Biology Commons^™

Cd32 Is Expressed On Cells With Transcriptionally Active Hiv But Does Not Enrich For Hiv Dna In Resting T Cells, Mohamed Abdel-Mohsen, Leticia Kuri-Cervantes, Judith Grau-Exposito, Adam M. Spivak, Racheal A. Nell, Costin Tomescu, Surya Kumari Vadrevu, Leila B. Giron, Carla Serra-Peinado, Meritxell Genesca, Josep Castellvi, Guoxin Wu, Perla M. Del Rio Estrada, Mauricio Gonzalez-Navarro, Kenneth Lynn, Collin T. King, Sai Vemula, Kara Cox, Yanmin Wan, Qingsheng Li, Karam Mounzer, Jay Kostman, Ian Frank, Mirko Paiardini, Daria Hazuda, Gustavo Reyes-Teran, Douglas Richman, Bonnie Howell, Pablo Tebas, Javier Martinez-Picado, Vicente Planelles, Maria J. Buzon, Michael R. Betts, Luis J. Montaner

School of Biological Sciences: Faculty Publications

The persistence of HIV reservoirs, including latently infected, resting CD4⁺ T cells, is the major obstacle to cure HIV infection. CD32a expression was recently reported to mark CD4⁺ T cells harboring a replication-competent HIV reservoir during antiretroviral therapy (ART) suppression. We aimed to determine whether CD32 expression marks HIV latently or transcriptionally active infected CD4⁺ T cells. Using peripheral blood and lymphoid tissue of ART-treated HIV⁺ or SIV⁺ subjects, we found that most of the circulating memory CD32⁺ CD4⁺ T cells expressed markers of activation, including CD69, HLA-DR, CD25, CD38, and Ki67, and …

Temporal Variation In Predation Risk May Explain Daily Rhythms Of Foraging Behavior In An Orb-Weaving Spider, J. Colton Watts, Thomas C. Jones, Ashley Herrig, Madeleine Miller, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

Daily rhythms occur in numerous physiological and behavioral processes across an immense diversity of taxa, but there remain few cases in which mechanistic links between rhythms of trait expression and organismal fitness have been established. We construct a dynamic optimization model to determine whether risk allocation provides an adaptive explanation for the daily foraging rhythm observed in many species using the orb-weaving spider Cyclosa turbinata as a case study. Our model predicts that female C. turbinata should generally start foraging at lower levels of energy reserves (i.e., should be less bold) during midday when predators are most abundant. We also …

Presence Of Fruits Decreases Probability Of Retaining Flowers In A Sequentially Flowering Plant, Shivani Jadeja, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

Both intrinsic and extrinsic plant processes affect the fate of flowers along an inflorescence in sequentially flowering plants. We investigated whether the intrinsic process of competition for limited resource between fruits and flowers owing to resource preemption or sink strength of basal fruits, or architectural effects due to posi- tional differences in the probability of retaining flowers, explains a lower probability of retaining distal flowers inYucca glauca. Further, we investigated how the extrinsic process of seed herbivory interacts with the plant’s intrinsic processes of flower retention. We carried out a field experiment to compare flower retention among nine combi- nations …

A Rapid And Efficient Method For Enriching Mitochondrial Dna From Plants, Mackenzie M. Strehle, Emma Purfeerst, Alan C. Christensen

School of Biological Sciences: Faculty Publications

Current mitochondrial purification techniques are tedious and protracted due to their emphasis on recovering physiologically active mitochondria. However, for studies that are exclusively interested in isolating mitochondrial DNA (mtDNA) for applications such as PCR and sequencing, respiring mitochondria - and the complex procedures that stem from the need to retain their function - are unnecessary. Still, global DNA extraction methods have proven insufficient for mitochondrial DNA isolation because nuclear mitochondrial DNA segments (NUMTs) pose unique challenges to accurate mtDNA quantification and characterization. We present a rapid and simple extraction technique that maximizes recovery of mitochondrial DNA from plant cells, while …

Rna-Seq Of Kaposi's Sarcoma Reveals Alterations In Glucose And Lipid Metabolism, For Yue Tso, Andrew V. Kossenkov, Salum J. Lidenge, Owen Ngalamika, John R. Ngowi, Julius Mwaiselage, Jayamanna Wickramasinghe, Eun Hee Kwon, John T. West, Paul M. Lieberman, Charles Wood

