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Tseng ZJ, Terhune CE. Sexual Dimorphism and Divergent Evolutionary Pathways in Primate Cranial Biomechanics: Insights From a Theoretical Morphology Framework. J Morphol 2024; 285:e21780. [PMID: 39385398 DOI: 10.1002/jmor.21780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2024] [Revised: 09/20/2024] [Accepted: 09/25/2024] [Indexed: 10/12/2024]
Abstract
The mammalian order Primates is known for widespread sexual dimorphism in size and phenotype. Despite repeated speculation that primate sexual size dimorphism either facilitates or is in part driven by functional differences in how males and females interact with their environments, few studies have directly assessed the influence of sexual dimorphism on performance traits. Here, we use a theoretical morphology framework to show that sexual dimorphism in primate crania is associated with divergent biomechanical performance traits. The degree of dimorphism is a significant covariate in biomechanical trait divergence between sexes. Males exhibit less efficient but stiffer cranial shapes and significant evolutionary allometry in biomechanical performance, whereas females maintain performance stability across their size spectrum. Evolutionary rates are elevated for efficiency in females whereas males emphasize size-dependent cranial stiffness. These findings support a hypothesis of sex-linked bifurcation in masticatory system performance: larger male crania and faster size evolution partially compensate for low efficiency and reflect a de-emphasis of mechanical leverage, whereas female crania maintain higher mechanical efficiency overall and evolve more rapidly in molar-based masticatory performance. The evolutionary checks-and-balances between size dimorphism and cranial mechanical performance may be a more important driver of primate phenotypic evolution than has been hitherto appreciated.
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Affiliation(s)
- Z Jack Tseng
- Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, California, USA
| | - Claire E Terhune
- Department of Anthropology, University of Arkansas, Fayetteville, Arkansas, USA
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2
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Moyaho A, Salazar-Bautista JL, Beristain-Castillo E, Amira FU. Iridescent scales signal male fighting ability to access females in the jewelled splitfin Xenotoca variata. JOURNAL OF FISH BIOLOGY 2023; 102:794-802. [PMID: 36648014 DOI: 10.1111/jfb.15316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 01/10/2023] [Indexed: 06/17/2023]
Abstract
Jewelled splitfin males (Xenotoca variata) possess multi-colour iridescent scales (speckles) on the flanks. This study tested the hypothesis that the number of speckles could be a good proxy for predicting fighting ability in contests for access to females. The experiments consisted in observing and recording males' agonistic behaviour, courtship displays and mating attempts in mixed-sex groups. The data were analysed and presented based on a Bayesian approach, which revealed that the density (cm-2 ) of speckles was positively correlated with the increase observed in the proportional frequency of attacks. Similarly, the density of speckles was positively associated with the increase observed in the frequency of courtship behaviour and with the frequency of mating attempts. Male-male aggressions drastically diminished (by eightfold) when females were removed from the observation tanks. These results indicate that the number of speckles is a consistent predictor of successful access to females and therefore, speckled males are likely to be able to gain more mating opportunities. This finding highlights the ubiquitous role iridescent colours play in visual signalling.
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Affiliation(s)
- Alejandro Moyaho
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, Puebla, Mexico
| | - José Luis Salazar-Bautista
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, Puebla, Mexico
| | | | - Flores-Urbina Amira
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, Puebla, Mexico
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3
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Anand PP, Seena S, Girish Kumar P, Shibu Vardhanan Y. Species morphospace boundary revisited through wing phenotypic variations of Antodynerus species (Hymenoptera: Vespidae: Eumeninae) from the Indian subcontinent. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2022.965577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The main objective of this study was to investigate the taxonomic significance of wing phenotypic variations (size and shape) for classifying potter wasps. This is the first study investigating the wing size and shape variations, as well as wing asymmetry, sexual dimorphism, wing integration, and phylogenetic signal analysis of all known Antodynerus species from the Indian subcontinent: A. flavescens, A. limbatus, and A. punctatipennis. We used forewings and hindwings for geometric morphometric analysis, and we proved that each species’ wing had unique size and shape variations, as well as significant right–left wing asymmetry and sexual dimorphism across the Antodynerus species, as verified by discriminant function analysis. Wings of Vespidae are longitudinally folded; based on that, we tested two alternative wing modular hypotheses for evaluating the wing integration, using two subsets organization, such as anterior–posterior (AP) and proximal-distal (PD) wing modular organization. We proved that Antodynerus species wings are highly integrated units (RV > 0.5), and we rejected our hypothesis at p < 0.05. The morphospace distribution analysis revealed that each species has its unique morphospace boundary, although they share some level of homoplasy, which suggests to us that we can use wing morphometric traits for Antodynerus species delimitation. In addition, we revealed the phylogenetic signal of Antodynerus species. Surprisingly, we found a shape-related phylogenetic signal in the forewing, and there is no significant (p > 0.05) phylogenetic signal in forewing size, hindwing shape, and size. We observed that the Antodynerus species’ forewing shape is evolutionarily more highly constrained than the hindwing. We found that A. limbatus and A. flavescens with distinct geographical distribution share a similar evolutionary history, while A. punctatipennis evolved independently.
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Kyrgiafini MA, Giannoulis T, Moutou KA, Mamuris Z. Investigating the Impact of a Curse: Diseases, Population Isolation, Evolution and the Mother's Curse. Genes (Basel) 2022; 13:2151. [PMID: 36421825 PMCID: PMC9690142 DOI: 10.3390/genes13112151] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/13/2022] [Accepted: 11/15/2022] [Indexed: 09/08/2024] Open
Abstract
The mitochondrion was characterized for years as the energy factory of the cell, but now its role in many more cellular processes is recognized. The mitochondrion and mitochondrial DNA (mtDNA) also possess a set of distinct properties, including maternal inheritance, that creates the Mother's Curse phenomenon. As mtDNA is inherited from females to all offspring, mutations that are harmful to males tend to accumulate more easily. The Mother's Curse is associated with various diseases, and has a significant effect on males, in many cases even affecting their reproductive ability. Sometimes, it even leads to reproductive isolation, as in crosses between different populations, the mitochondrial genome cannot cooperate effectively with the nuclear one resulting in a mito-nuclear incompatibility and reduce the fitness of the hybrids. This phenomenon is observed both in the laboratory and in natural populations, and have the potential to influence their evolution and speciation. Therefore, it turns out that the study of mitochondria is an exciting field that finds many applications, including pest control, and it can shed light on the molecular mechanism of several diseases, improving successful diagnosis and therapeutics. Finally, mito-nuclear co-adaptation, paternal leakage, and kin selection are some mechanisms that can mitigate the impact of the Mother's Curse.
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Affiliation(s)
- Maria-Anna Kyrgiafini
- Laboratory of Genetics, Comparative and Evolutionary Biology, Department of Biochemistry and Biotechnology, University of Thessaly, Viopolis, Mezourlo, 41500 Larissa, Greece
| | - Themistoklis Giannoulis
- Laboratory of Biology, Genetics and Bioinformatics, Department of Animal Sciences, University of Thessaly, Gaiopolis, 41336 Larissa, Greece
| | - Katerina A. Moutou
- Laboratory of Genetics, Comparative and Evolutionary Biology, Department of Biochemistry and Biotechnology, University of Thessaly, Viopolis, Mezourlo, 41500 Larissa, Greece
| | - Zissis Mamuris
- Laboratory of Genetics, Comparative and Evolutionary Biology, Department of Biochemistry and Biotechnology, University of Thessaly, Viopolis, Mezourlo, 41500 Larissa, Greece
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Cullen DA, Sword GA, Rosenthal GG, Simpson SJ, Dekempeneer E, Hertog MLATM, Nicolaï BM, Caes R, Mannaerts L, Vanden Broeck J. Sexual repurposing of juvenile aposematism in locusts. Proc Natl Acad Sci U S A 2022; 119:e2200759119. [PMID: 35969777 PMCID: PMC9407653 DOI: 10.1073/pnas.2200759119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 06/09/2022] [Indexed: 11/18/2022] Open
Abstract
Adaptive plasticity requires an integrated suite of functional responses to environmental variation, which can include social communication across life stages. Desert locusts (Schistocerca gregaria) exhibit an extreme example of phenotypic plasticity called phase polyphenism, in which a suite of behavioral and morphological traits differ according to local population density. Male and female juveniles developing at low population densities exhibit green- or sand-colored background-matching camouflage, while at high densities they show contrasting yellow and black aposematic patterning that deters predators. The predominant background colors of these phenotypes (green/sand/yellow) all depend on expression of the carotenoid-binding "Yellow Protein" (YP). Gregarious (high-density) adults of both sexes are initially pinkish, before a YP-mediated yellowing reoccurs upon sexual maturation. Yellow color is especially prominent in gregarious males, but the reason for this difference has been unknown since phase polyphenism was first described in 1921. Here, we use RNA interference to show that gregarious male yellowing acts as an intrasexual warning signal, which forms a multimodal signal with the antiaphrodisiac pheromone phenylacetonitrile (PAN) to prevent mistaken sexual harassment from other males during scramble mating in a swarm. Socially mediated reexpression of YP thus adaptively repurposes a juvenile signal that deters predators into an adult signal that deters undesirable mates. These findings reveal a previously underappreciated sexual dimension to locust phase polyphenism, and promote locusts as a model for investigating the relative contributions of natural versus sexual selection in the evolution of phenotypic plasticity.
