Long-term breeding phenology shift in royal penguins

The Earth's climate is undergoing rapid warming, unprecedented in recent times, which is driving shifts in the distribution and phenology of many plants and animals. Quantifying changes in breeding phenology is important for understanding how populations respond to these changes. While data on shifts in phenology are common for Northern Hemisphere species (especially birds), there is a dearth of evidence from the Southern Hemisphere, and even fewer data available from the marine environment. Surface air temperatures at Macquarie Island have increased by 0.62°C during the 30-year study period (0.21°C decade(-1)) and royal penguins (Eudyptes schlegeli) commenced egg laying on average three days earlier in the 1990s than during the 1960s. This contrasts with other studies of Southern Ocean seabirds; five of nine species are now breeding on average 2.1 days later than during the 1950s. Despite the different direction of these trends, they can be explained by a single underlying mechanism: resource availability. There was a negative relationship between the Southern Annular Mode (SAM) and median laying date of royal penguins, such that low-productivity (low SAM) years delayed laying date. This accords with the observations of other seabird species from the Antarctic, where later laying dates were associated with lower sea ice and lower spring productivity. The unifying factor underpinning phenological trends in eastern Antarctica is therefore resource availability; as food becomes scarcer, birds breed later. These changes are not uniform across the region, however, with resource increases in the subantarctic and decreases in eastern Antarctica.     

Insulin-like hypoglycemic and immunological activities in honeybee royal jelly

An aqueous extract of royal jelly from Apis mellifera produced hypoglycemia when injected into larvae of Manduca sexta. Application of specific radioimmunoassay to the partially-purified extract showed that royal jelly contains several insulin-like peptides, the major immunoreactive component of which has an apparent mol. wt similar to that of bovine insulin. These results suggest the existence of a peptide in the honeybee having both biological and structural similarities to vertebrate insulin.     

Beak colouration as a possible sexual ornament in gentoo penguins: sexual dichromatism and relationship to body condition

Gentoo penguins (Pygoscelis papua) have conspicuous red beak spots, the function of which is currently unknown. We hypothesized that beak spots might be sexual ornaments and investigated sexual dichromatism, assortative mating and the possible relationship between beak spot colouration and body condition. Beak colouration was measured with a portable spectroradiometer in 19 breeding pairs of gentoo penguin. Body mass and body mass relative to structural body size were used as estimates of body condition. We found that beak spots were sexually dichromatic, as they were more UV in males and more violet in females, but males and females did not mate assortatively in relation to beak spot colouration. Body condition was strongly related to red colouration in males, with individuals in good condition having redder beaks and individuals in poor condition more orange beaks. The beaks of males in good condition were also brighter. Body condition was not significantly related to beak spot colouration in females, so females might show red beak spots because of genetic correlation with the male trait. These results suggest that the red colour of the beak spot has the potential to be a secondary sexual character in males. Interpretation of the sexual dichromatism in the UV colour will require further knowledge of the capability of gentoo penguins to discriminate small differences in UV wavelengths. In any case, experimental manipulation of beak colouration will be needed to ascertain the role of this trait.     

Colony self-shading facilitates Symbiodiniaceae cohabitation in a South Pacific coral community

The ecological success of tropical corals is regulated by symbiotic dinoflagellate algae (Symbiodiniaceae). Corals can associate with multiple Symbiodiniaceae species simultaneously, yet the conditions that permit Symbiodiniaceae cohabitation are not understood. We examined how corals self-shade their own tissues causing within-colony light gradients that drive Symbiodiniaceae photoacclimatory processes and positional genetic disparity. Paired light ‘exposed’ and ‘shaded’ samples from 20 coral species were collected from a shallow coral reef (Rarotonga, Cook Islands). Through active chlorophyll fluorometry, rapid light curves revealed that exposed Symbiodiniaceae exhibited 50% higher values in minimum saturating irradiances and demonstrated a shift towards preferential nonphotochemical quenching [1 – Q], consistent with higher overall light exposure. High-throughput or targeted DNA sequencing of ITS2 and psbA^ncr markers demonstrated that corals harboured distinct and/or differentially abundant Symbiodiniaceae ITS2 sequences (typically rare in relative abundance) or multiple ITS2 intragenomic variant profiles across shaded vs exposed regions. In Hydnophora cf. microconos, within-colony symbiont genetic disparity was positively correlated with the magnitude of difference in [1 – Q] utilisation. Together, these results suggest that within-colony light gradients produce distinct optical niches that enable symbiont cohabitation via photoadaptation, a phenomenon that is expected to increase the adaptive capacity of corals under future climates.

