Uncovering the Sex-Specific Endocrine Responses to Reproduction and Parental Care

Abstract

Hormones mediate physiological and behavioral changes in adults as they transition into reproduction. In this study, we characterize the circulating levels of five key hormones involved in reproduction in rock doves (Columba livia): corticosterone, progesterone, estradiol, testosterone, and prolactin using univariate and multivariate approaches. We show similar patterns as previous studies in the overall patterns in circulating levels of these hormones, i.e., testosterone (males) and estradiol (females) high during nest-building or egg-laying, prolactin increasing at mid-incubation and peaking at hatching (both sexes), and elevated corticosterone levels in later incubation and early nestling development. In our investigation of hormone co-variation, we find a strong correlation between prolactin and corticosterone across sampling stages and similarities in earlier (early to mid-incubation) compared to later (late incubation to nestling d9) sampling stages in males and females. Finally, we utilized experimental manipulations to simulate nest loss or altered caregiving lengths to test whether external cues, internal timing, or a combination of these factors contributed most to hormone variation. Following nest loss, we found that both males and females responded to the external cue. Males generally responded quickly following nest loss by increasing circulating testosterone, but this response was muted when nest loss occurred early in reproduction. Similar treatment type, e.g., removal of eggs, clustered similarly in hormone space. These results suggest internal drivers limited male response early in reproduction to nest loss. In contrast, circulating levels of these hormones in females either did not change or decreased following nest manipulation suggesting responsiveness to external drivers, but unlike males, this result suggests that reproductive processes were decreasing.

Characteristics of glucolipid metabolism and oxidative stress in breeding pigeons (Columba livia) during lactation

“…During the poultry breeding season, reproductive hormones that are important for parental behaviour and initiation of egg production include LH and FSH, which are released by the anterior pituitary, and testosterone, estradiol (E2), and progesterone produced by the ovaries (Buntin, 1996; Ramakrishnan et al, 2007). Consistent with previous studies, in middle and late lactation—with the maturation of follicle development—the plasma E2 and progesterone levels in female pigeons gradually increased (Austin et al, 2021; Dong et al, 2013; Xie et al, 2019). Levels of LH and FSH produced by the pituitary and testosterone secreted by the ovary gradually decreased in middle and late lactation.…”

Androgen-armoured amazons: reversed sex roles in coucals are associated with testosterone in females but not males

“…Slightly elevated levels of progesterone during this period are consistent with findings from other bird species during egg-laying (e.g. [93,103]). It is therefore rather surprising that, in white-browed coucals, progesterone levels tended to be higher during the pre-breeding period than during the mating period.…”

“…It is therefore rather surprising that, in white-browed coucals, progesterone levels tended to be higher during the pre-breeding period than during the mating period. Low levels of progesterone in the incubation phase of male black coucals are consistent with low-progesterone concentrations of incubating females of other species [93,103,104]. However, the hormonal regulation of incubation behaviour requires a suite of interacting hormones [104] and further studies including measurements and experimental manipulations of sex steroids and prolactin in males would be required to elucidate the hormonal regulation of incubation behaviour in male coucals.…”

Spatio-temporal transcriptome dynamics coordinate rapid transition of core crop functions in ‘lactating’ pigeon

“…Taken together, these results indicated that the crop of parent pigeons undergoes dramatic changes in morphology during the breeding stages, in which each sex shows varying degrees of change, accompanied by a transition in parental behavior. This reflects a change in the division of labor between sexes during the breeding stages which may be related to shifts in gonadal steroid hormone levels [ 11 , 12 ]. For example, in female pigeons, serum estradiol concentration increases dramatically in the later stages of feeding [ 13 ], possibly to prepare for the next breeding stages.…”