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Fig. 5 in Fig. 7 in Reproduction of the Blue Jack Mackerel, , in Western Portugal: Microscopic Gonad Analysis Reveals Indeterminate Fecundity and Skipped Spawning Patterns.

Fig. 5. Mean (± standard error) gonadosomatic index (GSI), hepatosomatic index (HSI), and relative condition (Kn) for blue jack mackerel (Trachurus picturatus) females off the western coast of Portugal by maturation phase and abnormal condition. I, immature; D, developing; SC, spawning capable; AS, actively spawning; RS, regressing; RN, regenerating; CS, reproductive inactive ovaries with cystic structures; MA, spawning capable individuals with massive atresia; K, Kudoa spp.-infected ovaries. Sample size for each group is given between brackets in the x-axis.

Fig. 4 in Fig. 7 in Reproduction of the Blue Jack Mackerel, , in Western Portugal: Microscopic Gonad Analysis Reveals Indeterminate Fecundity and Skipped Spawning Patterns.

Fig. 4. Histological sections of ovaries of blue jack mackerel (Trachurus picturatus) with abnormalities: a) reproductive inactive ovaries with cystic structures with only PG and early SG oocytes (female with 38.1 cm TL, caught in the first half of January); b) reproductive inactive ovaries with massive cystic structures with only a few PG oocytes remaining (female with 26.2 cm TL, caught in the first half of March); c) spawning capable individuals with massive atresia (female with 25.8 cm TL, caught in second half of February); d) Kudoa spp.-infected ovary (female with 25.5 cm TL, caught on the first half of March); e) actively spawning (female with 31.1 cm TL, caught on the second half of March); f) regressing female with massive atresia (female with 27.3 cm TL, caught in April). *, Kudoa spp. infection; AVTG, advance vitellogenic oocytes; At, atresia; AtSt, atretic structures; CA, cortical alveoli oocytes; EVTG, early vitellogenic oocytes; H, hydrated oocytes; PG, primary growth oocytes.

Fig. 3 in Fig. 7 in Reproduction of the Blue Jack Mackerel, , in Western Portugal: Microscopic Gonad Analysis Reveals Indeterminate Fecundity and Skipped Spawning Patterns.

Fig. 3. Mean (± standard error) gonadosomatic index (GSI), hepatosomatic index (HSI), and relative condition (Kn) for blue jack mackerel (Trachurus picturatus) females (black dots) and males (open triangles) off the western coast of Portugal by sampling date. Sea surface temperature (SST, grey shadow). 1st half, month first fortnight; 2nd half, month second fortnight.

Fig. 7 in Fig. 7 in Reproduction of the Blue Jack Mackerel, , in Western Portugal: Microscopic Gonad Analysis Reveals Indeterminate Fecundity and Skipped Spawning Patterns.

Fig. 7. Relationships between batch fecundity and total length (TL) and eviscerated weight (EW) for blue jack mackerel (Trachurus picturatus) females caught off the western coast of Portugal.

Fig. 2 in Fig. 7 in Reproduction of the Blue Jack Mackerel, , in Western Portugal: Microscopic Gonad Analysis Reveals Indeterminate Fecundity and Skipped Spawning Patterns.

Fig. 2. Maturity phase frequency by sampling date for blue jack mackerel (Trachurus picturatus) females and males caught off the western coast of Portugal. D, developing; SC, spawning capable; AS, actively spawning; RS, regressing; RN, regenerating. 1st half, month first fortnight; 2nd half, month second fortnight.

Fig. 6 in Fig. 7 in Reproduction of the Blue Jack Mackerel, , in Western Portugal: Microscopic Gonad Analysis Reveals Indeterminate Fecundity and Skipped Spawning Patterns.

Fig. 6. Fecundity type of blue jack mackerel (Trachurus picturatus) off the western coast of Portugal, assessed from the variation throughout the spawning season of a) oocyte size frequency distribution; b) abundance of early developing oocytes (white) and advanced vitellogenic oocytes (grey); c) mean oocyte diameter (OD) of the advanced vitellogenic oocytes. Boxplot represents median, first and third quartiles, whiskers represent 1.5 × interquartile range and dots are possible outliers. 1st half, month first fortnight; 2nd half, month second fortnight.

Fig. 1 in Fig. 7 in Reproduction of the Blue Jack Mackerel, , in Western Portugal: Microscopic Gonad Analysis Reveals Indeterminate Fecundity and Skipped Spawning Patterns.

