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Caesar, Sofia
Publications (10 of 10) Show all publications
Johansson, J., Caesar, S. & Forsman, A. (2013). Multiple paternity increases phenotypic diversity in Tetrix subulata pygmy grasshoppers. Journal of Orthoptera Research, 22(2), 79-85
Open this publication in new window or tab >>Multiple paternity increases phenotypic diversity in Tetrix subulata pygmy grasshoppers
2013 (English)In: Journal of Orthoptera Research, ISSN 1082-6467, Vol. 22, no 2, p. 79-85Article in journal (Refereed) Published
Abstract [en]

Multiple paternity within clutches has been recorded among a variety of organisms. The degree of genetic similarity between parents may influence the number and viability of offspring. Females may therefore mate with several males as an insurance against sterile, low quality or genetically incompatible mates, but also to obtain half sibling offspring that are genetically and phenotypically more diverse. We examine the links between polyandry, multiple paternity and offspring phenotypic diversity in the color polymorphic pygmy grasshopper Tetrix subulata. By experimentally mating virgin females and genotyping the resulting offspring using microsatellite markers, we demonstrate that polyandrous females can produce offspring sired by different males. Analyses of microsatellite data and color patterns of captive reared families produced by wild caught females that were not mated in the laboratory, confirmed that multiple paternity occurs in the wild, and that it may increase color morph diversity among half-siblings. Polyandrous mating behavior may thus influence the evolutionary dynamics and maintenance of color polymorphism in this species.

National Category
Evolutionary Biology
Research subject
Ecology, Evolutionary Biology
Identifiers
urn:nbn:se:lnu:diva-31365 (URN)10.1665/034.022.0204 (DOI)2-s2.0-84891822078 (Scopus ID)
Available from: 2014-01-02 Created: 2014-01-02 Last updated: 2018-10-24Bibliographically approved
Forsman, A., Wennersten, L., Karlsson, M. & Caesar, S. (2012). Variation in founder groups promotes establishment success in the wild. Proceedings of the Royal Society of London. Biological Sciences, 279(1739), 2800-2806
Open this publication in new window or tab >>Variation in founder groups promotes establishment success in the wild
2012 (English)In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 279, no 1739, p. 2800-2806Article in journal (Refereed) Published
Abstract [en]

Environmental changes currently pose severe threats to biodiversity, and reintroductions and translocations are increasingly used to protect declining populations and species from extinction. Theory predicts that establishment success should be higher for more variable groups of dissimilar individuals. To test this ‘diversity promotes establishment’ hypothesis, we introduced colour polymorphic pygmy grasshoppers (Tetrix subulata) to different sites in the wild. The number of descendants found at the release sites the subsequent year increased with increasing number of colour morphs in the founder group, and variation in founder groups also positively affected colour morph diversity in the established populations. Since colour morphs differ in morphology, physiology, behaviour, reproductive life history and types of niche used, these findings demonstrate that variation among individuals in functionally important traits promotes establishment success under natural conditions, and further indicate that founder diversity may contribute to evolutionary rescue and increased population persistence.

National Category
Ecology Evolutionary Biology
Research subject
Natural Science, Evolutionary Biology
Identifiers
urn:nbn:se:lnu:diva-18040 (URN)10.1098/rspb.2012.0174 (DOI)2-s2.0-84862152496 (Scopus ID)
Available from: 2012-03-16 Created: 2012-03-16 Last updated: 2019-02-27Bibliographically approved
Caesar, S., Karlsson, M. & Forsman, A. (2010). Diversity and relatedness enhance survival in colour polymorphic grasshoppers. PLoS ONE, 5(5), Article ID e10880.
Open this publication in new window or tab >>Diversity and relatedness enhance survival in colour polymorphic grasshoppers
2010 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 5, no 5, article id e10880Article in journal (Refereed) Published
Abstract [en]

Evolutionary theory predicts that different resource utilization and behaviour by alternative phenotypes may reduce competition and enhance productivity and individual performance in polymorphic, as compared with monomorphic, groups of individuals. However, firm evidence that members of more heterogeneous groups benefit from enhanced survival has been scarce or lacking. Furthermore, benefits associated with phenotypic diversity may be counterbalanced by costs mediated by reduced relatedness, since closely related individuals typically are more similar. Pygmy grasshoppers (Tetrix subulata) are characterized by extensive polymorphism in colour pattern, morphology, behaviour and physiology. We studied experimental groups founded by different numbers of mothers and found that survival was higher in low than in high density, that survival peaked at intermediate colour morph diversity in high density, and that survival was independent of diversity in low density where competition was less intense. We further demonstrate that survival was enhanced by relatedness, as expected if antagonistic and competitive interactions are discriminately directed towards non-siblings. We therefore also performed behavioural observations and staged encounters which confirmed that individuals recognized and responded differently to siblings than to non-siblings. We conclude that negative effects associated with competition are less manifest in diverse groups, that there is conflicting selection for and against genetic diversity occurring simultaneously, and that diversity and relatedness may facilitate the productivity and ecological success of groups of interacting individuals.

