Friday, September 20, 2019

Isotopes in Bird Feathers reveal their diet and geo-location

Seth Newsome and Gary Graves, Santeetlah Creek Watershed, 2013
         One of my favorite projects with Seth Newsome that sparked my interest in geoecology was a collaboration with Gary Graves, Curator of Birds, at the Natural History Museum of the Smithsonian. Gary is known as a “hard-ass” dude in ornithology. I’ve seen his prickly nature when he reviewed a paper we coauthored and he found the statistical treatment of the analyses insufficient. With Seth and me, I’ve seen the other side of him. In the field when we collected warblers, plants, insects, and water, Gary is completely switched on to the ecology of the region. As a native of the state of Arkansas, on the drives to the field areas, he likes to imitate Bill Clinton and tell jokes about all manner of things. In the rural North Carolina town where we stayed, we enjoyed breakfast and sweet tea at the local McDonalds with the senior citizens and chicken fried steaks in local restaurants for dinner. We had a lot of laughs throughout the collaboration gossiping about colleagues, reviews, and science. This collaboration is a good example of something that has held great importance in my career—the enjoyment of meeting and working with new, smart people.

         Seth and I had read papers by Hobson et al. (1997) and Rubenstein (2002) and had become intrigued by their results on bird migration. By measuring the hydrogen isotopes in a bird’s feather, one can ostensibly figure out the geographical region where that bird grew the feather. For birds that migrate from North America to the Caribbean and back each year, scientists are curious if the birds return to the exact place year after year. Bird-banding, placing a small band around a bird’s leg with an identifying number, allows scientists to determine that indeed some birds return to within 100 meters of where they had been the year before.

         Graves had collected (i.e. killed and stuffed) thousands of Black-throated Blue warblers in a decade long study of their breeding habits and ecology. Our collaboration with Gary has lasted over 10 years. We began with a series of feathers collected from warblers that were sampled along a latitudinal gradient from northern Georgia into southern Canada. Collaborating with Matthew Betts (Oregon State University), we analyzed hundreds of hydrogen isotope values from 22 sites ranging from 34 to 46 degrees North latitude. There was a clear influence of latitude on the hydrogen isotope composition of feather keratin with more positive values measured in the south and more negative values from the north.

Seth (left) and Gary Graves (Right) 2013

    The samples included adult birds and juveniles in their second year of life.  Black-throated Blue warblers migrate each fall from continental North America to tropical islands in the Caribbean, where they spend the winter.  They fly north again in spring to breed and molt their feathers. Our initial research question was the following: did Black-throated Blue warblers juveniles return to where they had been born or did they strike out for new territory?  We found that, with very few exceptions, juvenile Black-throated Blue warblers returned to the same general region where they were born. This work prompted further studies.

         Graves had colleagues at Chicago’s Field Museum with freezers full of Great Gray Owls, one of the largest birds in North America. These birds leave their territories in Canada and Alaska and invade the lower 48 states periodically, probably in response to a lack of prey. Once here, they still face dangers. During the winter of 2004-2005, 265 owls were killed in Minnesota alone by vehicular collisions. We sampled tissues from this unprecedented collection of avian specimens and published our work on carbon and nitrogen values of muscle, liver, and feathers (Graves et al., 2012). Muscle tissue analyses showed greater nutritional stress and a poor body condition. Nitrogen isotopes of muscle showed that the owls potentially spanned three trophic levels.

         The carbon and nitrogen data were interesting, but the hydrogen isotope data on feathers revealed much more. Hydrogen isotopes of animal tissue are determined from the hydrogen coming from an animal’s diet (i.e., organically bonded hydrogen) as well as drinking water (Estep and Dabrowski, 1980; Hobson et al. 1999, Newsome et al., 2017). Drinking water hydrogen isotopes are generally considered to be similar to that of precipitation and are dependent on latitude, altitude, and distance from the ocean. Hydrogen isotopes in plants are also primarily influenced by precipitation. Herbivores show an enrichment of the heavy hydrogen (2H) relative to plants. The hydrogen isotopes in diet are a combination of lipids (isotopically more negative), carbohydrates (isotopically more positive), and proteins (variable). Carnivorous birds, two to three trophic steps above plants, have much more positive hydrogen isotope values in their feathers than do herbivorous birds. 
Hydrogen isotope data from Great Gray Owls

