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Hiillos AL, Rony I, Rueckert S, Knott KE. Coinfection patterns of two marine apicomplexans are not associated with genetic diversity of their polychaete host. J Eukaryot Microbiol 2023; 70:e12932. [PMID: 35711085 PMCID: PMC10084031 DOI: 10.1111/jeu.12932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/21/2022] [Accepted: 05/08/2022] [Indexed: 01/13/2023]
Abstract
Coinfections of two or more parasites within one host are more of a rule than an exception in nature. Interactions between coinfecting parasites can greatly affect their abundance and prevalence. Characteristics of the host, such as genetic diversity, can also affect the infection dynamics of coinfecting parasites. Here, we investigate for the first time the association of coinfection patterns of two marine apicomplexans, Rhytidocystis sp. and Selenidium pygospionis, with the genetic diversity of their host, the polychaete Pygospio elegans, from natural populations. Host genetic diversity was determined with seven microsatellite loci and summarized as allelic richness, inbreeding coefficient, and individual heterozygosity. We detected nonsignificant correlations between infection loads and both individual host heterozygosity and population genetic diversity. Prevalence and infection load of Rhytidocystis sp. were higher than those of S. pygospionis, and both varied spatially. Coinfections were common, and almost all hosts infected by S. pygospionis were also infected by Rhytidocystis sp. Rhytidocystis sp. infection load was significantly higher in dual infections. Our results suggest that factors other than host genetic diversity might be more important in marine apicomplexan infection patterns and experimental approaches would be needed to further determine how interactions between the apicomplexans and their host influence infection.
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Affiliation(s)
- Anna-Lotta Hiillos
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Irin Rony
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Sonja Rueckert
- School of Applied Sciences, Edinburgh Napier University, Edinburgh, UK.,Centre for Conservation and Restoration Science, Edinburgh Napier University, Edinburgh, UK
| | - K Emily Knott
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
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Kerstes NA, Bérénos C, Martin OY. Coevolving parasites and population size shape the evolution of mating behaviour. BMC Evol Biol 2013; 13:29. [PMID: 23379749 PMCID: PMC3570307 DOI: 10.1186/1471-2148-13-29] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 01/30/2013] [Indexed: 11/27/2022] Open
Abstract
Background Coevolution with parasites and population size are both expected to influence the evolution of mating rates. To gain insights into the interaction between these dual selective factors, we used populations from a coevolution experiment with the red flour beetle, Tribolium castaneum, and its microsporidian parasite, Nosema whitei. We maintained each experimental population at two different population sizes. We assayed the mating behaviour of both males and females from coevolved and paired non-coevolved control populations after 24 generations of coevolution with parasites. Results Males from large, coevolved populations (i.e. ancestors were exposed to parasites) showed a reduced eagerness to mate compared to males from large, non-coevolved populations. But in small populations, coevolution did not lead to decreased male mating rates. Coevolved females from both large and small populations appeared to be more willing to accept mating than non-coevolved females. Conclusions This study provides unique, experimental insights into the combined roles of coevolving parasites and population size on the evolution of mating rate. Furthermore, we find that males and females respond differently to the same environmental conditions. Our results show that parasites can be key determinants of the sexual behaviour of their hosts.
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Affiliation(s)
- Niels Ag Kerstes
- ETH Zürich, Institute of Integrative Biology, Experimental Ecology, Zürich, Switzerland.
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Kerstes NAG, Bérénos C, Schmid-Hempel P, Wegner KM. Antagonistic experimental coevolution with a parasite increases host recombination frequency. BMC Evol Biol 2012; 12:18. [PMID: 22330615 PMCID: PMC3293731 DOI: 10.1186/1471-2148-12-18] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 02/13/2012] [Indexed: 11/10/2022] Open
Abstract
Background One of the big remaining challenges in evolutionary biology is to understand the evolution and maintenance of meiotic recombination. As recombination breaks down successful genotypes, it should be selected for only under very limited conditions. Yet, recombination is very common and phylogenetically widespread. The Red Queen Hypothesis is one of the most prominent hypotheses for the adaptive value of recombination and sexual reproduction. The Red Queen Hypothesis predicts an advantage of recombination for hosts that are coevolving with their parasites. We tested predictions of the hypothesis with experimental coevolution using the red flour beetle, Tribolium castaneum, and its microsporidian parasite, Nosema whitei. Results By measuring recombination directly in the individuals under selection, we found that recombination in the host population was increased after 11 generations of coevolution. Detailed insights into genotypic and phenotypic changes occurring during the coevolution experiment furthermore helped us to reconstruct the coevolutionary dynamics that were associated with this increase in recombination frequency. As coevolved lines maintained higher genetic diversity than control lines, and because there was no evidence for heterozygote advantage or for a plastic response of recombination to infection, the observed increase in recombination most likely represented an adaptive host response under Red Queen dynamics. Conclusions This study provides direct, experimental evidence for an increase in recombination frequency under host-parasite coevolution in an obligatory outcrossing species. Combined with earlier results, the Red Queen process is the most likely explanation for this observation.
