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Axelrod CJ, Yang Y, Grant E, Fleming J, Stone I, Carlson BA, Gordon SP. Evolutionary divergence of plasticity in brain morphology between ecologically divergent habitats of Trinidadian guppies. Evolution 2024:qpae055. [PMID: 38572796 DOI: 10.1093/evolut/qpae055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Indexed: 04/05/2024]
Abstract
Phenotypic plasticity is critical for organismal performance and can evolve in response to natural selection. Brain morphology is often developmentally plastic, affecting animal performance in a variety of contexts. However, the degree to which plasticity of brain morphology evolves has rarely been explored. Here we use Trinidadian guppies (Poecilia reticulata), which are known for their repeated adaptation to high-predation (HP) and low-predation (LP) environments, to examine the evolution and plasticity of brain morphology. We exposed second-generation offspring of individuals from HP and LP sites to two different treatments: predation cues and conspecific social environment. Results show that LP guppies had greater plasticity in brain morphology compared to their ancestral HP population, suggesting that plasticity can evolve in response to environmentally divergent habitats. We also show sexual dimorphism in the plasticity of brain morphology, highlighting the importance of considering sex-specific variation in adaptive diversification. Overall, these results may suggest the evolution of brain morphology plasticity as an important mechanism that allows for ecological diversification and adaptation to divergent habitats.
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Affiliation(s)
- Caleb J Axelrod
- Department of Ecology and Evolution, Cornell University, Ithaca, NY, USA
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Yusan Yang
- Department of Integrative Biology, University of South Florida, Tampa, FL, USA
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Eleanor Grant
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Jorie Fleming
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Isabel Stone
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Bruce A Carlson
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Swanne P Gordon
- Department of Ecology and Evolution, Cornell University, Ithaca, NY, USA
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
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Gordon SP, Axelrod CJ, Bansal U, Gurholt H, Tran S, Yang Y. Embracing the diversity in diverse warning signals. Trends Ecol Evol 2024; 39:225-228. [PMID: 38267287 DOI: 10.1016/j.tree.2024.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 12/20/2023] [Accepted: 01/04/2024] [Indexed: 01/26/2024]
Abstract
Positive frequency-dependent selection should theoretically lead to monomorphic warning coloration. Instead, numerous examples of polymorphic warning signals exist. Biases - for example, in human perception - hinder our appreciation and research of understanding warning signal diversity. We propose strategies to counter such biases and objectively move our field forward.
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Affiliation(s)
- Swanne P Gordon
- Department of Ecology and Evolution, Cornell University, Ithaca, NY, USA.
| | - Caleb J Axelrod
- Department of Ecology and Evolution, Cornell University, Ithaca, NY, USA
| | - Udita Bansal
- Department of Ecology and Evolution, Cornell University, Ithaca, NY, USA
| | - Hannah Gurholt
- Department of Ecology and Evolution, Cornell University, Ithaca, NY, USA
| | - Stephanie Tran
- Department of Ecology and Evolution, Cornell University, Ithaca, NY, USA
| | - Yusan Yang
- Department of Integrative Biology, University of South Florida, Tampa, FL, USA
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3
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Yang Y, Axelrod CJ, Grant E, Earl SR, Urquhart EM, Talbert K, Johnson LE, Walker Z, Hsiao K, Stone I, Carlson BA, López-Sepulcre A, Gordon SP. Evolutionary divergence of developmental plasticity and learning of mating tactics in Trinidadian guppies. J Anim Ecol 2023. [PMID: 38156548 DOI: 10.1111/1365-2656.14043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 11/30/2023] [Indexed: 12/30/2023]
Abstract
Behavioural plasticity is a major driver in the early stages of adaptation, but its effects in mediating evolution remain elusive because behavioural plasticity itself can evolve. In this study, we investigated how male Trinidadian guppies (Poecilia reticulata) adapted to different predation regimes diverged in behavioural plasticity of their mating tactic. We reared F2 juveniles of high- or low-predation population origins with different combinations of social and predator cues and assayed their mating behaviour upon sexual maturity. High-predation males learned their mating tactic from conspecific adults as juveniles, while low-predation males did not. High-predation males increased courtship when exposed to chemical predator cues during development; low-predation males decreased courtship in response to immediate chemical predator cues, but only when they were not exposed to such cues during development. Behavioural changes induced by predator cues were associated with developmental plasticity in brain morphology, but changes acquired through social learning were not. We thus show that guppy populations diverged in their response to social and ecological cues during development, and correlational evidence suggests that different cues can shape the same behaviour via different neural mechanisms. Our study demonstrates that behavioural plasticity, both environmentally induced and socially learnt, evolves rapidly and shapes adaptation when organisms colonize ecologically divergent habitats.
