Life Sciences Commons^™

Displaying To Females May Lower Male Foraging Time And Vigilance In A Lekking Bird, Sarah A. Cowles, Robert M. Gibson

School of Biological Sciences: Faculty Publications

Males of many species use courtship behavior to attract mates. However, by doing so males may face the associated costs of increased energetic expenditure, reduced foraging time, and elevated predation risk. We investigated the costs of display in lekking male Sharp-tailed Grouse (Tympanuchus phasianellus). We used lek-wide scan sampling to study how males allocated time among courtship display (‘‘dancing’’), agonism, foraging, and inactivity in relation to female numbers both within and across days. We also addressed the limited attention hypothesis and estimated visual attentiveness by videotaping 13 males and scoring head turns during these different activities. We found that the …

Whole-Genome Sequencing Of Kshv From Zambian Kaposi’S Sarcoma Biopsies Reveals Unique Viral Diversity, Landon N. Olp, Adrien Jeanniard, Clemence Marimo, John T. West, Charles Wood

Nebraska Center for Virology: Faculty Publications

Kaposi’s sarcoma-associated herpesvirus (KSHV) is the etiological agent for Kaposi’s sarcoma (KS). Both KSHV and KS are endemic in sub-Saharan Africa where approximately 84% of global KS cases occur. Nevertheless, whole-genome sequencing of KSHV has only been completed using isolates from Western countries—where KS is not endemic. The lack of whole-genome KSHV sequence data from the most clinically important geographical region, sub-Saharan Africa, represents an important gap as it remains unclear whether genomic diversity has a role on KSHV pathogenesis. We hypothesized that distinct KSHV genotypes might be present in sub-Saharan Africa compared to Western countries. Using a KSHV-targeted enrichment …

The Use Of Journaling To Assess Student Learning And Acceptance Of Evolutionary Science, Lawrence C. Scharmann, Wilbert Butler Jr.

Department of Teaching, Learning, and Teacher Education: Faculty Publications

Journal writing was introduced as a means to assess student learning and acceptance of evolutionary science in a nonmajors’ biology course taught at a community college. Fourteen weeks of instruction were performed, each initiated by student-centered, in-class activities and culminated by a discussion, to elucidate tentative conclusions based on evidence from in-class activities. Students (N = 31) engaged in explicit and reflective writing (i.e., journaling) at four points during the semester, providing responses to the following questions: (a) what influence did the recent inclass activities and discussion have on your understanding of evolution (b) has your view (of evolution) changed …

Response Of Mammalian Macrophages To Challenge With The Chlorovirus Atcv-1, Thomas M. Petro, Irina V. Agarkova, You Zhou, Robert H. Yolken, James L. Van Etten, David D. Dunigan

Nebraska Center for Virology: Faculty Publications

It was recently reported that 44% of healthy humans in a study cohort had DNA sequences similar to Chlorovirus ATCV-1 (family Phycodnaviridae) in oropharyngeal samples and had decreases in visual processing and visual motor speed compared with individuals in whom no virus was detected. Moreover, mice inoculated orally with ATCV-1 developed immune responses to ATCV-1 proteins and had decreases in certain cognitive domains. Because heightened IL-6, nitric oxide (NO), and ERK MAP kinase activation from macrophages are linked to cognitive impairments, we evaluated cellular responses and viral plaque forming units in murine RAW264.7 and primary macrophages after exposure to …

Current Status Of The Northern Long-Eared Myotis (Myotis Septentrionalis) In Northwestern Nebraska, Keith Geluso, Patricia Freeman, Cliff Lemen

Transactions of the Nebraska Academy of Sciences and Affiliated Societies

The Northern Long-eared Myotis (Myotis septentrionalis; Order: Chiroptera) occurs in eastern, southern, and northern Nebraska, but its current distribution in northwestern parts of the state is unclear due to its recent arrival to the region. We investigated the status of this species in the Pine Ridge via mist net (2011-2014) and acoustic surveys (2014). We documented nine species of bats in the region, including M. septentrionalis. Of 423 total bats, M. septentrionalis was represented by four individuals, the fewest of all species during our four-year survey. We only documented M. septentrionalis in Sheridan County; …