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Affiliation(s)
- Niels A G Kerstes
- ETH Zürich, Institute of Integrative Biology, Experimental Ecology, CH-8092 Zürich, Switzerland.
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Whitehorn PR, Tinsley MC, Brown MJF, Darvill B, Goulson D. Genetic diversity, parasite prevalence and immunity in wild bumblebees. Proc Biol Sci 2011; 278:1195-202. [PMID: 20926436 PMCID: PMC3049068 DOI: 10.1098/rspb.2010.1550] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 09/17/2010] [Indexed: 01/03/2023] Open
Abstract
Inbreeding and a consequent loss of genetic diversity threaten small, isolated populations. One mechanism by which genetically impoverished populations may become extinct is through decreased immunocompetence and higher susceptibility to parasites. Here, we investigate the relationship between immunity and inbreeding in bumblebees, using Hebridean island populations of Bombus muscorum. We sampled nine populations and recorded parasite prevalence and measured two aspects of immunity: the encapsulation response and levels of phenoloxidase (PO). We found that prevalence of the gut parasite Crithidia bombi was higher in populations with lower genetic diversity. Neither measure of immune activity was correlated with genetic diversity. However, levels of PO declined with age and were also negatively correlated with parasite abundance. Our results suggest that as insect populations lose heterozygosity, the impact of parasitism will increase, pushing threatened populations closer to extinction.
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Affiliation(s)
- Penelope R Whitehorn
- School of Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, UK.
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5
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Drayton JM, Jennions MD. Inbreeding and measures of immune function in the cricket Teleogryllus commodus. Behav Ecol 2011. [DOI: 10.1093/beheco/arr005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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6
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Husseneder C, Simms DM, Aluko GK, Delatte J. Colony breeding system influences cuticular bacterial load of Formosan subterranean termite (Isoptera: Rhinotermitidae) workers. ENVIRONMENTAL ENTOMOLOGY 2010; 39:1715-1723. [PMID: 22182534 DOI: 10.1603/en09238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The goal of this study was to test whether the breeding system and/or the degree of inbreeding of field colonies of the Formosan subterranean termite, Coptotermes formosanus, Shiraki (Isoptera: Rhinotermitidae) influences bacterial load on the cuticle of foraging workers. We enumerated bacterial load on the cuticle of groups of workers foraging in 20 inground monitoring stations surrounding the French Market in New Orleans, LA, and identified bacteria species using 16S rRNA gene sequencing. We used microsatellite genotyping to assign the 20 worker groups to seven simple family colonies (headed by a single pair of reproductives) and four extended family colonies (headed by multiple inbreeding reproductives) with a wide range of degrees of inbreeding. Workers from extended family colonies had a higher bacterial load than those from simple family colonies; however, bacterial load was not significantly correlated to the degree of inbreeding, possibly because of confounding factors in colony life history, such as age and/or size of colonies. Colonies with high bacterial load did not have a higher proportion of entomopathogens, and thus, bacterial load is not necessarily an indicator for disease risk. The majority of bacteria cultured from the cuticle of termites were soil bacteria with no known pathology against termites.
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Affiliation(s)
- Claudia Husseneder
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA.
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7
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Inbreeding and caste-specific variation in immune defence in the ant Formica exsecta. Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-010-1090-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Valtonen TM, Roff DA, Rantala MJ. Analysis of the effects of early nutritional environment on inbreeding depression in Drosophila melanogaster. J Evol Biol 2010; 24:196-205. [PMID: 21044202 DOI: 10.1111/j.1420-9101.2010.02157.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The impact of nutritional deficiencies early in life in determining life-history variation in organisms is well recognized. The negative effects of inbreeding on fitness are also well known. Contrary to studies on vertebrates, studies on invertebrates are not consistent with the observation that inbreeding compromises resistance to parasites and pathogens. In this study, we investigated the effect of early nutrition on the magnitude of inbreeding depression in development time, adult body size and adult resistance to the bacterium Serratia marcescens in Drosophila melanogaster. We found that early nutritional environment had no effect on the magnitude of inbreeding depression in development time or adult body size but may have played a small role in adult resistance to the bacterial infection. Estimates of heritabilities for development time under the poor nutritional environment were larger than those measured under the standard nutritional conditions.
