National University of Colombia
Morphological changes in birds over time.
Several studies in birds have found that habitat transformation and climate change are associated with morphological changes over short periods of time (40–130 years), resulting in narrower and pointier wings (Gardner et al. 2009, Gardner et al. 2011, Hermes et al. 2016, Onley et al. 2020) or a decrease in mass and an increase in wing length (Jirinec et al. 2021). These morphological changes have been suggested to be adaptations that improve flight capability and resource economy in transformed environments. As part of my doctoral dissertation, I am building on this set of studies by investigating avian morphological variation in a specimen time series of over 100 years across seven Colombian localities. The specimens for this project were collected in Colombia by personnel of the American Museum of Natural History (AMNH), led by Frank Chapman, between 1911 and 1913, and recent specimens are from seven "Chapman sites” visited between 2019 and 2023 as part of the Colombia Resurvey Project.
Advances
Between January and February 2024, I visited the AMNH, where I examined and measured 617 specimens collected over 100 years ago in Colombia.
Back in Colombia, I then examined and measured 819 specimens collected between 2019 and 2023 at the same sites previously visited by AMNH researchers.
In a first approach to estimate the morphological changes of birds over the last century, I have focused on exploring the data from the locality of Barbacoas. This is due to its exceptional landscape conservation, which allows us to examine whether morphological changes are related to changes in climate.
So far, we have found significant changes in body size and structures such as bills, wings, and tails in birds from Barbacoas through time. The results of this first approach are part of a manuscript in review for publication in the special issue “Morphological responses to climate change” of the journal Evolutionary Ecology.
Exploring patterns of isolation and connection between disjunct trans-Amazonian populations of a savanna-associated bird.
Disjunct geographic ranges within species are due to many factors, including habitat requirements, dispersal ability, and historical population dynamics (Socolar et al. 2018). An interesting pattern of disjunct ranges occurs across many species found in dry forests and savannas of South America. These habitats are found on the northern and southern borders of the Amazon Basin and thus have a trans-Amazonian distribution (Silva & Bates et al. 2022). Paleoclimatic estimates and biotic similarity demonstrate that these savannas may have been connected at the end of the Pleistocene through three main corridors (Silva & Bates et al. 2022): I) an Andean corridor, II) a Central corridor, and III) a Coastal corridor. To provide further insights into the evolutionary connections among isolated bird populations in the savannas of South America, I am generating a large genomic dataset for a savanna-specialist bird, Hemitriccus striaticollis. This species has a largely trans-Amazonian distribution that also includes several isolated populations embedded in dry inter-Andean valleys and the Amazon Basin. I will use data from across the genome to evaluate historical patterns of gene flow between currently isolated populations. I will complement genetic analyses with morphological and vocal data to help understand the evolutionary relationships among intraspecific populations.