The use of genetic markers to reveal dynamic processes in a common toad (Bufo Bufo) population

Coles, RS

Abstract

In contrast to birds and mammals for example, amphibian population studies only rarely capture information based on genealogical relationships among individuals. As a consequence, we only have very limited knowledge about individual fitness measures such as lifetime reproductive success and the consequences of such variation on the linkage between generations of amphibians in the wild. The present thesis makes use of an existing long-term study on the common toad (Bufo bufo) in southern England (Dorset) to genetically identify parent-offspring relationships among approximately 850 individual toads, representing two successive generations (2004/2005/2006 and 2008/2009). The dataset enabled the comparison of measures of effective population size as well as effective breeding size, revealing ratios between 0.07 and 0.26. These data also showed an increasing trend with time and were (by some estimators) confirmed by the cross-generational parentage analysis which revealed a high reproductive skew among individuals. Forty-five percent of offspring could be assigned to a least one parent; in total, 6% of male parents and 30% of female parents were inferred. The pedigree information was also used to identify a possible hereditary basis for an observed decrease in female body condition and fecundity correlated to increased environmental temperatures. There was no indication for heritability of body size, body weight and body condition, suggesting that the documented decrease is based on phenotypic plasticity rather than evolutionary adaptation. However, kinship data that shows the population is less inbred with time coupled with the effective breeding number estimates showing an increasing trend with time suggest that despite the absence of evolutionary change, this population may still be able to circumvent the adverse effects associated with decreased body condition.

Citation

Coles, R. The use of genetic markers to reveal dynamic processes in a common toad (Bufo Bufo) population. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Nov 8, 2013
• Publicly Available Date: Nov 8, 2013
• Award Date: Sep 2, 2013