Advances in Reproductive Science for Wild Carnivore Conservation

Knowledge about reproduction is critical for predicting the viability of wildlife populations in nature and for managing breeding programmes in captivity. Intensive species-based studies are the priority, because reproductive mechanisms are extraordinarily diverse, even within the same taxonomic family. Carnivores deserve more attention as such species are highly vulnerable to environmental change and human persecution. The present review provides contemporary illustrations of how reproductive science is contributing to understand unique reproductive mechanisms that are both of fundamental and applied interest. In the case of the endangered African wild dog ( Lycaon pictus ) free-living in South Africa, non-invasive faecal corticosteroid assessments have yielded new insights about the impact of animal relocation and reintroduction on adaptive responses, reproductive fitness and survival. For the maned wolf ( Chrysocyon brachyurus ), advances have been made in characterizing and comparing reproductive traits in free-ranging vs captive individuals. For the cheetah ( Acinonyx jubatus ), recent studies have focused on the cryosensitivity of sperm and the ability to develop a field-friendly sperm cryo-method. The by-product has been a large-scale frozen repository of sperm from wild-caught cheetahs useful for infusing new genes into ex situ populations. Finally, rigorous, multi-disciplinary and cross-institutional reproductive studies of the black-footed ferret ( Mustela nigripes ), including the use of artificial insemination, have contributed to the remarkable recovery and restoration of this species, once on the brink of extinction. In summary, advances in reproductive science are not necessarily related to 'assisted breeding'. However, understanding the unique ways of carnivore reproduction greatly contributes to species management and conservation.     

Determination of the optimal feeding rate and light regime conditions in juvenile burbot, Lota lota (L.), under intensive aquaculture

The aim of the study was to optimize burbot juveniles rearing in recirculating aquaculture system. In experiment 1 (17 °C, photoperiod 24L:0D), the fish (initial: body weight [W] = 15.36 ± 3.72 g, standard length [SL] = 12.48 ± 1.09 cm) were divided into four groups (I, II, III and IV). Different feeding levels were applied: 1, 2, 3 and 4 % of biomass daily (counted based on dry feed weight). The feed conversion ratio (FCR) and specific growth rate (SGR) were recorded. In experiment 2 (17 °C, feeding level of 2 % of biomass day^?1), fish (W = 5.24 ± 2.43 g and SL = 8.54 ± 1.24 cm) were divided into two groups where different light conditions were applied (I: 24 h light [1,800 lx] and II: 24 h darkness [4 lx]). In experiment 1, the highest SGR was recorded in group II (1.93 % day^?1), whereas the lowest SGR (1.27 % day^?1) and final W (P < 0.05) was in I group. The lowest (P < 0.05) FCR (0.63) was in group II. In the remaining groups, FCR was similar (0.68–0.70, P > 0.05). The feed consumption in group I reached 100 %, in group II, it was 71.3 % (P < 0.05) and it was the lowest in groups III (39.26 %) and IV (36.93 %). In experiment 2 no differences in the growth and survival rate were recorded (final SL between 14.16 and 14.19 cm, P > 0.05; W between 23.33–23.35 g; P > 0.05). The results from experiment 1 indicate that the feeding 2 % of biomass day^?1 was the most efficient. Also, it was proven, for the first time, that there was no effect of using different constant light conditions.     

Salinity effects on reproduction of giant freshwater prawn Macrobrachium rosenbergii (de Man)

Understanding the role of salinity in breeding and growth has the potential to enhance production of giant freshwater prawn, Macrobrachium rosenbergii. This study investigated the reproduction of females reared in salinities of 0, 6, 12, and 18 g L^− 1. Mean weight of females decreased with increased salinity (31.40 ± 1.54, 25.14 ± 1.16, 20.80 ± 0.81, and 16.62 ± 1.04 g at 0, 6, 12, and 18 g L^− 1, respectively). Larval production was delayed by 2 months in females reared in 12 g L^− 1 compared to 6 and 0 g L^− 1 and the cumulative number of berried females decreased with increased salinity. The number of larvae produced was positively correlated to weight of female. A larval production not only differed between salinity treatments, but also that larval production per gram of female differed between treatments. Females reared in lower salinity of 0 and 6 g L^− 1 produced larger numbers of larvae (12,155 ± 480 and 6519 ± 323, respectively) compared to 12 and 18 g L^− 1 (3751 ± 256 and 0, respectively). The number of larvae produced per gram of female was inversely related to the salinity levels (Y = − 37.54X + 685.65, n = 339, r² = 0.995, p < 0.05). Survival of larvae from females reared at 0 and 6 g L^− 1 was higher than those from females reared in 12 g L^− 1. This study clearly shows that female broodstock reared in lower salinity was larger, reproduced early, and produced more offspring than at higher salinity and this could significantly impact coastal prawn culture where seasonal fluctuation of salinity in the hatchery is common.     

Fertilization efficiency of cryopreserved sperm from striped catfish, Pangasius hypophthalmus (Sauvage)

The fertilization efficiency of cryopreserved sperm was compared with fresh sperm from striped catfish, Pangasius hypophthalmus . Of the two sets of experiments carried out, the first compared four sperm doses using fresh sperm and fresh eggs. The second experiment compared six concentrations of cryopreserved sperm ranging from 6.94 × 10⁷ to 6.94 × 10¹⁰ to fertilize 100 eggs per batch. Fertilization, hatch and survival rates were compared between cryopreserved and fresh sperm. The highest fertilization rate (53.75±1.62%) was achieved with a sperm dose of 6.94 × 10⁸. Increasing the sperm dose to 3.47 × 10⁹ did not increase the fertilization rate, indicating that the optimum sperm:egg ratio lies between 6.94 × 10⁶ and 3.47 × 10⁷ sperm per egg. Both highest (6.94 × 10¹⁰) and the lowest (6.94 × 10⁷) sperm doses resulted in lower fertilization rates (2.04% and 16.90% respectively). No significant differences were found among four fresh sperm doses compared. Mean hatch and survival rates resulting from fresh and cryopreserved sperm were similar. The experiment shows that while only 1.89 × 10⁶ fresh spermatozoa was required to fertilize a fresh egg, 6.94 × 10⁶ (or 3.67 times more) cryopreserved sperm was required to achieve the same level of fertilization. This provides important information for making decision to cryopreserve sperm for commercial and/or conservation purposes.     

Phylogeography and conservation gaps of Musa balbisiana Colla genetic diversity revealed by microsatellite markers

Genetic Resources and Crop Evolution - Collection and storage of crop wild relative (CWR) germplasm is crucial for preserving species genetic diversity and crop improvement. Nevertheless, much of...