Evidence for use of both capital and income breeding strategies in the mangrove tree crab, Aratus pisonii

Two common strategies organisms use to finance reproduction are capital breeding (using energy stored prior to reproduction) and income breeding (using energy gathered during the reproductive period). Understanding which of these two strategies a species uses can help in predicting its population dynamics and how it will respond to environmental change. Brachyuran crabs have historically been considered capital breeders as a group, but recent evidence has challenged this assumption. Here, we focus on the mangrove tree crab, Aratus pisonii, and examine its breeding strategy on the Atlantic Florida coast. We collected crabs during and after their breeding season (March–October) and dissected them to discern how energy was stored and utilized for reproduction. We found patterns of reproduction and energy storage that are consistent with both the use of stored energy (capital) and energy acquired (income) during the breeding season. We also found that energy acquisition and storage patterns that supported reproduction were influenced by unequal tidal patterns associated with the syzygy tide inequality cycle. Contrary to previous assumptions for crabs, we suggest that species of crab that produce multiple clutches of eggs during long breeding seasons (many tropical and subtropical species) may commonly use income breeding strategies.

Pre-breeding Diets in the Seahorse Hippocampus reidi: How Do They Affect Fatty Acid Profiles, Energetic Status and Histological Features in Newborn?

Seahorses (Hippocampus spp.) are exceptional marine species considering their reproductive patterns and other features. Due to the iconic characteristics of these fishes, aquarium trade, and research efforts have increased in the last years. Consequently, novel rearing techniques have been developed; however, there is a need for improvements on a series of issues, namely reproduction success enhancement. The tropical species Hippocampus reidi is the most traded seahorse but many aspects of breeding and its impact on the quality of neonates are still poorly understood. In the present study, we assessed the effects of two pre-breeding diets on newborn quality and viability considering biochemical characteristics, energetic status, and ultrastructural aspects of muscular tissue. During the whole pre-breeding season (5 months), the breeders were fed on one of the following diets: M0 (adult non-enriched Artemia) and M5 (adult non-enriched Artemia + mysidaceans). From the onset of the reproduction period, all breeders were fed for 6 months on diet M5. Breeding success and energetic status (ATP, total adenylic nucleotides, AEC, and NAD) of newborns resulted considerably enhanced in treatment M5. However, initial differences in neonates quality did not affect further newborn performance (survival and growth until day 7 after male’s pouch release) while gaining access to high-quality preys (copepods). Besides, morphological alterations in muscle tissue were not observed. The reproduction in the species followed a capital–income continuum pattern characterized by an initial mixed capital-income period (until 70–100 days since the onset of the breeding season) followed by an income breeding period with progressive exhaustion of body reserves, especially in M0-newborns. Interestingly, the effects of pre-breeding diets were also noticed in the second half of the breeding period. Our results seemed to indicate that the requirements in essential fatty acids in H. reidi are lower than in other seahorse species (e.g., Hippocampus guttulatus). Globally, the results achieved revealed that high-quality pre-breeding diets enhanced reproduction success and would likely result advantageous to improve newborn endurance in conditions of moderate starvation or sub-optimal feeding.

Capital-income breeding in wild boar: a comparison between two sexes

Organisms differ in the strategy adopted to fuel reproduction by using resources either previously acquired and stored in body reserves (capital breeding) or, conversely, acquired during their reproductive activity (income breeding). The choice of one or the other strategy is related to several internal and external factors which are counteractive in wild boar. Based on a large dataset of culled wild boar, we investigated individual body weight variability throughout the period of 1st September–31st January, which included the main part of the mating season, among different sex and age classes to determine their position along the capital-income breeding continuum. Though food resources were abundant during the rut, adult males lost body weight suggesting they adopted a predominantly capital breeding strategy, likely owing to the high intra-sexual competition entailed by the peculiar mating system of the species. On the contrary, subadult males seemed to behave as income breeders, likely enhancing the reproductive flexibility of wild boar populations. During the rut, females stored reserves, thus suggesting that they substantially relied on them to cover future reproductive costs.

Reproductive patterns and energy management strategies of females of the fiddler crab Leptuca uruguayensis with short reproductive seasons

Reproduction is a costly process that depends on the management of available resources. Here, we aimed to understand the energetic strategies of females of the fiddler crab Leptuca uruguayensis (Nobili 1901), in a population with short reproductive seasons. For this, we developed an integrated approach to recognize the brooding time, spawning pattern modulated by female size, number of spawns per female, and content of reserves in the ovary and hepatopancreas. Based on the condition of the ovary and hepatopancreas, the reproductive season was divided into three periods. In each of these periods, it was possible to record a spawning event, which was mainly represented by large females. Most of the females had one spawn during the breeding season, and only large females had two spawns, with an interval of approximately two months. We propose that L. uruguayensis presents a mixed capital-income breeding strategy associated with the female size and period of the reproductive season. We conclude that large females make the greatest reproductive effort for the population, because they can have two spawns, whereas medium and small females make a low contribution because they are still investing energy in somatic growth to increase fecundity in the next reproductive season.

Technical Efficiency Analysis of Millet Production in the Sahel Region of Burkina Faso

Millet is the basic cereal crop which contributes to rural households’ food security in the Sahel region of Burkina Faso. This study assesses the technical efficiency and its determinants of millet farmers in this region. A stochastic frontier approach is followed to analyze data collected on 106 households randomly selected in 2017. The mean technical efficiency is estimated at 71.23% implying that millet production may be increased by 28.77% with the same resources used by farmers. The results show that formal education, off farm income, breeding, and access to credit are the main factors affecting the production efficiency. The study recommends decisions makers to take appropriate measures regarding these factors, to enhance millet productivity in the Sahel region.