IM Interview: Secret Lives of Animals -- Past and Present

The scoop: Bones, ligaments, shells, hair, feathers and other animal debris have always been interesting. But now they've become treasure troves of information, thanks to new techniques that allow specific versions of certain elements, called isotopes, to be counted and read like books. These books describe the lifestyles and ranges of animals, even the climate they lived in. Kena Fox-Dobbs is at the forefront of this new field which is shedding light on everything from how condors survived the end of the ice age, to where your neighborhood owls, falcons and bats hang out in the off season.

kenafd: Hi Larry

larryo': You there?? Oh yeah. There you are. Where are you these days. Seems you have been moving a bit?

kenafd: I just finished a year long postdoc in the Zoo and Phys dept at Univ of Wyoming, and am now at the University of Puget Sound in Tacoma as an asst prof in the Geo dept. Yes, lot's of moving!

larryo': Quite a multi-disciplinary resume you have!

kenafd: Hard to decide where to call home! Geo, Bio...

larryo': You are sort of the poster child for how a science can go that way.

kenafd: Well, I think a lot of paleo [paleontology] folks walk this line, and then you add the fact that I use a geochemical tools to address ecological questions, and it just gets messy, in a strict disciplinary sense!

larryo': Messy and productive! I first encountered you when you published the work on condors, I recall. Very surprising stuff. Was that a turning point for you?

kenafd: Yes, that project really did open my eyes to the modern conservation implications of paleoecological work. Definitely motivated me to expand my temporal scope.

larryo': I'll link here to the news story I did on that condor work, so we don't have to go into that too much. Could you break down what this general approach is, however, so readers get an idea?

kenafd: Sure. Essentially, I was trying to identify an ecological mechanism to explain the geographic pattern of condor survival after the late Pleistocene megafaunal [i.e. saber-tooths, camels, mammoths, etc.] extinction ~10,000 years ago in N. America. Using stable isotope analyses of fossil bone collagen I was able to show that Pleistocene condors along the CA coast had a diet that included marine and terrestrial carrion, whereas condors from other eastern and inland sites relied solely upon terrestrial resources, that then disappeared (eg. mammoth, horse, etc). Marine resource use - specifically scavenging upon marine mammal carrion - was a dietary 'buffer' that allow coastal condors to survive.

larryo': So this changes the way we look at the history of the condors in California. Right?

kenafd: You bet. They really are 'survivors'. Interesting context for their current wild existence in small, reintroduced populations. Although, reintroduced condors have been observed feeding on seal and whale carcasses along the CA coast in the past few years - returning to their ancient foraging strategy. Very exciting.

larryo': Wow. That is cool! Hadn't heard about that. Have there been lot of other studies that followed similar patterns? I mean, is this sort of growing field?

kenafd: In a general sense, yes - there have been some exciting other recent isotopic studies of foraging patterns and habitat use in fossil animals. For example, stable isotopes have shed light on the degree of 'aquatic-ness' of various early whale relatives, tens of millions of years ago.

larryo': Wasn't there something out of South Carolina about dietary habits of saber-tooths? Am I remembering correctly?

kenafd: Yes, I think you are referring to a study that looked at whether Pleistocene saber-toothed cats were hunting forest-dwelling or grassland herbivores. I don't recall the exact dietary breakdown.

larryo': It was the C4 or C3 photosynthesis in different sorts of plants that was the clue, I think.

kenafd: Yes, yes, good point. In that study the fossils were old enough that organic material (collagen) was not preserved, so the researchers were dependent upon the mineral fraction of bone, and thus a smaller suite of isotopes to work with. In terms of other paleoecological isotopic studies that have provided insight for modern conservation biology, those studies often rely upon good organic preservation in fossils - this allowing isotopic, ancient DNA, and radiocarbon analyses. For example, lots of work has been done fossils from permafrost deposits in AK, Yukon, Siberia. Because these bone have basically been frozen for the past ~25,000 years they are often fairly 'fresh.'

larryo': Ah. That makes sense. And you all these different ways to extract information. How does this compare to efforts to learn about bird migratory patterns today using stable isotopes? Is it similar just with living organisms?

kenafd: Yes, the more different tissues we have to work with, the more information we can gather. Clearly in modern organisms like birds we have access to all the soft stuff (like blood, muscle), in addition to inert tissues like feathers and toenails. Different tissues isotopically record different types of information - both in terms of diet and movement patterns.

larryo': But all this information ultimately is a window into the environment where the organism lives -- it's food, water, etc.? Right?

kenafd: Exactly! It's like we playing back an ecological tape-recorder; we can learn about what the animal has been eating, or where it has been living in general over the past day, month, or year - depending upon what types of tissues we analyze. Something like blood turns over quickly in the body, so by analyzing blood we get a short-term snapshot of more recent diet. But something like hair grows slowly over months, so by analyzing along the length of a hair we can gather a sequential record of ecological information.

larryo': Sounds lie there is far more information out there than folks know what to do with. Along those lines, what are you working on now?

kenafd: I've spent the past year studying the charismatic MICROfauna of a Kenya savanna... termites!

larryo': Very charismatic these days as folks look for ways to turn cellulose into fuel! What are you hoping to learn from them?

kenafd: I've learned a lot about how important they are to nutrient cycling in these savanna systems. They influence the distribution of nutrients in really obvious ways, such as collecting organic material in their nests, and in less obvious ways, such as controlling how much nitrogen Acacia trees fix from the atmosphere (Acacias are legumes - which means they are not solely dependent upon soil nitrogen like most other plants). Basically, termites are really, really important members of this ecosystem - some might even call them keystone species.

larryo': Is this something you are going to use to look back in time there -- old termite mounds??

kenafd: I get that question a lot! No, this work is grounded in the recent... but I've gotten interested in understanding some of these not-so-obvious interactions that regulate ecosystem-scale patterns of isotopic variability in modern systems. When we use isotopes to study fossil grassland ecosystems it's important that we have a sense of how things work in modern grasslands.

larryo': Otherwise the interpretation could be all off, right?

kenafd: Yes, until we build a time-machine, we'll never know if our interpretations of ancient systems are correct, but by doing lots of good groundtruthing research in modern systems we at least can make well-informed interpretations.

larryo': It's the old problem in paleoecology -- making sure it makes sense in the real world. I remember grappling with that as a paleo undergrad at UCSC. Now yo have much better tools!

kenafd: Paleoecological proxies like isotopic analyses are very powerful when applied conservatively and appropriately. But analytical techniques keep improving, so I think it's an exciting future for this field of research! How are you doing on time? I may need to run soon get ready for a mammal paleo class.

larryo': We can wrap up. Thanks for your help and time. I'll contact you by email for some additional sources. Oh, and I need a picture of you!

kenafd: Ok - sounds good. Just let me know what you need. And I'll dig up a photo.

larryo': Great. Appreciate it. Have a great day!

kenafd: You too! thanks for the chat.

Article posted April 27, 2009.

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