         Great Gray Owls eat small mammals, placing them at least two and perhaps three trophic levels, above plants. These owls invaded northern tier of states south of Canada in late October, were found on roadsides, and were collected throughout the winter and spring until mid-May. We questioned whether owls arriving earlier were from nearby regions of Canada vs. those coming from colder, more mountainous western regions. We measured the greatest range in hydrogen isotope compositions from owls collected in February.

         We estimated that in February, owls arrived from parts of Canada extending from maritime Canada in the east to the Canadian Rocky Mountains and Northwest Territories to the west. Wow! Owl invasions happen only periodically. It remains unknown as to why Great Gray Owls from across the entire continent pull up stakes and fly south.

         Much of this work remains unpublished, both for the warblers and the owls. Why? Although we submitted an article on the warblers—twice—it was rejected both times because reviewers wanted us to assign a more exact geographic location for each specimen based on its isotope composition. I don’t feel this is a valid reason for not accepting a manuscript. My co-authors were disheartened, as people often are, when a paper is rejected. I continue to hope the data will be published in its entirety soon. We countered these reviews by measuring hydrogen isotopes in even more feathers.

         Graves undertook special collections in 2012 and 2013 taking 20 specimens in each year. From each bird, he sub-sampled 25 different feathers—primaries, secondaries, tail feathers, and body feathers. We found that the variation in hydrogen isotopes within one bird could be almost as great as the variation expected from birds living from Georgia to Pennsylvania. Based on these data and on data from 12 years of sampling birds at Santeetlah watershed, it’s evident to me that there is inherently more complexity built into the isotope signal than just geo-location. The diet of the bird and the weather that year are significant drivers of isotopic compositions of bird feathers, providing a much more interesting glimpse into their ecology.

Butterfly collecting Seth Newsome, 2012
         Seth, Gary and I continued to work on Black-Throated Blue warblers specifically in the Santeetlah Creek watershed of rural, mountainous North Carolina. We wanted to document all of the steps of the bird’s food chain from water to plants to caterpillars finally to birds. During our fieldwork, we noticed a specific species of butterfly, the Pipevine Swallowtail that could be found throughout the watershed. Hence, I am proud to say that we were “butterfly collecting”, a derogatory term people use for scientists who don’t have a serious enough research agenda. It felt good to collect some of these butterflies, the caterpillars that metamorphose into them, and the host plants. The analyses continue to this day.
Santeetlah Creek Watershed, Pipevine in right center

Thursday, September 19, 2019

Living with ALS as it progresses


Daughter Dana Swarth and Marilyn 2016
            This week is my 67th birthday. I suspect I’ll have another couple birthdays unless my condition changes drastically. Since my diagnosis of ALS three years and 4 months ago, every day brings small challenges and my life has ups and downs on almost an hourly basis. In so many ways, I can’t complain. I have a close and loving family, dear friends around the world, a bank account balance that’s positive, and a prestigious academic position. I still enjoy eating good food, can manage a nice glass of wine or one cocktail, can talk, think, and type. I have relatively little pain—my butt gets sore when I sit in one position too long. I just need to stand and shuffle.
Marilyn (with necessary walker) and Maryjo Brounce, UCR EDGE event 2017
            For the past four months son Evan Swarth has been making a movie about my journey with ALS. It's a labor of love. I had the idea of a 5-minute video. He turned that into a major movie production for him with his Apple computer, iPhone, and a Sony digital camera. We recorded over 80 minutes of conversation with just me alone. He interviewed several others. The result is a 25-minute documentary (https://www.youtube.com/watch?v=yRhpFoUFMyA&feature=youtu.be) that I hope will inspire and inform you. People ask often how they can help. Not only do we enjoy getting casseroles and homemade cookies, but it means a lot to me for people to read about ALS and learn something about the disease. Your support buoys me—daily. Here’s what a progressive disease means for me now.
Every month for 3 years I've been tracking the disease progression--I'm lucky

