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Refuge sharing network predicts ectoparasite load in a lizard.

Leu ST, Kappeler PM, Bull CM - Behav. Ecol. Sociobiol. (Print) (2010)

Bottom Line: Highly connected lizards that frequently used their neighbors' refuges were characterized by higher tick loads.Furthermore, lizards that used many different refuges had lower cross- and self-infection risks and lower tick loads than individuals that used relatively fewer refuges.Our study provides important empirical data to further understand how indirectly transmitted parasites move through host populations and influence individual parasite loads.

View Article: PubMed Central - PubMed

ABSTRACT
Living in social groups facilitates cross-infection by parasites. However, empirical studies on indirect transmission within wildlife populations are scarce. We investigated whether asynchronous overnight refuge sharing among neighboring sleepy lizards, Tiliqua rugosa, facilitates indirect transmission of its ectoparasitic tick, Amblyomma limbatum. We fitted 18 neighboring lizards with GPS recorders, observed their overnight refuge use each night over 3 months, and counted their ticks every fortnight. We constructed a transmission network to estimate the cross-infection risk based on asynchronous refuge sharing frequencies among all lizards and the life history traits of the tick. Although self-infection was possible, the network provided a powerful predictor of measured tick loads. Highly connected lizards that frequently used their neighbors' refuges were characterized by higher tick loads. Thus, indirect contact had a major influence on transmission pathways and parasite loads. Furthermore, lizards that used many different refuges had lower cross- and self-infection risks and lower tick loads than individuals that used relatively fewer refuges. Increasing the number of refuges used by a lizard may be an important defense mechanism against ectoparasite transmission in this species. Our study provides important empirical data to further understand how indirectly transmitted parasites move through host populations and influence individual parasite loads.

No MeSH data available.


Related in: MedlinePlus

Spearman rank correlation between number of refuges used (divided by the number of days monitored) and median tick load. Line of best fit is shown for illustration
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Fig6: Spearman rank correlation between number of refuges used (divided by the number of days monitored) and median tick load. Line of best fit is shown for illustration

Mentions: From the transmission network of the study population (Fig. 1) and correlation analyses of network parameters and infection risks (Table 1), we found that node in-strength (divided by the number of days monitored) was positively correlated with median tick load (Fig. 2). Thus, lizards that were exposed to high cross-infection risk also had high tick loads. Similarly, self-infection risk (divided by the number of days monitored) and median tick load were positively correlated (Fig. 3). Comparison of the cross- and self-infection risk showed no significant difference in their strength (paired t-test: t17 = 1.64, Monte Carlo P = 0.068). Finally, the number of different refuges used was negatively correlated with node in-strength (both divided by the number of days monitored) (Fig. 4). Thus, lizards that used more refuges experienced a lower cross-infection risk. Similarly, the number of different refuges used was negatively correlated with self-infection risk (both divided by the number of days monitored) (Fig. 5). These reduced infection risks translated into a negative correlation between the number of different refuges used (divided by the number of days monitored) and median tick load (Fig. 6).Fig. 1


Refuge sharing network predicts ectoparasite load in a lizard.

Leu ST, Kappeler PM, Bull CM - Behav. Ecol. Sociobiol. (Print) (2010)

Spearman rank correlation between number of refuges used (divided by the number of days monitored) and median tick load. Line of best fit is shown for illustration
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2926892&req=5

Fig6: Spearman rank correlation between number of refuges used (divided by the number of days monitored) and median tick load. Line of best fit is shown for illustration
Mentions: From the transmission network of the study population (Fig. 1) and correlation analyses of network parameters and infection risks (Table 1), we found that node in-strength (divided by the number of days monitored) was positively correlated with median tick load (Fig. 2). Thus, lizards that were exposed to high cross-infection risk also had high tick loads. Similarly, self-infection risk (divided by the number of days monitored) and median tick load were positively correlated (Fig. 3). Comparison of the cross- and self-infection risk showed no significant difference in their strength (paired t-test: t17 = 1.64, Monte Carlo P = 0.068). Finally, the number of different refuges used was negatively correlated with node in-strength (both divided by the number of days monitored) (Fig. 4). Thus, lizards that used more refuges experienced a lower cross-infection risk. Similarly, the number of different refuges used was negatively correlated with self-infection risk (both divided by the number of days monitored) (Fig. 5). These reduced infection risks translated into a negative correlation between the number of different refuges used (divided by the number of days monitored) and median tick load (Fig. 6).Fig. 1

Bottom Line: Highly connected lizards that frequently used their neighbors' refuges were characterized by higher tick loads.Furthermore, lizards that used many different refuges had lower cross- and self-infection risks and lower tick loads than individuals that used relatively fewer refuges.Our study provides important empirical data to further understand how indirectly transmitted parasites move through host populations and influence individual parasite loads.

View Article: PubMed Central - PubMed

ABSTRACT
Living in social groups facilitates cross-infection by parasites. However, empirical studies on indirect transmission within wildlife populations are scarce. We investigated whether asynchronous overnight refuge sharing among neighboring sleepy lizards, Tiliqua rugosa, facilitates indirect transmission of its ectoparasitic tick, Amblyomma limbatum. We fitted 18 neighboring lizards with GPS recorders, observed their overnight refuge use each night over 3 months, and counted their ticks every fortnight. We constructed a transmission network to estimate the cross-infection risk based on asynchronous refuge sharing frequencies among all lizards and the life history traits of the tick. Although self-infection was possible, the network provided a powerful predictor of measured tick loads. Highly connected lizards that frequently used their neighbors' refuges were characterized by higher tick loads. Thus, indirect contact had a major influence on transmission pathways and parasite loads. Furthermore, lizards that used many different refuges had lower cross- and self-infection risks and lower tick loads than individuals that used relatively fewer refuges. Increasing the number of refuges used by a lizard may be an important defense mechanism against ectoparasite transmission in this species. Our study provides important empirical data to further understand how indirectly transmitted parasites move through host populations and influence individual parasite loads.

No MeSH data available.


Related in: MedlinePlus