The evolution of endothermy in vertebrates is a major research topic in recent decades that has been tackled by a myriad of research disciplines including paleontology, anatomy, physiology, ...evolutionary and developmental biology. The ability of most mammals to maintain a relatively constant and high body temperature is considered a key adaptation, enabling them to successfully colonize new habitats and harsh environments. It has been proposed that in mammals the anterior nasal cavity, which houses the maxilloturbinal, plays a pivotal role in body temperature maintenance, via a bony system supporting an epithelium involved in heat and moisture conservation. The presence and the relative size of the maxilloturbinal has been proposed to reflect the endothermic conditions and basal metabolic rate in extinct vertebrates. We show that there is no evidence to relate the origin of endothermy and the development of some turbinal bones by using a comprehensive dataset of µCT-derived maxilloturbinals spanning most mammalian orders. Indeed, we demonstrate that neither corrected basal metabolic rate nor body temperature significantly correlate with the relative surface area of the maxilloturbinal. Instead, we identify important variations in the relative surface area, morpho-anatomy, and complexity of the maxilloturbinal across the mammalian phylogeny and species ecology.
A strict underground style of life is one of the greatest challenges for mammals partly due to the high energetic cost of obtaining food by digging through a mechanically resistant substrate. Any ...energy saving adaptation, for example the effect of social thermoregulation, is thus very important for subterranean mammals. It has also been suggested that social mammals may suffer from “isolation stress” if measured alone, because the presence of other family member(s) may decrease the stress levels and thus their metabolic rates. This phenomenon known as a socio-physiological effect should be conspicuous when the metabolism of huddling individuals is measured within a species΄ thermoneutral zone (TNZ), where no energetic costs for body warming or cooling exist. In our study, we measured the resting metabolic rates of a social species of African mole-rat, the Mashona mole-rat (Fukomys darlingi), in individuals, pairs and groups of three to eight individuals. Measurements were carried out at ambient temperature below the species’ TNZ (20 °C) to test the effect of social thermoregulation and at a temperature within the species’ TNZ (30 °C) to test the socio-physiological effect. In pairs, the Mashona mole-rat saved 25% of its individual energetic expenses at the temperature below the TNZ. With increasing group size, energetic savings rose up to four animals, but no savings were found in larger groups. At the temperature within the TNZ, mole-rats saved 10% of individual energetic expenses in pairs, but the difference was not significant. Also, no energetic savings were found in larger groups within the TNZ. Our results on thermoregulatory savings in the TNZ are in contrast with extremely high energetic savings found by other authors in different mole-rat species.
•Energetic savings of huddling were studied in the African mole-rat Fukomys darlingi.•Mole-rats in pairs saved 25% of their energy expense due to social thermoregulation.•In larger groups the influence of social thermoregulation rose up to group of four.•There were no energetic savings at the Ta within the TNZ.•No savings in the TNZ indicate the absence of a socio-physiological effect.
Bite force is an ecologically relevant performance trait that has been measured to better understand the adaptations to diet and habitat use. Moreover, bite force is relevant in understanding ...reproductive success, as well as inter‐ and intraspecific competition.
African mole‐rats (Bathyergidae, Rodentia) are a unique clade of mammals that use different digging strategies, show different types of social organization and occur in ecologically diverse savanna habitats in sub‐Saharan Africa. Whereas previous studies have suggested these animals have exceptionally high bite forces, the ecological and other proximate and ultimate drivers of variation in bite force in the group remain unstudied.
In the present study we measured in vivo bite force of 394 adult specimens from 10 African mole‐rat species including all genera within the family.
Our results show that in African mole‐rats digging mode is a major driver of variation in bite force, with chisel‐tooth diggers being stronger biters than scratch diggers. Moreover, species living in habitats characterized by low and irregular precipitation patterns and in soils with a high content of coarse particles have a higher bite force than species occupying habitats with a regular rainfall pattern and fine soil types.
This suggests that bite force in bathyergids has evolved in concert with rainfall and soil characteristics of different savanna habitats, which have contributed to the successful radiation of these subterranean mammals across sub‐Saharan Africa.
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Abstrakte
Bytkrag is n ekologies relevante prestasie eienskap wat gemeet is om die aanpassings van dieet en gebruik van habitat beter te verstaan. Bytkrag is ook verder relevant om die reproduktiewe sukses van inter‐ en intra spesifieke kompetisie te verstaan.