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Affiliation(s)
- Yusan Yang
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
| | - Caleb J Axelrod
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Ecology and Evolution, Cornell University, Ithaca, New York, USA
| | - Elly Grant
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Shayna R Earl
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Biology, University of Louisville, Louisville, Kentucky, USA
| | - Ellen M Urquhart
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Katie Talbert
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Ecology and Evolution, Cornell University, Ithaca, New York, USA
| | - Lauren E Johnson
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Zakiya Walker
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Kyle Hsiao
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Isabel Stone
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Bruce A Carlson
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Andrés López-Sepulcre
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Ecology and Evolution, Cornell University, Ithaca, New York, USA
| | - Swanne P Gordon
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Ecology and Evolution, Cornell University, Ithaca, New York, USA
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Gordon SP, Axelrod CJ. Spatial sorting creates winners and losers. Nat Ecol Evol 2023; 7:1756-1758. [PMID: 37813944 DOI: 10.1038/s41559-023-02217-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Affiliation(s)
- Swanne P Gordon
- Department of Ecology and Evolution, Cornell University, Ithaca, NY, USA.
| | - Caleb J Axelrod
- Department of Ecology and Evolution, Cornell University, Ithaca, NY, USA
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Abstract
Neuroplasticity and evolutionary biology have been prominent fields of study for well over a century. However, they have advanced largely independently, without consideration of the benefits of integration. We propose a new framework by which researchers can begin to examine the evolutionary causes and consequences of neuroplasticity. Neuroplasticity can be defined as changes to the structure, function or connections of the nervous system in response to individual experience. Evolution can alter levels of neuroplasticity if there is variation in neuroplasticity traits within and between populations. Neuroplasticity may be favored or disfavored by natural selection depending on the variability of the environment and the costs of neuroplasticity. Additionally, neuroplasticity may affect rates of genetic evolution in many ways: for example, decreasing rates of evolution by buffering against selection or increasing them via the Baldwin effect, by increasing genetic variation or by incorporating evolved peripheral changes to the nervous system. These mechanisms can be tested using comparative and experimental approaches and by examining patterns and consequences of variation in neuroplasticity among species, populations and individuals.
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Affiliation(s)
- Caleb J Axelrod
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Swanne P Gordon
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Bruce A Carlson
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA.
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Smith S, Mohamed A, Amaral JR, Kusi N, Smith A, Gordon SP, López-Sepulcre A. Rapid evolution of diet choice in an introduced population of Trinidadian guppies. Biol Lett 2023; 19:20220443. [PMID: 36693425 PMCID: PMC9873468 DOI: 10.1098/rsbl.2022.0443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 12/16/2022] [Indexed: 01/26/2023] Open
Abstract
Eco-evolutionary theory has brought an interest in the rapid evolution of functional traits. Among them, diet is an important determinant of ecosystem structure, affecting food web dynamics and nutrient cycling. However, it is largely unknown whether diet, or diet preference, has a hereditary basis and can evolve on contemporary timescales. Here, we study the diet preferences of Trinidadian guppies Poecilia reticulata collected from directly below an introduction site of fish transplanted from a high-predation environment into a low predation site where their densities and competition increased. Behavioural assays on F2 common garden descendants of the ancestral and derived populations showed that diet preference has rapidly evolved in the introduced population in only 12 years (approx. 36 generations). Specifically, we show that the preference for high-quality food generally found in high-predation guppies is lost in the newly derived low-predation population, who show an inertia toward the first encountered food. This result is predicted by theory stating that organisms should evolve less selective diets under higher competition. Demonstrating that diet preference can show rapid and adaptive evolution is important to our understanding of eco-evolutionary feedbacks and the role of evolution in ecosystem dynamics.
