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Extreme Endemic Radiation of the Malagasy Vangas (Aves: Passeriformes)

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Abstract

Phylogenetic relationships of the family Vangidae and representatives of several other passeriform families were inferred from 882 base positions of mitochondrial DNA sequences of 12S and 16S rRNA genes. Results indicated the monophyly of the Vangidae, which includes the genus Tylas, hitherto often placed in the family Pycnonotidae. Our results also revealed the Malagasy endemic Newtonia, a genus never previously assigned to the Vangidae, to be a member of this family. These results suggest the occurrence of an extensive in situ radiation of this family within Madagascar, and that the extant high diversity of this family is not the result of multiple colonizations from outside. The extremely high morphological and ecological diversification of the family seems to have been enhanced through the use and ultimate occupancy of vacant niches in this island.
... The few systematic studies of Malagasy birds have produced astounding findings, most prominently the discovery of the spectacular in situ radiation of the Malagasy Vangidae (Jønsson et al., 2012;Reddy et al., 2012). This monophyletic assemblage consists of at least 22 species, many of which were originally placed in other families, and is nearly as morphologically diverse as all passerines combined (Jønsson et al., 2012;Reddy et al., 2012;Yamagishi et al., 2001). Furthermore, a group of 11 species previously placed in three different families was found to represent another monophyletic avian assemblage endemic to Madagascar (Cibois et al., 2001), and now comprises the recently described family Bernieridae (Cibois et al., 2010). ...
... The genus Newtonia is a group of small, forest-dwelling songbirds endemic to Madagascar. Newtonia were originally classified as either Old World warblers (Sylviidae) or flycatchers (Muscicapidae), but are now known to belong to the Vangidae radiation (Reddy et al., 2012;Yamagishi et al., 2001). The current taxonomy delineates four species. ...
... Schetba, or the Rufous Vanga, is a monotypic genus within an endemic Malagasy radiation of songbirds, the Vangidae (Yamagishi et al., 2001;Reddy et al., 2012;Jønsson et al., 2012). The current taxonomy of the genus comprises a single species, S. rufa, with two subspecies: S. r. rufa (Linnaeus, 1766) and S. r. occidentalis (Delacour, 1931). ...
... However, the degree of divergence between these subspecies, which are based on slight differences in bill dimensions and plumage, has not been corroborated with genetic or ecological data. Previous genetic studies each included only a single representative of S. rufa (Yamagishi et al., 2001;Jønsson et al., 2012;Reddy et al., 2012). Furthermore, the distributional limits of S. r. occidentalis and S. r. rufa are somewhat ill-defined and might be attributed to clinal variation (Delacour, 1932;Schulenberg, 2013). ...
Article
Madagascar is known as a biodiversity hotspot, providing an ideal natural laboratory for investigating the processes of avian diversification. Yet, the phylogeography of Madagascar's avifauna is still largely unexamined. In this study, we evaluated phylogeographic patterns and species limits within the Rufous Vanga, Schetba rufa, a monotypic genus of forest-dwelling birds endemic to the island. Using an integrative taxonomic approach, we synthesized data from over 4000 ultra-conserved element (UCE) loci, mitochondrial DNA, multivariate morphometrics, and ecological niche modeling to uncover two reciprocally monophyletic, geographically circumscribed, and morphologically distinct clades of Schetba. The two lineages are restricted to eastern and western Madagascar, respectively, with distributions broadly consistent with previously described subspecies. Based on their genetic and morphological distinctiveness, the two subspecies merit recognition as separate species. The bioclimatic transition between the humid east and dry west of Madagascar likely promoted population subdivision and drove speciation in Schetba during the Pleistocene. Our study is the first evidence that an East-West bioclimatic transition zone played a role in the speciation of birds within Madagascar.
