Mating pattern variability among western toad (Bufo boreas) populations

Abstract

Breeding ecology and mating patterns of the western toad, Bufo boreas, were examined in three large explosively breeding populations in the Oregon Cascade Mountains. Two mating patterns occurred variably within and among the three populations. First, a large male mating advantage was observed in two of the three populations when data from all the days of data collection were combined. When each day of breeding was analyzed separately, there was a large male mating advantage on 3 of 5 days at one population, and mating was random on all days at the two other populations. The second mating pattern, positive assortative mating by size, was observed at two of the three populations. This pattern was found on separate days of breeding as well as when data from all days were combined at one population, and on only one day of breeding at the second population.In a survey of anuran amphibian mating patterns, intraspecific variation was found in 13 of 15 species, including the present study of the western toad. Intrapopulation variation in mating patterns among breeding years has been observed in 5 of 8 anurans, whereas within-site, within-year mating pattern variation has only been reported for the western toad. These results strongly suggest that anuran mating patterns are frequently neither species-specific nor population-specific attributes. Variable mating patterns were most commonly observed in explosively-breeding anurans. Explosive breeders may be susceptible to variable mating patterns because they may be more sensitive to fluctuations in environmental conditions, demographic parameters, and the intensities of intrasexual competition and mate choice.

Breeding behavior and mating system in relation to body size in Rana chensinensis, a temperate frog endemic to northern China

“…On the other hand, if females are widely dispersed and available over a long period, mate searching and guarding will be more effective in reaching mating success, and in this situation mate choice can occur (Wells 1977a, b). Some studies found that non-random mating in terms of a sizeassortative pattern varies extensively from population to population (see Olson et al 1986 for review). Therefore, the relative importance of various contributing mechanisms to the variation in mating system remains a major question in need of study (Crespi 1989;Arnqvist et al 1996).…”

Breeding Activity of the Neotropical Treefrog Hyla elegans (Anura, Hylidae)

“…The two mechanisms of sexual selection proposed by Darwin (1871), male-male competition and female choice, are involved in the genesis of nonrandom mating patterns (Olson et al, 1986). In anurans, the intensity of each mechanism of sexual selection depends, in part, on the duration of breeding period (Wells, 1977;Ryan, 1985).…”

Mating patterns of Rana kukunoris from three populations along an altitudinal gradient on the Tibetan Plateau

“…However, it does highlight the need for multi-site or multi-year studies to proYide an accurate behaYioral or ecological profile of the system (Olson et al, 1986). Future studies aimed to understand the role of sexual selection in mating patterns, especially female choice, should be designed to make observations throughout breeding seasons and across breeding seasons within species.…”

“…Among anurans, considerable variation in mating pattern can be found in different populations of the same species (Gittins et al, 1980;Höglund and Robertson, 1987;Briggs, 2008), or even within different breeding seasons in the same population (Olson et al, 1986;Morris, 1989;Wagner and Sullivan, 1995). Some of this mating pattern variation has been explained by the length of the breeding season (Wells, 1977, reviewed by Sullivan et al, 1995, the population density and operational sex ratio (OSR: the ratio calculated from the number of males to the number of fertilizable females; Lüddecke, 2001) at different times and in different populations (Elmberg, 1991).…”