School of Biological Sciences: Faculty Publications

Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent of Kaposi's sarcoma (KS). It is endemic in a number of sub-Saharan African countries with infection rate of >50%. The high prevalence of HIV-1 coupled with late presentation of advanced cancer staging make KS the leading cancer in the region with poor prognosis and high mortality. Disease markers and cellular functions associated with KS tumorigenesis remain ill-defined. Several studies have attempted to investigate changes of the gene profile with in vitro infection of monoculture models, which are not likely to reflect the cellular complexity of the in vivo lesion environment. Our approach …

Ecoevo-Maps: An Ecology And Evolution Assessment For Introductory Through Advanced Undergraduates, Mindi M. Summers, Brian A. Couch, Jennifer K. Knight, Sara E. Brownell, Alison J. Crowe, Katharine Semsar, Christian D. Wright, Michelle K. Smith

School of Biological Sciences: Faculty Publications

A new assessment tool, Ecology and Evolution–Measuring Achievement and Progression in Science or EcoEvo-MAPS, measures student thinking in ecology and evolution during an undergraduate course of study. EcoEvo-MAPS targets foundational concepts in ecology and evolution and uses a novel approach that asks students to evaluate a series of predictions, conclusions, or interpretations as likely or unlikely to be true given a specific scenario. We collected evidence of validity and reliability for EcoEvo-MAPS through an iterative process of faculty review, student interviews, and analyses of assessment data from more than 3000 students at 34 associate’s-, bachelor’s-, master’s-, and doctoral-granting institutions. The …

Mitochondrial Dysfunction And Infection Generate Immunity–Fecundity Tradeoffs In Drosophila, Justin L. Buchanan, Colin D. Meiklejohn, Kristi L. Montooth

School of Biological Sciences: Faculty Publications

Physiological responses to short-term environmental stressors, such as infection, can have long-term consequences for fitness, particularly if the responses are inappropriate or nutrient resources are limited. Genetic variation affecting energy acquisition, storage, and usage can limit cellular energy availability and may influence resourceallocation tradeoffs even when environmental nutrients are plentiful. Here, we utilized Drosophila mitochondrial– nuclear genotypes to test whether disrupted mitochondrial function interferes with nutrient-sensing pathways, and whether this disruption has consequences for tradeoffs between immunity and fecundity. We found that an energetically-compromised genotype was relatively resistant to rapamycin—a drug that targets nutrient-sensing pathways and mimics resource limitation. Dietary …

Time-Lagged Effects Of Weather On Plant Demography: Drought And Astragalus Scaphoides, Brigitte Tenhumberg, Elizabeth E. Crone, Satu Ramula, Andrew J. Tyre

School of Biological Sciences: Faculty Publications

Temperature and precipitation determine the conditions where plant species can occur. Despite their significance, to date, surprisingly few demographic field studies have considered the effects of abiotic drivers. This is problematic because anticipating the effect of global climate change on plant population viability requires understanding how weather variables affect population dynamics. One possible reason for omitting the effect of weather variables in demographic studies is the difficulty in detecting tight associations between vital rates and environmental drivers. In this paper, we applied Functional Linear Models (FLMs) to long-term demographic data of the perennial wildflower, Astragalus scaphoides, and explored sensitivity of …

Synbiotics For Improved Human Health: Recent Developments, Challenges, And Opportunities, Janina A. Krumbeck, Jens Walter, Robert W. Hutkins

School of Biological Sciences: Faculty Publications

Research on combining pro- and prebiotics as synbiotics to enhance human and animal health has accelerated in the past 10 years, including many clinical trials that have assessed a diverse range of synbiotic formulations. In this review, we summarize these studies as well as the commercial applications of synbiotics that are available. In particular, we critically assess the claimed health benefits of synbiotic applications and the ecological and therapeutic factors to consider when designing synbiotics and discuss the implications of these concepts for future research in this field.

