Temporal and spatial opportunities for polygamy in a monogamous seahorse, Hippocampus whitei

Abstract

The sex with the higher potential reproductive rate is expected to mate polygamously unless there are temporal or spatial constraints on mate availability. We investigated whether such constraints were evident in a population of the monogamous seahorse Hippocampus whitei (family Syngnathidae). Across the whole study site, breeding was more asynchronous than expected by chance. Our findings are thus compatible with the hypothesis that asynchronous breeding may promote and/or maintain monogamy. Asynchrony per se was unlikely to explain monogamy entirely, however, as temporal opportunities for polygamy remained and the males that were nearest one another had the lowest level of asynchrony. Moreover, each animal's home range overlapped with home ranges of potential mates other than their partner, implying a lack of spatial constraints on polygamy. We suggest that H. whitei mated monogamously because the benefits of polygamy were reduced by (1) only small differences in the potential reproductive rates of males and females and/or (2) a mate familiarity effect that increased reproductive success in successive matings. Further research could investigate relationships between mating pattern and varying intersexual differences in potential reproductive rates across syngnathid species.

Striking a balance between retaining populations of protected seahorses and maintaining swimming nets

“…It was found that the population on the Manly net started breeding in late September and continued until the end of February during this 1 year study, but clearly the exact duration of breeding may vary between years. The abundance of seahorses decreased at the conclusion of the breeding season and it is believed they moved off the net into the surrounding seagrass meadows and deeper waters (Vincent, 1995;Vincent et al, 2004). This differs from the findings of Clynick (2008) who found no seasonal variation in seahorse populations on nets at Balmoral and Clifton Gardens.…”

The dynamics of reproductive rate, offspring survivorship and growth in the lined seahorse, Hippocampus erectus Perry, 1810

“…This is similar to the report that the difference in the reproductive rate of male and female Syngnathus typhle increases as the fish age (Svensson, 1988). However, this does not display that the older seahorses have better quality offspring, and the quality is generally correlated with the brood pouch development, gestation time and parental investment (Vincent et al, 2004; Lin et al, 2008; Naud et al, 2009). …”

“…In some syngnathid species, the reproduction is influenced by the complex brooding structure, brood pouch development, sexual selection, mating patterns and social promiscuity (Parker and Simmons, 1996; Carcupino et al, 2002; Wilson et al, 2003; Vincent et al, 2004; Lin et al, 2006; Naud et al, 2009). …”

The function of daily greetings in a monogamous pipefish Corythoichthys haematopterus

“…In this fish family, monogamy is widely distributed regardless of the complexity of the brood pouch, phylogenetic relationship and geographical distribution (Wilson et al, 2001(Wilson et al, , 2003. All monogamous syngnathids so far reported are non-territorial, and home ranges of individuals overlap with each other (Matsumoto & Yanagisawa, 2001;Vincent et al, 2004). Therefore, limited availability of mates or resources does not seem to explain the maintenance of their monogamy.…”