Exploring The Influence Of Ancient And Historic Megaherbivore Extirpations On The Global Methane Budget, Felisa A. Smith, John I. Hammond, Meghan A. Balk, Scott M. Elliott, S. Kathleen Lyons, Melissa I. Pardi, Catalina P. Tomé, Peter J. Wagner, Marie L. Westover, Christopher E. Doughty

School of Biological Sciences: Faculty Publications

Globally, large-bodied wild mammals are in peril. Because “megamammals” have a disproportionate influence on vegetation, trophic interactions, and ecosystem function, declining populations are of considerable conservation concern. However, this is not new; trophic downgrading occurred in the past, including the African rinderpest epizootic of the 1890s, the massive Great Plains bison kill-off in the 1860s, and the terminal Pleistocene extinction of megafauna. Examining the consequences of these earlier events yields insights into contemporary ecosystem function. Here, we focus on changes inmethane emissions, produced as a byproduct of enteric fermentation by herbivores. Although methane is ∼200 times less abundant than carbon …

Ecology And Morphology Of The Late Miocene Musk Deer, Longirostromeryx Wellsi (Artiodactyla: Moschidae: Blastomerycinae), Katheryn Y. C. Chen

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Longirostromeryx wellsi, one of the latest surviving members of the extinct clade Blastomerycinae (Artiodactyla: Moschidae), possesses highly derived craniodental morphology that deviates from typical musk deer form. Previous work suggests that the unique anatomy of L. wellsi represents adaptations for occupying open savannas. To test this hypothesis I conduct principal components analysis on five postcranial bones of L. wellsi, comparing them to that of several extant ruminant artiodactyls, which are divided among seven habitat categories. These elements are also compared with the postcrania of other blastomerycines. These analyses indicate that L. wellsi anatomy is most similar to that of other …

A Dual Function Of White Coloration In A Nocturnal Spider Dolomedes Raptor (Araneae: Pisauridae), Tai-Shen Lin, Shichang Zhang, Chen-Pan Liao, Eileen A. Hebets, I-Min Tso

Eileen Hebets Publications

Nocturnal animals frequently possess seemingly conspicuous color patterns that can function in a variety of ways (e.g. prey attraction, camouflage, predator avoidance, etc.). The use of color patterns in intraspecific signaling, especially reproductive activities, in nocturnal animals has received relatively little attention. This study tested for a dual function of color in the nocturnal fishing spider, Dolomedes raptor (Araneae: Pisauridae), whose males develop dimorphic white stripes at sexual maturation. We tested for a role in foraging as well as mate assessment. First, quantifications of the natural variation of male stripes indicated a correlation between stripe area and male body size …

Kaposi’S Sarcoma-Associated Herpesvirus Transmission And Infection Among Young Zambian Children, Landon Olp

School of Biological Sciences: Dissertations, Theses, and Student Research

Kaposi’s sarcoma-associated herpesvirus (KSHV) is the etiologic agent for all forms of Kaposi’s sarcoma (KS)—one of the most common pediatric cancers in sub-Saharan Africa during the AIDS epidemic. KS was endemic in sub-Saharan Africa prior to the HIV/AIDS epidemic, but KS cases drastically increased thereafter. Our laboratory previously observed that KSHV infection is common among Zambian children and saliva is the major route of transmission. However, additional factors associated with the transmission of KSHV to children are poorly understood. Since a vaccine against KSHV is not currently available, it is paramount to understand factors associated with transmission so that alternative …

Influence Of Native And Processed Cereal Grain Fibers On Gut Health, Junyi Yang

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Cereal fibers that can be metabolized by gut microbiota have been shown to promote the growth of beneficial bacteria in the gut. Increased consumption of cereal fibers may improve host / gut microbiota interactions in obesity and other metabolic diseases by normalizing gut dysbiosis. The present dissertation describes four research projects to assess the impact of cereal dietary fibers on gut microbiota and host metabolism. In the first study, we determined the treatment temperatures for production of soluble, non-digestible, feruloylated oligo- and polysaccharides (FOPS) from maize bran and wheat bran, and determined the fermentation properties of partially purified FOPS from …

Nsf Grant Helps Preserve Parasite Collections [Press Release], Scott Gardner, Leslie Reed

Scott L. Gardner Publications

The National Science Foundation has awarded a $500,000 grant that will allow four major parasite collections to be digitized. The collections are part of UNL's Harold W. Manter Laboratory of Parasitology. Scott Gardner (pictured) is the curator and director of the Manter Laboratory.

