Fecal corticosterone metabolite levels in two closely related rodent species in a sub-Mediterranean environment
Data files
Jun 02, 2025 version files 433.85 KB
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af_f_color.xls
28.16 KB
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af_m_color.xls
28.16 KB
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Apodemus_spp.R
7.88 KB
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as_f_color.xls
28.16 KB
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as_m_color.xls
28.16 KB
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dataset_flavicollis.xls
96.26 KB
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dataset_sylvaticus.xls
55.30 KB
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dataset.xls
125.44 KB
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README.md
8.18 KB
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stability.xls
28.16 KB
Abstract
Glucocorticoids regulate many physiological functions and play an important role in coping with challenging stimuli. The non-invasive assessment of glucocorticoids is increasingly used as a tool to evaluate individual and population health status in wild animals. Given the crucial role of rodents in forest ecosystems, it may be useful to study the glucocorticoid profile of these species to find possible links with the environmental characteristics in which they live and facilitate the development of biodiversity management plans. We studied two closely related species that are the main representatives of the ground-dwelling rodent communities in sub-Mediterranean forested areas: Apodemus sylvaticus and A. flavicollis. Fecal corticosterone metabolite (FCM) levels of animals captured in a Mediterranean agroforestry system were assessed. We found that A. sylvaticus males excreted lower FCM levels than females, while A. flavicollis males showed higher FCM levels than females. Males of the two species excreted similar FCM levels, while higher FCM levels were recorded in A. sylvaticus females than in their A. flavicollis counterparts. The FCM levels in both species were similar between breeding conditions, seasons, and habitat types. The results of our exploratory investigation suggest that traditional silviculture may not trigger the activity of the hypothalamus-pituitary-adrenal axis. Further studies are required for a more detailed examination of how environmental factors affect FCM levels. Long-term studies may disclose possible effects of interannual environmental factor variability in ground-dwelling rodents.
https://doi.org/10.5061/dryad.5tb2rbpf0
Description of the data and file structure
The datasets as_f_color.xls, as_m_color.xls, af_f_color.xls, af_m_color.xls, and stability.xls were used to evaluate fecal corticosterone metabolites levels time excretion and stability differences postexcretion. The datasets dataset.xls, dataset_flavicollis.xls and dataset_sylvaticus.xls were used to investigate the effects of individual (i.e. sex and breeding condition) and environmental (i.e. season and habitat type) variables on the fecal corticosterone metabolite levels in Apodemus sylvaticus and Apodemus flavicollis
Files and variables
File: af_f_color.xls
Description: Female Apodemus flavicollis uncolored and colored fecal boluses collected from the live-trap
Variables
- IDanimal: number of the trap and date of animal capture
- type: type of fecal boluses, uncolored = fecal boluses that did not have any trace of colored wax marker; colored = boluses with marked evidence or wax colored traces
- species: species of the animals; AF = Apodemus flavicollis
- sex: sex of the animals
- FCM: fecal corticosterone metabolite concentration (ng/g)
- logFCM: log-transformed fecal corticosterone metabolite concentration (ng/g)
File: af_m_color.xls
Description: Male Apodemus flavicollis uncolored and colored fecal boluses collected from the live-trap
Variables
- IDanimal: number of the trap and date of animal capture
- type: type of fecal boluses, uncolored = fecal boluses that did not have any trace of colored wax marker; colored = boluses with marked evidence or wax colored traces uncolored or colored boluses
- species: species of the animals; AF = Apodemus flavicollis
- sex: sex of the animals
- FCM: fecal corticosterone metabolite concentration (ng/g)
- logFCM: log-transformed fecal corticosterone metabolite concentration (ng/g)
File: as_f_color.xls
