' geo-flavored in this post: just a completely kick-ass owl video that I recently stumbled across. The video is from some Japanese TV show, but here's a brief run-down, at least as far as I can tell from the images and different critters being shown.

The owl being shown is (probably) a Common Scops Owl (Otus scops) from South Africa. First thing you'll notice, is that it is cute as hell. However, if you stick with the video a little while, they get to the point of showing that this little guy has some awesome defense/predator avoidance strategies. Here's the video:

When the little Scops owl is confronted with a barn owl (which is just a LITTLE bigger than he is), it really puffs out in an attempt to make itself look huge. But when it's confronted with the much larger and more intimidating Eagle Owl (complete with the Imperial March as it's theme song), it instead elongates itself, producing a much slimmer, narrower profile. According to this info I found at ARKive, it seems like this is a strategy meant to make the Common Scops look more like a twig or branch!


Monday, May 17, 2010

Geomorphology From Space!!!

I recently came across a pretty neat Earth Science resource hidden away on the interwebs here, and I thought I'd share. The Goddard Earth Science Data and Information Service Center's website is, of course, a neat source for a lot of NASA flavored Earth Science info; however, they ALSO have put online a pretty big digital collection of ~270 plates from the out-of-print 1986 book "Geomorphology From Space".

It's got some neat images and interpretive maps for a variety of fairly stunning landforms, although keep in mind this was 1980s-quality pictures...of course, you could probably easily upgrade to better images via Landsat or something.

Anyway, it's pretty neat!

Sunday, May 16, 2010

Mangrove Evolution and Plate Tectonics

More Mangrove madness for May, I guess! Anyway, my previous post about some of the nifty mangroves I'd seen down in the Everglades got me thinkin': what's the evolutionary history of mangroves? Turns out, that's kind of a tricky topic, and one that ends up incorporating a lot of interesting taxonomic, ecological, botanical, and paleobotanical perspectives; as a for-instance, it requires that you make some clear definitions regarding what you mean by "mangrove". In one sense, you can talk about the taxonomic group of fruiting plants that we call "Mangroves" (which includes a lot of ~22 families). HOWEVER, in another sense, we can talk about the ECOLOGICAL niche of "mangroves", i.e., coastal swamps that develop as a result of biologically-mediated factors. A future post will explore those topics in more detail.

THIS post, however, is going to focus on some slick work (in my opinion) that has been done linking mangroves (including genetics AND fossils) with the geological factors that influenced their evolutionary history.

Workers with interests in mangroves have long recognized an interesting pattern in modern mangrove (taxonomically-defined) biogeography, namely that Mangrove species richness declines dramatically from a peak in the West Pacific to a minimum in the Caribbean/West Atlantic Zone. The figure below is from Ellison et al. (1999) that shows this pattern diagrammatically.

There are two explanations that have been put forth to explain this pattern. Originally, mangrove biogeography was explained in the context of an Indonesia/West Pacific "Center of Origin" distribution (Duke, 1995). In otherwords, mangrove taxa originated in one spot, and then subsequently disperesed globally. This is easily the oldest explanation for this observed pattern of diversity, and goes back into the literature for ~100 years.

After the plate tectonic revolution, however, another explanation presented itself: namely, that mangrove taxa evolved around the Tethys seaway in the late Cretaceous, and regional diversity is the result of diversification and evolution in the context of plate tectonics and the movement of continents (Ellison et al., 1999). This has been termed the "vicariance hypothesis", and is the big focus of the paper by Ellison et al. (1999).

Ellison et al. (1999) explore several lines of evidence as a means of testing the validity of one or the other hypotheses, and frankly, I think they're rather clever: FIRST, they take a look at the paleobiogeography of fossil mangroves (pollen or macrofossils) and compare that to modern biogeographic patterns. Ellison et al. (1999) compile a substantial list of fossil mangrove occurrence, and demonstrate that, actually, the fossil record is pretty damn good! The figure below is from Ellison et al. (1999; their figure 2), and shows generalized maps of mangrove occurrence through time.

