Premium
Sexual maturity, seasonal estrus, and gestation in female Indo‐Pacific bottlenose dolphins Tursiops aduncus inferred from serum reproductive hormones
Author(s) -
ZHANG Peijun,
WEI Zhengzhi,
HUI SukWai,
ABEL Grant,
MARTELLI Paolo,
HAO Yujiang,
LI Songhai
Publication year - 2021
Publication title -
integrative zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.904
H-Index - 34
ISSN - 1749-4877
DOI - 10.1111/1749-4877.12491
Subject(s) - biology , testosterone (patch) , sexual maturity , bottlenose dolphin , endocrinology , gestation , medicine , pregnancy , hormone , andrology , ecology , genetics
Reproductive hormones in serum concentrations of progesterone, estradiol, and testosterone in female Indo‐Pacific bottlenose dolphins ( Tursiops aduncus , n = 12) housed in Ocean Park Hong Kong were investigated in the present study. Results showed that, onset of puberty of captive Indo‐Pacific bottlenose dolphins was at 5 years while sexual maturity was at 6. Average serum progesterone concentrations in non‐pregnant sexually mature individuals was 0.33 (0.25–0.97) ng/mL (interquartile), significantly higher than in immature ones 0.26 (0.25–0.38) ng/mL. This study found significant difference in serum estradiol concentrations between individuals at the onset of puberty (9.5 ± 1.7 pg/mL, ±SD) and not (below detection limit 9 pg/mL). A slightly seasonal breeding pattern, with progesterone values tend to be higher from February to October (0.38 [0.25–1.07] ng/mL) was inferred. During pregnancy, serum progesterone concentrations range from 10.54 ± 8.74 ng/mL (indexed month post‐conception [IMPC] 0) to 25.49 ± 12.06 ng/mL (IMPC 2), and display a bimodal pattern with 2 peaks in early‐ (25.49 ± 12.06 ng/mL, IMPC 2) and late‐pregnancy (21.71 ± 10.25 ng/mL, IMPC 12), respectively. Serum estradiol concentrations can seldom be detected in early‐pregnancy and increase constantly in mid‐ (9.45 ± 1.83 pg/mL) and late‐pregnancy (11.88 ± 3.81 pg/mL), with a spike (15.45 ± 6.78 pg/mL) 1 month prior to delivery. Serum testosterone concentrations elevate significantly in IMPC 7 (0.36 ± 0.10 ng/mL) compared to other months (0.16 ± 0.10 ng/mL) of the year. The present study provides normal concentration profiles for some reproductive hormones in female Indo‐Pacific bottlenose dolphins and can contribute to the breeding monitoring of this species. Also, our study would shed further light on the reproductive physiology of small cetaceans.