National Category
Biological Sciences Ecology
Research subject
Ecology, Evolutionary Biology
Identifiers
urn:nbn:se:lnu:diva-6046 (URN)10.1371/journal.pone.0010880 (DOI)2-s2.0-77956542364 (Scopus ID)
Available from: 2010-06-11 Created: 2010-06-11 Last updated: 2017-12-12Bibliographically approved
Caesar, S. & Forsman, A. (2009). Do polyandrous pygmy grasshopper females obtain fitness benefits for their offspring?. Behavioral Ecology, 20(2), 354-361
Open this publication in new window or tab >>Do polyandrous pygmy grasshopper females obtain fitness benefits for their offspring?
2009 (English)In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 20, no 2, p. 354-361Article in journal (Refereed) Published
Abstract [en]

Explanations for polyandry in insects invoke material and genetic benefits that enhance female fitness via the production of more viable or more variable offspring. Here we use the color polymorphic pygmy grasshopper, Tetrix subulata, to evaluate effects of male quality, mate color morph resemblance (a proxy for compatibility), and polyandry on offspring performance. We experimentally mated females with different numbers and color morph combinations of males and reared offspring under either sun-exposed or shaded conditions using a split-brood design. We find a significant male identity effect on egg hatchability, consistent with the hypothesis that males vary in paternal quality. Offspring viability posthatching varied in a complex manner with solar regime, mating treatment, and parental resemblance. The effects of parental color morph resemblance on offspring performance suggest a potential role of compatibility and offspring variability. Monandrous females produced more viable offspring than polyandrous females (under shaded conditions) and we suggest as a hypothesis that the expected positive influence of polyandry on offspring performance may have been outweighed by more intense competition and antagonistic interactions among half-siblings. That an effect of mating treatment was evident under shaded but not under sun-exposed conditions suggests that great care is called for when making inferences from studies that show negative results.

National Category
Evolutionary Biology
Research subject
Natural Science, Evolutionary Biology
Identifiers
urn:nbn:se:lnu:diva-1943 (URN)10.1093/beheco/arn153 (DOI)
Available from: 2010-04-06 Created: 2010-04-06 Last updated: 2017-12-12Bibliographically approved
Karlsson, M., Johansson, J., Caesar, S. & Forsman, A. (2009). No evidence for developmental plasticity of colour patterns in response to rearing substrate in pygmy grasshoppers. Canadian Journal of Zoology, 87(11), 1044-1051
Open this publication in new window or tab >>No evidence for developmental plasticity of colour patterns in response to rearing substrate in pygmy grasshoppers
2009 (English)In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 87, no 11, p. 1044-1051Article in journal (Refereed) Published
Abstract [en]

Color polymorphisms in animals may result from genetic polymorphisms, developmental plasticity, or a combination where some phenotypic components are under strong genetic control and other aspects are influenced by developmental plasticity. Understanding how color polymorphisms evolve demands knowledge of how genetic and epigenetic environmental cues influence the development and phenotypic expression of organisms. Pygmy grasshoppers (Orthoptera, Tetrigidae) vary in color pattern within and among populations. Color morphs differ in morphology, behavior, and life history, suggesting that they represent alternative ecological strategies. Pygmy grasshoppers also show fire melanism, a rapid increase in the frequency of black and dark-colored phenotypes in populations inhabiting fire-ravaged areas. We examined the influence of plasticity on color polymorphism in the pygmy grasshopper Tetrix subulata (L., 1761) using a split-brood design. Individuals were experimentally raised in solitude on either crushed charcoal or white aquarium gravel. Our analyses uncovered no plasticity of either color pattern or overall darkness of coloration in response to rearing substrate. Instead, we find a strong resemblance between maternal and offspring color patterns. We conclude that pygmy grasshopper color morphs are strongly influenced by genetic cues or maternal effects, and that there is no evidence for developmental plasticity of coloration in response to rearing conditions in these insects.