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Affiliation(s)
- Shawna Smith
- Department of Biology, Washington University, St. Louis, MO 63130, USA
| | - Amina Mohamed
- Department of Biology, Washington University, St. Louis, MO 63130, USA
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Jeferson Ribeiro Amaral
- Department of Biology, Washington University, St. Louis, MO 63130, USA
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Nana Kusi
- Department of Biology, Washington University, St. Louis, MO 63130, USA
| | - Alexander Smith
- Department of Biology, Washington University, St. Louis, MO 63130, USA
| | - Swanne P. Gordon
- Department of Biology, Washington University, St. Louis, MO 63130, USA
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Andrés López-Sepulcre
- Department of Biology, Washington University, St. Louis, MO 63130, USA
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
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Gordon SP, Burdfield-Steel E, Kirvesoja J, Mappes J. Safety in Numbers: How Color Morph Frequency Affects Predation Risk in an Aposematic Moth. Am Nat 2021; 198:128-141. [PMID: 34143722 DOI: 10.1086/714528] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractPolymorphic warning signals in aposematic systems are enigmatic because predator learning should favor the most common form, creating positive frequency-dependent survival. However, many populations exhibit variation in warning signals. There are various selective mechanisms that can counter positive frequency-dependent selection and lead to temporal or spatial warning signal diversification. Examining these mechanisms and their effects requires first confirming whether the most common morphs are favored at both local and regional scales. Empirical examples of this are uncommon and often include potentially confounding factors, such as a lack of knowledge of predator identity and behavior. We tested how bird behavior influences the survival of three coexisting morphs of the aposematic wood tiger moth Arctia plantaginis offered to a sympatric predator (great tit Parus major) at different frequencies. We found that although positive frequency-dependent selection is present, its strength is affected by predator characteristics and varying prey profitability. These results highlight the need to understand predator foraging in natural communities with variable prey defenses in order to better examine how behavioral interactions shape evolutionary outcomes.
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Duffy MA, García-Robledo C, Gordon SP, Grant NA, Green DA, Kamath A, Penczykowski RM, Rebolleda-Gómez M, Wale N, Zaman L. Model Systems in Ecology, Evolution, and Behavior: A Call for Diversity in Our Model Systems and Discipline. Am Nat 2021; 198:53-68. [PMID: 34143717 DOI: 10.1086/714574] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractEcologists and evolutionary biologists are fascinated by life's variation but also seek to understand phenomena and mechanisms that apply broadly across taxa. Model systems can help us extract generalities from amid all the wondrous diversity, but only if we choose and develop them carefully, use them wisely, and have a range of model systems from which to choose. In this introduction to the Special Feature on Model Systems in Ecology, Evolution, and Behavior (EEB), we begin by grappling with the question, What is a model system? We then explore where our model systems come from, in terms of the skills and other attributes required to develop them and the historical biases that influence traditional model systems in EEB. We emphasize the importance of communities of scientists in the success of model systems-narrow scientific communities can restrict the model organisms themselves. We also consider how our discipline was built around one type of "model scientist"-a history still reflected in the field. This lack of diversity in EEB is unjust and also narrows the field's perspective, including by restricting the questions asked and talents used to answer them. Increasing diversity, equity, and inclusion will require acting at many levels, including structural changes. Diversity in EEB, in both model systems and the scientists who use them, strengthens our discipline.
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Gordon SP, Hendry AP, Reznick DN. Predator-induced Contemporary Evolution, Phenotypic Plasticity, and the Evolution of Reaction Norms in Guppies. COPEIA 2017. [DOI: 10.1643/ce-16-522] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
Theory predicts that the sex linkage of sexually selected traits can influence the direction and rate of evolution and should itself evolve in response to sex-specific selection. Some studies have found intraspecific differences in sex linkage associated with differences in selection pressures, but we know nothing about how fast these differences can evolve. Here we show that introduced guppy populations showing rapid evolution of male coloration also show rapid changes in sex-linkage patterns. A comparison, using hormonal manipulations in females, of introduced populations of different ages suggests a consistent increase of autosomal or X-linked coloration 2 years after introduction from high- to low-predation environments. Twenty years after introduction, populations already show the same pattern of coloration inheritance typical of natural low-predation populations in similar habitats. These results highlight that the contemporary evolution of sexually selected traits ought to be studied in concert with contemporary changes in linkage relationships.
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Gordon SP, Reznick D, Arendt JD, Roughton A, Ontiveros Hernandez MN, Bentzen P, López-Sepulcre A. Selection analysis on the rapid evolution of a secondary sexual trait. Proc Biol Sci 2016; 282:20151244. [PMID: 26290077 DOI: 10.1098/rspb.2015.1244] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Evolutionary analyses of population translocations (experimental or accidental) have been important in demonstrating speed of evolution because they subject organisms to abrupt environmental changes that create an episode of selection. However, the strength of selection in such studies is rarely measured, limiting our understanding of the evolutionary process. This contrasts with long-term, mark-recapture studies of unmanipulated populations that measure selection directly, yet rarely reveal evolutionary change. Here, we present a study of experimental evolution of male colour in Trinidadian guppies where we tracked both evolutionary change and individual-based measures of selection. Guppies were translocated from a predator-rich to a low-predation environment within the same stream system. We used a combination of common garden experiments and monthly sampling of individuals to measure the phenotypic and genetic divergence of male coloration between ancestral and derived fish. Results show rapid evolutionary increases in orange coloration in both populations (1 year or three generations), replicating the results of previous studies. Unlike previous studies, we linked this evolution to an individual-based analysis of selection. By quantifying individual reproductive success and survival, we show, for the first time, that males with more orange and black pigment have higher reproductive success, but males with more black pigment also have higher risk of mortality. The net effect of selection is thus an advantage of orange but not black coloration, as reflected in the evolutionary response. This highlights the importance of considering all components of fitness when understanding the evolution of sexually selected traits in the wild.
