Female, but Not Male, Tropical Sparrows Respond More Strongly to the Local Song Dialect: Implications for Population Divergence

Danner, Julie E.; Danner, Raymond M.; Bonier, Frances; Martin, Paul R.; Small, Thomas W.; Moore, Ignacio T.

doi:10.1086/660283

Cited by 86 publications

(74 citation statements)

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“…Song is an essential component of both territorial defense [Moore et al, 2004a; Addis et al, 2010] and courtship [Danner et al, 2011] in rufous-collared sparrows, and this species was the first tropical vertebrate shown to exhibit seasonal neuroplasticity [Moore et al, 2004c]. The growth of the rufous-collared sparrow SCN occurs during the early breeding seasons, concurrent with increased singing behavior, and is similar to that described in higher latitude congeners that have been more extensively studied (e.g.…”

Section: Introductionmentioning

confidence: 98%

Testosterone Mediates Seasonal Growth of the Song Control Nuclei in a Tropical Bird

Small

Brenowitz²,

Wojtenek

et al. 2015

Brain Behav Evol

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In mid- to high-latitude songbirds, seasonal reproduction is stimulated by increasing day length accompanied by elevated plasma sex steroid levels, increased singing, and growth of the song control nuclei (SCN). Plasticity of the SCN and song behavior are primarily mediated by testosterone (T) and its metabolites in most species studied thus far. However, the majority of bird species are tropical and have less pronounced seasonal reproductive cycles. We have previously documented that equatorial rufous-collared sparrows (Zonotrichia capensis) exhibit seasonal neuroplasticity in the SCN. Manipulating T in these birds, however, did not alter singing behavior. In the current study, we investigated whether T mediates plasticity of the SCN in a similar manner to temperate songbirds. In the first experiment, we treated captive male birds with T or blank implants during the nonbreeding season. In a second experiment, we treated captive male birds with either blank implants, T-filled implants, T with flutamide (FLU; an androgen receptor antagonist) or T with FLU and 1,4,6-androstatriene-3,17-dione (ATD; an estrogen synthesis inhibitor) during the breeding season. In both experiments, the volumes of the brain areas high vocal center (HVC), Area X, and robust nucleus of the arcopallium (RA) were measured along with singing behavior. In summary, T stimulated growth of HVC and RA, and the combined effect of FLU and ATD reversed this effect in HVC. Area X was not affected by T treatment in either experiment. Neither T-treated birds nor controls sang in captivity during either experiment. Together, these data indicate that T mediates seasonal changes in the HVC and RA of both tropical and higher- latitude bird species even if the environmental signals differ. However, unlike most higher-latitude songbirds, we found no evidence that motivation to sing or growth of Area X are stimulated by T under captive conditions.

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Section: Introductionmentioning

confidence: 98%

Testosterone Mediates Seasonal Growth of the Song Control Nuclei in a Tropical Bird

Small

Brenowitz²,

Wojtenek

et al. 2015

Brain Behav Evol

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“…Typically we expect males to be less discriminating than females in their reactions to song, because of lower costs associated with false positives (Searcy and Brenowitz, 1988;Ratcliffe and Otter, 1996). Indeed, in two studies of sparrows in the same family as Darwin's finches (Emberizidae), females were seen to respond positively to a narrower range of song stimuli than did males (Searcy et al, 2002;Danner et al, 2011). We thus expect any discriminations males make among stimulus classes to also occur in females, whereas a lack of discrimination among song categories by males is less likely to tell us anything about how females would respond.…”

