ORNITOLOGIA NEOTROPICAL 23: 259–272, 2012 © The Neotropical Ornithological Society

THE IMPORTANCE OF NEOTROPICAL SUBOSCINE AS STUDY SYSTEMS IN ECOLOGY AND EVOLUTION

J. A. Tobias 1, J. D. Brawn 2, R. T. Brumfield3 , E. P. Derryberry 3, A. N. G. Kirschel 1,4, N. Seddon 1

1Edward Grey Institute, Department of Zoology, University of Oxford, UK 2Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, Illinois 61801 USA 3Museum of Natural Science and Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803 4Department of Biological Sciences, University of Cyprus, PO Box 20537, Nicosia 1678, Cyprus

Abstract. – Suboscine 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 . 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, , 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 experimen- tal 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.

Suboscine birds account for over 10% (;1150 this larger total is made up of general studies, species) of global diversity, and around a which potentially include at least some data fifth of passerine diversity. They have radiated from suboscines, but the vast majority is to a spectacular extent in the Neotropics, focused specifically on oscines. Indeed, the which is home to all but a handful of true research output based on oscine systems suboscine species (Ricklefs 2002). Despite this, is far higher than these calculations imply as they have received remarkably little research much of it is published without noting the attention in comparison with their sister- word “passerine”, including many thousands clade, the oscine passerines, which abound in of papers on high-profile model systems the temperate zone. A preliminary survey of such as great tits (Parus major), red-winged literature reveals that 202 articles published blackbirds (Agelaius phoenicius) and zebra since 1926 contain “suboscine” in the title finches Taeniopygia( guttata). or abstract (see Fig. 1). This may appear Further research biases exist within substantial, but it contrasts markedly with the the subsocines. The infraorder Tyrannides, 17,852 papers published in the same period sometimes referred to as the non-tracheo- containing the word “passerine” and excluding phone (or “bronchophone”) suboscines, a the word “suboscine”. A small proportion of clade primarily consisting of tyrant-flycatchers

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FIG. 1. Increasing rate of publication for papers focused on suboscines, since 1926 (data binned into 5-year periods). Totals are numbers of papers containing the word “suboscine” in title, abstract or keywords ex- tracted from Web of Knowledge. We do not make a direct comparison with oscines because most papers focusing on suboscines tend to highlight the fact, whereas those focusing on oscines do not.

(Tyrannidae), (Pipridae) and The situation has changed rapidly (Cotingidae), has received the most attention. over recent years as a growing number of Conversely, the infraorder Furnariides, i.e. researchers have realized that tracheophone tracheophone families such as the antbirds suboscines make ideal research subjects for (Thamnophilidae) and ovenbirds (Furnariidae), a number of practical reasons. First, they are has traditionally been largely ignored. The ecologically diverse, occurring in all major historical emphasis on Tyrannides has occurred habitats from humid lowland tropical forests to in part because several lineages colonized the the snowline. Second, they are socially diverse, temperate zone, breeding as far north as the spanning a variety of breeding systems from United States and Canada. Moreover, tropical social monogamy to cooperative breeding. forms such as manakins and cotingas are Third, they are typically highly responsive to often highly charismatic, with extreme sexual tape playback, making them relatively easy to dimorphism and extravagantly ornamented catch in mistnets, and therefore to measure, males. In contrast, tracheophone suboscines color-band, radio-tag, blood-sample and so are absent from the temperate zone, and tend on (Bard et al. 2002). It also means that they to be overlooked even in the tropics because are amenable to playback experiments. Fourth, they are perceived as dull or difficult to study many species of suboscines are fairly common, (Remsen 2003). loud and conspicuous, even in human-modified

