Forms and prevalence of intersexuality and effects of environmental contaminants on sexuality in cricket frogs (Acris crepitans).

Abstract

Cricket frogs (Acris crepitans) from several different sites in Illinois were collected to assess the effects of environmental contamination on the prevalence of intersex gonads. Of 341 frogs collected in 1993, 1994, and 1995, 2.7% were intersex individuals. There was no statistically significant relationship between the chemical compounds detected and cricket frog intersexuality. However, there was an association approaching significance (p = 0.07) between the detection of atrazine and intersex individuals. A comparison of reference sites with sites that had point polychlorinated biphenyl (PCB) and polychlorinated dibenzofuran (PCDF) contamination revealed a significant relationship between sex-ratio reversal and contamination with PCBs and PCDFs. The sex ratio of juvenile frogs studied from three sites with PCB and PCDF point contamination favored males over females, which was the opposite of the sex ratio in control ponds (p = 0.0007). The statistically significant correlation between organochlorine contamination and sex-ratio reversal suggests PCBs and PCDFs can influence cricket frog sexual differentiation. The current study suggests that in cricket frogs, sex ratios and the prevalence of intersex gonads are altered by environmental contamination.ImagesFigure 1Figure 2

Gonadal Differentiation and Development in the Snouted Treefrog,Scinax fuscovarius(Amphibia, Anura, Hylidae)

“…These cases, even with a low frequency, represent interesting documented cases of malformations in tadpoles living in natural conditions, because most malformations described in the literature have been in juveniles and adults from experimental treatments (Reeder et al, 1998;Hayes et al, 2002Hayes et al, , 2003Carr et al, 2003;Coady et al, 2004;Jooste et al, 2005;Skelly et al, 2010;Papoulias et al, 2013;Goldberg, 2013).…”

Disrupted Oogenesis in the Frog Xenopus tropicalis after Exposure to Environmental Progestin Concentrations1

“…Reproductive disorders, including increased incidences of intersex gonads and impaired oocyte development, have been reported in wild aquatic organisms at contaminated sites throughout the world [1][2][3][4][5][6][7][8]. The research into potential causes for these reproductive disorders has mainly focused on environmental chemicals interfering with estrogen or androgen signaling.…”

Assessing the physiological sensitivity of amphibians to extreme environmental change using the stress endocrine responses

“…However, adult frogs and toads may also absorb substances through the skin and develop gonadal dysfunction even in terrestrial habitats. In several populations of cricket frogs (Acris crepitans) studied across field sites in Illinois (USA), for example, a striking relation between the prevalence of intersexuality and the scope of environmental contamination with atrazine, polychlorinated biphenyl, and polychlorinated dibenzofuran has been observed (Reeder et al 1998). On a related topic, male frogs of L. pipiens exposed to a pharmaceutical compound, diethylstilbestrol, synthesize and secrete vitellogenin (Selcer and Verbanic 2014), a major precursor to the egg-yolk proteins of oviparous vertebrates.…”