     

Gene-flow between niches facilitates local adaptation in sexual populations

In sexual populations, gene-flow between niches is predicted to have differential consequences on local adaptation contingent upon the nature of trade-offs underlying local adaptation. Sex retards local adaptation if antagonistic pleiotropy underlies trade-offs, but facilitates adaptation if mutation accumulation underlies trade-offs. We evaluate the effect of sex in heterogeneous environments by manipulating gene-flow between two niches in sexual and asexual populations using steady-state microcosm experiments with yeast. We find that only sex in the presence of gene-flow promotes simultaneous local adaptation to different niches, presumably as this exposes mutations neutrally accrued in alternate niches to selection. This finding aligns with work showing mutation accumulation underlies trade-offs to local adaptation in asexual microbes, and with inferences of divergence in the presence of gene-flow in natural sexual populations. This experiment shows that sex may be of benefit in heterogeneous environments, and thus helps explain why sex has been maintained more generally.     

Stable isotopes in southern rockhopper penguins: foraging areas and sexual differences in the non-breeding period

Southern rockhopper penguins (Eudyptes chrysocome chrysocome) have experienced severe population declines across their distribution area, potentially in response to bottom-up effects following elevated sea surface temperatures, changes in the food web and prey availability. We conducted stable isotope analysis to compare trophic levels and distribution patterns in the non-breeding period over three consecutive years, and between males and females, using egg membranes, blood cells and feathers of parent birds. Tissues representing the non-breeding season had lower ??¹³C values than prey sampled around the Falklands and red blood cells from breeding rockhopper penguins. In contrast, ??¹⁵N values were higher in red blood cells from the end of winter compared to those from the breeding season and compared to feathers. This indicated that rockhopper penguins left the Falkland Island area in the non-breeding season and foraged either around Burdwood Bank further south, or over the Patagonian Shelf. In winter, only males took more prey of higher trophic level than females. Inter-annual differences in isotopic values partly correlated with sea surface temperatures. However, as prey isotope samples were collected only in 1?year, inter-annual differences in penguin isotopic values may result from different foraging sites, different prey choice or different isotopic baseline values. Our study highlights the potential for stable isotope analyses to detect seasonal and gender-specific differences in foraging areas and trophic levels, while stressing the need for more sampling of isotopic baseline data.     

Medroxyprogesterone acetate acutely facilitates and sequentially inhibits sexual behavior in female rats

Medroxyprogesterone acetate (MPA), a synthetic progestin commonly used in contraception and hormone replacement therapy, appears to inhibit libido in women, but little is known about the mechanisms through which it may exert this effect. We compared the acute and sequential actions of MPA and natural progesterone (P4) on sexual behavior in female rats to test the hypothesis that MPA inhibits sexual behavior, at least in part, by acting as a potent progesterone receptor (PR) agonist. Ovariectomized females were placed in one of three dose groups (high, mid, or low), and each subject was tested under three different conditions (MPA, P4, and vehicle). The order of progestin treatment was balanced among subjects, and within each dose group equimolar quantities of MPA and P4 were administered. During each trial, females were injected with estradiol benzoate (EB, 4 mug) followed by one of three progestin treatments (MPA, P4, or vehicle) at +44 h, and behavioral testing at +48 h. On the next day, all females were given a standard 500-microg injection of P4 at +68 h and were tested again for sexual behavior at +72 h. On the first day of behavioral testing, both MPA and P4 induced a pronounced rise in receptive and proceptive behavior at the mid and high doses, but at the lowest dose MPA had a much greater effect in comparison to P4. On the second day of behavioral testing, MPA attenuated the expression of proceptive and receptive behavior at both the mid and high doses, whereas P4 only attenuated the expression of lordosis and only did so at the highest dose. These findings illustrate that MPA and P4 have a similar impact on sexual behavior in female rats and suggest that the inhibitory effects of MPA may be attributable, at least in part, to its potent effects at the progesterone receptor.     

