1
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Quezada-Villa K, Cannizzo ZJ, Carver J, Dunn RP, Fletcher LS, Kimball ME, McMullin AL, Orocu B, Pfirrmann BW, Pinkston E, Reese TC, Smith N, Stancil C, Toscano BJ, Griffen BD. Predicting diet in brachyuran crabs using external morphology. PeerJ 2023; 11:e15224. [PMID: 37065690 PMCID: PMC10100828 DOI: 10.7717/peerj.15224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 03/22/2023] [Indexed: 04/18/2023] Open
Abstract
Morphological traits have often been used to predict diet and trophic position of species across many animal groups. Variation in gut size of closely related animals is known to be a good predictor of dietary habits. Species that are more herbivorous or that persist on low-quality diets often have larger stomachs than their carnivorous counterparts. This same pattern exists in crabs and in most species, individuals exhibit external markings on the dorsal side of their carapace that appear to align with the position and size of their gut. We hypothesized that these external markings could be used as an accurate estimate of the crab's cardiac stomach size, allowing an approximation of crab dietary strategies without the need to sacrifice and dissect individual animals. We used literature values for mean diet and standardized external gut size markings taken from crab photographs across 50 species to show that percent herbivory in the diet increases non-linearly across species of brachyuran crab with the external estimate of gut size. We also used data from dissections in four species to show that external gut markings were positively correlated with gut sizes, though the strength of this correlation differed across species. We conclude that when rough approximations of diet quality such as percent herbivory will suffice, measuring external carapace markings in crabs presents a quick, free, non-lethal alternative to dissections. Our results also provide important insights into tradeoffs that occur in crab morphology and have implications for crab evolution.
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Affiliation(s)
| | - Zachary J. Cannizzo
- National Oceanic and Atmospheric Administration Office of National Marine Sanctuaries—National Marine Protected Areas Center, Washington DC, United States
| | - Jade Carver
- Department of Biology, Brigham Young University, Provo, Utah, United States
| | - Robert P. Dunn
- Baruch Marine Field Laboratory, University of South Carolina, Georgetown, South Carolina, United States
- North Inlet-Winyah Bay National Estuarine Research Reserve, Georgetown, South Carolina, United States
| | - Laura S. Fletcher
- Department of Biology, Brigham Young University, Provo, Utah, United States
| | - Matthew E. Kimball
- Baruch Marine Field Laboratory, University of South Carolina, Georgetown, South Carolina, United States
| | | | - Brenden Orocu
- Department of Biology, Brigham Young University, Provo, Utah, United States
| | - Bruce W. Pfirrmann
- Baruch Marine Field Laboratory, University of South Carolina, Georgetown, South Carolina, United States
| | - Emily Pinkston
- Department of Biology, Brigham Young University, Provo, Utah, United States
| | - Tanner C. Reese
- Department of Biology, Brigham Young University, Provo, Utah, United States
| | - Nanette Smith
- Department of Biology, Brigham Young University, Provo, Utah, United States
| | - Carter Stancil
- Department of Biology, Brigham Young University, Provo, Utah, United States
| | - Benjamin J. Toscano
- Department of Biology, Trinity College, Hartford, Connecticut, United States
| | - Blaine D. Griffen
- Department of Biology, Brigham Young University, Provo, Utah, United States
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2
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Fuess LE, Weber JN, den Haan S, Steinel NC, Shim KC, Bolnick DI. Between-population differences in constitutive and infection-induced gene expression in threespine stickleback. Mol Ecol 2021; 30:6791-6805. [PMID: 34582586 PMCID: PMC8796319 DOI: 10.1111/mec.16197] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 09/16/2021] [Accepted: 09/22/2021] [Indexed: 02/06/2023]
Abstract
Vertebrate immunity is a complex system consisting of a mix of constitutive and inducible defences. Furthermore, host immunity is subject to selective pressure from a range of parasites and pathogens which can produce variation in these defences across populations. As populations evolve immune responses to parasites, they may adapt via a combination of (1) constitutive differences, (2) shared inducible responses, or (3) divergent inducible responses. Here, we leverage a powerful natural host‐parasite model system (Gasterosteus aculeatus and Schistochephalus solidus) to tease apart the relative contributions of these three types of adaptations to among‐population divergence in response to parasites. Gene expression analyses revealed limited evidence of significant divergence in constitutive expression of immune defence, and strong signatures of conserved inducible responses to the parasite. Furthermore, our results highlight a handful of immune‐related genes which show divergent inducible responses which may contribute disproportionately to functional differences in infection success or failure. In addition to investigating variation in evolutionary adaptation to parasite selection, we also leverage this unique data set to improve understanding of cellular mechanisms underlying a putative resistance phenotype (fibrosis). Combined, our results provide a case study in evolutionary immunology showing that a very small number of genes may contribute to genotype differences in infection response.
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Affiliation(s)
- Lauren E Fuess
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA.,Department of Biology, Texas State University, San Marcos, Texas, USA
| | - Jesse N Weber
- Department of Integrative Biology, University of Wisconsin - Madison, Madison, Wisconsin, USA
| | - Stijn den Haan
- International Institute for Industrial Environmental Economics (IIIEE), Lund University, Lund, Sweden
| | - Natalie C Steinel
- Department of Biological Sciences, University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Kum Chuan Shim
- Department of Ecology, Evolution, and Behavior, University of Texas at Austin, Austin, Texas, USA
| | - Daniel I Bolnick
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
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3
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Fleischer SR, Bolnick DI, Schreiber SJ. Sick of eating: Eco-evo-immuno dynamics of predators and their trophically acquired parasites. Evolution 2021; 75:2842-2856. [PMID: 34562317 PMCID: PMC8985590 DOI: 10.1111/evo.14353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 05/28/2021] [Indexed: 12/26/2022]
Abstract
When predators consume prey, they risk becoming infected with their prey's parasites, which can then establish the predator as a secondary host. A predator population's diet therefore influences what parasites it is exposed to, as has been repeatedly shown in many species such as threespine stickleback (Gasterosteus aculeatus) (more benthic‐feeding individuals obtain nematodes from oligocheate prey, whereas limnetic‐feeding individuals catch cestodes from copepod prey). These differing parasite encounters, in turn, determine how natural selection acts on the predator's immune system. We might therefore expect that ecoevolutionary dynamics of a predator's diet (as determined by its ecomorphology) should drive correlated evolution of its immune traits. Conversely, the predator's immunity to certain parasites might alter the relative costs and benefits of different prey, driving evolution of its ecomorphology. To evaluate the potential for ecological morphology to drive evolution of immunity, and vice versa, we use a quantitative genetics framework coupled with an ecological model of a predator and two prey species (the diet options). Our analysis reveals fundamental asymmetries in the evolution of ecomorphology and immunity. When ecomorphology rapidly evolves, it determines how immunity evolves, but not vice versa. Weak trade‐offs in ecological morphology select for diet generalists despite strong immunological trade‐offs, but not vice versa. Only weak immunological trade‐offs can explain negative diet‐infection correlations across populations. The analysis also reveals that eco‐evo‐immuno feedbacks destabilize population dynamics when trade‐offs are sufficiently weak and heritability is sufficiently high. Collectively, these results highlight the delicate interplay between multivariate trait evolution and the dynamics of ecological communities.