National Category
Biological Sciences
Research subject
Natural Science, Evolutionary Biology
Identifiers
urn:nbn:se:hik:diva-2447 (URN)10.1139/Z09-097 (DOI)
Available from: 2010-01-20 Created: 2010-01-20 Last updated: 2017-12-12Bibliographically approved
Forsman, A., Ahnesjö, J., Caesar, S. & Karlsson, M. (2008). A model of ecological and evolutionary consequences of color polymorphism. Ecology, 89, 34-40
Open this publication in new window or tab >>A model of ecological and evolutionary consequences of color polymorphism
2008 (English)In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 89, p. 34-40Article in journal (Refereed) Published
National Category
Natural Sciences
Research subject
Natural Science; Natural Science, Evolutionary Biology
Identifiers
urn:nbn:se:lnu:diva-1612 (URN)
Available from: 2010-04-06 Created: 2010-04-06 Last updated: 2017-12-12Bibliographically approved
Karlsson, M., Caesar, S., Forsman, A. & Ahnesjö, J. (2008). Dynamics of colour polymorphism in a changing environment: Fire melanism and then what?. Oecologia, 154(4), 715-724
Open this publication in new window or tab >>Dynamics of colour polymorphism in a changing environment: Fire melanism and then what?
2008 (English)In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 154, no 4, p. 715-724Article in journal (Refereed) Published
National Category
Biological Sciences
Research subject
Natural Science, Evolutionary Biology
Identifiers
urn:nbn:se:hik:diva-2445 (URN)
Available from: 2010-01-22 Created: 2010-01-20 Last updated: 2017-12-12Bibliographically approved
Forsman, A., Ahnesjö, J. & Caesar, S. (2007). Fitness benefits of diverse offspring in pygmy grasshoppers. Evolutionary Ecology Research, 9(8), 1305-1318
Open this publication in new window or tab >>Fitness benefits of diverse offspring in pygmy grasshoppers
2007 (English)In: Evolutionary Ecology Research, Vol. 9, no 8, p. 1305-1318Article in journal (Refereed) Published
Abstract [en]

Question: Do females obtain fitness benefits from an increase in offspring diversity?Hypotheses: Polyandry increases offspring diversity within a clutch. Increased offspring diversity will reduce competition among siblings (manifested as increased mean survival in more diverse families) and the probability that all offspring might be ill-suited to future conditions (manifested as lower variance in survival in diverse families).Organisms: Pygmy grasshoppers, Tetrix subulata and Tetrix: undulata, that are polymorphic for colour pattern.Field site: South-central Sweden.Methods: We varied the number of mates provided to colour polymorphic pygmy grasshoppers. We reared families in either warm or cold conditions using a split-brood design.Conclusions: The colour morph diversity of broods increased with the number of experimentally provided mates. Colour morphs represent alternative strategies that differ in body size, physiology, behaviour, and life history. Survival increased with increasing sibling diversity, supporting the hypothesis that different morphs avoid competition by using different subsets of available resources. Homogeneous families (in which all siblings belong to the same or only a few colour morphs) varied more in survival than did families with diverse siblings, supporting the hypothesis that morphs vary in their ability to cope with and utilize different resources.

National Category
Developmental Biology
Research subject
Natural Science; Natural Science, Evolutionary Biology
Identifiers
urn:nbn:se:lnu:diva-2329 (URN)
Available from: 2010-04-07 Created: 2010-04-07 Last updated: 2017-01-16Bibliographically approved
Caesar, S., Ahnesjö, J. & Forsman, A. (2007). Testing the role of co-adapted genes versus bet hedging for mating strategies in colour polymorphic pygmy grasshoppers. Biological Journal of the Linnean Society, 90, 491-499
Open this publication in new window or tab >>Testing the role of co-adapted genes versus bet hedging for mating strategies in colour polymorphic pygmy grasshoppers
2007 (English)In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 90, p. 491-499Article in journal (Refereed) Published
National Category
Natural Sciences
Research subject
Natural Science, Evolutionary Biology
Identifiers
urn:nbn:se:lnu:diva-2265 (URN)10.1111/j.1095-8312.2007.00739.x (DOI)
Available from: 2010-04-07 Created: 2010-04-07 Last updated: 2017-12-12Bibliographically approved
Karlsson, M., Wennersten, L., Johansson, J., Caesar, S., Lapid, E. & Forsman, A.Rapid parallel evolution of fire melanism in pygmy grasshoppers..
Open this publication in new window or tab >>Rapid parallel evolution of fire melanism in pygmy grasshoppers.
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(English)Manuscript (preprint) (Other academic)
National Category
Biological Sciences
Research subject
Natural Science, Evolutionary Biology
Identifiers
urn:nbn:se:hik:diva-2454 (URN)
Available from: 2010-01-22 Created: 2010-01-20 Last updated: 2019-02-27Bibliographically approved
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