Research Interests
My main interest is studying the factors promoting hummingbird diversity in South America. Specifically, I study phylogeographic patterns of hummingbird species in the Andes, paying particular attention to the role of geography, natural selection, and genetic drift in differentiating the populations of the Speckled Hummingbird (Adelomyia melanogenys). The impressive latitudinal range this hummingbird exhibits (Andes of Venezuela to Bolivia) makes it suitable to examine mechanisms promoting genetic and morphologic differentiation in the different habitats where it is found along the cordillera and at different elevations.
Phylogeography in the Andes
One part of my doctorate research deals with the identification of the factors promoting genetic diversity and morphological differentiation in this species along broad geographical ranges. Geography may have played an important role in isolating populations by volcanism and tectonics. Mechanisms like drift and natural selection may have acted upon these populations, shaping morphotypes in different habitats and across elevations producing the contemporary subspecies (six) and morphs observed in my previous work.
Subspecies Adelomyia melanogenys melanogenys from east Ecuadorian and Peruvian Andes (A),
A. m. maculata from west Ecuadorian Andes (B), and A. m. inornata from the Andes of Bolivia (C)
Speciation Modeling and Conservation
In collaboration with the NASA/Jet Propulsion Laboratory, I am generating distributional images which will contain patterns of genetic diversity, morphological differentiation, and physiological adaptation to examine the underlying effects of the various mechanisms responsible for the patterns observed and relate them to detailed habitat characteristics and to geography. I will be able to identify particular geographical regions and gradients where these differentiations and adaptations are produced and maintained and where conservation efforts should be allocated to preserve evolutionary processes in the Tropical Andes region.
By mapping the genetic distribution along its distributional range, I can examine the importance of geographical events on hummingbird patterns of biodiversity.
Ecological modelling for the Speckled Hummingbird in Ecuador based on
various climatic and environmental variables from satellite data
The Effects of Elevation on Flight Mechanics
Elevational gradients are of particular interest to me because they present a unique scenario where different selection regimes can act within relatively short distances, creating a mosaic of selecting agents as one examines populations up and down the gradient. In particular, I am interested in the effect of elevation on the flight mechanics of the hovering flight of the Speckled Hummingbird. In my past research, I have found that hummingbirds at higher elevations, such as 3000 m, modulate their flight as a response to the hypoxic and hypobaric conditions, compared to a the lower energy hovering flight of their conspecifics at lower elevations.
I am conducting a complete sampling of this species along the Andes in South America as well as recording hovering flight at different sites to determine the effect of elevation on behavioral traits. I will start looking at the genetics of these differentiations, targeting candidate genes that could be responsible for these phenotypic and physiological adaptations along its range.
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Left: Flight ecophysiology of the Speckled Hummingbird; Right: Cloud Forest in Manu National Park, Peru
Publications
Chaves, J.A., John P. Pollinger, Thomas B. Smith, Gretchen LeBuhn. 2007. The Role of Geography and ecology in Shaping the Phylogeography of the Speckled Hummingbird (Adelomyia melanogenys) in Ecuador. Molecular Phylogenetics and Evolution 43: 795-807. PDF.
Chaves, J.A., Juan F. Freile.2005. Aves Comunes de Otonga y los Bosques Nublados Noroccidentales del Ecuador. Fundacion Otonga, Ecuador.
Chaves, J.A. 2004. Phylogeography, evolution and flight ecophysiology of the Speckled Hummingbird (Adelomyia melanogenys) in Ecuador. Master Thesis Degree. Department of Biology. San Francisco State University, San Francisco CA.
Freile, J.F. M. Moreano, E. Bonaccorso, T. Santander y J. A. Chaves. 2004. Notas sobre la historia natural, distribución y conservación de algunas especies de aves amenazadas del suroccidente de Ecuador. Cotinga (21): 18-24. PDF.
Freile, J.F. and J. A. Chaves. 2004. Interesting distributional records and notes on the biology of bird species from a cloud forest reserve in north-west Ecuador. Bulletin of the Brithish Ornithologists' Club. 124 (1): 6-16. PDF.
Rampón B. and J. A. Chaves. 2004. Quinde, Hummingbirds of Ecuador. Barcelona 2004.
Freile, J.F., J. A. Chaves, G. Iturralde and E. Guevara. 2003. Notes of the distribution, habitat and conservation of the cloud-forest pygmy-owl (Glaucidium nubicola) in Ecuador. Ornitología Neotropical 14: 275-278.
Chaves, J. A. . 2001. Comparación de avifaunas en dos bosques nublados del Chocó ecuatoriano. Epiphytes and canopy Fauna of the Otonga Rain Forest (Ecuador) Nieder, J. & Barthlott, W (eds.). Vol 2. pag: 311 – 326.
Chaves, J. A. . 2001. Selección de hábitat y conducta alimenticia de aves frugívoras en dos bosques nublados de las estribaciones occidentales de los Andes del Ecuador. Licenciatura thesis degree, Departamento de Biología, Pontificia Universidad Católica del Ecuador, Quito, Ecuador.
Chaves, J. A. . 2000. Use of Cecropia and Ficus trees by fruit-eating birds in Ecuadorian chocoan andean cloud forests. 3rd International Symposium-Workshop on Frugivores and Seed Dispersal, Biodiversity and Conservation Perspectives.
Freile, J. F. y J. A. Chaves. 2000. Field observations on copulation by White-rumped Hawk, Buteo leucorrhous. Cotinga 14: 12.
Freile, J. F. y J. A. Chaves. 1999. Photospot: Colombian Screech-Owl, Otus ingens colombianus. Cotinga 12: 95-96.
Cresswell, W., S. Yerokhov, N. Berezovikov, R. Mellanby, S. Bright, P. Catry, J. Chaves, J. Freile, A. Gretton, A. Zykin, R. McGregor y D. McLaughlin. 1999. Important wetlands in northern and eastern Kazakhstan. Wildfowl 50: 181-194.
Cresswell, W., M. Hughes, R. Mellanby, S. Bright, P. Catry, J. Chaves, J. Freile, A. Gabela, H. Martineau, R. MacLeod, F. McPhie, N. Anderson, S. Holt, S. Barabas, C. Chapel y T. Sánchez. 1999. Densities and habitat preferences of Andean endemic birds in pristine and degraded habitats in Northeastern Ecuador. Bird Conservation International 9: 129-145.
Cresswell, W., R. Mellanby, S. Bright, P. Catry, J. Chaves, J. Freile, A. Gabela, M. Hughes, H. Martineau, R. MacLeod, F. McPhie, N. Anderson, S. Holt, S. Barabas, C. Chapel y T. Sánchez. 1999. Bird of the Guandera Reserve, Carchi province, northeastern Ecuador Ecuador. Cotinga 11: 55-63.
Chaves, J. A. y J. F. Freile. 1999. Kazajstán: de escenarios perdidos a sueños olvidados. Revista Domingo-El HOY, Julio 1999: 16-18.
Web Contributions
2006 Hummingbird Research. Mariri Magazine. Freelance Writer. "To Catch a Hummingbird." www.mariri.net/content/view/15/1
Some of my illustrations from the plates of the field guide to the birds of Northwestern Cloud Forest of Ecuador