Importantly, on the basis of their fossil mangrove occurrence database, Ellison et al. (1999) report that, statistically, there isn't any significant correlation between mangrove species-area occurrences and distance from the Indonesian/West Pacific region throughout the Tertiary. What is demonstrated, however, is that mangrove fossil occurrence shows a relativly wide-spread distribution of different mangrove taxa along the ancient Tethyan shoreline. Ellison et al. (1999) recognize that this conclusion provides testable hypotheses for relating other strongly correlated ecological aspects of mangrove environments.

This conclusion leads to their SECOND approach to interrogating mangroves....SNAILS. Turns out, mangroves have some pretty conservative associations with different gastropod taxa; in otherwords, the specific ecology and environmental stresses associated with Mangroves has also resulted in snail populations that almost always co-occur. Cooly, Ellison et al (1999) compile a fossil-occurrence database of gastropods, and compare that distribution to their fossil mangrove database! Neat, huh? Their results are shown below, in their Figure 3:

They proceed to explore ecological "nestedness" of gastropods and mangroves through time, and do some pretty nifty statistical manipulations of the data to test whether mangroves, their gastropods, and the species-area relationships can be associated with a "center-of-origin". Ellison et al. (1999) conclude that, on the basis of the fossil distributions of both mangroves, gastropods, and the patterns of their species-area relationships, that a probable Tethyan origin, and then subsequent diversification patterns are related to tectonic reconfiguration of shorelines and continents. Neat, huh!

It's a pretty neat use of both modern biogeographic patterns as well as ancient data, and it makes me wonder what other possible insights could be mined from both this and other settings? For instance, is there anything we could learn about large-scale paleo-oceanographic circulation patterns from these paleobotanical collections? Can we see other ecosystems being strongly influenced by tectonics in this way? Can we take the fossil record of mangroves, tie it to associated mangrove-dominated depositional environments, and see any statistical patterns in stratigraphic occurrence, mangrove biogeography, and tethyan tectonics? Or how expanding out from the "taxonomic" mangroves into the "ecologic" mangroves, which have a (potentially) older fossil record? Are there any statistical patterns to be elucidated from those occurrences? Who knows!?

Regardless, mangroves are obviously pretty amazing plants, but also seem to have a geological story to tell us as well! Maybe it's time us rock-o-centric types start really thinking about some of the critter-o-centric fields, and how one can inform the other in new and exciting ways.


Duke, N.C., 1995, Genetic diversity, distributional barriers and rafting continents - more thoughts on the evolution of mangroves: Hydrobiologia, v. 295, p. 167-181.

Ellison, A.M., Farnsworth, E.J., and Merkt, R.E., 1999, Origins of mangrove ecosystems and the mangrove biodiversity anomaly: Global Ecology and Biogeography, v. 8, p. 95-115.

Monday, May 3, 2010

Modern Mangroves

Just a brief picture-y related post, as I try and rise above the clinging busy-ness of the end-o'-the-semester. I was lucky enough to head down to South Florida over the spring break (in late March), and in addition to eating all sorts of delicious shell fish and exotic fruits (sapote! sapodilla!) I also had the chance to see some pretty rad mangroves swamps!

Mangroves, of course, are the utterly kick-ass salinity-tolerating plants that form impressively dense coastal swamps along tropical shorelines. Because they live in environments that are, traditionally, so hostile to plants, these awesome trees have evolved some pretty slick adaptations. They can excrete excess salt from their roots and leaves, which is pretty awesome, and can similarly limit water loss during low-tide exposures. And, from a sedimentological view point, they are also completely amazing sediment baffles, effective at dissipating incoming wave energy and trapping any entrained sediment. Neat-o!

Anyway, the picture below is from Florida bay, and just shows some isolated red mangroves growing out in the shallows. When we came back and mucked around in the mud after low tide, the WHOLE area was just covered in horseshoe crab traces going everywhere (no pictures, sadly...). In the background on the right, you can JUST make out the distopian hellscape that is Miami.

This next picture is from the Everglades, and shows some more Red Mangroves growing along the edge of the brackish water Coot Bay, and were taken as we canoed around the backwaters. Notice the oysters encrusting the mangrove limbs! Neat!

Here's another oyster and mangrove shot!

And, finally, here's some mangrove pneumatophores exposed along the canal access to Coots Bay.

Pretty amazing plants!