ID 38265
File
language
eng
Author
Iida, Tomohiro
Sato, Noriyosi
Sauer H. H. Warwick
Iwata, Yoko
Description
Emergence of male dimorphism within a species is the evolutionary process of disruptive selection. In squids, two types of male mating behaviour, known as alternative reproductive tactics (ARTs), are causally associated with adult body size. Males inseminate promiscuously with the same females; large “consort” males internally, and small “sneaker” males externally. Previously we found that in Heterololigo bleekeri, sneaker (but not consort) spermatozoa are able to swarm by sensing self-emitted CO_2. This suggests that a swarming trait might have arisen in sneakers as a “sperm cooperation” strategy among sibling sperm in order to compete with consort males, or as a consequence of adaptation to external fertilization. To address these possibilities, we examined six species where three patterns of insemination are present, namely, only internal, only external, or both ARTs. In three species that employ both ARTs (H. bleekeri, Loligo reynaudii and Uroteuthis edulis), sneaker spermatozoa always exhibited self-swarming capacity. In Idiosepius paradoxus and Todarodes pacificus, which use only external insemination, spermatozoa formed a swarm. However, in Euprymna morsei, which use only internal insemination, sperm were unable to swarm. These results suggest that the self-swarming trait is likely to be linked to the mode of insemination rather than the alternative strategy used by sneaker males. Thus we propose a new hypothesis in which cooperative sperm behaviour has evolved not only through kin selection against sperm competition risks, but also through adaptation to the insemination/fertilization environment.
Subject
Alternative reproductive tactics
Sperm traits
Sperm competition
Mating behaviour
Fertilization
Journal Title
Reviews in fish biology and fisheries
Volume
26
Issue
3
Start Page
601
End Page
607
ISSN
09603166
Published Date
2016-09
DOI
DOI Date
2016-12-14
NCID
AA10940620
Publisher
Springer International Publishing
NII Type
Journal Article
Format
PDF
Rights
The final publication is available at Springer via http://dx.doi.org/10.1007/s11160-016-9434-1.
Text Version
著者版
OAI-PMH Set
Education and Research Center for Biological Research, Faculty of Life and Environmental Science