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Affiliation(s)
- Darron A Cullen
- Department of Biology, KU Leuven (University of Leuven), 3000 Leuven, Belgium
| | - Gregory A Sword
- Department of Entomology, Texas A&M University, College Station, TX 77843
| | - Gil G Rosenthal
- Department of Biology, Università degli Studi di Padova, 35131 Padova, Italy
| | - Stephen J Simpson
- Charles Perkins Centre, University of Sydney, Sydney, NSW, 2006, Australia
- School of Life Sciences, University of Sydney, Sydney, NSW, 2006, Australia
| | - Elfie Dekempeneer
- Department of Biosystems, KU Leuven (University of Leuven), 3001 Leuven, Belgium
| | | | - Bart M Nicolaï
- Department of Biosystems, KU Leuven (University of Leuven), 3001 Leuven, Belgium
| | - Robbe Caes
- Department of Biology, KU Leuven (University of Leuven), 3000 Leuven, Belgium
| | - Lisa Mannaerts
- Department of Biology, KU Leuven (University of Leuven), 3000 Leuven, Belgium
| | - Jozef Vanden Broeck
- Department of Biology, KU Leuven (University of Leuven), 3000 Leuven, Belgium
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Revathi Venkateswaran V, Roth O, Gokhale CS. Consequences of combining sex-specific traits. Evolution 2021; 75:1274-1287. [PMID: 33759452 DOI: 10.1111/evo.14204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 02/12/2021] [Indexed: 12/22/2022]
Abstract
Males and females follow distinct life-history strategies that have co-evolved with several sex-specific traits. Higher investment into parental investment (PI) demands an increased lifespan. Thus, resource allocation toward an efficient immune system is mandatory. In contrast, resources allocated toward secondary sexual signals (ornamentation) may negatively correlate with investment into immunity and ultimately result in a shorter lifespan. Previous studies have addressed how resource allocation toward single sex-specific traits impacts lifetime reproductive success (LRS). However, the trade-offs between diverse sex-specific characteristics and their impact on LRS remain largely unassessed impeding our understanding of life-history evolution. We have designed a theoretical framework (informed by experimental data and evolutionary genetics) that explores the effects of multiple sex-specific traits and assessed how they influence LRS. From the individual sex-specific traits, we inferred the consequences at the population level by evaluating adult sex ratios (ASR). Our theory implies that sex-specific resource allocation toward the assessed traits resulted in a biased ASR. Our model focuses on the impact of PI, ornamentation, and immunity as causal to biased ASR. The framework developed herein can be employed to understand the combined impact of diverse sex-specific traits on the LRS and the eventual population dynamics of particular model systems.
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Affiliation(s)
- Vandana Revathi Venkateswaran
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, August Thienemann Str. 2, Plön, 24306, Germany
| | - Olivia Roth
- GEOMAR - Helmholtz Center for Ocean Research, Düsternbrookerweg 20, Kiel, D-24105, Germany
| | - Chaitanya S Gokhale
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, August Thienemann Str. 2, Plön, 24306, Germany
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Spanke T, Hilgers L, Wipfler B, Flury JM, Nolte AW, Utama IV, Misof B, Herder F, Schwarzer J. Complex sexually dimorphic traits shape the parallel evolution of a novel reproductive strategy in Sulawesi ricefishes (Adrianichthyidae). BMC Ecol Evol 2021; 21:57. [PMID: 33879056 PMCID: PMC8056572 DOI: 10.1186/s12862-021-01791-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 04/09/2021] [Indexed: 11/24/2022] Open
Abstract
Background Pelvic brooding is a form of uni-parental care, and likely evolved in parallel in two lineages of Sulawesi ricefishes. Contrary to all other ricefishes, females of pelvic brooding species do not deposit eggs at a substrate (transfer brooding), but carry them until the fry hatches. We assume that modifications reducing the costs of egg carrying are beneficial for pelvic brooding females, but likely disadvantageous in conspecific males, which might be resolved by the evolution of sexual dimorphism via sexual antagonistic selection. Thus we hypothesize that the evolution of pelvic brooding gave rise to female-specific skeletal adaptations that are shared by both pelvic brooding lineages, but are absent in conspecific males and transfer brooding species. To tackle this, we combine 3D-imaging and morphometrics to analyze skeletal adaptations to pelvic brooding. Results The morphology of skeletal traits correlated with sex and brooding strategy across seven ricefish species. Pelvic brooding females have short ribs caudal of the pelvic girdle forming a ventral concavity and clearly elongated and thickened pelvic fins compared to both sexes of transfer brooding species. The ventral concavity limits the body cavity volume in female pelvic brooders. Thus body volumes are smaller compared to males in pelvic brooding species, a pattern sharply contrasted by transfer brooding species. Conclusions We showed in a comparative framework that highly similar, sexually dimorphic traits evolved in parallel in both lineages of pelvic brooding ricefish species. Key traits, present in all pelvic brooding females, were absent or much less pronounced in conspecific males and both sexes of transfer brooding species, indicating that they are non-beneficial or even maladaptive for ricefishes not providing extended care. We assume that the combination of ventral concavity and robust, elongated fins reduces drag of brooding females and provides protection and stability to the egg cluster. Thus ricefishes are one of the rare examples where environmental factors rather than sexual selection shaped the evolution of sexually dimorphic skeletal adaptations. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-021-01791-z.
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Affiliation(s)
- Tobias Spanke
- Zoologisches Forschungsmuseum Alexander Koenig, Adenauerallee 160, 53113, Bonn, Germany
| | - Leon Hilgers
- Zoologisches Forschungsmuseum Alexander Koenig, Adenauerallee 160, 53113, Bonn, Germany
| | - Benjamin Wipfler
- Zoologisches Forschungsmuseum Alexander Koenig, Adenauerallee 160, 53113, Bonn, Germany
| | - Jana M Flury
- Zoologisches Forschungsmuseum Alexander Koenig, Adenauerallee 160, 53113, Bonn, Germany
| | - Arne W Nolte
- Carl Von Ossietzky Universität Oldenburg, AG Ökologische Genomik, Carl von Ossietzky-Str. 9-11, 26111, Oldenburg, Germany
| | - Ilham V Utama
- Ichthyology Laboratory, Indonesian Institute of Sciences (LIPI), JL. Raya Jakarta-Bogor Km. 46, Cibinong, 16911, Indonesia
| | - Bernhard Misof
- Zoologisches Forschungsmuseum Alexander Koenig, Adenauerallee 160, 53113, Bonn, Germany
| | - Fabian Herder
- Zoologisches Forschungsmuseum Alexander Koenig, Adenauerallee 160, 53113, Bonn, Germany
| | - Julia Schwarzer
- Zoologisches Forschungsmuseum Alexander Koenig, Adenauerallee 160, 53113, Bonn, Germany.
