Although cooperative social interactions within species are considered an important driver of evolutionary change, few studies have experimentally demonstrated that they cause adaptive evolution. ...Here we address this problem by studying the burying beetle Nicrophorus vespilloides. In this species, parents and larvae work together to obtain nourishment for larvae from the carrion breeding resource: parents feed larvae and larvae also self-feed. We established experimentally evolving populations in which we varied the assistance that parents provided for their offspring and investigated how offspring evolved in response. We show that in populations where parents predictably supplied more care, larval mandibles evolved to be smaller in relation to larval mass, and larvae were correspondingly less self-sufficient. Previous work has shown that antagonistic social interactions can generate escalating evolutionary arms races. Our study shows that cooperative interactions can yield the opposite evolutionary outcome: when one party invests more, the other evolves to invest less.
Parental care has been shown to reduce the magnitude of inbreeding depression in some species with facultative care. However, parents often vary in the quality or amount of care they provide to their ...offspring, and it is less clear whether this variation also impacts the magnitude of inbreeding depression. Here, we tested whether age‐related changes in parental care modulate the expression of inbreeding depression in the burying beetle, Nicrophorus orbicollis. Consistent with previous studies, we found that older parents produced larger broods of offspring than younger parents without sacrificing mean larval mass. Inbreeding depression was evident in several fitness‐related traits: brood size at dispersal, the proportion of the brood that survived to eclosion, and mean age at death were all reduced in inbred broods compared with outbred broods. Surprisingly, inbred offspring were heavier at dispersal than outbred offspring. This was likely due to reduced sibling competition in inbred broods. Despite evidence for age‐related changes in parental investment and the existence of inbreeding depression, there was no evidence that an interaction between the two influenced any of the traits we measured. Our results suggest that age‐related changes in parental care may be too slight to influence the expression of inbreeding depression.
Here, we tested whether age related changes in parental care modulate the expression of inbreeding depression in the burying beetle, Nicrophorus orbicollis. Despite evidence for age related changes in parental investment and the existence of inbreeding depression, there was no evidence that an interaction between the two influenced any of the traits we measured. Our results suggest that age‐related changes in parental care may be too slight to influence the expression of inbreeding depression.
In organisms that provision young between fertilization and birth, mothers and their developing embryos are expected to be in conflict over embryonic growth. In mammalian embryos, the expression of ...Insulin-like growth factor II (IGF2) plays a key role in maternal-fetal interactions and is thought to be a focus of maternal-fetal conflict. Recent studies have suggested that IGF2 is also a focus of maternal-fetal conflict in placental fish in the family Poeciliidae. However, whether the expression of IGF2 influences offspring size, the trait over which mothers and embryos are likely to be in conflict, has not been assessed in a poeciliid. We tested whether embryonic IGF2 expression varied among four populations of a placental poeciliid that display large and consistent differences in offspring size at birth. We found that IGF2 expression varied significantly among embryonic stages with expression being 50% higher in early stage embryos than late stage embryos. There were no significant differences among populations in IGF2 expression; small differences in expression between population pairs with different offspring sizes were comparable in magnitude to those between population pairs with the same offspring sizes. Our results indicate that variation in IGF2 transcript abundance does not contribute to differences in offspring size among H. formosa populations.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The mating system is expected to have an important influence on the evolution of mating and parenting behaviors. Although many studies have used experimental evolution to examine how mating behaviors ...evolve under different mating systems, this approach has seldom been used to study the evolution of parental care. We used experimental evolution to test whether adaptation to different mating systems involves changes in mating and parenting behaviors in populations of the burying beetle, Nicrophorus vespilloides. We maintained populations under monogamy or promiscuity for six generations. This manipulation had an immediate impact on reproductive performance and adult survival. Compared to monogamy, promiscuity reduced brood size and adult (particularly male) survival during breeding. After six generations of experimental evolution, there was no divergence between monogamous and promiscuous populations in mating behaviors. Parents from the promiscuous populations (especially males) displayed less care than parents from the monogamous populations. Our results are consistent with the hypothesis that male care will increase with the certainty of paternity. However, it appears that this change is not associated with a concurrent change in mating behaviors.
We used experimental evolution to test whether adaptation to monogamy involved changes in mating and parenting behaviors in the burying beetle, Nicrophorus vespilloides. We found that males from monogamous and promiscuous populations did not differ in mating behaviors. However, males from monogamous populations were more attentive parents than males from promiscuous populations.
We used phenotypic manipulation experiments to test whether stridulation is necessary for effective parental care in two burying beetle species (Nicrophorus orbicollis and N. vespilloides).
Our ...phenotypic manipulation rendered the both species silent; however, it had no detectable impact on parental performance in either species.
Our results suggest that stridulation is unimportant for parental care in at least two Nicrophorus species, casting doubt upon a long‐assumed function of stridulation in the genus.
1. Communication among family members is often essential for navigating the social and trophic interactions that arise during parental care. In insects, this communication is often accomplished via pheromonal signals. However, some insects also produce acoustic signals (stridulations) during parental care.
2. Burying beetles (Nicrophorus spp) audibly stridulate during mating and parental care and several studies have suggested that stridulation is an important form of communication between family members. Experimental studies have generally supported a role of stridulation in Nicrophorus parental care: preventing stridulation or changing the vibrational properties of stridulation generally reduces parental performance. However, some of these previous experiments are difficult to interpret and the importance of this form of communication in burying beetles is still unclear.