A $500,000 grant from the National Science Foundation will allow the Harold W. Manter Laboratory of Parasitology to digitally preserve four major collections of parasite specimens donated to the University of Nebraska-Lincoln during the past five years.

Interspecific Egg Rejection As Ecological Collateral Damage From Selection Driven By Conspecific Brood Parasitism, Bruce E. Lyon, Daizaburo Shizuka, John M. Eadie

School of Biological Sciences: Faculty Publications

Distinguishing between interspecific and intraspecific coevolution as the selective driver of traits can be difficult in some taxa. A previous study of an avian obligate brood parasite, the black-headed duck, Heteronetta atricapilla, suggested that egg rejection by its two main hosts (two species of coot) is an incidental by-product of selection from conspecific brood parasitism within the hosts, not selection imposed by the interspecific parasite. However, although both species of coot can recognize and reject eggs of conspecific brood parasites, which closely resemble their own, they paradoxically also accept a moderate fraction of duck eggs (40–60%), which differ strikingly …

Composite Random Search Strategies Based On Non-Directional Sensory Cues, Ben C. Nolting, Travis M. Hinkelman, Chad Brassil, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

Many foraging animals find food using composite random search strategies, which consist of intensive and extensive search modes. Models of composite search can generate predictions about how optimal foragers should behave in each search mode, and how they should determine when to switch between search modes. Most of these models assume that foragers use resource encounters to decide when to switch between search modes. Empirical observations indicate that a variety of organisms use nondirectional sensory cues to identify areas that warrant intensive search. These cues are not precise enough to allow a forager to directly orient itself to a resource, …

The Molecular Biology Capstone Assessment: A Concept Assessment For Upper-Division Molecular Biology Students, Brian A. Couch, William B. Wood, Jennifer K. Knight

School of Biological Sciences: Faculty Publications

Measuring students’ conceptual understandings has become increasingly important to biology faculty members involved in evaluating and improving departmental programs. We developed the Molecular Biology Capstone Assessment (MBCA) to gauge comprehension of fundamental concepts in molecular and cell biology and the ability to apply these concepts in novel scenarios. Targeted at graduating students, the MBCA consists of 18 multiple-true/false (T/F) questions. Each question consists of a narrative stem followed by four T/F statements, which allows a more detailed assessment of student understanding than the traditional multiple-choice format. Questions were iteratively developed with extensive faculty and student feedback, including validation through faculty …

Scientific Teaching: Defining A Taxonomy Of Observable Practices, Brian Couch, Tanya L. Brown, Tyler J. Schelpat, Mark J. Graham, Jennifer K. Knight

School of Biological Sciences: Faculty Publications

Over the past several decades, numerous reports have been published advocating for changes to undergraduate science education. These national calls inspired the formation of the National Academies Summer Institutes on Undergraduate Education in Biology (SI), a group of regional workshops to help faculty members learn and implement interactive teaching methods. The SI curriculum promotes a pedagogical framework called Scientific Teaching (ST), which aims to bring the vitality of modern research into the classroom by engaging students in the scientific discovery process and using student data to inform the ongoing development of teaching methods. With the spread of ST, the need …

Temporal Patterns Of Nutrition Dependence In Secondary Sexual Traits And Their Varying Impacts On Male Mating Success, Malcolm F. Rosenthal, Eileen A. Hebets

Eileen Hebets Publications

Variation in the quantity of nutrients ingested over an individual’s lifetime is likely to differentially affect distinct male secondary sexual traits and courtship signals, potentially providing females with information about a male’s past and present foraging history. We hypothesize that female choice is thus influenced by a male’s lifetime foraging history. To test this, we manipulated the quantity of nutrients (i.e. prey items) available to male wolf spiders, Schizocosa stridulans, using a fully crossed 2 × 2 design with low versus high prey quantity across juvenile and adult life stages, and assessed the impact of these diet treatments on male …

Observational Learning In The Jumping Spider Phidippus Audax, Robert M. Adams

School of Biological Sciences: Dissertations, Theses, and Student Research

Observational learning is a complex form of learning most frequently studied in social vertebrates. However, evidence for social learning exists in several invertebrate species Evidence of invertebrate observational learning also exists, though to a lesser extent. This study addresses observational learning in a jumping spider (Phidippus audax) through video playback. My results suggest that while observational learning is occurring, the exact mechanism in use remains unclear. Spiders that saw a conspecific satiate itself on a prey item readily attacked a similar prey item when exposed to a live prey item. However, spiders exposed to a conspecific rejecting or …