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Affiliation(s)
- T M Valtonen
- Department of Biology, Section of Ecology, University of Turku, Turku, Finland.
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9
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O'Donnell D, Armbruster P. Inbreeding depression affects life-history traits but not infection by Plasmodium gallinaceum in the Asian tiger mosquito, Aedes albopictus. INFECTION GENETICS AND EVOLUTION 2010; 10:669-77. [PMID: 20359551 DOI: 10.1016/j.meegid.2010.03.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 03/21/2010] [Accepted: 03/23/2010] [Indexed: 10/19/2022]
Abstract
Emerging and re-emerging vector-borne diseases represent an increasingly significant public health challenge. While geographic variation among populations of vector species for susceptibility to pathogen infection and vector competence has been thoroughly documented, relatively little attention has been devoted to understanding the ultimate evolutionary causes of this intraspecific variation. Local genetic drift is known to influence genetic differentiation among populations for a variety of container-inhabiting mosquito species, including Aedes albopictus. Because genetic drift is expected to reduce genetic variation and lead to the accumulation of (partially) recessive deleterious alleles, we hypothesized that reduced genetic variation might affect susceptibility to pathogen infection in a model pathogen-vector system. We therefore created replicate inbred (two generations of full-sib mating, expected f=0.375) and control (expected f approximately 0.07) lines of Ae. albopictus and measured life-history traits including larval survivorship, adult longevity, and female wing length (body size) as well as susceptibility to infection by a model pathogen, Plasmodium gallinaceum. Inbred mosquitoes had significantly reduced larval survivorship and female adult longevity but inbreeding did not affect male adult longevity or female wing length (body size). Furthermore, there was no effect of inbreeding on susceptibility to infection by P. gallinaceum. Therefore, while our results did not support the hypothesis that reduced genetic variation influences susceptibility to pathogen infection in this system, we did find evidence for an effect of reduced genetic variation on female adult longevity, an important component of vectorial capacity. We suggest that additional research is needed to elucidate the genetic underpinnings of intraspecific variation in traits related to disease transmission and discuss the implications of our results for the efficacy of creating transgenic strains refractory to disease transmission.
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Affiliation(s)
- Deborah O'Donnell
- Department of Biology, Georgetown University, 37th and O Sts. NW, Washington, DC 20057, United States
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Leisnham PT, Sala LM, Juliano SA. Geographic variation in adult survival and reproductive tactics of the mosquito Aedes albopictus. JOURNAL OF MEDICAL ENTOMOLOGY 2008; 45:210-21. [PMID: 18402136 PMCID: PMC2583062 DOI: 10.1603/0022-2585(2008)45[210:gviasa]2.0.co;2] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Climate differences across latitude can result in seasonal constraints and selection on life history characters. Since Aedes albopictus (Skuse) invaded North America in the mid-1980s, it has spread across a range of approximately 14 degrees latitude and populations in the north experience complete adult mortality due to cold winter temperatures that are absent in the south. Life table experiments were conducted to test for differences in the adult survival and reproductive schedules of Ae. albopictus females from two populations from the northern (Bloomington, IN [BL] and Manassas, VA [VA]; approximately 39 degrees N) and southern (Tampa, FL and Fort Myers, FL; approximately 27-28 degrees N) extremes of the species distribution in North America Regardless of population origin, age-specific hazard rate increased with reproductive output and decreased with number of bloodmeals. Larger females took fewer bloodmeals, and they had greater hazard rates than did smaller females. There were no consistent differences between northern versus southern populations in resource allocation between reproduction and maintenance, reproduction over time, and reproductive investment among offspring, suggesting that latitudinal variation in climate is probably not a main selective factor impinging on adult mortality and reproductive schedules. One possible effect of climate on geographic differences in life history was detected. BL had lower survivorship, lower lifetime reproductive output, and lower adult reproductive rate than did all other populations. This result may be an indirect result of lower egg survivorship due to the severity of winter in BL compared with other populations, including VA at approximately the same latitude. Such a scenario may make the BL population more prone to extinction, irregularly recolonized from more favorable sites, and thus more susceptible to founder effects, genetic drift, and inbreeding, resulting in lower mean values of fitness-related traits.
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Affiliation(s)
- P T Leisnham
- Department of Biological Sciences, Behavior, Ecology, Evolution, and Systematics Section, Illinois State University, Normal, IL 61761-4120, USA.
