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Wheatcroft, David
Publications (10 of 14) Show all publications
Suzuki, T. N., Wheatcroft, D. & Griesser, M. (2018). Call combinations in birds and the evolution of compositional syntax. PLoS biology, 16(8), Article ID e2006532.
Open this publication in new window or tab >>Call combinations in birds and the evolution of compositional syntax
2018 (English)In: PLoS biology, ISSN 1544-9173, E-ISSN 1545-7885, Vol. 16, no 8, article id e2006532Article in journal, Editorial material (Refereed) Published
Abstract [en]

Syntax is the set of rules for combining words into phrases, providing the basis for the generative power of linguistic expressions. In human language, the principle of compositionality governs how words are combined into a larger unit, the meaning of which depends on both the meanings of the words and the way in which they are combined. This linguistic capability, i.e., compositional syntax, has long been considered a trait unique to human language. Here, we review recent studies on call combinations in a passerine bird, the Japanese tit (Parus minor), that provide the first firm evidence for compositional syntax in a nonhuman animal. While it has been suggested that the findings of these studies fail to provide evidence for compositionality in Japanese tits, this criticism is based on misunderstanding of experimental design, misrepresentation of the importance of word order in human syntax, and necessitating linguistic capabilities beyond those given by the standard definition of compositionality. We argue that research on avian call combinations has provided the first steps in elucidating how compositional expressions could have emerged in animal communication systems.

Place, publisher, year, edition, pages
PUBLIC LIBRARY SCIENCE, 2018
National Category
Zoology General Language Studies and Linguistics
Identifiers
urn:nbn:se:uu:diva-364731 (URN)10.1371/journal.pbio.2006532 (DOI)000443383300035 ()30110321 (PubMedID)
Available from: 2018-11-01 Created: 2018-11-01 Last updated: 2018-11-01Bibliographically approved
Sirkiä, P. M., McFarlane, S. E., Jones, W., Wheatcroft, D., Ålund, M., Rybinski, J. & Qvarnström, A. (2018). Climate-driven build-up of temporal isolation within a recently formed avian hybrid zone.. Evolution, 72(2), 363-374
Open this publication in new window or tab >>Climate-driven build-up of temporal isolation within a recently formed avian hybrid zone.
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2018 (English)In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 72, no 2, p. 363-374Article in journal (Refereed) Published
Abstract [en]

Divergence in the onset of reproduction can act as an important source of reproductive isolation (i.e., allochronic isolation) between co-occurring young species, but evidence for the evolutionary processes leading to such divergence is often indirect. While advancing spring seasons strongly affect the onset of reproduction in many taxa, it remains largely unexplored whether contemporary spring advancement directly affects allochronic isolation between young species. We examined how increasing spring temperatures affected onset of reproduction and thereby hybridization between pied and collared flycatchers (Ficedula spp.) across habitat types in a young secondary contact zone. We found that both species have advanced their timing of breeding in 14 years. However, selection on pied flycatchers to breed earlier was weaker, resulting in a slower response to advancing springs compared to collared flycatchers and thereby build-up of allochronic isolation between the species. We argue that a preadaptation to a broader niche use (diet) of pied flycatchers explains the slower response to raising spring temperature, but that reduced risk to hybridize may contribute to further divergence in the onset of breeding in the future. Our results show that minor differences in the response to environmental change of co-occurring closely related species can quickly cause allochronic isolation.

Keywords
Competitive exclusion, ecological speciation, prezygotic isolation, reinforcement, speciation, temporal segregation
National Category
Evolutionary Biology Ecology
Identifiers
urn:nbn:se:uu:diva-341102 (URN)10.1111/evo.13404 (DOI)000424131100011 ()29214649 (PubMedID)
Funder
Swedish Research CouncilAcademy of Finland
Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2018-11-19Bibliographically approved
Wheatcroft, D. & Price, T. D. (2018). Collective Action Promoted by Key Individuals. American Naturalist, 192(4), 401-414
Open this publication in new window or tab >>Collective Action Promoted by Key Individuals
2018 (English)In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 192, no 4, p. 401-414Article in journal (Refereed) Published
Abstract [en]

Explaining why individuals participate in risky group behaviors has been a long-term challenge. We experimentally studied the formation of groups of birds (mobs) that aggressively confront predators and avian nest parasites and developed a theoretical model to evaluate the conditions under which mobs arise. We presented taxidermied mounts of predators on adult birds (hawks and owls) and of nest threats (crows and cuckoos) at different distances to nests of Phylloscopus warblers. Even when alone, birds are aggressive toward predators of adult birds, both at and away from their nests. By contrast, birds aggressively confront nest threats alone only when they have a nest nearby. However, strong initial responses by nest owners lead individuals without nearby nests to increase their responses, thereby generating a mob. Building on these findings, we derive the conditions in which individuals are incentivized to invest more when joining a high-gain individual compared to when acting alone. Strong responses of high-gain individuals acting alone tend to reduce the investments of other high-gain individuals that subsequently join. However, individuals that benefit sufficiently little from acting alone increase their investments when joining a high-gain individual and can even be sufficiently incentivized to join in when they would otherwise not act alone. Together, these results suggest an important role for key individuals in the generation of some group behaviors.

Place, publisher, year, edition, pages
UNIV CHICAGO PRESS, 2018
Keywords
antipredator behavior, by-product mutualism, collective action, cooperation, group formation, mobbing behavior
National Category
Zoology
Identifiers
urn:nbn:se:uu:diva-365285 (URN)10.1086/698874 (DOI)000444262900003 ()30205027 (PubMedID)
Available from: 2018-11-13 Created: 2018-11-13 Last updated: 2018-11-13Bibliographically approved
Griesser, M., Wheatcroft, D. & Suzuki, T. N. (2018). From bird calls to human language: exploring the evolutionary drivers of compositional syntax. CURRENT OPINION IN BEHAVIORAL SCIENCES, 21, 6-12
Open this publication in new window or tab >>From bird calls to human language: exploring the evolutionary drivers of compositional syntax
2018 (English)In: CURRENT OPINION IN BEHAVIORAL SCIENCES, ISSN 2352-1546, Vol. 21, p. 6-12Article, review/survey (Refereed) Published
Abstract [en]

Compositional syntax, where lexical items are combined into larger units, has been assumed to be unique to human language. Recent experiments, however, showed that Japanese tits combine alert and recruitment calls into alert-recruitment sequences when attracting conspecifics to join in mobbing a predator. We speculate that such call combinations are favoured when: Firstly, callers and receivers have shared interests in exchanging information; secondly, species produce different types of calls in different situations, leading to distinct behavioural responses in receivers; and finally, complex situations exist in which receivers benefit by combining two or more behaviours. These preconditions were also present in human ancestors. Thus, future work on bird calls may provide insights into the evolution of compositional syntax in human language.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Zoology
Identifiers
urn:nbn:se:uu:diva-366316 (URN)10.1016/j.cobeha.2017.11.002 (DOI)000440543600003 ()
Funder
EU, Horizon 2020, 665778
Available from: 2018-11-20 Created: 2018-11-20 Last updated: 2018-11-20Bibliographically approved
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
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