Biology Commons^™

How Fast Is Fast? Eco-Evolutionary Dynamics And Rates Of Change In Populations And Phenotypes, John Delong, Valery E. Forbes, Nika Galic, Jean P. Gibert, Robert G. Laport, Joseph S. Phillips, Janna M. Vavra

School of Biological Sciences: Faculty Publications

It is increasingly recognized that evolution may occur in ecological time. It is not clear, however, how fast evolution – or phenotypic change more generally – may be in comparison with the associated ecology, or whether systems with fast ecological dynamics generally have relatively fast rates of phenotypic change. We developed a new dataset on standardized rates of change in population size and phenotypic traits for a wide range of species and taxonomic groups. We show that rates of change in phenotypes are generally no more than 2/3, and on average about 1/4, the concurrent rates of change in population …

Females Sample More Males At High Nesting Densities, But Ultimately Obtain Less Attractive Mates, Robin M. Tinghitella, Chelsea Stehle, Janette W. Boughman

School of Biological Sciences: Faculty Publications

Background: Sexual selection is largely driven by the availability of mates. Theory predicts that male competition and female choice should be density-dependent, with males competing more intensely at relatively high density, and females becoming increasingly discriminating when there are more males from whom to choose. Evidence for flexible mating decisions is growing, but we do not understand how environmental variation is incorporated into mate sampling strategies. We mimicked threespine stickleback (Gasterosteus aculeatus) breeding conditions in pools with high and low densities of nesting males and allowed females to search for mates to determine whether 1) mate search strategies change with …

Epistasis Constrains Mutational Pathways Of Hemoglobin Adaptation In High-Altitude Pikas, Danielle M. Tufts, Chandrasekhar Natarajan, Inge G. Revsbech, Joana Projecto- Garcia, Federico G. Hoffmann, Roy E. Weber, Angela Fago, Hideaki Moriyama, Jay F. Storz

School of Biological Sciences: Faculty Publications

A fundamental question in evolutionary genetics concerns the roles of mutational pleiotropy and epistasis in shaping trajectories of protein evolution. This question can be addressed most directly by using site-directed mutagenesis to explore the mutational landscape of protein function in experimentally defined regions of sequence space. Here, we evaluate how pleiotropic trade-offs and epistatic interactions influence the accessibility of alternative mutational pathways during the adaptive evolution of hemoglobin (Hb) function in high-altitude pikas (Mammalia: Lagomorpha). By combining ancestral protein resurrection with a combinatorial protein-engineering approach, we examined the functional effects of sequential mutational steps in all possible pathways that produced …

Contribution Of A Mutational Hot Spot To Hemoglobin Adaptation In High-Altitude Andean House Wrens, Spencer C. Galen, Chandrasekhar Natarajan, Hideaki Moriyama, Roy E. Weber, Angela Fago, Phred M. Benham, Andrea N. Chavez, Zachary A. Cheviron, Jay F. Storz, Christopher C. Witt

School of Biological Sciences: Faculty Publications

A key question in evolutionary genetics is why certain mutations or certain types of mutation make disproportionate contributions to adaptive phenotypic evolution. In principle, the preferential fixation of particular mutations could stem directly from variation in the underlying rate of mutation to function-altering alleles. However, the influence of mutation bias on the genetic architecture of phenotypic evolution is difficult to evaluate because data on rates of mutation to function-altering alleles are seldom available. Here, we report the discovery that a single point mutation at a highly mutable site in the βA-globin gene has contributed to an evolutionary change in hemoglobin …

Complete Genome Sequence Of Sulfolobus Solfataricus Strain 98/2 And Evolved Derivatives, Samuel Mccarthy, Julien Gradnigo, Tyler Johnson, Sophie Payne, Anna Lipzen, Joel Martin, Wendy Schackwitz, Etsuko Morlyama, Paul H. Blum

School of Biological Sciences: Faculty Publications

Sulfolobus solfataricus strain 98/2 is a thermoacidophilic chemoheterotrophic crenarcheote that grows optimally at 80°C and pH3.0 (1). The S. solfataricus 98/2 genome reported in 2009 (Gen- Bank accession no. CP001800.1, RefSeq NC_017274.1, GI: 261600703) is a deletion derivative of strain 98/2 called PBL2025 (2). It is often misconstrued as the wild-type strain 98/2, yet lacks a 50-kb region encoding numerous genes involved in sugar metabolism. A new closed and complete genome sequence for wildtype strain 98/2 referred to as SULA is presented here as GenBank accession no. CP011057 using locus tag SULA. This strain has been deposited at the Japan …