... For example, the Cretaceous-Paleogene mass extinction of the nonavian dinosaurs and other archosaurs resulted in an explosive radiation (a) The colonization of an isolated area (e.g., an island or lake) can provide a release from competition and predation pressures, allowing a clade to diversify into a variety of ecological niches from which they were previously blocked. For example, the colonization of Madagascar resulted in a spectacular adaptive radiation of Vangid birds (Yamagishi et al. 2001, Jønsson et al. 2012. Additional examples include Galápagos finches (Grant & Grant 2008), Hawaiian lobeliads (Givnish et al. 2009), African Rift Lake cichlids (Seehausen 2006), Hawaiian spiders (Gillespie 2004(Gillespie , 2015, Sulawesi silversides (Pfaender et al. 2010), and Caribbean Anolis lizards (Losos 2009). ...
... In several ways, molecular phylogenetics has been instrumental in the resurgence of the study of adaptive radiation and the role that ecological opportunity plays (Glor 2010). For example, molecular studies have revealed that many biotas previously assumed to be comprised of multiple ancestral lineages are the result of diversification of a single clade: Examples include the Malagasy vangas (Vangidae) (Yamagishi et al. 2001, Jønsson et al. 2012, Reddy et al. 2012); Australian, African, and global corvoids (Barker et al. 2004;Jønsson et al. 2011Jønsson et al. , 2015; Lake Victoria cichlids (Meyer et al. 1990); and Hawaiian lobeliads (Givnish et al. 2009). Molecular phylogenies have also proved useful in clarifying temporal patterns of diversification, which is important for understanding the pace of diversification (Rabosky 2009) and recognizing potential catalysts for adaptive radiation (Donoghue 2005, Glor 2010). ...
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The process of adaptive radiation—the proliferation of species from a single ancestor and diversification into many ecologically different forms—has been of great interest to evolutionary biologists since Darwin. From the middle of the last century, ecological opportunity has been invoked as a potential key to understanding when and how adaptive radiation occurs. Interest in the topic of ecological opportunity has accelerated as research on adaptive radiation has experienced a resurgence, fueled in part by advances in phylogenetic approaches to studying evolutionary diversification. Nonetheless, what the term actually means, much less how it mechanistically leads to adaptive diversification, is currently debated; whether the term has any predictive value or is a heuristic useful only for post hoc explanation also remains unclear. Recent recognition that evolutionary change can occur rapidly and on a timescale commensurate with ecological processes suggests that it is time to synthesize ecological and evolutionary approaches to the study of community assembly and evolutionary diversification.
... In contrast, phylogeographic studies associated with in situ differentiation on Madagascar, after colonization successfully took place, are uncommon and speciation patterns are still poorly understood for birds. Yamagishi et al. (2001) studied the species-level relationships among the Vangidae, an endemic radiation of Malagasy corvoids that probably dates back to the Oligocene (Fuchs et al. 2006). Marks and Willard (2005) recently addressed the geographic origin of the Madagascar Pygmy Kingfisher (Ispidina madagascariensis). ...
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A recent taxonomic revision of the Malagasy Scops-Owl (Otus rutilus) recognized two distinct endemic species on the island based on plumage, vocal, and morphological characters: O. rutilus (sensu stricto) from eastern humid forest formations and O. madagascariensis from western dry forest areas. An evaluation of these characters calls into question their validity for taxonomic studies, as they may be ecologically linked. To independently assess the two-species hypothesis, we used sequence data from 1449 base pairs (bp) of mitochondrial DNA (mtDNA) from 34 scops-owls obtained across the range of these two putative species. Nineteen haplotypes were detected, four of which were shared by more than one individual. Maximum sequence divergence was 0.6% (mean = 0.24%). While the most common haplotype was shared by 10 individuals originating from different eastern and western localities, 12 haplotypes were exclusive to O. rutilus and five to O. madagascariensis. An analysis of molecular variance showed significant partitioning of the genetic variability between O. rutilus and O. madagascariensis. The estimate of the divergence time between populations associated with the names O. rutilus and O. madagascariensis was 8070 years BP. Based on haplotype frequencies and sequence divergence, we conclude that there are two populations of Otus on Madagascar that started to diverge in recent geological time following an ecological parapatric model, perhaps associated with Quaternary climatic shifts. Using these results, it is inappropriate to recognize two species of Otus on Madagascar.
