Introducing BEACON’s New Science Outreach and Communication Postdocs

Alexa Warwick out in the field at night with her study organism, the Pine Barrens Treefrog.

This post is by MSU postdoc Alexa Warwick.

Alexa Warwick is the new Evolution Education and Outreach Postdoc at BEACON working with Dr. Louise Mead.

Alexa worked on her Ph.D. with Drs. Emily Lemmon and Joseph Travis at Florida State University focusing on the ecology, evolution, and conservation of the Pine Barrens Treefrog (Hyla andersonii; Fig. 1). At BEACON, she will be coordinating three established outreach programs that were previously run by Dr. Jory Weintraub. These annual programs include the Darwin Day Roadshow, Ecology and Evolution events at the National SACNAS Conference, and the Undergraduate Diversity Travel Award to attend the Evolution meetings (this year in Austin, TX; award applications due April 18th!). The programs are collectively sponsored by BEACON, the Society for the Study of Evolution, the Society of Systematic Biologists, and the American Society of Naturalists.

Fig 1. The Pine Barrens Treefrog has a unique species distribution across three isolated regions in the eastern United States.

In addition to these national outreach programs, Alexa will also be involved with developing and assessing other outreach/education projects. One of these projects is an efficacy study of Data Nuggets in high school biology classes. Data Nuggets are an exciting way to introduce K-16 students to real scientists and authentic research data, while also helping scientists increase their broader impacts. Alexa is passionate about effectively engaging students and the general public with science research, so feel free to contact her with other ideas for outreach/education collaborations!

She will also be continuing to do research on amphibians while at BEACON. For example, she is working with Dr. Elise Zipkin’s lab at MSU and SPARC-net, a regional group working to understand climate and land use change on salamander population dynamics. For this project salamander sampling plots will be established at the Kellogg Biological Station and the data collected there will be combined with similar plots across the northeastern United States.

A gladiator frog (Hypsiboas pugnax) that Alexa caught in the lowlands of Colombia.

Alexa’s other research interests include studying the evolutionary history of organisms using genomic data (phylogeography/phylogenetics) and the effects of behavioral interactions on the evolution of species (sexual selection). Her work on the Pine Barrens Treefrog has addressed the origin and maintenance of its unique distribution (Fig. 1), and she has recently started working with gladiator frogs (genus: Hypsiboas) in South America. This is a fascinating group of frogs with rather unusual behaviors; they actually get their common name from the male-male combats that occur using a spine on their ‘thumbs’. Check out Alexa’s website for more details about current research projects or send her an email at awarwick [at] msu.edu.

Also check out our other two previous New Science Outreach and Communication Postdocs posts by Wendy Smythe and Travis Hagey

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A Mighty Mouse and a Scientist in Training: A Story of Physiological and Personal Evolution

This post is by Okemos High School student Maddie Stover working in Dr. Ashlee Rowe’s lab in the Neuroscience Program & Department of Integrative Biology at MSU.

A particularly effective nervous system makes the four-inch grasshopper mouse quite a fearsome desert creature, especially if you are an arthropod. Not only do these rodents howl to defend their territory and stalk their prey like big cats, but they hunt venomous scorpions, centipedes, and tarantulas. Yet these arthropod preys are not without a strong defense; their venom contains potent neurotoxins that are designed to both incapacitate and induce intense pain in their predators. In an evolutionary arms race, grasshopper mice (Onychomys​ spp.), when compared to house mice, exhibit reduced sensitivity to the pain caused by bark scorpion (Centruroides​ spp.) venom (1). Our lab is investigating the molecular and physiological adaptations to the nervous system of grasshopper mice that confer resistance to bark scorpion venom. Three species of grasshopper mice are distributed throughout the deserts and prairies of North America; I study the Chihuahuan desert species, Mearns’ grasshopper mouse (O​. arenicola)​. Specifically, I am interested in the adaptations underlying their resistance to the venom of the striped bark scorpion (C​. vittatus)​.

A grasshopper mouse attacking a bark scorpion. Photo by Dr. Matthew Rowe.

