Visual effects in great bowerbird sexual displays and their implications for signal design

It is often assumed that the primary purpose of a male's sexual display is to provide information about quality, or to strongly stimulate prospective mates, but other functions of courtship displays have been relatively neglected. Male great bowerbirds (Ptilonorhynchus nuchalis) construct bowers that exploit the female's predictable field of view (FOV) during courtship displays by creating forced perspective illusions, and the quality of illusion is a good predictor of mating success. Here, we present and discuss two additional components of male courtship displays that use the female's predetermined viewpoint: (i) the rapid and diverse flashing of coloured objects within her FOV and (ii) chromatic adaptation of the female's eyes that alters her perception of the colour of the displayed objects. Neither is directly related to mating success, but both are likely to increase signal efficacy, and may also be associated with attracting and holding the female's attention. Signal efficacy is constrained by trade-offs between the signal components; there are both positive and negative interactions within multicomponent signals. Important signal components may have a threshold effect on fitness rather than the often assumed linear relationship.

Artificial selection for food colour preferences

Colour is an important factor in food detection and acquisition by animals using visually based foraging. Colour can be used to identify the suitability of a food source or improve the efficiency of food detection, and can even be linked to mate choice. Food colour preferences are known to exist, but whether these preferences are heritable and how these preferences evolve is unknown. Using the freshwater fish Poecilia reticulata, we artificially selected for chase behaviour towards two different-coloured moving stimuli: red and blue spots. A response to selection was only seen for chase behaviours towards the red, with realized heritabilities ranging from 0.25 to 0.30. Despite intense selection, no significant chase response was recorded for the blue-selected lines. This lack of response may be due to the motion-detection mechanism in the guppy visual system and may have novel implications for the evolvability of responses to colour-related signals. The behavioural response to several colours after five generations of selection suggests that the colour opponency system of the fish may regulate the response to selection.

Variable environmental effects on a multicomponent sexually selected trait

Multicomponent signals are made up of interacting elements that generate a functional signaling unit. The interactions between signal components and their effects on individual fitness are not well understood, and the effect of environment is even less so. It is usually assumed that color patterns appear the same in all light environments and that the effects of each color are additive. Using guppies, Poecilia reticulata, we investigated the effect of water color on the interactions between components of sexually selected male coloration. Through behavioral mate choice trials in four different water colors, we estimated the attractiveness of male color patterns, using multivariate fitness estimates and overall signal contrast. Our results show that females exhibit preferences that favor groups of colors rather than individual colors independently and that each environment favors different color combinations. We found that these effects are consistent with female guppies selecting entire color patterns on the basis of overall visual contrast. This suggests that both individuals and populations inhabiting different light environments will be subject to divergent, multivariate selection. Although the appearance of color patterns changes with light environment, achromatic components change little, suggesting that these could function in species recognition or other aspects of communication that must work across environments. Consequently, we predict different phylogenetic patterns between chromatic and achromatic signals within the same clades.

Noisy neighbours at the frog pond: effects of invasive cane toads on the calling behaviour of native Australian frogs

Invasive species can disrupt the communication systems that native biota use for reproductive interactions. In tropical Australia, invasive cane toads (Rhinella marina) breed in many of the same waterbodies that are used by native frogs, and males of both the invader and the native taxa rely on vocal signals to attract mates. We conducted playback experiments to test the hypothesis that calls of toads may influence the calling behaviour of frogs (Limnodynastes convexiusculus and Litoria rothii). Male L. convexiusculus adjusted their calling rate and the variance in inter-call interval in response to a variety of sounds, including the calls of cane toads as well as those of other native frog species, and other anthropogenic noise, whereas L. rothii did not. Within the stimulus periods of playbacks, male L. convexiusculus called more intensely during long silent gaps than during calling blocks. Thus, males of one frog species reduced their calling rate, possibly to minimise energy expenditure during periods of acoustic interference generated by cane toads. In spite of such modifications, the number of overlapping calls (within stimulus periods) did not differ significantly from that expected by chance. In natural conditions, the calls of cane toads are continuous rather than episodic, leaving fewer gaps of silence that male frogs could exploit. Future work could usefully quantify the magnitude of temporal (e.g. diel and seasonal) and spatial overlap between calling by toads and by frogs and the impact of call-structure shifts on the ability of male frogs to attract receptive females.