The Body Size Dependence Of Trophic Cascades, John Delong, Benjamin Gilbert, Jonathan B. Shurin, Van M. Savage, Brandon T. Barton, Christopher F. Clements, Anthony I. Dell, Hamish S. Greig, Christopher D.G. Harley, Pavel Kratina, Kevin S. Mccann, Tyler D. Tunney, David A. Vasseur, Mary I. O’Connor

School of Biological Sciences: Faculty Publications

Trophic cascades are indirect positive effects of predators on resources via control of intermediate consumers. Larger-bodied predators appear to induce stronger trophic cascades (a greater rebound of resource density toward carrying capacity), but how this happens is unknown because we lack a clear depiction of how the strength of trophic cascades is determined. Using consumer-resource models, we first show that the strength of a trophic cascade has an upper limit set by the interaction strength between the basal trophic group and its consumer and that this limit is approached as the interaction strength between the consumer and its predator increases. …

Phylogenetic And Fossil Evidence For A Common Body Size Attractor In Marine Mammals, William Gearty, Jonathan Payne

School of Biological Sciences: Posters and Presentations

Evolutionary transitions between terrestrial and aquatic habitats are rare and often have large effects on the evolutionary trajectory of the clade making the transition. Following a single transition from the marine realm to the terrestrial realm, tetrapods have subsequently re-evolved a marine lifestyle at least 30 separate times. At least six of these re-invasions of the water occurred within crown-group mammals and four [sirenians (Sirenia), whales (Cetacea), pinnipeds (Pinnipedia), and otters (Lutrinae)] clades are extant. Although marine mammals are widely known to be larger than their terrestrial sister groups, the extent to which the body size evolution of these clades …

Octopamine Levels Relate To Male Mating Tactic Expression In The Wolf Spider Rabidosa Punctulata, Eileen A. Hebets, Matthew Hansen, Thomas C. Jones, Dustin J. Wilgers

Eileen Hebets Publications

In the wolf spider Rabidosa punctulata, upon encountering a female, males use one of two distinct strategies: (1) they court the female in an attempt to elicit a mating, or (2) they engage in a direct-mount tactic that involves extensive grappling with the female until a mating is achieved. The latter tactic appears more sexually aggressive, and both tactics come with the risk of being cannibalized. We explored the physiological mechanisms underlying this behavioral variation by assessing the relationship between circulating levels of the biogenic amine octopamine (OA), a neuromodulator suggested to play a role in “fight or flight” responses …

Pollen Limitation And Flower Abortion In A Wind-Pollinated, Masting Tree, Ian S. Pearse, Walter D. Koenig, Kyle A. Funk, Mario B. Pesendorfer

School of Biological Sciences: Faculty Publications

Pollen limitation is a key assumption of theories that explain mast seeding, which is common among wind-pollinated and woody plants. In particular, the pollen coupling hypothesis and pollination Moran effect hypothesis assume pollen limitation as a factor that synchronizes seed crops across individuals. The existence of pollen limitation has not, however, been unambiguously demonstrated in wind-pollinated, masting trees. We conducted a two-year pollen supplementation experiment on a masting oak species, Quercus lobata. Supplemental pollen increased acorn set in one year but not in the other, supporting the importance of pollen coupling and pollination Moran effect models of mast seeding. …

Convergent Evolution Of Hemoglobin Function In High-Altitude Andean Waterfowl Involves Limited Parallelism At The Molecular Sequence Level, Chandrasekhar Natarajan, Joana Projecto-Garcia, Hideaki Moriyama, Roy E. Weber, Violeta Muñoz-Fuentes, Andy J. Green, Cecilia Kopuchian, Pablo L. Tubaro, Luis Alza, Mariana Bulgarella, Matthew M. Smith, Robert E. Wilson, Angela Fago, Kevin G. Mccracken, Jay F. Storz