Molecular Basis Of Hemoglobin Adaptation In The High-Flying Bar-Headed Goose, Chandrasekhar Natarajan, Agnieszka Jendroszek, Amit Kumar, Roy E. Weber, Jeremy R. H. Tame, Angela Fago, Jay F. Storz

School of Biological Sciences: Faculty Publications

During the adaptive evolution of a particular trait, some selectively fixed mutations may be directly causative and others may be purely compensatory. The relative contribution of these two classes of mutation to adaptive phenotypic evolution depends on the form and prevalence of mutational pleiotropy. To investigate the nature of adaptive substitutions and their pleiotropic effects, we used a protein engineering approach to characterize the molecular basis of hemoglobin (Hb) adaptation in the high-flying bar-headed goose (Anser indicus), a hypoxia-tolerant species renowned for its trans-Himalayan migratory flights. To test the effects of observed substitutions on evolutionarily relevant genetic backgrounds, …

Change In Dominance Determines Herbivore Effects On Plant Biodiversity, Sally E. Koerner, Johannes Knops, Dustin J. Strong, 80 More Co-Authors

School of Biological Sciences: Faculty Publications

Herbivores alter plant biodiversity (species richness) in many of the world's ecosystems, but the magnitude and the direction of herbivore effects on biodiversity vary widely within and among ecosystems. One current theory predicts that herbivores enhance plant biodiversity at high productivity but have the opposite effect at low productivity. Yet, empirical support for the importance of site productivity as a mediator of these herbivore impacts is equivocal. Here, we synthesize data from 252 large-herbivore exclusion studies, spanning a 20-fold range in site productivity, to test an alternative hypothesis—that herbivore-induced changes in the competitive environment determine the response of plant biodiversity …

Reproductive Promiscuity In The Variegated Fairy-Wren: An Alternative Reproductive Strategy In The Absence Of Helpers?, Allison E. Johnson, Stephen Pruett-Jones

School of Biological Sciences: Faculty Publications

Cooperative breeding, in which auxiliary group members help rear related, but nondescendent young, is often explained by kin selection. Reproductive monogamy is predicted in cooperatively breeding systems, as monogamy increases intragroup relatedness and maximizes auxiliary inclusive fitness. While monogamy is observed across many systems, including eusocial insects and cooperatively breeding mammals, some cooperatively breeding birds exhibit high rates of extrapair paternity. Here we quantify paternity and examine the role of auxiliaries on extrapair paternity in the highly cooperative variegated fairy-wren, Malurus lamberti, a species with both male and female auxiliaries. Extrapair paternity occurred in 55.4% of nests, and 39.8% …

Vertebrate Body Size Jumps The Wright Way, Peter J. Wagner

School of Biological Sciences: Faculty Publications

Fossil data provide copious evidence that anatomical (morphological) change within individual lineages is not constant: short bursts of great change commonly separate long durations of little change (1, 2). Despite this, most models of morphological change assume that probabilities of morphological character change are the same from one generation to the next: even if rates change over time—such as in “Cambrian explosion” or “early burst” models, where high disparity among anatomies evolves early—then it is still assumed that fast rates of continuous character change gave way to slow rates of continuous change (3). In statistical parlance, early bursts usually are …

Nitrogen Addition And Ecosystem Functioning: Both Species Abundances And Traits Alter Community Structure And Function, Anna R. Tatarko, Johannes M.H. Knops

School of Biological Sciences: Faculty Publications

Increased nutrient inputs can cause shifts in plant community composition and plant functional traits, both of which affect ecosystem function. We studied community- and species-level leaf functional trait changes in a full factorial nitrogen (N), phosphorus (P), and potassium (K) fertilization experiment in a semi-arid grassland. Nitrogen was the only nutrient addition to significantly affect leaf functional traits, and N addition increased community-weighted specific leaf area (SLA) by 19%, leaf chlorophyll content by 34%, height by 26%, and leaf dry matter content (LDMC) decreased by 11% while leaf thickness and toughness did not change significantly. At the species level, most …

American Society Of Parasitologists Newsletter, Volume 39, Number 2, Fall/ Winter, 2017, Scott L. Gardner

American Society of Parasitologists: Newsletter

Fall/Winter 2017 issue of the ASP newsletter.