260 THE IMPORTANCE OF NEOTROPICAL SUBOSCINE BIRDS AS STUDY SYSTEMS IN ECOLOGY AND EVOLUTION environments. This means that it is relatively suboscine clades are amenable to comparative easy to find and follow them for the purpose analyses based on simple visual comparison of observational studies, and to record their of plumage colours and contrasts, rather than vocalizations. Thus, it is possible to build up the use of colour spectrophotometry coupled sufficient sample sizes (in terms of numbers with visual modelling (e.g. Seddon et al. 2008). of individuals) for statistical tests an important Another aspect that has drawn researchers consideration given that many tropical species to the tracheophone suboscines is the are found at lower population densities than contrasting perspective they provide on a their temperate-zone counterparts (Tobias et number of long-standing questions (Ricklefs al. 2012b). 2002). In particular, they offer unparalleled The signaling systems of tracheophone systems for studying the evolutionary suboscines also offer intrinsic practical implications of ‘slow’ life history strategies. advantages for biologists. For example, it is well Most members of this clade are characterized known that their vocalizations are relatively by classic tropical social systems involving simple and stereotyped (Kroodsma 1984, convergent sex-roles, long-term pair-bonds Morton 1996, Lindell 1998), thus facilitating and year-round territoriality (Greenberg and acoustic analyses used in tests of evolutionary Gradwohl 1983, Kirschel et al. 2011, Tobias et theory (e.g. Seddon 2005) and speciation (e.g. al. 2011). As a corollary, they also tend to be Seddon and Tobias 2007, Seddon et al. 2008), extremely sedentary (Greenberg & Gradwohl as well as analyses of geographic variation 1997, Woltmann et al. 2012), with delayed natal (Ippi et al. 2011) and criteria for assessing dispersal and highly stable territorial networks species limits (Isler et al. 1998, Tobias et al. (Greenberg & Gradwohl 1986, Kirschel et 2010a). This contrasts with many oscine taxa al. 2011). Overt evidence of sexual selection in which song learning is prominent, leading such as polygyny and extra-pair fertilizations to complex local and regional variation in appears to be rare (Fleischer et al. 1997), vocalizations (e.g. individual repertoires, although divorce and territory switching may dialects), such that mechanisms of ecological exert more cryptic forms of sexual selection or social selection are difficult to disentangle (Morton et al. 2000, Tobias et al. 2009a). from cultural evolution (Tobias et al. 2010b). These features contrast with many avian Similarly, the finding that many oscine model systems, which tend to have short-term groups have high levels of plumage reflectance pair-bonds, seasonal territoriality and high- in ultra-violet (UV) wavelengths, as well as levels of overt sexual selection, particularly visual sensitivity to such wavelengths, suggests in the temperate zone. Even tropical studies that the use of human vision to assess plumage often focus on visually attractive species with colors and contrasts is invalid (Eaton 2005). extreme sexual dichromatism and male-biased Human vision is insensitive to UV wavelengths ornamentation, such as manakins (Pipridae). and thus numerous previous studies have Thus, tracheophone suboscines offer useful overlooked cases of signal divergence or insight into overlooked questions about cryptic dichromatism in oscine birds (Bleiweiss the origins and implications of long-term 2004, Eaton 2006). These problems are monogamous partnerships and selection on negligible in tracheophone suboscines as their females (Tobias et al. 2012a). Much of the plumage generally has very low levels of UV work to date has focused on the evolution of reflectance and the spectral sensitivity of their communal displays, such as duets, and their visual systems is not tuned to UV wavelengths multiple functions in cooperative resource (Seddon et al. 2009). This means that defense, mate defense (Seddon and Tobias