... Vangas exhibited rapid speciation following the initial colonization of the island by a shared ancestor and now provide a prime example of adaptive radiation, with considerable variation in body size and shape (Yamagishi et al. 2001;Jønsson et al. 2012;Reddy et al. 2012). These morphological differences can provide useful clues to the means by which sympatric congeners achieve ecological segregation according to food niche. ...
Article
The common ancestry of congeneric species implies that their morphology and ecology are similar, and thus that these closely related species may experience intensified levels of competition when sympatrically distributed. Under such circumstances, selective pressure may lead to niche partitioning between and within species, with segregation achieved through variation in morphology, ecology and life history. Examining the mechanisms underlying the coexistence or segregation of congeneric species requires detailed data on aspects of their ecology such as their feeding behaviour or habitat use. Endemic island birds, such as the vangas of Madagascar, are good candidates for studying processes of niche segregation. Vangas underwent rapid speciation following the initial colonization of the island by a shared ancestor and now provide a prime example of adaptive radiation, with considerable variation in body size and shape. Four small species of Newtonia are an exception to this variation, as they show morphological overlap and partial spatial range sympatry. Here, we describe the morphology of two Newtonia species, the Common Newtonia Newtonia brunneicauda and Dark Newtonia Newtonia amphichroa, with respect to their ecology and trophic niches using a multi-isotope approach (stable isotope ratios of carbon, nitrogen and sulphur). We report evidence for adaptations involving morphological feeding traits and provide data on contrasting trophic niches between two species with a close phylogenetic relationship. We document micro-habitat niche specialization that may be due to vertical stratification within the forest. Differences in feather isotopic signatures indicate different nutrient sources and point towards microhabitat segregation that is sufficient to maintain species integrity and permit coexistence.
... The Helmet Vanga Euryceros prevostii belongs to the family Vangidae, which contains 22 species in 15 genera (Jønsson et al. 2012). They are well-known for their ecological radiation, resembling that of the Hawaiian honeycreepers and the Galapagos finches (Yamagishi et al. 2001, Grant & Grant 2008, Jønsson et al. 2012, Reddy et al. 2012. The Helmet Vanga is one of the largest and most striking members of the Vangidae. ...
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To determine the mating system of the endemic Helmet Vanga Euryceros prevostii in Madagascar, its nest-building behavior was studied from 27 September to 11 October 2015 on the Masoala Peninsula, Northeastern Madagascar. We found one nest which was open cup-shaped placed on the horizontal branch of a tree. Two birds were individually identified through differences in the spot and shape of the mandible. The two birds (probably male and female) made the nest. This result suggests that the Helmet Vanga is a socially monogamous species.