Small Rna-Dependent Gene Silencing In The Green Alga Chlamydomonas Reinhardtii: Functions And Mechanisms, Eun Jeong Kim

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

Small RNAs (sRNAs), ~20-30 nucleotides in length, are non-coding RNAs that play essential roles in the regulation of gene expression in eukaryotes. They lead to inactivation of cognate sequences at the post-transcriptional level via a variety of mechanisms involved in translation inhibition and/or RNA degradation.

In the Chlorophyta Chlamydomonas reinhardtii, however, the molecular machinery responsible for sRNA-mediated translational repression remains unclear. To address the mechanisms of translation inhibition by sRNA, we have isolated an RNAi defective mutant (Mut26), which contains a deletion of the gene encoding the homolog of CCR4 in Chlamydomonas. We investigated the expression …

Multiple Hypotheses Explain Variation In Extra-Pair Paternity At Different Levels In A Single Bird Family, Lyanne Brouwer, Martijn Van De Pol, Nataly Hidalgo Aranzamendi, Glen Bain, Daniel T. Baldassarre, Lesley C. Brooker, Michael G. Brooker, Diane Diane Colombelli-Négrel, Erik Enbody, Kurt Gielow, Michelle L. Hall, Allison E. Johnson, Jordan Karubian, Sjouke A. Kingma, Sonia Kleindorfer, Marina Louter, Raoul A. Mulder, Anne Peters, Stephen Pruett-Jones, Keith A. Tarvin, Derrick J. Thrasher, Claire W. Varian-Ramos, Michael S. Webster, Andrew Cockburn

School of Biological Sciences: Faculty Publications

Extra-pair paternity (EPP), where offspring are sired by a male other than the social male, varies enormously both within and among species. Trying to explain this variation has proved difficult because the majority of the interspecific variation is phylogenetically based. Ideally, variation in EPP should be investigated in closely related species, but clades with sufficient variation are rare. We present a comprehensive multifactorial test to explain variation in EPP among individuals in 20 populations of nine species over 89 years from a single bird family (Maluridae). Females had higher EPP in the presence of more helpers, more neighbors or …

The North American Quails, Partridges, And Pheasants, Paul A. Johnsgard

Zea E-Books Collection

This book documents the biology of six species of New World quails that are native to North America north of Mexico (mountain, scaled, Gambel’s, California, and Montezuma quails, and the northern bobwhite), three introduced Old World partridges (chukar, Himalayan snowcock, and gray partridge), and the introduced common (ring-necked) pheasant. Collectively, quails, partridges, and pheasants range throughout all of the continental United States and the Canadian provinces. Two of the species, the northern bobwhite and ring-necked pheasant, are the most economically important of all North American upland game birds. All of the species are hunted extensively for sport and are highly …

Phosphate Starvation Induces Replacement Of Phospholipids With The Betaine Lipid Diacylglycerol-N,N,N-Trimethylhomoserine In The Human Fungal Pathogen Candida Albicans, Surabhi Naik, Rebecca E. Cahoon, Bridget Tripp, Christian Elowsky, Sophie Alvarez, Kan Liu, Chi Zhang, Wayne R. Riekhof

School of Biological Sciences: Faculty Publications

We have previously demonstrated that phosphate starvation induces replacement of phosphatidylcholine with the betaine lipid diacylglyceryl-N,N,N-trimethylhomoserine (DGTS) in fungi. In Neurospora crassa, the BTA1 gene encodes the betaine lipid synthase, which is necessary and sufficient for DGTS synthesis. BTA1 expression and DGTS accumulation are part of the fungal phosphorus (P_i) deprivation (PHO) regulon, mediated by the NUC-1/Pho4p transcription factor. We now demonstrate that the human pathogen Candida albicans encodes a BTA1 ortholog (CaBTA1), which is activated during P_i scarcity. The CaBTA1 gene is also induced under certain biofilm-promoting conditions independent of P …

Field Evidence Challenges The Often-Presumed Relationship Between Early Male Maturation And Female-Biased Sexual Size Dimorphism, Marie Claire Chelini, Eileen Hebets

Eileen Hebets Publications

Female-biased sexual size dimorphism (SSD) is often considered an epiphenomenon of selection for the increased mating opportunities provided by early male maturation (i.e., protandry). Empirical evidence of the adaptive significance of protandry remains nonetheless fairly scarce. We use field data collected throughout the reproductive season of an SSD crab spider, Mecaphesa celer, to test two hypotheses: Protandry provides fitness benefits to males, leading to female-biased SSD, or protandry is an indirect consequence of selection for small male size/large female size. Using field-collected data, we modeled the probability of mating success for females and males according to their timing of …

