Influences of Maternal Corticosterone and Selection for Contrasting Adrenocortical Responsiveness in Japanese Quail on Developmental Instability of Female Progeny

Abstract

Differences in developmental instability were assessed in female offspring of Japanese quail hens selected for reduced (low stress, LS) or exaggerated (high stress, HS) plasma corticosterone (B) response to stress and treated with a placebo or B during egg formation. Hens of each line were implanted (s.c.) with either a silastic tube containing no B (controls) or one filled with B. Female chicks hatched from each of the 4 line x implant treatment combinations were retained for examination of 3 bilateral traits at 130 d of age: length of the tibiotarsus, middle toe length, and distance between the auditory canal and the nares (face length, FL). Greater bilateral trait size variances were associated with measurement of tibiotarsus length (P < 0.04) and middle toe length (P < 0.06) in the HS line, supporting our previous findings in the opposite sex that developmental instability (i.e., fluctuating asymmetry, FA) of certain morphological traits is more pronounced in HS than LS adult quail. The HS quail are also known to exhibit greater adrenocortical responsiveness to a wide range of stressors, and they are more easily frightened than LS birds. Therefore, the line differences in FA (HS > LS) found previously in males and herein in females may simply reflect the differential responsiveness of the birds to chronic social and physical environmental stressors. In addition, the present study detected more (albeit marginally so, P < 0.06) bilateral variability (i.e., heightened FA) in FL of quail hatched from mothers treated with B, a finding entirely due to the very high FL variance observed in the female offspring of B-treated HS hens. Because others have found in ovo B treatment to be associated with heightened FA in chick tarsus bone length and because we have also demonstrated that greater yolk B deposition occurs in eggs from both unstressed and stressed HS quail hens than their LS counterparts, the present maternal B treatment may be acting independently, or in combination with HS genomic effects, to adversely affect developmental stability.

Maternal Stress Affects Fetal Growth but Not Developmental Instability in Rabbits

“…These results therefore indicate that at least in this rabbit model and for the compound applied, maternal stress does not result in elevated DI levels of offspring. This is an unexpected result because earlier studies that induced maternal stress through corticosterone or cortisol treatment in several bird and fish species, did find evidence for an increase in offspring DI [23][24][25]. In this study, the pregnant does responded to the treatment by feeding less and they gained less weight, which led to a reduction in pup weight and ossification.…”

“…Secondly, previous studies on the effects of maternal glucocorticoids have used birds and fish as a model system [22][23][24][25], which are oviparous animals. In contrast, here we studied maternal stress in a mammal.…”

“…For example, FA increased in juveniles of Atlantic salmon after experimental maternal cortisol enhancement where the highest level of FA was observed in offspring that had been challenged with both high prenatal cortisol levels and hyperthermia [22]. Similarly, corticosterone or cortisol treatment, either through the mother or directly into the egg, has resulted in increased FA in hatchlings in chickens, Japanese quails and damselfish [23][24][25]. In a free-living species, high corticosterone levels were related to elevated FA levels of male nestlings in tree creepers [26].…”

Fluctuating Asymmetry and Steroid Hormones: A Review

“…The results were further corroborated by two studies that investigated two divergent genetic lines of Japanese quail selected for their high (HS) and low stress (LS) plasma corticosterone response to acute restraint stress. It was found that HS quail had significantly greater FA in the lengths of tibiotarsus and metatarsus bones, middle toe, and faces than LS quail [56,60].…”

“…The resulting experiments involved prenatal exposure to corticosterone and concomitant changes in body symmetry in birds. It was found that corticosterone treatment resulted in greater embryonic mortality, reduced growth, and increased FA in tarsus length in chickens and marginally elevated FA of the face length in Japanese quails [55,56]. A separate experiment manipulated cortisol concentrations in embryos of coral reef damselfish and explored the adverse effects on growth and survival.…”