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Wheatcroft, David
Publications (10 of 10) Show all publications
Wheatcroft, D. & Qvarnström, A. (2017). Genetic divergence of early song discrimination between two young songbird species. NATURE ECOLOGY & EVOLUTION, 1(7), Article ID UNSP 0192.
Open this publication in new window or tab >>Genetic divergence of early song discrimination between two young songbird species
2017 (English)In: NATURE ECOLOGY & EVOLUTION, ISSN 2397-334X, Vol. 1, no 7, article id UNSP 0192Article in journal (Refereed) Published
Abstract [en]

Juvenile songbirds express species-specific song discrimination from an early age, which focuses learning onto the songs of their parental species. However, it remains unknown whether this early song discrimination is influenced by early social experience or maternal effects or whether it is instead largely genetically determined. We manipulated early social experience by swapping young embryos between the nests of two co-occurring songbird species-pied and collared flycatchers. We show that nestlings are more active in response to playbacks of conspecific songs, even when raised by adults from the other species, thus enabling us to reject social experience as the main determinant of early song discrimination. We then crossed the two species in captivity and showed that the song responses of hybrid nestlings do not depend on social experience or maternal species, implying genetic divergence of early song discrimination. Our results provide conclusive evidence that early song discrimination has a largely genetic component, which can stabilize reproductive isolation by reducing song learning across closely related species.

National Category
Genetics Zoology
Identifiers
urn:nbn:se:uu:diva-344538 (URN)10.1038/s41559-017-0192 (DOI)000417179000020 ()
Funder
Swedish Research CouncilThe Royal Swedish Academy of Sciences
Available from: 2018-03-07 Created: 2018-03-07 Last updated: 2018-03-07Bibliographically approved
Wheatcroft, D. & Qvarnström, A. (2017). Reproductive character displacement of female, but not male song discrimination in an avian hybrid zone. Evolution, 71(7), 1776-1786
Open this publication in new window or tab >>Reproductive character displacement of female, but not male song discrimination in an avian hybrid zone
2017 (English)In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 71, no 7, p. 1776-1786Article in journal (Refereed) Published
Abstract [en]

Divergence of male sexual signals and female preferences for those signals often maintains reproductive boundaries between closely related, co-occurring species. However, contrasting sources of selection, such as interspecific competition, can lead to weak divergence or even convergence of sexual signals in sympatry. When signals converge, assortative mating can be maintained if the mating preferences of females diverge in sympatry (reproductive character displacement; RCD), but there are few explicit examples. Pied flycatchers (Ficedula hypoleuca) are sympatric with collared flycatchers (F. albicollis) on the Baltic island of oland, where males from both species compete over nestboxes, their songs converge, and the two species occasionally hybridize. We compare song discrimination of male and female pied flycatchers on oland and in an allopatric population on the Swedish mainland. Using field choice trials, we show that male pied flycatchers respond similarly to the songs of both species in sympatry and allopatry, while female pied flycatchers express stronger discrimination against heterospecific songs in sympatry than in allopatry. These results are consistent with RCD of song discrimination of female pied flycatchers where they co-occur with collared flycatchers, which should maintain species assortative mating despite convergence of male sexual signals.

Place, publisher, year, edition, pages
WILEY, 2017
Keywords
Ficedula, reinforcement, reproductive character displacement, sexual signals, song discrimination, species recognition
National Category
Biological Sciences
Identifiers
urn:nbn:se:uu:diva-331248 (URN)10.1111/evo.13267 (DOI)000405888100004 ()28493350 (PubMedID)
Funder
Swedish Research CouncilThe Royal Swedish Academy of Sciences
Available from: 2017-10-24 Created: 2017-10-24 Last updated: 2017-10-24Bibliographically approved
Suzuki, T. N., Wheatcroft, D. & Griesser, M. (2017). Wild Birds Use an Ordering Rule to Decode Novel Call Sequences. Current Biology, 27(15), 2331-2336.e3
Open this publication in new window or tab >>Wild Birds Use an Ordering Rule to Decode Novel Call Sequences
2017 (English)In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 27, no 15, p. 2331-2336.e3Article in journal (Refereed) Published
Abstract [en]