Fig. 1. Map of Portugal showing the continental slope: the surveys were conducted along the coast at 20–300 m deep (represented by the rectangle in the figure).

opencc-zeroAug 2022View details →

dryad36/100

Intercolony variation in reproductive skipping in the African penguin mark-recapture data

In long-lived species, reproductive skipping is a common strategy whereby sexually mature animals skip a breeding season, potentially reducing population growth. This may be an adaptive decision to protect survival or a non-adaptive decision driven by individual-specific constraints. Understanding the presence and drivers of reproductive skipping behaviour can be important for effective population management, yet in many species such as the endangered African penguin (Spheniscus demersus), these factors remain unknown. This study uses multistate mark-recapture methods to estimate African penguin survival and breeding probabilities at two colonies between 2013 and 2020. Overall, survival (mean ± SE) was higher at Stony Point (0.82 ± 0.01) than Robben Island (0.77 ± 0.02). Inter-colony differences were linked to food availability; under decreasing sardine (Sardinops sagax) abundance, survival decreased at Robben Island and increased at Stony Point. Additionally, reproductive skipping was evident across both colonies; at Robben Island, the probability of a breeder becoming a nonbreeder was ~0.22, versus ~0.1 at Stony Point. Penguins skipping reproduction had a lower probability of future breeding than breeding individuals; this lack of adaptive benefit suggests reproductive skipping is driven by individual-specific constraints. Lower survival and breeding propensity at Robben Island places this colony in greater need of conservation action. However, further research on the drivers of inter-colony differences is needed.

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Intercolony variation in reproductive skipping in the African penguin mark-recapture data

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publicAug 2022View details →

opencc-zeroDec 2017View details →

Data from: The insensitive dormouse: reproduction skipping is not caused by chronic stress in Glis glis

Entire populations of edible dormice (Glis glis) can skip reproduction in years without mast seeding of deciduous trees (particularly beech or oak seed), because juveniles require high caloric seeds for growth and fattening prior to hibernation. We hypothesized that, in mast failure years, female dormice may be forced to spend larger amounts of time foraging for low-quality food, which should increase their exposure to predators, mainly owls. This may lead to chronic stress, i.e., long-term increased secretion of Glucocorticoids (GC), which can have inhibitory effects on reproductive function in both female and male mammals. We monitored reproduction in free-living female dormice over three years with varying levels of food availability, and performed a supplemental feeding experiment. To measure stress hormone levels, we determined fecal GC metabolite (GCM) concentrations collected during the day, which reflect hormone secretion rates in the previous nocturnal activity phase. We found that year-to-year differences in beech mast significantly affected fecal GCM levels and reproduction. However, contrary to our hypothesis, GCM levels were lowest in a non-mast year without reproduction, and significantly elevated in full-mast and intermediate years, as well as under supplemental feeding. Variation in owl density in our study area had no influence on GCM levels. Consequently, we conclude that down-regulation of gonads and reproduction skipping in mast-failure years in this species is not caused by chronic stress. Thus, in edible dormice, delayed reproduction apparently is profitable in response to the absence of energy-rich food in non-mast years, but not in response to chronic stress.

opencc-zeroDec 2017View details →

Data from: Reproductive skipping as an optimal life history strategy in the southern elephant seal, Mirounga leonina

Intermittent breeding by which organisms skip some current reproductive opportunities in order to enhance future reproductive success is a common life history tradeoff among long-lived, iteroparous species. The southern elephant seal Mirounga leonina engages in intermediate breeding when body condition is low. While it is anticipated that this strategy may increase the lifetime reproductive output of this species, the conditions under which reproductive skipping are predicted to occur are not clear. Here I develop a dynamic state variable model based on published data that examines when southern elephant seals are predicted to optimally skip reproduction in order to maximize lifetime reproductive output as a function of current body mass, maternal age, and survivorship. I demonstrate that the optimal reproductive strategy for this species can include reproductive skipping, and that the conditions where this is optimal depend on patterns of mass-dependent adult female survival. I further show that intermittent breeding can increase lifetime reproductive output, and that the magnitude of this benefit increases with the ability of individual animals to replenish depleted body mass through foraging. Finally, I show that when the environment is variable and foraging is reduced in bad years, the benefit of adopting an optimal strategy that includes reproductive skipping increases asymptotically with the frequency of bad years. These results highlight the importance of characterizing the pattern of adult survival in this species, as well as the need to identify other factors that may influence the prevalence and benefits of reproductive skipping.

publicJul 2019View details →

Data from: Reproductive skipping as an optimal life history strategy in the southern elephant seal, Mirounga leonina

Open the record for dataset details and reuse information.