Life Sciences Commons^™

Kin Selection And Its Discontents, David C. Queller

Biology Faculty Publications & Presentations

Kin selection is a core aspect of social evolution theory, but a small number of critics have recently challenged it. Here I address these criticisms and show that kin selection remains an important explanation for much (though not all) social evolution. I show how many of the criticisms rest on historical idiosyncrasies of the way the field happened to develop, rather than on the real logic and evidence.

The Promise And Pitfalls Of Β-Diversity In Ecology And Conservation, Jonathan A. Myers, Joseph A. Lamanna

Biology Faculty Publications & Presentations

A key challenge in ecology and conservation is to determine how processes at different scales create variation in community composition (β-diversity). In this issue, Oldén & Halme show that grazers increase β-diversity through multiple processes at different scales. We discuss how β-diversity can elucidate fundamental processes of community assembly, challenges in linking processes to patterns, and unresolved questions across scales.

Problems Of Multi-Species Organisms: Endosymbionts To Holobionts, David C. Queller, Joan E. Strassmann

Biology Faculty Publications & Presentations

The organism is one of the fundamental concepts of biology and has been at the center of many discussions about biological individuality, yet what exactly it is can be confusing. The definition that we find generally useful is that an organism is a unit in which all the subunits have evolved to be highly cooperative, with very little conflict. We focus on how often organisms evolve from two or more formerly independent organisms. Two canonical transitions of this type—replicators clustered in cells and endosymbiotic organelles within host cells—demonstrate the reality of this kind of evolutionary transition and suggest conditions that …

Phytochrome B Integrates Light And Temperature Signals In Arabidopsis, Martina Legris, Cornelia Klose, E Sethe Burgie, Cecilia Costigliolo Rojas Rojas, Maximiliano Neme, Andreas Hiltbrunner, Philip A. Wigge, Eberhard Schäfer, Richard D. Vierstra, Jorge J. Casal

Biology Faculty Publications & Presentations

Ambient temperature regulates many aspects of plant growth and development, but its sensors are unknown. Here, we demonstrate that the phytochrome B (phyB) photoreceptor participates in temperature perception through its temperature-dependent reversion from the active Pfr state to the inactive Pr state. Increased rates of thermal reversion upon exposing Arabidopsis seedlings to warm environments reduce both the abundance of the biologically active Pfr-Pfr dimer pool of phyB and the size of the associated nuclear bodies, even in daylight. Mathematical analysis of stem growth for seedlings expressing wild-type phyB or thermally stable variants under various combinations of light and temperature revealed …

Msl1 Is A Mechanosensitive Ion Channel That Dissipates Mitochondrial Membrane Potential And Maintains Redox Homeostasis In Mitochondria During Abiotic Stress, Chun Pong Lee, Grigory Maksaev, Gregory S. Jensen, Monika W. Murcha, Margaret E. Wilson, Mark Fricker, Ruediger Hell, Elizabeth S. Haswell, A Harvey Millar, Lee J. Sweetlove

Biology Faculty Publications & Presentations

Mitochondria must maintain tight control over the electrochemical gradient across their inner membrane to allow ATP synthesis while maintaining a redox-balanced electron transport chain and avoiding excessive reactive oxygen species production. However, there is a scarcity of knowledge about the ion transporters in the inner mitochondrial membrane that contribute to control of membrane potential. We show that loss of MSL1, a member of a family of mechanosensitive ion channels related to the bacterial channel MscS, leads to increased membrane potential of Arabidopsis mitochondria under specific bioenergetic states. We demonstrate that MSL1 localises to the inner mitochondrial membrane. When expressed in …

Purification Of 26s Proteasomes And Their Subcomplexes From Plants, Richard S. Marshall, David C. Gemperline, Richard D. Vierstra

Biology Faculty Publications & Presentations

The 26S proteasome is a highly dynamic, multisubunit, ATP-dependent protease that plays a central role in cellular housekeeping and many aspects of plant growth and development by degrading aberrant polypeptides and key cellular regulators that are first modified by ubiquitin. Although the 26S proteasome was originally enriched from plants over 30 years ago, only recently have significant advances been made in our ability to isolate and study the plant particle. Here, we describe two robust methods for purifying the 26S proteasome and its subcomplexes from Arabidopsis thaliana; one that involves conventional chromatography techniques to isolate the complex from wild-type …

Plastid Osmotic Stress Influences Cell Differentiation At The Plant Shoot Apex, Margaret E. Wilson, Matthew Mixdorf, R Howard Berg, Elizabeth S. Haswell

Biology Faculty Publications & Presentations

The balance between proliferation and differentiation in the plant shoot apical meristem is controlled by regulatory loops involving the phytohormone cytokinin and stem cell identity genes. Concurrently, cellular differentiation in the developing shoot is coordinated with the environmental and developmental status of plastids within those cells. Here, we employ an Arabidopsis thaliana mutant exhibiting constitutive plastid osmotic stress to investigate the molecular and genetic pathways connecting plastid osmotic stress with cell differentiation at the shoot apex. msl2 msl3 mutants exhibit dramatically enlarged and deformed plastids in the shoot apical meristem, and develop a mass of callus tissue at the shoot …

Theory Of Inclusive Fitness, David C. Queller

Biology Faculty Publications & Presentations

A review of Social Evolution and Inclusive Fitness Theory: An Introduction. By James A. R. Marshall. Princeton (New Jersey): Princeton University Press. $39.95. xix + 195 p.; ill.; index. ISBN: 978-0-691-16156-3. 2015.

