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Hasegawa M. Occurrence and persistence of pseudo-tail spots in the barn swallow. Ecol Evol 2024; 14:e11669. [PMID: 38994209 PMCID: PMC11239207 DOI: 10.1002/ece3.11669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 06/09/2024] [Accepted: 06/17/2024] [Indexed: 07/13/2024] Open
Abstract
While numerous studies have confirmed sexual selection for ornamental traits in animals, it remains unclear about how animals exaggerate ornamentation across traits. I found that some Asian barn swallows Hirundo rustica gutturalis possessed "pseudo-tail spots" on their undertail coverts adjacent to a well-known sexual signal, the white tail spots. A close inspection showed their remarkable resemblance, and, as a consequence, pseudo-tail spots appear to add white spots to the uniformly black central tail feathers, increasing the total number and area of white spots when spread tails are viewed from below. Pseudo-tail spots on the undertail covers do not incur any flight cost, unlike the white tail spots on the tail itself, and thus presence of pseudo-tail spots can represent an initial stage of a deceptive elaboration as predicted by sexual selection theory (i.e., males can elaborate traits with no additional flight cost, uncoupling flight cost and trait expression). The frequency of pseudo-tail spots in the study population remained low even a decade after the first observation (ca. 7%), but was higher compared to other populations (e.g., 1% in another Japanese population). The slow progress of evolution, perhaps due to the low detectability of the trait, provides a unique opportunity to observe contemporary evolution of ornament exaggeration across traits. Further research with wider spatial and temporal coverage is needed to better understand the evolutionary and ecological importance of the trait.
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Affiliation(s)
- Masaru Hasegawa
- Department of Environmental ScienceIshikawa Prefectural UniversityNonoichiIshikawaJapan
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2
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Weber JN, Kojima W, Boisseau RP, Niimi T, Morita S, Shigenobu S, Gotoh H, Araya K, Lin CP, Thomas-Bulle C, Allen CE, Tong W, Lavine LC, Swanson BO, Emlen DJ. Evolution of horn length and lifting strength in the Japanese rhinoceros beetle Trypoxylus dichotomus. Curr Biol 2023; 33:4285-4297.e5. [PMID: 37734374 DOI: 10.1016/j.cub.2023.08.066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 06/28/2023] [Accepted: 08/23/2023] [Indexed: 09/23/2023]
Abstract
What limits the size of nature's most extreme structures? For weapons like beetle horns, one possibility is a tradeoff associated with mechanical levers: as the output arm of the lever system-the beetle horn-gets longer, it also gets weaker. This "paradox of the weakening combatant" could offset reproductive advantages of additional increases in weapon size. However, in contemporary populations of most heavily weaponed species, males with the longest weapons also tend to be the strongest, presumably because selection drove the evolution of compensatory changes to these lever systems that ameliorated the force reductions of increased weapon size. Therefore, we test for biomechanical limits by reconstructing the stages of weapon evolution, exploring whether initial increases in weapon length first led to reductions in weapon force generation that were later ameliorated through the evolution of mechanisms of mechanical compensation. We describe phylogeographic relationships among populations of a rhinoceros beetle and show that the "pitchfork" shaped head horn likely increased in length independently in the northern and southern radiations of beetles. Both increases in horn length were associated with dramatic reductions to horn lifting strength-compelling evidence for the paradox of the weakening combatant-and these initial reductions to horn strength were later ameliorated in some populations through reductions to horn length or through increases in head height (the input arm for the horn lever system). Our results reveal an exciting geographic mosaic of weapon size, weapon force, and mechanical compensation, shedding light on larger questions pertaining to the evolution of extreme structures.