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Affiliation(s)
- Swanne P Gordon
- Department of Biology, University of California, Riverside, CA, USA Center of Excellence in Biological Interactions, Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - David Reznick
- Department of Biology, University of California, Riverside, CA, USA
| | - Jeff D Arendt
- Department of Biology, University of California, Riverside, CA, USA
| | - Allen Roughton
- Department of Biology, University of California, Riverside, CA, USA
| | | | - Paul Bentzen
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Andrés López-Sepulcre
- Center of Excellence in Biological Interactions, Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland Institute of Ecology and Environmental Sciences-Paris (iEES), CNRS UMR 7618, Paris, France
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Gordon SP, Chen YY, Yamashita K, Bejar C, Wilshire A, Cheung V. Sex-specific genetic differences in endurance swimming of Trinidadian guppies. Ecol Evol 2015; 5:5318-5328. [PMID: 30151134 PMCID: PMC6102513 DOI: 10.1002/ece3.1789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 09/10/2015] [Accepted: 09/17/2015] [Indexed: 11/17/2022] Open
Abstract
Swim performance is considered a main fitness-determining trait in many aquatic organisms. Swimming is generally the only way most aquatic prey can escape predation, and swimming capacity is directly linked to food capture, habitat shifts, and reproduction. Therefore, evolutionary studies of swim performance are important to understand adaptation to aquatic environments. Most studies, however, concentrate on the importance of burst-swim responses to predators, and little is known about its effect on endurance. Even fewer studies associate differences in organism swim capabilities to key gender-specific responses. In this experiment, we assess the gender-specific genetic basis of swimming endurance among four different populations of Trinidadian guppies adapted to different predation regimes. Our results show that second-generation common-garden females adapted to a low-predation environment show longer swim endurance than fish adapted to a high-predation environment. We also find an expected effect of lowered swimming endurance during pregnancy, but interestingly, it did not matter whether the females were in advanced stages of pregnancy, which severely changes body morphology, versus mid-pregnancy. Males did not show the same trends across populations, and overall had lower swim endurances than female fish combined even when accounting for size differences. Populations recently transplanted from high- to low-predation environments showed similar endurance to natural low-predation environments in one population but not the other. This study highlights the importance of endurance in the adaptation of aquatic organisms to different predation regimes.
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Affiliation(s)
- Swanne P. Gordon
- Centre of Excellence in Biological InteractionsDepartment of Biological and Environmental SciencesUniversity of JyväskyläJyväskyläFinland
- Department of BiologyUniversity of CaliforniaRiversideCalifornia
| | - Yun Yi Chen
- Department of BiologyUniversity of CaliforniaRiversideCalifornia
| | | | | | - Adam Wilshire
- Department of BiologyUniversity of CaliforniaRiversideCalifornia
| | - Vinson Cheung
- Department of BiologyUniversity of CaliforniaRiversideCalifornia
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Gordon SP, Kokko H, Rojas B, Nokelainen O, Mappes J. Colour polymorphism torn apart by opposing positive frequency-dependent selection, yet maintained in space. J Anim Ecol 2015; 84:1555-64. [DOI: 10.1111/1365-2656.12416] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 06/22/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Swanne P. Gordon
- Centre of Excellence in Biological Interactions; Department of Biological and Environmental Sciences; University of Jyväskylä; yväskylä Finland
| | - Hanna Kokko
- Institute of Evolutionary Biology and Environmental Studies; University of Zurich; Zurich Switzerland
| | - Bibiana Rojas
- Centre of Excellence in Biological Interactions; Department of Biological and Environmental Sciences; University of Jyväskylä; yväskylä Finland
| | - Ossi Nokelainen
- Centre of Excellence in Biological Interactions; Department of Biological and Environmental Sciences; University of Jyväskylä; yväskylä Finland
- Department of Zoology; University of Cambridge; Cambridge UK
| | - Johanna Mappes
- Centre of Excellence in Biological Interactions; Department of Biological and Environmental Sciences; University of Jyväskylä; yväskylä Finland
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López-Sepulcre A, Gordon SP, Paterson IG, Bentzen P, Reznick DN. Beyond lifetime reproductive success: the posthumous reproductive dynamics of male Trinidadian guppies. Proc Biol Sci 2013; 280:20131116. [PMID: 23740786 PMCID: PMC3774245 DOI: 10.1098/rspb.2013.1116] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 05/14/2013] [Indexed: 11/12/2022] Open
Abstract
In semelparous populations, dormant germ banks (e.g. seeds) have been proposed as important in maintaining genotypes that are adaptive at different times in fluctuating environments. Such hidden storage of genetic diversity need not be exclusive to dormant banks. Genotype diversity may be preserved in many iteroparous animals through sperm-storage mechanisms in females. This allows males to reproduce posthumously and increase the effective sizes of seemingly female-biased populations. Although long-term sperm storage has been demonstrated in many organisms, the understanding of its importance in the wild is very poor. We here show the prevalence of male posthumous reproduction in wild Trinidadian guppies, through the combination of mark-recapture and pedigree analyses of a multigenerational individual-based dataset. A significant proportion of the reproductive population consisted of dead males, who could conceive up to 10 months after death (the maximum allowed by the length of the dataset), which is more than twice the estimated generation time. Demographic analysis shows that the fecundity of dead males can play an important role in population growth and selection.