Description: Female Apodemus sylvaticus uncolored and colored fecal boluses collected from the live-trap
Variables
- IDanimal: number of the trap and date of animal capture
- type : type of fecal boluses, uncolored = fecal boluses that did not have any trace of colored wax marker; colored = boluses with marked evidence or wax colored traces
- species: species of the animals; AS = Apodemus sylvaticus
- sex: sex of the animals
- FCM: fecal corticosterone metabolite concentration (ng/g)
- logFCM: log-transformed fecal corticosterone metabolite concentration (ng/g)
File: as_m_color.xls
Description: Male Apodemus sylvaticus uncolored and colored fecal boluses collected from the live-trap
Variables
- IDanimal: number of the trap and date of animal capture
- type: type of fecal boluses, uncolored = fecal boluses that did not have any trace of colored wax marker; colored = boluses with marked evidence or wax colored traces
- species: Species of the animals; AS = Apodemus sylvaticus
- sex: sex of the animals
- FCM: fecal corticosterone metabolite concentration (ng/g)
- logFCM: log-transformed fecal corticosterone metabolite concentration (ng/g)
File: stability.xls
Description: Pool fecal samples left at ambient temperature before to be stored at -20°C to evaluate the stability of fecal corticosterone metabolite levels during the time windows of the test
Variables
- time_h: Number of hours the samples remained after their excretion at ambient temperature before to be stored at -20°C
- id: Id number of the pool used to prepare the aliquots
- FCM: fecal corticosterone metabolite concentration (ng/g)
- logFCM: log-transformed fecal corticosterone metabolite concentration (ng/g)
File: dataset_sylvaticus.xls
Description: Dataset of the Apodemus sylvaticus capture in the Selva forest between September 2011 and September 2012
Variables
- Session: Session of capture
- Season: Season of capture, hot : spring-summer period (May, July, and September); cold: autumn-winter (January, March, and November)
- Date: date of capture (YYMMDD)
- Grid: Grid of capture
- Habitat: Habitat type of capture, woodland: coppiced deciduous woodland, fallow: fallow field, conifer plantation: conifer plantation
- Species: Species of the animal
- Mark: Id of the captured animal
- Weight_g: Weight of the animal at capture (g)
- Sex: Sex of the animal
- Testes: visible size of the test for male animals (A = abdominal; S = small; L = large) ; NA for female animals
- Pregnant: No or Yes for female animals; NA for male animals,
- Nipples: Visible size of the nipples for female animals (N= non visible; S= small; B = big); NA for male animals
- Vagina: Opening of vagina (C= close; O = open); NA for male animals
- Breeding: Breeding condition of the animals (Yes = females with opened vagina and/or small or big nipples, males with small or large testes; No = females with closed vagina and no visible nipples, males with abdominal testes)
- FCM_ng: Fecal corticosterone metabolite levels (ng/g)
- log_FCM: log-transformed fecal corticosterone metabolite concentration (ng/g)
File: dataset_flavicollis.xls
Description: Dataset of the Apodemus flavicollis capture in Selva forest between September 2011 and September 2012
Variables
- Session: Session of capture
- Season: Season of capture, hot : spring-summer period (May, July and September); cold: autumn-winter (January, March, and November)
- Date: date of capture (YYMMDD)
- Grid: Grid of capture
- Habitat: Habitat type of capture, woodland: coppiced deciduous woodland, fallow: fallow field, conifer plantation: conifer plantation
- Species: Species of the animal
- Mark: Id of the captured animal
- Weight_g: Weight of the animal at capture (g)
- Sex: Sex of the animal
- Testes: visible size of the test for male animals (A = abdominal; S = small; L = large) ; NA for female animals
- Pregnant: No or Yes for female animals; NA for male animals,
- Nipples: Visible size of the nipples for female animals (N= non visible; S= small; B = big); NA for male animals
- Vagina: Opening of vagina (C= close; O = open); NA for male animals
- Breeding: Breeding condition of the animals (Yes = females with opened vagina and/or small or big nipples, males with small or large testes; No = females with closed vagina and no visible nipples, males with abdominal testes)
- FCM_ng: Fecal corticosterone metabolite levels (ng/g)
- log_FCM: log-transformed fecal corticosterone metabolite concentration (ng/g)
File: dataset.xls
