Evolutionary biologists have developed several indices, such as selection gradients (β) and the opportunity for sexual (Is), to quantify actual and/or potential strength of acting in natural or experimental populations. In a recent paper, Klug et al. (J. Evol. Biol.23, 2010, 447) contend that are only legitimate metric quantifying selection. They argue Is similar mating-system-based metrics provide unpredictable results, which may be uncorrelated with on trait, should therefore abandoned. We...

Competition among males for access to reproductive opportunities is a central tenet of behavioural biology that has critical implications studies mating systems, sexual selection and the evolution numerous phenotypic traits. Given expectation should compete vigorously females, it may at first seem paradoxical in some species cooperate reproduce, often resulting apparent sacrifice direct fitness by members these cooperative partnerships. Because this form cooperation lies interface between...

Male lance-tailed manakins (Chiroxiphia lanceolata) cooperate in complex courtship displays, but the dominant (alpha) partner monopolizes mating opportunities. This raises question of why subordinates (betas) cooperate. Three nonexclusive hypotheses explain adaptive basis helping behavior by subordinate males: cooperation may increase (1) subordinates' immediate reproductive success, (2) success close relatives, or (3) chances future reproduction. I demonstrated that beta males rarely sired...

Leks are classic models for studies of sexual selection due to extreme variance in male reproductive success, but the relative influence intrasexual competition and female mate choice creating this skew is debatable. In lekking lance-tailed manakin (Chiroxiphia lanceolata), these selective episodes temporally separated into alpha status among males that rarely interact. Variance success between classes adult (alpha versus non-alpha) can therefore be attributed male-male whereas within...

Male Lance-tailed Manakins (Chiroxiphia lanceolata) perform multi-male courtship displays for females. To characterize the behavioral repertoire and lek spatial organization of this species, I observed lekking males on Isla Boca Brava, Chiriquí Province, Panamá. Breeding began in March continued through June, though were recorded as late November. Males active throughout day at display areas dispersed lek. Display spaced 102 ± 30 m apart averaged 2,480 1,060 m2 area (range: 525–4,500 m2; n =...

Social learning about mate choices is taxonomically widespread, and a potentially important mechanism of social evolution that may affect the strength sexual selection in population. We used meta-analytic approach to estimate effect mate-choice copying on reproductive decisions. evaluated sizes across 103 experiments from 40 studies experimentally measured female non-human animals representing Arachnida, Insecta, Malacostraca, Aves, Actinoperygii. Our goals were quantify magnitude this form...

Sexual selection by mate choice is a powerful force that can lead to evolutionary change, and models of why females choose particular mates are central understanding its effects. Predominant theories assume preferences determined solely genetic inheritance, an assumption still lacking widespread support. Moreover, often vary among individuals or populations, fail correspond with conspicuous male traits, change context, patterns not predicted dominant models. Here, we propose new model...

The causes of variation in individual reproductive success over a lifetime are not well understood. In long-lived vertebrates, output usually increases during early adulthood, but it is difficult to disentangle the roles development and learning on this gain success. Lekking lance-tailed manakins provide an opportunity separate these processes, as vast majority male reproduction occurs after bird obtains alpha status maintains display area lek, age at which males achieve varies widely. Using...

Great-tailed grackles (Quiscalus mexicanus) are sexually dimorphic, dichromatic, colonially nesting blackbirds. In this study, males pursued three basic types of conditional mating strategies, each which employed a different set tactics. Territorial defended one or more trees in several females nested. They achieved reproductive success by siring the offspring their social mates and through extrapair fertilization. Resident lived colony but did not defend territories have mates. Transient...

Abstract Male Lance-tailed Manakins (Chiroxiphia lanceolata) perform multi-male courtship displays for females. To characterize the behavioral repertoire and lek spatial organization of this species, I observed lekking males on Isla Boca Brava, Chiriquí Province, Panamá. Breeding began in March continued through June, though were recorded as late November. Males active throughout day at display areas dispersed lek. Display spaced 102 ± 30 m apart averaged 2,480 1,060 m2 area (range:...

Indirect benefits of mate choice result from increased offspring genetic quality and may be important drivers female behaviour. 'Good-genes-for-viability' models predict that females prefer mates high additive value, such survival should correlate with male attractiveness. Mate also vary diversity (e.g. heterozygosity) or compatibility relatedness), where the female's genotype influences choice. The relative importance these nonexclusive hypotheses remains unclear. Leks offer an excellent...

The differential allocation hypothesis predicts increased investment in offspring when females mate with high-quality males. Few studies have tested whether varies relatedness, despite evidence that non-additive gene action influences and genetic quality. We female lekking lance-tailed manakins ( Chiroxiphia lanceolata ) adjust sex egg volume response to attractiveness (annual reproductive success, ARS), heterozygosity relatedness. Across 968 offspring, the probability of being male...

Summary Experience improves individual performance in many tasks. Pre‐breeding cooperation may provide important experience that later success as a breeder, offering one compelling explanation for why some individuals delay reproduction to help others breed (the ‘skills hypothesis’). However, confounding effects of age, quality and alternative selective benefits have complicated rigorous tests this hypothesis. Male lance‐tailed manakins perform cooperative courtship displays involving...

I investigated the relationship of plumage to age and sex in Lance-tailed Manakin (Pipridae, Chiroxiphia lanceolata) lowlands western Panama from 1999–2004. captured birds mist nets, categorized their plumages, examined them for molt, followed several years document changes. Male Manakins exhibited three distinct postjuvenal plumages. Males achieved definitive adult through sequential changes that occurred same order as other manakins. Definitive male developed over time span reported C....

The extent and importance of female mate fidelity in polygynous mating systems are poorly known. Fidelity may contribute to high variance male reproductive success when it favors attractive mates or stabilize social interactions if females faithful sites rather than males. Using 12 years data on genetic choice the cooperatively lekking lance-tailed manakin (Chiroxiphia lanceolata), I investigated frequency within between years, whether were individual males across favored Mate occurred 41.7%...

Why do females faced with the same array of potential mates often select different males? Variation in choosiness, defined as investment mate search, is an important source variation mating decisions. Experimental work suggests such driven by costs searching, but data from natural populations are scarce and few studies have addressed explicitly counteracting benefits expected search investment. We tracked male visitation behavior free-ranging on a lek lance-tailed manakins (Chiroxiphia...

Investigation of the ecological and evolutionary basis for often-intriguing courtship behavior animals requires that we understand patterns variation inherent in such behaviors. The displays White-ruffed Manakin (Corapipo altera) are not well-known, previously published descriptions interpretations conflict with one another. We studied reproductive C. altera during 6 breeding seasons, observing 72 display courts (mean 29 ± 2.5 annually) a total 2688 hr. updated behavioral characterization by...

Abstract A biased adult sex ratio (ASR) can influence cooperative breeding behavior if the bias limits mating opportunities for more abundant sex. We tested predictions associated with ASR-cooperation hypothesis in brown-headed nuthatch (Sitta pusilla). manipulated ASR by cross-fostering known-sex nestlings within 2 large (≥100 ha) experimental plots 5 years using a crossover design where each plot received an opposing male- or female-biased treatment consecutive years. year no manipulations...

ABSTRACT Laughing falcon ( Herpetotheres cachinnans ) predation on coral snakes Micrurus nigrocinctus was recorded in two incidents that illustrate previously unreported variation predatory behavior. In the first, held a live snake by posterior end for an extended period of time, rather than decapitating it immediately. second, left decapitated tree more 2 h before returning to recover its prey. A variety behavioral adaptations may protect laughing falcons from venom.