Reproductive Systems, Transfer and Digestion of Spermatophores in Two Asian Luciolinae Fireflies (Coleoptera: Lampyridae)

The internal reproductive anatomy of males and females of two Asian Luciolinae fireflies Emeia pseudosauteri (Geisthardt, 2004) and Abscondita chinensis (L., 1767) is described, and the time course for spermatophore transfer and digestion examined. E. pseudosauteri is sexually dimorphic, with a flightless female, and Abs. chinensis is sexually monomorphic, with the female flighted. Both are monandrous. Possible female accessory glands are described for the first time for both species. An overview of present knowledge of female reproductive anatomy in the Luciolinae reveals males of 18 species in 10 genera may produce spermatophores and permits speculation about spermatophore production in another 16 genera.

'Superbull' males: what role do they play and what drives their appearance within the Doryteuthis gahi Patagonian Shelf population?

Cephalopod populations exhibit high variability in life history characteristics, such as longevity and size-at-age. The aim of this study was to understand how characteristics of a newly described ‘superbull’ male morph in Doryteuthis gahi populations (Patagonian Shelf) arise and whether there is a selective advantage. At the population level, it is speculated that superbulls provide temporal and spatial connectivity, but individual benefit is less obvious. Age structure and reproductive potential of males was investigated to determine whether superbulls could provide connectivity. Environmental variables affecting size-at-age were explored to ascertain whether morphological differences were primarily phenotypically driven. Superbulls from the autumn spawning cohort were significantly older than the residual population, with added longevity potentially leading to spawning with the following cohort. A reduction in relative testis weight was apparent in superbulls, but spermatophore production remained high. Generalised additive mixed models indicated temperature, location and hatch year had significant effects on size-at-age. Weak correlations between warm El Niño–Southern Oscillation phases and superbull abundance were found. The results suggest that superbulls provide temporal connectivity and arise through phenotypic plasticity, likely providing connectivity as a side effect of body shape and size rather than a genetically selected advantage.

The effect of parental size on spermatophore production, egg quality, fertilization success, and larval characteristics in the Caribbean Spiny lobster, Panulirus argus

The average size of spiny lobsters (Decapoda; Palinuridae) has decreased worldwide over the past few decades. Market forces coupled with minimum size limits compel fishers to target the largest individuals. Males are targeted disproportionately as a consequence of sexual dimorphism in spiny lobster size (i.e. males grow larger than females) and because of protections for ovigerous females. Therefore, overexploitation of males has led to sperm limitation in several decapod populations with serious repercussions for reproductive success. In the Caribbean spiny lobster, Panulirus argus, little is known about the effect of reduced male size on fertilization success or the role that individual size plays in gamete and larval quality. We conducted a series of laboratory experiments to test the relationship between male size and spermatophore production over multiple mating events and to determine whether spermatophore reduction and female size affected fertilization success or larval attributes in P. argus in the Florida Keys, FL (USA). We found that over consecutive matings, larger males consistently produced spermatophores of a greater weight and area than smaller males, although size-specific differences in sperm cell density were undetected and probably obscured by high variance in the data. Where spermatophores were experimentally reduced to mimic the decline in spermatophore size with declining male size, fertilization success (the number of fertilized eggs/total number of eggs extruded) declined, indicating that sperm availability is indeed limited. No maternal size effects on egg size or quality (C:N ratio) or larval quality (size, swimming speed, mortality) were observed. Our results demonstrate the importance of maintaining large males in populations of P. argus to ensure fertilization success and caution against their overexploitation through fishing, which may severely reduce reproductive success and thus population sustainability.

Male–male competition leads to less abundant but more attractive sperm

Males employ complex strategies to optimize their reproductive success when faced with male–male competition; for instance, they can adjust the ejaculate characteristics. In copulating species, a male may also strategically adjust his ejaculate expenditure according to female quality. Quantifying the relative contribution of ejaculate plasticity in male reproductive success is often difficult, especially when females exert postcopulatory cryptic choice. One way to quantify the functional significance of ejaculate plasticity is offered by mating systems in which the reproductive partners do not meet each other during insemination. In the collembolan Orchesella cincta , males deposit their ejaculates (spermatophores) irrespective of the presence of females. We tested whether Orchesella males adjust spermatophore number when exposed to the presence of another male and whether changes in spermatophore production influence female choice. We found that Orchesella males display plasticity in spermatophore allocation. Males decreased the spermatophore number when exposed to a rival male. Moreover, females preferentially took up spermatophores of males that were exposed to a competitor. The reduction in spermatophore number suggests, besides an adaptive response to the risk of ejaculate removal by rival males, an optimization strategy owing to the costs of more attractive spermatophores.