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8
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Tolentino M, Anciães M. Display above courts of White‐throated manakins: A new view about its display behavior. Ethology 2020. [DOI: 10.1111/eth.13027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mariana Tolentino
- Programa de Pós‐Graduação em Ecologia Instituto Nacional de Pesquisas da Amazônia Manaus Brazil
- Laboratório de Biologia Evolutiva e Comportamento Animal Coordenação de Biodiversidade Instituto Nacional de Pesquisas da Amazônia Manaus Brazil
| | - Marina Anciães
- Laboratório de Biologia Evolutiva e Comportamento Animal Coordenação de Biodiversidade Instituto Nacional de Pesquisas da Amazônia Manaus Brazil
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9
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Wiens JJ, Tuschhoff E. Songs versus colours versus horns: what explains the diversity of sexually selected traits? Biol Rev Camb Philos Soc 2020; 95:847-864. [PMID: 32092241 DOI: 10.1111/brv.12593] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 01/25/2020] [Accepted: 02/10/2020] [Indexed: 01/14/2023]
Abstract
Papers on sexual selection often highlight the incredible diversity of sexually selected traits across animals. Yet, few studies have tried to explain why this diversity evolved. Animals use many different types of traits to attract mates and outcompete rivals, including colours, songs, and horns, but it remains unclear why, for example, some taxa have songs, others have colours, and others horns. Here, we first conduct a systematic survey of the basic diversity and distribution of different types of sexually selected signals and weapons across the animal Tree of Life. Based on this survey, we describe seven major patterns in trait diversity and distributions. We then discuss 10 unanswered questions raised by these patterns, and how they might be addressed. One major pattern is that most types of sexually selected signals and weapons are apparently absent from most animal phyla (88%), in contrast to the conventional wisdom that a diversity of sexually selected traits is present across animals. Furthermore, most trait diversity is clustered in Arthropoda and Chordata, but only within certain clades. Within these clades, many different types of traits have evolved, and many types appear to have evolved repeatedly. By contrast, other major arthropod and chordate clades appear to lack all or most trait types, and similar patterns are repeated at smaller phylogenetic scales (e.g. within insects). Although most research on sexual selection focuses on female choice, we find similar numbers of traits (among sampled species) are involved in male contests (44%) and female choice (55%). Overall, these patterns are largely unexplained and unexplored, as are many other fundamental questions about the evolution of these traits. We suggest that understanding the diversity of sexually selected traits may require a shift towards macroevolutionary studies at relatively deep timescales (e.g. tens to hundreds of millions of years ago).
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Affiliation(s)
- John J Wiens
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
| | - E Tuschhoff
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
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Kimock CM, Dubuc C, Brent LJN, Higham JP. Male morphological traits are heritable but do not predict reproductive success in a sexually-dimorphic primate. Sci Rep 2019; 9:19794. [PMID: 31874959 PMCID: PMC6930303 DOI: 10.1038/s41598-019-52633-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 10/18/2019] [Indexed: 11/25/2022] Open
Abstract
Sexual selection favours traits that increase reproductive success via increased competitive ability, attractiveness, or both. Male rhesus macaque (Macaca mulatta) morphological traits are likely to reflect the effects of multiple sexual selection pressures. Here, we use a quantitative genetic approach to investigate the production and maintenance of variation in male rhesus macaque morphometric traits which may be subject to sexual selection. We collected measurements of body size, canine length, and fat, from 125 male and 21 female free-ranging rhesus macaques on Cayo Santiago. We also collected testis volumes from males. We used a genetic pedigree to calculate trait heritability, to investigate potential trait trade-offs, and to estimate selection gradients. We found that variation in most male morphometric traits was heritable, but found no evidence of trait trade-offs nor that traits predicted reproductive success. Our results suggest that male rhesus macaque morphometric traits are either not under selection, or are under mechanisms of sexual selection that we could not test (e.g. balancing selection). In species subject to complex interacting mechanisms of selection, measures of body size, weaponry, and testis volume may not increase reproductive success via easily-testable mechanisms such as linear directional selection.
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Affiliation(s)
- Clare M Kimock
- Center for the Study of Human Origins, Department of Anthropology, New York University, New York, NY, USA.
| | - Constance Dubuc
- Center for the Study of Human Origins, Department of Anthropology, New York University, New York, NY, USA
| | - Lauren J N Brent
- Center for Research in Animal Behaviour, University of Exeter, Exeter, UK
| | - James P Higham
- Center for the Study of Human Origins, Department of Anthropology, New York University, New York, NY, USA
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11
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Abrahão VP, Pastana M, Marinho M. On a remarkable sexual dimorphic trait in the Characiformes related to the olfactory organ and description of a new miniature species of Tyttobrycon Géry (Characiformes: Characidae). PLoS One 2019; 14:e0226130. [PMID: 31851726 PMCID: PMC6919584 DOI: 10.1371/journal.pone.0226130] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 11/19/2019] [Indexed: 11/19/2022] Open
Abstract
Among the order Characiformes, secondary sexual dimorphism is commonly associated to the occurrence of bony hooks on fins, shape and length of the dorsal and anal fins, and sexual dichromatism. The analysis of a new miniature Characidae species of the genus Tyttobrycon, described herein, yielded to the discovery of a sexually dimorphic trait related to nostril aperture and number of olfactory lamellae. In this type of dimorphism, mature males present larger nostril aperture and higher number of olfactory lamella than females. A dimorphic olfactory organ is for the first time recorded and described for a member of the Characiformes. Gross morphology and development of brain and peripheral olfactory organ of Tyttobrycon sp. n. are described and compared to other species of Characidae. It is hypothesized that such dimorphic trait is related to male-male detection during cohort competition in small characids. The new species of Tyttobrycon is diagnosed from its congeners by the number of branched anal-fin rays (19-21) and the absence of a caudal-peduncle blotch. It occurs in a small tributary of Rio Madeira basin, near to the limit between Brazil and Bolivia, Acre State, Brazil.
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Affiliation(s)
- Vitor Pimenta Abrahão
- Museu de Zoologia da Universidade de São Paulo, São Paulo, SP, Brazil
- Programa de Pós-Graduação em Biodiversidade e Evolução, Instituto de Biologia, Universidade Federal da Bahia, Rua Barão de Geremoabo, Ondina, Salvador, BA, Brazil
| | - Murilo Pastana
- Museu de Zoologia da Universidade de São Paulo, São Paulo, SP, Brazil
| | - Manoela Marinho
- Museu de Zoologia da Universidade de São Paulo, São Paulo, SP, Brazil
- Laboratório de Sistemática e Morfologia de Peixes, Departamento de Sistemática e Ecologia/CCEN, Universidade Federal da Paraíba, Campus I, João Pessoa, PB, Brazil
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12
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Rodríguez-Escobar FE, Carrillo-Muñoz AI, Serrano-Meneses MA. Seasonal variation in the allometry of wing pigmentation in adult males of the territorial damselfly Hetaerina vulnerata (Insecta Odonata). ETHOL ECOL EVOL 2019. [DOI: 10.1080/03949370.2019.1693432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Frida E. Rodríguez-Escobar
- Departamento de Ciencias Químico-Biológicas, Universidad de las Américas Puebla, Puebla, C.P. 72810, México
| | - Aldo I. Carrillo-Muñoz
- Centro Tlaxcala de Biología de la Conducta, Universidad Autónoma de Tlaxcala, Carretera Tlaxcala-Puebla km 1.5, Tlaxcala, C.P. 90070, México
- Doctorado en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, Tlaxcala, México
| | - Martín A. Serrano-Meneses
- Departamento de Ciencias Químico-Biológicas, Universidad de las Américas Puebla, Puebla, C.P. 72810, México
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13
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Sexual Dimorphism and Foraging Trips of the Laysan Albatross ( Phoebastria immutabilis) on Guadalupe Island. Animals (Basel) 2019; 9:ani9060364. [PMID: 31212935 PMCID: PMC6617548 DOI: 10.3390/ani9060364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/20/2019] [Accepted: 05/28/2019] [Indexed: 11/17/2022] Open
Abstract
Simple Summary We evaluated the existence of sexual dimorphism in Laysan albatross from Guadalupe Island. Males were larger than females across all the morphological variables analyzed. We created a sex predictor model for Laysan albatross individuals that requires a minimum number of input variables and will considerably reduce the handling times and field costs of future studies. Laysan albatross foraging trips were recorded during their breeding season over multiple years and no significant differences were found between the distances travelled by males versus females. Abstract Sexual dimorphism in the Laysan albatross (Phoebastria immutabilis) on Guadalupe Island was evaluated during the breeding seasons of 2015–2018 by measuring and comparing 10 morphological attributes: cranial length, bill length, nostril length, cranial width, bill height, bill width, tarsus length, closed wing length, opened wing length, and wingspan length in reproductive adults (n = 135). Males were larger than females across all traits (Student’s t-test, p < 0.05, p < 0.05). We created a logistic model using stepwise regression to predict sex based on morphological variables. This model indicated four significant morphological predictor variables (z < 0.05) and was able to successfully predict the sex of P. immutabilis individuals in more than 90% of the cases. Based on these predictor variables, a web app was developed to determine the sex of the Laysan albatross in the field, providing a non-invasive method for rapid data collection that reduces costs and handling times while improving conservation efforts. We tracked Laysan albatross (n = 36) during breeding seasons and found no significant differences between females and males for either trip length (GLMM, F = 0.017, DF = 1, 1, p = 0.917 > 0.05) or maximum trip distance (GLMM, F = 0.374, DF = 1, 1, p = 0.651 > 0.05). Our results suggest that both sexes show a strong preference to travel to highly productive coastal waters northeast of the breeding colony that are influenced by the California Current. The present research will serve to establish a baseline to protect this species on Guadalupe Island and highlights the importance of understanding sexual dimorphism in at-risk seabird species.