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11
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Abstract
Inbreeding, which increases homozygosity throughout the genome by increasing the proportion of alleles that are identical by descent, is expected to compromise resistance against parasitism. Here, we demonstrate that host inbreeding increases susceptibility to ectoparasitism in a natural fruit fly (Drosophila nigrospiracula) - mite (Macrocheles subbadius) association, and that this effect depends on host genetic background. Moreover, flies generated from reciprocal crosses between susceptible inbred lines exhibited elevated levels of resistance similar to that in the mass-bred base population, confirming in reverse direction the causative link between expected heterozygosity and resistance. We also show that inbreeding reduces the host's ability to sustain energetically expensive behaviours, and that host exhaustion dramatically increases susceptibility. These findings suggest that inbreeding depression for resistance results from an inability to sustain defensive behaviours because of compromised physiological competence.
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Affiliation(s)
- L T Luong
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
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13
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Puurtinen M, Hytönen M, Knott KE, Taskinen J, Nissinen K, Kaitala V. The effects of mating system and genetic variability on susceptibility to trematode parasites in a freshwater snail, Lymnaea stagnalis. Evolution 2005; 58:2747-53. [PMID: 15696752 DOI: 10.1111/j.0014-3820.2004.tb01626.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The amount and distribution of genetic variability in host populations can have significant effects on the outcome of host-parasite interactions. We studied the effect of mating system and genetic variability on susceptibility of Lymnaea stagnalis snails to trematode parasites. Mating system of snails from eight populations differing in the amount of genetic variability was manipulated, and self- and cross-fertilized offspring were exposed to naturally occurring trematode parasites in a controlled lake experiment. Susceptibility of snails varied between populations, but mating-system treatment did not have a significant effect. Heterozygosity of snails was negatively correlated with the probability of trematode infection, however, suggesting that parasitic diseases may pose a serious threat to populations lacking genetic variability.
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Affiliation(s)
- Mikael Puurtinen
- Department of Biological and Environmental Science, PO Box 35, FI-40014 University of Jyväskylä, Finland.
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14
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Abstract
Evolutionary ecology seeks to understand the selective reasons for the design features of the immune defense, especially with respect to parasitism. The molecular processes thereby set limitations, such as the failure to recognize an antigen, response specificity, the cost of defense, and the risk of autoimmunity. Sex, resource availability, and interference by parasites also affect a response. In turn, the defense repertoire consists of different kinds of immune responses--constitutive or induced, general or specific--and involves memory and lasting protection. Because the situation often defies intuition, mathematical analysis is typically required to identify the costs and benefits of variation in design, but such studies are few. In all, insect immune defense is much more similar to that of vertebrates than previously thought. In addition, the field is now rapidly becoming revolutionized by molecular data and methods that allow unprecedented access to study evolution in action.
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Affiliation(s)
- Paul Schmid-Hempel
- Ecology and Evolution, ETH Zürich, ETH-Zentrum NW, CH-8092 Zürich, Switzerland.
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Haag CR, Sakwińska O, Ebert D. Test of synergistic interaction between infection and inbreeding in Daphnia magna. Evolution 2003; 57:777-83. [PMID: 12778547 DOI: 10.1111/j.0014-3820.2003.tb00289.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It has been proposed that parasitic infections increase selection against inbred genotypes. We tested this hypothesis experimentally using pairs of selfed and outcrossed sibling lines of the freshwater crustacean Daphnia magna, which can be maintained clonally. We studied the performance of selfed relative to outcrossed sibling clones during repeated pairwise clonal competition in the presence and absence of two species of microsporidian parasites. In 13 of the 14 pairs, the selfed clones did worse than the outcrossed ones in the control treatment, but the presence of either parasite did not result in an overall increase in this difference. Rather, it decreased the performance of the selfed relative to the outcrossed sibling in some pairs and increased it in others. Moreover, the two parasite species did not have the same effect in a given pair. This indicates that, contrary to the hypothesis that parasites generally lead to a decreased performance of inbred genotypes, their effect may depend on the genetic background of the host as well as on the parasite species, and suggests that inbreeding can lead to reduced or increased resistance to parasites. Our findings also indicate that there is variation for specific resistance to different species of parasites in the meta-population from which the hosts for this study were obtained.
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Affiliation(s)
- Christoph R Haag
- Université de Fribourg, Département de Biologie, Unité d'Ecologie et d'Evolution, Chemin du Musée 10, CH-1700 Fribourg, Switzerland.