Reproductive status effects of pair-housed male pigs on natural,agonistic and sexual behaviours

Boar rearing, which avoids pain and suffering caused by surgical castration, provides better performance, a greater deposition of muscle tissue and leaner carcasses and thus has beneficial effects on both animal welfare and the product. Some countries that do not slaughter boars must consider their boar taint and aggressive and sexual behaviours. Considering that pigs are housed in large groups, which may complicate the formation of social hierarchies and increase fighting and mounting behaviours, some studies have conducted research with reduced numbers of pigs per pen, but these behaviours continued to be observed. However, a study of the reproductive status of pair-housed male pigs has yet to be reported. The aim of this study was to determine whether the reproductive status of uncastrated, immunocastrated and surgically castrated pair-housed male pigs alters their natural, agonistic and sexual behaviours. A total of 48 male pigs from Agroceres PIC™ genetics were assigned to three groups: surgically castrated (barrows), immunocastrated and uncastrated (boars). Natural, aggressive and sexual behaviours of the pigs were assessed by direct observations during four periods of 12 h each (six, five and three weeks before slaughter and the slaughter week). The pigs were housed in pairs from the growing phase until slaughter. Animal behaviour was observed from the finishing phase to slaughter. Carcass lesions were assessed according to five different classes (one: no injury; two to five: severely injured). Overall, boars spent more time lying and less time eating and drinking than barrows. In total of all the periods (48 h), boars expressed more aggressive and sexual behaviours than barrows, whereas immunocastrated pigs displayed similar behaviours to boars, before and after the second vaccine dose. No differences in carcass lesions between treatments and no prevalence of carcasses with severe injuries were observed. In conclusion, the reproductive status of pair-housed male pigs did not change the natural behaviour of boars, immunocastrated pigs or barrows. The agonistic and sexual behaviours of boars and barrows remained unchanged. When housing pigs in pairs, immunocastrated pigs presented similar agonistic and sexual behaviours to boars before and after the second immunocastration vaccine dose. The use of pair-housed uncastrated male pigs has generated welfare benefits for these animals, as the number of carcasses with injuries did not differ from barrows and immunocastrated pigs.     

The agonistic and sexual functions of vocalizations of male brown-headed cowbirds,Molothrus ater

Functional analyses of three vocalizations of male brown-headed cowbirds, Molothrus ater, are presented and it is shown that two of these function as songs. Perched song (PS) is given by stationary birds and is used over short distances in male-male aggression and female courtship. The ‘flight whistle’ (FW) is a multisyllabic, usually pure tone, vocalization and the ‘single syllable flight call’ (SS) a monosyllabic pure tone. FWs and SSs are given occasionally by perched males and repetitively by flying males. Field playbacks of FWs showed that male cowbirds responded in the agonistic way most passerines respond to playback of conspecific song. Playbacks of the female's chatter call demonstrated that males of all three subspecies use FWs and SSs, but almost never PSs, to communicate with a female as they approach her. Thus FWs and SSs are used to communicate over long distances with both males and females. FWs are also used in one critical short-distance context as they are significantly more likely than PSs to be given just before copulations in nature, at least in our western study area. By contrast, studies of captive eastern cowbirds showed that PSs regularly precede copulations whereas FWs rarely do so. These different results for western and eastern birds may be an artefact of captivity and/or a result of geographical variation in behaviour.     