Characterization Of A Novel Mitochondrial Plasmid In Brassica, Mackenzie Strehle

UCARE: Research Products

Possessing some of the largest and most complex genomes of any eukaryotic organelles, plant mitochondria are notorious for their rapidly rearranging genetic framework. In addition to containing a large and complex mitochondrial genome, the mitochondria of several plants in the genus Brassica have also been shown to contain an independent, self-replicating linear plasmid. Interestingly, the plasmid appears to be able to move independently between the cytoplasm and the mitochondria, and it can be paternally inherited, unlike the rest of the mitochondrial genome. The plasmid also has features similar to those of adenoviruses, including terminal inverted repeats and covalently bound proteins …

Multiple Streptomyces Species With Distinct Secondary Metabolomes Have Identical 16s Rrna Gene Sequences, Sanjay Antony-Babu, Didier Stien, Véronique Eparvier, Delphine Parrot, Sophie Tomasi, Marcelino Suzuki

School of Biological Sciences: Faculty Publications

Microbial diversity studies using small subunit (SSU) rRNA gene sequences continue to advance our understanding of biological and ecological systems. Although a good predictor of overall diversity, using this gene to infer the presence of a species in a sample is more controversial. Here, we present a detailed polyphasic analysis of 10 bacterial strains isolated from three coastal lichens Lichina confinis, Lichina pygmaea and Roccella fuciformis with SSU rRNA gene sequences identical to the type strain of Streptomyces cyaneofuscatus. This analysis included phenotypic, microscopic, genetic and genomic comparisons and showed that despite their identical SSU rRNA sequences the …

Assessing The Influence Of Temporal Autocorrelations On The Population Dynamics Of A Disturbance Specialist Plant Population In A Random Environment, Eric A. Eager, Diana Pilson, Helen M. Alexander, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

Biological populations are strongly influenced by random variations in their environment, which are often autocorrelated in time. For disturbance specialist plant populations, the frequency and intensity of environmental stochasticity (via disturbances) can drive the qualitative nature of their population dynamics. In this article, we extended our earlier model to explore the effect of temporally autocorrelated disturbances on population persistence. In our earlier work, we only assumed disturbances were independent and identically distributed in time. We proved that the plant seed bank population converges in distribution, and we showed that the mean and variance in seed bank population size were both …

Geographical Variation In Community Divergence: Insights From Tropical Forest Monodominance By Ectomycorrhizal Trees*, Tadashi Fukami, Mifuyu Nakajima, Claire Fortunel, Paul V. Fine, Christopher Baraloto, Sabrina E. Russo, Kabir G. Peay

School of Biological Sciences: Faculty Publications

Convergence occurs in both species traits and community structure, but how convergence at the two scales influences each other remains unclear. To address this question, we focus on tropical forest monodominance, in which a single, often ectomycorrhizal (EM) tree species occasionally dominates forest stands within a landscape otherwise characterized by diverse communities of arbuscular mycorrhizal (AM) trees. Such monodominance is a striking potential example of community divergence resulting in alternative stable states. However, it is observed only in some tropical regions. A diverse suite of AM and EM trees locally codominate forest stands elsewhere. We develop a hypothesis to explain …

Ectoparasitic Mites Of The Genus Gigantolaelaps (Acari: Mesostigmata: Laelapidae) Associated With Small Mammals Of The Genus Nephelomys (Rodentia: Sigmodontinae), Including Two New Species From Peru, Donald D. Gettinger, Scott Lyell Gardner

Scott L. Gardner Publications

An extensive survey of small mammals and ectoparasites along an altitudinal transect in the Manu Biodiversity Reserve in Peru found the sigmodontine rodent genus Nephelomys infested by mites of the genus Gigantolaelaps Fonseca, 1939. Two distinct species co-occurred exclusively in the pelage of Nephelomys keaysi, G. inca Fonseca and G. minima n. sp. Nephelomys levipes, which replaces N. keaysi at higher elevations, was infested exclusively with a single new species, G. nebulosa n. sp. In this paper, we formally describe these new mite species, and provide more information on the morphology of G. inca.