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Affiliation(s)
- Andrés López-Sepulcre
- Laboratoire d'Ecologie et Evolution, CNRS UMR 7625, École Normale Supérieure de Paris, Paris, France.
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15
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Abstract
Evolutionary theory predicts that the sex linkage of sexually selected traits can influence the direction and rate of evolutionary change, and also itself be subject to selection. Theory abounds on how sex-specific selection, mate choice, or other phenomena should favor different types of sex-linked inheritance, yet evidence in nature remains limited. Here, we use hormone assays in Trinidadian guppies to explore the extent to which linkage of male coloration differs among populations adapted to varying predation regimes. Results show there is consistently higher degree of X- and autosomal linkage in body coloration among populations adapted to low-predation environments. More strikingly, analyses of an introduced population of guppies from a high- to a low-predation environment suggest that this difference can change in 50 years or less.
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Affiliation(s)
- Swanne P Gordon
- Department of Biology, University of California, Riverside, CA 92521 E-mail: Ecologie-Evolution, CNRS UMR 7625, École Normale Supéieure, Paris, France
| | - Andrés López-Sepulcre
- Department of Biology, University of California, Riverside, CA 92521 E-mail: Ecologie-Evolution, CNRS UMR 7625, École Normale Supéieure, Paris, France
| | - David N Reznick
- Department of Biology, University of California, Riverside, CA 92521 E-mail: Ecologie-Evolution, CNRS UMR 7625, École Normale Supéieure, Paris, France
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Othman M, Gordon SP, Iscoe S. Repeated inspiratory occlusions in anesthetized rats acutely increase blood coagulability as assessed by thromboelastography. Respir Physiol Neurobiol 2010; 171:61-6. [PMID: 20097311 DOI: 10.1016/j.resp.2010.01.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 01/15/2010] [Accepted: 01/15/2010] [Indexed: 01/13/2023]
Abstract
Many of the components contributing to coagulability are enhanced by repeated episodes of hypoxia, as occurs in obstructive sleep apnea, but no one has yet measured the global hemostatic properties of blood in an animal model of this disease. Using thromboelastography, a hemostatic assay, we measured hemostasis in six pentobarbital-anesthetized rats before and after 3h of repeated inspiratory occlusions lasting 30s applied every 2 min and compared the results to those in six identically prepared rats before and after 3h of resting breathing. Rats subjected to occlusions displayed faster onset of clotting (p<0.031) and more rapid coagulation (p<0.031). Thus, repeated inspiratory occlusions acutely cause hypercoagulability in rats. Thromboelastography, a simple test of hemostasis, may help evaluate the factors responsible for this increase and, in patients with obstructive sleep apnea, the risk of future cardiovascular disease.
