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Bayesian estimation of Ordovician dispersal pathways

 

Today was an exciting day for the lab.  The paper on Ordovician dispersal pathways led by Adriane Lam which incorporates her primary MS thesis research came out. This paper is exciting for several reasons.  First, it’s always great when a student gets their research published! Second, this is the first use of bayesian biogeographic modeling with Paleozoic taxa.  Third, this project represents an evolution beyond a MS thesis project, through collaboration and improvements with additional authors at other institutions, namely Nick Matzke.  I am really so thrilled with how this paper came out.  It is a landmark is methods and has important implications for understanding Ordovician biogeography.  The only downside…Adriane titled it “Dispersal in the Ordovician” as  play on “Pirates of the Carribean” so I can’t get the Pirates theme song out of my head….

Lam, A.R., Stigall, A.L, Matzke, N.J. 2018. Dispersal in the Ordovician: Speciation patterns and paleobiogeographic analyses of brachiopods and trilobites. Palaeogeography, Palaeoclimatology, Palaeoecology, 489: 147-165. Online

Key Points:

  • Bayesian and ML methods were successfully implemented with Ordovician taxa.
  • Founder event speciation was important in the evolution of Paleozoic taxa.
  • Taxa with different larval strategies responded similarly to climate shifts.
  • Ocean currents were key influences on invertebrate dispersal patterns.
  • Results indicate most evolution within clades occurred during climate shifts.

 

Science—what am I up to anyway?

Science—what am I up to anyway?

It’s occurred to me that I have been writing quite a bit about broadening participation in science lately and have not actually talked much about what science I have been up to. So here is a brief update about recent developments on that front.

At the IGCP 653 meeting in Yichang, China, I presented new research on some very interesting and rare fossils from the lower part of the Cincinnatian Series. Over the past few years, I have been very fortunate to receive a series of rare fossils collected by some of the fantastic amateur paleontologists of the Dry Dredgers in Cincinnati, Ohio. In particular, Ron Fine, has collected some intriguing brachiopods from the lower Cincinnatian Kope Formation (Edenian Regional Stage) that look like they belong to lineages otherwise only known as invasive taxa from the upper Cincinnatian (Richmondian Regional Stage). These pre-Richmondian “invaders” comprise an interesting set of species that shed light on invasion dynamics in the fossil record.

At Yichang, I argued that interbasinal species invasions (or immigrations) could be considered in a hierarchical context, with ranks including ephemeral invasion, incursion epibole, and biotic immigration events. I am currently expanding this invasion hierarchy into a full article for Annual Reviews in Ecology and Evolutionary Systematics. (AREES), so I won’t elaborate here, but I think this is a really exciting and potentially transformative concept about the assembly of diversity through time.

At the GSA meeting in Seattle, I am presenting research related speciation mechanisms and how we can move from a basic correlation of diversity with Earth systems events to a causal mechanism for increasing diversity based on the process of speciation. Much of the arguments for this talk are in press already within my Lethaia paper (here).

So…for the near term, these are the scientific questions that I am investigating and the questions that keep me up at night: how do we really resolve speciation processes in the fossil record, how can we use that information to understand diversification during the Ordovician Radiation/Great Ordovician Biodiversification Event, and how do invasions (of varying intensities) contribute to diversity patterns of life through time?*

*obviously these questions are best addressed with data about articulated brachiopods from the Ordovician Period

IGCP 653: Yichang Reflections

IGCP 653: Yichang Reflections

I’m currently on a 12 hour flight from Shanghai to Chicago as part of my 3 flight (and 29 hour) itinerary home from the 2nd Annual IGCP 653 meeting in Yichang, China. I can say, unreservedly, that this was a fantastic meeting!

Attendees included more than 60 delegates from 10 nations. The fact that most attendees were Chinese—and I am not—provided a wonderful opportunity for me to meet many new and upcoming scientists—both students and early career professionals that I have not previously had the opportunity to interact with. I was so impressed by the quality of their science and their ability to communicate at a high level on an international stage. What a talented group of young scientists! I am incredibly encouraged and inspired by them.

Of course, I was also able to reunite with (and meet new) colleagues from Europe, Africa, and North America as well. Truly this meeting met the spirit of UNESCO, our funding agency for the IGCP project, in terms of bridging international divides and fostering common interests and collaborations.

At this conference, provocative scientific ideas were espoused—generating substantial discussion, important geologic sections were visited (including the GSSPs for both the Hirnantian and Dapingian stages!), and cultural differences were both explored and celebrated. It’s exciting both how much we have learned about the Great Ordovician Biodiverisfication Event in terms of ocean chemistry, oxygenation patterns, diversity patterns of metazoans and also how much we have to learn—such as when did this event start and end, whether such things can be clearly defined, and what does that mean for the Earth system?

