Publications
154 results found
Tobias JA, Sheard C, Seddon N, et al., 2016, Territoriality, social bonds, and the evolution of communal signaling in birds, Frontiers in Ecology and Evolution, Vol: 4, ISSN: 2296-701X
Communal signaling—wherein males and females collaborate to produce joint visual or acoustic displays—is perhaps the most complex and least understood form of communication in social animals. Although many communal signals appear to mediate competitive interactions within and between coalitions of individuals, previous studies have highlighted a confusing array of social and environmental factors that may explain the evolution of these displays, and we still lack the global synthesis needed to understand why communal signals are distributed so unevenly across large taxonomic and geographic scales. Here, we use Bayesian phylogenetic models to test whether acoustic communal signals (duets and choruses) are explained by a range of life-history and environmental variables across 10328 bird species worldwide. We estimate that duets and choruses occur in 1830 (18%) species in our sample and are thus considerably more widespread than previously thought. We then show that global patterns in duetting and chorusing, including evolutionary transitions between communal signaling and solo signaling, are not explained by latitude, migration, climate, or habitat, and only weakly correlated with cooperative breeding. Instead, they are most strongly associated with year-round territoriality, typically in conjunction with stable social bonds. Our results suggest that the evolution of communal signals is associated with the coordinated defense of ecological resources by stable coalitions of males and females, and that other widely reported associations are largely by-products of this underlying trend.
Cooney CR, Seddon N, Tobias JA, 2016, Widespread correlations between climatic niche evolution and species diversification in birds, Journal of Animal Ecology, Vol: 85, Pages: 869-878, ISSN: 1365-2656
1.The adaptability of species' climatic niches can influence the dynamics of colonisation and gene flow across climatic gradients, potentially increasing the likelihood of speciation, or reducing extinction in the face of environmental change. However, previous comparative studies have tested these ideas using geographically, taxonomically and ecologically restricted samples, yielding mixed results, and thus the processes linking climatic niche evolution with diversification remain poorly understood. 2.Focusing on birds, the largest and most widespread class of terrestrial vertebrates, we test whether variation in species diversification among clades is correlated with rates of climatic niche evolution, and the extent to which these patterns are modified by underlying gradients in biogeography and species' ecology. 3.We quantified climatic niches, latitudinal distribution and ecological traits for 7657 (~75%) bird species based on geographical range polygons, and then used Bayesian phylogenetic analyses to test whether niche evolution was related to species richness and rates of diversification across genus and family-level clades. 4.We found that the rate of climatic niche evolution has a positive linear relationship with both species richness and diversification rate at two different taxonomic levels (genus and family). Furthermore, this positive association between labile climatic niches and diversification was detected regardless of variation in clade latitude or key ecological traits. 5.Our findings suggest either that rapid adaptation to unoccupied areas of climatic niche space promotes avian diversification, or that diversification promotes adaptation. Either way, we propose that climatic niche evolution is a fundamental process regulating the link between climate and biodiversity at global scales, irrespective of the geographical and ecological context of speciation and extinction. This article is protected by copyright. All rights reserved.
Pigot AL, Tobias JA, Jetz W, 2016, Energetic Constraints on Species Coexistence in Birds, PLoS Biology, Vol: 14, ISSN: 1544-9173
The association between species richness and ecosystem energy availability is one of the major geographic trends in biodiversity. It is often explained in terms of energetic constraints, such that coexistence among competing species is limited in low productivity environments. However, it has proven challenging to reject alternative views, including the null hypothesis that species richness has simply had more time to accumulate in productive regions, and thus the role of energetic constraints in limiting coexistence remains largely unknown. We use the phylogenetic relationships and geographic ranges of sister species (pairs of lineages who are each other’s closest extant relatives) to examine the association between energy availability and coexistence across an entire vertebrate class (Aves). We show that the incidence of coexistence among sister species increases with overall species richness and is elevated in more productive ecosystems, even when accounting for differences in the evolutionary time available for coexistence to occur. Our results indicate that energy availability promotes species coexistence in closely related lineages, providing a key step toward a more mechanistic understanding of the productivity–richness relationship underlying global gradients in biodiversity.
