Sexual Selection

Multiple cues in mate selection: the sexual interference hypothesis

by George A. Lozano

Lozano, G. A. 2009. Multiple cues in mate selection: the sexual interference hypothesis. BioScience Hypotheses 2: 37-42

Animals use multiple cues when choosing mates, but it is not yet clear why a single signal would not suffice. In this... more Animals use multiple cues when choosing mates, but it is not yet clear why a single signal would not suffice. In this paper, drawing support from predation and “noise” effects on mate choice, marketing economics, and models on sexual signals, a new hypothesis explaining multiple sexual signals is proposed: the sexual interference hypothesis. The hypothesis is based on three well-supported premises: (1) selectivity decreases when mate assessment costs increase, (2) assessment costs increase when the propagation or reception of sexual signals is more difficult, and (3) males not only exploit such circumstances by courting females when choice is more difficult, but actively interfere with females’ preferences by making choice more difficult. The hypothesis argues that additional sexual signals evolve as a way for males to hinder female mate choice by interfering with the propagation and reception of other males’ sexual signals. Females respond by evolving the ability to glean meaningful information from signals despite males’ attempts at obfuscation. In turn, males respond by producing better interference signals and signals that are not so easily blocked. This co-evolutionary process increases the costs of assessment for females and the costs of signal production for males, and leads to a temporary equilibrium of honest advertising via multiple signals.

The other side of the coin: intersexual selection and the expression of emotions to signal youth or maturity

by George A. Lozano

Lozano, G. A. 2009. The other side of the coin: intersexual selection and the expression of emotions to signal youth or maturity. Behavioral and Brain Sciences 32(5): 398-399.

Vigil summarizes sex-related differences in emotivity, and presents a psychological model based on the restrictive... more Vigil summarizes sex-related differences in emotivity, and presents a psychological model based on the restrictive assumption that responses to stimuli are dichotomous. The model uses for support the concept of intrasexual selection, but ignores intersexual selection. An alternative hypothesis might be that emotivity signals age: maturity in men and youth in women. Integration requires considering all evolutionary biology, not just agreeable concepts.

SUPPORT FOR THE IMMUNOCOMPETENCE HANDICAP HYPOTHESIS IN THE WILD: HORMONAL MANIPULATION DECREASES SURVIVAL IN SICK DAMSELFLIES

by Roberto Munguia-Steyer

Daniel M. González-Tokman, Roberto Munguía-Steyer, Isaac González-Santoyo, Fernanda S. Baena-Díaz, Alex Córdoba-Aguilar. Evolution. DOI: 10.1111/j.1558-5646.2012.01678.x

The immunocompetence handicap hypothesis (ICHH) states that hormones enhance sexual trait expression but impair... more The immunocompetence handicap hypothesis (ICHH) states that hormones enhance sexual trait expression but impair immunity. Previous tests of the ICHH have been hampered by experimental design problems. Here we report on an experimental test of the ICHH that includes manipulations of both hormones and infections in males of the territorial damselfly, Hetaerina americana, with accurate survival measurements. We conducted a fully factorial experiment subjecting each individual to one of three topical treatments: methoprene (a juvenile hormone analog), acetone, or control, and one of three injection treatments: bacteria, PBS, or control. We measured survival of manipulated males in both the wild and in captivity. As predicted, survival was most heavily impaired in methoprene-bacteria males than in the other groups in the wild, and no survival differences emerged in captive animals. This result confirms that survival is one cost an animal pays for increased hormonal levels. This corroborates theoretical predictions of the ICHH.

Froman, D. P., Pizarri, T., Feltmann, A. J., Castillo-Juárez, H., and Birkhead, T. (2002). Sperm mobility: mechanisms of fertilizing efficiency, genetic variation, and phenotypic relationship with male status in the domestic fowl, Gallus gallus domesticus. Proceedings of the Royal Society of London B. 69 (1491): 607-612.