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Carr DE, Murphy JF, Eubanks MD. The susceptibility and response of inbred and outbred Mimulus guttatus to infection by Cucumber mosaic virus. Evol Ecol 2003. [DOI: 10.1023/a:1022439432213] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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17
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Christen M, Kurtz J, Milinski M. Outcrossing increases infection success and competitive ability: experimental evidence from a hermaphrodite parasite. Evolution 2002; 56:2243-51. [PMID: 12487354 DOI: 10.1111/j.0014-3820.2002.tb00148.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The maintenance of two genetically distinct reproductive modes such as outcrossing and selfing within a population of animals or plants is still a matter of considerable debate. Hermaphroditic parasites often reproduce either alone by selfing or in pairs by outcrossing. They can be used as a model to study potential benefits of outcrossing. Any advantage from outcrossing may be important, especially in host-parasite coevolution, but has not, to our knowledge, been studied yet in any parasite species. We studied the potential effect of outcrossing in a tapeworm, Schistocephalus solidus, on both infection success and growth in its first intermediate host, the copepod Macrocyclops albidus. Tapeworms that had been obtained from natural populations of three-spined sticklebacks (Gasterosteus aculeatus) were allowed to reproduce either alone or in pairs, in an in vitro system that replaced the final host's gut. This resulted in either selfed or outcrossed offspring, respectively. In one part of the experiment, copepods were exposed to either selfed or outcrossed parasites, in a second part to both types simultaneously, in order to study the effect of competition between them. To discriminate parasites of either origin within the same host, a novel method for fluorescent vital labeling was used. We show here for the first time that outcrossed parasites had a higher infection success and faster development in the host. This advantage of outcrossing became apparent only in the competitive situation, in which superior abilities of parasites to extract limiting resources from the host become crucial.
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Affiliation(s)
- Mira Christen
- Department of Evolutionary Ecology, Max-Planck-Institute of Limnology, August-Thienemann-Strasse 2, 24306 Plön, Germany.
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Wiehn J, Kopp K, Rezzonico S, Karttunen S, Jokela J. Family-level covariation between parasite resistance and mating system in a hermaphroditic freshwater snail. Evolution 2002; 56:1454-61. [PMID: 12206245 DOI: 10.1111/j.0014-3820.2002.tb01457.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Genetic compatibility, nonspecific defenses, and environmental effects determine parasite resistance. Host mating system (selfing vs. outcrossing) should be important for parasite resistance because it determines the segregation of alleles at the resistance loci and because inbreeding depression may hamper immune defenses. Individuals of a mixed mating hermaphroditic freshwater snail, Lymnaea ovata, are commonly infected by a digenetic trematode parasite, Echinoparyphium recurvatum. We examined covariation between quantitative resistance to novel parasites and mating system by exposing snail families from four populations that differed by their inbreeding coefficients. We found that resistance was unrelated to inbreeding coefficient of the population, suggesting that the more inbred populations did not carry higher susceptibility load than the less inbred populations. Most of the variation in resistance was expressed among the families within the populations. In the population with the lowest inbreeding coefficient, resistance increased with outcrossing rate of the family, as predicted if selfing had led to inbreeding depression. In the other three populations with higher inbreeding coefficients, resistance was unrelated to outcrossing rate. The results suggest that in populations with higher inbreeding some of the genetic load has been purged, uncoupling the predicted relationship between outcrossing rate and resistance. Snail families also displayed crossing reaction norms for resistance when tested in two environments that presented low and high immune challenge, suggesting that genotype-by-environment interactions are important for parasite resistance.
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Affiliation(s)
- Jürgen Wiehn
- Initiative for Ecology and Evolution-Ecology and Evolution, ETH-Zürich, ETH-Zentrum NW, Switzerland.
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Hoang A. Immune response to parasitism reduces resistance of Drosophila melanogaster to desiccation and starvation. Evolution 2001; 55:2353-8. [PMID: 11794793 DOI: 10.1111/j.0014-3820.2001.tb00748.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In natural populations, organisms experience simultaneously biotic (e.g., competitors and parasites) and abiotic (e.g., temperature and humidity) stresses. Thus, species must have the capacity to respond to combinations of stressors. How does interaction between biotic and abiotic stress affect organismal performance? To address this question, I studied stress resistance of adult Drosophila melanogaster that survived parasitic attack (as larvae) by the parasitoid Asobara tabida. To determine the impact of genotype on stress resistance. I measured survival under desiccation and starvation of flies within isofemale (genetic) lines. Survivors of parasitism had slightly reduced survivorship compared to unparasitized relatives when both were unstressed, and this difference was exacerbated by desiccation and starvation. These results indicate multiple stressors can compound each other's individual negative effects on fitness. Moreover, isofemale lines differed in their sensitivity to environmental stress and to parasitism. Consequently, genotypic differences in sensitivity to stress may reflect differences in investment priorities between traits that promote survival over other life-history characters.
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Affiliation(s)
- A Hoang
- Department of Zoology, University of Washington, Seattle 98195-1800, USA.
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