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- Citations: 39
Collar NJ, Fishpool LDC, del Hoyo J, et al., 2016, Toward a scoring system for species delimitation: a response to Remsen, Journal of Field Ornithology, Vol: 87, Pages: 104-115, ISSN: 1557-9263
Pigot AL, Trisos CH, Tobias JA, 2016, Functional traits reveal the expansion and packing of ecological niche space underlying an elevational diversity gradient in passerine birds, PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 283, ISSN: 0962-8452
Bregman TP, Lees AC, Seddon N, et al., 2015, Species interactions regulate the collapse of biodiversity and ecosystem function in tropical forest fragments, Ecology, Vol: 96, Pages: 2692-2704, ISSN: 1939-9170
Competitive interactions among species with similar ecological niches are known to regulate the assembly of biological communities. However, it is not clear whether such forms of competition can predict the collapse of communities and associated shifts in ecosystem function in the face of environmental change. Here, we use phylogenetic and functional trait data to test whether communities of two ecologically important guilds of tropical birds (frugivores and insectivores) are structured by species interactions in a fragmented Amazonian forest landscape. In both guilds, we found that forest patch size, quality, and degree of isolation influence the phylogenetic and functional trait structure of communities, with small, degraded, or isolated forest patches having an increased signature of competition (i.e., phylogenetic and functional trait overdispersion in relation to null models). These results suggest that local extinctions in the context of fragmentation are nonrandom, with a consistent bias toward more densely occupied regions of niche space. We conclude that the loss of biodiversity in fragmented landscapes is mediated by niche-based competitive interactions among species, with potentially far-reaching implications for key ecosystem processes, including seed dispersal and plant damage by phytophagous insects.
Tobias JA, 2015, BIODIVERSITY Hidden impacts of logging, NATURE, Vol: 523, Pages: 163-164, ISSN: 0028-0836
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- Citations: 7
Matthews TJ, Sheard C, -Jones HEWC, et al., 2015, Ecological traits reveal functional nestedness of bird communities in habitat islands: a global survey, OIKOS, Vol: 124, Pages: 817-826, ISSN: 0030-1299
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- Citations: 23
Bath E, Wigby S, Vincent C, et al., 2015, Condition, not eyespan, predicts contest outcome in female stalk-eyed flies, Teleopsis dalmanni, Ecology and Evolution, Vol: 5, Pages: 1826-1836, ISSN: 2045-7758
In contests among males, body condition is often the key determinant of a successful outcome, with fighting ability signaled by so-called armaments, that is, exaggerated, condition-dependent traits. However, it is not known whether condition and exaggerated traits function in the same way in females. Here, we manipulated adult condition by varying larval nutrition in the stalk-eyed fly, Teleopsis dalmanni, a species in which eyespan is exaggerated in both sexes, and we measured the outcome of contests between females of similar or different body condition and relative eyespan. We found that females in higher condition, with both larger bodies and eyespan, won a higher proportion of encounters when competing against rivals of lower condition. However, when females were of equal condition, neither eyespan nor body length had an effect on the outcome of a contest. An analysis of previously published data revealed a similar pattern in males: individuals with large relative eyespan did not win significantly more encounters when competing with individuals of a similar body size. Contrary to expectations, and to previous findings in males, there was no clear effect of differences in body size or eyespan affecting contest duration in females. Taken together, our findings suggest that although eyespan can provide an honest indicator of condition, large eyespans provide no additional benefit to either sex in intrasexual aggressive encounters; body size is instead the most important factor.
Pigot AL, Tobias JA, 2015, Dispersal and the transition to sympatry in vertebrates, PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 282, ISSN: 0962-8452
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- Citations: 45
Trisos CH, Petchey OL, Tobias JA, 2014, Unraveling the Interplay of Community Assembly Processes Acting on Multiple Niche Axes across Spatial Scales, AMERICAN NATURALIST, Vol: 184, Pages: 593-608, ISSN: 0003-0147
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- Citations: 65
Edwards DP, Tobias JA, Sheil D, et al., 2014, Maintaining ecosystem function and services in logged tropical forests, TRENDS IN ECOLOGY & EVOLUTION, Vol: 29, Pages: 511-520, ISSN: 0169-5347
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- Citations: 258
Touchton JM, Seddon N, Tobias JA, 2014, Captive Rearing Experiments Confirm Song Development without Learning in a Tracheophone Suboscine Bird, PLOS One, Vol: 9, ISSN: 1932-6203
The origin of vocal learning in animals has long been the subject of debate, but progress has been limited by uncertainty regarding the distribution of learning mechanisms across the tree of life, even for model systems such as birdsong. In particular, the importance of learning is well known in oscine songbirds, but disputed in suboscines. Members of this diverse group (∼1150 species) are generally assumed not to learn their songs, but empirical evidence is scarce, with previous studies restricted to the bronchophone (non-tracheophone) clade. Here, we conduct the first experimental study of song development in a tracheophone suboscine bird by rearing spotted antbird (Hylophylax naevioides) chicks in soundproofed aviaries. Individuals were raised either in silence with no tutor or exposed to standardized playback of a heterospecific tutor. All individuals surviving to maturity took a minimum of 79 days to produce a crystallized version of adult song, which in all cases was indistinguishable from wild song types of their own species. These first insights into song development in tracheophone suboscines suggest that adult songs are innate rather than learnt. Given that empirical evidence for song learning in suboscines is restricted to polygamous and lek-mating species, whereas tracheophone suboscines are mainly monogamous with long-term social bonds, our results are consistent with the view that sexual selection promotes song learning in birds.