Description: Dataset of the Apodemus sylvaticus and A. flavicollis captured in Selva forest between September 2011 and September 2012
Variables
- Session: Session of capture
- Season: Season of capture, hot : spring-summer period (May, July, and September); cold: autumn-winter (January, March, and November)
- Date: date of capture (YYMMDD)
- Grid: Grid of capture
- Habitat: Habitat type of capture, woodland: coppiced deciduous woodland, fallow: fallow field, conifer plantation: conifer plantation
- Species: Species of the animal
- Mark: Id of the capture animal
- Weight_g: Weight of the animal at capture (g)
- Sex: Sex of the animal
- Testes: visible size of the test for male animals (A = abdominal; S = small; L = large) ; NA for female animals
- Pregnant: No or Yes for female animals; NA for male animals,
- Nipples: Visible size of the nipples for female animals (N= non visible; S= small; B = big); NA for male animals
- Vagina: Opening of vagina (C= close; O = open); NA for male animals
- Breeding: Breeding condition of the animals (Yes = females with opened vagina and/or small or big nipples, males with small or large testes; No = females with closed vagina and no visible nipples, males with abdominal testes)
- FCM_ng: Fecal corticosterone metabolite levels (ng/g)
- log_FCM: log-transformed fecal corticosterone metabolite concentration (ng/g)
Code/software
Programm used R version 4.4 or Rstudio version 2024.12.0
Script: Apodemus_spp.R
To evaluate the effects induced by different habitat types on mouse FCM levels we selected fifteen sampling sites within the three main habitat types: coppiced deciduous woodlands, conifer plantations and long-fallow fields.
Trapping sessions were conducted every other month from September 2011 to September 2012. In each sampling site, handmade LOT (Locasciulli Osvaldo Trap) live traps (9 x 8 x 23 cm) (Locasciulli et al. 2015), were placed on a 60 x 60 m grid. The grids were placed at least 100 m away from the habitat border. The minimum distance between two grids was around 500 m. The traps were equipped with nesting material (hemp) and baited with sunflower seeds, apples, and peanut butter. In each session, the traps were checked every morning for three consecutive days.
To evaluate the effects induced by trap confinement on mouse FCM levels and post-excretion FCM stability, opportunistic trapping events were carried out using food-baited L.O.T. traps placed in transects (20 traps, 10 m spacing). In particular, to test if the time mice spent in the traps was longer than their gut transit time, we added shredded colored waxes (Giotto be-bè®, Fila, Spain) to the bait as indigestible nontoxic markers (Serres-Corral et al. 2021). Traps remained active for three consecutive nights and were checked every morning.
The use of shredded colored waxes made it possible to distinguish the fecal boluses excreted in the trap before the digestion of the bait (i.e. boluses excreted in the 8-10 hours following capture) from those excreted afterwards. Almost all of the animals captured (around 90%) excreted both uncolored and colored fecal boluses inside the traps. The FCM levels of uncolored and colored fecal samples were assessed separately to compare their values (A. sylvaticus: 10 males and 10 females; A. flavicollis: 10 males and 9 females).
A possible influence of factors such as temperature, humidity, and bacterial enzymes on the types and concentrations of fecal glucocorticoid metabolites after defecation has been described in some mammal species (Touma & Palme 2005). For this reason, certain studies assessing FCM levels in wild rodent species (e.g. Navarro-Castilla et al. 2014; Navarro-Castilla & Barja 2014) chose to collect only fresh fecal boluses (i.e. only feces with a soft texture) to avoid any issues regarding hormone metabolite stability. However, no data are available on the post-excretion stability of hormone metabolites in mice. To evaluate post-excretion FCM level stability, we collected fresh boluses excreted by the mice during handling for identification. The boluses of different animals from both species and sexes were mixed to obtain several sample pools (n = 6) for statistical analyses. Each pool was mixed to be homogeneous and five aliquots of 100 mg were taken from each pool for sampling. One aliquot from each set was immediately frozen at -20 °C while the others were left at ambient temperature for different time periods (6, 12, 18, 24 h) before being stored at −20 °C until hormone extraction was carried out.