The more pieces, the better the puzzle: sperm concentration increases gametic compatibility

The genetic benefits individuals receive from mate choice have been the focus of numerous studies, with several showing support for both intrinsic genetic benefits and compatibility effects on fertilization success and offspring viability. However, the robustness of these effects have rarely been tested across an ecologically relevant environmental gradient. In particular, sperm environment is a crucial factor determining fertilization success in many species, especially those with external fertilization. Here, we test the importance of sperm environment in mediating compatibility-based selection on fertilization using a factorial breeding design. We detected a significant intrinsic male effect on fertilization success at only one of four sperm concentrations. Compatibility effects were significant at the two highest sperm concentrations and, interestingly, the magnitude of the compatibility effect consistently increased with sperm concentration. This suggests that females are able to modify the probability of sperm-egg fusion as the amount of sperm available increases.

Assortative mating among animals of captive and wild origin following experimental conservation releases

Captive breeding is a high profile management tool used for conserving threatened species. However, the inevitable consequence of generations in captivity is broad scale and often-rapid phenotypic divergence between captive and wild individuals, through environmental differences and genetic processes. Although poorly understood, mate choice preference is one of the changes that may occur in captivity that could have important implications for the reintroduction success of captive-bred animals. We bred wild-caught house mice for three generations to examine mating patterns and reproductive outcomes when these animals were simultaneously released into multiple outdoor enclosures with wild conspecifics. At release, there were significant differences in phenotypic (e.g. body mass) and genetic measures (e.g. Gst and F) between captive-bred and wild adult mice. Furthermore, 83% of offspring produced post-release were of same source parentage, inferring pronounced assortative mating. Our findings suggest that captive breeding may affect mating preferences, with potentially adverse implications for the success of threatened species reintroduction programmes.

Male and female interactions during courtship of the Neotropical damselfly Mnesarete pudica (Odonata: Calopterygidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Escolha de parceiros na adolescência

Mate choice is a component of sexual selection. Trying to understand the patterns of this process, several studies have emphasized the adaptive value of sexual differences and their influence on the assessment of the market value. The pattern for adults presented on the scientific literature, which is based on the preference for certain characteristics, shows that men search a partner who shows high value of fecundity and fertility, thus looking for partners with the ability of being pregnant and nursing their offspring. On the other hand, women look for partners with high socioeconomic status, which is strongly associated with the ability to protect and provide resources for them and their offspring. Surprisingly, there is few works that investigated the mate choice patterns during the beginning of the period of sexual differentiation on the morphological, physiological and behavioral traits. The aim of this study was to investigate mate choice patterns in adolescence in order to describe their preferences and contribute to the understanding of human reproductive behavior. Took part of this research 1,232 students from educational institutions of Natal, Brazil, and visitors to the Scientific, Technological and Cultural Fair UFRN. In the Experimental Study 1, we applied a questionnaire to evaluate the importance of certain characteristics, assessed the degree of romantic involvement and real and ideal partners age preference. In the Experimental Study 2, we did a survey of characteristics considered relevant and evaluate the importance of these characteristics in mate choice. The Experimental Study 3 brought an investigation of mate choice patterns based on self-assessment of adolescents, evaluating ideal partner for a short-term and long-term relationships and actual partner. We found that adolescents are motivated to live romantic experiences. We also observed a preference for partners of similar age to that described for adults. Finally, we found similarities and differences in the preferences for characteristics in real and ideal partners in relation to the adult pattern. In addition, we observed high similarity on the self-assessment and assessment of real and ideal partners. We suggest that in the mate choice, adolescents are similar to young adults in some aspects but not all. Our results show the relevance of the reproductive behavior investigation in this human developmental period and reinforce that further studies should contribute to the understanding of human behavior in terms of ontogenetic development and their evolutionary history.