Complete Genome Sequence Of An Evolved Thermotoga Maritima Isolate, Raghuveer Singh, Julien Gradnigo, Derrick White, Anna Lipzen, Joel Martin, Wendy Schackwitz, Estuko N. Moriyama, Paul H. Blum

School of Biological Sciences: Faculty Publications

Thermotoga maritima MSB8 genomovar DSM3109 is a hyperthermophilic

anaerobic bacterium (1) that grows at 80°C, producing

a maximum of 4 mol of H2 per mol of glucose (2). There

are a variety of duplicated genes and direct repeats in its genome,

suggesting the potential for genome instability. Genome resequencing

of T. maritima MSB8 genomovar DSM3109 in 2011 and

2013 (3, 4) indicated that the earlier sequenced T. maritima MSB8

reported by Nelson et al. (NC_000853.1) (5) was an evolved laboratory

variant with an approximately 8-kb deletion located between

TM1847 and TM1848 (annotation according to reference

5). The 8-kb deletion may …

First Record On Secondary Pollen Presentation In The Cucurbitaceae Family, Shivani Jadeja

School of Biological Sciences: Faculty Publications

Aim – Secondary pollen presentation in flowers has been described only in a few species across about 25 plant families. The first report of secondary pollen presentation in the Cucurbitaceae family is given here.

Key result – Sechium talamancensis, endemic to high elevations in Costa Rica, presents nearly 39% of its pollen secondarily on the distal ends of its petals. The remaining pollen is presented on the anthers, the primary pollen presenters.

Significance – Closely related and commercially important congeners of S. talamancensis do not show secondary pollen presentation. Potential selective advantages of the phenomenon that differentiates S. talamancensis …

Membrane Association And Catabolite Repression Of The Sulfolobus Solfataricus Α-Amylase, Edith Soo, Deepak Rudrappa, Paul H. Blum

School of Biological Sciences: Faculty Publications

Sulfolobus solfataricus is a thermoacidophilic member of the archaea whose envelope consists of an ether-linked lipid monolayer surrounded by a protein S-layer. Protein translocation across this envelope must accommodate a steep proton gradient that is subject to temperature extremes. To better understand this process in vivo, studies were conducted on the S. solfataricus glycosyl hydrolyase family 57 α-Amylase (AmyA). Cell lines harboring site specific modifications of the amyA promoter and AmyA structural domains were created by gene replacement using markerless exchange and characterized by Western blot, enzyme assay and culture-based analysis. Fusion of amyA to the malAp promoter overcame amyAp …

Intraspecific Polymorphism, Interspecific Divergence, And The Origins Of Function-Altering Mutations In Deer Mouse Hemoglobin, Chandrasekhar Natarajan, Federico G. Hoffmann, Hayley C. Lanier, Cole J. Wolf, Zachary A. Cheviron, Matthew L. Spangler, Roy E. Weber, Angela Fago, Jay F. Storz

School of Biological Sciences: Faculty Publications

Major challenges for illuminating the genetic basis of phenotypic evolution are to identify causative mutations, to quantify their functional effects, to trace their origins as new or preexisting variants, and to assess the manner in which segregating variation is transduced into species differences. Here, we report an experimental analysis of genetic variation in hemoglobin (Hb) function within and among species of Peromyscus mice that are native to different elevations. A multilocus survey of sequence variation in the duplicated HBA and HBB genes in Peromyscus maniculatus revealed that function-altering amino acid variants are widely shared among geographically disparate populations

from different …

Gene Turnover In The Avian Globin Gene Families And Evolutionary Changes In Hemoglobin Isoform Expression, Juan C. Opazo, Federico G. Hoffmann, Chandrasekhar Natarajan, Christopher C. Witt, Michael Berenbrink, Jay F. Storz

School of Biological Sciences: Faculty Publications

The apparent stasis in the evolution of avian chromosomes suggests that birds may have experienced relatively low rates of gene gain and loss in multigene families. To investigate this possibility and to explore the phenotypic consequences of variation in gene copy number, we examined evolutionary changes in the families of genes that encode the α- and β-type subunits of hemoglobin (Hb), the tetrameric α₂β₂ protein responsible for blood-O₂ transport. A comparative genomic analysis of 52 bird species revealed that the size and membership composition of the α- and β-globin gene families have remained remarkably constant during …