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2006) and sexual conflict between partners 1979 and continues today, along with a series (Tobias and Seddon 2009c). of single species or comparative studies often Two final reasons why tracheophone involving species from tropical and north suboscines are becoming increasingly popular temperate latitudes. Suboscine passerines are in studies of evolution and ecology are their prominent in the sample, e.g. 25 (71%) of 35 enigmatic evolutionary history and sheer species for which data are sufficient to estimate diversity. Because their plumage is relatively demographic parameters. Others studies subdued, they have proved to be a hotbed for conducted in neotropical forests report similar the discovery or description of cryptic species proportions of subocines when sampling (e.g. Zimmer 1997, Isler et al. 2007, 2009, Chaves understory species with mist nets (see Karr et et al. 2010) and genera (Chesser et al. 2009, al 1990). Claramunt et al., 2010, Derryberry et al., 2010a, A series of analyses comparing tropical and 2010b). Moreover, the challenge of numerous north temperate species indicates a complex unresolved evolutionary relationships has suite of associations among key traits such attracted the attention of molecular biologists, as survival rate, body mass, stress responses, such that extensive phylogenetic trees are now reproductive effort, energetics, and immune available (e.g. Irestedt et al. 2002, Chesser 2004, function (see summary in Robinson et al. Moyle et al. 2009, Derryberry et al. 2011). 2010). The "fast-slow" axis summarizing the This combination of high species richness pace of life histories is a useful metaphor for and availability of phylogenetic data has made comparative studies, but tropical and temperate the tracheophone suboscines an increasingly species do not necessarily ordinate "cleanly" on important system for multi-species studies this gradient. Comparison of species sampled testing evolutionary and ecological theory, and in North America and Panama indicate that for models of diversification in particular (e.g. certain traits such as energy expenditure (e.g., Ricklefs 2006, Seddon et al. 2008, Claramunt field metabolic rate), and constitutive immune 2010, Gómez et al. 2010, Claramunt et al. function (i.e., the part of immune system that 2011). is not induced by the presence of a pathogen), These factors help to explain why the tropical species do seem to have a slow pace output of research focused on suboscines has of life whereby investment is structured increased exponentially in recent years (Fig. 1). by a comparatively long expected lifespan. The goal of this symposium was to summarise Alternatively, parental effort and survival rate advances in our understanding of suboscine do not exhibit an obvious tradeoff. The classic birds, to emphasise the insights they provide view of avian life histories at tropical latitudes on life-history evolution, signal evolution and is that they live longer and therefore invest less speciation, and to clarify the main avenues for in any one reproductive cycle. future research. The characteristically small clutch size of tropical species is typically invoked as evidence What do suboscines tell us of this tradeoff. Yet, a series of recent studies about avian life histories? conducted on the Western Slaty Antshrike (Thamnophilus atrinucha) reports significant Jeff Brawn summarized some of findings of investment with respect post-fledging long-term population studies of understory parental care (Tarwater and Brawn 2010). species in the lowland forests of central Tropical species my therefore have a “quality Panama. These studies include capture-mark- over quantity” strategy that is somewhat release (CMR) sampling that was initiated in independent of expected longevity.

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Overall, these studies reveal little “signal” or song types, of another species (Helb et al. constraint owing to phylogenetic history (e.g., K. 1985). Again, the convergent songs produced Lee unpublished MS). Nonetheless, Cohen et by this form of copying lack a genetic basis, al. (2008) report that correlations among traits and therefore do not qualify as character (e.g., between concentrations of circulating displacement driven by divergent selection antioxidants survival rate), and therefore potential (Tobias & Seddon 2009b). tradeoffs, can vary between suites of oscine Because of these issues, the nature of and suboscines. It may be that certain traits are song development in suboscine birds takes somewhat constrained by history while others on greater importance. Suboscine songs are vary more “freely” within a clade. Clearly, much often proposed to develop without learning of what we know about the demography and life (Kroodsma 1984, Isler et al. 1998, Zimmer histories of tropical species comes from studies & Isler 2003), potentially offering a useful of suboscines. The message emerging from contrasting system for studies of signal these studies is that the life histories of tropical evolution. However, this paradigm has been species are not easily categorized and that further challenged over recent years, suggesting studies are required in diverse ecological settings that further work is required to validate within the Neotropics. assumptions. To address this question, spotted antbirds (Hylophylax naevioides) were reared by Development, function hand from the egg in soundproofed aviaries at and evolution of song in the Smithsonian Tropical Research Institute in Neotropical suboscines Panama. Developing chicks were raised either in silence or were exclusively exposed to the song Nathalie Seddon discussed the implications of a related species with a distinctly different of song learning, or lack thereof, for studies song (Hylophylax naevius). All of the five of evolution. Oscine song has been used to individuals that survived to maturity produced test numerous evolutionary ideas, but the normal adult song, which is consistent with fact that in many species these songs develop the hypothesis that tracheophone suboscines through an imprinting-like process means that develop songs without learning. conclusions may not be valid. For example, it is In the light of these findings it is useful to often argued that habitat-related differences in weigh up the evidence that song learning may oscine song are the result of acoustic adaptation be widespread in suboscines. Looking broadly (e.g. Nicholls et al. 2006, Derryberry 2009) but across all suboscine species, rudimentary it could just as easily be explained by young song learning has been suspected in only individuals learning the songs, or parts of three species, all of which have lekking or songs, that they perceive most clearly in their polygamous reproductive strategies. Trainer natal habitat (Hansen 1979). For this reason, et al. (2001) proposed that male Chiroxiphia habitat-associated patterns of oscine song linearis adjust song frequency by copying lek- variation may lack a genetic basis, reflecting mates, yet Trainer & Parsons (2002) found no phenotypic plasticity rather than acoustic microgeographic variation in song structure, adaptation (Ripmeester et al. 2010). Similarly, suggesting that learning is minor or absent. oscine song convergence in contact zones Similarly, lek-specificity of songs in Lipaugus has been attributed to convergent character vociferans may indicate learning (Fitzsimmons et displacement (Cody 1969) but it could simply al. 2008), but the evidence is weak (Kroodsma be explained by heterospecific copying, where 2011). Finally, the finding that geographic one species accidentally learns the song, or variation in male songs of Procnias tricarunculata