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Rico-Guevara A, Hurme KJ. Intrasexually selected weapons. Biol Rev Camb Philos Soc 2019; 94:60-101. [PMID: 29924496 DOI: 10.1111/brv.12436] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 05/14/2018] [Accepted: 05/18/2018] [Indexed: 01/24/2023]
Abstract
We propose a practical concept that distinguishes the particular kind of weaponry that has evolved to be used in combat between individuals of the same species and sex, which we term intrasexually selected weapons (ISWs). We present a treatise of ISWs in nature, aiming to understand their distinction and evolution from other secondary sex traits, including from 'sexually selected weapons', and from sexually dimorphic and monomorphic weaponry. We focus on the subset of secondary sex traits that are the result of same-sex combat, defined here as ISWs, provide not previously reported evolutionary patterns, and offer hypotheses to answer questions such as: why have only some species evolved weapons to fight for the opposite sex or breeding resources? We examined traits that seem to have evolved as ISWs in the entire animal phylogeny, restricting the classification of ISW to traits that are only present or enlarged in adults of one of the sexes, and are used as weapons during intrasexual fights. Because of the absence of behavioural data and, in many cases, lack of sexually discriminated series from juveniles to adults, we exclude the fossil record from this review. We merge morphological, ontogenetic, and behavioural information, and for the first time thoroughly review the tree of life to identify separate evolution of ISWs. We found that ISWs are only found in bilateral animals, appearing independently in nematodes, various groups of arthropods, and vertebrates. Our review sets a reference point to explore other taxa that we identify with potential ISWs for which behavioural or morphological studies are warranted. We establish that most ISWs come in pairs, are located in or near the head, are endo- or exoskeletal modifications, are overdeveloped structures compared with those found in females, are modified feeding structures and/or locomotor appendages, are most common in terrestrial taxa, are frequently used to guard females, territories, or both, and are also used in signalling displays to deter rivals and/or attract females. We also found that most taxa lack ISWs, that females of only a few species possess better-developed weapons than males, that the cases of independent evolution of ISWs are not evenly distributed across the phylogeny, and that animals possessing the most developed ISWs have non-hunting habits (e.g. herbivores) or are faunivores that prey on very small prey relative to their body size (e.g. insectivores). Bringing together perspectives from studies on a variety of taxa, we conceptualize that there are five ways in which a sexually dimorphic trait, apart from the primary sex traits, can be fixed: sexual selection, fecundity selection, parental role division, differential niche occupation between the sexes, and interference competition. We discuss these trends and the factors involved in the evolution of intrasexually selected weaponry in nature.
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Affiliation(s)
- Alejandro Rico-Guevara
- Department of Integrative Biology, University of California, Berkeley, 3040 Valley Life Sciences Building, Berkeley, CA, 94720, U.S.A.,Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Rd, Unit 3043, Storrs, CT, 06269, U.S.A.,Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Código Postal 11001, Bogotá DC, Colombia
| | - Kristiina J Hurme
- Department of Integrative Biology, University of California, Berkeley, 3040 Valley Life Sciences Building, Berkeley, CA, 94720, U.S.A.,Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Rd, Unit 3043, Storrs, CT, 06269, U.S.A
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15
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Chursina MA, Negrobov OP. Phylogenetic Signal in the Wing Shape in the Subfamily Dolichopodinae (Diptera, Dolichopodidae). ACTA ACUST UNITED AC 2018. [DOI: 10.1134/s0013873818050019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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16
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Moore MP, Lis C, Martin RA. Immune deployment increases larval vulnerability to predators and inhibits adult life-history traits in a dragonfly. J Evol Biol 2018; 31:1365-1376. [PMID: 29927003 DOI: 10.1111/jeb.13337] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 06/05/2018] [Accepted: 06/19/2018] [Indexed: 01/09/2023]
Abstract
While deploying immune defences early in ontogeny can trade-off with the production and maintenance of other important traits across the entire life cycle, it remains largely unexplored how features of the environment shape the magnitude or presence of these lifetime costs. Greater predation risk during the juvenile stage may particularly influence such costs by (1) magnifying the survival costs that arise from any handicap of juvenile avoidance traits and/or (2) intensifying allocation trade-offs with important adult traits. Here, we tested for predator-dependent costs of immune deployment within and across life stages using the dragonfly, Pachydiplax longipennis. We first examined how larval immune deployment affected two traits associated with larval vulnerability to predators: escape distance and foraging under predation risk. Larvae that were induced to mount an immune response had shorter escape distances but lower foraging activity in the presence of predator cues. We also induced immune responses in larvae and reared them through emergence in mesocosms that differed in the presence of large predatory dragonfly larvae (Aeshnidae spp.). Immune-challenged larvae had later emergence overall and lower survival in pools with predators. Immune-challenged males were also smaller at emergence and developed less sexually selected melanin wing coloration, but these effects were independent of predator treatment. Overall, these results highlight how mounting an immune defence early in ontogeny can have substantial ecological and physiological costs that manifest both within and across life stages.
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Affiliation(s)
- Michael P Moore
- Department of Biology, Case Western Reserve University, Cleveland, OH, USA
| | | | - Ryan A Martin
- Department of Biology, Case Western Reserve University, Cleveland, OH, USA
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17
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Moore MP, Martin RA. Trade-offs between larval survival and adult ornament development depend on predator regime in a territorial dragonfly. Oecologia 2018; 188:97-106. [PMID: 29808358 DOI: 10.1007/s00442-018-4171-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Accepted: 05/21/2018] [Indexed: 01/20/2023]
Abstract
Trade-offs between juvenile survival and the development of sexually selected traits can cause ontogenetic conflict between life stages that constrains adaptive evolution. However, the potential for ecological interactions to alter the presence or strength of these trade-offs remains largely unexplored. Antagonistic selection over the accumulation and storage of resources could be one common cause of environment-specific trade-offs between life stages: higher condition may simultaneously enhance adult ornament development and increase juvenile vulnerability to predators. We tested this hypothesis in an ornamented dragonfly (Pachydiplax longipennis). Higher larval body condition indeed enhanced the initial development of its intrasexually selected wing coloration, but was opposed by viability selection in the presence of large aeshnid predators. In contrast, viability selection did not oppose larval body condition in pools when aeshnids were absent, and was not affected when we manipulated cannibalism risk. Trade-offs between larval survival and ornament development, mediated through the conflicting effects of body condition, therefore occurred only under high predation risk. We additionally characterized how body condition influences several traits associated with predator avoidance. Although body condition did not affect burst distance, it did increase larval abdomen size, potentially making larvae easier targets for aeshnid predators. As high body condition similarly increases vulnerability to predators in many other animals, predator-mediated costs of juvenile resource accumulation could be a common, environment-specific limitation on the elaboration of sexually selected traits.