The generative power of human language depends on grammatical rules, such as word ordering, that allow us to produce and comprehend even novel combinations of words [1-3]. Several species of birds and mammals produce sequences of calls [4-6], and, like words in human sentences, their order may influence receiver responses [7]. However, it is unknown whether animals use call ordering to extract meaning from truly novel sequences. Here, we use a novel experimental approach to test this in a wild bird species, the Japanese tit (Parus minor). Japanese tits are attracted to mobbing a predator when they hear conspecific alert and recruitment calls ordered as alert-recruitment sequences [7]. They also approach in response to recruitment calls of heterospecific individuals in mixed-species flocks [8, 9]. Using experimental playbacks, we assess their responses to artificial sequences in which their own alert calls are combined into different orderings with heterospecific recruitment calls. We find that Japanese tits respond similarly to mixed-species alert-recruitment call sequences and to their own alert-recruitment sequences. Importantly, however, tits rarely respond to mixed-species sequences in which the call order is reversed. Thus, Japanese tits extract a compound meaning from novel call sequences using an ordering rule. These results demonstrate a new parallel between animal communication systems and human language, opening new avenues for exploring the evolution of ordering rules and compositionality in animal vocal sequences.

Place, publisher, year, edition, pages
CELL PRESS, 2017
National Category
Zoology Ecology
Identifiers
urn:nbn:se:uu:diva-334045 (URN)10.1016/j.cub.2017.06.031 (DOI)000407034300028 ()28756952 (PubMedID)
Available from: 2017-11-21 Created: 2017-11-21 Last updated: 2017-11-21Bibliographically approved
Suzuki, T. N., Wheatcroft, D. & Griesser, M. (2016). Experimental evidence for compositional syntax in bird calls. Nature Communications, 7, Article ID 10986.
Open this publication in new window or tab >>Experimental evidence for compositional syntax in bird calls
2016 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 7, article id 10986Article in journal (Refereed) Published
Abstract [en]

Human language can express limitless meanings from a finite set of words based on combinatorial rules (i.e., compositional syntax). Although animal vocalizations may be comprised of different basic elements (notes), it remains unknown whether compositional syntax has also evolved in animals. Here we report the first experimental evidence for compositional syntax in a wild animal species, the Japanese great tit (Parus minor). Tits have over ten different notes in their vocal repertoire and use them either solely or in combination with other notes. Experiments reveal that receivers extract different meanings from 'ABC' (scan for danger) and 'D' notes (approach the caller), and a compound meaning from 'ABCD' combinations. However, receivers rarely scan and approach when note ordering is artificially reversed ('D-ABC'). Thus, compositional syntax is not unique to human language but may have evolved independently in animals as one of the basic mechanisms of information transmission.

National Category
Zoology
Identifiers
urn:nbn:se:uu:diva-283660 (URN)10.1038/ncomms10986 (DOI)000371726400001 ()26954097 (PubMedID)
Available from: 2016-04-14 Created: 2016-04-14 Last updated: 2017-11-30Bibliographically approved
Wheatcroft, D. & Qvarnström, A. (2015). A blueprint for vocal learning: auditory predispositions from brains genomes. Biology Letters, 11(8), Article ID 20150155.
Open this publication in new window or tab >>A blueprint for vocal learning: auditory predispositions from brains genomes
2015 (English)In: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 11, no 8, article id 20150155Article, review/survey (Refereed) Published
Abstract [en]

Memorizing and producing complex strings of sound are requirements for spoken human language. We share these behaviours with likely more than 4000 species of songbirds, making birds our primary model for studying the cognitive basis of vocal learning and, more generally, an important model for how memories are encoded in the brain. In songbirds, as in humans, the sounds that a juvenile learns later in life depend on auditory memories formed early in development. Experiments on a wide variety of songbird specie's suggest that the formation and lability of these auditory memories, in turn, depend on auditory predispositions that stimulate learning when a juvenile hears relevant, species-typical sounds. We review evidence that variation in key features of these auditory predispositions are determined by variation in genes underlying the development of the auditory system. We argue that increased investigation of the neuronal basis of auditory predispositions expressed early in life in conibination with modem comparative genomic approaches may provide insights into the evolution of vocal learning.

