In this study, multiple paternity (MP) was investigated in three commercially important shark species, common smoothhound Mustelus mustelus, dusky shark Carcharhinus obscurus and scalloped hammerhead Sphyrna lewini occurring in southern Africa. Reduced marker panels of between five and six microsatellite loci were constructed for each species and used to genotype and assess the presence of MP in a total of 60 M. mustelus individuals from six litters, 90 C. obscurus individuals from 14 litters and 54 S. lewini individuals from 13 litters. Analysis in GERUD and COLONY revealed the presence of MP in all three species. Multiple paternities were observed in 67, 35 and 46% of the litters of M. mustelus, C. obscurus and S. lewini, with corresponding average sire size of 1·6, 1·4 and 2·0, respectively. The variation in the rate of MP among the three species is in accordance with previous studies whilst the comparatively high frequency of MP observed for M. mustelus, matches what has previously been reported for shark species demonstrating aggregation behaviour. 相似文献
The present histological study of adult female common smoothhound shark Mustelus mustelus demonstrates that the species can store sperm in their oviducal glands. In addition, single paternity of a litter of 22 pups is reported, contributing to further knowledge regarding the genetic and behavioural mating strategy of M. mustelus. 相似文献
Early developmental conditions contribute to individual heterogeneity of both phenotypic traits and fitness components, ultimately affecting population dynamics. Although the demographic consequences of ontogenic growth are best quantified using an integrated measure of fitness, most analyses to date have instead studied individual fitness components in isolation. Here, we estimated phenotypic selection on weaning mass in female southern elephant seals Mirounga leonina by analyzing individual‐based data collected between 1986 and 2016 with capture–recapture and matrix projection models. In support of a hypothesis predicting a gradual decrease of weaning mass effects with time since weaning (the replacement hypothesis), we found that the estimated effects of weaning mass on future survival and recruitment probability was of intermediate duration (rather than transient or permanent). Heavier female offspring had improved odds of survival in early life and a higher probability to recruit at an early age. The positive link between weaning mass and recruitment age is noteworthy, considering that pre‐recruitment mortality already imposed a strong selective filter on the population, leaving only the most ‘robust’ individuals to reproduce. The selection gradient on asymptotic population growth rate, a measure of mean absolute fitness, was weaker than selection on first‐year survival and recruitment probabilities. Weaker selection on mean fitness occurs because weaning mass has little impact on adult survival, the fitness component to which the population growth of long‐lived species is most sensitive. These results highlight the need to interpret individual variation in phenotypic traits in a context that considers the demographic pathways between the trait and an inclusive proxy of individual fitness. Although variation in weaning mass do not translate to permanent survival differences among individuals in adulthood, it explains heterogeneity and positive covariation between survival and breeding in early life, which contribute to between‐individual variation in fitness. 相似文献
In the German Wadden Sea there has been a remarkable decline in seagrass beds. It was the aim of this study to test whether
herbicide contamination could be a reason for this. Concentrations of triazine herbicides such as atrazine, simazine and terbutylazine
as well as phenylurea herbicides were measured in Wadden Sea sediments within or in the neighbourhood of seagrass meadows.
Sediments were thus used as a marker for medium-term contamination of the Wadden Sea. The respective concentrations were examined
in relation to the density and status of the seagrass meadows. Preliminary results show that there may be a connection between
seagrass decline and herbicide contamination in the parts of the Wadden Sea sampled. A comparison with other contamination
is also given.
Received: 11 January 1999 / Received in revised form: 1 December 1999 / Accepted: 8 December 1999 相似文献
We report two observations of adult male Antarctic fur seals, Arctocephalus gazella, preying on large octopods at subAntarctic Marion Island during July and August 2008. If Antarctic fur seals take cephalopods
opportunistically, as previously suggested, our observations may be a rare event representing such opportunistic predation. 相似文献
Type 2 diabetes mellitus (T2DM) is a multifactorial disease that requires multiple therapeutic strategies for its management. Bioactive peptides with multiple anti-diabetic targets are attractive therapeutic molecules. The present study was conducted to identify additional anti-diabetic targets of α-glucosidase inhibitory peptides, SVPA, SEPA, STYV, and STY. The α-glucosidase inhibitory activity of the peptides was in the order STYV?>?STY?>?SEPA?>?SVPA while molecular docking against human dipeptidyl peptidase IV (DPP-IV) showed that SVPA had the best binding affinity. In contrast, in vitro studies indicated that SEPA had a significantly higher (P?<?0.05) DPP-IV inhibitory activity (IC50?=?5.78?±?0.19 mM) than other peptides. SVPA and SEPA showed mixed inhibition pattern while STYV and STY were uncompetitive inhibitors of the enzyme. IPI (diprotin A), STYV and STY were not cytotoxic while SEPA displayed some cytotoxicity. In differentiated 3T3-L1 adipocytes, SVPA and STYV were found to induce a significant (P?<?0.05) decrease in intracytoplasmic lipid accumulation when added during the differentiation process while STY, GSH and IPI caused significant reduction (P?<?0.05) in the lipid accumulation when added after the differentiation. The SVPA, SEPA and STYV were better scavengers of methylglyoxal than STY but STYV had the best scavenging activities toward reactive oxygen species and nitric oxide. It was concluded that the four α-glucosidase inhibitory peptides including IPI have multiple targets against type T2DM but, overall, of the four peptides evaluated, STYV tends to have better potential for application as a multifunctional anti-diabetic peptide.
Opportunistic sightings of Antarctic fur seals Arctocephalus gazella and a leopard seal Hydrurga leptonyx at Gough Island (40°20′S, 09°54′W) in the South Atlantic Ocean represent the northernmost island records for vagrant Antarctic fur seals, and only the second for a vagrant leopard seal at Gough Island. Some ten different individual Antarctic fur seals were sighted on a single day, up to seven on a single beach. An overall total of 18 individuals were recorded over a 7-week period in October/November 2005, before the onset of the breeding (pupping) season of the resident population of Subantarctic fur seals Arctocephalus tropicalis. Most were immature, male and mostly in good condition (n = 11, 61%); one mature male and six putative females were also present. All had departed after 23 November, although only a fraction of the available beaches was searched. 相似文献
Although numerous studies have addressed the migration and dive behaviour of southern elephant seals (Mirounga leonina), questions remain about their habitat use in the marine environment. We report on the vertical use of the water column in
the species and the potential lifetime implications for southern elephant seals from Marion Island. Long-term mark-resight
data were used to complement vertical habitat use for 35 known individuals tagged with satellite-relay data loggers, resulting
in cumulative depth use extrapolated for each individual over its estimated lifespan. Seals spent on average 77.59% of their
lives diving at sea, 7.06% at the sea surface, and 15.35% hauled out on land. Some segregation was observed in maximum dive
depths and depth use between male and female animals—males evidently being physiologically more capable of exploiting increased
depths. Females and males spent 86.98 and 80.89% of their lives at sea, respectively. While at sea, all animals spent more
time between 300 and 400 m depth, than any other depth category. Males and females spent comparable percentages of their lifetimes
below 100 m depth (males: 65.54%; females: 68.92%), though males spent 8.98% of their lives at depths in excess of 700 m,
compared to females’ 1.84% at such depths. Adult males often performed benthic dives in excess of 2,000 m, including the deepest
known recorded dive of any air-breathing vertebrate (>2,133 m). Our results provide a close approximation of vertical habitat
use by southern elephant seals, extrapolated over their lifespans, and we discuss some physiological and developmental implications
of their variable depth use. 相似文献