Data and code from: How a territorial challenge changes sex steroid-related gene networks in the female brain: A field experiment with the tree swallow
Data files
Mar 31, 2025 version files 41.35 KB
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data_bird.csv
995 B
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data_br.csv
5.64 KB
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George_and_Rosvall_H_B_2025.R
30.23 KB
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network_layout.csv
326 B
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README.md
4.15 KB
Abstract
Territorial competition can stimulate secretion of testosterone (T), which is thought to act on neural circuits of aggression to promote further aggression. Here, we test the hypothesis that competition modulates sex steroid sensitivity and conversion in the brain, focused on the female tree swallow (Tachycineta bicolor). In this bird species, exogenous T enhances female aggression, but social competition for limited nesting territories does not stimulate systemic T elevation. We exposed free-living females to simulated territorial intrusions and sampled five regions of the vertebrate social behavior network (SBN). Using quantitative PCR, we measured mRNA abundance of: androgen receptor, 5-alpha reductase, estrogen receptor alpha, and aromatase. Using standard analyses, we found essentially no treatment effect on mRNA abundance in any one brain area; however, network analyses revealed marked socially-induced changes in gene co-expression across the SBN. After a territorial challenge, gene expression was more positively correlated with T, and genes specific to the androgen-signaling pathway were also more positively correlated with one another. The challenged brain also exhibited stronger negative correlations among genes in the nucleus taeniae, but stronger positive correlations between the lateral septum and bed nucleus of the stria terminalis. Together, these findings suggest that, in response to female-female territorial challenges, T acts on androgen-mediated circuits of aggression, with some divergence in gene regulation in the nucleus taeniae. The post-transcriptional consequences of these shifts require more research, but their existence underscores insights to be gained from analyzing the neuroendocrine properties of the SBN using network-level perspectives.
Dataset DOI: 10.5061/dryad.69p8cz9dv
Description of the data and file structure
This study was conducted on female tree swallows breeding in bird boxes in Linesville, PA, in spring 2019. Females were either exposed to a 30-minute simulated territorial intrusion (STI) or belonged to the control treatment group (n=10 each). Aggressive behavior was recorded during the first 5 minutes of each STI. 2 to 3 hours after the end of the STI, females were captured and collected for tissue samples. Circulating blood was collected for measuring testosterone concentrations (via a high-sensitivity ELISA kit- Enzo #ADI-900-176). Each female’s whole brain was removed and flash-frozen on dry ice. Later, brains were microdissected to obain RNA from 5 nodes of the social behavior network: BnST= bed nucleus of the stria terminalis, LS= lateral septum, NT= nucleus taeniae, POA= preoptic area of the hypothalamus, VMH= ventral medial hypothalamus. qPCR was used to measure relative mRNA abundance for four genes of interest: androgen receptor, estrogen receptor alpha, aromatase, and 5-alpha reductase.
Files and variables
File: data_bird.csv
Description: The data table is organized such that one row represents one female bird. Includes capture details and circulating T concentrations for all females, as well as behavioral measurements from birds in the STI treatment group
Variables
- Female ID: unique identifier for each bird collected in the study
- Treatment: STI (exposed to simulated territorial intrusion) or control
- julian date: date of collection, as day of year (Jan 1= 1)
- Capture_time: time of day when bird was captured and euthanized (hh:mm am/pm)
- Mass_g: body mass measured at time of capture/collection, in grams
- ng T/mL plasma: circulating testosterone concentration (nanograms of T per milliliter of plasma), as measured via an ELISA from hormones extracted from blood plasma collected after decapitation
- any agg 5s bins (1st 5min): aggression score measuring how females in the STI treatment group responded to the simulated intruder; the number of 5-second time bins containing any aggressive behavior (see Bentz et al. Ethology, 2019)
- STI_to_cap_h: latency from the end of the 30-minute STI to capture, in hours
File: data_br.csv
Description: Data table is organized such that one row represents one biological sample on which qPCR was performed (i.e., one brain region).
Variables
- Female ID: unique identifier for each bird collected in the study
- Treatment: STI (exposed to simulated territorial intrusion) or control
- brain region: microdissection region of the social behavior network; BnST= bed nucleus of the stria terminalis, LS= lateral septum, NT= nucleus taeniae, POA= preoptic area of the hypothalamus, VMH= ventral medial hypothalamus
- Sample Name: unique identifier for each micro-dissected brain region from each individual
- ct GAPDH: raw qPCR results (threshold cycle) for housekeeper gene GAPDH
- ct PPIA: raw qPCR results (threshold cycle) for housekeeper gene PPIA
- RQ 5aRed: relative quantification of 5-alpha reductase gene; calculated using the 2-∆∆CT method
- RQ AR: relative quantification of androgen receptor gene; calculated using the 2-∆∆CT method
- RQ AROM: relative quantification of aromatase gene; calculated using the 2-∆∆CT method
- RQ ERa: relative quantification of estrogen receptor alpha gene; calculated using the 2-∆∆CT method
File: George_and_Rosvall_H_B_2025.R
Description: R script for reproducing statistical results and figures
File: network_layout.csv
Description: X and y coordinates for each node of network graphs (Figure 4)
Variables
- label: network node (brain region- gene combination, or circulating T)
- x: x coordinate
- y: y coordinate
Code/software
George and Rosvall H&B 2025.R run with R (version 4.1.1)
Packages required are specified within the above R script.