Speaking for myself, my favorite parts were probably the fact that we had an international assemblage of brachiopod workers to talk with (it’s great-and rare to be among people that love my favorite fossils as much as I do!) and that there were so many dynamic young female researchers in the group.

As anyone who is relatively close to me knows, I am very concerned with increasing participation in science on both a national and international level. I was so encouraged to see so many young and dynamic female scientists! Female students earned awards for both poster and oral presentations. This is pretty groundbreaking.

To place this in context, I had a conversation with a colleague, who I generally admire very much as a scientist, in which he said to me one evening {I’m paraphrasing} “You know, we always try to hire men instead of women for permanent jobs. You can’t say that in open meetings, but in secret meetings, we always say this.” I asked why this was the case and was told that it could be problematic for women to both be in charge of or be the majority of a field team to remote regions. I pushed back on this concept (I certainly was told the similar things as a grad student), and my friend said “Well, most women are not like you. They are not assertive and independent.” On one level, I was glad that my colleague appreciated that some women could be leaders, but it also made clear to me that there are many countries where women still need to fight hard to be considered scientific equals. I am not special. Female scientists need the chance to grow and shine and deserve the same support as our male colleagues.

The male student at our table noted that the female students work much harder and achieve higher levels of excellence than the male students. He sees the value in this contemporaries, and I am heartened that over time this view will win out…but I’d much rather we achieve equity in the near term and not wait 20 years and lose out on the great science these young women could have done by excluding them.

I hope that my work in the international community can help to foster a sense of empowerment for female (and other underrepresented) scientists in both the USA and other nations. At this meeting, I was assertive. I capitalized on my leadership as a co-chair of IGCP 653 role to be present, to chair sessions, to judge and present awards, to invite everyone to Athens, Ohio in 2018, and I hope that seeing one woman do that in a sea dominated by male leadership can help to inspire the fantastic and talented women that I met at this meeting to be assertive and empowered in their own scientific lives.

 

Nilmani passes her final defense!

by Alycia Stigall

Nilmani is now a Master of Science!  She successfully defended her thesis titled: Hierarchical Spatial Patterns in Paleocommunities of the Late Pennsylvanian Ames Limestone.  Nilmani did a really nice job in her thesis analyzing and interpreting regional vs. local differentiation in contemporanous shallow marine communities across southeastern Ohio.  Congratulations, Nilmani!

 

Reflections on the International Biogeography Society Meeting in Tucson: Celebrating diversity and deep time

Reflections on the International Biogeography Society Meeting in Tucson: Celebrating diversity and deep time

This post was initially written as a guest blog for the International Biogeography Society blog

The International Biogeography Society Biennial Conference is one of my favorite meetings to attend. These conferences consistently profile outstanding and cutting edge science, opportunities to interact with a set of colleagues that I don’t have the opportunity to see at my paleontology-centric conferences, and interesting destinations to explore. This year’s conference in Tucson hit the mark in all areas.

A key strength of IBS conferences is that they are fundamentally a celebration of diversity in many ways: diversity of approaches ranging from molecular to big data and ecological to phylogenetic frameworks; diversity of focal ecosystems and taxa; diversity of temporal lens from modern to deep time; diversity of nationalities and cultures; diversity of genders and identities. This diversity makes the scientific contributions and opportunities so much stronger. Developing such a diverse conference is not a coincidence, the IBS board and meeting organizers actively work to promote scientific and culture diversity. And the dedication and hard work pays off. For example, someone like me, who studies paleobiogeography of marine life from 400 million years ago feels at home with colleagues studying geographic structure of genetic variation in modern tree species.

From my perspective, two aspects of this year’s IBS conference particularly struck me: the increasing inclusion of a deep time perspective and fossil data and increasing recognition and participation of women in biogeography.

Each of the symposia featured at least one talk involving paleodata. The “Modeling large-scale ecological and evolutionary dynamics” symposium featured paleo data in nearly every talk and showcased a wide range of paleo data from historical records to the Pleistocene. Contributed sessions, posters, and mini-talks also prominently focused on the relevance of paleodata, including analyses that employed Paleozoic data to address questions relevant to modern biodiversity concerns (abstract book here).

