Differential investment in male accessory glands: lessons from a marine fish with alternative reproductive tactics

Seminal fluid and accessory male investment in sperm competition

“…(Associated sperm trait plasticity is based on the same study unless additional sources are cited.) plainfin midshipman fish, Porichthys notatus guarder versus sneaker alternative reproductive tactics accessory glands-lobules and total accessory gland mass (but not nodes) relatively larger in guarders [83] yes-evidence for trade-off: sneaker males have relatively larger testes and much larger ejaculates, but guarders have higher sperm velocity owing to lobule secretions black goby, Gobius niger guarder versus sneaker alternative reproductive tactics accessory glands-seminal vesicles and mesorchial glands larger in guarder males [84] yes-evidence for trade-off: sneaker males have larger testes; seminal fluid enhances the velocity and fertilization ability of guarder sperm [85] grass goby, Zosterisessor ophiocephalus large (guarder) versus small (sneaker) males seminal vesicles-larger in larger (guarder) males [86] yes-evidence for trade-off, because testes larger in smaller (sneaker) males Chinook salmon, Oncorhynchus tswatchysha jack versus hooknose alternative reproductive tactics seminal fluid proteome [87] yes-jacks (sneakers) have relatively larger testes and faster sperm [88]; seminal fluid can affect own and rival sperm velocity [89] ant, Cardiocondyla obscurior winged versus wingless males seminal fluid proteome-56 out of 920 spots differed in intensity [90] yes [91]. with more rivals (but see [92]) [93] yes-daily sperm production rate and epididymal sperm numbers increase with more rivals [92] bank vole, Myodes glareolus number of rival male odours seminal vesicle size [94] no-testis size, epididymal sperm counts, daily sperm production and sperm motility all unaffected fruit fly, Drosophila melanogaster sperm competition intensity cues seminal fluid gene expression (2 out of 3 genes investigated) [95] n/a population density during larval development sex peptide and ovulin expression [96] n/a larval density, presence/absence of adult males during larval development accessory gland size-larger in response to competitive cues [97] no-testis size unaffected or reduced by same cues socio-sexual environment seminal fluid gene expression 2, 26 and 50 h after exposure to rivals (complex responses across genes and replicates) [98] n/a (Continued.…”

Physiology, endocrinology and chemical communication in aggressive behaviour of fishes

“…Sneakers are usually smaller and behave like females to access the territory without being confronted by the dominant male, and ultimately fertilize a proportion of the ova (Taborsky, 1994). Sneaking is an interesting strategy from the chemical communication point of view as sneakers must either be “pheromonally silent” (Locatello et al ., 2002; Miller et al ., 2019) or mimic females in odour as well as looks. One example is the G. niger , wherein parental males release a sex pheromone produced in the mesorchial gland that attracts females and induces aggressive displays in other males (Locatello et al ., 2002).…”

“…In this species, the dominant male accessory glands may play a role not only in parental care but also in pheromonal signalling. Again, sneakers have smaller accessory glands (Miller et al ., 2019). In S. pavo , male sneakers lack both the anal gland and the accessory testicular organs, suggesting that this renders them chemically undetectable by conspecifics (Barata et al ., 2008b).…”

Tactic-specific antimicrobial activity suggests a parental care function for accessory glands in a marine toadfish

“…Our previous work has shown that accessory glands are much larger in guarder males than in sneaker males, and that these glands play a role in sperm performance by increasing sperm velocity [20]; however, other possible functions for these glands have not been investigated. The plainfin midshipman accessory glands have two distinct structures: nodes and lobules (figure 1a), with guarder males investing more in the lobule mass than sneakers [20]. Why such differences exist between male types and what function is served by the accessory glands have been long-standing questions [24][25][26].…”

“…The plainfin midshipman fish (Porichthys notatus) has both a structurally complex accessory gland (figure 1a) and two alternative reproductive tactics [19,20]. Every spring, large 'guarder' males excavate nests underneath rocks and produce a low-frequency hum that attracts females [19].…”