Papel de sinais cromáticos na identificação de parceiros sexuais em sagüi comum (callithrix jacchus)

The literature concerning color vision shows a trichromatic advantage in detecting ripe fruits and young leaves, but there are contradictory results. There is also the suggestion of this type of vision being adapted to perceive socio-sexual signals. Indeed, Old World primates utilize the skin color of conspecifics as a factor of attraction. But in New World primates there is no record of a coloration signal in the body that can be utilized by other group members. The present study aims to: 1- test whether there is a relation between coloration of body regions and ovulatory cycle in female Callithrix jacchus; 2- Determine if this species uses visual signals to choose mates that are sexually receptive. We collected feces from six females during one month to quantify progesterone concentration by EIA. Body region coloration was measured using a portable spectrometer and modeled to obtain the quantum catch of each photoreceptor, the opponency channels and chromatic distance between the points in units of JND. We recorded the behavior of six males exposed to three pairs of females with a cycling and a non-cycling female in each pair using a transparent plexiglass apparatus. The color of different body regions presented a correlation between progesterone concentration and the yellow-blue and red-green visual axes, with the genitalia as the region showing the highest correlation. The visual axis more apt to see the color variations was the yellow-blue in dichromats, and in trichromats were the red-green to face, yellow-blue to abdomen and both chromatic axes to genitalia. There was no difference in the signal detectability between trichromats and dichromats, but the perception pattern differed between the phenotypes, with a better signal detection by the dichromat phenotype 562 and the trichromat phenotype 543/562. During the behavioral experiments males presented longer gaze duration in periods of experimental manipulation and gaze duration was always longer towards cycling females compared to non-cycling females. Male locomotion during experimental manipulation was greater than in the control only during the periovulatory period of the female, indicating greater excitement. The behavior of cycling females was more active than the behavior of the non-cycling ones regarding locomotion and touching of the plexiglass division of the apparatus. Male gaze duration to cycling females increased with decreasing progesterone concentration, but none of the coloration parameters was correlated to the mate preference exhibited. This coloration signal can transmit information to animals of the group about fertility of female. Different from the intense red of the genitalia swellings of Old World primates, marmoset female genitalia became more bluish-green in the fertile period. Males chose fertile females and were able to visually identify the periovulatory period of females. Choice is related to progesterone concentration, but our results do not show relation between coloration and mate preference. Maybe some behavioral measure is associated with the choice

Female preferences based on male nutritional chemical traits

Selection favors females that attend to reliable information about male genetic quality and fitness. Male nutritional condition can be a significant sign of mate quality since poor nutrition can be related to reduced sperm quality, low sperm quantity, sexually transmitted diseases, and parasites. We tested whether female Nile tilapia, Oreochromis niloticus, preferred the chemical cues of males that were well fed with high-protein diet over those fed with low-protein diet. Females do not only discriminate between males but also show a preference for well-fed males, discriminating between the odors with respect to nutritional state, suggesting that they were responding to a food-specific chemical cue. It is therefore likely that nutritional condition is related to the production of pheromones in males. Our results suggest that information about male nutritional state can be conveyed in chemical cues and that females attend to these cues during mate choice.

Efeito do contato macho-fêmea na preferência da fêmea e na competição entre machos na tilápia-do-Nilo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Critérios utilizados na seleção de parceiras amorosas em relacionamentos de curto e longo prazo entre mulheres de orientação homossexual em idade reprodutiva