Geologic and paleontological data, particularly the breakup of Pangaea and the waxing and waning of the Pleistocene ice sheets, have long been incorporated in biogeographic analyses. What was exciting about this meeting is the fact that paleodata beyond those two cases are being employed and being employed broadly within the field in many different contexts ranging from species distribution models, quantifying community functioning and species richness processes, and calibrating projections of biotic impacts of future climate changes.

Rising above this pervasive paleontological mist was the fact that the winners of the MacArthur & Wilson and the Alfred Russell Wallace Awards, Jessica Blois and Margaret Davis, are paleobiogeographers, which further underscores the significance that the field ascribes to research emphasizing fossil data.

Both awardees are also women, which leads to my second point. This meeting celebrated the accomplishments of outstanding women in biogeography, like Jessica and Margaret, and at the same time acknowledged and celebrated the additional hurdles and barriers that were (and still are) faced by women in science. Steve Jackson, in his citation of Margaret Davis, provided a wonderful discussion that contextualized some of the hurdles that Margaret faced as the sole women in pollen analysis, the significance of her indomitable spirit, and the inspiration she has provided to others.

Today, women are not usually alone in our departments or subdisciplines, but we and members of other underrepresented groups still face obstacles, additional requests on our time as token representatives, and implicit bias in reviews and in other contexts. But meetings like IBS, where a group of women met at 7:30 am over coffee to discuss shared issues and plan a support group and where we have lunch mentoring groups that discuss early career issues, provide clear and positive steps forward.

Women have been leaders in biogeography for many years, as evidenced by the Margaret Davis’s well deserved Wallace award, and women are poised to continue leading and innovating, as evidenced by female students winning 3 of 5 poster awards.

I ended the conference by raising my glass with a group of a dozen female paleobiogeographers. For me it was a fitting end to a conference that celebrated diversity of science, of timescales, and of individuals.

 

 

New paper showcasing current trends in biogeography

My colleagues and I recently published a horizon scan, a review of the current state of the field, of modern biogeography based on the International Biogeography Meeting held in Bayreuth, Germany in 2015.  Some of the key threads in this paper are the increasing prominence of large databases, integrated analyses, and inclusion of paleodata.

Dawson, M.N., Axmacher, J.C., Beierkuhnlein, C., Blois, J., Bradley, B., Cord, A.F., Dengler, J., He, K.S., Heaney, L.R., Jansson, R., Mahecha, M.D., Myers, C.E., Nogués-Bravo, D., Papadopoulo, A., Reu, B., Rodgríguez-Sánchez, F., Steinbauer, M., Stigall, A.L., Tuanmu, M-N. & Gavin, D.G. 2017. A Second Horizon Scan of Biogeography: Golden Ages, Midas Touches, and the Red Queen. Frontiers in Biogeography, 8(4), e29770. Online

It’s great to have this paper out, and just in time to revisit this concepts and explore how the field has changed at the upcoming International Biogeography Meeting in Tucson, Arizona next month.

Geological Society of America Reflections

It is difficult to describe this year’s GSA meeting in Denver.  Overall, it was a great meeting, full of the usual pride in my students’ accomplishments, joy of reuniting with colleagues including many Stigall Lab alumni, nervousness about my own talks, and thrill of learning about the newest developments in the science of paleontology.  But I will always remember this meeting for the Paleontological Society banquet.

bear

The Stigall lab was busy presenting cutting-edge science on a wide variety of topics. Current MS students Ranjeev Epa and Nilmani Perera gave excellent poster presentations about Oligocene freshwater gastropods from Tanzania and Pennsylvanian marine community ecology of Ohio, respectively.  Recent alumnus Sarah Trubovitz gave a talk about her MS work on Ordovician brachiopod paleoecology, and I spoke about the importance of alternating dispersal and vicariance regimes in biodiversity accumulation.

ranjeev nilmani
We had a great Stig*Allstars (=name my alumni gave themselves) dinner to kick off the meeting.  Getting together with this talented group of former students turned colleagues is always a highlight.  They are doing such amazing work as PhD students and early career scientists. I’m so very proud of them and excited to see where their careers will go.

img_6525 img_6530

This year’s GSA, however, was really special as I was awarded the Charles Schuchert Award for Excellence and Promise in Paleontology from the Paleontological Society.  This was the 45th time the Schuchert Award has been presented.  It was only the 5th time that a woman received the award, and the first time a woman with children was the recipient.  After receiving the award from the Paleontological Society president, Steven Holland, I was honored to be able to give a short acceptance speech to the nearly 400 paleontologists gathered at our annual banquet.  I focused my remarks on the challenges to women and minorities in paleontology alongside the standard series of thank you’s.  This the first time that increasing participation has been addressed specifically in an award speech, and I felt both very compelled and nervous about making these comments.  I am very glad that I did!  Continuing to engage in conversations about women and minority challenges are very important for continued progress in our (or any) discipline.