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Affiliation(s)
- M Othman
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada
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Weese DJ, Gordon SP, Hendry AP, Kinnison MT. Spatiotemporal variation in linear natural selection on body color in wild guppies (Poecilia reticulata). Evolution 2010; 64:1802-15. [PMID: 20067520 DOI: 10.1111/j.1558-5646.2010.00945.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We conducted 10 mark-recapture experiments in natural populations of Trinidadian guppies to test hypotheses concerning the role of viability selection in geographic patterns of male color variation. Previous work has reported that male guppies are more colorful in low-predation sites than in high-predation sites. This pattern of phenotypic variation has been theorized to reflect differences in the balance between natural (viability) selection that disfavors bright male color (owing to predation) and sexual selection that favors bright color (owing to female choice). Our results support the prediction that male color is disfavored by viability selection in both predation regimes. However, it does not support the prediction that viability selection against male color is weaker in low-predation experiments. Instead, some of the most intense bouts of selection against color occurred in low-predation experiments. Our results illustrate considerable spatiotemporal variation in selection among experiments, but such variation was not generally correlated with local patterns of color diversity. More complex selective interactions, possibly including the indirect effects of predators on variation in mating behavior, as well as other environmental factors, might be required to more fully explain patterns of secondary sexual trait variation in this system.
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Affiliation(s)
- Dylan J Weese
- School of Biology and Ecology, University of Maine, 5751 Murray Hall, Orono, Maine 04469, USA.
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Gordon SP, Reznick DN, Kinnison MT, Bryant MJ, Weese DJ, Räsänen K, Millar NP, Hendry AP. Adaptive changes in life history and survival following a new guppy introduction. Am Nat 2009; 174:34-45. [PMID: 19438322 DOI: 10.1086/599300] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Numerous studies of wild populations have shown that phenotypic traits can change adaptively on short timescales, but very few studies have considered coincident changes in major fitness components. We here examine adaptive changes in life-history traits and survival rates for wild guppies introduced into new environments. Female life-history traits in the derived (Damier River) populations diverged from the ancestral (Yarra River) population, as a result of adaptation to predation regime (high vs. low) and other aspects of the local river. Moreover, some components of the derived Damier populations, particularly juveniles, now show higher survival in the Damier than do contemporary representatives from the ancestral Yarra population. These results suggest that adaptive change can improve survival rates after fewer than 10 years (fewer than 30 guppy generations) in a new environment.
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Affiliation(s)
- Swanne P Gordon
- Department of Biology, University of California, Riverside, California 92521, USA.
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Abstract
We use an experimental introduction in nature to examine factors that influence parallel evolution. In 1996, 200 high-predation guppies (Poecilia reticulata) from the Yarra River were introduced into the Damier River, which previously lacked guppies. Eight years later, we quantified the colour of wild-caught guppies ('phenotypic' divergence) and lab-reared guppies ('genetic' divergence) from low- and high-predation environments in both rivers. Phenotypic and genetic divergence between predation environments within the Yarra was evident for black and for orange. Phenotypic divergence within the Damier was parallel to the Yarra for black but not for orange. Genetic divergence was absent between predation environments within the Damier, but was evident when comparing both Damier populations to their Yarra ancestors. The evolution of male colour thus depends on factors other than the simple contrast between 'high' and 'low' predation. We suggest that the parallel evolution of male signalling traits may sometimes first require the parallel evolution of female preferences.
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Affiliation(s)
- N Karim
- Redpath Museum and Department of Biology, McGill University, Montréal, QC, Canada
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Sullivan A, Hamster H, Gordon SP, Falcone RW, Nathel H. Propagation of intense, ultrashort laser pulses in plasmas. Opt Lett 1994; 19:1544-1546. [PMID: 19855578 DOI: 10.1364/ol.19.001544] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We have investigated the propagation of terawatt-power laser pulses in gases. The spatial distribution of focused radiation is modified by refraction that results from the spatially inhomogeneous refractive index of the plasma generated by high field ionization. We observe Thomson scattering, stimulated Raman scattering, and large wavelength shifting of the laser light.
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Gordon SP, Donnelly T, Sullivan A, Hamster H, Falcone RW. X rays from microstructured targets heated by femtosecond lasers. Opt Lett 1994; 19:484-486. [PMID: 19844348 DOI: 10.1364/ol.19.000484] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We have demonstrated efficient conversion of ultrashort-pulse laser energy to x rays with energies above 1 keV, using laser-produced plasmas generated on a variety of microstructured surfaces. Lithographically produced grating targets generated 0.1 mJ of kilo-electron-volt x rays, and porous gold and aluminum targets emitted 1 mJ. This represents an improvement of a factor of 100 over flat targets. The K-shell emission spectrum of porous aluminum was composed primarily of heliumlike spectral lines.
