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Speaker Series by Semester Darwin Day 2018

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"The Past Isn't Dead: The Last 2 Million Years Can Help Biodiversity in the Next 100""The Past Isn't Dead: The Last 2 Million Years Can Help Biodiversity in the Next 100"jacquelyn-gill-past-isnt-dead<img alt="" src="/darwin-day-sub-site/PublishingImages/Darwin%20Day%202018/JacquelynGill.jpg" style="BORDER:0px solid;" /><p><strong>Jacquelyn Gill</strong></p><p><strong>Abstract: </strong>Climate change, extinction, and other threats facing our ecosystems are nothing new under the sun – we have a number of examples in the recent fossil record to draw upon as analogs. Understanding how yesterday's biodiversity responded to these "natural experiments" can help prepare us for the next century. In this talk, I'll share several examples, asking: 1) What determines extinction risk, and 2) What are the consequences of ice age extinctions and climate change for present-day biodiversity? The Pleistocene ice ages are a particularly good model, because our biodiversity experienced repeated, dramatic, and often abrupt climate changes. Despite this, there appear to have been little extinction due to climate change alone, which begs several questions: Were species really that resilient? Are we overestimating future extinction risk? Or have we just underestimated how prevalent climate-driven extinctions have really been in the recent fossil record?<br></p><p>In contrast, the extinction of ice age megafauna has been extensively studied, but until recently, most research has focused on the causes of that extinction (largely focusing on humans versus climate). However, we know much less about the long-term ecological legacies of those extinctions. This leads to the question: if a mammoth dies in the forest, what happens to the trees? Quite a lot, it turns out; large herbivores appear to buffer the impact of climate change on plants, and their removal had large-scale consequences for modern ecosystems that are still playing out today. These lessons from the past can help inform cutting edge—but often controversial—conservation strategies, from managed relocation of species to de-extinction and rewilding.</p>2018-02-12T05:00:00Z
"Were Fe-oxidizing microbes the earliest life on Earth?""Were Fe-oxidizing microbes the earliest life on Earth?" Fe-Oxidizing-Microbes<img alt="" src="/darwin-day-sub-site/PublishingImages/Darwin%20Day%202018/Clara%20Chan.jpg" style="BORDER:0px solid;" /><p><b>​Clara Chan</b></p><p><b>Abstract:<br></b>The first life on Earth was microbial, but the simplicity of single cells means that fossilized microbes are difficult to recognize. The exceptions are microbes that make minerals, or essentially, instantly fossilize. I will talk about how we study living Fe-oxidizing microbes in order to understand their biomineral morphologies, with examples from the Loihi Seamount submarine volcano and Rittenhouse Park in Newark, DE. Together we will apply these findings to evaluate images of millions- and billions-year old microfossils, including ones that are claimed to be the oldest life on Earth. I will also delve into how we use Fe-oxidizer isolate and environmental genomes and biochemistry in order to understand how these organisms have evolved special enzymes adapted to the challenges of making Fe oxide minerals. </p>2018-02-12T05:00:00Z
“Limits to DNA sequence variation in species with huge population sizes”“Limits to DNA sequence variation in species with huge population sizes”john-mcdonald-limits-dna<img alt="" src="/darwin-day-sub-site/PublishingImages/Darwin%20Day%202018/JohnMcdonald.jpg" style="BORDER:0px solid;" /><p><strong>John H. McDonald </strong></p><p><strong>Abstract:</strong><br>Many species, such as oysters, copepods, and sea squirts, have tremendous population sizes, with tens or hundreds of billions of individuals alive today. A body of mathematical theory that was developed over 50 years ago, the neutral model, has done a good job of describing most patterns of variation in DNA sequences within and between species. However, the neutral model predicts that species with very large populations will have very high levels of DNA sequence variation throughout most of their genomes. In fact, organisms with huge populations have about the same level of DNA variation as species with much smaller populations. This talk will review the possible explanations for this puzzling deviation from the neutral model, and it will suggest that natural selection acts against new mutations, even in seemingly non-functional regions of the genome, because too much genetic variation is a bad thing. </p>2018-02-12T05:00:00Z
“Keeping an Eye on Eye Evolution”“Keeping an Eye on Eye Evolution”salil-lachke-keeping-eye-evolution<img alt="" src="/darwin-day-sub-site/PublishingImages/Darwin%20Day%202018/SalilLachke2.jpg" style="BORDER:0px solid;" /><p><strong>Salil Lachke</strong></p><p><strong>Abstract:</strong><br>Ever since the publication of Charles Darwin's "Origin of Species" (1859), understanding the evolution of the eye – a sophisticated multicomponent organ – in diverse animals has been a challenging pursuit.  Indeed, more than a century passed before Walter Gehring demonstrated in 1996 that a single protein, Pax6, is sufficient to induce eye development in organisms as different as flies and vertebrates!  I will focus on the cutting-edge advances at University of Delaware that have identified new RNA-binding proteins essential for controlling gene expression in eye development across different vertebrates such as fish and mouse, and their relevance to human eye disease.</p>2018-02-12T05:00:00Z
