Integrative demographic study of the Iberian painted frog (Discoglossus galganoi): inter‐annual variation in the effective to census population size ratio, with insights on mating system and breeding success

Abstract

In the face of worldwide amphibian declines, integrative studies combining individual-based information and genetic data represent a powerful approach to produce robust, reliable, and comparable assessments of demographic dynamics. The Iberian painted frog (Discoglossus galganoi) is endemic to Spain and Portugal and shows decreasing population trends across its range, but few studies have attempted to estimate census sizes or assess genetic diversity in wild populations, and little is known about their reproductive biology. We applied an integrative approach based on the combination of capture-mark-recapture data and multilocus genotypes to monitor a breeding population of D. galganoi in central Spain during two consecutive breeding seasons, focusing on the estimation of demographic parameters and their temporal variation. Specifically, we estimated the number of adults (N a), the effective population size (N e), and the effective number of breeders (N b), as well as survival and migration rates. We documented a >50% decrease in the estimated number of adults of both sexes between the breeding seasons of 2018 and 2019, probably associated with reduced rainfall in the latter. Estimates of N b and the N b /N a ratio were low in both seasons, with a 20-30% decrease in N b and a 47% increase in the N b /N a ratio in 2019. Based on the reconstruction of pedigrees from larval and adult genotypes, we provide the first genetic evidence of polygamy in males and females of D. galganoi and the first estimates of breeding success in the species.

Geographical Variation in Body Size and the Bergmann’s Rule in Andrew’s Toad (Bufo andrewsi)

“…Like those of most other ectotherms [ 67 , 105 , 106 ], anuran life-history traits (e.g., age at sexual maturity, mean age, and longevity) vary with environmental conditions [ 66 , 82 , 107 , 108 ]. For instance, populations experiencing longer growth seasons have younger ages at sexual maturity, mean age, and longevity than populations experiencing shorter growth seasons in previous studies that discussed geographical variation in B. andrewsi age structure [ 22 , 45 ].…”

“…For instance, individuals living in harsh environments devote more time and energy to growing, which causes them to become older and to grow larger, and, thus, these individuals are of a larger body size [ 62 ]. Furthermore, some species display sex-specific relationships between environmental factors and body size because males and females suffer distinct selection pressures in the same environment [ 63 , 64 , 65 , 66 , 67 ]. As such, the extent to which these hypotheses explain the ecogeographic patterns of body size variation remains uncertain.…”

“…The anuran is an ideal model for exploring the influence of environmental changes on body size, since their highly permeable skin, unshelled eggs, low vagility, and frequent territoriality are particularly vulnerable to environmental stresses (e.g., temperature, precipitation, and ultraviolet radiation) [ 68 ]. However, few studies exploring body size variation have been conducted, of which only nearly 5% of all amphibian species have been studied, and there is much controversy as to whether the effects of environmental changes on body size variation support Bergmann’s rule [ 45 , 55 , 57 , 61 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 ]. Although the effect of temperature on body size is contested, precipitation, as a proxy for productivity, has been found to affect the body size of frogs [ 24 , 83 ].…”

Testis Size Variation and Its Environmental Correlates in Andrew’s Toad (Bufo andrewsi)

“…Life-history theory predicts that trade-offs between current reproductive investments and future reproductive success and/or survival enable an organism to cope with environmental changes [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. This inevitable trade-off is reflected by testis size, a dominant measure of reproductive investment in males, varying extensively within and between species [ 8 , 9 , 10 , 11 ]. Much of the interspecific variation in testis size has been attributed to differences in sexual selection pressures [ 10 , 12 , 13 , 14 ].…”