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Manning WJ, Silverman DI, Gordon SP, Krumholz HM, Douglas PS. Cardioversion from atrial fibrillation without prolonged anticoagulation with use of transesophageal echocardiography to exclude the presence of atrial thrombi. N Engl J Med 1993; 328:750-5. [PMID: 8437595 DOI: 10.1056/nejm199303183281102] [Citation(s) in RCA: 260] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACKGROUND Because atrial thrombi are poorly detected by conventional noninvasive techniques such as transthoracic echocardiography, patients with prolonged atrial fibrillation usually receive several weeks of oral anticoagulation therapy before cardioversion is attempted. We wondered whether transesophageal echocardiography, an accurate method of detecting atrial thrombi, would allow early cardioversion to be performed safely if no thrombi were identified. METHODS A total of 669 consecutive patients admitted with the diagnosis of atrial fibrillation were screened. Patients were excluded if they were receiving long-term anticoagulation, if the duration of atrial fibrillation was two days or less, if they were not candidates for cardioversion, or if transesophageal echocardiography was contraindicated. Of 119 qualifying patients, 94 agreed to participate; the average duration of atrial fibrillation was 4.5 weeks. Participating patients underwent transthoracic echocardiography and transesophageal echocardiography followed by cardioversion if no thrombi were seen. Short-term anticoagulation with heparin was used in 80 patients before cardioversion, and 60 patients received warfarin for one month after cardioversion. RESULTS Fourteen atrial thrombi were identified in 12 patients (13 percent), and 12 of the 14 thrombi were visualized only on transesophageal echocardiography. Cardioversion was deferred in all 12 patients. Two of these 12 patients died suddenly; 4 of the 10 surviving patients underwent uneventful cardioversion after prolonged oral anticoagulation. Seventy-eight of the 82 patients without thrombi underwent successful cardioversion to sinus rhythm (47 by means of antiarrhythmic drugs and 31 by electrical cardioversion), all without long-term oral anticoagulation. None of these patients (95 percent confidence interval, 0 to 4.6 percent) had an embolic event. CONCLUSIONS In patients with atrial fibrillation of unknown or prolonged duration who are not receiving long-term anticoagulation, atrial thrombi are detected by transesophageal echocardiography in only a small minority (13 percent in our study). Our preliminary data suggest that if transesophageal echocardiography excludes the presence of thrombi, early cardioversion can be performed safely without the need for prolonged oral anticoagulation before the procedure.
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Affiliation(s)
- W J Manning
- Charles A. Dana Research Institute, Beth Israel Hospital, Boston, MA
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Cohen DJ, Kuntz RE, Gordon SP, Piana RN, Safian RD, McKay RG, Baim DS, Grossman W, Diver DJ. Predictors of long-term outcome after percutaneous balloon mitral valvuloplasty. N Engl J Med 1992; 327:1329-35. [PMID: 1406834 DOI: 10.1056/nejm199211053271901] [Citation(s) in RCA: 153] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Percutaneous balloon mitral valvuloplasty is known to produce short-term hemodynamic and symptomatic improvement in many patients with mitral stenosis. Comprehensive assessment of the clinical usefulness of balloon valvuloplasty requires evaluation of patients' long-term outcomes. METHODS We performed balloon mitral valvuloplasty in 146 patients between October 1, 1985, and October 1, 1991. Base-line demographic, clinical, echocardiographic, and hemodynamic variables were evaluated in order to identify predictors of long-term event-free survival. RESULTS Balloon mitral valvuloplasty was completed successfully in 136 (93 percent) of the patients in whom the procedure was attempted; it resulted in an increase in the mean (+/- SD) mitral-valve area from 1.0 +/- 0.4 to 2.1 +/- 0.9 cm2 and a decrease in the mean transmitral pressure gradient from 14 +/- 5 to 6 +/- 3 mm Hg (P < 0.001 for both comparisons). The estimated overall five-year survival rate was 76 +/- 5 percent, and the estimated five-year event-free survival rate (the percentage of patients without mitral-valve replacement, repeat valvuloplasty, or death from cardiac causes) was 51 +/- 6 percent. According to multivariate Cox proportional-hazards analysis, the independent predictors of longer event-free survival were a lower mitral-valve echocardiographic score (a measure of mitral-valve deformity; range, 0 for a normal valve to 16 for a seriously deformed valve; P < 0.001), lower left ventricular end-diastolic pressure (P = 0.001), and a lower New York Heart Association (NYHA) functional class (P = 0.04). Patients with no risk factors for early restenosis or only one risk factor (echocardiographic score > 8, left ventricular end-diastolic pressure > 10 mm Hg, or NYHA functional class IV) had a predicted five-year event-free survival rate of 60 to 84 percent, whereas patients with two or three risk factors had a predicted five-year event-free survival rate of only 13 to 41 percent. CONCLUSIONS Balloon mitral valvuloplasty as a treatment for selected patients with mitral stenosis has good long-term results. The long-term outcome after this procedure can be predicted on the basis of patients' base-line characteristics.
