Variation in reproductive strategies of Embiotocids: a comparative approach

Reproductive strategies of marine fishes are diverse, surfperches (Embiotocidae) represent a unique family of viviparous fishes that exhibit internal fertilization, gestation to the sub-adult stage, and live-birth. Maternal investment is extremely high in surfperches, which invokes the expectation that broodsize is limited, and females should be selective and choose few mates, yet polyandry occurs in all six species examined to date. Surfperches are found in the northern Pacific in temperate waters with the majority of species residing along the coast o f the eastern Pacific. Our study characterized the reproductive life history of calico surfperch (Amphisticus koelzi) which is the only species o f surfperch missing from previous literature, as well as assigned paternity with the utilization of RADseq. All calico surfperch broods examined were sired by multiple fathers, and the number of fathers ranged from four to eight. Additionally, we compared the reproductive strategy of Western Pacific surfperches (including calico surfperches) to an Eastern Pacific species of surfperch Ditrema temminchii by assigning paternity. We discovered that the prevalence o f multiple paternity in Eastern Pacific surfperches ranges from 92-100%, however, the prevalence of multiple paternity is noticeably reduced in D. temminckii with only 60% of broods being sired by multiple fathers. In addition, the total number o f sires per brood is lower compared to the Eastern Pacific surfperches, suggesting a different mating strategy. The average number o f sires was 1.86 per brood, and paternity was skewed, indicating the majority o f paternity was allocated to a single male. The number of fathers is an accurate approximation for the number of mates in D. temminckii, which was examined by genotyping spermatozoa within the uterine sacs o f females (sperm donors) and sires within broods (paternal contributors). The contrast in the frequency of multiple paternity in D. temminckii with eastern Pacific surfperches suggests variation in the mating strategy that may be associated with a stronger female choice on males.