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 …

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 …

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; …

Extreme Features Of The Galdieria Sulphuraria Organellar Genomes: A Consequence Of Polyextremophily?, Kanika Jain, Kirsten Krause, Felix Grewe, Gaven F. Nelson, Andreas P. M. Weber, Alan C. Christensen, Jeffrey P. Mower

School of Biological Sciences: Faculty Publications

Nuclear genome sequencing from extremophilic eukaryotes has revealed clues about the mechanisms of adaptation to extreme environments, but the functional consequences of extremophily on organellar genomes are unknown. To address this issue, we assembled the mitochondrial and plastid genomes from a polyextremophilic red alga, Galdieria sulphuraria strain 074W, and performed a comparative genomic analysis with other red algae andmore broadly across eukaryotes. The mitogenomeis highly reduced in size and genetic content and exhibits the highest guanine–cytosine skew of any known genome and the fastest substitution rate among all red algae. The plastid genomecontains a large number of intergenic stem-loop structures …

Genome-Wide Gene Expression In Relation To Age In Large Laboratory Cohorts Of Drosophila Melanogaster, Kimberly A. Carlson, Kylee Gardner, Anjeza Pashaj, Darby J. Carlson, Fang Yu, James D. Eudy, Chi Zhang, Lawrence G. Harshman

School of Biological Sciences: Faculty Publications

Aging is a complex process characterized by a steady decline in an organism’s ability to perform life-sustaining tasks. In the present study, two cages of approximately 12,000 mated Drosophila melanogaster females were used as a source of RNA from individuals sampled frequently as a function of age. A linear model for micro array data method was used for the micro array analysis to adjust for the box effect; it identified 1,581 candidate aging genes.Cluster analyses using a self-organizing map algorithm on the 1,581 significant genes identified gene expression patterns across different ages. Genes involved in immune system function and regulation, …

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 …

Complete Genome Sequences Of Evolved Arsenate-Resistant Metallosphaera Sedula Strains, Chenbing Ai, Samuel Mccarthy, Wendy Schackwitz, Joel Martin, Anna Lipzen, Paul H. Blum

School of Biological Sciences: Faculty Publications

Metallosphaera sedula is a thermoacidophilic crenarchaeote with a 2.19-Mb genome. Here, we report the genome sequences of several evolved derivatives of M. sedula generated through adaptive laboratory evolution for enhanced arsenate resistance.

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 …

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. …

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 …

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 …

Assessing Pesticide Risks To Threatened And Endangered Species Using Population Models: Findings And Recommendations From A Croplife America Science Forum, V. E. Forbes, R. Brain, D. Edwards, N. Galic, T. Hall, J. Honegger, C. Meyer, D.R.J. Moore, D. Nacci, R. Pastorok, T. G. Preuss, S. F. Railsback, C. Salice, R. M. Sibly, B. Tenhumberg, P. Thorbek, M. Wang

School of Biological Sciences: Faculty Publications

This brief communication reports on the main findings and recommendations from the 2014 Science Forum organized by CropLife America. The aim of the forum was to gain a better understanding of the current status of population models and how they could be used in ecological risk assessments for threatened and endangered species potentially exposed to pesticides in the United States. The forum panelists' recommendations are intended to assist the relevant government agencies with implementation of population modeling in future endangered species risk assessments for pesticides. The forum included keynote presentations that provided an overview of current practices, highlighted the findings …

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 …

A Comparison Of Two Low-Stakes Methods For Administering A Program-Level Biology Concept Assessment, Brian A. Couch, Jennifer K. Knight

School of Biological Sciences: Faculty Publications

Concept assessments are used commonly in undergraduate science courses to assess student learning and diagnose areas of student difficulty. While most concept assessments align with the content of individual courses or course topics, some concept assessments have been developed for use at the programmatic level to gauge student progress and achievement over a series of courses or an entire major. The broad scope of a program-level assessment, which exceeds the content of any single course, creates several test administration issues, including finding a suitable time for students to take the assessment and adequately incentivizing student participation. These logistical considerations must …

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 …

Gillespie Eco-Evolutionary Models (Gems) Reveal The Role Of Heritable Trait Variation In Eco-Evolutionary Dynamics, John Delong, Jean P. Gibert