3. Here we describe experiments involving two Nicrophorus species (N. vespilloides and N. orbicollis) in which we used a minimally invasive phenotypic manipulation to test whether stridulation is necessary for effective parental care. Our phenotypic manipulation rendered the both species silent; however, it had no detectable impact on parental performance in either species.
4. Our results suggest that stridulation does not play an important role in mating or the coordination of parental care in at least two Nicrophorus species, casting doubt upon a long‐assumed function of stridulation in the genus.
Introduction:
Idiopathic pulmonary fibrosis (IPF) patients admitted to the ICU with acute respiratory failure (ARF) are known to have a poor prognosis. However, the majority of the studies published ...to date are older and had small sample sizes. Given the advances in ICU care since the publication of these studies, we sought to reevaluate the outcomes and risk factors associated with mortality in these patients.
Methods:
Retrospective study using a large multi-center ICU database. We identified 411 unique patients with IPF admitted with ARF between 2014-2015.
Results:
Of all IPF patients admitted to the ICU with ARF, 81.3% required mechanical ventilation (MV): 48.9% invasive and 32.4% non-invasive alone. The hospital mortality rate was 34.5% for all patients; 48.8% in patients requiring invasive MV, 21.8% in those requiring non-invasive MV and 19.5% with no MV. In multiple regression analyses, age, APACHE score, invasive MV, and hyponatremia at admission were associated with increased mortality whereas post-op status was associated with lower mortality. In patients requiring invasive MV, baseline PaO2/FiO2 ratio was also predictive of mortality. Non-pulmonary organ failures were present in less than 20% of the patients.
Conclusions:
Although the overall mortality rate for IPF patients admitted to the ICU with ARF has improved, the mortality rates for patients requiring invasive MV remains high at approximately 50%. Older age, high APACHE score, and low baseline PaO2/FiO2 ratio are factors predictive of increased mortality in this population.
Inbreeding depression occurs when individuals who are closely related mate and produce offspring with reduced fitness. Although inbreeding depression is a genetic phenomenon, the magnitude of ...inbreeding depression can be influenced by environmental conditions and parental effects. In this study, we tested whether size‐based parental effects influence the magnitude of inbreeding depression in an insect with elaborate and obligate parental care (the burying beetle, Nicrophorus orbicollis). We found that larger parents produced larger offspring. However, larval mass was also influenced by the interaction between parental body size and larval inbreeding status: when parents were small, inbred larvae were smaller than outbred larvae, but when parents were large this pattern was reversed. In contrast, survival from larval dispersal to adult emergence showed inbreeding depression that was unaffected by parental body size. Our results suggest that size‐based parental effects can generate variation in the magnitude of inbreeding depression. Further work is needed to dissect the mechanisms through which this might occur and to better understand why parental size influences inbreeding depression in some traits but not others.
We tested whether parental body size influenced the magnitude of inbreeding depression in an insect with obligate parental care (Nicrophorus orbicollis). We found that when parents were small, inbred larvae were smaller than outbred larvae. This pattern was reversed with parents who were large. In contrast, survival to eclosion displayed inbreeding depression that was insensitive to parental size.
Asymmetric sibling competition arises when siblings with different competitive abilities share a limited resource. Such competition occurs in species with postnatal parental care and may also occur ...when mothers provision embryos between fertilization and birth (matrotrophy). We hypothesized that the combination of matrotrophy and the simultaneous provisioning of embryos in different stages of development (superfetation) leads to asymmetric competition between sibling embryos. Moreover, we expect the intensity of this competition to increase with the level of superfetation as high levels of superfetation result in greater temporal overlap between broods. This hypothesis predicts that offspring from early broods, which predominantly compete with less-developed siblings, will be larger at birth than offspring from later broods, which experience competition from more and less-developed siblings. Data on offspring size at birth from two populations of the highly matrotrophic fish, Heterandria formosa, and similar studies of poeciliid fish spanning a range of life histories are consistent with our hypothesis. Together these results suggest that sibling competition is a direct consequence of the evolution of matrotrophy and superfetation in poeciliid fish.
The evolution of matrotrophy introduces the potential for genomic conflicts between mothers and embryos. These conflicts are hypothesized to accelerate the evolution of reproductive isolation and to ...influence the evolution of life-history traits, reproductive structures, and genomic imprinting. These hypotheses assume offspring can influence the amount of maternal investment they receive and that there is a trade-off between maternal investment into individual offspring and maternal survival or fecundity. We used field data and laboratory crosses to test whether these assumptions are met in the matrotrophic poeciliid fish Heterandria formosa. Comparisons of life histories between two natural populations demonstrated a trade-off between the level of maternal investment into individual embryos and maternal fecundity. Laboratory crosses between individuals from these populations revealed that offspring genotype exerts an influence on the level of maternal investment and affects maternal fecundity through higher rates of embryo abortion and lower numbers of full-term offspring. Our results show that the prerequisites for parent-offspring conflict to be a potent evolutionary force in poeciliid fish are present in H. formosa. However, determining whether this conflict has shaped maternal investment in nature will require disentangling any effects of conflict from those of several ecological factors that are themselves correlated with the expected intensity of conflict.
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