TY - JOUR
T1 - Seasonal change in male reproductive investment of a fish
AU - Fujimoto, Shingo
AU - Takeda, Satoshi
AU - Yagi, Mitsuharu
AU - Yamahira, Kazunori
N1 - Funding Information:
We would like to thank M. Okada, and K. Saito for fish collection. This study was supported by the Sasakawa Scientific Research Grant from The Japan Science Society (28-521) and the Spatiotemporal Genomics Project promoted by the University of the Ryukyus to S.F, and by JSPS KAKENHI Grants to S.F. (13 J04092, 19 K16232), and K.Y. (20570019), from the Japanese Ministry of Education, Culture, Sports, Science and Technology. We thank Harry Taylor, PhD, from Edanz Group ( https://en-author-services.edanzgroup.com/ac ) for editing a draft of this manuscript.
Funding Information:
We would like to thank M. Okada, and K. Saito for fish collection. This study was supported by the Sasakawa Scientific Research Grant from The Japan Science Society (28-521) and the Spatiotemporal Genomics Project promoted by the University of the Ryukyus to S.F, and by JSPS KAKENHI Grants to S.F. (13?J04092, 19?K16232), and K.Y. (20570019), from the Japanese Ministry of Education, Culture, Sports, Science and Technology. We thank Harry Taylor, PhD, from Edanz Group (https://en-author-services.edanzgroup.com/ac) for editing a draft of this manuscript. R scripts used for statistical analysis are available from the Dryad Digital Repository (https://doi.org/10.5061/dryad.dv41ns1vj).
Funding Information:
This study was partially supported by the Sasakawa Scientific Research Grant from The Japan Science Society (28–521) and the Spatiotemporal Genomics Project promoted by the University of the Ryukyus to S. F., and by JSPS KAKENHI Grants from the Japanese Ministry of Education, Culture, Sports, Science and Technology to S. F. (13 J04092, 19 K16232), and to K. Y. (20570019).
Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer Nature B.V. part of Springer Nature.
PY - 2021/2
Y1 - 2021/2
N2 - Many animals are sexually dimorphic, whereby males may display brighter body coloration and more distinctive ornamentation than females. Fishes in temperate regions markedly change their energy allocation toward reproduction in response to the seasonal environment. Seasonal change in reproductive investment affects the expression of sexually dimorphic traits in males through gonadal weight change. Here, we report seasonal changes in body size, testis weight and sexual dimorphism of the fins (anal fin length and dorsal fin length) in the northern medaka Oryzias sakaizumii. Fish were collected periodically from a wild population (Aomori). Gonad weight increased from May to July in both males and females, corresponding to the reproductive season. Moreover, during this period, the degree of sexual dimorphism in fin length increased. To investigate the relationship between testis weight and individual differences in male fin length, we analyzed relationships among morphological traits using structural equation modeling. In the reproductive season, increased testis weight was associated with longer fin length in males, but the relationship disappeared after the reproductive season. These observations suggest that the sexually dimorphic fin in this fish is a mating signal. Results from a mating experiment also support this view. Males with larger size and/or longer fin attracted more mates than those with smaller fins, suggesting that sexual selection operates through females choosing to mate with males having longer fins.
AB - Many animals are sexually dimorphic, whereby males may display brighter body coloration and more distinctive ornamentation than females. Fishes in temperate regions markedly change their energy allocation toward reproduction in response to the seasonal environment. Seasonal change in reproductive investment affects the expression of sexually dimorphic traits in males through gonadal weight change. Here, we report seasonal changes in body size, testis weight and sexual dimorphism of the fins (anal fin length and dorsal fin length) in the northern medaka Oryzias sakaizumii. Fish were collected periodically from a wild population (Aomori). Gonad weight increased from May to July in both males and females, corresponding to the reproductive season. Moreover, during this period, the degree of sexual dimorphism in fin length increased. To investigate the relationship between testis weight and individual differences in male fin length, we analyzed relationships among morphological traits using structural equation modeling. In the reproductive season, increased testis weight was associated with longer fin length in males, but the relationship disappeared after the reproductive season. These observations suggest that the sexually dimorphic fin in this fish is a mating signal. Results from a mating experiment also support this view. Males with larger size and/or longer fin attracted more mates than those with smaller fins, suggesting that sexual selection operates through females choosing to mate with males having longer fins.
KW - Indicator signal
KW - Life-history adaptation
KW - Oryzias latipes species complex
KW - Seasonality
KW - Sexual dimorphism
UR - http://www.scopus.com/inward/record.url?scp=85100594849&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85100594849&partnerID=8YFLogxK
U2 - 10.1007/s10641-021-01059-x
DO - 10.1007/s10641-021-01059-x
M3 - Article
AN - SCOPUS:85100594849
VL - 104
SP - 107
EP - 118
JO - Environmental Biology of Fishes
JF - Environmental Biology of Fishes
SN - 0378-1909
IS - 2
ER -