Media – Centre for Geometric Biology: Recent Episodes
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This article is republished from The Conversation under a Creative Commons license. Read the original article.
All animals need energy to live. They use it to breathe, circulate blood, digest food and move. Young animals use energy to grow, and later in life, to reproduce.
Increased body temperature increases the rate at which an animal uses energy. Because cold-blooded animals rely on the thermal conditions of their environment to regulate their body temperature, they’re expected to need more energy as the planet warms.
However, our new research, published today in Nature Climate Change, suggests temperature is not the only environmental factor affecting the future energy needs of cold-blooded animals. How they interact with other species will also play a role.
Our findings suggest cold-blooded animals will need even more energy in a warmer world than previously thought. This may increase their extinction risk.
Young animals use energy to grow, and later in life, to reproduce.What we already knowThe amount of energy animals use in a given amount of time is called their metabolic rate.
Metabolic rate is influenced by a variety of factors, including body size and activity levels. Larger animals have higher metabolic rates than smaller animals, and active animals have higher metabolic rates than inactive animals.
Metabolic rate also depends on body temperature. This is because temperature affects the rate at which the biochemical reactions involved in energy metabolism proceed. Generally, if an animal’s body temperature increases, its metabolic rate will accelerate exponentially.
Most animals alive today are cold-blooded, or “ectotherms”. Insects, worms, fish, crustaceans, amphibians and reptiles – basically all creatures except mammals and birds – are ectotherms.
As human-induced climate change raises global temperatures, the body temperatures of cold-blooded animals are also expected to rise.
Researchers say the metabolic rate of some land-based ectotherms may have already increased by between 3.5% and 12% due to climate warming that’s already occurred. But this prediction doesn’t account for the animals’ capacity to physiologically “acclimate” to warmer temperatures.
Acclimation refers to an animal’s ability to remodel its physiology to cope with a change in its environment.
But rarely can acclimation fully negate the effect of temperature on metabolic processes. For this reason, by the end of the century land-based ectotherms are still predicted to have metabolic rates about 20% to 30% higher than they are now.
Having a higher metabolic rate means that animals will need more food. This means they might starve if more food is not available, and leaves them less energy to find a mate and reproduce.
As climate change raises global temperatures, the body temperatures of cold-blooded animals are also expected to rise.Our researchPrevious research attempts to understand the energetic costs of climate warming for ectotherms were limited in one important respect. They predominantly used animals studied in relatively simple laboratory environments where the only challenge they faced was a change in temperature.
However, animals face many other challenges in nature. This includes interacting with other species, such as competing for food and predator-prey relationships.
Even though species interact all the time in nature, we rarely study how this affects metabolic rates.
We wanted to examine how species interactions might alter predictions about the energetic costs of climate warming for cold-blooded animals. To do this, we turned to the fruit fly (from the genus Drosophila).
Fruit fly species lay their eggs in rotting plant material. The larvae that hatch from these eggs interact and compete for food.
Our study involved rearing fruit fly species alone or together at different temperatures. We found when two species of fruit fly larvae compete for food at warmer temperatures, they were more active as adults than adults that didn’t compete with other species as larvae. This means they also used more energy.
From this, we used modelling to deduce that species interactions at warmer global temperatures increase the future energy needs of fruit flies by between 3% and 16%.
These findings suggest previous studies have underestimated the energetic cost of climate warming for ectotherms. That means purely physiological approaches to understanding the consequences of climate change for cold-blooded animals are likely to be insufficient.
Previous studies have underestimated the energetic cost of climate warming for ectotherms.Let’s get realUnderstanding the energy needs of animals is important for understanding how they’ll survive, reproduce and evolve in challenging environments.
In a warmer world, hotter ectotherms will need more energy to survive and reproduce. If there is not enough food to meet their bodies’ energy demands, their extinction risk may increase.
Clearly, we must more accurately predict how climate warming will threaten biodiversity. This means studying the responses of animals to temperature change under more realistic conditions.
By Craig White and Dustin Marshall This article is republished from The Conversation under a Creative Commons licence. If you think about “unravelling the mysteries of the universe”, you probably think of physics: astronomers peering through telescopes at distant galaxies, or experimenters smashing particles to smithereens at the Large Hadron Collider. When biologists try to … Continue reading The Conversation: Why are bigger animals more energy-efficient? A new answer to a centuries-old biological puzzle
By Dustin Marshall This article is republished from The Conversation under a Creative Commons licence. Apart from mammals and birds, most animals develop as eggs exposed to the vagaries of the outside world. This development is energetically “costly”. Going from a tiny egg to a fully functioning organism can deplete up to 60% of the … Continue reading The Conversation: From crocodiles to krill, a warming world raises the ‘costs’ paid by developing embryos
By Martino Malerba, Craig White, Dustin Marshall, and Liz Morris, Monash University. This article is republished from The Conversation under a Creative Commons licence. About half of the coastline of Europe, the United States and Australasia is modified by artificial structures. In newly published research, we identified a new effect of marine urbanisation that has … Continue reading The Conversation: Daylight robbery: how human-built structures leave coastal ecosystems in the shadows
By Dustin Marshall and Liz Morris, Monash University This article is republished from The Conversation under a Creative Commons licence. One hectare of ocean in which fishing is not allowed (a marine protected area) produces at least five times the amount of fish as an equivalent unprotected hectare, according to new research published today. This … Continue reading The Conversation: No-take marine areas help fishers (and fish) far more than we thought
Offspring size affects all aspects of an organism’s life, from birth through to reproduction, and studies show that larger offspring do better overall. Despite the long standing interest in the drivers of differences in offspring size, most studies focus only on one particular taxon or system. Dustin Marshall, Amanda Pettersen and Hayley Cameron were interested … Continue reading Causes and consequences of variation in offspring size
Humans are continually modifying the marine environment either directly, with activities such as fishing, or indirectly as with climate change or the introduction of invasive species. A common consequence of these activities is a change in the body size of individuals that make up an ecological community. Understanding the impacts of such changes on the way … Continue reading Time to go back to school? Geometry helps predict change in ecosystem function
Authors: Diego R Barneche, D Ross Robertson, Craig R White, and Dustin J Marshall Published in: Science, volume 360, issue 6389 (11 May 2018) Abstract Body size determines total reproductive-energy output. Most theories assume reproductive output is a fixed proportion of size, with respect to mass, but formal macroecological tests are lacking. Management based on that … Continue reading Fish reproductive-energy output increases disproportionately with body size
An international study led by the Centre for Geometric Biology has found that larger fish are much more important to feeding the planet than previously thought. The research confirmed what field biologists have long suggested: that larger mothers reproduced disproportionately much more than smaller ones. Furthermore, larger mothers may produce offspring that perform better and … Continue reading Bigger is better when it comes to female fish and feeding the planet
Pathogens, or disease producing organisms, will inevitably encounter hosts that differ in their resistance to infection and theory suggests that this will affect pathogen evolution. If a pathogen routinely only encounters one type of host resistance, it will develop a specialist strategy that dictates the severity of infection. It is likely that the age and … Continue reading Understanding how age and sex can influence host-pathogen interactions
The Centre’s Dr Martino Malerba spoke to Corey Green on community radio 3CR about his research into phytoplankton. Phytoplankton create about 50-85% of the world’s oxygen, and they are the basis of aquatic food chains. Phytoplankton numbers are affected by pollution and climate change.