Oxytocin in the medial preoptic area facilitates male sexual behavior in the rat

Oxytocin (OT) is a versatile neuropeptide that is involved in a variety of mammalian behaviors, and its role in reproductive function and behavior has been well established. The majority of pharmacological studies of the effects of OT on male sexual behavior have focused on the paraventricular nucleus (PVN), ventral tegmental area (VTA), hippocampus, and amygdala. Less attention has been given to the medial preoptic area (MPOA), a major integrative site for male sexual behavior. The present study investigated the effects of intra-MPOA administration of OT and (d(CH2)51, Tyr(Me)2, Thr4, Orn8, Tyr-NH29)-vasotocin, an OT antagonist (OTA), on copulation in the male rat. The relationship between OT receptor (OTR) binding levels in the MPOA and sexual efficiency was also explored. Microinjection of OT into the MPOA facilitated copulation in sexually experienced male rats, whereas similar injections of an OTA inhibited certain aspects of copulation but had no significant effect on locomotor activity in an open field. Contrary to expectation, sexually efficient males had lower levels of OTR binding in the rostral MPOA compared to inefficient animals. The present data suggest that OT activity in the MPOA is not necessary for the expression of male sexual behavior but is sufficient to facilitate copulatory behaviors and improve sexual efficiency in sexually experienced male rats. These data also suggest that OTR activity in the MPOA stimulates anogenital investigation, facilitates the initiation of copulation, and plays a role in the sensitization effect of the first ejaculation on subsequent ejaculations.     

Long-term fasting and re-feeding in penguins

Spontaneous fasting during reproduction (sometimes with a full stomach) and moult is a major characteristic of the annual cycle of penguins. Long-term fasting (up to four months in male emperor penguins) is anticipated by the accumulation of fat (incubation fast) and of fat and protein (moult fast). During most of the incubation fast, birds rely almost entirely on lipids as an energy source, body proteins being spared. However, below a critical (but non-total) fat store depletion, marked behavioural, metabolic, and endocrine changes occur. Spontaneous locomotor activity increases and the egg is transitorily left unincubated for increasingly long periods, until its definitive abandon and the bird departs to re-feed at sea. These changes are thought to be activated by an endogenous re-feeding signal triggered before lethal energy depletion. An increase in body protein catabolism in the face of a reduction in lipid availability and utilisation, and an increase in circulating corticosterone vs. a decrease in plasma prolactin, are likely to be major metabolic and hormonal components of this signal. The survival and rapid restoration of energy stores in birds having departed to re-feed at a stage of near total lipid depletion demonstrates the effectiveness of the re-feeding signal. Penguins, and possibly other seabirds, are therefore appropriate animal models for understanding the long-term interactions between body energy reserves and fasting, breeding and feeding physiology and behaviour.     

A single injection of 17 beta-estradiol facilitates sexual behavior in castrated male mice

Sexual behavior was assessed in castrated adult CD-1 male mice given exogenous steroids under various treatment regimens. Castrated mice maintained on 20 μg testosterone (T) daily for 1 week, but given 250 μg testosterone propionate (TP) on the day of testing showed higher levels of copulatory activity than intact mice or the males receiving an additional dose of 20 μg T on the test day, although plasma testosterone levels were not different at the time of behavioral testing. Castrated males given 50, 125, or 250 μg TP for 1 week including the day of testing showed higher levels of sexual behavior than males receiving the same doses of TP only once, on the test day. A single injection of 17β-estradiol (E₂) completely restored the male copulatory pattern, including ejaculation, in castrated mice under every condition examined. Testosterone and dihydrotestosterone (DHT) were less effective than E₂, as was the combination of E₂ and DHT. The relative efficacy of a single dose of T, DHT, and E₂ plus DHT was dependent upon factors such as the delay between steroid administration and testing, as well as whether or not the castrated mice received androgen replacement prior to testing. Estradiol benzoate (E₂B) was not capable of restoring sexual behavior in castrated mice in this study. The comparison of results obtained with TP, T, E₂, and E₂B suggests that an appreciable, but not necessarily sustained, elevation of E₂ levels in the brain may be critical in the facilitation of male copulatory behavior in mice.     

A comparison of the LH-releasing activities of LH-RH and its agonistic analogue buserelin in the ovariectomized rat

LH-RH and the potent agonistic analogue (D-Ser(But)6-des-Gly10)-LH-RH(1-9)-ethylamide (HOE-766 or buserelin) were at several doses either infused or injected intravenously in 5-weeks-ovariectomized rats, which had been treated with either 3 micrograms estradiol-benzoate (EB) or with oil, 24 h previously. Blood samples for assay of LH were taken during the subsequent 24 h. Pituitary glands were removed at the end of the experiments. Buserelin, when infused, was slightly more effective than LH-RH on releasing LH. When injected, however, buserelin was at the higher dose ranges increasingly more effective as an LH-releasing agent than LH-RH. EB-treatment increased the LH response of the pituitary gland to both peptides in an identical way. It was concluded that buserelin derives its high potency not from its intrinsic LH-releasing activity, which is only slightly greater than that of LH-RH, but from a longer duration of action.     