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Affiliation(s)
- Samuel R Fleischer
- Graduate Group in Applied Mathematics, University of California, Davis, Davis, California 95616
| | - Daniel I Bolnick
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut 06269
| | - Sebastian J Schreiber
- Department of Evolution and Ecology, University of California, Davis, Davis, California 95616
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4
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Li W, Zhai D, Wang C, Gao X, Liu H, Cao W. Relationships Among Trophic Niche Width, Morphological Variation, and Genetic Diversity of Hemiculter leucisculus in China. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.691218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
According to the niche variation hypothesis (NVH), the populations with wider niches are phenotypically more variable than those with narrow niches. Giller expanded the NVH, suggesting that the niche width, morphological variation, and genetic diversity are all positively correlated. However, the hypothesis has been a subject of debate and discussion. In the present study, the NVH was tested by analyzing the relationships among trophic niche width, morphological variation, and genetic diversity of Hemiculter leucisculus, a widespread cyprinid fish. The fish samples were collected from six sites across Haihe, the Yellow, and the Yangtze River basins in China. The relationships among trophic niche width, morphological variation, and genetic diversity were analyzed using Pearson correlation at the inter-population level. Our analysis indicated that trophic niche width is significantly positively correlated with morphological variation, which corroborates the NVH. Morphological variation was significantly correlated to genetic diversity. However, no relationship was observed between trophic niche width and genetic diversity. We inferred that the dietary niche of H. leucisculus might change due to the plastic response toward environmental changes rather than due to the genetic variation. We also suggest that the effects of environment and heredity on the niche of the freshwater fish should be quantified separately in further studies.
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5
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Costa A, Romano A, Rosa G, Salvidio S. Weighted individual-resource networks in prey-predator systems: the role of prey availability on the emergence of modular structures. Integr Zool 2021; 17:115-127. [PMID: 33415838 DOI: 10.1111/1749-4877.12520] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Ecological networks, usually depicting interactions among species, have been recently down-scaled to the individual level, permitting description of patterns of inter-individual resource variation that are usually hindered at the species level. Optimal diet theory (ODT) models, applied to prey-predator systems, predict different patterns of nestedness and modularity in the network, depending on the available resources and intra-specific competition. The effect of resource availability on the emergence of networks structures, and ODT framework, has not yet fully been clarified. Here, we analyzed the structural patterns of individual-resource networks in 3 species of Mediterranean salamanders, in relation to changes in prey availability. We used weighted individual-resource network metrics to interpret the observed patterns, according to 3 ODT models. We found significant nestedness recurring in our study system, indicating that both selective and opportunistic individuals occur in the same population. Prey diversity, rather than abundance, was apparently related to inter-individual resource variation and promoted the emergence of significant modularity within all networks. The observed patterns of nestedness and modularity, together with the variation in resource diversity and intra-specific competition, are in agreement with the distinct preferences model of ODT. These findings suggest that in the focal prey-predator systems, individuals were able to perceive changes in prey diversity and to exploit in different ways the variations in composition of available resources, shifting their diet assembly rules accordingly. Our findings also confirm that the use of weighted individual-resource networks, in prey-predator systems, allows to disclose dynamics that are masked at the species or population level.
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Affiliation(s)
- Andrea Costa
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genova, Genova, Italy
| | - Antonio Romano
- Italian National Research Council (CNR), Agriculture and Food Sciences Department (IBE), Institute of Bioeconomy - Biology, Roma, RM, Italy
| | - Giacomo Rosa
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genova, Genova, Italy
| | - Sebastiano Salvidio
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genova, Genova, Italy
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6
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Bolnick DI, Resetarits EJ, Ballare K, Stuart YE, Stutz WE. Scale-dependent effects of host patch traits on species composition in a stickleback parasite metacommunity. Ecology 2020; 101:e03181. [PMID: 32880940 PMCID: PMC7757261 DOI: 10.1002/ecy.3181] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 06/08/2020] [Accepted: 06/28/2020] [Indexed: 01/06/2023]
Abstract
A core goal of ecology is to understand the abiotic and biotic variables that regulate species distributions and community composition. A major obstacle is that the rules governing species distributions can change with spatial scale. Here, we illustrate this point using data from a spatially nested metacommunity of parasites infecting a metapopulation of threespine stickleback fish from 34 lakes on Vancouver Island, British Columbia. Like most parasite metacommunities, the composition of stickleback parasites differs among host individuals within each host population, and differs between host populations. The distribution of each parasite taxon depends, to varying degrees, on individual host traits (e.g., mass, diet) and on host-population characteristics (e.g., lake size, mean host mass, mean diet). However, in most cases in this data set, a given parasite was regulated by different factors at the host-individual and host-population scales, leading to scale-dependent patterns of parasite-species co-occurrence.