Keywords
auditory predispositions, bird song, memory formation, perceptual biases, songbirds, vocal learning
National Category
Biological Sciences
Identifiers
urn:nbn:se:uu:diva-267506 (URN)10.1098/rsbl.2015.0155 (DOI)000362798100008 ()
Available from: 2015-11-24 Created: 2015-11-24 Last updated: 2017-12-01Bibliographically approved
Hoglund, J., Saether, S. A., Fiske, P., Wheatcroft, D. & Kalas, J. A. (2015). A hybrid snipe Gallinago gallinago x G-media found in the wild. Journal of Ornithology = Journal fur Ornithologie, 156(3), 819-827
Open this publication in new window or tab >>A hybrid snipe Gallinago gallinago x G-media found in the wild
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2015 (English)In: Journal of Ornithology = Journal fur Ornithologie, ISSN 0021-8375, E-ISSN 1439-0361, Vol. 156, no 3, p. 819-827Article in journal (Refereed) Published
Abstract [en]

A hybrid snipe male was observed and caught in 2009 in the Norwegian mountains. We report behaviour, vocalizations, morphology, and genetic data for this bird. Mitochondrial and nuclear DNA sequences revealed that the hybrid had a great snipe mother and a common snipe father. The hybrid was intermediate in most measured morphometric traits and showed some intermediate plumage characteristics. The behaviour was similar to that of a great snipe-it displayed and vocalised at a great snipe lek for more than a week. The song was somewhat reminiscent of a great snipe's, but lacked the frequency-modulated whistles that are part of the great snipe song, consisting of more rapid click notes of a narrower frequency spectrum. This is the only putative hybrid that we have found among the more than 4,400 adult individuals we have examined between 1986 and 2014 at great snipe leks in Norway, Sweden, Poland, and Estonia. Common snipes invariably occur near these sites. Reports on putative hybrids among snipe species are very rare, and we question the validity of previous claims. This is the first where the parental origins-and, indeed, the hybrid status-have been unequivocally determined. We speculate on how a great snipe female, known for being extremely choosy about mating, came to mate with a common snipe male. We also note that, although perhaps behaviourally more likely, physical constraints on chick development (caused by the smaller egg size of the common snipe and larger body size of the great snipe) might prevent any successful male great snipe x female common snipe hybridisation-a possible example of an unidirectional post-zygotic barrier.

Keywords
Snipe, Hybrid, Behaviour, Morphometrics, Song, Post zygotic isolation
National Category
Biological Sciences
Identifiers
urn:nbn:se:uu:diva-258322 (URN)10.1007/s10336-015-1154-0 (DOI)000356447100026 ()
Funder
Swedish Research Council
Available from: 2015-07-15 Created: 2015-07-13 Last updated: 2017-12-04Bibliographically approved
Wheatcroft, D. & Price, T. D. (2015). Rates of signal evolution are associated with the nature of interspecific communication. Behavioral Ecology, 26(1), 83-90
Open this publication in new window or tab >>Rates of signal evolution are associated with the nature of interspecific communication
2015 (English)In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 26, no 1, p. 83-90Article in journal (Refereed) Published
Abstract [en]

Some signals vary greatly, whereas others are remarkably similar across distantly related species. Here, we ask how the suite of receivers and information communicated correlates with signal evolution by comparing 2 different signals across the same set of species. Within the Old World leaf warblers (Phylloscopidae), each species utters 2 acoustically distinct alarm calls. The first, termed a "general" call, is used in interactions with conspecifics as a well as during confrontations with predators and nest-parasitic cuckoos. The second, termed a "rasp" call, is primarily used in the presence of nest-parasitic cuckoos. The rasp call precedes aggressive attacks on cuckoos and attracts surrounding heterospecifics that are also potential hosts. The general call attracts a wide range of species threatened by predators, including those that are not cuckoo hosts. Acoustic features of general calls evolve >5x faster than rasp calls. We argue that rasp calls show strong stasis because they have a restricted function as aggressive antiparasite signals, whereas multiple contexts and receivers have promoted divergence in general calls. These results support the idea that variation in the suite of receivers is a powerful force affecting signal evolution.

Keywords
animal signals, brood parasitism, cuckoos, interspecific communication, Phylloscopus, rate tests
National Category
Ecology Zoology
Identifiers
urn:nbn:se:uu:diva-252044 (URN)10.1093/beheco/aru161 (DOI)000351929300013 ()
Available from: 2015-04-29 Created: 2015-04-28 Last updated: 2017-12-04Bibliographically approved
Wheatcroft, D. (2015). Repetition rate of calls used in multiple contexts communicates presence of predators to nestlings and adult birds. Animal Behaviour, 103, 35-44
Open this publication in new window or tab >>Repetition rate of calls used in multiple contexts communicates presence of predators to nestlings and adult birds
2015 (English)In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 103, p. 35-44Article in journal (Refereed) Published
Abstract [en]

