All or nothing: Switch to high current reproductive investment under risk of starvation in male kelp crab

Abstract

One of the key features in reproduction of polygynous species is seminal recovery after mating. However, it is poorly known how environmental factors affect the recuperation period of seminal material. This study aims to test plasticity in recovery of seminal reserves in response to distinct environmental conditions of the kelp crab Taliepus dentatus. Male crabs were maintained after depletion of seminal reserves in one of eight different treatments in a factorial design of temperature (12 and 16°C), food availability (with alimentation and food deprivation), and time period (15 and 30 days), simulating different environmental situations in the laboratory to which the crab might be exposed to along its distribution. Temperature and food availability modulated the seminal recovery period in T. dentatus. Complete replenishment was reached within 30 days in all treatments (i.e., 12 and 16°C each with alimentation and food deprivation), but the highest recovery index was found in crabs without food provision (16°C). In this condition, the recovery index was twice as high compared with males maintained at a similar temperature but with feeding. Prolonged starvation at 16°C may be extremely stressful conditions for male crabs, during which risk to die probably triggered a concentration of the reproductive effort in favor of immediate reproduction. This suggests that plasticity of energy allocation toward reproduction may be expressed during extremely suboptimal conditions, which might be a similar strategy as proposed by the terminal investment hypothesis. The generally relatively fast seminal recovery regardless of the temperature may explain the kelp crab's continuous mating throughout the year.

Mating and ejaculate allocation pattern in the kelp crab Taliepus dentatus (Decapoda: Epialtidae)

“…The VSI in Metacarcinus edwardsii (Bell, 1835) and Lithodes santolla (Molina, 1782) are 0.14 % (recalculated according to Pardo et al, 2015) and 0.047 % (Pretterebner et al, 2019), respectively, but can also be as large as approximately 6 %, as in Homalaspis plana (H. Milne Edwards, 1834) (Pardo et al, 2019). Compared with these other species, the VSI of T. dentatus was intermediate and suggests that the kelp crab invests a significant part of its energy in reproductive development, constantly producing large quantities of seminal material and recovering it relatively fast after mating (Pretterebner and Pardo, 2020). The VSI has been calculated for other crustacean species, but based on wet weight and the entire body (with legs and chelae) weight (reviewed by Sainte-Marie, 2007).…”

“…Nauplius, 29: e2021012 investment of females (Baldanzi et al, 2018) and male seminal recovery (Pretterebner and Pardo, 2020). Knowledge about male reproductive biology is scarce despite them being the target of a fishery.…”

“…Experimental matings were conducted in the laboratory to describe the mating behavior of T. dentatus and to examine whether males have an ejaculate allocation pattern in response to their ontogenetic stage. Males (CL range: 87.3-119.8 mm) and females (CL range: 70.2-89.5 mm) of T. dentatus were collected from Los Molinos Bay and transported to the laboratory where crabs were maintained separately by sex in 500 l tanks with f lowing seawater, air supply (O 2 saturation was guaranteed through bubbling of water) and ad libitum food for at least 14 days to allow recovery of seminal material for mating (Pretterebner and Pardo, 2020). Experimental matings were conducted in all months from April 2017 to February 2018, except for May 2017.…”

Influence of mating strategies on seminal material investment in crabs

“…Mating with ‘hard-shelled’ females, energy-conserving short mate-guarding and the absence of costly prevention of competition (e.g. no sperm plug) may facilitate males of T. dentatus to recover seminal reserves fast (within 15 days) 61 and to increase the mating frequency. Although males of H. plana inverted the greatest quantity of energy in reproduction of the four species studied, this species normally does not perform post-copulatory guarding (LMP, pers.…”

Temporal and Spatial Signatures of Scylla paramamosain Transcriptome Reveal Mechanistic Insights into Endogenous Ovarian Maturation under Risk of Starvation

“…These include life history traits such as size at maturity, number of broods, fecundity, and size of eggs, as well as key reproductive processes like ovarian development and the synthesis of vitellogenin in crustaceans [8,9]. Variability in food availability is likely to lead to condition-dependent investments in reproduction [10]. Starvation constrains organisms in their allocation of energy to maintenance of body functions, somatic growth, and reproduction.…”