Pain signals are transmitted to the central nervous system (CNS) by way of ion channels embedded in cell membranes. Sodium (Na+) and potassium (K+) ion channels play an important role in pain-signaling. As these channels are essential for many physiological processes they are very well conserved, such that a few amino acid substitutions can produce a significant change in the overall electrical activity of the channels. Bark scorpion venom contains low-molecular-weight proteins (toxins) that bind and manipulate ion channels, causing intense pain. Rowe et al. (2) previously showed that the Sonoran desert grasshopper mouse (O​. torridus)​ is resistant to the burning pain of its local prey, the Arizona bark scorpion (C​. sculpturatus)​, via amino acid changes to a pain-pathway Na+ channel (Nav1.8). Instead of inhibiting toxin binding to its target channel (Nav1.7), amino acid substitutions in O. torridus​ Nav1.8 enable the channel to bind a protein in C​. sculpturatus​ venom, ultimately blocking the pain signal the venom is trying to send to the CNS (2). However, O. arenicola a​ppear to be resistant to C. vittatus​ venom through an alternative mechanism. Since C. vittatus​ venom contains many K+ channel toxins, our lab is looking at the structure and function of O​. arenicola K​ + channels to determine whether changes in these ion channels confer reduced pain sensitivity to C. vittatus​ venom.

A potassium channel consisting of an alpha subunit (red) and a beta subunit (blue). Pongs, O. & Schwarz, J.R. (3).

In addition to providing an opportunity to study evolution at the molecular level, the grasshopper mouse model might also have interesting implications for chronic pain. Currently, opioids are the most common medication used to treat chronic pain. However, these drugs can have unpleasant side effects and become addictive. In order to develop better treatments for chronic pain, a more detailed understanding of the ion channels involved in pain-signaling is required. In the grasshopper mouse model we are able to study the physiological effects of structural variation in different types of potassium channels that regulate pain-signaling.

When I first came to the Rowe Lab I was interested in how the structure and function of K+ channels contributed to the grasshopper mouse’s decreased sensitivity to toxin-induced pain. As I continued reading about these channels I found that K+ channels (the main pore region of which is called the alpha subunit) assemble with various auxiliary subunits. Beta subunits (a type of auxiliary unit) are cytoplasmic proteins that help regulate the channel’s electrical activity (3). Beta subunits are also the targets of certain scorpion toxins. At the Rowe Lab, I am studying whether K+ channel beta subunits contribute to the grasshopper mouse’s resistance to scorpion toxins.

To investigate this question I sequenced two genes that encode K+ channel beta subunits from O. arenicola.​ I also cloned these genes so that we may coexpress K+ channel alpha and beta subunits in a heterologous system, and record the electrical activity of this channel complex. I found structural variation, when compared to house mouse orthologs, in both beta subunits I am studying. Currently, we are testing whether these structural changes have functional consequences for the K+ channel that contribute to grasshopper mouse venom resistance.

BEACON-Maddie workingI have had a great first experience with research at the Rowe Lab. All of our lab members have been important mentors to me and have taught me so much. My lab helped me transition from a high school setting to a professional one (their patience, god bless) where I could learn skills that will be helpful in any area of work. I have learned that problem solving really is as big of a deal as they make of it on college websites and to never be ashamed to ask for help. I have learned that you really do regret what you do not write down, that white boards are the most important piece of equipment, and that I can really freak my grad students out by talking about my birth year.

As previously stated beta subunits are small (the gene is around 2,000 base pairs long) when compared to alpha subunits (the gene is ~8,000 base pairs long). They are also quite new to molecular biology, as they were discovered in 1992. I suppose I am analogous to a beta subunit in that we are both relatively small and new to science.

References

  1. Rowe, A.H. & Rowe, M.P., 2008. Physiological resistance of grasshopper mice (Onychomys spp.) to Arizona bark scorpion (Centruroides exilicauda) venom. T​ oxicon,​ 52(5), pp.597–605.
  2. Rowe, A.H. et al., 2013. Voltage-gated sodium channel in grasshopper mice defends against bark scorpion toxin. Science,​ 342(6157), pp.441–446.
  3. Pongs, O. & Schwarz, J.R., 2010. Ancillary Subunits Associated With Voltage–Dependent K+ Channels. P​ hysiological Reviews,​ 90, pp.755–764.
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Deputy Director Charles Ofria Receives College of Engineering Withrow Distinguished Scholar Senior Award

Left to right: Erik Goodman (BEACON Director), Charles Ofria (BEACON Deputy Director), Leo Kempel (MSU College of Engineering Dean)

BEACON is very excited to congratulate our Deputy Director Charles Ofria on his selection for the College of Engineering Withrow Distinguished Scholar Senior Award. This is the MSU College of Engineering’s highest award for research and a significant achievement. The award is presented annually to one senior faculty member. A committee selects awardees after receiving nominations from all departments within the College of Engineering. In introducing Prof. Ofria for presentation of the award, BEACON Director Erik Goodman reviewed many of Prof. Ofria’s professional accomplishments, and noted especially his key role in generating the BEACON concept that led to its funding. Prof. Ofria continues to play a large role as Deputy Director and a leader of many projects. As Prof. Goodman stated, “Without Charles, there would be no BEACON.”

