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The enlarged brains of homeotherms bring behavioural advantages, but also incur high energy expenditures. The ‘expensive brain’ (EB) hypothesis posits that the energetic costs of the enlarged brain and the resulting increased cognitive abilities (CA) were met by either increased energy turnover or reduced allocation to other expensive organs, such as the gut. We tested the EB hypothesis by analysing correlated responses to selection in an experimental evolution model system, which comprises line types of laboratory mice selected for high or low basal metabolic rate (BMR), maximum (VO2max) metabolic rates and random-bred (unselected) lines. The traits are implicated in the evolution of homeothermy, having been pre-requisites for the encephalization and exceptional CA of mammals, including humans. High-BMR mice had bigger guts, but not brains, than mice of other line types. Yet, they were superior in the cognitive tasks carried out in both reward and avoidance learning contexts and had higher neuronal plasticity (indexed as the long-term potentiation) than their counterparts. Our data indicate that the evolutionary increase of CA in mammals was initially associated with increased BMR and brain plasticity. It was also fuelled by an enlarged gut, which was not traded off for brain size.

SEB Annual Conference 2022

Brain size, gut size and cognitive abilities: the energy trade-offs tested in artificial selection experiment

Discover the art of creating extraordinary science at SEB’s Annual Conference at Le Corum Conference Center     in Montpellier, France from 5 to  8 July 2022.

SEB’s Annual Conference is celebrated for creating the perfect composition of research, new discoveries and collaborative connections. Be creative and innovative by exchanging ideas and knowledge with masters of biology from all over the world.

2022 will find over 1500 experimental biologists from across the globe converging on the third-largest French city near the Mediterranean coast and the fastest-growing city in the country over the past 25 years.
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Please register for the conference by clicking on this link:

https://www.sebiology.org/events/seb-annual-conference-2022/registration.html

The site will be open for registered participants closer to the event.

2022 will find over 1500 experimental biologists from across the globe converging on the third-largest French city near the Mediterranean coast and the fastest-growing city in the country over the past 25 years - Montpellier, France

poster

Berghia stephanieae is a small nudibranch of the aeolid family, known to feed voraciously on the anemone Aiptasia pallida, a common pest in tropical aquaria. Berghia is sold in the aquarium trade for anemone density control. Though well documented in the aquarium context, studies on Berghia-Aipatsia interactions in the natural environment are more scarce. Being a specialised predator (as are most nudibranchs) that feeds exclusively on A. pallida, it is unclear how both species can coexist in the natural environment without B. stephanieae causing local extirpation of its prey. Building on the discovery of kleptopredation in 2017 in the aeolid nudibranch Cratena peregrina, the current research investigates the possibility of this mechanism being used by other nudibranch species, here B. stephanieae. C. peregrina is a highly specialised predator known to feed exclusively on hydroid E. racemosum polyp, yet half of their diet was found to consist of planktonic prey acquired through kleptopredation. The current research investigates the feeding strategy of B. stephanieae, and the possibility of kleptopredation. B. stephanieae were reared and fed in the laboratory with either kleptopredation treatment (recently-fed anemones) or control diet treatment (unfed anemones). Their physiology was studied over time under each treatment conditions, to assess the possible benefits of kleptopredation on the energy budget. Preliminary results suggest kleptopredation is exhibited by Berghia stephanieae. Growth, spawning, and respiration measurements show that this feeding strategy could provide energetic benefit to the nudibranch predator by allowing more energy to be invested in growth and reproduction. 




Physiology and feeding strategies of Berghia stephanieae (Nudibranchia: Aeolidiodea)

The 65 million year acoustic arms race between moths and bats has lead to the evolution of numerous different defence strategies amongst moths against bat echolocation.  Some moths have evolved passive defences such as ultrasound absorbing scales, which diminish the strength of a moth generated echo returning to a bat.  The scales work by resonant mechanisms and are much smaller than the wavelength of the sound which they absorb. This unique architecture opens avenues for bioinspired sound insulation solution that are much smaller than current technical sound absorbers. Previous works have looked at sound absorption by moth scales in free space, but to determine their effectiveness as a sound insulating solution for buildings, their performance must be measured when resting on a hard substrate. Here, we measure the potential for moth wings to act as a sound absorbing surface coating for acoustically reflective substrates. Moth wings were found to be efficient sound absorbers, reducing reflection from an acoustically hard surface by up to 87% despite a thickness to wavelength ratio of up to 1/50 at the lowest frequency tested (20 kHz). Remarkably, after removal of the scales from the dorsal surface the wing’s orientation on the surface changed its absorptive performance: absorption remains high when the bald wing membrane faces the sound but breaks down almost completely in the reverse orientation. The finding that moth wings can act as a sound absorbing surface opens the door to the creation of biomimetic light-weight noise mitigation materials.