263 Tobias et al. was not explained by genetic variation is again sound transmission properties of Amazonian suggestive of learning (Saranathan et al. 2007), habitats, and therefore subject to diversifying as this tends to produce a mismatch between selection in heterogeneous environments vocal and genetic variation (Nicholls et al. (Tobias et al. 2010). It also helps to explain 2006). However, the subtle mismatch detected high levels of stereotypy and individual in Procnias tricarunculata could potentially be distinctiveness, features which have been explained by phenotypic plasticity unrelated to shown to facilitate individual (mate) and species learning. Thus, the evidence for song learning in recognition in antbirds, even when overall suboscines remains weak, and entirely restricted differences in signal design are very small to lineages with lek-breeding reproductive (Seddon and Tobias 2010). These findings fit strategies (i.e. strong sexual selection). with the results of other mate removal and Balanced against these largely inconclusive playback experiments in Amazonia confirming cases, we note that experimental studies in that male and female songs in antbirds have socially monogamous non-tracheophones dual functions in mate attraction and territory found no evidence of learning (Kroodsma defense (Tobias et al. 2011). Taken together, 1984), nor the forebrain cell clusters that these findings suggest that song divergence, control song acquisition in oscines (Kroodsma mediated by ecological adaptation and and Konishi 1981). Switching attention to social selection, could play a key role in the tracheophone suboscines, several studies diversification of suboscine birds. suggest that their songs are innate: (1) individual variation in song structure is low, Using song recordings and with no indication of mimicry, repertoires and playback experiments to map dialects (Lindell 1998; Bard et al. 2002; Seddon territories and infer song and Tobias 2006); (2) geographical variation in function songs and genes is typically concordant (Isler et al. 2005; Chavez et al. 2010); (3) in one species The simplicity and stereotypy of suboscine songs (Thamnophilus doliatus), captive individuals suggests that they are amenable to automated produced normal songs as adults after being song feature extraction procedures used to reared in silence or exposed to heterospecific identify songs to species (Trifa et al. 2008), or tutors during the nestling phase (Kroodsma even individuals (Bard et al. 2002, Kirschel et 1984); (4) unlike hybrid oscines in which songs al. 2009, 2011), with potential applications to are typically copied from the parental male, improving our understanding of the ecology hybrid tracheophone suboscines produce of poorly known species. Early attempts structurally intermediate songs (Cadena et al. to apply automated algorithms to the vocal 2007). We also note that there are no cases of identification of 5 species occurring in lekking or polygamous reproductive strategies a Mexican rainforest worked reasonably well, in this clade (Marantz et al. 2003; Remsen with 98% successful classification achieved 2003; Zimmer and Isler 2003). These facts, in (Trifa et al. 2008). Alex Kirschel presented work conjunction with the evidence from captive- exploring this further at the individual level in rearing experiments, are consistent with the the Mexican antthrush (Formicarius moniliger), idea that song learning is minimal, or even a monomorphic species where female song nonexistent, in all tracheophone suboscines. appears indistinguishable from male song. Minimal learning in suboscines adds Like many Ground Antbirds (), weight to recent studies showing that acoustic Mexican antthrush are very difficult to see in structure of suboscine songs is predicted by the field, so identifying individuals or their

