Parasitism and alternative reproductive tactics in Northern chamois

Abstract

Alternative reproductive tactics (ARTs), discrete phenotypic variations evolved to maximize fitness, may entail different cost‐benefit trade‐offs. In large mammals, differences in costs associated with ARTs—including energy expenditure and parasite infection—are typically greatest during the breeding season. Nonetheless, physiological and behavioral differences between ARTs can manifest throughout the year, possibly involving costs that may contribute to maintain ARTs within populations. Using the number of nematode larvae per gram of feces (LPG) as a proxy, we explored the temporal changes in lung parasite infection in territorial and nonterritorial male chamois Rupicapra in the Gran Paradiso National Park (Italy), between 2011 and 2012. We aimed to identify which tactic‐specific physiological and behavioral features (including age, hormonal levels, inter‐ and intrasexual interactions, and space use) or climatic factors (temperature and precipitation) best explained yearly variation in parasite infection within and between ARTs. Generalized additive mixed models showed that the fecal larval counts of lung nematodes underwent strong temporal changes in both male types. Differences between ARTs (with higher LPG values in territorial than nonterritorial males) were greatest during the rut and—to a lesser extent—in spring, respectively, at the peak and at the onset of territoriality. The difference in LPG between tactics was largely explained by the greater levels of hormone metabolites in territorial males during the rut. The other variables did not contribute significantly to explain the different shedding of larvae within and between ARTs. Our analysis suggests that different values of LPG between territorial and nonterritorial males are largely a result of tactic‐specific differences in the secretion of hormone metabolites, but only during the rut. To clarify whether rut‐related parasitism contributes to the maintenance of ARTs, tactic‐specific life history trade‐offs, for example, between reproduction and parasite‐related mortality, must be investigated.

Linking alternative reproductive tactics and habitat selection in Northern chamois

“…Furthermore, our classification proved effective at capturing major variations in several chamois traits; for example, T and NT showed significant differences in altitudinal range (Corlatti et al, 2020;Corlatti, Bassano, et al, 2013), stress physiology (Corlatti, 2018;Corlatti et al, 2012, testosterone levels (Corlatti et al, 2012(Corlatti et al, , 2019, parasite burden (Corlatti et al, 2012(Corlatti et al, , 2019, foraging behavior (Corlatti & Bassano, 2014;Corlatti, Bassano, et al, 2013), rutting behavior (Corlatti, Caroli, et al, 2013), mating success (Corlatti et al, 2012), and reproductive success (Corlatti, Bassano, et al, 2015). (Tarquini et al, 2007(Tarquini et al, , 2012 covering the entire study area.…”

“…Details of the statistical procedure for the distinction between ARTs are reported in Corlatti et al (2012), while full data and codes are available from Corlatti et al (2019). It is important to stress that, although this dichotomic classification is unlikely to fully capture interindividual variability (e.g., owing to variation in home-range size and behavioral patterns displayed by males, cf.…”

“…It is important to stress that, although this dichotomic classification is unlikely to fully capture interindividual variability (e.g., owing to variation in home-range size and behavioral patterns displayed by males, cf. Corlatti et al, 2012;Corlatti et al, 2019), the occurrence of territorial and nonterritorial behavior has been long recognized in chamois (cf. Krämer, 1969) and in several other ungulates (Maher & Lott, 1995;Owen-Smith, 1977).…”

“…During the November rut, territorial males actively defend an exclusive area at relatively low elevations (Corlatti et al, 2012;Krämer, 1969;von Hardenberg et al, 2000), while nonterritorial males display following behavior and territory intrusions (Corlatti et al, 2012;Krämer, 1969;von Hardenberg et al, 2000). ARTs profoundly differ in several ecological and physiological aspects during the rut (Corlatti & Bassano, 2014;Corlatti, Bassano, et al, 2013;Corlatti et al, 2012Corlatti et al, , 2019. In the rest of the year, on the other hand, such differences are milder (cf.…”

“…In the rest of the year, on the other hand, such differences are milder (cf. Corlatti et al, 2019). Information on space use in territorial and nonterritorial male chamois is limited: Lovari et al (2006) investigated alternative strategies of space use, supporting the occurrence of resident and migrant males, which may partly associate with ARTs.…”