Reason for being single: some males do not guard receptive females in the hermit crab Pagurus filholi

Size‐dependent mating preference of the male fiddler crab Austruca perplexa

“…In some iteroparous animals, however, body size increases continuously after maturation, and attractiveness is often increased with body size (Backwell & Jennions, ; Callander et al, ; Downhower et al, ; McComb, ; Wilbur et al, ). In such cases, larger males invest more in reproduction and enjoy the benefits of their greater attractiveness (Hasaba, Yasuda, & Wada, ; Kvarnemo et al, ; Shine et al, ; Tejedo, ); they may also become more choosy, as we show in the present study. In sticklebacks, for example, attractive (brighter and larger) males tend to be choosier and they choose big females (Bakker & Rowland, ; Kraak & Bakker, ).…”

“…Male fiddler crabs wave slowly when the intensity of competition is low, females are small, and when females come very near and show their mating choice (Reading & Backwell, ; Tina, ; Tina et al, ). However, though small males spend less time and energy on courting females, they spend more time on feeding (Callander et al, ; Tina et al, ), perhaps because greater investment in feeding increases their growth rate and future reproductive success (Hasaba et al, ; Muramatsu, ; Tejedo, ). Once they grow in size, they will be preferred by females and will have a greater chance to acquire mates and maximize their reproductive fitness.…”

“…Generally, in fiddler crabs, small males invest less energy in courting females compared to large males (Callander et al, 2012;Hayes et al, 2013;Jennions & Backwell, 1998 Not only in fiddler crabs but also in several other animals, small males invest less in reproductive functions than large males. For example, small natterjack toad, bluegill, and hermit crab males show less chorus attendance at breeding sites, less nesting frequency and less guarding frequency to receptive females, respectively (Hasaba et al, 2015;Jennings et al, 1997;Tejedo, 1992). This may occur for several reasons.…”

“…However, though small males spend less time and energy on courting females, they spend more time on feeding (Callander et al, 2012;Tina et al, 2016c), perhaps because greater investment in feeding increases their growth rate and future reproductive success (Hasaba et al, 2015;Muramatsu, 2010;Tejedo, 1992). Once they grow in size, they will be preferred by females and will have a greater chance to acquire mates and maximize their reproductive fitness.…”

Regeneration of major cheliped after the mating season in the hermit crab <i>Pagurus middendorffii</i>

“…In P. middendorffii and P. nigrofascia, their mating seasons are limited to about one month and females produce only one clutch per year (Wada et al, 1995;Goshima et al, 1996), and almost all males immediately guard receptive females Suzuki et al, 2012). On the other hand, P. filholi have a longer reproductive season (about 8 months) with laying several clutches (Goshima et al, 1998), and males do not guard receptive females especially when the males would molt within 5 days (Hasaba et al, 2015). Therefore in P. middendorffii and P. nigrofascia the opportunity for mating is more limited than P. filholi, and an investment for major cheliped regeneration in the mating season in P. middendorffii would potentially be restricted by constraints related to the physiological reproductive status.…”