Acoustic discrimination of sympatric morphs in Darwin's finches: a behavioural mechanism for assortative mating?

Podos, Jeffrey

doi:10.1098/rstb.2009.0289

Cited by 54 publications

(55 citation statements)

References 52 publications

(91 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Experiments in the field have demonstrated that closely related species in the genus Geospiza living sympatrically can discriminate between each other on the basis of song in the absence of visual cues (5,6) and on the basis of morphology in the absence of acoustic cues or movement (7). Furthermore, discrimination between allopatric populations of the same species is possible when they differ in song (5,8,9) or morphology (7).…”

mentioning

confidence: 99%

Songs of Darwin's finches diverge when a new species enters the community

Grant

2010

Proc. Natl. Acad. Sci. U.S.A.

137

View full text Add to dashboard Cite

Bird species sing different songs and as a result rarely breed with each other. Species are not static but can shift in acoustic and morphological space, yet maintain their distinctiveness. Investigating such a situation in a community of Darwin's finches sheds light on the origin and maintenance of premating barriers between species. Explanations for songs divergence generally invoke morphological changes to the sound-producing apparatus, environmental changes influencing transmitting properties of song, avoidance of acoustical interference with other species, and random processes including copying errors. We investigated changes in songs of Geospiza fortis (medium ground finch) and Geospiza scandens (cactus ground finch) from 1978 to 2010 on Daphne Major Island, Galápa-gos. The habitat did not change significantly; however, the finch community changed. The socially aggressive congener Geospiza magnirostris (large ground finch), singing in the same frequency band (2-4 kHz), colonized Daphne in 1983 and increased in numbers. Temporal features of the songs of G. fortis and G. scandens, especially trill rate and song duration, diverged from G. magnirostris songs as it became increasingly common. Changes in song were not a passive consequence of a change in beak morphology. Instead they arose as a bias during song imprinting and production. Sons of both G. fortis and G. scandens sang faster songs than their respective fathers and thereby differed more from G. magnirostris in their songs than did their fathers. Divergence from an aversive or confusing stimulus during learning illustrates a "peak shift" that may be a common feature of song evolution and speciation. cultural evolution | premating barriers | sexual imprinting | hybridization | character displacement A ccounting for the origins, persistence, and ultimate extinction of species is one of the most challenging problems for evolutionary biologists. In most cases the divergence of species from a common ancestor happened a long time ago; therefore the process must be inferred from genetic differences between extant species, and the causes are rarely understood. The smaller are the differences between species, and the more recent is their divergence from a common ancestor, the greater is the potential for discovering how and why one species gives rise to two. There are several model systems for studying speciation across a broad taxonomic range of closely related species, from Drosophila flies

show abstract

mentioning

confidence: 99%

Songs of Darwin's finches diverge when a new species enters the community

Grant

2010

Proc. Natl. Acad. Sci. U.S.A.

137

View full text Add to dashboard Cite

show abstract

“…We here used the same playback stimuli from the geographic song discrimination component of Podos (2010). In brief, we identified high-quality versions of songs recorded during our 2004 and 2005 visits to Borrero Bay (see above for recording methods).…”

Section: Playback Stimulimentioning

confidence: 99%

“…We assumed that all of our Borrero Bay singers were smallmorphed, based on annotations taken during recording and also given that large-morphed birds at Borrero Bay are rare (Hendry et al, 2006). Following Podos (2010), and as with our analysis of geographical variation in song structure (see above), we accounted for the presumed small-morph bias in our Borrero Bay playback stimuli by restricting our selection of playback songs from El Garrapatero to small-morphed singers from that site. For each of 18 playback stimuli (2 sequences for each of the 9 subjects), we prepared a playback sequence consisting of 18 repetitions of each song, played every 10 s for 3 min.…”

Section: Playback Stimulimentioning

confidence: 99%

“…These data are evaluated, in the discussion section, together with prior analysis of (i) song variation between El Garrapatero and Academy Bay (Podos, 2007) and between beak-size morphs at El Garrapatero (Huber and Podos 2006), (ii) previously reported playback data with birds at El Garrapatero on song discrimination by site (Podos 2007, Podos 2010) and beak-size morph (Podos 2010), and (iii) reported genetic differences by site and morph (Huber et al, 2007, de Leon et al, 2011 song playback, and genetic data within and across Santa Cruz sites (Fig. 1, Huber and Podos, 2006;Hendry et al, 2006;Podos, 2007Podos, , 2010de Leon et al, 2010). These approaches together allow a first assessment of the relative contributions of magic trait versus alternative scenarios in finch speciation.…”

Section: Fig 1 Map Of Galápagos and Santa Cruz Island Showing The Tmentioning

confidence: 99%

“…Selection for transmission efficacy in either context (minimizing degradation, maximizing detectability) can be considered as adaptive and ecologically-driven, yet would not fall under the classic magic-trait scenario because evolutionary change in the vocal phenotype results from direct selection rather than emerging as a secondary correlate of divergent selection on viability traits. Random drift (including cultural evolution) No Between site (and morph) Grant 1996, Goodale andPodos 2010 The first two mechanisms are adaptive, resulting in song x ecology correlations, yet only the first corresponds to the classic magic trait scenario (Servedio et al 2011). Acoustic adaptation does not fit under the classic magic trait scenario because it is driven directly by local acoustic ecology, rather than as an indirect byproduct of selection on a correlated viability trait.…”

mentioning

confidence: 99%

See 2 more Smart Citations

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

2013

Self Cite

View full text Add to dashboard Cite

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].

show abstract