Stigall Schuchert Speech schuchert

The full text of my speech is below, and it will eventually be published in the Journal of Paleontology.

RESPONSE BY ALYCIA L. STIGALL
For the Charles Schuchert Award, 25 September 2016

Thank you, Bruce, for your generous words. I deeply thank the Paleontological Society for recognizing me with this honor. I truly am very grateful and humbled to be selected as the 2016 Schuchert Award recipient. As a brachiopod worker from Cincinnati, the Charles Schuchert award holds special significance to me. I am also deeply honored to now be included among the prestigious set of 44 prior awardees. It is particularly gratifying as I am only the fifth woman to receive this award, and first woman who was a mother at the time of the award.

I am extremely thankful to be a paleontologist today. Paleontology is becoming an ever more inclusive and collaborative science. As I look out from this podium, I see a wonderful diversity of paleontologists –diversity of scientific approaches, diversity of focal taxa, diversity of gender, diversity of ethnicities and nationalities. Our diversity makes our discipline stronger.

However, barriers to full and equitable participation in science for women and minorities remain considerable. Implicit bias, higher expectations, under recognition, harassment, and isolation remain substantial concerns. As a society and as individuals, we are taking positive steps to increase dialog, foster support groups, promote awareness, and tackle our own inherent biases. Like all women who continue in science, I have overcome such challenges in my career, but tonight I stand here excited and optimistic that the future of our discipline will be one of ever increasing inclusion.

I would not be here tonight without the support of my family, colleagues, and friends, and I’d like to take the rest of my time to recognize some of them. First I must thank my parents. As teachers, they have been steadfast in their support of my love for learning, rocks, and fossils. When I was a child, they took me to national parks in 47 states, they accompanied me to rock and mineral shows, gave me a copy of a 1962 Golden Guide to Fossils, and allowed me to disappear into the nearby stream to hunt fossils for hours at a time. Those early experiences surrounded by loving support gave me the confidence to truly pursue my goals and dreams.

As an undergraduate at the Ohio State University, I had the amazing good fortune to learn morphology and systematics (with a Swedish accent) from Stig Bergström who taught me the importance of deeply understanding a clade and of adopting promising new approaches during one’s career. Loren Babcock instilled in me a sense of boundless enthusiasm for prehistoric creatures. And Bill Ausich taught me how to be an excellent scientific citizen, the importance of loving your clade, and above all pursing excellence in science. I am so thankful for the enduring support of Bill and Stig, which has been instrumental in my development as a scientist.

I graduated from OSU with a career goal to resolve early arthropod phylogeny–but quickly reoriented my research interests to studying the complex impacts of biogeography and ecological change on macroevolutionary patterns. In graduate school at the University of Kansas, I worked on phyllocarid crustacean phylogenetics of my master’s thesis, but rapid realized the limitations of working on uncommon fossils for my research agenda. So I shifted my focal taxon to rhynchonelliform brachiopods, and I haven’t look back. (Although I greatly enjoy working with conchostracans from time to time) Brachiopods are truly awesome.

Throughout graduate school, Bruce Lieberman was amazing mentor in every dimension of the word. He taught me how to construct a project, how to succeed in publications, and the importance of perseverance. Even beyond graduate school, Bruce’s promotion of my career has been immeasurable, and I thank him very deeply.

In my twelve years at Ohio University, I have been privileged to work with very supportive colleagues in our Geological Sciences department, an immensely talented set of paleontologists sprinkled across campus, and fantastic collaborators in the Patton College of Education. Working in a department with the master’s as our terminal degree offering, I’ve had the distinct pleasure of working very closely with each of my graduate students. My greatest scientific joy has been mentoring and encouraging my students—now numbering 13—as they develop from scientific novices to confident, accomplished scientists conducting research publishable in top journals. I am very proud of them, and certainly wouldn’t be standing here before you tonight without this exceptional group of students turned collaborators, many of whom are here to support me tonight.

Although I did not know many women paleontologist as a student, I have benefitted greatly from knowing and learning from many amazing women as a professional. In particular Margaret Fraiser, Sandy Carlson, Brenda Hunda, Lisa Park Boush, Dena Smith, and Peg Yaccobucci have been co-conspirators and role models in various ways. I thank the women who trailblazed in the cohorts ahead of mine, and I am greatly inspired by the women in the junior cohorts behind me.