264 THE IMPORTANCE OF NEOTROPICAL SUBOSCINE BIRDS AS STUDY SYSTEMS IN ECOLOGY AND EVOLUTION sex is very challenging. Using song recordings of signals, such as limits on movements of and statistical classifications, however, it was the vocal tract during song production in birds possible to identify over 30 individuals in a 50 (Nowicki et al. 1992). Signals may therefore hectare study area in Chiapas, Mexico, and to diverge as a by-product of morphological map territory occupancy over a 5-year period. adaptation to different foraging niches and Songs were found to be largely invariant from habitats (Podos and Hendry, 2006). Such year to year and individuals’ songs could thus morphological traits have been referred to as be recognized with accuracies over 80% ‘magic traits’ (Gavrielts 2004) when they affect among different years. Territory locations the production of mating signals because were determined by mapping where identified divergent ecological selection can give rise birds were recorded singing, including where indirectly to non-random mating. possible, with the use of a wireless sensor Much of the evidence for an indirect effect network (Collier et al. 2010, Kirschel et al. of ecological selection on signals comes from 2011). Based on the distribution of songs it was studies of oscine song (Badyaev et al. 2008, possible to determine that shapes and sizes of Ballentine, 2006; Huber and Podos, 2006; Podos, territories can vary over time when individuals 2001). The link between ecological selection are replaced from their territories, and territory and signal evolution is particularly clear in birds dynamics varied between males and females (Podos, 2001), as the organ used to forage the (Kirschel et al. 2011). Moreover, by identifying beak can also be used to modulate the resonance the song of each individual, it was possible to properties of the vocal tract during sound determine when males and females sang. The production (Westneat et al. 1993). For example, song similarity between the sexes – a method to beak size and shape in Darwin's finches is distinguish song to sex has still not been found often forwarded as one of the best examples – suggests convergence between the sexes in of a 'magic trait' linking ecological divergence territory defense. Intrasexual territory defense to reproductive isolation (Pfennig and Pfennig, appears commonplace in suboscines (Seddon 2010; Servedio et al. 2011). Because most work and Tobias 2006, Tobias et al. 2011), but song on the indirect effects of ecological selection convergence among the sexes might facilitate have been conducted on oscines, it is difficult intersexual competition in ground antbirds. to tease apart the influence of cultural processes on vocal evolution from the potential impact of Morphological adaptation morphological and ecological adaptation (Seddon, shapes vocal evolution in 2005), and suggests that the conclusions of a morphologically diverse previous studies may only apply to song-learning radiation of suboscine birds birds (; 40% of all avian species). A few studies outside of oscines (Anatidae: Hausberger et al. Divergence of signals used in mate choice 1991; Furnariidae: Palacios and Tubaro, 2000; and male-male competition can promote the Thamnophilidae: Seddon, 2009) suggest that the process of speciation (Coyne and Orr, 2004). mechanistic link between beaks and songs may Thus, understanding the evolutionary forces be more widespread but its generality remains that shape signal divergence is fundamental to unclear. Here, we explore the interface between our understanding of phenotypic evolution and morphological and vocal evolution in a major diversification. One important route of signal radiation of suboscine birds, the woodcreepers divergence is via ecological selection on traits (Dendrocolaptinae). Unlike oscine passerines related to signal production. There are often (the focus of previous studies), suboscines make biomechanical limitations on the production ideal subjects because they develop their songs