Autophagic Turnover Of Inactive 26s Proteasomes In Yeast Is Directed By The Ubiquitin Receptor Cue5 And The Hsp42 Chaperone, Richard S. Marshall, Fionn Mcloughlin, Richard D. Vierstra

Biology Faculty Publications & Presentations

Highlights

• The yeast 26S proteasome is degraded by Atg8-mediated autophagy
• Nitrogen starvation and inactivation stimulate proteaphagy via distinct pathways
• Proteasome inhibition is accompanied by extensive ubiquitylation of the complex
• Proteaphagy engages the Cue5 autophagy receptor and the Hsp42 chaperone

Summary

The autophagic clearance of 26S proteasomes (proteaphagy) is an important homeostatic mechanism within the ubiquitin system that modulates proteolytic capacity and eliminates damaged particles. Here, we define two proteaphagy routes in yeast that respond to either nitrogen starvation or particle inactivation. Whereas the core autophagic machineries required for Atg8 lipidation and vesiculation are essential for both routes, the upstream Atg1 …

D-Place: A Global Database Of Cultural, Linguistic And Environmental Diversity, Kathryn R. Kirby, Russell D. Gray, Simon J. Greenhill, Fiona M. Jordan, Stephanie Gomes-Ng, Hans-Jörg Bibiko, Damián E. Blasi, Carlos A. Botero, Claire Bowern, Carol R. Ember, Dan Leehr, Bobbi S. Low, Joe Mccarter, William Divale, Michael C. Gavin

Biology Faculty Publications & Presentations

From the foods we eat and the houses we construct, to our religious practices and political organization, to who we can marry and the types of games we teach our children, the diversity of cultural practices in the world is astounding. Yet, our ability to visualize and understand this diversity is limited by the ways it has been documented and shared: on a culture-by-culture basis, in locally-told stories or difficult-to-access repositories. In this paper we introduce D-PLACE, the Database of Places, Language, Culture, and Environment. This expandable and open-access database (accessible at https://d-place.org) brings together a dispersed corpus of …

Discrete But Variable Structure Of Animal Societies Leads To The False Perception Of A Social Continuum, Dustin R. Rubenstein, Carlos A. Botero, Eileen A. Lacey

Biology Faculty Publications & Presentations

Animal societies are typically divided into those in which reproduction within a group is monopolized by a single female versus those in which it is shared among multiple females. It remains controversial, however, whether these two forms of social structure represent distinct evolutionary outcomes or endpoints along a continuum of reproductive options. To address this issue and to determine whether vertebrates and insects exhibit the same patterns of variation in social structure, we examined the demographic and reproductive structures of 293 species of wasps, ants, birds and mammals. Using phylogenetically informed comparative analyses, we found strong evidence indicating that not …

Tree-Mycorrhizal Associations Detected Remotely From Canopy Spectral Properties, Joshua B. Fisher, Sean Sweeney, Edward R. Brzostek, Tom P. Evans, Daniel J. Johnson, Jonathan A. Myers, Norman A. Bourg, Amy T. Wolf, Robert W. Howe, Richard P. Philllips

Biology Faculty Publications & Presentations

A central challenge in global ecology is the identification of key functional processes in ecosystems that scale, but do not require, data for individual species across landscapes. Given that nearly all tree species form symbiotic relationships with one of two types of mycorrhizal fungi – arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi – and that AM- and ECM-dominated forests often have distinct nutrient economies, the detection and mapping of mycorrhizae over large areas could provide valuable insights about fundamental ecosystem processes such as nutrient cycling, species interactions, and overall forest productivity. We explored remotely sensed tree canopy spectral properties to …

Sex Ratio And Gamete Size Across Eastern North America In Dictyostelium Discoideum, A Social Amoeba With Three Sexes, Tracy Edwards Douglas, Joan E. Strassmann, David C. Queller

Biology Faculty Publications & Presentations

Theory indicates that numbers of mating types should tend towards infinity or remain at two. The social amoeba, Dictyostelium discoideum, however, has three mating types. It is therefore a mystery how this species has broken the threshold of two mating types, but has not increased towards a much higher number. Frequency-dependent selection on rare types in combination with isogamy, a form of reproduction involving gametes similar in size, could explain the evolution of multiple mating types in this system. Other factors, such as drift, may be preventing the evolution of more than three. We first looked for evidence of …

The Coursesource Bioinformatics Learning Framework, Sarah C.R. Elgin, Anne Rosenwald, Mark A. Pauley, Lonnie Welch, Robin Wright, Jessamina Blum

Biology Faculty Publications & Presentations

No abstract provided.