School of Biological Sciences: Faculty Publications

Heritable trait variation is a central and necessary ingredient of evolution. Trait variation also directly affects ecological processes, generating a clear link between evolutionary and ecological dynamics. Despite the changes in variation that occur through selection, drift, mutation, and recombination, current ecoevolutionary models usually fail to track how variation changes through time. Moreover, eco-evolutionary models assume fitness functions for each trait and each ecological context, which often do not have empirical validation. We introduce a new type of model, Gillespie eco-evolutionary models (GEMs), that resolves these concerns by tracking distributions of traits through time as ecoevolutionary dynamics progress. This is …

Nutritional Physiology Of Life-History Trade-Offs: How Food Protein–Carbohydrate Content Influences Life-History Traits In The Wing-Polymorphic Cricket Gryllus Firmus, Rebecca M. Clark, Anthony J. Zera, Spencer T. Behmer

School of Biological Sciences: Faculty Publications

Although life-history trade-offs result from the differential acquisition and allocation of nutritional resources to competing physiological functions, many aspects of this topic remain poorly understood. Wing-polymorphic insects, which possess alternative morphs that trade off allocation to flight capability versus early reproduction, provide a good model system for exploring this topic. In this study, we used the wing-polymorphic cricket Gryllus firmus to test how expression of the flight capability versus reproduction trade-off was modified across a heterogeneous protein–carbohydrate nutritional landscape. Newly molted adult female long- and short-winged crickets were given one of 13 diets with different concentrations and ratios of protein …

Globally, Functional Traits Are Weak Predictors Of Juvenile Tree Growth, And We Do Not Know Why, C. E. Timothy Paine, Lucy Amissah, Harald Auge, Christopher Baraloto, Martin Baruffol, Nils Bourland, Helge Bruelheide, Kasso Dainou, Roland C. De Gouvenain, Jean-Louis Doucet, Susan Doust, Paul V. A. Fine, Claire Fortunel, Josephine Haase, Karen D. Holl, Herve Jactel, Xuefei Li, Kaoru Kitajima, Julia Koricheva, Cristina Martinez-Garza, Christian Messier, Alain Paquette, Christopher Philipson, Daniel Piotto, Lourens Poorter, Juan M. Posada, Catherine Potvin, Kalle Rainio, Sabrina E. Russo, Mariacarmen Ruiz-Jaen, Michael Scherer-Lorenzen, Campbell O. Webb, S. Joseph Wright, Rakan A. Zahawi, Andy Hector

School of Biological Sciences: Faculty Publications

1. Plant functional traits, in particular specific leaf area (SLA), wood density and seed mass, are often good predictors of individual tree growth rates within communities. Individuals and species with high SLA, low wood density and small seeds tend to have faster growth rates. 2. If community-level relationships between traits and growth have general predictive value, then similar relationships should also be observed in analyses that integrate across taxa, biogeographic regions and environments. Such global consistency would imply that traits could serve as valuable proxies for the complex suite of factors that determine growth rate, and, therefore, could underpin a …

Evaluation Of Stem Rot In 339 Bornean Tree Species: Implications Of Size, Taxonomy, And Soil-Related Variation For Aboveground Biomass Estimates, K. D. Heineman, S. E. Russo, I. C. Baillie, J. D. Mamit, P. P.-K. Chai, L. Chai, E. W. Hindley, B.-T. Lau, S. Tan, P. S. Ashton

School of Biological Sciences: Faculty Publications

Fungal decay of heart wood creates hollows and areas of reduced wood density within the stems of living trees known as stem rot. Although stem rot is acknowledged as a source of error in forest aboveground biomass (AGB) estimates, there are few data sets available to evaluate the controls over stem rot infection and severity in tropical forests. Using legacy and recent data from 3180 drilled, felled, and cored stems in mixed dipterocarp forests in Sarawak, Malaysian Borneo, we quantified the frequency and severity of stem rot in a total of 339 tree species, and related variation in stem rot …

Transcriptional ‘Memory’ Of A Stress: Transient Chromatin And Memory (Epigenetic) Marks At Stress-Response Genes, Zoya Avramova

School of Biological Sciences: Faculty Publications

Drought, salinity, extreme temperature variations, pathogen and herbivory attacks are recurring environmental stresses experienced by plants throughout their life. To survive repeated stresses, plants provide responses that may be different from their response during the first encounter with the stress. A different response to a similar stress represents the concept of ‘stress memory’. A coordinated reaction at the organismal, cellular and gene/genome levels is thought to increase survival chances by improving the plant’s tolerance/ avoidance abilities. Ultimately, stress memory may provide a mechanism for acclimation and adaptation. At the molecular level, the concept of stress memory indicates that the mechanisms …