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A niche in time: adaptations in sensory processing associated with temporal niche

Andrea Morrow

MSU graduate student Andrea Morrow

This post is by MSU graduate student Andrea Morrow.

People often associate certain physical adaptations with an animal’s temporal niche, i.e. daily activity pattern. For example, some nocturnal animals have larger eyes, larger corneas, or higher concentrations of rod cells than diurnal animals [1]. These traits are valuable for animals that are awake and active at night because they augment the collection and utilization of what little light is available, which is advantageous when it comes to avoiding predators and finding resources. While these adaptations may be valuable, nervous tissue involved in processing sensory information requires a large amount of energy to develop, maintain, and power [2]. For this reason, it might not be a great idea for a nocturnal animal to invest extensive amounts of energy into processing complex visual information, when the amount of information obtained will always be restricted due to lack of light. Let’s think of the flip side to that. Would a diurnal animal, with plenty of light available, profit more than a nocturnal animal from expending substantial energy in visual processing?

In general, if the energetic cost is high, then the reward should also be high, or else the trait will not be maintained [3]. We can apply this concept of costs and benefits to all sensory processing. Brain size is constrained by energetic costs [4], and therefore we expect energetic trade-offs when it comes to investments in specific areas or tasks. How do nocturnal vs diurnal animals utilize visual, tactile, olfactory, and auditory cues from their environment? Are some more heavily relied upon by diurnal animals, and less by nocturnal animals? If, as I suspect, diurnal animals invest more in visual processing than nocturnal animals do, does it come at a cost in the form of other sensory processing?

Dr. Barbara Lundrigan (Department of Integrative Biology), Dr. Laura Smale (Department of Psychology), and I are trying to answer some of these questions by examining multiple sensory processing structures within the brain. We want to determine whether investment trade-offs between olfactory, visual, and auditory processing occur following evolutionary shifts in activity pattern.

Focal group

Determining the effect of a single factor in an observational study can be a heady task, especially when it comes to complex brain structures. Ecological, behavioral, and phylogenetic factors all work in shaping brain morphology and functionality. We are sampling widely across the order of Rodentia (which includes more than 2,000 extant species) in order to include species that vary in life history, behavior, environment, and evolutionary history. Within this broad framework, we are sampling closely related species within multiple subfamilies where temporal niche transitions have occurred independently. For example, with our colleague Dr. Paul Meek, we are sampling Australian bush rats (nocturnal) and Australian swamp rats (diurnal) from the family Muridae. We are also sampling Southern flying squirrels (nocturnal) and North American red squirrels (diurnal) from the family Sciuridae. Both of these groups have independently experienced activity pattern shifts. We want to capture as many independent evolutionary shifts as possible, as well as including animals that exhibit activity patterns other than strict nocturnality and diurnality. Our working list currently includes about 30 different species from 10 subfamilies, representing several independent shifts. We have collected tissue samples from 13 species and over 80 individuals to-date.

Structures of interest

Two coronal sections of an Australian rat. The top image is stained with Cresyl Violet. The bottom image is a section stained with Acetylcholinesterase. The Medial Geniculate Nucleus (MGN) is outlined and shaded in blue and the Lateral Geniculate Nucleus (LGN) is outlined and shaded in black.

The goal is to quantify the investment in olfactory, visual, and auditory processing. For olfactory processing, we are measuring the weight of the olfactory bulbs, relative to the weight of the entire brain, in each individual. For visual and auditory processing, we are measuring the volume of the Lateral Geniculate Nucleus and specific layers of the Superior Colliculus, which are visual processing structures, and the Medial Geniculate Nucleus and the Inferior Colliculus, which function in auditory processing. We do this by cryosectioning the frozen, unfixed brain tissue of each animal. The tissue is stained using two types of stain (Cresyl Violet and Acetylcholinesterase), microphotographs of each tissue section are taken and uploaded to the computer, and then each structure is delineated. These histological methods allow us to measure the area of each structure on each section of brain tissue, which we then use to calculate volume.

