Genotoxic damage data from wild birds across high-altitude Andean cities (Ecuador)
Description
1. Research Hypothesis High-altitude tropical cities represent understudied systems where natural stressors associated with elevation (intense UV radiation, hypoxia, cold stress) and urbanization-related pressures (air pollution, impervious surfaces, vehicular emissions) may combine to amplify genotoxic damage in wildlife beyond what either factor would produce alone. We hypothesized that wild birds inhabiting high-altitude Andean cities (>2,000 m a.s.l.) would exhibit elevated frequencies of micronuclei and nuclear abnormalities compared to: (a) rural sites within the same cities, and (b) published benchmark values from lowland South American cities. Furthermore, we predicted that altitude would establish a baseline level of genetic damage that urbanization subsequently amplifies, potentially creating previously unrecognized genotoxic hotspots in high-elevation tropical urban environments. 2. What This Data Shows This dataset contains individual-level genotoxicity measurements from 43 wild birds belonging to 7 species, sampled across 4 Ecuadorian Andean cities (Loja, Cuenca, Quito, and Ibarra) at elevations ranging from 2,068 to 2,780 meters above sea level. Within each city, birds were captured from paired urban sites (parks, gardens, vacant lots) and rural sites (anthropic grasslands), allowing direct urban-rural comparisons. The core data includes: Micronucleus (MN) counts per 10,000 erythrocytes examined per individual Nuclear abnormality (NA) counts per 10,000 erythrocytes, broken down by type: Nuclear buds Notches Binucleated cells Species identification, city, site type (urban/rural), and environmental covariates
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Steps to reproduce
Field sampling (August–October 2024) Birds were captured using mist nets (80–120 linear meters per site; 12 m per net) Sampling effort: 6 days per city (3 urban, 3 rural); 5:30–10:30 AM Total effort: 178.2–270 net-hours per city Following capture, species were identified using Birds of Ecuador field guide (Freile & Restall, 2018) Blood sample collection ~50 μL blood collected via brachial vein puncture using insulin needle Blood transferred to microscope slide using 5–50 μL micropipette Smears prepared using wedge technique with coverslip at ~45° angle Fixed with absolute methanol, air-dried 3–5 minutes Stored protected from direct sunlight at room temperature Laboratory processing Slides rehydrated with PBS (2 mL, 5 minutes, 3 cycles) Air-dried ~1 hour Mounted with 80 μL Fluoromount-G with DAPI (Thermo Fisher Scientific) Screening performed by single observer; 10% random subset validated by second observer Microscopy and scoring Zeiss Axio Observer 7 fluorescence inverted microscope 100× oil-immersion objective 10,000 erythrocytes examined per individual Zig-zag scanning pattern with 2-field skip between analyzed fields to minimize spatial autocorrelation Classification followed Baesse et al. (2015) and Cevallos-Solorzano et al. (2023): Normal: Oval nucleus, intact membrane, no distortions Micronucleus: Small formation, diameter 1/16–1/3 of main nucleus, same focal plane, homogeneous fluorescence Nuclear bud: Protrusion emerging from main nucleus Notch: Marked indentation in nuclear perimeter Binucleated: Two nuclei of similar size within erythrocyte membrane
Institutions
- Universidad Técnica Particular de LojaLoja, Loja