Are urbanization and brood parasitism associated with differences in telomere lengths in song sparrows?
Data files
Jul 15, 2024 version files 20.54 KB
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README.md
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rTLDryad.masterfile.csv
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Abstract
Urbanization reflects a major form of environmental change impacting wild birds globally. Whereas urban habitats may provide increased availability of water, some food items, and reduced predation levels compared to rural, they can also present novel stressors including increased light at night, ambient noise, and reduced nutrient availability. Urbanization can also alter levels of brood parasitism, with some host species experiencing elevated levels of brood parasitism in urban areas compared to rural areas. Though the demographic and behavioral consequences of urbanization and brood parasitism have received considerable attention, their consequences for cellular-level processes are less understood. Telomeres provide an opportunity to understand the cellular consequences of different environments as they are a well-established metric of biological state that can be associated with residual lifespan, disease risk, and behaviour, and are known to be sensitive to environmental conditions. Here we examine the relationships between urbanization, brood parasitism, and blood telomere lengths in adult and nestling song sparrows (Melospiza melodia). Song sparrows are a North American songbird found in both urban and rural habitats that experience high rates of brood parasitism by brown-headed cowbirds (Molothrus ater) in the urban, but not the rural, sites in our study system. Among adults and nestlings from non-parasitized nests, we found no differences in relative telomere lengths between urban and rural habitats. However, among urban nestlings, the presence of a brood parasite in the nest was associated with significantly shorter relative telomere lengths compared to when a brood parasite was absent. Our results suggest a novel, indirect, impact of urbanization on nestling songbirds through the physiological impacts of brood parasitism.
rTLDryad.masterfile.csv
The data presented here is relative telomere length, and life history data collected from adult and nestling wild song sparrows (Melospiza melodia), and how they relate to urbanization, and brood parasitism by brown-headed cowbirds (Molothrus ater).
Description of the data and file structure
Code and data for Journal of Avian Biology Submission JAV-03220
Variables:
- plate - qPCR plate number
- Age.day - Age of nestlings in days since hatch, which is indicated by day zero
- Habitat - the habitat type that the individual was sample, either urban or rural
- SOSP.brood.size – number of song sparrow nestlings in a nest.
- Total.brood.size- Total number of nestlings in a nest, derived from adding number of song sparrows and number of brown headed cowbird nestlings in a given nest.
- rTL - Relative telomere length
- date - Calendar date the sample was collected.
- sex – sex of individual determined either through visual examination of physical characteristics or genotyping.
- Site - The individual research site the bird was sampled from.
- Age..year. - The age in years of the sampled bird. Within this, “HY” stands for “Hatch year” and means the bird was a nestling at time of sampling and been born that year and “ASY” stands for “After Second year” meaning the individual was an adult at time of sampling
- year = calendar year bird was sampled
- NID = Unique nest id given to every nest in the study.
- Para.comp = nests that are used for the brood parasitism comparison. Only included urban nests that were either parasitized, or not parasitized by brown headed cowbirds.
- Bhco.hab – categorizing nests within the brood brood parasitism comparison as either parasitized (urban.yes) or not parasitized (urban.no)
- nest.para - category defining if a nest was parasitized or was not parasitized by brown headed cowbirds.
- Nest.para.fig - used to filter nests for creating the nest parasitism figure.
Code/Software
Annotations are provided throughout the script, libraries need are included in the script and below.
CODE: Data Analysis for Dryad 09.11.23.R
Software: R Statistical Software v. 4.2.2.
Packages used
library(Rmisc)
library(tidyverse)
library(car)
library(lme4)
library(lmerTest)
library(lubridate)
library(glmm)
library(predictmeans)
library(lsmeans)
library(gridExtra)
library(effects)
library(emmeans)
library(broom)
library(modelr)
library(performance)
library(ggpubr)