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Affiliation(s)
- Daniel I. Bolnick
- Department of Integrative BiologyUniversity of Texas at AustinAustinTexas78712USA
- Present address:
Ecology and Evolutionary Biology & Institute of System GenomicsUniversity of ConnecticutStorrsConnecticut06269USA
| | - Emlyn J. Resetarits
- Department of Integrative BiologyUniversity of Texas at AustinAustinTexas78712USA
- Present address:
Center for the Ecology of Infectious DiseaseOdum School of EcologyUniversity of GeorgiaAthensGeorgiaUSA
| | - Kimberly Ballare
- Department of Integrative BiologyUniversity of Texas at AustinAustinTexas78712USA
- Present address:
Ecology and Evolutionary BiologyUniversity of California Santa CruzSanta CruzCalifornia95064USA
| | - Yoel E. Stuart
- Department of Integrative BiologyUniversity of Texas at AustinAustinTexas78712USA
- Present address:
Department of BiologyLoyola UniversityChicagoIllinois60660USA
| | - William E. Stutz
- Department of Integrative BiologyUniversity of Texas at AustinAustinTexas78712USA
- Office of Institutional ResearchWestern Michigan UniversityKalamazooMichigan49008‐5253USA
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7
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Kerr NR, Ingram T. Personality does not predict individual niche variation in a freshwater fish. Behav Ecol 2020. [DOI: 10.1093/beheco/araa117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Animal populations can exhibit considerable interindividual variation in both behavioral traits and niche use, but the potential connections between these characteristics are rarely compared for the same individuals. We aimed to test whether behavioral syndromes were predictive of individual diet or microhabitat in a native New Zealand freshwater fish, Gobiomorphus cotidianus. We carried out laboratory behavioral assays and repeated habitat and diet measurements in a seminatural mesocosm system. We found considerable repeatability in individual behavior, largely consistent with a proactive/reactive behavioral syndrome. We also found modest individual repeatability in microhabitat use and relatively strong individual specialization in diet. However, no measure of niche use in the mesocosms was significantly predicted by individual personality. Further studies of this type will be needed to assess whether links between individual behavior and resource use are more important in other species or ecological contexts.
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Affiliation(s)
- Nicky R Kerr
- Department of Zoology, University of Otago, Dunedin, New Zealand
| | - Travis Ingram
- Department of Zoology, University of Otago, Dunedin, New Zealand
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8
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Balza U, Lois NA, Polito MJ, Pütz K, Salom A, Raya Rey A. The dynamic trophic niche of an island bird of prey. Ecol Evol 2020; 10:12264-12276. [PMID: 33209286 PMCID: PMC7663050 DOI: 10.1002/ece3.6856] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 08/27/2020] [Accepted: 09/02/2020] [Indexed: 11/08/2022] Open
Abstract
Optimal foraging theory predicts an inverse relationship between the availability of preferred prey and niche width in animals. Moreover, when individuals within a population have identical prey preferences and preferred prey is scarce, a nested pattern of trophic niche is expected if opportunistic and selective individuals can be identified. Here, we examined intraspecific variation in the trophic niche of a resident population of striated caracara (Phalcoboenus australis) on Isla de los Estados (Staten Island), Argentina, using pellet and stable isotope analyses. While this raptor specializes on seabird prey, we assessed this population's potential to forage on terrestrial prey, especially invasive herbivores as carrion, when seabirds are less accessible. We found that the isotopic niche of this species varies with season, age, breeding status, and, to a lesser extent, year. Our results were in general consistent with classic predictions of the optimal foraging theory, but we also explore other possible explanations for the observed pattern. Isotopic niche was broader for groups identified a priori as opportunistic (i.e., nonbreeding adults during the breeding season and the whole population during the nonbreeding season) than it was for individuals identified a priori as selective. Results suggested that terrestrial input was relatively low, and invasive mammals accounted for no more than 5% of the input. The seasonal pulse of rockhopper penguins likely interacts with caracara's reproductive status by constraining the spatial scale on which individuals forage. Niche expansion in spatially flexible individuals did not reflect an increase in terrestrial prey input; rather, it may be driven by a greater variation in the types of marine prey items consumed.
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Affiliation(s)
- Ulises Balza
- Laboratorio de Ecología y Conservación de Vida SilvestreCentro Austral de Investigaciones Científicas (CADIC‐CONICET)UshuaiaArgentina
- Departamento de Ecología, Genética y EvoluciónFacultad de Ciencias Exactas y NaturalesUniversidad de Buenos AiresBuenos AiresArgentina
| | - Nicolás A. Lois
- Departamento de Ecología, Genética y EvoluciónFacultad de Ciencias Exactas y NaturalesUniversidad de Buenos AiresBuenos AiresArgentina
- Instituto de Ecología Genética y Evolución de Buenos AiresCONICETBuenos AiresArgentina
| | - Michael J. Polito
- Department of Oceanography and Coastal SciencesLouisiana State UniversityBaton RougeLAUSA
| | | | - Amira Salom
- Laboratorio de Ecología y Conservación de Vida SilvestreCentro Austral de Investigaciones Científicas (CADIC‐CONICET)UshuaiaArgentina
- Departamento de Ecología, Genética y EvoluciónFacultad de Ciencias Exactas y NaturalesUniversidad de Buenos AiresBuenos AiresArgentina
| | - Andrea Raya Rey
- Laboratorio de Ecología y Conservación de Vida SilvestreCentro Austral de Investigaciones Científicas (CADIC‐CONICET)UshuaiaArgentina
- Instituto de Ciencias Polares, Ambiente y Recursos Naturales (ICPA)Universidad Nacional de Tierra del Fuego (UNTdF)UshuaiaArgentina
- Wildlife Conservation Society Representación ArgentinaBuenos AiresArgentina
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9
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Bolnick DI, Ballare KM. Resource diversity promotes among-individual diet variation, but not genomic diversity, in lake stickleback. Ecol Lett 2020; 23:495-505. [PMID: 31919988 PMCID: PMC7325224 DOI: 10.1111/ele.13448] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 08/07/2019] [Accepted: 11/24/2019] [Indexed: 12/11/2022]
Abstract
Many generalist species consist of specialised individuals that use different resources. This within-population niche variation can stabilise population and community dynamics. Consequently, ecologists wish to identify environmental settings that promote such variation. Theory predicts that environments with greater resource diversity favour ecological diversity among consumers (via disruptive selection or plasticity). Alternatively, niche variation might be a side-effect of neutral genomic diversity in larger populations. We tested these alternatives in a metapopulation of threespine stickleback. Stickleback consume benthic and limnetic invertebrates, focusing on the former in small lakes, the latter in large lakes. Intermediate-sized lakes support generalist stickleback populations using an even mixture of the two prey types, and exhibit greater among-individual variation in diet and morphology. In contrast, genomic diversity increases with lake size. Thus, phenotypic diversity and neutral genetic polymorphism are decoupled: trophic diversity being greatest in intermediate-sized lakes with high resource diversity, whereas neutral genetic diversity is greatest in the largest lakes.