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Affiliation(s)
- Michael P Moore
- Department of Biology, Case Western Reserve University, Cleveland, OH, 44106, USA.
| | - Ryan A Martin
- Department of Biology, Case Western Reserve University, Cleveland, OH, 44106, USA
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18
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Spicer MM, Hart SL, Brighty SR, Gall BG. Absence of visual discrimination by female eastern newts during mate selection. ETHOL ECOL EVOL 2017. [DOI: 10.1080/03949370.2016.1240713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
| | - Shelby L. Hart
- Department of Biology, Hanover College, Hanover, IN 47243, USA
| | - Sara R. Brighty
- Department of Biology, Hanover College, Hanover, IN 47243, USA
| | - Brian G. Gall
- Department of Biology, Hanover College, Hanover, IN 47243, USA
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19
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Warner RR, Schultz ET. SEXUAL SELECTION AND MALE CHARACTERISTICS IN THE BLUEHEAD WRASSE, THALASSOMA BIFASCIATUM: MATING SITE ACQUISITION, MATING SITE DEFENSE, AND FEMALE CHOICE. Evolution 2017; 46:1421-1442. [PMID: 28569004 DOI: 10.1111/j.1558-5646.1992.tb01134.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/1991] [Accepted: 01/31/1992] [Indexed: 11/26/2022]
Abstract
Through a series of replacement experiments with the bluehead wrasse, Thalassoma bifasciatum, we have identified male morphological characteristics that appear to be under phenotypic sexual selection. We were particularly interested in whether the various sources of sexual selection (male-male competition for unoccupied mating sites, defense of mating sites against small males, and female choice of males) were (1) independently associated with different phenotypic characteristics; (2) jointly affected the same characteristic in the same way; or (3) jointly affected the same characteristic in an antagonistic fashion. We replaced the resident large, brightly colored Terminal Phase (TP) males on a reef with the same number of TP males from other reefs. When transplanted, these males contest with each other to take over mating sites. The transplanted group of males were then scored for three components of fitness: (1) the quality of the site obtained through competition with other large males; (2) the male's ability to defend arriving females from small intruding males; and (3) changes in female visits to the site once the new male takes over. The first and second components are part of intrasexual selection; the third represents intersexual selection. We measured the opportunity for selection by partitioning variance in mating success, and measured the direct effects of sexual selection by estimating the covariance between morphology and fitness components. Opportunities for selection: Because females generally remain faithful to particular mating sites, most (54%) of the explainable variation in male mating success is due to the acquisition of a particular mating territory, which is the outcome of competition among TP males. There was less variation in mating success due to shifts in site use by females and defense of females against the intrusions of smaller males, but all components were significant. Effects of selection: Success in male-male competition among TP males, estimated by the quality of the territory acquired, was positively associated with body length and the relative length of the pectoral fin. Success in territorial defense against small males was primarily related to body length, with lesser contributions from body depth and the area of a white band on the flank. Contribution to fitness through female choice of males was positively associated with white band area. In the two instances where a character was associated with two fitness components, the direction of selection was the same. While body length was positively associated with winning intrasexual contests, it was not correlated to any behavioral measures of aggression. Similarly, the white band associated with attractiveness was not correlated with any aspect of courtship or aggression. Parasite load was uncorrelated with other morphological characters, and did not appear to affect any aspect of sexual selection. There was no evidence for stabilizing selection or significant additional contributions from second-order effects to the fitness surfaces. Fitness functions calculated using cubic splines were generally linear except for body length, which appeared sigmoid in its effect on site acquisition ability; this same feature tended to plateau in its effect on site defense. Analyses of the interactions of selection gradients with reef or experiment indicated that the effect of particular male characters on estimates of fitness was generally homogeneous in both time and space.
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Affiliation(s)
- Robert R Warner
- Department of Biological Sciences and Marine Science Institute, University of California, Santa Barbara, CA, 93106, USA
| | - Eric T Schultz
- Department of Biological Sciences and Marine Science Institute, University of California, Santa Barbara, CA, 93106, USA
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20
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Murphy CG. INTERACTION-INDEPENDENT SEXUAL SELECTION AND THE MECHANISMS OF SEXUAL SELECTION. Evolution 2017; 52:8-18. [PMID: 28568146 DOI: 10.1111/j.1558-5646.1998.tb05133.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/1996] [Accepted: 09/16/1997] [Indexed: 11/29/2022]
Abstract
Darwin identified explicitly two types of sexual selection, male contests (combat and displays) and female choice, and he devoted the overwhelming majority of his examples to traits that influence the outcome of these interactions. Subsequent treatments of sexual selection have emphasized the importance of intra- and intersexual interactions as sources of sexual selection. However, many traits that are important determinants of mating success influence mating success without necessarily affecting the outcome of intra- and intersexual interactions. Here, I argue that traits can be subject to sexual selection even if they do not affect the outcome of intra- and intersexual interactions. I distinguish two types of sexual selection, interaction-independent and interaction-dependent selection, based on whether variance in mating success is the result of trait-dependent outcomes of interactions between conspecifics. I then use this distinction to construct a framework for classifying types of sexual selection that unifies and expands previously proposed frameworks. Finally, I outline several implications that the concept of interaction-independent sexual selection has for the general theory of sexual selection.
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21
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Wikelski M, Trillmich F. BODY SIZE AND SEXUAL SIZE DIMORPHISM IN MARINE IGUANAS FLUCTUATE AS A RESULT OF OPPOSING NATURAL AND SEXUAL SELECTION: AN ISLAND COMPARISON. Evolution 2017; 51:922-936. [PMID: 28568579 DOI: 10.1111/j.1558-5646.1997.tb03673.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/1996] [Accepted: 01/29/1997] [Indexed: 11/29/2022]
Abstract
Body size is often assumed to represent the outcome of conflicting selection pressures of natural and sexual selection. Marine iguana (Amblyrhynchus cristatus) populations in the Galápagos exhibit 10-fold differences in body mass between island populations. There is also strong sexual size dimorphism, with males being about twice as heavy as females. To understand the evolutionary processes shaping body size in marine iguanas, we analyzed the selection differentials on body size in two island populations (max. male mass 900 g in Genovesa, 3500 g in Santa Fé). Factors that usually confound any evolutionary analysis of body sizes-predation, interspecific food competition, reproductive role division-are ruled out for marine iguanas. We show that, above hatchlings, mortality rates increased with body size in both sexes to the same extent. This effect was independent of individual age. The largest animals (males) of each island were the first to die once environmental conditions deteriorated (e.g., during El Niños). This sex-biased mortality was the result of sexual size dimorphism, but at the same time caused sexual size dimorphism to fluctuate. Mortality differed between seasons (selection differentials as low as -1.4) and acted on different absolute body sizes between islands. Both males and females did not cease growth when an optimal body size for survival was reached, as demonstrated by the fact that individual adult body size phenotypically increased in each population under favorable environmental conditions beyond naturally selected limits. But why did marine iguanas grow "too large" for survival? Due to lek mating, sexual selection constantly favored large body size in males (selection differentials up to +0.77). Females only need to reach a body size sufficient to produce surviving offspring. Thereafter, large body size of females was less favored by fertility selection than large size in males. Resulting from these different selection pressures on male and female size, sexual size dimorphism was mechanistically caused by the fact that females matured at an earlier age and size than males, whereafter they constantly allocated resources into eggs, which slowed growth. The observed allometric increase in sexual size dimorphism is explained by the fact that the difference between these selective processes becomes larger as energy abundance in the environment increases. Because body size is generally highly heritable, these selective processes are expected to lead to genetic differences in body size between islands. We propose a common-garden experiment to determine the influence of genetic factors and phenotypic reaction norms of final body size.