by Héctor Castillo-Juárez

H Rider Haggard's She and Darwin's Theory of Sexual Selection

by alex catizone

Testing a postulated case of intersexual selection in humans: the role of foot size in judgments of physical attractiveness and age

by Geoff Kushnick

Fessler, D., Stieger, S., Asaridou, S., Bahia, U., Cravalho, M., de Barros, P., Delgado, T., Fisher, M., Frederick, D., Geraldo Perez, P., Goetz, C., Haley, K., Jackson, J., Kushnick, G., Lew, K., Pain, B., Pisor, A., Sinaga, E., Sinaga, L., et al.
Evolution & Human Behavior 33:147-164 (2012)
doi: 10.1016/j.evolhumbehav.2011.08.002

The constituents of attractiveness differ across the sexes. Many relevant traits are dimorphic, suggesting that they... more The constituents of attractiveness differ across the sexes. Many relevant traits are dimorphic, suggesting that they are the product of intersexual selection. However, direction of causality is generally difficult to determine, as aesthetic criteria can as readily result from, as cause, dimorphism. Women have proportionately smaller feet than men. Prior work on the role of foot size in attractiveness suggests an asymmetry across the sexes, as small feet enhance female appearance, yet average, rather than large, feet are preferred on men. Previous investigations employed crude stimuli and limited samples. Here, we report on multiple cross-cultural studies designed to overcome these limitations. With the exception of one rural society, we find that small foot size is preferred when judging women, yet no equivalent preference applies to men. Similarly, consonant with the thesis that a preference for youth underlies intersexual selection acting on women, we document an inverse relationship between foot size and perceived age. Examination of preferences regarding, and inferences from, feet viewed in isolation suggests different roles for proportionality and absolute size in judgments of female and male bodies. Although the majority of these results bolster the conclusion that pedal dimorphism is the product of intersexual selection, the picture is complicated by the reversal of the usual preference for small female feet found in one rural society. While possibly explicable in terms of greater emphasis on female economic productivity relative to beauty, the latter finding underscores the importance of employing diverse samples when exploring postulated evolved aesthetic preferences.

Condition-dependent resource value affects male–male competition in the blue–black grassquit

by Eduardo S A Santos

Santos ESA, Maia R & Macedo RH. 2009. Behavioral Ecology, 20, 553-559

Male–male competition frequently can be resolved without overt aggression through the use of behavioral and phenotypic... more Male–male competition frequently can be resolved without overt aggression through the use of behavioral and phenotypic traits that signal body condition, dominance status, and fighting ability. In this study, we used male blue–black grassquits (Volatinia jacarina) to examine the relationship between male dominance status and behavioral, body condition, and ornamental traits in intrasexual agonistic encounters over a food resource. We found an association between body condition and winning, where winners were lighter than losers. This pattern was explained by low amounts of aggression exhibited by losers when they were heavy. In addition to being lighter, winners were, on average, up to 5 times more aggressive than the heavier losers. There were no associations between ornamental characteristics and dominance status, which suggests that male blue–black grassquits do not exhibit a badge signaling body condition and fighting ability, and we propose that such ornamental characteristics may be more functional in mate-choice contexts. However, the amount of male nuptial plumage of winners predicted the aggressiveness of their opponents, suggesting a social cost for sustaining this ornament.

MHC genotype and ornamentation

by Mats Grahn

Spacing behaviour of male pheasants, Phasianus colchicus, in relation to dominance and mate acquisition

by Mats Grahn

Artificial selection for increased comb size and its effects on other sexual characters and viability in Gallus domesticus (the domestic chicken)

by Mats Grahn

Fashion and age in pheasants: age differences in mate choice

by Mats Grahn

Female choice selects for a viability-based male trait in pheasants

by Mats Grahn

MHC genotype and male ornamentation: genetic evidence for the Hamilton-Zuk model

by Mats Grahn

Strategic female reproductive investment in response to male attractiveness in birds

by Tereza Horvathova

ISDP Short-Term Mating Interests

by David Schmitt

Evolutionary Aesthetics and Sexual Selection in the Evolution of Rock Art Aesthetic - Varella, Souza & Ferreira, 2011 Rock Art Research

by Marco Varella

This paper was accepted for comment treatment, it has received seven stimulating comments for which we authors made a reply called "Approaches, concepts, universalities and sexual selection on the evolution of palaeoart appreciation". Everything is at the same file.

