Bills as daggers? A test for sexually dimorphic weapons in a lekking hummingbird

Rico‐Guevara, Alejandro; Araya‐Salas, Marcelo

doi:10.1093/beheco/aru182

Cited by 57 publications

(62 citation statements)

References 67 publications

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“…However, this scenario stands at odds with what we know about the territory acquisition process in long-billed hermits. Juveniles typically move from lek to lek competing with established males until they finally take ownership of a territory [22], and the likelihood of becoming territorial is determined in part by foraging efficiency, body size and weapon size (elongated bill tips used to stab opponents [50]) relative to other males in a lek [51]. Overall, the evidence suggests that variation in visual display structure does not play a major role when establishing a lek territory.…”

Section: Discussionmentioning

confidence: 98%

Social group signatures in hummingbird displays provide evidence of co-occurrence of vocal and visual learning

et al. 2019

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Vocal learning, in which animals modify their vocalizations based on social experience, has evolved in several lineages of mammals and birds, including humans. Despite much attention, the question of how this key cognitive trait has evolved remains unanswered. The motor theory for the origin of vocal learning posits that neural centres specialized for vocal learning arose from adjacent areas in the brain devoted to general motor learning. One prediction of this hypothesis is that visual displays that rely on complex motor patterns may also be learned in taxa with vocal learning. While learning of both spoken and gestural languages is well documented in humans, the occurrence of learned visual displays has rarely been examined in non-human animals. We tested for geographical variation consistent with learning of visual displays in long-billed hermits ( Phaethornis longirostris ), a lek-mating hummingbird that, like humans, has both learned vocalizations and elaborate visual displays. We found lek-level signatures in both vocal parameters and visual display features, including display element proportions, sequence syntax and fine-scale parameters of elements. This variation was not associated with genetic differentiation between leks. In the absence of genetic differences, geographical variation in vocal signals at small scales is most parsimoniously attributed to learning, suggesting a significant role of social learning in visual display ontogeny. The co-occurrence of learning in vocal and visual displays would be consistent with a parallel evolution of these two signal modalities in this species.

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Section: Discussionmentioning

confidence: 98%

Social group signatures in hummingbird displays provide evidence of co-occurrence of vocal and visual learning

et al. 2019

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“…Interspecific competition may be most intense among individuals of related species, species with similar morphological characteristics (associated with resource acquisition), or when a species is more massive than co‐occurring species at a feeder. Relatedness is often used a surrogate for competition due to increased niche overlap and differences in body size may predict the outcome of direct interactions, as less massive birds may be wary of interacting with more massive birds due to threat of injury (Feinsinger and Colwell , Rico‐Guevara and Araya‐Salas ).…”

Section: Introductionmentioning

confidence: 99%

Evaluating broad scale patterns among related species using resource experiments in tropical hummingbirds

Graham

2016

Ecology

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A challenge in community ecology is connecting biogeographic patterns with local scale observations. In Neotropical hummingbirds, closely related species often co-occur less frequently than expected (overdispersion) when compared to a regional species pool. While this pattern has been attributed to interspecific competition, it is important to connect these findings with local scale mechanisms of coexistence. We measured the importance of the presence of competitors and the availability of resources on selectivity at experimental feeders for Andean hummingbirds along a wide elevation gradient. Selectivity was measured as the time a bird fed at a feeder with a high sucrose concentration when presented with feeders of both low and high sucrose concentrations. Resource selection was measured using time-lapse cameras to identity which floral resources were used by each hummingbird species. We found that the increased abundance of preferred resources surrounding the feeder best explained increased species selectivity, and that related hummingbirds with similar morphology chose similar floral resources. We did not find strong support for direct agonism based on differences in body size or phylogenetic relatedness in predicting selectivity. These results suggest closely related hummingbird species have overlapping resource niches, and that the intensity of interspecific competition is related to the abundance of those preferred resources. If these competitive interactions have negative demographic effects, our results could help explain the pattern of phylogenetic overdispersion observed at regional scales.

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“…In nectar‐feeding birds, ISWs come as modifications of the bill tips to stab and pluck feathers (e.g. Rico‐Guevara & Araya‐Salas, ; Rico‐Guevara & Rubega, ; A. Rico‐Guevara, personal observations), however, bill tip shape is finely tuned to interact with the tongue in order to optimize nectar extraction efficiency (Rico‐Guevara & Rubega, ; Rico‐Guevara, Fan & Rubega, ; Rico‐Guevara, ). Hence, even ISWs that are not exaggerated structures (such as in spiders and salmon) can have an impact on the naturally selected function of the modified trait.…”

Section: Resultsmentioning

confidence: 99%

“…deer (Clutton‐Brock et al, ; Vanpe et al, ; beetles, Hongo, )], ( ii ) the most likely to maintain access to females [e.g. thrips (Crespi, ); wetas (Kelly, ); hummingbirds (Rico‐Guevara & Araya‐Salas, )], and ( iii ) generally the animals that achieve the highest fertilization success [e.g. spiders (Funke & Huber, ); red deer Cervus elaphus (Kruuk et al, )].…”

Section: Resultsmentioning

confidence: 99%

“…For example, an ISW can be fixed first through male-male competition and then the secondary sex trait could be boosted by intersexual resource partitioning, or interspecific dominance over critical resources [e.g. straighter and pointier bills in hummingbirds (Temeles, Miller & Rifkin, 2010;Rico-Guevara & Araya-Salas, 2015)]. Further studies on the influence of ISWs in interspecific antagonistic interactions (cf .…”

Section: (7) From Sexually Dimorphic Traits To Iswsmentioning

confidence: 99%

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Intrasexually selected weapons

2018

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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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Bills as daggers? A test for sexually dimorphic weapons in a lekking hummingbird

Cited by 57 publications

References 67 publications

Social group signatures in hummingbird displays provide evidence of co-occurrence of vocal and visual learning

Social group signatures in hummingbird displays provide evidence of co-occurrence of vocal and visual learning

Evaluating broad scale patterns among related species using resource experiments in tropical hummingbirds

Intrasexually selected weapons

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