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10
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Maciejewski MF, Jiang C, Stuart YE, Bolnick DI. Microhabitat contributes to microgeographic divergence in threespine stickleback. Evolution 2020; 74:749-763. [PMID: 32058582 DOI: 10.1111/evo.13942] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 01/22/2020] [Accepted: 01/27/2020] [Indexed: 12/20/2022]
Abstract
Since the New Synthesis, most migration-selection balance theory has predicted that there should be negligible differentiation over small spatial scales (relative to dispersal), because gene flow should erode any effect of divergent selection. Nevertheless, there are classic examples of microgeographic divergence, which theory suggests can arise under specific conditions: exceptionally strong selection, phenotypic plasticity in philopatric individuals, or nonrandom dispersal. Here, we present evidence of microgeographic morphological variation within lake and stream populations of threespine stickleback (Gasterosteus aculeatus). It seems reasonable to assume that a given lake or stream population of fish is well-mixed. However, we found this assumption to be untenable. We examined trap-to-trap variation in 34 morphological traits measured on stickleback from 16 lakes and 16 streams. Most traits varied appreciably among traps within populations. Both between-trap distance and microhabitat characteristics such as depth and substrate explained some of the within-population morphological variance. Microhabitat was also associated with genotype at particular loci but there was no genetic isolation by distance, implying that heritable habitat preferences may contribute to microgeographic variation. Our study adds to growing evidence that microgeographic divergence can occur across small spatial scales within individuals' daily dispersal neighborhood where gene flow is expected to be strong.
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Affiliation(s)
- Meghan F Maciejewski
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, 06269
| | - Cynthia Jiang
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, 78705.,Long School of Medicine, UT Health Science Center San Antonio, San Antonio, Texas, 78229
| | - Yoel E Stuart
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, 78705.,Loyola University Chicago, Chicago, Illinois, 60660
| | - Daniel I Bolnick
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, 06269.,Department of Integrative Biology, University of Texas at Austin, Austin, Texas, 78705
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11
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O'Brien DM. Static Scaling and the Evolution of Extreme Canine Size in a Saber-Toothed Cat (Smilodon fatalis). Integr Comp Biol 2019; 59:1303-1311. [PMID: 31120517 DOI: 10.1093/icb/icz054] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The canines of saber-toothed cats are a classic example of an extreme morphology, yet important questions pertaining to their evolution remain unanswered. Recent analyses suggest these structures functioned as tools of intrasexual combat where trait size acts as both a weapon of battle and signal of competitive ability. However, classic skeletal reconstructions suggest saber-tooth canines evolved as specialized hunting tools. Either scenario could have led to the evolution of extreme canine size and distinguishing between these hypotheses is therefore difficult. This is made more challenging by the fact that natural observation of saber-toothed cats is impossible, and biologists must rely on measures of static morphology to study the patterns of selection that favored extreme canine size. Here I analyze the static intraspecific scaling relationship between canine size and body size in the saber-toothed cat, Smilodon fatalis, to determine whether or not extreme canine size functioned as a sexually selected signal. I review the literature surrounding the evolution of sexually selected signals and the methods recently established by O'Brien et al. (2018), show how static scaling relationships can be useful, reliable tools for inferring patterns of selection, especially in fossil organisms, and provide evidence that extreme canine size in saber-toothed cats was not the product of selection for effective sexual signals, but instead evolved as either a pure intrasexually selected weapon or a hunting tool.
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Affiliation(s)
- D M O'Brien
- Department of Biological Sciences, Colby College, 5720 Mayflower Hill Drive, Waterville, ME 04901, USA
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12
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Marklund MHK, Svanbäck R, Faulks L, Breed MF, Scharnweber K, Zha Y, Eklöv P. Asymmetrical habitat coupling of an aquatic predator-The importance of individual specialization. Ecol Evol 2019; 9:3405-3415. [PMID: 30962901 PMCID: PMC6434573 DOI: 10.1002/ece3.4973] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 12/19/2018] [Accepted: 01/16/2019] [Indexed: 01/13/2023] Open
Abstract
Predators should stabilize food webs because they can move between spatially separate habitats. However, predators adapted to forage on local resources may have a reduced ability to couple habitats. Here, we show clear asymmetry in the ability to couple habitats by Eurasian perch-a common polymorphic predator in European lakes. We sampled perch from two spatially separate habitats-pelagic and littoral zones-in Lake Erken, Sweden. Littoral perch showed stronger individual specialization, but they also used resources from the pelagic zone, indicating their ability to couple habitats. In contrast, pelagic perch showed weaker individual specialization but near complete reliance on pelagic resources, indicating their preference to one habitat. This asymmetry in the habitat coupling ability of perch challenges the expectation that, in general, predators should stabilize spatially separated food webs. Our results suggest that habitat coupling might be constrained by morphological adaptations, which in this case were not related to genetic differentiation but were more likely related to differences in individual specialization.