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Affiliation(s)
- Jesse N Weber
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA.
| | - Wataru Kojima
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8511, Japan
| | - Romain P Boisseau
- Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA
| | - Teruyuki Niimi
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka Myodaiji, Okazaki 444-8585, Japan
| | - Shinichi Morita
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka Myodaiji, Okazaki 444-8585, Japan
| | - Shuji Shigenobu
- Trans-Scale Biology Center, National Institute for Basic Biology, 38 Nishigonaka Myodaiji, Okazaki 444-8585, Japan
| | - Hiroki Gotoh
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, 836 Oya, Suruga Ward, Shizuoka, Japan
| | - Kunio Araya
- Faculty of Social and Cultural Studies, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka-city Fukuoka 819-0395, Japan
| | - Chung-Ping Lin
- Department of Life Science, National Taiwan Normal University, No.88 Sec. 4, Tingzhou Rd, Taipei 11677, Taiwan
| | - Camille Thomas-Bulle
- Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA; Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Cerisse E Allen
- Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA
| | - Wenfei Tong
- Cornell Laboratory of Ornithology, Ithaca, NY 14850, USA
| | - Laura Corley Lavine
- Department of Entomology, Washington State University, Pullman, WA 99164, USA
| | - Brook O Swanson
- Department of Biology, Gonzaga University, 502 East Boone Avenue, Spokane, WA 99258-0102, USA
| | - Douglas J Emlen
- Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA.
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3
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Delhey K, Valcu M, Muck C, Dale J, Kempenaers B. Evolutionary predictors of the specific colors of birds. Proc Natl Acad Sci U S A 2023; 120:e2217692120. [PMID: 37579151 PMCID: PMC10450850 DOI: 10.1073/pnas.2217692120] [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: 10/17/2022] [Accepted: 06/23/2023] [Indexed: 08/16/2023] Open
Abstract
Animal coloration is one of the most conspicuous aspects of human-perceived organismal diversity, yet also one of the least understood. In particular, explaining why species have specific colors (e.g., blue vs. red) has proven elusive. Here, we quantify for nearly all bird species, the proportion of the body covered by each of 12 human-visible color categories, and test whether existing theory can predict the direction of color evolution. The most common colors are black, white, gray and brown, while the rarest are green, blue, purple, and red. Males have more blue, purple, red, or black, whereas females have more yellow, brown, or gray. Sexual dichromatism is partly due to sexual selection favoring ornamental colors in males but not in females. However, sexual selection also correlated positively with brown in both sexes. Strong social selection favors red and black, colors used in agonistic signaling, with the strongest effects in females. Reduced predation risk selects against cryptic colors (e.g., brown) and favors specific ornamental colors (e.g., black). Nocturnality is mainly associated with brown. The effects of habitat use support the sensory drive theory for camouflage and signaling. Darker colors are more common in species living in wet and cold climates, matching ecogeographical rules. Our study unambiguously supports existing theories of color evolution across an entire class of vertebrates, but much variation remains unexplained.