... A sampling of recent findings within the passerines indicates that: -the southern origins of Oscine passerines is supported, with the New Zealand Wrens (Acanthisittidae) representing an ancient relict forming a sister group to all other passerines (Ericson et al. 2002a;Barker et al. 2002); -the monophyly of the two clades of New World suboscines is gaining clarification (Prum et al. 2000;Irestedt et al. 2001;Birdsley 2002), but with recent evidence demonstrating that two genera traditionally placed in Rhinocryptidae probably represent a separate family of uncertain relationships, the newly proposed Melanopareiidae ; -the lyrebirds (and probably scrub-birds) are the most basal group of the Oscines (Ericson et al. 2002b); -the Corvida of Sibley & Ahlquist (1990) is not monophyletic, but their Passerida is (Ericson et al. 2002a;Barker et al. 2002); -Madagascan taxa traditionally assigned to Pycnonotidae, Timaliidae and Sylviidae represent another ancient radiation comparable to the Vangidae, which also includes Newtonia (Fjeldså et al. 1999;Cibois et al. 1999Cibois et al. , 2001Yamagishi et al. 2001); -various New World nine-primaried Oscine taxa traditionally considered as finches prove to be tanagers and vice versa (Burns 1997;Seutin & Bermingham 1997;Groth 1998;Klicka et al. 2000;Lougheed et al. 2000;Garcia-Moreno et al. 2001;Sato et al. 2001;Yuri & Mindell 2002), while the Old World genus Emberiza is not a recent offshoot (Grapputo et al. 2001); -similar outcomes have been found with taxa traditionally considered thrushes or flycatchers, but in some cases their relationships apparently lie elsewhere (Pasquet et al. 1999(Pasquet et al. , 2002; see also Sorensen & Payne 2001); and -taxa traditionally placed in Paridae, Aegithalidae and Sylviidae are closely related (Sturmbauer et al. 1998). ...
... Recently, much progress has been made in understanding the timing and pattern of this important outcome of the process of evolution 8 , referred to as adaptive radiation, which has been shown to be as the main cause of the great diversification of ecological and morphological traits in a rapidly speciating group of organisms on islands 2 . To date, the majority of adaptive radiation studies are biased towards bird species from oceanic islands (interesting in this regard are the Galapagos finches, Hawaiian honeycreepers and lobeliads, the Gulf of Guinea white-eyes, the Australian corvoids or Madagascan vangids, and a plethora of others [9][10][11][12][13][14], mostly because they have occurred very recently and are readily accessible to scrutiny. However, we know relatively little about terrestrial-especially mammal-species to explain why some lineages undergo adaptive radiation and others do not [14][15][16][17] ; and is unclear how important adaptive radiation is over temporal scales that span large portions of the history of life 18 . ...
Article
Although the initial formulation of modern concepts of adaptive radiation arose from consideration of the fossil data, rigorous attempts to identify this phenomenon in the fossil record are largely uncommon. Here I focus on direct evidence of the diet (through tooth-wear patterns) and ecologically-relevant traits of one of the most renowned fossil vertebrates-the Miocene ruminant Hoplitomeryx from the island of Gargano-to deepen our understanding of the most likely causal forces under which adaptive radiations emerge on islands. Results show how accelerated accumulation of species and early-bursts of ecological diversification occur after invading an island, and provide insights on the interplay between diet and demographic (population-density), ecological (competition/food requirements) and abiotic (climate-instability) factors, identified as drivers of adaptive diversification. A pronounced event of overpopulation and a phase of aridity determined most of the rate and magnitude of radiation, and pushed species to expand diets from soft-leafy foods to tougher-harder items. Unexpectedly, results show that herbivorous mammals are restricted to browsing habits on small-islands, even if bursts of ecological diversification and dietary divergence occur. This study deepens our understanding of the mechanisms promoting adaptive radiations, and forces us to reevaluate the role of diet in the origins and evolution of islands mammals.
... Recently, much progress has been made in understanding the timing and pattern of this important outcome of the process of evolution 8 , referred to as adaptive radiation, which has been shown to be as the main cause of the great diversification of ecological and morphological traits in a rapidly speciating group of organisms on islands 2 . To date, the majority of adaptive radiation studies are biased towards bird species from oceanic islands (interesting in this regard are the Galapagos finches, Hawaiian honeycreepers and lobeliads, the Gulf of Guinea white-eyes, the Australian corvoids or Madagascan vangids, and a plethora of others [9][10][11][12][13][14], mostly because they have occurred very recently and are readily accessible to scrutiny. However, we know relatively little about terrestrial-especially mammal-species to explain why some lineages undergo adaptive radiation and others do not [14][15][16][17] ; and is unclear how important adaptive radiation is over temporal scales that span large portions of the history of life 18 . ...
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