"Darwin and Melville on the Galapagos""Darwin and Melville on the Galapagos"heyward-brock-melville-galapogas<img alt="" src="/darwin-day-sub-site/PublishingImages/Darwin%20Day%202018/HeywardBrock.jpg" style="BORDER:0px solid;" /><p><strong>D. Heyward ​Brock </strong></p><p><strong>Abstract:<br></strong>Both Darwin (1809-82) and Melville (1819-91) visited the Galapagos Islands within a few years of each other (1835 and 1841, respectively) and later wrote about what they discovered there (<em>Voyage of the</em> <em>Beagle </em>[1839] and <em>Origin of Species</em> [1859]; The <em>Encantada</em>s [1854]).  Although both observed the same place, their vastly different descriptions of what they perceived provide an illuminating example not only of their particular conceptual orientation and strengths as writers but also of some philosophical implications of theory and observation in general. </p>2018-02-12T05:00:00Z
"Eugenics and Adoption in 1950s Virginia: The Case of Georgia & David Rowe""Eugenics and Adoption in 1950s Virginia: The Case of Georgia & David Rowe"sarah-trembanis-eugenics-adoption<img alt="" src="/darwin-day-sub-site/PublishingImages/Darwin%20Day%202018/SarahTrembanis.jpg" style="BORDER:0px solid;" /><p><strong>​Sarah Trembanis</strong></p><p><strong>Abstract:<br></strong>The eugenics movement found a welcoming home in Virginia in the 1920s and persisted for decades.  Virginia eugenicists found in the precepts of the American eugenics movement a scientific legitimization of white supremacy.  By the 1950s, the eugenics movement had been tarnished by its connections to Nazism, yet the underlying supports persisted and had substantial implications for Virginian families.  This talk will focus on the story of a kinship adoption and the ways in which eugenic racial beliefs and policies nearly derailed it.</p>2018-02-12T05:00:00Z
"Evolutionary Cost of Healing""Evolutionary Cost of Healing"mike-moore-evo-cost-healing<img alt="" src="/darwin-day-sub-site/PublishingImages/Darwin%20Day%202018/MichaelMoore.jpg" style="BORDER:0px solid;" /><p><strong>Michael Moore​</strong></p><p><strong>Abstract:</strong> <br>To maximize their evolutionary fitness, organisms have to invest limited resources in a way that successfully balances competing demands for resources from growth, maintenance and reproduction. Natural selection has produced a variety of organismal lifestyles that balance these demands in different ways. For example, there are short-lived organisms that invest heavily in reproduction but little into maintenance and growth and there are long-lived organisms that do the opposite, investing heavily in growth and maintenance and relatively little into reproduction.  In addition, individual organisms face challenges every day that require them to make decisions about where to best invest their resources to maximize their fitness. We examined competing demands between a maintenance function, wound healing, and reproduction. Prior to these studies, there was little evidence that immune functions like wound healing placed much demand on limiting resources, especially energy. We were therefore surprised to discover that healing of relatively minor wounds caused animals to abort reproductive efforts to recover energy to use to heal the wounds. This suggests that activation of the immune system that is necessary for recovery from accident or disease is energetically costly. This discovery has consequences for our understanding of medical treatment of humans. In addition, it suggests that minor wounds received by animals during fighting or escaping from predators may be much more costly in both energetic and evolutionary terms than previously thought.</p>2018-02-12T05:00:00Z
The Books on the Beagle The Books on the Beagle Books-on-Beagle <img alt="" src="/darwin-day-sub-site/PublishingImages/Darwin%20Day%202018/LeslieK.Overstreet.jpg" style="BORDER:0px solid;" /><h4>This lecture examines the remarkable library Charles Darwin and Captain Fitzroy took with them on the famous round-the-world voyage of HMS <em style="font-size:1em;">Beagle </em><span style="font-size:1em;">in 1831-1836.</span></h4><h4><span style="font-size:1em;"><br></span></h4><h4><span style="font-size:1em;">Leslie K. Overstreet</span></h4><p>Curator of Natural-History Rare Books</p><p>Leslie K. Overstreet earned a B.A. in English Literature from Reed College (Portland, Oregon) in 1971 and a Master of Arts in Teaching (also from Reed, 1972) and held jobs as a teacher and a writer/editor before joining the Smithsonian Libraries (SIL) in 1980. Initially staffing the anthropology and vertebrate zoology libraries in the National Museum of Natural History, she earned an M.L.S. degree in rare-books librarianship at the University of Maryland and has worked in SIL’s Special Collections Department since 1988. As the Curator of Natural-History Rare Books, she has headed SIL’s Joseph F. Cullman 3rd Library of Natural History since it opened in 2002.</p><p>Her work includes assisting readers, answering reference questions, and giving tours of the collection; she oversees the Cullman's participation in the Biodiversity Heritage Library (<a href=""></a>),SIL's Adopt-a-Book program, and a wide variety of outreach and development events.  She works with SIL conservators to preserve the collection and with the scientists and historians whose research SIL supports to build and strengthen it.</p><p>Her own research has focused for many years on Mark Catesby’s <em>Natural history of Carolina, Florida and the Bahama Islands</em> (London, 1731-1743).She served as a consultant to the documentary film “The curious Mr. Catesby,” produced by the Catesby Commemorative Trust and broadcast on public-television stations across the U.S. in 2009, and presented the results of her research on the printing history of Catesby’s book at the 2012 Catesby Tercentennial Conference, which was subsequently published as a chapter in <em>The curious Mister Catesby</em> (University of Georgia Press, 2015). </p>2018-02-13T05:00:00Z

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