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Affiliation(s)
- Kaspar Delhey
- Department of Ornithology, Max Planck Institute for Biological Intelligence, 82319Seewiesen, Germany
| | - Mihai Valcu
- Department of Ornithology, Max Planck Institute for Biological Intelligence, 82319Seewiesen, Germany
| | - Christina Muck
- Department of Ornithology, Max Planck Institute for Biological Intelligence, 82319Seewiesen, Germany
| | - James Dale
- School of Natural Sciences, Massey University, Palmerston North4442, New Zealand
| | - Bart Kempenaers
- Department of Ornithology, Max Planck Institute for Biological Intelligence, 82319Seewiesen, Germany
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4
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Hasegawa M. Macroevolutionary analysis of swallows revives the sight-line hypothesis. Behav Ecol Sociobiol 2023. [DOI: 10.1007/s00265-023-03294-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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5
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Nolazco S, Delhey K, Fan M, Hall ML, Kingma SA, Roast MJ, Teunissen N, Peters A. Which plumage patches provide information about condition and success in a female fairy-wren? Behav Ecol 2022. [DOI: 10.1093/beheco/arac096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Abstract
Recent evidence suggests that female ornaments can commonly act as signals. However, how signaling functions might be affected by the tendency for reduced ornament elaboration in relation to males is less well-understood. We address this in mutually ornamented purple-crowned fairy-wrens. We investigated putatively ornamental (tail, ear coverts, crown) and non-ornamental (throat, back) plumage patches in females and compared our findings to previous studies in males. Both sexes have brown backs, buff-white throats, and turquoise-blue tails (bluer in males), while ear coverts are rufous in females and black in males. Both sexes also have a seasonal crown (slate-gray in females, black-and-purple in males). Dominant (breeder) females expressed more complete and grayer (more ornamented) crowns, although variation in coloration should not be discriminable by individuals. Unexpectedly, subordinates showed more colorful (saturated) rufous ear coverts, which should be discriminable. Condition-dependence was only evident for crown completeness (% slate-gray cover). Females with more reddish-brown backs were more reproductively successful. Variation in plumage characteristics did not explain differential allocation by mates or chances of gaining dominance. Our outcomes were not entirely consistent with findings in males. The most notable disparity was for the crown, a signal used in male-male competition that in females seems to be expressed as an incomplete version of the male crown that is not associated with fitness benefits. Our study shows that in a species, multiple traits can vary in their information content and that female ornaments can sometimes be less informative than in males, even those that are produced seasonally.
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Affiliation(s)
- Sergio Nolazco
- School of Biological Sciences, Monash University , 25 Rainforest Walk, Clayton, Victoria 3800 , Australia
| | - Kaspar Delhey
- School of Biological Sciences, Monash University , 25 Rainforest Walk, Clayton, Victoria 3800 , Australia
- Max Planck Institute for Ornithology , Seewiesen , Germany
| | - Marie Fan
- School of Biological Sciences, Monash University , 25 Rainforest Walk, Clayton, Victoria 3800 , Australia
| | - Michelle L Hall
- Max Planck Institute for Ornithology , Seewiesen , Germany
- School of Biological Sciences, University of Western Australia , 35 Stirling Highway, Perth, Western Australia 6009 , Australia
| | - Sjouke A Kingma
- Max Planck Institute for Ornithology , Seewiesen , Germany
- Behavioural Ecology Group, Department of Animal Sciences, Wageningen University and Research , De Elst 1, 6708 WD Wageningen , The Netherlands
| | - Michael J Roast
- School of Biological Sciences, Monash University , 25 Rainforest Walk, Clayton, Victoria 3800 , Australia
| | - Niki Teunissen
- School of Biological Sciences, Monash University , 25 Rainforest Walk, Clayton, Victoria 3800 , Australia
| | - Anne Peters
- School of Biological Sciences, Monash University , 25 Rainforest Walk, Clayton, Victoria 3800 , Australia
- Max Planck Institute for Ornithology , Seewiesen , Germany
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6
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Summers TC, Ord TJ. Signal detection shapes ornament allometry in functionally convergent Caribbean Anolis and Southeast Asian Draco lizards. J Evol Biol 2022; 35:1508-1523. [PMID: 36177770 PMCID: PMC9828585 DOI: 10.1111/jeb.14102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 07/10/2022] [Accepted: 07/21/2022] [Indexed: 01/12/2023]
Abstract
Visual ornaments have long been assumed to evolve hyper-allometry as an outcome of sexual selection. Yet growing evidence suggests many sexually selected morphologies can exhibit other scaling patterns with body size, including hypo-allometry. The large conspicuous throat fan, or dewlap, of arboreal Caribbean Anolis lizards was one ornament previously thought to conform to the classical expectation of hyper-allometry. We re-evaluated this classic example alongside a second arboreal group of lizards that has also independently evolved a functionally equivalent dewlap, the Southeast Asian Draco lizards. Across multiple closely related species in both genera, the Anolis and Draco dewlaps were either isometric or had hypo-allometric scaling patterns. In the case of the Anolis dewlap, variation in dewlap allometry was predicted by the distance of conspecifics and the light environment in which the dewlap was typically viewed. Signal efficacy, therefore, appears to have driven the evolution of hypo-allometry in what was originally thought to be a sexually selected ornament with hyper-allometry. Our findings suggest that other elaborate morphological structures used in social communication might similarly exhibit isometric or hypo-allometric scaling patterns because of environmental constraints on signal detection.
