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| A pair of black-browed albatrosses. The study examines how morphological, behavioral, and phenological traits affecting different stages of the life cycle may evolve under a changing climate. Photo Credit: Samantha Patrick |
Scientific Frontline: Extended "At a Glance" Summary: Ocean Temperature Variability and the Black-Browed Albatross
Key Distinction/Mechanism: While analyzing mean temperature trends "smooths out" data, studying temperature variability reveals that extreme shifts (both hotter and colder) have a threefold greater effect on the growth rate of albatross populations; however, an increasing mean temperature can sometimes buffer these extremes if a species currently lives in an environment cooler than its biological optimum.
Major Frameworks/Components:
- Climate Safety Margin: The concept that species existing below their optimal temperature range may temporarily benefit from an increasing mean temperature, which buffers the negative impacts of extreme warming events.
- Demographic Modeling: Researchers utilized computer models to simulate and compare the distinct demographic outcomes resulting from changes in mean temperature versus changes in temperature variability.
- Age-Structured Impact: Both increased mean temperatures and increased temperature variability result in an overall younger population demographic for the species.
Branch of Science: Population Biology, Evolutionary Biology, Ecology, Climatology, Marine Biology, and Oceanography.
Future Application: These demographic modeling frameworks can be applied to predict the population viability of other species under varying climate scenarios, improving the precision of ecological forecasts and conservation planning.
Why It Matters: Understanding these dynamics is critical for conservation efforts, especially since a shift toward a younger albatross population increases the species' vulnerability to bycatch from commercial longline fisheries, exacerbating their current decline.
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Black-browed albatrosses nesting at the Kerguelen Islands. The study uses more than three decades of demographic and phenotypic observations from this population to investigate whether evolutionary adaptation can buffer climate driven population decline.
Photo Credit: Christopher Barbraud
As the climate changes, species face a critical question: Can they evolve quickly enough to keep pace with their changing environment?
A new study published in the Proceedings of the National Academy of Sciences suggests that, for at least one long-lived seabird, the answer is generally no. Although evolutionary adaptation can improve the prospects of black-browed albatross populations, the study finds that evolution alone is unlikely to prevent population declines under projected climate change; however, substantially limiting greenhouse gas emissions improves the species’ chances of survival, reducing projected extinction probability by approximately half.
Titled “Climate Mitigation Contributes More to Population Persistence Than Evolutionary Adaptation in a Long-Lived Seabird,” the study, co-authored by Woods Hole Oceanographic Institution (WHOI) senior scientist Stéphanie Jenouvrier and colleagues, combines more than three decades of demographic and phenotypic data on the black-browed albatross (Thalassarche melanophris), a seabird native to the Southern Ocean and surrounding seas. The species is pelagic, meaning it spends most of its life gliding far out at sea.
Researchers used an eco-evolutionary population model and climate projections to examine not only how climate affects population dynamics but also how natural selection and evolutionary change might alter the population’s response.
“Evolution can help populations cope with environmental change, but our results show that it has limits,” said Jenouvrier. “For this long-lived seabird, limiting the magnitude of climate change has a much greater effect on population persistence than evolutionary adaptation alone.”
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| A black-browed albatross in flight. Wing length is one of the four functional traits examined in the study and is associated with juvenile survival, a key demographic component of population persistence under climate change Photo Credit: Samantha Patrick |
“Evolutionary rescue” occurs when adaptive evolutionary change allows a population to avoid extinction following environmental deterioration. It is often proposed as a potential buffer against biodiversity loss as the climate changes. But whether evolutionary responses can occur quickly enough remains uncertain, particularly for long-lived species. Because these species have relatively long generation times, environmental conditions can deteriorate and populations can decline before evolutionary responses have time to substantially impact population trajectories.
“Some traits, such as wing length, can help young birds survive, but the key question is whether evolutionary changes in those traits can happen fast enough to keep pace with climate change,” said co-author Joanie Van de Walle of the Université du Québec à Rimouski.
Researchers built a computer model that combined information about albatross demography, how traits are passed from parents to offspring, and projections of future climate. The model tracked how differences among individuals in physical traits, behavior, and breeding timing affected survival and reproduction, allowing natural selection and evolutionary change to emerge over time. It also accounted for uncertainty in population changes and natural fluctuations in climate.
Under the relatively stable climate conditions of the past, allowing the albatross population to adapt through evolution led to larger projected populations. However, under future warming scenarios, evolutionary changes were generally not enough to prevent the population from declining. The researchers also found that passing traits from parents to offspring did little to reduce the risk of extinction. This suggests that a species’ ability to adapt to climate change depends on more than its capacity to pass traits to the next generation; it also depends on how strongly natural selection favors those traits, how environmental changes affect survival and reproduction, and how quickly the climate is changing.
The study reinforces that the capacity for adaptation depends strongly on the environmental conditions under which evolution occurs. When climate change is sufficiently limited, evolutionary responses can contribute to persistence. Under stronger warming, those responses are generally not enough.
Co-author Marika Holland, a scientist at the National Center for Atmospheric Research, stated, “The rate and magnitude of future climate warming impact the effectiveness of evolutionary adaptation. Reducing future climate change by decreasing greenhouse gas emissions slows population decline and enables evolutionary adaptation to promote population persistence.”
“Our results show that evolutionary rescue depends not only on how quickly the environment changes but also on where evolution acts across the life cycle,” said Jenouvrier. “Evolution can help when adaptation improves the parts of the life cycle that matter most for population growth, but limiting the rate and magnitude of climate change gives adaptation a much greater chance to contribute to population persistence.”
Published in journal: Proceedings of the National Academy of Sciences
Authors: Stéphanie Jenouvrier, Jimmy Garnier, Marika Holland, Joanie van de Walle, Samantha C. Patrick, Timothée Bonnet, Karine Delord, Francesco Ventura, Christophe Barbraud, and Henri Weimerskirch
Source/Credit: Woods Hole Oceanographic Institution
Edited by: Scientific Frontline
Reference Number: ebio092226_01