Section: Discussionmentioning

confidence: 98%

Ecological speciation in Darwin’s finches: Parsing the effects of magic traits

2013

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Many recent studies of ecological speciation have focused on "magic trait" scenarios, in which divergent selection on viability traits leads inextricably to corresponding divergence in mechanisms, especially mate recognition systems, that facilitate assortative mating. Speciation however may also proceed via other scenarios, such as when populations experience directly selected or random divergence in mate recognition systems. The relative contributions of magic trait versus other scenarios for speciation remain virtually unexplored. The present study aims to test the relative contribution of the magic trait scenario in the divergence of populations of the medium ground finch Geospiza fortis of Santa Cruz Island, Galapagos. First, we assess differences in G. fortis song between a northern population (Borrero Bay) and a southeastern population (El Garrapatero), differences that we propose (along with other within-island geographic song variations) have arisen via scenarios that do not involve a magic trait scenario. Pairwise comparisons of raw and composite (PC) song parameters, as well as discriminant functions analyses, reveal significant patterns of song divergence between sites. Second, we test the ability of territorial males at Borrero Bay to discriminate songs from the two sites. We find that G. fortis males can discriminate within-island song variants, responding more strongly to local than to "foreign" songs, along 3 raw and 1 composite response measures. Third, we compare these findings to prior data sets on song divergence and discrimination in Santa Cruz G. fortis. These comparisons suggest that song divergence and discrimination are shaped less strongly by geographic sources than by morphological (beak-related) sources. We thus argue that interpopulation song divergence and discrimination, fundamental elements of assortative mating in Darwin's finches, can be fostered in early stages of divergence under magic trait as well as alternative scenarios for speciation, but with more emphasis on the magic trait scenario, at least for this species on this island [Current Zoology 59 (1): [8][9][10][11][12][13][14][15][16][17][18][19] 2013].

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“…Studies in other species found a low discrimination ability between local and non-local playback stimuli in males, but a high discrimination ability in females [99, 100]. However, male and female European stonechats have been shown to respond more strongly to playback and decoys from their own than from foreign populations [77].…”

Section: Discussionmentioning

confidence: 99%

Testosterone, territorial response, and song in seasonally breeding tropical and temperate stonechats

Apfelbeck

Mortega

Flinks³

et al. 2017

BMC Evol Biol

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BackgroundTestosterone facilitates physiological, morphological, and behavioral changes required for breeding in male vertebrates. However, testosterone concentrations and the link between its seasonal changes and those in reproductive behaviors vary greatly among species. To better understand the impact of tropical and temperate environments and life history factors on this variation, we have compared testosterone, territorial behavior and song performance across sequential stages of the breeding season in males of 16 closely related taxa of East African tropical and West European temperate stonechats (Saxicola spp), which all breed during a short breeding season, but differ in migratory behavior, seasonal territory-acquisition and pace of life.ResultsWe found that generally, the profiles of testosterone and territorial behavior were similar across latitudes. African stonechats with a slow pace of life had equally high peak testosterone concentrations and responded as aggressively to an intruder as European stonechats with a fast pace of life. However, song performance at the beginning of the breeding season was lower in African than in European stonechats. The differences in song performance were not associated with variation in testosterone levels between tropical and temperate stonechats.ConclusionsThe results suggest a very similar role for testosterone as a mediator of high intensity territorial aggression during the fertile period of females in tropical and temperate stonechats, which all are highly seasonal, locally synchronous breeders. A potential explanation may be high risk of extra-pair copulations which has been associated with synchronous breeding. Interestingly, an association was not consistent for song performance. Our data suggest that song performance can be disassociated from peak testosterone levels depending on its role in breeding behavior. Despite similar testosterone levels, European males, which early in the breeding season acquire territories and mates, showed greater song performance than African stonechats, which maintain year-round territories and pair-bonds. Taken together, our study comparing related taxa of old world songbirds suggests that short breeding seasons may be a major selective force for high peak testosterone levels during breeding regardless of latitude and pace of life, but that particular behaviors, in our case song, can be uncoupled from peak testosterone levels.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-0944-9) contains supplementary material, which is available to authorized users.

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Female, but Not Male, Tropical Sparrows Respond More Strongly to the Local Song Dialect: Implications for Population Divergence

Cited by 86 publications

References 74 publications

Testosterone Mediates Seasonal Growth of the Song Control Nuclei in a Tropical Bird

Testosterone Mediates Seasonal Growth of the Song Control Nuclei in a Tropical Bird

Ecological speciation in Darwin’s finches: Parsing the effects of magic traits

Testosterone, territorial response, and song in seasonally breeding tropical and temperate stonechats

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