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Affiliation(s)
- Thomas C. Summers
- Evolution and Ecology Research Centre, and the School of Biological, Earth and Environmental SciencesUniversity of New South WalesKensingtonNew South WalesAustralia
| | - Terry J. Ord
- Evolution and Ecology Research Centre, and the School of Biological, Earth and Environmental SciencesUniversity of New South WalesKensingtonNew South WalesAustralia
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7
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Nolazco S, Delhey K, Nakagawa S, Peters A. Ornaments are equally informative in male and female birds. Nat Commun 2022; 13:5917. [PMID: 36207296 PMCID: PMC9546859 DOI: 10.1038/s41467-022-33548-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 09/22/2022] [Indexed: 11/09/2022] Open
Abstract
Female ornaments are often reduced, male-like traits. Although these were long perceived as non-functional, it is now broadly accepted that female ornaments can be adaptive. However, it is unclear whether this is as common in females as it is in males, and whether ornaments fulfil similar signalling roles. Here, we apply a bivariate meta-analysis to a large dataset of ornaments in mutually ornamented birds. As expected, female ornament expression tends to be reduced compared to males. However, ornaments are equally strongly associated with indicators of condition and aspects of reproductive success in both sexes, regardless of the degree of sexual dimorphism. Thus, we show here in a paired comparison within-and-across species, that ornaments in birds provide similar information in both sexes: more ornamented individuals are in better condition and achieve higher reproductive success. Although limited by their correlational nature, these outcomes imply that female ornaments could widely function in a similar manner as male ornaments.
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Affiliation(s)
- Sergio Nolazco
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, VIC, 3800, Australia.
| | - Kaspar Delhey
- Max Planck Institute for Ornithology, Seewiesen, Germany.
| | - Shinichi Nakagawa
- Evolution & Ecology Research Centre and School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Anne Peters
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, VIC, 3800, Australia.
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8
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9
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Shorter-legged males start breeding earlier in the barn swallow. J ETHOL 2021. [DOI: 10.1007/s10164-021-00708-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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10
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O'Brien DM. Static Scaling and the Evolution of Extreme Canine Size in a Saber-Toothed Cat (Smilodon fatalis). Integr Comp Biol 2019; 59:1303-1311. [PMID: 31120517 DOI: 10.1093/icb/icz054] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The canines of saber-toothed cats are a classic example of an extreme morphology, yet important questions pertaining to their evolution remain unanswered. Recent analyses suggest these structures functioned as tools of intrasexual combat where trait size acts as both a weapon of battle and signal of competitive ability. However, classic skeletal reconstructions suggest saber-tooth canines evolved as specialized hunting tools. Either scenario could have led to the evolution of extreme canine size and distinguishing between these hypotheses is therefore difficult. This is made more challenging by the fact that natural observation of saber-toothed cats is impossible, and biologists must rely on measures of static morphology to study the patterns of selection that favored extreme canine size. Here I analyze the static intraspecific scaling relationship between canine size and body size in the saber-toothed cat, Smilodon fatalis, to determine whether or not extreme canine size functioned as a sexually selected signal. I review the literature surrounding the evolution of sexually selected signals and the methods recently established by O'Brien et al. (2018), show how static scaling relationships can be useful, reliable tools for inferring patterns of selection, especially in fossil organisms, and provide evidence that extreme canine size in saber-toothed cats was not the product of selection for effective sexual signals, but instead evolved as either a pure intrasexually selected weapon or a hunting tool.