Towards moth wing inspired sound absorbing materials

The increasing frequency and intensity of marine heatwaves (MHW) and simultaneous water deoxygenation (i.e., hypoxia) resulting from anthropogenic climate change is increasingly affecting marine organisms worldwide. These stressors occur throughout the year, and marine organisms may be differentially vulnerable to these events across seasons. While most climate change projections highlight summer maximum temperatures as the greatest threat to coral reef organisms, this prediction has never been tested. After characterizing local MHWs in Kāneʻohe Bay, HI, we compared the capacity of representative Hawaiian reef fish of commercial importance—the convict tang (Acanthurus triostegus; manini) —to tolerate the combined effects of acute thermal stress and reduced oxygen availability that occur during MHWs between seasons. While marine heatwaves did not significantly differ in heating rate, duration, or warming anomaly (i.e., temperature increase above the seasonally varying threshold) between summer and winter, the metabolic response of A. triostegus significantly varied between seasons. We found winter MHWs had a stronger effect on thermal sensitivity of standard and maximum metabolic rate with higher Q10 coefficients (i.e., an indicator of thermal stress) during winter MHWs. Hypoxia tolerance did not significantly vary between seasons, but winter MHWs caused a greater reduction in hypoxia tolerance compared to summer, despite the greater absolute temperatures of summer. We discuss the importance of clarifying climate change impacts year-round.

Seasonal variability in metabolic resilience to environmental stress in a Hawaiian reef fish

Cold acclimation induces cardiac remodelling in rainbow trout. This remodeling can include changes in contractile function, cardiac hypertrophy as well as an increase in collagen content. To understand how collagen is regulated in the trout heart we have been studying the function of cultured trout cardiac fibroblasts, the cells responsible for collagen turnover. We have previously found that exposure of these cells to cyclical stretch and transforming growth factor beta 1 (TGF-β1) activate cellular signalling pathways involved in collagen deposition and increase collagen deposition. In the current study, we have examined the influence of different levels of cyclical stretch, testosterone, and angiotensin II (ANG II), on the cell signalling pathways that regulate collagen deposition. We also examined how low temperature and TGF-β1 affected these responses. We found that the effect of cyclical stretch on collagen related signalling pathways is frequency and magnitude dependent. In addition, testosterone treatment led to changes in gene expression that would support an increase in collagen deposition regardless of temperature. This includes changes in the expression of the gene transcripts for matrix metalloproteinase-9, collagen type 1 alpha, and tissue inhibitor of metalloproteinases 2. We also found that 1 µM of ANG II had no effect on collagen-associated gene expression. Our results also suggest that the effect of TGF-β1 on collagen deposition is temperature dependent.  The results of this work provide mechanistic insight into the regulation of collagen deposition in the trout heart and how this is affected by temperature change. This research is funded by NSERC. 

The influence of environmental and endocrine factors on collagen regulatory pathways in rainbow trout (Oncorhynchus mykiss) cardiac fibroblasts

Scorpion venoms contain different types of proteins, peptides, and molecules that can be used against predators or to immobilize prey. Toxins of venom are used for pharmaceutical purposes that require maintaining scorpions in captivity as long as possible for venom extraction purposes.
In this survey, four scorpion species from four genera; Androctonus, Buthus, Hottentotta, and Scorpio, were put in environments that vary in three variables: Diet, Temperature, Humidity. And it Was conducted to discover the influence of the captivity conditions on the venom quantity. During this research, we aim to explore these interactions, to optimize captivity conditions for more venom secretion efficiency. 
In the Light of this study, the results are very promising. This proves the huge impact of the environment on the scorpions. It could be the main key to studying other species or other venomous animals.











Performance of scorpion venom secretion in response to different captive conditions: diet, temperature and humidity on different genera of scorpions

Early-life conditions are important in shaping variation in individual quality and rates of ageing. Our understanding of this relationship between early-life conditions and late-life outcomes is particularly lacking in the context of age-related functional declines, which are often overlooked in favour of age-specific mortality and reproduction. Flight is a metabolically costly trait in insects and is closely associated with fitness in wild burying beetle populations, including Nicrophorus vespilloides. Therefore, flight represents an interesting avenue along which to examine ageing in an expensive functional trait that is closely related to fitness. We manipulated early-life environments through adjusting food availability to explore the role early-life-environments play in shaping lifespan and ageing in flight. Preliminary results find that individuals from higher quality early-life environments (abundance of food) exhibited superior peak flight-speed that was maintained across all assayed ages (10-99 days old). Peak flight speed was seen to decline only in the oldest-aged beetles (90+ days old), an age-range which exceeds that of most studies of ageing performed on this species . However, poorer-quality early-life environments (dearth of food) was associated with increased survival in later life. Beetles displayed a decreased propensity to fly at increasing ages, but no accompanying decrease in time spent in flight was detected . We show that high-quality early-life environments can contribute to improved measures of peak flight performance but have a less pronounced role in shaping patterns of age-related declines in flight. Furthermore, these early-life benefits may also be associated with reduced adult lifespan.

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Brain size, gut size and cognitive abilities: the energy trade-offs tested in artificial selection experiment

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