265 Tobias et al. with minimal learning, and hence patterns of tend to produce high performance songs. vocal divergence are not complicated by cultural The evolution of performance is associated evolution. closely with the evolution of beak size over Using a well-resolved molecular phylogeny time. Altogether, our findings suggest that of the woodcreepers (Derryberry et al., limitations on signal production may play 2011), we tested the vocal tract constraint an important role not only in the evolution hypothesis (Podos, 1997). This taxonomically of oscine songs but also in the evolution of widespread constraint is a tradeoff between vocal signals in woodcreepers. Our results the rate at which sounds are produced and add weight to previous studies proposing a the frequency bandwidth of those sounds, as link between beak size and song structure described in more than 40 species of oscines in suboscines (Palacios and Tubaro, 2000, (Passeri; reviewed in Podos et al., 2009) Seddon, 2005), suggesting that correlated including a large number of wood warblers evolution via biomechanical constraints may (Parulidae: Cardoso and Hu, 2011) and one be widespread in birds. species of seabird (Stercorariidae: Janicke et Because divergence in woodcreeper vocal al. 2008). If this constraint is an important signals is in part a by-product of ecological factor in song diversification and evolution in selection on beak morphology, our results suboscines, then woodcreeper songs should have important implications for the role occupy a bounded acoustic space of frequency of ecology in suboscine diversification We bandwidth as a function of the rate of note hypothesize that strong ecological selection production. We also tested the hypothesis that during the adaptation of woodcreepers there is a biomechanical limit on performance to different habitats and foraging niches of this motor constraint related to beak size promotes divergence in beak morphology (Podos, 2001). This hypothesis has been among species, and that this leads, indirectly, examined most intensively in Darwin’s finches to acoustic divergence in songs. Because (Herrel, et al. 2008; Huber and Podos, 2006; vocalizations mediate species recognition in Podos, 2001). As found in Darwin's finches, this clade, our results are also consistent with we predicted a negative relationship between the idea that beak morphology serves as a beak size and ability to perform the trade-off ‘magic trait’ not only in some oscine clades but between frequency bandwidth and pace. across the entire passerine radiation (>5000 Our results suggest that the proximate species), and that ‘magic traits’ themselves are features of signal production influence the relatively widespread (Servedio et al. 2011). evolution and diversification of woodcreeper Nonetheless, we still have much to learn about songs (Derryberry et al. 2012). We found the extent to which ecological selection on evidence that woodcreeper songs have beak morphology has had a pleiotropic effect diversified within a bounded acoustic space on the diversification of song, and the extent such that slow songs are produced at a to which song divergence in turn influences range of frequency bandwidths but as song reproductive isolation in suboscine clades. pace increases, maximal values of frequency bandwidth decrease. We also found a positive The role of species relationship between beak size and ability to interactions in phenotypic perform the trade-off between frequency evolution bandwidth and pace: species with large beaks tend to produce low performance Classical evolutionary theory predicts that songs, whereas species with small beaks phenotypes of closely related species diverge

266 THE IMPORTANCE OF NEOTROPICAL SUBOSCINE BIRDS AS STUDY SYSTEMS IN ECOLOGY AND EVOLUTION in sympatry by character displacement, divergent character displacement may apply i.e. selection acting to minimize costs of to the recognition mechanism rather than to ecological and reproductive interference the acoustic trait itself. (Grant 1972, Losos 2000, Pfennig & Pfennig 2009). However, direct evidence Future steps of divergent character displacement is Genetics underlying song design largely restricted to young taxa, and much Fleshing out the genetic sampling required remains to be learnt about how species at the species level, particularly across tyrant- interactions shape phenotypic evolution flycatchers etc over the longer timeframes of evolutionary True impression of biological diversity which radiations. Joe Tobias reported an extensive seems to be greatly underestimated comparative analysis designed to explore Further exploration of use of song in this question, using Neotropical ovenbirds automated identification of species and as model systems. Data on ecological traits individuals. (beak shape and tarsus length) and signaling traits (song structure) were collected from Studies should be very cautious pooling specimens and field recordings of 350 samples of oscine and suboscine species lineages (including intraspecific lineages). together. The results showed that occurrence in sympatry did not predict trait divergence, These factors make many suboscines ideal for contrary to the predictions of character field studies of behavior and life history, and displacement theory. The only significant for testing broader hypotheses about the role pattern detected was greater similarity of of social and ecological selection on evolution songs in sympatric lineages versus allopatric and diversification. lineages. This apparent convergence in songs can either be attributed to acoustic adaptation Acknowledgements to shared environments, or to convergent character displacement driven by interspecific We thank the NOC scientific program territoriality (Cody 1969). It was noted that committee for their efforts in organizing an several old furnariid lineages with interspecific excellent meeting. We also thank numerous territoriality coexist with remarkably similar people who contributed to research presented songs, raising the possibility that character in this symposium, including Adam Baker, convergence has been driven by competitive Santiago Claramunt, Martin Cody, Travis interactions. This fits with evidence from Collier, Zachary Harlow, Robert Ricklefs, Hypocnemis antbirds that competing species Charles Taylor, Janeene Touchton, Edgar use convergent male songs to defend Vallejo. We are also grateful to numerous field territories against heterospecifics (Tobias and ornithologists, collectors and institutions for Seddon 2009b). Moreover, even though such providing vocalizations, specimens and tissues songs also function in mate attraction (Tobias used in these studies. et al. 2011), their convergent design does not lead to hybridization because females References are adept at discriminating between species and even individuals on the basis of subtly Badyaev AV, Young RL, Oh KP, Addison C, 2008. different vocalisations (Seddon and Tobias Evolution on a local scale: Developmental, 2010). These lines of evidence suggest that functional, and genetic bases of divergence

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