Afrika vaalmolle (Bathyergidae, Rodentia) is ń unieke klade van soogdiere wat verskillende grawe tegnieke gebruik, verskillende tipe sosiale organisasie wys en voorkom in ekologies verskillende savanne habitatte in Afrika suid van die Saharah. Vorige studies het voorgestel dat hierdie diere uitsonderlike hoë bytkrag het, maar die variasie in bytkrag, veroorsaak deur ekologiese en ander dryfkragte, is nog ongebestudeer.
In die huidige studie het ons in vivo bytkrag van byna 400 volwasse eksemplare van tien Afrika vaalmol spesies, insluitend alle genera in die familie, bestudeer.
Ons resultate wys dat Afrika vaalmolle se wyse van grawe n groot invloed het op die variasie in bytkrag, waar beitel gevormde tand grawers sterker byters is as krap grawers. Bowendien het spesies wat in habitatte lewe waar lae en onreëlmatige reëns voorkom en waar grond ń hoë inhoud van growwe partikels het, ń hoër bytkrag het as spesies wat in habitatte voorkom met reëlmatige reënval patrone en fyner grondtipes.
Hieruit word afgely dat bytkrag in bathyergids gesamentlik ontwikkel het met reënval en grond eienskappe van verskillende savana habitatte, wat weer bygedra het tot die suksessvolle verspreiding van hierdie ondergrondse soogdiere oor sub‐Saharah Afrika.
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The European spruce bark beetle (Ips typographus) is a highly destructive pest of spruce monocultures. Adult spruce bark beetles are well-adapted to survive over winter however, the ability of ...sub-adult stages to overwinter has not been clearly established. The increase in average temperature recorded over the last three decades has resulted in an increase in voltinism by one generation, but due to insufficient time the last generation may not complete its development. It is crucial to investigate the survival and development of sub-adult stages at low temperatures in order to predict the effect of increased voltinism on the population dynamics of this species. We measured the development and survival of larvae and pupae (over 12 weeks) in logs kept at winter temperatures outdoors (in shade and exposed to sunlight) and in the laboratory (at 0 and 5°C), with 10°C as a control, at which normal development was expected. Overall, findings revealed that development continued at low temperatures, although it was slower than at high temperatures. Importantly, after 12 weeks significant numbers of spruce bark beetles were present, including newly emerged adults. We demonstrate, for the first time, that sub-adult spruce bark beetles can mature over winter and the percentage survival was significant, indicating that some of the beetles that did not complete their development before the onset of winter can complete their development during winter and potentially adversely affect forests and pose problems for their management.
A novel method was used to study dispersal in the spruce bark beetle, Ips typographus (L.), under epidemic conditions (rapidly increasing population density) in the Sumava National Park. Infested ...spruce logs were coated with a fine fluorescent powder and the passively marked emerging beetles were captured in pheromone baited traps located at various distances from these logs. The number of marked beetles captured decreased exponentially with increasing distance from the release point. The sex ratio of the bark beetles was more female biased the further they were recaptured from the logs, being 57% and 60% at distances of up to 50 and 100 m, respectively. The maximum distance flown by a marked beetle recorded in this experiment was 1094 m. A model fitted to the data on dispersal indicates that 10% of the spruce bark beetles dispersed over distances of 55 m and 4 m in spring (overwintered parental generation) and summer (first filial generation), respectively. Differences between spring and summer swarming are briefly discussed.
Abstract Searching for food by extensive digging is one of the most important aspects of life of subterranean rodents. We studied the effect of extrinsic (substrate quality) and intrinsic factors ...(sex and body mass) upon the cost of burrowing, expressed as digging metabolic rate (DMR) in two African mole-rat species (Bathyergidae, Rodentia) with distinct social structures. The sexually dimorphic giant mole-rat ( Fukomys mechowii ) is a highly social species, whereas the almost monomorphic silvery mole-rat ( Heliophobius argenteocinereus ) is a solitary bathyergid. Burrowing in F. mechowii was more costly (DMR was greater) than in H. argenteocinereus , but there was no difference in burrowing speed between both species. DMR within a particular species was dependent upon body mass, but independent of sex. Different substrate quality had no effect upon DMR in either species, yet it affected burrowing speed. We conclude that less effective digging in F. mechowii can be compensated by the joint workforce of other family members. Alternatively, H. argenteocinereus , being a more effective digger, can afford a solitary way of life.