            The concept of privacy means different things to different people. It’s enormously important to me as I transition from independence to dependence. My privacy for many things is still intact, but it’s eroding in fits and spurts. I like to spend time alone and always have. Even though I might present as an “extrovert”, I need time by myself to connect with my inner self, think things over. 
            Privacy also concerns what other people know about you. Early on, I decided that my medical challenges were easier for me to disclose than to try to keep them private and quiet. For a person who was physically active and independent, it bothers me that people might think that I’m weak or don’t take care of myself. As my physical frame slumps, and my muscles whither away, I’d much rather people know what I’m facing.
Marilyn and Chris, Death Valley 2017, it was easier to travel then
            Life’s most basic needs are no longer done in privacy. Showering requires help to get in and out of a shower chair. Although I can still lift my arms to wash everything, I can see the horizon approaching for a shift in self-sufficiency. My husband is, at this point, the only person assisting me au natural. With others, I don a big T-shirt to cover up 90%. I never was very comfortable with public bathrooms at the YMCA. My modesty remains intact. Shifting away from modesty and privacy requires serious personal adjustment.
Evan with Fogel Endowed Chair of Geoecology
            Using the toilet, a subject NO ONE discusses past the age of 3 or 4, is something I find myself discussing with an ever-wider group of people—with this blog now the “world”. I am still able to maneuver to the john on my own, but require ever more complex assistance with adaptive devices. At UC Riverside, Jeanette Westbrook, assistant for the EDGE Institute, and I have a procedure that is carefully choreographed. It involves my standing and sitting four times and two rides in the wheelchair. I use what I term the “Fogel Endowed Chair of Geo-Ecology”—an elevated potty seat that Jeanette first places over the commode allowing me to then independently sit, do my “business”, and then stand. The restroom door is shut, but no longer locked after postdoc Kaycee Morra needed to climb under a locked door to rescue me. When Chris and I travel, we have a folding potty chair in the back seat of our car and a transfer belt in case I need help standing. The bathrooms in two of our houses have had accessible risers and handles installed. I treasure my privacy here. It will require patience and strength for my caregivers when this privacy ends. It will require an adjustment to my physical sphere. It will be tough.
            But I’m still kickin’. In the past couple of years, I’ve lost several good friends and family to cancer, heart disease, stroke, and despair. This troubles me. I was the person who was supposed to be dying—not those healthy people. Therein lies my conundrum. I have a wealth of good things in my life balanced by the very real decline heading towards the end of life.
            I have no fear about the end of my life.
            I fear—sometimes crippling fear—about the journey I’m going to have to take to get to the end. The fear isn’t always rational. Chris is in this relationship for the long haul. Dana and Evan are in touch constantly. They’ve responded by changing their lives around these past three years. My wish is for them to live happy productive years and get their lives established. I’ve hired the first of probably many home health caregivers. The adjustment to a “stranger” taking care of your most intimate—and private—needs takes getting used to. Keeping fear from holding sway over my days requires vigilance. Mastering fear requires distraction—writing helps—music works.
Dana, Marilyn, and Evan, Alaska, 2017, Roughrider wheelchair
            My slow decline has had its benefits. I’ve managed to help students, colleagues, friends, and family with advice and mentoring in this time I’ve been granted. I’ve provided some financial help to those in need. I have the time to wind my career down slowly, methodically, like I’d like it to happen. I’ll be able to say goodbye, something my sister wasn’t able to do.
Lab group: Jon Nye, Jeanette Westbrook, Bobby Nakamoto, Kaycee Morra, Patrice Barnett, Ying Lin, 2019
            I’ve been able to take the time to see and talk to people before the end. With visits from people around the world, the connections I’ve personally made have sustained me. The daily emails, the comments on the blog, and now this week with the release of Evan’s movie, I thank all of you for enriching my life. Even the annoying, difficult, pain in the ass situations—taken together with those good times—keep the fear in check. Thanks to all for coming along on my journey.
Seal Beach, 2019, Sand wheelchair!