This research was supported by the Brazilian funding
agency CNPq (Conselho Nacional de Desenvolvimento Científico
e Tecnológico). We authors are grateful to Thomas Heyd
and John Clegg for helpful comments on our core idea, to
Jerry Hogan for his helpful comments and review of earlier
and final versions of this manuscript, and to RAR referees
Duncan Caldwell, Ben Watson and an anonymous reviewer
for being very supportive, giving many helpful comments
and indicating detailed instructions on how to improve this
paper. This research was presented in earlier versions as
a talk during the Rock Art Aesthetic session at the IFRAO
Global Rock Art Congress in São Raimundo Nonato, Piauí
State, Brazil.


Marco Antônio Corrêa Varella, Altay Alves Lino de Souza
and José Henrique Benedetti Piccoli Ferreira
Laboratory of Comparative Psychology and Ethology
Department of Experimental Psychology
Institute of Psychology
Universidade de São Paulo
Brazil
E-mails: macvarella@usp.br, altayals@gmail.com,
jh.benedetti@gmail.com

This theoretical proposal applies evolutionary aesthetic, animal signalling and sexual selection to understand our... more This theoretical proposal applies evolutionary aesthetic, animal signalling and sexual selection to understand our artistic cognition, especially rock art aesthetics. Iconographic motifs, universally found in rock art, indicate which set of pre-artistic aesthetic psychological bias has been co-opted to catch the viewer’s attention. The co-evolutionary process of sexual selection could have shaped the design features of both rock art images and their aesthetic cognition by conferring mutual benefits on both producers, via manipulation, and receivers, via information extraction. We show some strategic techniques identified in rock art and art that indicate the occurrence of this co-evolution between producers and receivers.

Approaches, concepts, universalities and sexual selection on the evolution of palaeoart appreciation. Commentary. Authors' reply

by Marco Varella

Egg testosterone affects wattle color and trait covariation in the ring-necked pheasant

by Andrea Bonisoli-Alquati

Incipient sexual isolation in Laupala cerasina: females discriminate population-level divergence in acoustic characters

by Jaime Grace

Uncorrected proof, will appear in a special column of Current Zoology, guest edited by Maria Servedio, with theme "Sexual selection and speciation". Coauthored with my Ph.D. advisor, Kerry Shaw. I have just received the proofs and the paper will be published in the June issue, 2012

Sexual selection by female choice can shape the evolution of male traits within populations, since the most attractive... more Sexual selection by female choice can shape the evolution of male traits within populations, since the most attractive males experience an increase in fitness through elevated mating success. Speciation by sexual selection occurs when evolution in traits and preferences within populations causes differentiation among populations, such that females in alternative populations prefer sexual signals of their own population relative to others. Differentiated traits and preferences thereby play an active role in limiting gene flow between divergent populations. The effectiveness of differentiated preferences in maintaining differentiated male signals against the homogenizing effects of gene flow across populations will be limited by both the degree to which females can discriminate against non-local males, and the breeding values of traits and preferences. Populations of the Hawaiian cricket Laupala cerasina have diverged in pulse rate, a sexually selected male signal, and female acoustic preference for pulse rate. Gene flow between neighboring populations may be reduced if migrants from sexually diverged populations experience reduced mating success. We show that females discriminate among divergent songs characteristic of neighboring populations, that differences among populations in song and preference breed true in a common environment, and that mean preferences for each population closely match the mean pulse rates. Divergence in preference was observed only between populations that also differed in song. Along with a striking ability to discriminate slight differences in song, correlated evolution of song and preference within populations could be a mechanism that promotes assortative mating among populations, thereby reducing gene flow, and leading to speciation in Laupala.

Reproductive selection and human evolution: An empirical analysis for Spain, 2010

by Diego Varela

Working paper.

In this paper I investigate whether there is an economic bias in the reproduction of humans in Spain using data from... more In this paper I investigate whether there is an economic bias in the reproduction of humans in Spain using data from the Encuesta de Presupuestos Familiares (Household Budget Survey) of 2010. The main result is that parents that are income earners tend to earn 16% more than other income earners of equal age and gender. Parents also have greater probability of being income earners than the rest of the population of equal age and gender. I argue that the contribution of such reproductive selection to economic development can be as high as half a percentage point per year.