In multispecies communities, animals may come to recognize the signals of other species both by responding to common signal features and by learning about associations between signals and relevant threats. However, some signals are produced in multiple contexts. To a given receiver, such a signal may only sometimes be relevant. Here, I demonstrate that receivers use contextual variation in signal form as a cue to their relevance. Individuals from 15 species of songbirds repeated their calls rapidly when confronting widely threatening predators, but repeated the same calls more slowly during other types of social interactions. In playback experiments, repetition rate was a cue to nestling Ficedula flycatchers, which reduced their activity in response to quickly but not slowly repeated calls, and also to adult birds from a variety of species, which responded more strongly to the calls of their own and other species produced at faster rates. These results show that repetition rate is an innate or early learned contextual cue and, in combination with learning about heterospecific signals, allows receivers to fine-tune their responses to the calls of their own and other species according to their relevance, suggesting that simple rules facilitate widespread heterospecific communication networks. (C) 2015 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Keywords
calls, Ficedula, interspecific communication, motivational, structural rules, passerine birds, repetition rate, vocal learning
National Category
Zoology
Identifiers
urn:nbn:se:uu:diva-304607 (URN)10.1016/j.anbehav.2015.02.009 (DOI)000353378200006 ()
Available from: 2016-10-06 Created: 2016-10-06 Last updated: 2017-11-30Bibliographically approved
Wheatcroft, D. (2015). Reproductive interference via display signals: the challenge of multiple receivers. Population Ecology, 57(2), 333-337
Open this publication in new window or tab >>Reproductive interference via display signals: the challenge of multiple receivers
2015 (English)In: Population Ecology, ISSN 1438-3896, E-ISSN 1438-390X, Vol. 57, no 2, p. 333-337Article in journal (Refereed) Published
Abstract [en]

Sexually selected traits important in both mate and competitor recognition provide an opportunity to understand the tradeoffs associated with reproductive and competitive interference. When co-occurring species compete over similar resources, selection may promote signal similarity to facilitate competitive interactions in opposition to selection for signal divergence to maintain assortative mating. Bird song provides a classic example of contrasting selection on signal design, because songs function both in mate discrimination and in territorial advertisement. Similarity in songs aids competitor recognition both within and across species, and song convergence or mixing is widespread in the songbirds. Two related mechanisms can maintain mate recognition in the face of song convergence. First, multiple recognition signals, both across and within signaling modalities, provide a basis for mate and competitor discrimination using different sets of cues. Second, stricter female song preferences may allow interspecific male-male competitive communication without compromising female mate discrimination. I suggest that increased understanding of the neurobiology underlying song recognition will provide insight into the relative importance and prevalence of these different mechanisms along a continuum of species divergence.

Keywords
Competitive interference, Evolutionary tradeoffs, Reproductive interference, Song, Sexually selected signals
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-258893 (URN)10.1007/s10144-015-0487-0 (DOI)000356776800008 ()
Available from: 2015-07-21 Created: 2015-07-21 Last updated: 2017-12-04Bibliographically approved
Wheatcroft, D. & Price, T. D. (2013). Learning and signal copying facilitate communication among bird species. Proceedings of the Royal Society of London. Biological Sciences, 280(1757), 20123070
Open this publication in new window or tab >>Learning and signal copying facilitate communication among bird species
2013 (English)In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 280, no 1757, p. 20123070-Article in journal (Refereed) Published
Abstract [en]

Signals relevant to different sets of receivers in different contexts create a conflict for signal design. A classic example is vocal alarm signals, often used both during intraspecific and interspecific interactions. How can signals alert individuals from a variety of other species in some contexts, while also maintaining efficient communication among conspecifics? We studied heterospecific responses to avian alarm signals that drive the formation of anti-predator groups but are also used during intraspecific interactions. In three species-rich communities in the western Himalayas, alarm signals vary drastically across species. We show that, independently of differences in their calls, birds respond strongly to the alarm signals of other species with which they co-occur and much more weakly to those of species with which they do not co-occur. These results suggest that previous exposure and learning maintain heterospecific responses in the face of widespread signal divergence. At an area where only two species regularly interact, one species' calls incorporate the call of the other. We demonstrate experimentally that signal copying allows strong responses even without previous exposure and suggest that such hybrid calls may be especially favoured when pairwise interactions between species are strong.

Keywords
anti-predator behaviour, communication, interspecific interactions, learning, passerine birds
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-198595 (URN)10.1098/rspb.2012.3070 (DOI)000315953700014 ()
Available from: 2013-04-23 Created: 2013-04-22 Last updated: 2017-12-06Bibliographically approved
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