Diferentes critérios utilizados para a escolha de parceiros entre homens e mulheres têm sido identificados. Essa diferença, provavelmente, origina-se pelos diferentes graus de investimento parental entre gêneros. Mulheres parecem ter predisposição a selecionar parceiros com características de investimento emocional, material e com bons indicativos de saúde. Já homens podem utilizar os mesmos critérios que as mulheres, porém dão mais importância que estas à aparência física e juventude. Em relacionamentos de curto e longo prazo a literatura indica que há uma diferença nas escolhas entre mulheres. No primeiro caso, elas têm demonstrando preferir características relacionadas à saúde física, comparado ao segundo tipo de relacionamento, no qual a ênfase tem sido voltada à parceiros bons provedores de recursos e com alto nível de investimento emocional. Há poucas pesquisas que investigaram os critérios que mulheres homossexuais utilizam na escolha de suas parceiras amorosas. Estudos que investigaram a origem da homossexualidade apontaram a possibilidade de influências biológicas. Em termos evolutivos, a homossexualidade poderia ter surgido, em parte, como subproduto da evolução do prazer característico das atividades sexuais. Se esta hipótese estiver correta, o potencial para o desenvolvimento de uma orientação homo, hetero ou bissexual pode ser potencializado por ambientes característicos dos indivíduos em particular. Tal hipótese pode sugerir que os mecanismos psicológicos para escolha de parceiros sejam semelhantes entre as mulheres de variadas orientações sexuais. Para testar esta hipótese, investigou-se as preferências na escolha de parceiras de 100 mulheres em período reprodutivo, entre 18 e 40 anos, que se auto-classificaram como “homossexual exclusivo” ou “homossexual, e às vezes heterossexual”. Para a coleta de dados foram utilizados dois instrumentos, um para seleção das participantes e outro para a coleta de informações. O instrumento de coleta de dados foi dividido em: 1) Dados Demográficos; 2) Dados da parceira; 3) Critérios valorizados na escolha de uma parceira; 4) Critérios valorizados na escolha de uma parceira de curto e longo prazo; 5) Variáveis relacionadas ao desempenho sexual. As participantes foram contatadas pelo método a) “snow ball”, b) bares frequentados por grupos homossexuais e c) associações GLBT. Especificamente, investigou-se as variáveis envolvidas na escolha de parceiras de curto e longo prazo e comparou-se os resultados com os dados coletados por Cruz (2009), com mulheres heterossexuais em período reprodutivo. Os resultados indicaram que há maior preferência por atributos físicos em relacionamentos de curto prazo entre mulheres homo e heterossexuais. Atributos referentes à formação de vínculo foram mais solicitados em relacionamentos de longo prazo, possivelmente porque 75,6% dessas mulheres têm renda e não dependem do parceiro(a) para o provimento na relação, diminuindo a necessidade de parceiro(a)s que invistam recursos materiais. Mulheres homossexuais parecem ter os mesmos padrões de escolha de parceiros que heterossexuais.

Caracterização molecular de genes do sistema imune de búfalo

Pós-graduação em Genética e Melhoramento Animal - FCAV

Homogamy preferences for cognitive sex-typicality in women

Homogamy has been suggested as crucial for human mate preferences and mate choice. People are attracted to and choose romantic partners that are similar to them in socio-demographic, physical, and psychological traits. However, only a few studies have shown homogamy in preferences for evolved sex-typical traits. Here, we have investigated male and female preferences for the level of cognitive masculinity-femininity (MF). We tested whether self-reported MF positively correlates with preferences for MF. One hundred men and one hundred women from Brazil filled in questionnaires on their own level of cognitive MF and preferred level of cognitive MF in their ideal partner. Half of the respondents were asked to indicate their preferences for long-term, and the other half for short-term relationships. We found a positive correlation between self-ascribed and preferred level of cognitive MF in women (P = 0.002), but no significant correlation in men (P = 0.309). There was no significant effect of the temporal context of the relationship, but there was a positive correlation between self-ascribed and preferred level of cognitive MF only in women answering about long-term partner. By subtracting the preferred from the selfascribed level of cognitive MF, we created a self-similarity index. We found that women desire potential mates more self-similar and more masculine than men (P < 0.001) and that in men there is greater variation in the self-similarity index than in women. Our results thus add to previous evidence on the role of homogamy in human mating, by showing preferences for self-similarity also in cognitive MF for women, especially for long-term partner preferences. Future studies should cross-culturally test whether the higher self-similar preference found in women is universal.

Influência da infecção por patógenos na escolha química de parceiros em tilápia-do-Nilo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)