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Affiliation(s)
- Maria H. K. Marklund
- Department of Ecology and Genetics, Limnology, Evolutionary Biology CentreUppsala UniversityUppsalaSweden
- School of Biological Sciences, Department of Ecology and Evolutionary BiologyUniversity of AdelaideNorth TerraceSAAustralia
| | - Richard Svanbäck
- Department of Ecology and Genetics; Animal Ecology, Evolutionary Biology CentreUppsala UniversityUppsalaSweden
| | - Leanne Faulks
- Department of Ecology and Genetics; Animal Ecology, Evolutionary Biology CentreUppsala UniversityUppsalaSweden
- Sugadaira Research StationMountain Science CenterUniversity of TsukubaUedaJapan
| | - Martin F. Breed
- School of Biological Sciences, Department of Ecology and Evolutionary BiologyUniversity of AdelaideNorth TerraceSAAustralia
| | - Kristin Scharnweber
- Department of Ecology and Genetics, Limnology, Evolutionary Biology CentreUppsala UniversityUppsalaSweden
| | - Yinghua Zha
- Department of Ecology and Genetics, Limnology, Evolutionary Biology CentreUppsala UniversityUppsalaSweden
- Department of Microbiology, Tumor and Cell BiologyKarolinska Institutet, NKS BioClinicumSolnaSweden
| | - Peter Eklöv
- Department of Ecology and Genetics, Limnology, Evolutionary Biology CentreUppsala UniversityUppsalaSweden
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13
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Rashid H, Ahmed T. Muscarinic activity in hippocampus and entorhinal cortex is crucial for spatial and fear memory retrieval. Pharmacol Rep 2019; 71:449-456. [PMID: 31003156 DOI: 10.1016/j.pharep.2019.02.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 02/06/2019] [Accepted: 02/07/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND Hippocampus and entorhinal cortex are key players of learning and memory. Despite their established role in memory processes, the contribution of muscarinic receptor activity in these brain regions during memory retrieval remains elusive. This study was aimed to assess the role of hippocampal CA1 and medial entorhinal cortex muscarinic receptors in memory retrieval. METHOD Mice were implanted with bilateral cannulas in the hippocampus CA1 and medial entorhinal cortex. After recovery they were trained for Morris water maze test, novel object recognition test and contextual fear conditioning. Scopolamine was infused 10 min prior to retrieval test. RESULTS Pre-test scopolamine infusion in hippocampal CA1 and medial entorhinal cortex significantly reduced overall exploration of objects (p<0.001). Similarly, pre-retrieval inactivation dorsal hippocampal CA1 and medial entorhinal cortex muscarinic activity caused significant impairment of spatial and fear memories retrieval (p<0.05). CONCLUSION These findings showed vital role of muscarinic activity in retrieving hippocampal and entorhinal cortex dependent memories and suggest a possible target for treating retrograde amnesia.
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Affiliation(s)
- Habiba Rashid
- Neurobiology Laboratory, Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, Pakistan
| | - Touqeer Ahmed
- Neurobiology Laboratory, Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, Pakistan.
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14
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Ingram T, Costa-Pereira R, Araújo MS. The dimensionality of individual niche variation. Ecology 2018; 99:536-549. [DOI: 10.1002/ecy.2129] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 09/26/2017] [Accepted: 12/07/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Travis Ingram
- Department of Zoology; University of Otago; 340 Great King Street Dunedin 9016 New Zealand
| | - Raul Costa-Pereira
- Programa de Pós-graduação em Ecologia e Biodiversidade, Instituto de Biociências; Universidade Estadual Paulista (UNESP); Av. 24-A, 1515 Rio Claro 15807 Brazil
- Instituto de Biociências; Universidade Estadual Paulista (UNESP); Av. 24-A, 1515 Rio Claro 15807 Brazil
| | - Márcio S. Araújo
- Instituto de Biociências; Universidade Estadual Paulista (UNESP); Av. 24-A, 1515 Rio Claro 15807 Brazil
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15
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Carvalho-Rocha V, Lopes BC, Neckel-Oliveira S. Interindividual patterns of resource use in three subtropical Atlantic Forest frogs. AUSTRAL ECOL 2017. [DOI: 10.1111/aec.12552] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Vítor Carvalho-Rocha
- Departamento de Ecologia e Zoologia; Universidade Federal de Santa Catarina; Florianópolis Brazil
- Vítor Carvalho-Rocha; 88040-900 Florianópolis - SC; Bairro Córrego Grande; Brazil
| | - Benedito Cortês Lopes
- Departamento de Ecologia e Zoologia; Universidade Federal de Santa Catarina; Florianópolis Brazil
| | - Selvino Neckel-Oliveira
- Departamento de Ecologia e Zoologia; Universidade Federal de Santa Catarina; Florianópolis Brazil
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16
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Abstract
Food webs (i.e., networks of species and their feeding interactions) share multiple structural features across ecosystems. The factors explaining such similarities are still debated, and the role played by most organismal traits and their intraspecific variation is unknown. Here, we assess how variation in traits controlling predator-prey interactions (e.g., body size) affects food web structure. We show that larger phenotypic variation increases connectivity among predators and their prey as well as total food intake rate. For predators able to eat only a few species (i.e., specialists), low phenotypic variation maximizes intake rates, while the opposite is true for consumers with broader diets (i.e., generalists). We also show that variation sets predator trophic level by determining interaction strengths with prey at different trophic levels. Merging these results, we make two general predictions about the structure of food webs: (i) trophic level should increase with predator connectivity, and (ii) interaction strengths should decrease with prey trophic level. We confirm these predictions empirically using a global dataset of well-resolved food webs. Our results provide understanding of the processes structuring food webs that include functional traits and their naturally occurring variation.
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17
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Lohman BK, Steinel NC, Weber JN, Bolnick DI. Gene Expression Contributes to the Recent Evolution of Host Resistance in a Model Host Parasite System. Front Immunol 2017; 8:1071. [PMID: 28955327 PMCID: PMC5600903 DOI: 10.3389/fimmu.2017.01071] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 08/16/2017] [Indexed: 12/31/2022] Open
Abstract
Heritable population differences in immune gene expression following infection can reveal mechanisms of host immune evolution. We compared gene expression in infected and uninfected threespine stickleback (Gasterosteus aculeatus) from two natural populations that differ in resistance to a native cestode parasite, Schistocephalus solidus. Genes in both the innate and adaptive immune system were differentially expressed as a function of host population, infection status, and their interaction. These genes were enriched for loci controlling immune functions known to differ between host populations or in response to infection. Coexpression network analysis identified two distinct processes contributing to resistance: parasite survival and suppression of growth. Comparing networks between populations showed resistant fish have a dynamic expression profile while susceptible fish are static. In summary, recent evolutionary divergence between two vertebrate populations has generated population-specific gene expression responses to parasite infection, affecting parasite establishment and growth.
