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Why Cities?
Cities represent some of the most rapidly altered environments on our planet: light, noise, chemical pollutants, and heat pose challenges to living systems, with broad implications across scales of biological organization. Nonetheless, many species rapidly adapt, persist, and even thrive in urban landscapes, presenting an opportunity to test hypotheses about the factors that facilitate or constrain evolutionary responses to novel conditions. We leverage cities as a natural experiment to describe how phenotypic, ecological, and evolutionary processes interact to produce variation in responses to urbanization change across individuals, populations, and species.
Organismal responses
What makes one individual more successful than another? What are the costs and benefits of different strategies that an individual might employ to cope with a novel disturbance? At the organismal level, we ask how behavior, physiology, and genetics interact to produce the variation in responses to anthropogenic change, and ultimately variation in fitness.
vid_hum.mp4Hummingbird responses to urban heat
Hummingbird responses to urban heat
Hummingbirds have the highest mass-specific metabolic rate of any animal and live paycheck to paycheck with their calories, leaving little room for error. Changes in climate or resources can therefore have a huge impact on their survival. I are currently using a combination of field respirometry, camera trapping, geometric morphometrics, spectrophotometry, and thermal imaging to understand the behavioral and physiological strategies that hummingbirds use to cope with urban heat. We are then using whole-genome sequencing to infer the genetic basis of traits that increase thermal tolerance or flexibility.
This work is currently funded by a National Science Foundation Postdoctoral Fellowship in Biology.
Green-throated Carib, San Juan, PR.
Alyssa Sargent and Valentina working in one of our favorite backyards, Fall 2023.
Puerto Rican Mango (male). Red marking on the crown is a small dot of non-toxic fabric paint that we place to identify and avoid recapturing the same individual.
Artificial Light at Night
tl;dr Check out this podcast and comedy-show-turned-podcast where Valentina talk about ALAN and birds!
For 4 billion years life has evolved under dark nights, brightened only by the moon and stars. As consequence, mechanisms for detecting and responding to patterns of light and dark exist in all organisms and play a key role in the timing of cyclic behavioral and physiological processes. Artificial light at night (ALAN) disrupts these natural photoperiodic cues, and has consequences for behavior, physiology, health, and ecosystem function. We use controlled laboratory experiments to understand the effects of light pollution in isolation from other urban stressors, and describe the mechanisms by which night light affects behavior, physiology and health.
Using zebra finches (Taeniopygia guttata) as a model, our work has shown that light pollution exposure alters behavior, endocrine systems, cardiovascular plasticity, and oxidative balance, and that the magnitude of response depends on spectral composition. We demonstrated these responses can occur independently from the pacemaker genes that regulate circadian rhythms, and that behavioral and physiological responses are flexible, with individuals demonstrating partial recovery as well as habituation over time.
We also went on to map immediate early gene expression in the brain during exposure to night-light using immunocytochemistry.
As we travel outward from a city, changes in the abiotic and biotic environment are rapid and extreme. However, there is also a mosaic environmental heterogeneity within cities. Resources and environmental challenges vary in space, time, and intensity, and the layout of this variation reflects a city's design, human culture, and history.
Luxury Effects on Biodiversity
The distribution of green space in cities often reflects the human socioeconomic landscape - variables such as household income and historical redlining predicting which parts of the cities have more trees, parks, etc. This can lead to a “Luxury Effect” where biodiversity is positively correlated with surrounding affluence. Our lab studies how the socioeconomic landscape effects urban wildlife. Check out this blog post, article in the Gothamist (and WNYC Radio), and short video highlighting some of this work ongoing in New York City.
Global patterns of evolutionary potential and convergence.
We take advantage of cities world-wide as replicated experiments to investigate how environmental context shapes the evolutionary outcomes of urbanization and identify factors that facilitate or constrain species convergence. I am currently establishing parallel urban systems across the Americas to test how geographic context affects the rate and magnitude of local adaptation to cities. Latin America represents the second most urbanized global region, with 81% of habitants living in urban areas, and contains over 40% of the world’s avian biodiversity, yet current knowledge about the effect of urbanization on organisms is biased toward temperate regions (e.g. North America and Europe) with fewer studies focused in the tropics. This work also works towards rectifying global biases in knowledge, elevating research & researchers in Central and South America, and helping narrow the hemispheric gap that divides our science.
This part of my research is still building - stay tuned as I build parallel urban field systems in Puerto Rico, New York, Seattle, Colombia (Bogotá and Fusagasugá), Panama (Panama City and Gamboa), and Chile (Santiago).
I am always looking for community members to help me study hummingbirds. If you live in any of these cities (or surrounding rural areas), see hummingbirds around, and want to help me study them - send me an email! I would be extra excited if you have hummingbird feeders or would be interested in starting to maintain one.
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