The effect of investigators on the breeding success of royal,Eudyptes schlegeli,and rockhopper penguins,E. chrysocome,at Macquarie Island

The impact on reproductive success of investigators studying the breeding biology of royal and rockhopper penguins was assessed. Control and experimental transects were established in a colony of each species and the number of active nests, from egg laying to creche stage, were compared. Experimental nests were those used in breeding biology work, where birds were measured and banded, and nest checks were carried out at least once per week. Control nests were in equivalent locations but birds were not handled, and no contact was made with the nests once breeding had begun. There were no significant differences in the number of active nests between the control and experimental transects (and, therefore, breeding success) in either species. It is concluded that, provided care is taken when working with these species, no impacts on the short-term (up to creche stage, in one breeding season) breeding success of these populations will occur.     

Hypoxemic and ischemic tolerance in emperor penguins

The presence of 7-O-acyl okadaic acid (OA) esters was studied by LC–MS in the digestive glands of blue mussel (Mytilus galloprovincialis) and common cockle (Cerastoderma edule) from Albufeira lagoon, located 20 km south of Lisbon. The profile of free and total fatty acids (FA) was analysed using a similar LC separation with a reversed phase C8 column and mass spectrometry detection. In mussel the free FA profile was reflected in the FA esterified to OA, being palmitic acid for instance the most abundant in both cases. In cockle, 7-O-acyl esters with palmitic acid were almost absent and esters with a C16:0 isomer were dominant, followed by esters with C15:1 and C15:0. The cockle free FA profile was similar to mussel, and in accordance with literature findings in bivalves. After hydrolysis, a major difference in the FA profile occurred in both species, presenting a high percentage of a C16:0 isomer. The isomer found in general lipids and bound to OA seemed to be related, presenting similar relative retention times (RRT) to C16:0, differing from expected RRT of monomethyl-branched isomers (iso- or anteiso-). A tentative identification was made with the multimethyl-branched isoprenoid, 4,8,12-trimethyltridecanoic acid (TMTD). TMTD is a product of phytol degradation. This was also suspected when the proportion of this compound in relation to palmitic acid was reduced in vivo in mussels fed a chlorophyll-free diet. Extensive esterification of OA by, among others, phytol-degrading bacteria is discussed as a plausible hypothesis in cockle, but not in mussel, due to the relatively high specific proportion of odd-numbered and branched FA.     

Neonatal exposure to estradiol decreases hypothalamic allopregnanolone concentrations and alters agonistic and sexual but not affective behavior in adult female rats

Exposure of developing female rats to estradiol during the perinatal period induced long-lasting dysregulation of gonadal axis and decreased cerebrocortical and plasma concentrations of allopregnanolone. We have now examined the effects of neonatal estradiol administration in female rats on hypothalamic allopregnanolone concentrations and on exploratory, affective, agonistic and sexual behaviors as well as social learning. A single administration of β-estradiol 3-benzoate (EB, 10 μg) on the day of birth resulted in a delay of vaginal opening, acyclicity and ovarian failure. These alterations were associated with a significant decrease in the concentrations of allopregnanolone in the hypothalamus at 21 and 60 days, but not at 7 days, after birth. Neonatal administration of EB also increased agonistic behaviors in adult rats, such as dominant behaviors and following of an ovariectomized intruder, while living attacks unaffected. EB-treated rats showed also an increase in anogenital investigation, associated with a drastic reduction in spontaneous and induced female sexual behaviors (receptivity and proceptivity). In contrast, neonatal administration of EB did not affect locomotor activity, anxiety- and mood-related behaviors, the social transmission of flavor preferences, and seizures sensitivity. These effects of estradiol suggest that it plays a major role in regulation of both the abundance of allopregnanolone and the expression of agonistic and sexual behaviors, while failing to influence affective behaviors and social learning. Thus, the pronounced and persistent decrease in hypothalamic allopregnanolone concentration may be related to the manifestation of agonistic and sexual behaviors.