In the largest study of its kind, this approach was used to look more closely at the diets of killer whale from the eastern and northern coasts of Canada all the way to northern Norway. It provides the most detailed overview of North Atlantic killer whales diets to date. As climate change leads to a northward redistribution of killer whales, the results have implications not only for the health and survival of these killer whales, but also in terms of potential impacts on sensitive species within Arctic ecosystems.

A new tool to keep track of shifting diets

“In a context of climate change, it becomes increasingly urgent to understand and be able to quantify killer whale diets and how they are changing so that we can foresee the potential impacts on local food webs,” says Anaïs Remili, a PhD candidate in the Department of Natural Resource Sciences at McGill University and the first author on a paper published in Journal of Animal Ecology. “By measuring the composition of the fatty acids of approximately 200 killer whales and of 900 of their prey of different species, we were able estimate the specific proportions of each prey species in the whales’ diets. This means that scientists can potentially keep track of any shifts in these diets in the future.”

Orca food habits vary — by region and individual

The team found that killer whales have very different diets throughout the North Atlantic. In some areas, killer whales prefer to consume other whales: belugas and narwhals in the Eastern Canadian Arctic and baleen whales and porpoises in Eastern Canada.

Killer whales feed predominantly on fish, especially herring in the Eastern North Atlantic (Norway, Faroe Islands, Iceland), and in the Central North Atlantic (Greenland) they primarily eat seals.

Interestingly, however, the McGill researchers also found that not all the whales in any given location feed on the same prey. For example, in the Eastern Canadian Arctic, half of the whales eat mainly belugas and narwhals, while the other half consume mainly ringed seals. In Greenland, killer whales consumed a mixture of all available prey. Lastly, in Iceland, the Faroe Islands, and Norway, most whales are herring eaters, but a small number of whales in Norway and Iceland also consume a substantial proportion of marine mammals such as porpoises and seals. It is the first time that researchers have been able to detect individual diet preferences with this level of detail.

“Quantifying the diets of killer whales and other top predators is crucial in a context of changing environments, because it can provide insights into how these animals adapt to shifts in their prey populations and habitat conditions,” adds Melissa McKinney, the senior author on the paper, an Assistant Professor in the Department of Natural Resource Sciences at McGill and the Canada Research Chair in Ecological Change and Environmental Stressors. “Our results also point to the need for further research on the ecology of the individuals since we found such large differences among individuals of the same populations.”

“The study is really understanding the genetics of skeleton,” says senior author Nora Renthal of Boston Children’s Hospital and Harvard University. As a pediatric endocrinologist who cares for children with skeletal diseases, she is interested in understanding how bones grow. “Height is a good starting point to understand the relationship between genes, growth plates, and skeletal growth because we can measure the height of every human being.”

To pinpoint height-associated genes, the team screened 600 million mouse cartilage cells to identify genes that, when deleted, can alter cell growth and maturation. These types of cellular changes in the growth plate are known to lead to variations in human height. The search turned up 145 genes mostly linked to skeletal disorders and are crucial for growth plate maturation and bone formation.

The team then compared the discovered genes with data from genome-wide association studies (GWAS) of human height. GWAS allows researchers to survey the entire human genome to identify hotspots where “height genes” are located in our DNA. But these regions can contain multiple genes, making it hard for researchers to track down and study an individual target.

“That’s kind of like looking for your friend’s house, but you only know the zip code,” says Renthal. “It’s difficult.”

The comparison revealed that genes affecting cartilage cells overlap with hotspots from human height GWAS, precisely locating genes in our DNA that likely play a role in determining our stature. Renthal and her team also discovered that many of the GWAS suggested height genes led to early maturation in cartilage cells. These findings suggest that genetic changes affecting cartilage cell maturation may influence height more.

Renthal notes that studies in mouse cells may not fully translate to humans, and GWAS are observational studies that cannot fully illustrate the cause and effects of height. But her study provides a novel method to bridge the two methods and provide new insights into human genetics.

Next, the team plans to use the method to understand hormones’ effect on cartilage cells. They will also look into some of the 145 genes that have no known connection to skeletal growth. The investigation may reveal new genes and pathways that play a role in the bones.

“I see patients with skeletal dysplasia, where there isn’t any treatment because genetics made their bones grow this way,” says Renthal. “It’s my hope that the more we can understand about the biology of the growth plate, the more we would be able to intervene at earlier times in growing skeletons and the life of a kid.”

To discover exoplanets, planets which orbit stars other than the Sun, by imaging astronomers have up until now used “blind surveys”: stars are selected for imaging consider factors such as age and distance but are otherwise unbiased. However, blind surveys find planets very infrequently. Knowing where to look would help increase detection rates.

An international research team led by Subaru Telescope, the University of Tokyo, the University of Texas-San Antonio, and the Astrobiology Center of Japan, searched for hints of unknown planets in the data from the European Space Agency’s Gaia mission and its predecessor, Hipparcos. The team identified a star, HIP 99770 located 133 light-years away in the constellation Cygnus, whose motion suggests that an unseen planet is gravitationally pulling on it. Direct imaging observations with the Subaru Telescope detected the planet, HIP 99770 b.

The newly discovered planet is 14-16 times more massive than Jupiter. Its orbit is just over 3 times further from its star than Jupiter is from the Sun. The planet is 10 times hotter than Jupiter, with signs of water and carbon monoxide in its atmosphere.

A decade from now, astronomers hope to image a potentially-habitable planet with a size and temperature like the Earth using observatories like the Thirty Meter Telescope (TMT). Compared with HIP 99770 b, this Earth twin will be smaller and closer to its star, traits that will make it harder to detect. But with precise motion measurements, researchers will know where to look in this game of planetary hide and seek.