•Bark beetle outbreaks often span forests including managed and unmanaged stands.•We find preferential bark beetle dispersal from managed into unmanaged stands.•A strong ecological pressure imposed ...by management strategies may explain this pattern.
Bark beetle outbreaks have a devastating effect on economically important forests worldwide, thus requiring extensive application of management control strategies. The presence of unmanaged protected areas in close proximity to managed forests can instigate concerns that bark beetle infestations may spread from unmanaged into managed stands. We studied the impact of differential management of forest stands on the dispersal dynamics of the European spruce bark beetle, Ips typographus, making use of inferential population genetics on mitochondrial and nuclear genomes. Bayesian inferences of migration rates and a most parsimonious dispersal tree show that outgoing gene flow was consistently higher from managed to unmanaged areas. Reason for that is likely the thorough removal of potential breeding material in managed forests and thus the dispersal of the base stock beetles from these areas to unmanaged areas where breeding material is available. Our study suggests that the potential threat posed by unmanaged to managed forests in regard to I. typographus infestation needs to be carefully re-considered.
In this study, the current distribution of ghost ant (GA) in Europe is reviewed. Furthermore, the authors report the first record of GA in the Czech Republic, where a large colony of GA was ...discovered in a block of flats in Ceske Budejovice in 2014, and present a case study of its eradication. The revised distribution of GA shows that despite previous concerns about the threats posed by this new pest only three other European countries (including Czech Republic) reported the presence of this species after 2009. Abundance of workers was monitored in two flats in an infested building using traps baited with yolk-honey and GA were subsequently eradicated with imidacloprid. The pre-treatment revealed abundances that ranged up to 524 workers per trap. Despite the initial success of the treatment, monitoring of the building a year later revealed it was still infested with GA and in a similar rate. The authors suggest alternative methods of eradicating GA in the temperate zone based on studies carried out in the tropics.
Reproduction is an energetically expensive process that supposedly impairs somatic integrity in the long term, because resources are limited and have to be allocated between reproduction and somatic ...maintenance, as predicted by the life history trade-off model. The consequence of reduced investment in somatic maintenance is a gradual deterioration of function, i.e. senescence. However, this classical trade-off model gets challenged by an increasing number of contradicting studies. Here we report about an animal model, which adds more complexity to the ongoing debate. Ansell's mole-rats are long-lived social subterranean rodents with only the founder pair reproducing, while most of their offspring remain in the parental burrow system and do not breed. Despite of a clear reproductive trade-off, breeders live up to twice as long as non-breeders, a unique feature amongst mammals.
We investigated mass-specific resting metabolic rates (msRMR) of breeders and non-breeders to gain information about the physiological basis underlying the reproduction-associated longevity in Ansell's mole-rats. We assessed the thermoneutral zone (TNZ) for breeders and non-breeders separately by means of indirect calorimetry. We applied generalized linear mixed-effects models for repeated measurements using the msRMR in the respective TNZs.
TNZ differed between reproductive and non-reproductive Ansell's mole-rats. Contrary to classical aging models, the shorter-lived non-breeders had significantly lower msRMR within the thermoneutral zone compared to breeders.
This is the first study reporting a positive correlation between msRMR and lifespan based on reproductive status. Our finding contradicts common aging theories, but supports recently introduced models which do not necessarily link reproductive trade-offs to lifespan reduction.
1. In various insect and spiders, males offer nuptial food gifts to females during copulation that enhance male fitness either directly through their effects on male fertilisation success or ...indirectly through the nutritional benefits delivering for females. However, the physiological costs of producing these gifts remain largely unexplored.
2. We examined energetic costs of holding nuptial gifts in the gift‐giving spider, Pisaura mirabilis, using stop‐flow respirometry.
3. Males exhibited 37% higher metabolic rates when holding a nuptial gift than when they do not have one.
4. Our findings suggest the existence of metabolic costs associated with holding a nuptial gift for males. This confirm that male condition is particularly relevant for gift‐giving and may explain the evolution of male deception for cheaper nuptial gifts.
We examined energetic costs of carrying nuptial gifts in the gift‐giving spider, Pisaura mirabilis, using stop‐flow respirometry.
Males exhibited 37% higher metabolic rates when carrying a nuptial gift than when they do not have one.
Our findings suggest the existence of metabolic costs associated with carrying a nuptial gift for males.
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