Our objective is to better understand how animals utilize the different sensory cues in their environment, as well as how investment in the processing of that information changes with the evolution of different activity patterns. While we don’t have data on the visual and auditory structures yet, we have collected some data on the olfactory bulbs. While the data are preliminary and represent only 13 species, with 1-6 individuals each, differences in relative olfactory bulb size between nocturnal and diurnal species are already apparent. The nocturnal species possess larger olfactory bulbs, relative to brain size, than the diurnal species. In addition to adding more species, we plan to look more thoroughly at the olfactory system in relation to activity pattern in the future.

I’ve always been interested in how organisms adapt to their environments and how their morphology and physiology are shaped (or constrained) by their evolutionary history and ecology. It is intriguing to imagine one environment (spatially) being separated temporally simply by the rotation of the earth and the ensuing cycles of light. The temporal niche presents many unanswered questions. What changes occur when animals adapt to a new temporal niche? Are these changes consistent and predictable? What conditions permit or restrict temporal partitioning? Is competition a driving force of this type of niche shift? Must there be plasticity, or flexibility, in activity pattern present for such shifts to occur, and if so, at what level? I’m hoping that, in time, I will be able to answer at least a few of these questions.

References

[1] Kirk EC. 2006. Effects of activity pattern on eye size and orbital aperture size in primates. Journal of Human Evolution. 51:159-170.

[2] Mink JW, Blumenschine RJ, Adams DB. 1981. Ratio of central nervous system to body metabolism in vertebrates: its constancy and functional basis. American Physiological Society. 241:R203-R212.

[3] Niven JE, Laughlin SB. 2008. Energy limitations as a selective pressure on the evolution of sensory systems. Journal of Experimental Biology. 211:1792-1804.

[4] Barrickman NL, Lin MJ. 2010. Encephalization, expensive tissues, and energetics: An examination of the relative costs of brain size in Strepsirrhines. American Journal of Physical Anthropology. 143:579-590.

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How lemur social networks shape microbial transmission

This post is by UT Austin graduate student Amanda Perofsky.

Amanda Perofsky holding a sedated Verraux’s sifaka in 2012. The Sifaka Research Project at Ankoatsifaka Research Station captures animals periodically to mark them with collars, monitor health, and collect genetic material.

Primates exhibit diverse ecological and behavioral patterns, ranging from solitary foragers to several hundred individuals, as in the multi-level societies of hamadryas baboons [1]. Many wild primates live in social groups that range from stable to highly fluid, and this has important implications for the transmission of viruses, bacteria, and parasites between individuals. Several studies have demonstrated that host contact patterns alter the course of disease spread in wildlife populations [e.g., 2–6]. However, the effects of social contacts on commensal and mutualistic microorganisms, such as the mammalian gut microbiome, are just beginning to be appreciated [e.g., 3–5].

As a PhD student in Dr. Lauren Ancel Meyers’ research group at UT-Austin, my research aims to better understand the impact of primate social behavior on susceptibility to intestinal bacteria, and to identify factors that shape the gut microbiomes of individuals, social groups, and populations. In particular, I study Verreaux’s sifaka (Propithecus verreauxi), an endangered lemur species, in close collaboration with Dr. Rebecca Lewis, a primatologist in the Department of Anthropology at UT. Verreaux’s sifaka, like all lemurs, are unique to Madagascar, an island country off the southeastern coast of Africa. Dr. Lewis has studied sifaka behavior for over twenty years and directs the Ankoatsifaka Research Station located in Kirindy Mitea National Park in southwestern Madagascar. To distinguish between individuals, Dr. Lewis has fitted the sifaka at her field site with nylon collars and tags. One adult female in each social group has a radio collar, which enables researchers to locate specific groups in the forest using a radio transmitter.

A sifaka social group sunbathing in Kirindy Mitea National Park, Madagascar.

Sifaka live in small, tight-knit social groups that feed, sleep, rest, and travel together. Physical contact that promotes bacteria transmission may occur when sifaka groom each other, co-feed in trees, and huddle together. Within a social group, some pairs spend more time grooming each other than others [10]. Because sifaka (like all lemurs) groom with their mouths and toothcombs, do close grooming partners exchange intestinal bacteria more frequently compared to sifaka that rarely interact? Additionally, some individuals groom everyone in their social group, whereas others have only one or two close relationships. Are these highly social sifaka exposed to a greater diversity of microbes?