I also thank my colleagues outside of this room. My approach to science has been considerably broadened and enriched by collaborations with modern biogeographers and ecologists as well my international colleagues with whom I’ve studied fossils on all seven continents.

Finally, and most importantly, I must thank my husband, Dan Hembree, who has been my partner in this journey since our first day of graduate school at Kansas. He has always believed in me, even when I did not. His friendship, laughter, encouragement, and discussions have made my science and my life so much richer, and I can’t imagine either without out him. Lastly, our children Max and Josie make everything awesome. It has been invigorating to re-explore the wonders of fossils through their young eyes.

Thank you again, to the members and Council of Paleontological Society for this recognition. I will strive to fulfill the promise inherent in this award and serve our community well in the years to come.

Species-level diversity curve for Middle Ordovician Laurentian brachiopods published in GEOLOGY

Congratulations to alumnus Sarah Trubovitz on the publication of her MS thesis research in GEOLOGY!   **clicking this link bypasses the paywall, so click here!

Also, this is the first official publication of IGCP 653: Onset of the Great Ordovician Biodiversification Event. Our project is off to a great start!

 

Synchronous diversification of Laurentian and Baltic rhynchonelliform brachiopods: Implications for regional versus global triggers of the Great Ordovician Biodiversification Event

The profound global impact of marine radiations during the Great Ordovician Biodiversification Event (GOBE) is widely appreciated; however, diversification varied among paleocontinents and these individual trajectories are less understood. Here we present a new species-level diversity curve for rhynchonelliform brachiopods from midcontinental Laurentia based on bed-by-bed analysis of the Simpson Group of Oklahoma (USA).

Ordovician meets the Anthropocene @ ESA

Ordovician meets the Anthropocene @ ESA

IMG_5997For my final adventure of the summer, I traveled to Ft. Lauderdale, Florida to present an invited talk about lessons learned from invasive species in the fossil record at the Ecological Society of America (ESA) meeting.  I was very honored to be part of an exciting symposium titled: “Ecological novelty in the Anthropocene: Are novel communities novel ecosystems?” convened by Jacquelyn Gill and Alejo Ordonez.

The organizers did a wonderful job of arranging a series of presenters who explored the issue of ecosystem novelty from multiple perspectives including conceptually, experimentally, and policy implications.  My talk (abstract here) provided the deep time context and an exploration of what does novel mean within a non-human context.

As a scientist who studies the deep history of life (~450  million years ago), I am always very cognizant of the different lenses with which we can study and discuss patterns at varying temporal scales.  One of the key concepts that was emphasized, particularly in the panel discussion at the end of the session, was that novelty is continuously being produced.  Earth does not now, and never has, existed in a steady state for extended temporal intervals.  So it is extremely important to consider consequences and definitions when attempting to generate a conservation plan.  What is it that you are attempting to conserve?  Is it a species?  Is it ecosystem services? It is energy flow and functioning?  These are incredibly important questions that must be answered by policy makers.  They are also the types of issues that the fossil record can help to provide insight into as well.
In addition to the formal session, I had the opportunity to spend time with some of the other speakers over meals and down time.  I made some new colleagues with potential new collaborations, and learned quite a bit about various areas of ecology that will help me to consider my paleontological questions with new eyes and insights.  This was my first time to an ESA meeting, and I hope it will not be my last.IMG_6011

Side notes: Poolside hammocks and bar at the ESA hotel were a nice touch! And the place was crawling with Magicarp and Psyduck (which I dutifully captured for my kids, right for my kids).

 

Early summer = field reconnaissance

Early summer = field reconnaissance
Springtime flowers atop the 550 outcrop

The best part of Spring semester ending is the flexibility of schedule to head into the field!  Relatedly, Nilmani and I have spent several days scouting field sites for her MS thesis examining paleoecology of the Ames Limestone.  The Ames is an extremely well-known marker bed throughout the Appalachian Basin and has been the subject of many petrological, faunal, and ecological analyses over the years.  Nilmani’s project will add to this body of knowledge by examining how community structure varies at multiple spatial scales.

Armed with a productive year of preliminary analyses and background study, Nilmani is ready to tackle her main research this summer.  Step 1 is identifying outcrops.  We’ve visited over a dozed previously described locations throughout Athens, Hocking, Morgan, Noble, Muskingum Counties.  Some sites are extremely promising for her thesis work.  Others, not so much.

Overall, we’ve had a lot of fun exploring the rocks, fossils, wildflowers, wildlife, and general region of SE Ohio.  And as always, perhaps my favorite parts of “spring training” is having solo time in the car and field to really get to know my students.