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Affiliation(s)
- Martin Wikelski
- Department of Animal Behaviour, University of Bielefeld, Postfach 100131, D-33501, Bielefeld, Germany.,Max-Planck Institute for Behavioral Physiology, Abt. Wickler, D-82319, Seewiesen, Germany
| | - Fritz Trillmich
- Department of Animal Behaviour, University of Bielefeld, Postfach 100131, D-33501, Bielefeld, Germany
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22
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Brodie ED. CORRELATIONAL SELECTION FOR COLOR PATTERN AND ANTIPREDATOR BEHAVIOR IN THE GARTER SNAKETHAMNOPHIS ORDINOIDES. Evolution 2017; 46:1284-1298. [DOI: 10.1111/j.1558-5646.1992.tb01124.x] [Citation(s) in RCA: 261] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/1991] [Accepted: 02/22/1992] [Indexed: 11/26/2022]
Affiliation(s)
- Edmund D. Brodie
- Department of Ecology and Evolution; University of Chicago; Chicago IL 60637 USA
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23
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Preziosi RF, Fairbairn DJ. SEXUAL SIZE DIMORPHISM AND SELECTION IN THE WILD IN THE WATERSTRIDER AQUARIUS REMIGIS
: LIFETIME FECUNDITY SELECTION ON FEMALE TOTAL LENGTH AND ITS COMPONENTS. Evolution 2017; 51:467-474. [DOI: 10.1111/j.1558-5646.1997.tb02434.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/1996] [Accepted: 10/30/1996] [Indexed: 11/28/2022]
Affiliation(s)
- Richard F. Preziosi
- Department of Biology; McGill University; 1205 Docteur Penfield Montreal Quebec H3A 1B1 Canada
| | - Daphne J. Fairbairn
- Department of Biology; Concordia University; 1455 de Maisonneuve Boulevard West Montreal Quebec H3G 1M8 Canada
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24
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Grether GF. INTRASEXUAL COMPETITION ALONE FAVORS A SEXUALLY DIMORPHIC ORNAMENT IN THE RUBYSPOT DAMSELFLY
HETAERINA AMERICANA. Evolution 2017; 50:1949-1957. [DOI: 10.1111/j.1558-5646.1996.tb03582.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/1995] [Accepted: 02/26/1996] [Indexed: 11/29/2022]
Affiliation(s)
- Gregory F. Grether
- Animal Behavior Group, Division of Environmental Studies University of California Davis California 95616
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25
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Fairbairn DJ, Preziosi RF. SEXUAL SELECTION AND THE EVOLUTION OF SEXUAL SIZE DIMORPHISM IN THE WATER STRIDER,AQUARIUS REMIGIS. Evolution 2017; 50:1549-1559. [DOI: 10.1111/j.1558-5646.1996.tb03927.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/1995] [Accepted: 08/09/1995] [Indexed: 11/29/2022]
Affiliation(s)
- Daphne J. Fairbairn
- Department of Biology; Concordia University; 1455 de Maisonneuve Boulevard, West Montreal Quebec H3G 1M8 Canada
| | - Richard F. Preziosi
- Department of Biology; McGill University; 1205 Docteur Penfield Montreal Quebec H3A 1B1 Canada
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26
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Grether GF. SEXUAL SELECTION AND SURVIVAL SELECTION ON WING COLORATION AND BODY SIZE IN THE RUBYSPOT DAMSELFLY
HETAERINA AMERICANA. Evolution 2017; 50:1939-1948. [DOI: 10.1111/j.1558-5646.1996.tb03581.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/1995] [Accepted: 02/26/1996] [Indexed: 11/24/2022]
Affiliation(s)
- Gregory F. Grether
- Animal Behavior Group, Division of Environmental Studies University of California Davis California 95616
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27
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Brodie ED, Janzen FJ. ON THE ASSIGNMENT OF FITNESS VALUES IN STATISTICAL ANALYSES OF SELECTION. Evolution 2017; 50:437-442. [DOI: 10.1111/j.1558-5646.1996.tb04505.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/1994] [Accepted: 11/02/1994] [Indexed: 12/01/2022]
Affiliation(s)
- Edmund D. Brodie
- Center for Ecology, Evolution and Behavior School of Biological Sciences, University of Kentucky Lexington Kentucky 40506‐0225
| | - Fredric J. Janzen
- Department of Zoology and Genetics Iowa State University Ames Iowa 50011
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28
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Van Eeckhoven J, Huyghe K, Van Damme R. Artificial selection in guppies: male and female phenotypes produced by inter‐ and intrasexual selection. J Zool (1987) 2017. [DOI: 10.1111/jzo.12475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- J. Van Eeckhoven
- Research group of Functional Morphology Department of Biology University of Antwerp Wilrijk Belgium
| | - K. Huyghe
- Research group of Functional Morphology Department of Biology University of Antwerp Wilrijk Belgium
| | - R. Van Damme
- Research group of Functional Morphology Department of Biology University of Antwerp Wilrijk Belgium
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29
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Santos ESA, Machado G. Sexual dichromatism in wing pigmentation of New World dragonflies follows Rensch's rule. J Evol Biol 2016; 29:1447-54. [PMID: 27169873 DOI: 10.1111/jeb.12885] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Revised: 03/27/2016] [Accepted: 03/29/2016] [Indexed: 11/30/2022]
Abstract
Many animal taxa that display sexual size dimorphism (SSD) exhibit a positive allometric relationship in which the degree of dimorphism increases with body size. This macroevolutionary pattern is known as Rensch's rule. Although sexual selection is hypothesized to be the main mechanism causing this pattern, body size is influenced by several selective forces, including natural and sexual selection. Therefore, by focusing exclusively on SSD one cannot ascertain which of these selective forces drives Rensch's rule. If sexual selection is indeed the main mechanism underlying Rensch's rule, we predict that other sexually selected traits, including coloration-based ornaments, will also exhibit interspecific allometric scaling consistent with Rensch's rule. We tested this prediction using wing pigmentation of 89 species of dragonflies. Studies show that male wing pigmentation is generally under strong intra- and intersexual selection, so that sexual dichromatism in this trait should follow Rensch's rule. Conversely, the available evidence suggests that male body size is usually not sexually selected in dragonflies, so we do not expect SSD to follow Rensch's rule. First, we found that sexual dichromatism in wing pigmentation was consistent with Rensch's rule. The phylogenetic major axis regression slope was significantly greater than one. We also showed that the allometric slope for SSD was not different from unity, providing no support for Rensch's rule. Our results provide the first evidence that a trait which appears to be under strong sexual selection exhibits a pattern consistent with Rensch's rule.
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Affiliation(s)
- E S A Santos
- BECO do Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil.,LAGE do Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
| | - G Machado
- LAGE do Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
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30
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Rubalcaba JG, Polo V, Maia R, Rubenstein DR, Veiga JP. Sexual and natural selection in the evolution of extended phenotypes: the use of green nesting material in starlings. J Evol Biol 2016; 29:1585-92. [DOI: 10.1111/jeb.12893] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 05/04/2016] [Indexed: 11/29/2022]
Affiliation(s)
- J. G. Rubalcaba
- Departamento de Biología, Geología, Física y Química Inorgánica; Área de Biodiversidad y Conservación; Universidad Rey Juan Carlos; Móstoles Madrid Spain
| | - V. Polo
- Departamento de Biología, Geología, Física y Química Inorgánica; Área de Biodiversidad y Conservación; Universidad Rey Juan Carlos; Móstoles Madrid Spain
| | - R. Maia
- Department of Ecology; Evolution and Environmental Biology; Columbia University; New York NY USA
| | - D. R. Rubenstein
- Department of Ecology; Evolution and Environmental Biology; Columbia University; New York NY USA
| | - J. P. Veiga
- Departamento de Ecología Evolutiva; Museo Nacional de Ciencias Naturales; CSIC; Madrid Spain
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31
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Zhou M, Fuller RC. Intrasexual competition underlies sexual selection on male breeding coloration in the orangethroat darter, Etheostoma spectabile. Ecol Evol 2016; 6:3513-3522. [PMID: 27127609 PMCID: PMC4842022 DOI: 10.1002/ece3.2136] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 03/27/2016] [Accepted: 03/27/2016] [Indexed: 11/30/2022] Open
Abstract
Elaborate, sexually dimorphic traits are widely thought to evolve under sexual selection through female preference, male–male competition, or both. The orangethroat darter (Etheostoma spectabile) is a sexually dichromatic fish in which females exhibit no preferences for male size or coloration. We tested whether these traits affect individual reproductive success in E. spectabile when multiple males are allowed to freely compete for a female. The quality and quantity of male coloration were associated with greater success in maintaining access to the female and in spawning as the primary male (first male to participate). On the other hand, sneaking behavior showed little correlation with coloration. Male breeding coloration in E. spectabile may therefore demonstrate how intrasexual competition can be a predominant factor underlying the evolution of male ornaments.