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Affiliation(s)
- D M O'Brien
- Department of Biological Sciences, Colby College, 5720 Mayflower Hill Drive, Waterville, ME 04901, USA
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11
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Perez DM, Backwell PRY. Selection for conspicuous visual signals in a fiddler crab. Behav Ecol Sociobiol 2019. [DOI: 10.1007/s00265-019-2670-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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12
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Hasegawa M, Arai E, Ito S, Wakamatsu K. Evolution of short tails and breakdown of honest signaling system during a severe winter in the Pacific swallow Hirundo tahitica. Evol Ecol 2019. [DOI: 10.1007/s10682-019-09978-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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13
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Goldberg DL, Landy JA, Travis J, Springer MS, Reznick DN. In love and war: The morphometric and phylogenetic basis of ornamentation, and the evolution of male display behavior, in the livebearer genus
Poecilia. Evolution 2019; 73:360-377. [DOI: 10.1111/evo.13671] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 12/06/2018] [Accepted: 12/09/2018] [Indexed: 11/28/2022]
Affiliation(s)
- Daniel L. Goldberg
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences Illinois State University Normal Illinois 61761
- Department of Biology University of California Riverside California 92521
| | - Joseph A. Landy
- Department of Biological Science Florida State University Tallahassee Florida 32306
| | - Joseph Travis
- Department of Biological Science Florida State University Tallahassee Florida 32306
| | - Mark S. Springer
- Department of Biology University of California Riverside California 92521
| | - David N. Reznick
- Department of Biology University of California Riverside California 92521
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14
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On the evolution of extreme structures: static scaling and the function of sexually selected signals. Anim Behav 2018. [DOI: 10.1016/j.anbehav.2018.08.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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15
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Mobley KB, Morrongiello JR, Warr M, Bray DJ, Wong BBM. Female ornamentation and the fecundity trade-off in a sex-role reversed pipefish. Ecol Evol 2018; 8:9516-9525. [PMID: 30377519 PMCID: PMC6194251 DOI: 10.1002/ece3.4459] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 07/14/2018] [Accepted: 07/20/2018] [Indexed: 11/12/2022] Open
Abstract
Sexual ornaments found only in females are a rare occurrence in nature. One explanation for this is that female ornaments are costly to produce and maintain and, therefore, females must trade-off resources related to reproduction to promote ornament expression. Here, we investigate whether a trade-off exists between female ornamentation and fecundity in the sex-role reversed, wide-bodied pipefish, Stigmatopora nigra. We measured two components of the disk-shaped, ventral-striped female ornament, body width, and stripe thickness. After controlling for the influence of body size, we found no evidence of a cost of belly width or stripe thickness on female fecundity. Rather, females that have larger ornaments have higher fecundity and thus accurately advertise their reproductive value to males without incurring a cost to fecundity. We also investigated the relationship between female body size and egg size and found that larger females suffer a slight decrease in egg size and fecundity, although this decrease was independent of female ornamentation. More broadly, considered in light of similar findings in other taxa, lack of an apparent fecundity cost of ornamentation in female pipefish underscores the need to revisit theoretical assumptions concerning the evolution of female ornamentation.