School of Biological Sciences: Faculty Publications

A fundamental question in evolutionary genetics concerns the extent to which adaptive phenotypic convergence is attributable to convergent or parallel changes at the molecular sequence level. Here we report a comparative analysis of hemoglobin (Hb) function in eight phylogenetically replicated pairs of high- and low-altitude waterfowl taxa to test for convergence in the oxygenation properties of Hb, and to assess the extent to which convergence in biochemical phenotype is attributable to repeated amino acid replacements. Functional experiments on native Hb variants and protein engineering experiments based on sitedirected mutagenesis revealed the phenotypic effects of specific amino acid replacements that were …

Evolution In Action: Climate Change, Biodiversity Dynamics And Emerging Infectious Disease, Eric P. Hoberg, Daniel R. Brooks

Harold W. Manter Laboratory of Parasitology: Faculty and Staff Publications

Climatological variation and ecological perturbation have been pervasive drivers of faunal assembly, structure and diversification for parasites and pathogens through recurrent events of geographical and host colonization at varying spatial and temporal scales of Earth history. Episodic shifts in climate and environmental settings, in conjunction with ecological mechanisms and host switching, are often critical determinants of parasite diversification, a view counter to more than a century of coevolutionary thinking about the nature of complex host–parasite assemblages. Parasites are resource specialists with restricted host ranges, yet shifts onto relatively unrelated hosts are common during phylogenetic diversification of parasite lineages and directly …

Transgenic Virus Resistance In Crop-Wild Cucurbita Pepo Does Not Prevent Vertical Transmission Of Zucchini Yellow Mosaic Virus, H. E. Simmons, H. R. Prendeville, J. P. Dunham, M. J. Ferrari, J. D. Earnest, Diana Pilson, G. P. Munkvold, E. C. Holmes, A. G. Stephenson

School of Biological Sciences: Faculty Publications

Zucchini yellow mosaic virus (ZYMV) is an economically important pathogen of cucurbits that is transmitted both horizontally and vertically. Although ZYMV is seed-transmitted in Cucurbita pepo, the potential for seed transmission in virus-resistant transgenic cultivars is not known. We crossed and backcrossed a transgenic squash cultivar with wild C. pepo, and determined whether seed-to-seedling transmission of ZYMV was possible in seeds harvested from transgenic backcrossed C. pepo.We then compared these transmission rates to those of non-transgenic (backcrossed and wild) C. pepo. The overall seed-to-seedling transmission rate in ZYMV was similar to those found in previous studies …

Plant Species’ Origin Predicts Dominance And Response To Nutrient Enrichment And Herbivores In Global Grasslands, Eric W. Seabloom, Elizabeth T. Borer, Yvonne Buckley, Elsa E. Cleland, Kendi F. Davies, Jennifer Firn, W. Stanley Harpole, Yann Hautier, Eric M. Lind, Andrew Macdougall, John L. Orrock, Suzanne M. Prober, Peter B. Adler, T. Michael Anderson, Jonathan D. Bakker, Lori A. Biederman, Dana M. Blumenthal, Cynthia S. Brown, Lars A. Brudvig, Marc W. Cadotte, Chengjin Chu, Kathryn L. Cottingham, Michael J. Crawley, Ellen I. Damschen, Carla M. Dantonio, Nicole M. Decrappeo, Guozhen Du, Philip A. Fay, Paul Frater, Daniel S. Gruner, Nicole Hagenah, Andy Hector, Helmut Hillebrand, Kirsten S. Hofmockel, Hope Humphries, Virginia L. Jin, Adam Kay, Kevin P. Kirkman, Julia A. Klein, Johannes M. H. Knops, Kimberly J. La Pierre, Laura M. Ladwig, John G. Lambrinos, Qi Li, Wei Li, Robin Marushia, Rebecca Mcculley, Brett Melbourne, Charles E. Mitchell, Joslin L. Moore, John Morgan, Brent Mortensen, Lydia R. O'Halloran, David A. Pyke, Anita C. Risch, Mahesh Sankaran, Martin Schuetz, Anna Simonsen, Melinda D. Smith, Carly J. Stevens, Lauren L. Sullivan, Elizabeth M. Wolkovich, Peter D. Wragg, Justin Wright, Louie Yang

School of Biological Sciences: Faculty Publications

Exotic species dominate many communities; however the functional significance of species’ biogeographic origin remains highly contentious. This debate is fuelled in part by the lack of globally replicated, systematic data assessing the relationship between species provenance, function and response to perturbations. We examined the abundance of native and exotic plant species at 64 grasslands in 13 countries, and at a subset of the sites we experimentally tested native and exotic species responses to two fundamental drivers of invasion, mineral nutrient supplies and vertebrate herbivory. Exotic species are six times more likely to dominate communities than native species. Furthermore, while experimental …

