The climatic conditions are changing at an unprecedented pace and affect mainly fish, amphibians and reptiles, ectothermic animals that are unable to generate their own internal heat. With heat waves and rising temperatures, these organisms experience not only increased growth rates and heat stress, but also further aging.
Fish, amphibians, and reptiles are animals known as ectotherms. This means that they cannot actively control their internal temperature and are regulated by that of the environment. In the face of a rise in temperature caused by climate change, these organisms will experience an increase in their body temperature, which will have serious consequences for them.
In fact, environmental changes are already changing them, as several studies in recent years have shown. Their growth rates are already faster when temperatures are higher and they are exposed to heat stress from extreme events such as heat waves.
“Heat waves take animals out of their thermal preferences and even reach their temperature tolerance limits. The longer and more frequent the heat waves, the more they affect the physiology of the ectotherms, ”explains Germán Orizaola, researcher at the Joint Institute for Biodiversity Research at the University of Oviedo, to SINC.
Now this expert, together with an international team of scientists, has investigated other effects of temperature rise on fish, amphibians and reptiles in the scientific literature. The results of this opinion article published in the magazine Global Change Biologysuggest that climate change will affect their aging rates.
“Higher growth rates lead to physiological imbalances in ectotherms and increase, for example, the oxidative damage to proteins and DNAThis can also affect the telomeres, the repeated stretches of non-coding DNA at the ends of the chromosomes, ”Orizaola says.
Telomeres, which provide stability and protect coding sequences from loss at the end of the chromosome, can be shortened or lost with each cell division. The faster a cell divides and the higher the oxidative stress, the faster the telomere erodes.
“Since telomeres protect the DNA, the faster the telomeres are lost, the faster the cells break down and the body ages. This clear connection between climate change and aging is described for the first time in our article, ”explains the researcher.
Shorter life expectancy in the population
This rapid aging caused by climate change can have serious consequences for the natural population. “A fairly clear consequence is that if the life expectancy of individuals in a population is reduced, their ability to produce offspring can be compromised,” Orizaola warns.
With a shortened lifespan, any external phenomenon such as severe drought, flood, disease, or heat wave reduces the recovery capacity of the populations and the time to produce enough offspring decreases. As scientists point out, the effects on the aging of one species can also affect other species that are part of its ecological network, for example if they affect the number of prey, competitors, parasites, etc.
“This is an area that has barely been explored, but all indications are that it could be another potential problem for wildlife exposed to climate change,” says the University of Oviedo co-author. In his opinion, knowing the effects of the climate crisis on the aging of the ectotherm would help develop better protection and management programs.
“For example, if a species (such as a fish) is caught for commercial reasons, it is important to know that climate change can shorten its lifespan if catch rates are defined and population demographics are assessed,” he says.
On the other hand, species that are already endangered and have a small population size can be even more threatened if life expectancy is to be reduced. Therefore, protective measures should be implemented. For other species, whose habitat can be affected by rising temperatures, “it may be necessary to move these individuals to a more suitable habitat,” concludes the scientist.
Reference: “Climate change and aging in ectotherms” by Pablo Burraco, Germán Orizaola, Pat Monaghan and Neil B. Metcalfe, August 24, 2020, Global Change Biology.
DOI: 10.1111 / gcb.15305