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Affiliation(s)
- Brian K Lohman
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, United States
| | - Natalie C Steinel
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, United States.,Department of Medical Education, Dell Medical School, The University of Texas at Austin, Austin, TX, United States
| | - Jesse N Weber
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, United States.,Division of Biological Sciences, The University of Montana, Missoula, MT, United States
| | - Daniel I Bolnick
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, United States
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18
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Marklund MHK, Svanbäck R, Zha Y, Scharnweber K, Eklöv P. The influence of habitat accessibility on the dietary and morphological specialisation of an aquatic predator. OIKOS 2017. [DOI: 10.1111/oik.04094] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Maria H. K. Marklund
- Dept of Ecology and Genetics; Evolutionary Biology Centre, Uppsala Univ., Norbyvägen 18d; SE-75236 Uppsala Sweden
- Water Research Centre and The Environment Institute, School of Biological Sciences, Univ. of Adelaide; North Terrace SA Australia
| | - Richard Svanbäck
- Dept of Ecology and Genetics; Evolutionary Biology Centre, Uppsala Univ., Norbyvägen 18d; SE-75236 Uppsala Sweden
| | - Yinghua Zha
- Dept of Ecology and Genetics; Evolutionary Biology Centre, Uppsala Univ., Norbyvägen 18d; SE-75236 Uppsala Sweden
| | - Kristin Scharnweber
- Dept of Ecology and Genetics; Evolutionary Biology Centre, Uppsala Univ., Norbyvägen 18d; SE-75236 Uppsala Sweden
| | - Peter Eklöv
- Dept of Ecology and Genetics; Evolutionary Biology Centre, Uppsala Univ., Norbyvägen 18d; SE-75236 Uppsala Sweden
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19
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Recent evolution of extreme cestode growth suppression by a vertebrate host. Proc Natl Acad Sci U S A 2017; 114:6575-6580. [PMID: 28588142 DOI: 10.1073/pnas.1620095114] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Parasites can be a major cause of natural selection on hosts, which consequently evolve a variety of strategies to avoid, eliminate, or tolerate infection. When ecologically similar host populations present disparate infection loads, this natural variation can reveal immunological strategies underlying adaptation to infection and population divergence. For instance, the tapeworm Schistocephalus solidus persistently infects 0-80% of threespine stickleback (Gasterosteus aculeatus) in lakes on Vancouver Island. To test whether these heterogeneous infection rates result from evolved differences in immunity, we experimentally exposed laboratory-reared fish from ecologically similar high-infection and no-infection populations to controlled doses of Schistocephalus We observed heritable between-population differences in several immune traits: Fish from the naturally uninfected population initiated a stronger granulocyte response to Schistocephalus infection, and their granulocytes constitutively generate threefold more reactive oxygen species in cell culture. Despite these immunological differences, Schistocephalus was equally successful at establishing initial infections in both host populations. However, the no-infection fish dramatically suppressed tapeworm growth relative to high-infection fish, and parasite size was intermediate in F1 hybrid hosts. Our results show that stickleback recently evolved heritable variation in their capacity to suppress helminth growth by two orders of magnitude. Data from many natural populations indicate that growth suppression is widespread but not universal and, when present, is associated with reduced infection prevalence. Host suppression of helminth somatic growth may be an important immune strategy that aids in parasite clearance or in mitigating the fitness costs of persistent infection.
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20
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Stuart YE, Veen T, Weber JN, Hanson D, Ravinet M, Lohman BK, Thompson CJ, Tasneem T, Doggett A, Izen R, Ahmed N, Barrett RDH, Hendry AP, Peichel CL, Bolnick DI. Contrasting effects of environment and genetics generate a continuum of parallel evolution. Nat Ecol Evol 2017; 1:158. [DOI: 10.1038/s41559-017-0158] [Citation(s) in RCA: 155] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 04/07/2017] [Indexed: 12/25/2022]
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21
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Ahmed NI, Thompson C, Bolnick DI, Stuart YE. Brain morphology of the threespine stickleback ( Gasterosteus aculeatus) varies inconsistently with respect to habitat complexity: A test of the Clever Foraging Hypothesis. Ecol Evol 2017; 7:3372-3380. [PMID: 28515873 PMCID: PMC5433989 DOI: 10.1002/ece3.2918] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 02/06/2017] [Accepted: 02/21/2017] [Indexed: 01/06/2023] Open
Abstract
The Clever Foraging Hypothesis asserts that organisms living in a more spatially complex environment will have a greater neurological capacity for cognitive processes related to spatial memory, navigation, and foraging. Because the telencephalon is often associated with spatial memory and navigation tasks, this hypothesis predicts a positive association between telencephalon size and environmental complexity. The association between habitat complexity and brain size has been supported by comparative studies across multiple species but has not been widely studied at the within-species level. We tested for covariation between environmental complexity and neuroanatomy of threespine stickleback (Gasterosteus aculeatus) collected from 15 pairs of lakes and their parapatric streams on Vancouver Island. In most pairs, neuroanatomy differed between the adjoining lake and stream populations. However, the magnitude and direction of this difference were inconsistent between watersheds and did not covary strongly with measures of within-site environmental heterogeneity. Overall, we find weak support for the Clever Foraging Hypothesis in our study.