Fine-Scale Spatial Ecology Drives Kin Selection Relatedness Among Cooperating Amoebae, Jeff Smith, Joan E. Strassmann, David C. Queller

Biology Faculty Publications & Presentations

Cooperation among microbes is important for traits as diverse as antibiotic resistance, pathogen virulence, and sporulation. The evolutionary stability of cooperation against “cheater” mutants depends critically on the extent to which microbes interact with genetically similar individuals. The causes of this genetic social structure in natural microbial systems, however, are unknown. Here, we show that social structure among cooperative Dictyostelium amoebae is driven by the population ecology of colonization, growth, and dispersal acting at spatial scales as small as fruiting bodies themselves. Despite the fact that amoebae disperse while grazing, all it takes to create substantial genetic clonality within multicellular …

Kin Discrimination In Dictyostelium Social Amoebae, Joan E. Strassmann

Biology Faculty Publications & Presentations

Presentation delivered at the symposium Evidence of Taxa, Clone, and Kin Discrimination in Protists: Ecological and Evolutionary Implications, VII European Congress of Protistology, University of Seville, 5–10 September 2015, Seville Spain.

Evolved cooperation is stable only when the benefactor is compensated, either directly or through its relatives. Social amoebae cooperate by forming a mobile multicellular body in which, about 20% of participants ultimately die to form a stalk. This benefits the remaining individuals that become hardy spores at the top of the stalk, together making up the fruiting body. In studied species with stalked migration, P. violaceum, D. purpureum, and …

A Parallel G Quadruplex-Binding Protein Regulates The Boundaries Of Dna Elimination Events Of Tetrahymena Thermophila, Christine M. Carle, Hani S. Zaher, Douglas L. Chalker

Biology Faculty Publications & Presentations

Guanine (G)-rich DNA readily forms four-stranded quadruplexes in vitro, but evidence for their participation in genome regulation is limited. We have identified a quadruplex-binding protein, Lia3, that controls the boundaries of germline-limited, internal eliminated sequences (IESs) of Tetrahymena thermophila. Differentiation of this ciliate’s somatic genome requires excision of thousands of IESs, targeted for removal by small-RNA-directed heterochromatin formation. In cells lacking LIA3 (ΔLIA3), the excision of IESs bounded by specific G-rich polypurine tracts was impaired and imprecise, whereas the removal of IESs without such controlling sequences was unaffected. We found that oligonucleotides containing these polypurine tracts formed …

Crystal Structure Of Deinococcus Phytochrome In The Photoactivated State Reveals A Cascade Of Structural Rearrangements During Photoconversion, E Sethe Burgie, Junrui Zhang, Richard D. Vierstra

Biology Faculty Publications & Presentations

Phytochromes are photochromic photoreceptors responsible for a myriad of red/far-red light-dependent processes in plants and microorganisms. Interconversion is initially driven by photoreversible isomerization of bilin, but how this alteration directs the photostate-dependent changes within the protein to actuate signaling is poorly understood. Here, we describe the structure of the Deinococcus phytochrome photosensory module in its near complete far-red light-absorbing Pfr state. In addition to confirming the 180° rotation of the D-pyrrole ring, the dimeric structure clearly identifies downstream rearrangements that trigger large-scale conformational differences between the dark-adapted and photoactivated states. Mutational analyses verified the importance of residues surrounding the bilin …

When Does Intraspecific Trait Variation Contribute To Functional Beta-Diversity?, Marko J. Spasojevic, Benjamin L. Turner, Jonathan A. Myers

Biology Faculty Publications & Presentations

Summary

1. Intraspecific trait variation (ITV) is hypothesized to play an important role in community assembly and the maintenance of biodiversity. However, fundamental gaps remain in our understanding of how ITV contributes to mechanisms that create spatial variation in the functional-trait composition of communities (functional Β-diversity). Importantly, ITV may influence the perceived importance of environmental filtering across spatial scales.
2. We examined how ITV contributes to functional Β-diversity and environmental filtering in woody plant communities in a temperate forest in the Ozark ecoregion, Missouri, USA. To test the hypothesis that ITV contributes to changes in the perceived importance of environmental filtering across …

Insights From A Convocation: Integrating Discovery-Based Research Into The Undergraduate Curriculum, Sarah C.R. Elgin, Gita Bangera, Sean M. Decatur, Erin L. Dolan, Laura Guertin, Wendy C. Newstetter, Elvyra F. San Juan, Mary A. Smith, Gabriela C. Weaver, Susan R. Wessler, Kerry A. Brenner, Jay B. Labov

Biology Faculty Publications & Presentations

The National Academies of Sciences, Engineering, and Medicine organized a convocation in 2015 to explore and elucidate opportunities, barriers, and realities of course-based undergraduate research experiences, known as CUREs, as a potentially integral component of undergraduate science, technology, engineering, and mathematics education. This paper summarizes the convocation and resulting report.