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Affiliation(s)
- Muchu Zhou
- Department of Animal Biology University of Illinois at Urbana-Champaign Champaign Illinois 61820
| | - Rebecca C Fuller
- Department of Animal Biology University of Illinois at Urbana-Champaign Champaign Illinois 61820
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32
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Abstract
The discovery that extrapair copulation (EPC) and extrapair paternity (EPP) are common in birds led to a paradigm shift in our understanding of the evolution of mating systems. The prevalence of extrapair matings in pair-bonded species sets the stage for sexual conflict, and a recent focus has been to consider how this conflict can shape variation in extrapair mating rates. Here, we invert the causal arrow and consider the consequences of extrapair matings for sexual conflict. Extrapair matings shift sexual conflict from a simple two-player (male vs. female) game to a game with three or more players, the nature of which we illustrate with simple diagrams that highlight the net costs and benefits of extrapair matings to each player. This approach helps identify the sorts of traits that might be under selection because of sexual conflict. Whether EPP is driven primarily by the extrapair male or the within-pair female profoundly influences which players are in conflict, but the overall pattern of conflict varies little among different mating systems. Different aspects of conflict are manifest at different stages of the breeding cycle and can be profitably considered as distinct episodes of selection caused by conflict. This perspective is illuminating both because conflict between specific players can change across episodes and because the traits that evolve to mediate conflict likely differ between episodes. Although EPP clearly leads to sexual conflict, we suggest that the link between sexual conflict and multiple paternity might be usefully understood by examining how deviations from lifetime sexual monogamy influence sexual conflict.
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33
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Okada K, Katsuki M, Sharma MD, House CM, Hosken DJ. Sexual conflict over mating in Gnatocerus cornutus? Females prefer lovers not fighters. Proc Biol Sci 2014; 281:20140281. [PMID: 24807253 DOI: 10.1098/rspb.2014.0281] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Female mate choice and male-male competition are the typical mechanisms of sexual selection. However, these two mechanisms do not always favour the same males. Furthermore, it has recently become clear that female choice can sometimes benefit males that reduce female fitness. So whether male-male competition and female choice favour the same or different males, and whether or not females benefit from mate choice, remain open questions. In the horned beetle, Gnatocerus cornutus, males have enlarged mandibles used to fight rivals, and larger mandibles provide a mating advantage when there is direct male-male competition for mates. However, it is not clear whether females prefer these highly competitive males. Here, we show that female choice targets male courtship rather than mandible size, and these two characters are not phenotypically or genetically correlated. Mating with attractive, highly courting males provided indirect benefits to females but only via the heritability of male attractiveness. However, mating with attractive males avoids the indirect costs to daughters that are generated by mating with competitive males. Our results suggest that male-male competition may constrain female mate choice, possibly reducing female fitness and generating sexual conflict over mating.
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Affiliation(s)
- Kensuke Okada
- Graduate School of Environmental Science, Okayama University, , Tsushima-naka 1-1-1, Okayama 700-8530, Japan, Faculty of Life and Environmental Sciences, University of Tsukuba, , Tennoudai 1-1-1, Tsukuba 305-8572, Japan, Centre for Conservation and Ecology, College of Life and Environmental Sciences, University of Exeter, , Tremough, Penryn TR109EZ, UK
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Kumaran N, Balagawi S, Schutze MK, Clarke AR. Evolution of lure response in tephritid fruit flies: phytochemicals as drivers of sexual selection. Anim Behav 2013. [DOI: 10.1016/j.anbehav.2013.01.024] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Punzalan D, Rodd FH, Rowe L. Temporally Variable Multivariate Sexual Selection on Sexually Dimorphic Traits in a Wild Insect Population. Am Nat 2010; 175:401-14. [PMID: 20184443 DOI: 10.1086/650719] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- David Punzalan
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.
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Growth and home range size of the gracile mouse opossum Gracilinanus microtarsus (Marsupialia: Didelphidae) in Brazilian cerrado. JOURNAL OF TROPICAL ECOLOGY 2010. [DOI: 10.1017/s0266467409990526] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract:Differences in growth patterns between the sexes of the gracile mouse opossum Gracilinanus microtarsus and the consequences for home range size were investigated in a savanna habitat (cerrado) of south-eastern Brazil. A total of 51 juvenile individuals of Gracilinanus microtarsus was monitored using capture–mark–recapture from November 2005 to August 2006. The increase in body mass of gracile mouse opossums was described using the Gompertz growth model. Male gracile mouse opossums grew faster than females (dimorphic ratio of 1.5). Home range size, estimated with the minimum convex polygon method, was positively related to body mass. Model selection using Akaike's Information Criterion (AICc) and incorporating body mass, sex and season as independent variables showed that the best-supported model describing variance in home range sizes included only body mass. Our data suggest that a greater body mass gain in juvenile males is probably the proximate cause of sexual dimorphism in adult gracile mouse opossums and that energetic needs required for growth have a greater influence in home range size.
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Hunt J, Breuker CJ, Sadowski JA, Moore AJ. Male-male competition, female mate choice and their interaction: determining total sexual selection. J Evol Biol 2009; 22:13-26. [PMID: 19120810 DOI: 10.1111/j.1420-9101.2008.01633.x] [Citation(s) in RCA: 272] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Empirical studies of sexual selection typically focus on one of the two mechanisms of sexual selection without integrating these into a description of total sexual selection, or study total sexual selection without quantifying the contributions of all of the mechanisms of sexual selection. However, this can provide an incomplete or misleading view of how sexually selected traits evolve if the mechanisms of sexual selection are opposing or differ in form. Here, we take a two-fold approach to advocate a direction for future studies of sexual selection. We first show how a quantitative partitioning and examination of sexual selection mechanisms can inform by identifying illustrative studies that describe both male-male competition and female mate choice acting on the same trait. In our sample, the most common trait where this occurred was body size, and selection was typically linear. We found that male-male competition and female mate choice can be reinforcing or opposing, although the former is most common in the literature. The mechanisms of sexual selection can occur simultaneously or sequentially, and we found they were more likely to be opposing when the mechanisms operated sequentially. The degree and timing that these mechanisms interact have important implications for the operation of sexual selection and needs to be considered in designing studies. Our examples highlight where empirical data are needed. We especially lack standardized measures of the form and strength of selection imposed by each mechanism of sexual selection and how they combine to determine total sexual selection. Secondly, using quantitative genetic principles, we outline how the selection imposed by individual mechanisms can be measured and combined to estimate the total strength and form of sexual selection. We discuss the evolutionary consequences of combining the mechanisms of sexual selection and interpreting total sexual selection. We suggest how this approach may result in empirical progress in the field of sexual selection.