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Affiliation(s)
- Newaz I Ahmed
- Department of Integrative Biology University of Texas at Austin Austin TX USA.,Department of Internal Medicine University of Texas-Southwestern Dallas TX USA
| | - Cole Thompson
- Department of Integrative Biology University of Texas at Austin Austin TX USA
| | - Daniel I Bolnick
- Department of Integrative Biology University of Texas at Austin Austin TX USA
| | - Yoel E Stuart
- Department of Integrative Biology University of Texas at Austin Austin TX USA
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22
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Haage M, Angerbjörn A, Elmhagen B, Maran T. An experimental approach to the formation of diet preferences and individual specialisation in European mink. EUR J WILDLIFE RES 2017. [DOI: 10.1007/s10344-017-1091-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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23
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Portella T, Lobón-Cerviá J, Manna LR, Bergallo HG, Mazzoni R. Eco-morphological attributes and feeding habits in coexisting characins. JOURNAL OF FISH BIOLOGY 2017; 90:129-146. [PMID: 27730634 DOI: 10.1111/jfb.13162] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Accepted: 08/30/2016] [Indexed: 06/06/2023]
Abstract
The head morphology and feeding habits of pairs of characin species (family Characidae) that coexist in four different coastal rainforest streams were analysed. Coexisting species differed in size, but were very similar in eco-morphological attributes. Gut analyses revealed differences in feeding preferences for each coexisting species, indicating resource partitioning. A pattern of organization in species pairs that was repeated in the four studied streams was noticed. The pattern consisted of one slightly larger species with a feeding preference for items of allochthonous origin and another smaller species with a preference for autochthonous items. The hypothesis that small morphological differences enable the current coexistence of those species pairs was proposed. Furthermore, the results show ecological equivalence among different species in the studied streams.
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Affiliation(s)
- T Portella
- Departamento de Ecologia, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro-UERJ, Rua São Francisco Xavier, 524, Maracanã, CEP 20550-13, Rio de Janeiro, RJ, Brazil
| | - J Lobón-Cerviá
- Museo Nacional de Ciencias Naturales (CSIC), C/2, José Gutierrez Abascal, Madrid, 28006, Spain
| | - L R Manna
- Departamento de Ecologia, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro-UERJ, Rua São Francisco Xavier, 524, Maracanã, CEP 20550-13, Rio de Janeiro, RJ, Brazil
| | - H G Bergallo
- Departamento de Ecologia, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro-UERJ, Rua São Francisco Xavier, 524, Maracanã, CEP 20550-13, Rio de Janeiro, RJ, Brazil
| | - R Mazzoni
- Departamento de Ecologia, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro-UERJ, Rua São Francisco Xavier, 524, Maracanã, CEP 20550-13, Rio de Janeiro, RJ, Brazil
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24
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Weber JN, Kalbe M, Shim KC, Erin NI, Steinel NC, Ma L, Bolnick DI. Resist Globally, Infect Locally: A Transcontinental Test of Adaptation by Stickleback and Their Tapeworm Parasite. Am Nat 2017; 189:43-57. [DOI: 10.1086/689597] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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25
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Han CS, Jäger HY, Dingemanse NJ. Individuality in nutritional preferences: a multi-level approach in field crickets. Sci Rep 2016; 6:29071. [PMID: 27356870 PMCID: PMC4928176 DOI: 10.1038/srep29071] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 06/14/2016] [Indexed: 11/09/2022] Open
Abstract
Selection may favour individuals of the same population to differ consistently in nutritional preference, for example, because optimal diets covary with morphology or personality. We provided Southern field crickets (Gryllus bimaculatus) with two synthetic food sources (carbohydrates and proteins) and quantified repeatedly how much of each macronutrient was consumed by each individual. We then quantified (i) whether individuals were repeatable in carbohydrate and protein intake rate, (ii) whether an individual's average daily intake of carbohydrates was correlated with its average daily intake of protein, and (iii) whether short-term changes in intake of carbohydrates coincided with changes in intake of protein within individuals. Intake rates were individually repeatable for both macronutrients. However, individuals differed in their relative daily intake of carbohydrates versus proteins (i.e., 'nutritional preference'). By contrast, total consumption varied plastically as a function of body weight within individuals. Body weight-but not personality (i.e., aggression, exploration behaviour)-positively predicted nutritional preference at the individual level as large crickets repeatedly consumed a higher carbohydrate to protein ratio compared to small ones. Our finding of level-specific associations between the consumption of distinct nutritional components demonstrates the merit of applying multivariate and multi-level viewpoints to the study of nutritional preference.
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Affiliation(s)
- Chang S Han
- Behavioural Ecology, Department of Biology, Ludwig-Maximilians University of Munich, Planegg-Martinsried, Germany
| | - Heidi Y Jäger
- Behavioural Ecology, Department of Biology, Ludwig-Maximilians University of Munich, Planegg-Martinsried, Germany
| | - Niels J Dingemanse
- Behavioural Ecology, Department of Biology, Ludwig-Maximilians University of Munich, Planegg-Martinsried, Germany
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26
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27
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A primer on the history of food web ecology: Fundamental contributions of fourteen researchers. FOOD WEBS 2015. [DOI: 10.1016/j.fooweb.2015.07.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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28
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Hughes AR, Hanley TC, Orozco NP, Zerebecki RA. Consumer trait variation influences tritrophic interactions in salt marsh communities. Ecol Evol 2015; 5:2659-72. [PMID: 26257878 PMCID: PMC4523361 DOI: 10.1002/ece3.1564] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 05/15/2015] [Accepted: 05/20/2015] [Indexed: 11/10/2022] Open
Abstract
The importance of intraspecific variation has emerged as a key question in community ecology, helping to bridge the gap between ecology and evolution. Although much of this work has focused on plant species, recent syntheses have highlighted the prevalence and potential importance of morphological, behavioral, and life history variation within animals for ecological and evolutionary processes. Many small-bodied consumers live on the plant that they consume, often resulting in host plant-associated trait variation within and across consumer species. Given the central position of consumer species within tritrophic food webs, such consumer trait variation may play a particularly important role in mediating trophic dynamics, including trophic cascades. In this study, we used a series of field surveys and laboratory experiments to document intraspecific trait variation in a key consumer species, the marsh periwinkle Littoraria irrorata, based on its host plant species (Spartina alterniflora or Juncus roemerianus) in a mixed species assemblage. We then conducted a 12-week mesocosm experiment to examine the effects of Littoraria trait variation on plant community structure and dynamics in a tritrophic salt marsh food web. Littoraria from different host plant species varied across a suite of morphological and behavioral traits. These consumer trait differences interacted with plant community composition and predator presence to affect overall plant stem height, as well as differentially alter the density and biomass of the two key plant species in this system. Whether due to genetic differences or phenotypic plasticity, trait differences between consumer types had significant ecological consequences for the tritrophic marsh food web over seasonal time scales. By altering the cascading effects of the top predator on plant community structure and dynamics, consumer differences may generate a feedback over longer time scales, which in turn influences the degree of trait divergence in subsequent consumer populations.