Abundance And Distribution Of Microbial Cells And Viruses In An Alluvial Aquifer, Donald Pan, Jason Nolan, Kenneth H. Williams, Karrie A. Weber

School of Biological Sciences: Faculty Publications

Viruses are the most abundant biological entity on Earth and their interactions with microbial communities are recognized to influence microbial ecology and impact biogeochemical cycling in various ecosystems. While the factors that control the distribution of viruses in surface aquatic environments are well-characterized, the abundance and distribution of continental subsurface viruses with respect to microbial abundance and biogeochemical parameters have not yet been established. In order to begin to understand the factors governing virus distribution in subsurface environments, we assessed microbial cell and virus abundance in groundwater concurrent with groundwater chemistry in a uranium impacted alluvial aquifer adjoining the Colorado …

How Question Types Reveal Student Thinking: An Experimental Comparison Of Multiple-True-False And Free-Response Formats, Joanna K. Hubbard, Macy A. Potts, Brian A. Couch

School of Biological Sciences: Faculty Publications

Assessments represent an important component of undergraduate courses because they affect how students interact with course content and gauge student achievement of course objectives. To make decisions on assessment design, instructors must understand the affordances and limitations of available question formats. Here, we use a crossover experimental design to identify differences in how multiple-true-false (MTF) and free-response (FR) exam questions reveal student thinking regarding specific conceptions. We report that correct response rates correlate across the two formats but that a higher percentage of students provide correct responses for MTF questions. We find that MTF questions reveal a high prevalence of …

Identification Of The Atpase Subunit Of The Primary Maltose Transporter In The Hyperthermophilic Anaerobe Thermotoga Maritima, Raghuveer Singh, Derrick White, Paul H. Blum

School of Biological Sciences: Faculty Publications

Thermotoga maritima is a hyperthermophilic anaerobic bacterium that produces molecular hydrogen (H₂) by fermentation. It catabolizes a broad range of carbohydrates through the action of diverse ABC transporters. However, in T. maritima and related species, highly similar genes with ambiguous annotation obscure a precise understanding of genome function. In T. maritima, three putative malK genes, all annotated as ATPase subunits, exhibited high identity to each other. To distinguish between these genes, malK disruption mutants were constructed by gene replacement, and the resulting mutant cell lines were characterized. Only a disruption of malK3 produced a defect in maltose …

Nitrogen Addition And Ecosystem Functioning: Changes In Species Composition Leaf Traits Amplify Increases In Leaf Area Index And Canopy Chlorophyll, Anna R. Tatarko

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

Increased nutrient inputs can cause shifts in plant community composition and plant functional traits, both of which affect ecosystem function. We studied community- and species-level changes in specific leaf area (SLA), chlorophyll, leaf thickness, leaf toughness, plant height and leaf dry matter content (LDMC) in a full factorial nitrogen (N), phosphorus (P), potassium (K) fertilization experiment in a semi-arid grassland. Nitrogen was the only nutrient addition to significantly affect leaf functional traits, and N addition increased community weighted SLA by 19%, leaf chlorophyll content by 34%, height by 26%, and resulted in an 11% decrease in LDMC while leaf thickness …

Nutrient Addition Shifts Plant Community Composition Towards Earlier Flowering Species In Some Prairie Ecoregions In The U.S. Central Plains, Lori A. Biederman, Brent Mortensen, Philip Fay, Nicole Hagenah, Johannes M. H. Knops, Kimberly J. La Pierre, Ramesh Laungani, Eric Lind, Rebecca Mcculley, Sally Power, Eric W. Seabloom, Pedro Tognetti

School of Biological Sciences: Faculty Publications

The distribution of flowering across the growing season is governed by each species' evolutionary history and climatic variability. However, global change factors, such as eutrophication and invasion, can alter plant community composition and thus change the distribution of flowering across the growing season. We examined three ecoregions (tall-, mixed, and short-grass prairie) across the U.S. Central Plains to determine how nutrient (nitrogen (N), phosphorus, and potassium (+micronutrient)) addition alters the temporal patterns of plant flowering traits. We calculated total community flowering potential (FP) by distributing peakseason plant cover values across the growing season, allocating each species' cover to only those …