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Affiliation(s)
- D J Cohen
- Charles A. Dana Research Institute, Harvard Medical School, Boston, MA
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Abstract
We assessed the effects of chest wall distortion, changes in lung volume, and abolition of airway smooth muscle tone on the discharge patterns of 92 pulmonary slowly adapting receptors (SAR) in decerebrate, spontaneously breathing cats. Distortion resulted from their inspiratory efforts against an occluded airway at functional residual capacity and at increased end-expiratory lung volumes. Approximately 40% of SAR increased discharge frequencies during occlusions. Modulation of SAR discharge during occlusions persisted after administration of atropine to eliminate airway smooth muscle tone. Phasic modulation of SAR discharge was eliminated during no-inflation tests after paralyzing the cats and ventilating them on a cycle-triggered pump. We conclude 1) parasympathetic modulation of airway smooth muscle tone makes no obvious contribution to SAR discharge in spontaneously breathing cats; 2) the no-inflation test (withholding of lung inflation during neural inspiration) in paralyzed and ventilated cats is a valid test for the presence of projections from SAR to medullary respiratory neurons; and 3) in the absence of tidal volume changes, distortion stimulates some SAR. Sensory feedback from receptors in the lung, not just those in the chest wall, may therefore provide information about abnormal chest wall configurations.
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Affiliation(s)
- S Iscoe
- Department of Physiology, Queen's University, Kingston, Ontario, Canada
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Gordon SP, Douglas PS, Come PC, Manning WJ. Two-dimensional and Doppler echocardiographic determinants of the natural history of mitral valve narrowing in patients with rheumatic mitral stenosis: implications for follow-up. J Am Coll Cardiol 1992; 19:968-73. [PMID: 1552121 DOI: 10.1016/0735-1097(92)90280-z] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Fifty patients with rheumatic mitral stenosis were studied with serial two-dimensional and Doppler echocardiography to determine the natural history of changes in mitral valve area and its relation to transmitral gradients and mitral valve morphology. Over the 39-month observation period (range 7 to 74 months) the decline in valve area was 0.09 +/- 0.21 cm2/year. In addition, there were significant increases in total echocardiographic score (p = 0.0001), severity of mitral anulus calcification (p = 0.05) and severity of mitral regurgitation (p = 0.0007). Patients with an echocardiographic score greater than or equal to 8 had a more progressive course. In addition, patients with a more progressive course (decline in valve area greater than or equal to 0.1 cm2/year) had a significantly greater initial mean gradient (p = 0.01), peak gradient (p = 0.007) and total echocardiographic score (p = 0.0008). Initial valve area did not correlate with the rate of stenosis progression. Of 22 patients with an echocardiographic score less than 8 and a peak mitral gradient less than 10 mm Hg, only 1 patient (5%) had a more progressive course, compared with 80% of those with a total echocardiographic score greater than or equal to 8 and a gradient greater than or equal to 10 mm Hg. The rate of mitral valve narrowing in individual patients with rheumatic mitral stenosis is variable. Patients whose valve disease progresses rapidly are those with a greater mitral valve echocardiographic score and higher peak and mean transmitral gradients.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S P Gordon
- Charles A. Dana Research Institute, Boston, Massachusetts
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Abstract
The pharmacokinetics of diltiazem and its major metabolites, deacetyldiltiazem and N-monodemethyl-diltiazem, were studied after single and chronic oral administration in eight patients aged 45 to 69 years with unstable angina pectoris, treated by diltiazem, 120 mg t.i.d. After a single oral dose the time to peak plasma diltiazem concentration was 3.4 (2.1 to 5.0) hours and the elimination half-life was 6.6 hours (4.4 to 10.8 hours). These were unchanged after repeated oral administration (16 to 19 doses). The mean trough (8 hours after administration) plasma diltiazem level after six consecutive doses was 167 micrograms/L (63 to 286 micrograms/L) and was thereafter stable. With chronic administration the AUC increased by a factor of 2.24 +/- 0.31 (SEM; P less than 0.01). Plasma protein binding of diltiazem in these patients ranged from 83% to 93% whereas deacetyldiltiazem binding ranged from 58% to 75%. Plasma protein binding was independent of drug concentration and duration of treatment. Thus an average dose of 120 mg diltiazem given every 8 hours would appear to be a suitable regimen of treatment in most patients with angina pectoris, although users should be aware that there is a significant interpatient variability in steady-state diltiazem concentrations and that a significant accumulation of diltiazem occurs with chronic therapy.
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Affiliation(s)
- J Hung
- Department of Cardiovascular Medicine, Sir Charles Gairdner Hospital, Nedlands, Western Australia
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