Tuesday, September 17, 2019

Career Advancement and Forging a new career


Office at Geophysical Lab prior to move

Horner-Devine et al., 2016. “Community and empowerment are necessary for individuals to leverage their scientific training, skills, and expertise into successful and impactful careers. To advance diversity in STEM, we must change the ways we support women scientists and scientists from other underrepresented groups as they embark on their careers, and we must develop strategies that create a sense of community and empowerment...By creating opportunities to foster community building and empowering all our early-career scientists, especially women and underrepresented minorities, we can foster a scientific culture in which all our scientists can thrive.”

         Although women are now seriously considered for academic positions, several roadblocks are still in place. Many articles have been written about the problems (Holmes et al., 2015) often referring to a “leaky pipeline” in which trained women scientists drop out along the career path, such that few attain senior status. I knew the dangers first hand. With my first husband, there was constant pressure to give it all up and live in a cabin in the woods. While searching for a full-time academic position, the rejections were enough to convince anyone they should settle for a lab assistant’s job. With motherhood, the pressure from society and family to stay home was present. Certainly, keeping up long hours at the lab were no longer possible. And although I was in a stable, understanding relationship, it was a constant balancing act. I was comfortable at the Geophysical Lab for 30 years and made little effort to further my career beyond growth in research contributions. Things changed when my son was about to leave for university and the possibility of leading the Geophysical Lab opened up in 2009.

         I wonder how my career might have advanced if I were a man. In 2008, I put my name forward to be considered for the Director of the Geophysical Laboratory. I understood the operation of the Lab, knew everyone on campus and in the Institution including the President, and was reaching some prominence in my field of biogeochemistry, astrobiology, and geobiology. For final consideration, there was only one other candidate, my colleague Russell Hemley. Rus is a member of the National Academy of Science (and at that time, I was not), has published more than 400 papers, and had brought in millions of dollars from external grants. A committee was appointed to review “the candidates” and at first, it was comprised of only men. After a complaint was lodged with Carnegie’s President, one woman was appointed. As candidates, we submitted a 2-3 page statement and our CV. There was one interview with the committee, and none with the staff or the administration. We did not give a special seminar. When President Meserve made his decision, he picked Rus Hemley, who on paper was eminently “more qualified” than me. To achieve what I have, I was convinced that I had to pour more energy into aspects of my career than did my male colleagues.  Aspects of early career disadvantages remain even today. Are there roadblocks to administrative leadership that women are more vulnerable to than men?
New Horizons for Marilyn, sunset Oklahoma on drive to California

         In response, I decided to build some administrative credentials and was selected to be a Program Director at the National Science Foundation in Geobiology and Low Temperature Geochemistry. Many researchers reach a point where they want to explore new challenges.  Administrative leadership is a common line of career expansion sought in academia.  After my stint at NSF, I learned a few important things about myself and about women in science. One, pure science credentials--a good reputation, lab skills, great postdocs and students, and consistent funding--are not enough for advancement into administrative leadership. Leadership is viewed as being Director, Chair, Dean, Provost, or President. Anything less than this, doesn’t count. Two, I am first and foremost a scientist, not a bureaucrat, and I’m good at the creative aspects of science and research. Personnel management and paper shuffling is not my strong suit, jobs often delegated to administrative leaders. Three, I should have made the effort earlier in my career to get “leadership” experience. As a woman, this is required. 
New house in Mariposa, California

         I returned to the Geophysical Lab in 2010. When my husband, a native Californian, said he was more than ready to move across the country back to his beloved natal state, I took the opportunity to cast a wide net to see where I might contribute in a university setting. By 2012 I had interviewed and obtained an offer at the University of California Merced, where I was offered the opportunity to provide leadership while doing research and formal classroom teaching. In January 2013, Chris and I “jumped ship” and headed to California. 
Boxes in new UC Merced laboratory January 2013

Winter in the "Olden Days"

  Greenvale Raiders: Marilyn, Albert Stein, Freddy, David Fuhrman, 1960 My mother claimed, and rightly so, that she walk...