Visible Implant Elastomer as a Viable Marking Technique for Common Mistfrogs (Litoria rheocola)

Artificial Visible Implant Elastomer (VIE) tags of different colour and symmetry do not influence mate choice in a cichlid

Experimental individuals are frequently marked with coloured tags for individual identification. Except for birds, the consequences of such artificial tagging on mate choice have been rarely investigated even though individuals often prefer naturally brightly coloured or symmetrically ornamented mates. We tested whether differently coloured Visible Implant Elastomer (VIE) tags influence female mate choice in rainbow kribs,Pelvicachromis pulcher. Females were allowed to simultaneously choose between a control and a VIE-marked male. The VIE-marked male carried two tags of the same colour (red, blue, green or white) set symmetrically or asymmetrically. Females did not show a preference for or avoidance of males carrying any of the colours compared to control males, no matter if the tags had been set symmetrically or asymmetrically. Although we found no discrimination for or against colour-tags, we highlight the importance of considering potential influences of colour-marks on mate choice in behavioural and evolutionary studies.

Infection dynamics in frog populations with different histories of decline caused by a deadly disease

Pathogens can drive host population dynamics. Chytridiomycosis is a fungal disease of amphibians that is caused by the fungus Batrachochytrium dendrobatidis (Bd). This pathogen has caused declines and extinctions in some host species whereas other host species coexist with Bd without suffering declines. In the early 1990s, Bd extirpated populations of the endangered common mistfrog, Litoria rheocola, at high-elevation sites, while populations of the species persisted at low-elevation sites. Today, populations have reappeared at many high-elevation sites where they presently co-exist with the fungus. We conducted a capture-mark-recapture (CMR) study of six populations of L. rheocola over 1 year, at high and low elevations. We used multistate CMR models to determine which factors (Bd infection status, site type, and season) influenced rates of frog survival, recapture, infection, and recovery from infection. We observed Bd-induced mortality of individual frogs, but did not find any significant effect of Bd infection on the survival rate of L. rheocola at the population level. Survival and recapture rates depended on site type and season. Infection rate was highest in winter when temperatures were favourable for pathogen growth, and differed among site types. The recovery rate was high (75.7-85.8%) across seasons, and did not differ among site types. The coexistence of L. rheocola with Bd suggests that (1) frog populations are becoming resistant to the fungus, (2) Bd may have evolved lower virulence, or (3) current environmental conditions may be inhibiting outbreaks of the fatal disease.