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Affiliation(s)
| | - Torrance C Hanley
- Marine Science Center, Northeastern University Nahant, Massachusetts
| | - Nohelia P Orozco
- Coastal and Marine Laboratory, Florida State University St. Teresa, Florida
| | - Robyn A Zerebecki
- Marine Science Center, Northeastern University Nahant, Massachusetts
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29
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Stutz WE, Schmerer M, Coates JL, Bolnick DI. Among-lake reciprocal transplants induce convergent expression of immune genes in threespine stickleback. Mol Ecol 2015; 24:4629-46. [PMID: 26118468 DOI: 10.1111/mec.13295] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/22/2015] [Accepted: 06/24/2015] [Indexed: 12/25/2022]
Abstract
Geographic variation in parasite communities can drive evolutionary divergence in host immune genes. However, biotic and abiotic environmental variation can also induce plastic differences in immune function among populations. At present, there is little information concerning the relative magnitudes of heritable vs. induced immune divergence in natural populations. We examined immune gene expression profiles of threespine stickleback (Gasterosteus aculeatus) from six lakes on Vancouver Island, British Columbia. Parasite community composition differs between lake types (large or small, containing limnetic- or benthic-like stickleback) and between watersheds. We observed corresponding differences in immune gene expression profiles among wild-caught stickleback, using a set of seven immune genes representing distinct branches of the immune system. To evaluate the role of environmental effects on this differentiation, we experimentally transplanted wild-caught fish into cages in their native lake, or into a nearby foreign lake. Transplanted individuals' immune gene expression converged on patterns typical of their destination lake, deviating from their native expression profile. Transplant individuals' source population had a much smaller effect, suggesting relatively weak genetic underpinning of population differences in immunity, as viewed through gene expression. This strong environmental regulation of immune gene expression provides a counterpoint to the large emerging literature documenting microevolution and genetic diversification of immune function. Our findings illustrate the value of studying immunity in natural environmental settings where the immune system has evolved and actively functions.
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Affiliation(s)
- William E Stutz
- Department of Integrative Biology, University of Texas at Austin, One University Station C0990, Austin, TX, 78712, USA
| | - Matthew Schmerer
- Department of Integrative Biology, University of Texas at Austin, One University Station C0990, Austin, TX, 78712, USA
| | - Jessica L Coates
- Department of Biology, Spelman College, 350 Spelman Lane SW, Atlanta, GA, 30314, USA
| | - Daniel I Bolnick
- Department of Integrative Biology, University of Texas at Austin, One University Station C0990, Austin, TX, 78712, USA.,Howard Hughes Medical Institute, University of Texas at Austin, One University Station C0990, Austin, TX, 78712, USA
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30
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Ingram T, Jiang Y, Rangel R, Bolnick DI. Widespread positive but weak assortative mating by diet within stickleback populations. Ecol Evol 2015; 5:3352-63. [PMID: 26380669 PMCID: PMC4569031 DOI: 10.1002/ece3.1609] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 06/12/2015] [Accepted: 06/16/2015] [Indexed: 01/04/2023] Open
Abstract
Assortative mating - correlation between male and female traits - is common within populations and has the potential to promote genetic diversity and in some cases speciation. Despite its importance, few studies have sought to explain variation in the extent of assortativeness across populations. Here, we measure assortative mating based on an ecologically important trait, diet as inferred from stable isotopes, in 16 unmanipulated lake populations of three-spine stickleback. As predicted, we find a tendency toward positive assortment on the littoral-pelagic axis, although the magnitude is consistently weak. These populations vary relatively little in the strength of assortativeness, and what variation occurs is not explained by hypothesized drivers including habitat cosegregation, the potential for disruptive selection, costs to choosiness, and the strength of the relationship between diet and body size. Our results support recent findings that most assortative mating is positive, while suggesting that new approaches may be required to identify the environmental variables that drive the evolution of nonrandom mating within populations.
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Affiliation(s)
- Travis Ingram
- Department of Integrative Biology, University of Texas at Austin One University Station C0990, Austin, Texas, 78712
| | - Yuexin Jiang
- Department of Integrative Biology, University of Texas at Austin One University Station C0990, Austin, Texas, 78712
| | - Racine Rangel
- Department of Integrative Biology, University of Texas at Austin One University Station C0990, Austin, Texas, 78712
| | - Daniel I Bolnick
- Department of Integrative Biology, University of Texas at Austin One University Station C0990, Austin, Texas, 78712 ; Howard Hughes Medical Institute, University of Texas at Austin One University Station C0990, Austin, Texas, 78712
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31
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Dietary input of microbes and host genetic variation shape among-population differences in stickleback gut microbiota. ISME JOURNAL 2015; 9:2515-26. [PMID: 25909977 DOI: 10.1038/ismej.2015.64] [Citation(s) in RCA: 186] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 02/11/2015] [Accepted: 03/25/2015] [Indexed: 02/06/2023]
Abstract
To explain differences in gut microbial communities we must determine how processes regulating microbial community assembly (colonization, persistence) differ among hosts and affect microbiota composition. We surveyed the gut microbiota of threespine stickleback (Gasterosteus aculeatus) from 10 geographically clustered populations and sequenced environmental samples to track potential colonizing microbes and quantify the effects of host environment and genotype. Gut microbiota composition and diversity varied among populations. These among-population differences were associated with multiple covarying ecological variables: habitat type (lake, stream, estuary), lake geomorphology and food- (but not water-) associated microbiota. Fish genotype also covaried with gut microbiota composition; more genetically divergent populations exhibited more divergent gut microbiota. Our results suggest that population level differences in stickleback gut microbiota may depend more on internal sorting processes (host genotype) than on colonization processes (transient environmental effects).
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32
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Individual-level niche specialization within populations: emerging areas of study. Oecologia 2015; 178:1-4. [DOI: 10.1007/s00442-014-3209-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 12/15/2014] [Indexed: 10/24/2022]
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