Female polyandry under male harassment: the case of the
common toad (Bufo bufo)

Sztatecsny, M; Jehle, R; Burke, T; Hodl, W

Abstract

Several recent studies have demonstrated the occurrence of multiple paternity in
anuran amphibians, implying that it is more common than previously thought.
However, an adaptive explanation for polyandry in anurans is still lacking. The
common toad Bufo bufo is an explosively breeding species that releases its eggs in
strings. The operational sex ratio (OSR) is male biased, causing strong scramble
competition among males; females can even drown through harassment during
multiple amplexi. We used microsatellite markers to determine patterns of
paternity in natural B. bufo populations and experimentally mated individuals
(females exposed to either two or six males). Thirty per cent of field-collected and
22% of experimentally produced egg strings were sired by at least two males; all
others were sired by a single father. Multiple paternities arose only from multiple
amplexi, and we found no indication of fertilization from non-amplexing males,
for example through free-swimming sperm. Our results suggest that polyandry in
B. bufo is likely to occur most often at high population densities, and under the
most male-biased OSRs. Moreover, polyandry might be interpreted as being the
consequence of females spawning when amplexed by a few males, to avoid the risk
of drowning by amplexus with multiple males.

Citation

common toad (Bufo bufo). Journal of Zoology, 270, 517-522. https://doi.org/10.1111/j.1469-7998.2006.00120.x

• Journal Article Type: Article
• Publication Date: Jan 1, 2006
• Deposit Date: Oct 30, 2009
• Journal: Journal of Zoology
• Print ISSN: 0952-8369
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 270
• Pages: 517-522
• DOI: https://doi.org/10.1111/j.1469-7998.2006.00120.x
• Keywords: anura; Bufo bufo; microsatellites; multiple; paternity; sex ratio; sexual conflict
• Publisher URL: http://dx.doi.org/10.1111/j.1469-7998.2006.00120.x