Analysis Of A Coupled N-Patch Population Model With Ceiling Density Dependence, Jason Callahan, Richard Rebarber, Eva Strawbridge, Brigitte Tenhumberg, Shenglan Yuan

School of Biological Sciences: Faculty Publications

We consider a system of difference equations with ceiling density dependence to model the dynamics of a coupled population on an arbitrary, finite number of distinct patches where migration between all patches is possible. In this model, each patch possesses a separate carrying capacity, and the dynamics of the coupled population is governed by a linear model until the population of a patch reaches its capacity, after which it remains at this maximum value. Further, we analyze the global attractors of this model and apply these results to an Arabian oryx metapopulation model with some patches protected and others unprotected …

The Complexities Of Female Mate Choice And Male Polymorphisms: Elucidating The Role Of Genetics, Age, And Mate-Choice Copying, Kasey D. Fowler-Finn, Laura Sullivan-Beckers, Amy M. Runck, Eileen A. Hebets

Eileen Hebets Publications

Genetic, life history, and environmental factors dictate patterns of variation in sexual traits within and across populations, and thus the action and outcome of sexual selection. This study explores patterns of inheritance, diet, age, and mate-choice copying on the expression of male sexual signals and associated female mate choice in a phenotypically diverse group of Schizocosa wolf spiders. Focal spiders exhibit one of two male phenotypes: ‘ornamented’ males possess large black brushes on their forelegs, and ‘non-ornamented’ males possess no brushes. Using a quantitative genetics breeding design in a mixed population of ornamented/non-ornamented males, we found a strong genetic basis …

Functional Approach To Condition, Dustin J. Wilgers, Eileen A. Hebets

Eileen Hebets Publications

Animal signaling is commonly thought to be costly. Signaling costs can arise via a variety of avenues, including energy expenditure, predator attraction, and so on (reviews in Zuk and Kolluru, 1998; Kotiaho, 2001), and are predicted to increase with signal expression (e.g., size, amplitude, and intensity; Johnstone, 1997). Due to these costs, signaler condition, which is hypothesized to be a reflection of a signaler’s genetic quality, is expected to influence the level of signal expression one can afford (Zahavi, 1975), resulting in a positive correlation between signaler condition and signal expression – that is, condition-dependent signaling (Zahavi, 1977; West-Eberhard, 1979; …

Site-Specific Differences In T Cell Frequencies And Phenotypes In The Blood And Gut Of Hivuninfected And Art-Treated Hiv+ Adults, Steven A. Yukl, Amandeep K. Shergill, Valerie Girling, Qingsheng Li, Maudi Killian, Lorrie Epling, Peilin Li, Philipp Kaiser, Ashley Haase, Diane V. Havlir, Kenneth Mcquaid, Elizabeth Sinclair, Joseph K. Wong

School of Biological Sciences: Faculty Publications

Gastrointestinal T lymphocytes are critical for mucosal immunity and HIV pathogenesis, yet little is known about normal T cell numbers and phenotypes in different regions of the gut, or the degree to which ART can restore levels to those of HIV-uninfected individuals. To investigate these questions, we measured T cell frequencies and markers of memory, activation, anergy, and homing in the blood, ileum, and rectum of HIV- and ART-suppressed HIV+ adults. In HIV- individuals, T cell frequencies and phenotypes differed significantly between sites. Compared to HIV- adults, HIV+ adults had lower absolute CD4+T cell counts in the ileal lamina propria …

What Drives Masting? The Phenological Synchrony Hypothesis, Walter D. Koenig, Johannes M.H. Knops, William J. Carmen, Ian S. Pearse

School of Biological Sciences: Faculty Publications

Annually variable and synchronous seed production, or masting behavior, is a widespread phenomenon with dramatic effects on wildlife populations and their associated communities. Proximally, masting is often correlated with environmental factors and most likely involves differential pollination success and resource allocation, but little is known about how these factors interact or how they influence seed production. We studied masting in the valley oak (Quercus lobata Nee), a California endemic tree, and report evidence that phenological synchrony in flowering driven by microclimatic variability determines the size of the acorn crop through its effects on pollen availability and fertilization success. These …