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Affiliation(s)
- Kenyon B. Mobley
- Department of Evolutionary EcologyMax Planck Institute for Evolutionary BiologyPlönGermany
| | | | - Matthew Warr
- School of Biological SciencesMonash UniversityMelbourneVictoriaAustralia
| | - Dianne J. Bray
- Vertebrate ZoologyMuseum VictoriaMelbourneVictoriaAustralia
| | - Bob B. M. Wong
- School of Biological SciencesMonash UniversityMelbourneVictoriaAustralia
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16
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Eberhard WG, Rodríguez RL, Huber BA, Speck B, Miller H, Buzatto BA, Machado G. Sexual Selection and Static Allometry: The Importance of Function. QUARTERLY REVIEW OF BIOLOGY 2018. [DOI: 10.1086/699410] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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17
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18
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Hasegawa M, Arai E. Female Attraction to Higher Pitched Male Enticement Calls in Barn Swallows. Ethology 2016. [DOI: 10.1111/eth.12492] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Masaru Hasegawa
- Department of Evolutionary Studies of Biosystems; Sokendai (The Graduate University for Advanced Studies); Miura-gun, Kanagawa Japan
| | - Emi Arai
- Division of Ecology and Evolutionary Biology; Graduate School of Life Sciences; Tohoku University; Aoba-ku, Sendai Japan
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19
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Chou CC, Iwasa Y, Nakazawa T. Incorporating an ontogenetic perspective into evolutionary theory of sexual size dimorphism. Evolution 2016; 70:369-84. [DOI: 10.1111/evo.12857] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 11/20/2015] [Accepted: 12/02/2015] [Indexed: 11/28/2022]
Affiliation(s)
- Chun-Chia Chou
- Department of Life Sciences; National Cheng Kung University; Tainan Taiwan
| | - Yoh Iwasa
- Department of Biology; Kyushu University; Fukuoka Japan
| | - Takefumi Nakazawa
- Department of Life Sciences; National Cheng Kung University; Tainan Taiwan
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20
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Ord TJ, Klomp DA, Garcia-Porta J, Hagman M. Repeated evolution of exaggerated dewlaps and other throat morphology in lizards. J Evol Biol 2015; 28:1948-64. [DOI: 10.1111/jeb.12709] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 07/15/2015] [Accepted: 07/29/2015] [Indexed: 01/16/2023]
Affiliation(s)
- T. J. Ord
- Evolution and Ecology Research Centre; School of Biological, Earth and Environmental Sciences; The University of New South Wales; Kensington NSW Australia
| | - D. A. Klomp
- Evolution and Ecology Research Centre; School of Biological, Earth and Environmental Sciences; The University of New South Wales; Kensington NSW Australia
| | - J. Garcia-Porta
- Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra); Barcelona Spain
| | - M. Hagman
- Evolution and Ecology Research Centre; School of Biological, Earth and Environmental Sciences; The University of New South Wales; Kensington NSW Australia
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21
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Tazzyman SJ, Iwasa Y, Pomiankowski A. The handicap process favors exaggerated, rather than reduced, sexual ornaments. Evolution 2014; 68:2534-49. [PMID: 24837599 PMCID: PMC4277338 DOI: 10.1111/evo.12450] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 05/07/2014] [Indexed: 11/28/2022]
Abstract
Why are traits that function as secondary sexual ornaments generally exaggerated in size compared to the naturally selected optimum, and not reduced? Because they deviate from the naturally selected optimum, traits that are reduced in size will handicap their bearer, and could thus provide an honest signal of quality to a potential mate. Thus if secondary sexual ornaments evolve via the handicap process, current theory suggests that reduced ornamentation should be as frequent as exaggerated ornamentation, but this is not the case. To try to explain this discrepancy, we analyze a simple model of the handicap process. Our analysis shows that asymmetries in costs of preference or ornament with regard to exaggeration and reduction cannot fully explain the imbalance. Rather, the bias toward exaggeration can be best explained if either the signaling efficacy or the condition dependence of a trait increases with size. Under these circumstances, evolution always leads to more extreme exaggeration than reduction: although the two should occur just as frequently, exaggerated secondary sexual ornaments are likely to be further removed from the naturally selected optimum than reduced ornaments.
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Affiliation(s)
- Samuel J Tazzyman
- CoMPLEX, , University College London, London WC1E 6BT, United Kingdom; Institute of Integrative Biology (IBZ), ETH Zürich, Zürich 8092, Switzerland; The Galton Laboratory, , Department of Genetics, Environment, and Evolution, , University College London, London WC1E 6BT, United Kingdom.
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