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Affiliation(s)
- John Hunt
- Centre for Ecology and Conservation, School of Biosciences, University of Exeter, Penryn, UK
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Whitlock MC, Agrawal AF. Purging the genome with sexual selection: reducing mutation load through selection on males. Evolution 2008; 63:569-82. [PMID: 19154364 DOI: 10.1111/j.1558-5646.2008.00558.x] [Citation(s) in RCA: 202] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Healthy males are likely to have higher mating success than unhealthy males because of differential expression of condition-dependent traits such as mate searching intensity, fighting ability, display vigor, and some types of exaggerated morphological characters. We therefore expect that most new mutations that are deleterious for overall fitness may also be deleterious for male mating success. From this perspective, sexual selection is not limited to influencing those genes directly involved in exaggerated morphological traits but rather affects most, if not all, genes in the genome. If true, sexual selection can be an important force acting to reduce the frequency of deleterious mutations and, as a result, mutation load. We review the literature and find various forms of indirect evidence that sexual selection helps to eliminate deleterious mutations. However, direct evidence is scant, and there are almost no data available to address a key issue: is selection in males stronger than selection in females? In addition, the total effect of sexual selection on mutation load is complicated by possible increases in mutation rate that may be attributable to sexual selection. Finally, sexual selection affects population fitness not only through mutation load but also through sexual conflict, making it difficult to empirically measure how sexual selection affects load. Several lines of enquiry are suggested to better fill large gaps in our understanding of sexual selection and its effect on genetic load.
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Affiliation(s)
- Michael C Whitlock
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4 Canada.
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Kingsolver JG, Hoekstra HE, Hoekstra JM, Berrigan D, Vignieri SN, Hill CE, Hoang A, Gibert P, Beerli P. The strength of phenotypic selection in natural populations. Am Nat 2008; 157:245-61. [PMID: 18707288 DOI: 10.1086/319193] [Citation(s) in RCA: 1276] [Impact Index Per Article: 79.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
How strong is phenotypic selection on quantitative traits in the wild? We reviewed the literature from 1984 through 1997 for studies that estimated the strength of linear and quadratic selection in terms of standardized selection gradients or differentials on natural variation in quantitative traits for field populations. We tabulated 63 published studies of 62 species that reported over 2,500 estimates of linear or quadratic selection. More than 80% of the estimates were for morphological traits; there is very little data for behavioral or physiological traits. Most published selection studies were unreplicated and had sample sizes below 135 individuals, resulting in low statistical power to detect selection of the magnitude typically reported for natural populations. The absolute values of linear selection gradients |beta| were exponentially distributed with an overall median of 0.16, suggesting that strong directional selection was uncommon. The values of |beta| for selection on morphological and on life-history/phenological traits were significantly different: on average, selection on morphology was stronger than selection on phenology/life history. Similarly, the values of |beta| for selection via aspects of survival, fecundity, and mating success were significantly different: on average, selection on mating success was stronger than on survival. Comparisons of estimated linear selection gradients and differentials suggest that indirect components of phenotypic selection were usually modest relative to direct components. The absolute values of quadratic selection gradients |gamma| were exponentially distributed with an overall median of only 0.10, suggesting that quadratic selection is typically quite weak. The distribution of gamma values was symmetric about 0, providing no evidence that stabilizing selection is stronger or more common than disruptive selection in nature.
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Affiliation(s)
- J G Kingsolver
- Department of Zoology, University of Washington, Seattle, Washington 98195, USA.
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The interrelationships between resource-holding potential, resource-value and reproductive success in territorial males: How much variation can we explain? Behav Ecol Sociobiol 2007. [DOI: 10.1007/s00265-007-0518-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Fincke OM, Hadrys H. UNPREDICTABLE OFFSPRING SURVIVORSHIP IN THE DAMSELFLY, MEGALOPREPUS COERULATUS, SHAPES PARENTAL BEHAVIOR, CONSTRAINS SEXUAL SELECTION, AND CHALLENGES TRADITIONAL FITNESS ESTIMATES. Evolution 2007. [DOI: 10.1111/j.0014-3820.2001.tb00812.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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42
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Johannes Mikolajewski D, Joop G, Wohlfahrt B. Coping with predators and food limitation: testing life history theory for sex-specific larval development. OIKOS 2007. [DOI: 10.1111/j.0030-1299.2007.15139.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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43
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Martínez-Lendech N, Córdoba-Aguilar A, Serrano-Meneses MA. Body size and fat reserves as possible predictors of male territorial status and contest outcome in the butterfly Eumaeus toxea Godart (Lepidoptera: Lycaenidae). J ETHOL 2007. [DOI: 10.1007/s10164-007-0040-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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44
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JOHANSSON FRANK, CROWLEY PHILIPH, BRODIN TOMAS. Sexual size dimorphism and sex ratios in dragonflies (Odonata). Biol J Linn Soc Lond 2005. [DOI: 10.1111/j.1095-8312.2005.00549.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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45
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Sussman RW, Cheverud JM, Bartlett TQ. Infant killing as an evolutionary strategy: Reality or myth? Evol Anthropol 2005. [DOI: 10.1002/evan.1360030502] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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McGlothlin JW, Parker PG, Nolan V, Ketterson ED. CORRELATIONAL SELECTION LEADS TO GENETIC INTEGRATION OF BODY SIZE AND AN ATTRACTIVE PLUMAGE TRAIT IN DARK-EYED JUNCOS. Evolution 2005. [DOI: 10.1554/04-163] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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47
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Bonduriansky R, Rowe L. Interactions among mechanisms of sexual selection on male body size and head shape in a sexually dimorphic fly. Evolution 2004; 57:2046-53. [PMID: 14575326 DOI: 10.1111/j.0014-3820.2003.tb00384.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Darwin envisaged male-male and male-female interactions as mutually supporting mechanisms of sexual selection, in which the best armed males were also the most attractive to females. Although this belief continues to predominate today, it has been challenged by sexual conflict theory, which suggests that divergence in the interests of males and females may result in conflicting sexual selection. This raises the empirical question of how multiple mechanisms of sexual selection interact to shape targeted traits. We investigated sexual selection on male morphology in the sexually dimorphic fly Prochyliza xanthostoma, using indices of male performance in male-male and male-female interactions in laboratory arenas to calculate gradients of direct, linear selection on male body size and an index of head elongation. In male-male combat, the first interaction with a new opponent selected for large body size but reduced head elongation, whereas multiple interactions with the same opponent favored large body size only. In male-female interactions, females preferred males with relatively elongated heads, but male performance of the precopulatory leap favored large body size and, possibly, reduced head elongation. In addition, the amount of sperm transferred (much of which is ingested by females) was an increasing function of both body size and head elongation. Thus, whereas both male-male and male-female interactions favored large male body size, male head shape appeared to be subject to conflicting sexual selection. We argue that conflicting sexual selection may be a common result of divergence in the interests of the sexes.
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Blows MW, Brooks R. Measuring Nonlinear Selection. Am Nat 2003; 162:815-20. [PMID: 14737718 DOI: 10.1086/378905] [Citation(s) in RCA: 245] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2003] [Accepted: 06/02/2003] [Indexed: 11/03/2022]
Affiliation(s)
- Mark W Blows
- Department of Zoology and Entomology, University of Queensland, Brisbane 4072, Australia.
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50
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Ostner J, Heistermann M, Kappeler PM. Intersexual dominance, masculinized genitals and prenatal steroids: comparative data from lemurid primates. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2003; 90:141-4. [PMID: 12649757 DOI: 10.1007/s00114-003-0404-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2002] [Accepted: 01/19/2003] [Indexed: 11/28/2022]
Abstract
Masculinization of female genitalia and female intersexual dominance distinguish spotted hyenas (Crocuta crocuta) and Malagasy primates (Lemuriformes) from most other mammals. An unusual prenatal endocrine environment has been proposed to proximately underlie the development of these traits in hyenas. To examine whether female dominance and genital masculinization are similarly enhanced by the prenatal environment in lemurid primates, we measured androgen and estrogen excretion in pregnant wild redfronted lemurs (Eulemur fulvus rufus). Our results showed that estrogen levels during the second phase of gestation were much higher in females carrying a male fetus than in female-carrying mothers. This may indicate the onset of testicular activity in male fetuses, because androgens of fetal origin are aromatized to maternal estrogens. Levels of androgen excretion were similar in all mothers regardless of the fetus' sex, which may suggest that androgen-independent mechanisms also contribute to female masculinization. The much higher androgen/estrogen ratio in female-carrying mothers indicates that relative, rather than absolute, prenatal steroid concentrations may play a role in female masculinization.
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Affiliation(s)
- Julia Ostner
- Abteilung Verhaltensforschung and Okologie, Deutsches Primatenzentrum, Kellnerweg 4, 37077 Göttingen, Germany.
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