An unmarked sifaka grooms an adult female with infant nursing.

To answer these questions, I examine both sifaka social network structure and bacterial communities in sifaka fecal samples. Based on the behavioral data recorded by Dr. Lewis and her field assistants, I construct social network models that represent potential microbe-transmitting social contacts that occur within and between social groups. Social network models provide an intuitive framework for visualizing a population as a set of individuals (or, “nodes”) connected by “edges” [11] that, in this context, represent pathways for bacteria transmission.

In 2012, I traveled to Madagascar to collect fecal samples from each sifaka in the Ankoatsifaka study population and will be returning this summer to collect more samples. Each morning, we use a radio transmitter to locate the social group we’ll be following for the day. Collecting the fecal samples can be exasperating at times, and I couldn’t have accomplished my 2012 field season without the generous help of my collaborator, Elvis Rakatomalala, a Malagasy PhD student at the University of Antananarivo. Even with two people, it can be difficult to follow a large social group when the lemurs are jumping away in every direction and defecating all at the same time in different places. The fecal pellets scatter as they hit branches and leaves on the way down to the ground. We then crawl on our hands and knees through scratchy thorns, looking for pellets the size of Tic Tacs in the leaf litter. Once we locate a sample, we record the GPS point, the date, and the sifaka’s identity, and then put the pellets in a tube with liquid that preserves the DNA. The rest of the research— DNA extraction, bacteria sequencing, and data analysis— takes place back at UT.

After describing my fieldwork as difficult at times, why would I travel across the world to collect lemur fecal samples? Although collecting lemur fecal samples isn’t always easy, I love working outside surrounded by the forest,, and it’s fascinating to observe animals that can’t be found anywhere else in the world. Being in the field and collecting the samples myself gives me a deeper intuition for sifaka social behavior and its potential epidemiological consequences, providing insights that wouldn’t occur to me if I were at my desk in Austin.

  1. Griffin, R. H. & Nunn, C. L. 2011 Community structure and the spread of infectious disease in primate social networks. Evolutionary Ecology 26, 779–800.
  2. Böhm, M., Palphramand, K. L., Newton-Cross, G., Hutchings, M. R. & White, P. C. L. 2008 Dynamic interactions among badgers: implications for sociality and disease transmission. Journal of Animal Ecology 77, 735–745.
  3. Hamede, R. K., Bashford, J., McCallum, H. & Jones, M. 2009 Contact networks in a wild Tasmanian devil (Sarcophilus harrisii) population: using social network analysis to reveal seasonal variability in social behaviour and its implications for transmission of devil facial tumour disease. Ecology letters 12, 1147–57.
  4. Clay, C. A., Lehmer, E. M., Previtali, A., St Jeor, S. & Dearing, M. D. 2009 Contact heterogeneity in deer mice: implications for Sin Nombre virus transmission. Proceedings of the Royal Society B-Biological Sciences 276, 1305–1312.
  5. Craft, M. E., Volz, E., Packer, C. & Meyers, L. A. 2011 Disease transmission in territorial populations: the small-world network of Serengeti lions. Journal of the Royal Society Interface 8, 776–86.
  6. Rushmore, J., Caillaud, D., Matamba, L., Stumpf, R. M., Borgatti, S. P. & Altizer, S. 2013 Social network analysis of wild chimpanzees provides insights for predicting infectious disease risk. The Journal of Animal Ecology , 976–986.
  7. Tung, J., Barreiro, L. B., Burns, M. B., Grenier, J.-C., Lynch, J., Grieneisen, L. E., Altmann, J., Alberts, S. C., Blekhman, R. & Archie, E. A. 2015 Social networks predict gut microbiome composition in wild baboons. eLife 4.
  8. Moeller, A., Foerster, S., Wilson, M., Pusey, A., Hahn, B. & Ochman, H. 2016 Social behavior shapes the chimpanzee pan-microbiome. Science Advances.
  9. Bull, C. M., Godfrey, S. S. & Gordon, D. M. 2012 Social networks and the spread of Salmonella in a sleepy lizard population. Molecular Ecology 21, 4386–4392.
  10. Lewis, R. J. 2010 Grooming patterns in Verreaux’s sifaka. American Journal of Primatology 72, 254–261.
  11. Newman, M. 2010 Networks: An Introduction. Oxford University Press.

 

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