Fayet AL, Tobias JA, Hintzen RE, et al., 2014, Immigration and dispersal are key determinants of cultural diversity in a songbird population, BEHAVIORAL ECOLOGY, Vol: 25, Pages: 744-753, ISSN: 1045-2249
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- Citations: 26
Tobias JA, Cornwallis CK, Derryberry EP, et al., 2014, Species coexistence and the dynamics of phenotypic evolution in adaptive radiation, Nature, Vol: 506, Pages: 359-363, ISSN: 0028-0836
Interactions between species can promote evolutionary divergence of ecological traits and social signals1,2, a process widely assumed to generate species differences in adaptive radiation3,4,5. However, an alternative view is that lineages typically interact when relatively old6, by which time selection for divergence is weak7,8 and potentially exceeded by convergent selection acting on traits mediating interspecific competition9. Few studies have tested these contrasting predictions across large radiations, or by controlling for evolutionary time. Thus the role of species interactions in driving broad-scale patterns of trait divergence is unclear10. Here we use phylogenetic estimates of divergence times to show that increased trait differences among coexisting lineages of ovenbirds (Furnariidae) are explained by their greater evolutionary age in relation to non-interacting lineages, and that—when these temporal biases are accounted for—the only significant effect of coexistence is convergence in a social signal (song). Our results conflict with the conventional view that coexistence promotes trait divergence among co-occurring organisms at macroevolutionary scales, and instead provide evidence that species interactions can drive phenotypic convergence across entire radiations, a pattern generally concealed by biases in age.
Tobias JA, Planque R, Cram DL, et al., 2014, Species interactions and the structure of complex communication networks, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 111, Pages: 1020-1025, ISSN: 0027-8424
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- Citations: 82
Bregman TP, Sekercioglu CH, Tobias JA, 2014, Global patterns and predictors of bird species responses to forest fragmentation: Implications for ecosystem function and conservation, BIOLOGICAL CONSERVATION, Vol: 169, Pages: 372-383, ISSN: 0006-3207
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- Citations: 229
Gonzalez J-CT, Sheldon BC, Tobias JA, 2013, Environmental stability and the evolution of cooperative breeding in hornbills, PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 280, ISSN: 0962-8452
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- Citations: 43
Gonzalez J-CT, Sheldon BC, Collar NJ, et al., 2013, A comprehensive molecular phylogeny for the hornbills (Aves: Bucerotidae) (vol 67, pg 468, 2013), MOLECULAR PHYLOGENETICS AND EVOLUTION, Vol: 68, Pages: 715-715, ISSN: 1055-7903
Seddon N, Botero CA, Tobias JA, et al., 2013, Sexual selection accelerates signal evolution during speciation in birds, Proceedings of the Royal Society B: Biological Sciences, Vol: 280, ISSN: 0962-8452
Sexual selection is proposed to be an important driver of diversification in animal systems, yet previous tests of this hypothesis have produced mixed results and the mechanisms involved remain unclear. Here, we use a novel phylogenetic approach to assess the influence of sexual selection on patterns of evolutionary change during 84 recent speciation events across 23 passerine bird families. We show that elevated levels of sexual selection are associated with more rapid phenotypic divergence between related lineages, and that this effect is restricted to male plumage traits proposed to function in mate choice and species recognition. Conversely, we found no evidence that sexual selection promoted divergence in female plumage traits, or in male traits related to foraging and locomotion. These results provide strong evidence that female choice and male-male competition are dominant mechanisms driving divergence during speciation in birds, potentially linking sexual selection to the accelerated evolution of pre-mating reproductive isolation.
