Infection with an amphibian pathogenic fungus: is there an altitudinal trend? ZOOL-502 UBC November Angie Nicolás

1980's: decline in amphibian populations 122 spp gone extinct in the past 30 years 1/3 of amphibian populations are threatened (Stuart et al 2004) Causes involved: Habitat loss Pollution Increased UV radiation Disease In Central and South America 37% of the 113 spp of Atelopus have declined in the past 20 years (La Marca et al, 2005) Amphibian population declines

Batrachochytrium dendrobatidis Phylum Chytridiomycota, Class Chytridiomycetes, Order Chytridiales (Longcore y col., 1999)

(Marantelli et al 2004)

Optimum growth 17-25°C 50% cultures dies after 48h at 30°C (Longcore et al, 1999) Experimentally infected frogs exposed to high temperatures are able to eliminate the pathogen (Woodhams et al, 2003) Interspecific variation in the response to the pathogen (Blaustein et al, 2005; Woodhams et al, 2006) Lowland frogs are infected less frequently than highland frogs Prevalence increases in cool months (Berger et al, 2004) Outbreaks are associated with hot and dry years (Pounds, 1999) B. dendrobatidis and temperature

What happens if we consider only one species? Will prevalence increase with altitude? Can variations in temperature explain the tendency?

Hypothesis: Prevalence with Bd infection will be higher in populations of Mannophryne herminae outside of B. dendrobatidis optimum thermic range.

Study area: Henri Pittier National Park. Estado Aragua, Venezuela Map credit: Dinora Sánchez

Cata 90 m La Trilla 115 m Hidrocentro 375 m El Salto 600 m Riítos de Pittier 840 m Virgen 950 m Rancho Grande 1158 m Guacamaya 890 m Guamita 762 m Profauna 552 m Altitudinal distribution of sampling sites Southern Slope Northern Slope

1- Manually collected toads in each site (n=21±4) 2- Sexed and measured (SVL) 3-Toe clipped and stored tissue samples in 70%ethanol. Recorded air temperature (every hour) for 9 weeks In the field In the lab 1-DNA extraction and amplification (qPCR) following Boyle et al Ran samples (duplicates) -0.1, 1, 10 and 100 zoosp. eq. Standards -Positive and negative controls 2-Zoosp.eq. >0.1 = Positive sample 3- Calculate parasitic load Methodology

ANCOVA Temperature in both slopes RESULTS

Mean temperature analysis

Maximum temperatures analysis

Linear regressions of N° hours with Temp> 25°C and 29°C 790 m 910 m

Prevalences per sampling site Atelopus Mean prevalence= 13 ± 5% 27/209 frogs infected

VariableCVglProb, χ2 Mes ,09432 Media0,61310,43357 Máx, ,15362 Prom> ,02023 Prom>= ,05112

VARIABLE LIKELIHOOD RATIO LOWER CIHIGHER CI ALTITUDE1,0010,9991,002 SVL0,170,0650,443 Logistic regression analysis

QUESTIONS Acknowledgments Fundación La Salle de Ciencias Naturales Estación Biológica Rancho Grande Margarita Lampo Dinora Sánchez Francisco Nava Javier Valera César Herrera Juan José Cruz