Gonzalez J-CT, Sheldon BC, Collar NJ, et al., 2013, A comprehensive molecular phylogeny for the hornbills (Ayes: Bucerotidae), MOLECULAR PHYLOGENETICS AND EVOLUTION, Vol: 67, Pages: 468-483, ISSN: 1055-7903
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- Citations: 22
Pigot AL, Tobias JA, 2013, Species interactions constrain geographic range expansion over evolutionary time, ECOLOGY LETTERS, Vol: 16, Pages: 330-338, ISSN: 1461-023X
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- Citations: 177
Tobias JA, Şekercioǧlu CH, Vargas HF, 2013, Bird conservation in tropical ecosystems: challenges and opportunities, Key Topics in Conservation Biology 2, Pages: 258-276, ISBN: 9780470658765
Bird conservation is a global mission but most of the key battles are being played out in the tropics. This chapter summarizes the key attributes of tropical ecosystems and implications for bird conservation. First, it outlines threats to key tropical environments. Then it argues that tropical species often differ from their temperate-zone counterparts in ways that pose novel challenges for conservation. The chapter concludes that sustainable conservation of tropical birds and the ecosystem services they provide will be achieved only if attention is focused on biotic processes and interactions operating at larger spatial and temporal scales. The strategies proposed by the authors have broad relevance for the management of tropical diversity because birds have long been viewed as a model system for assessing conservation priorities, and act as flagships for numerous conservation programmes. © 2013 John Wiley & Sons, Ltd.
Derryberry EP, Seddon N, Claramunt S, et al., 2012, CORRELATED EVOLUTION OF BEAK MORPHOLOGY AND SONG IN THE NEOTROPICAL WOODCREEPER RADIATION, EVOLUTION, Vol: 66, Pages: 2784-2797, ISSN: 0014-3820
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- Citations: 82
Tobias JA, Montgomerie R, Lyon BE, 2012, The evolution of female ornaments and weaponry: social selection, sexual selection and ecological competition, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 367, Pages: 2274-2293, ISSN: 0962-8436
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- Citations: 328
Salisbury CL, Seddon N, Cooney CR, et al., 2012, The latitudinal gradient in dispersal constraints: ecological specialisation drives diversification in tropical birds, ECOLOGY LETTERS, Vol: 15, Pages: 847-855, ISSN: 1461-023X
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- Citations: 106
Tobias JA, Brawn JD, Brumfield RT, et al., 2012, The importance of suboscine birds as study systems in ecology and evolution, Ornitologia Neotropical, Vol: 23, Pages: 261-274, ISSN: 1075-4377
Suboscine passerine birds are one of the most prominent components of Neotropical avifaunas, yet they remain relatively poorly studied in comparison with their sister-clade, the oscine passerines. This situation appears to be changing rapidly as more ornithologists realize that suboscine birds offer ideal study systems for investigating a variety of research questions. We summarise a symposium focused on studies of tracheophone suboscines (woodcreepers, ovenbirds, antbirds and allies) and highlight recent advances in our understanding of their history and behavior. We argue that because of their antiquity and high levels of diversity, they make excellent subjects for comparative analyses and phylogenetic models. Moreover, several details of their breeding and signaling systems predispose them to field-based observational and experimental studies of social interactions and signal evolution, as well as automated techniques for vocal recognition. We discuss potential new avenues of research on suboscine passerines, and conclude that they are likely to play an increasingly important role as study systems in tropical ecology and evolutionary biology.
Safran RJ, Flaxman SM, Kopp M, et al., 2012, A robust new metric of phenotypic distance to estimate and compare multiple trait differences among populations, CURRENT ZOOLOGY, Vol: 58, Pages: 426-439, ISSN: 1674-5507
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- Citations: 24
Tobias JA, Gamarra-Toledo V, Garcia-Olaechea D, et al., 2011, Year-round resource defence and the evolution of male and female song in suboscine birds: social armaments are mutual ornaments, JOURNAL OF EVOLUTIONARY BIOLOGY, Vol: 24, Pages: 2118-2138, ISSN: 1010-061X
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- Citations: 82
Barlow J, Ewers RM, Anderson L, et al., 2011, Using learning networks to understand complex systems: a case study of biological, geophysical and social research in the Amazon, BIOLOGICAL REVIEWS, Vol: 86, Pages: 457-474, ISSN: 1464-7931
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- Citations: 39
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