Polarised

Polar bears are the poster child of the Arctic, and under serious threat thanks climate change and the reduction of the polar ice caps. But one person’s loss is another one’s gain, and due to warming temperatures case grizzly bears are able to move further north as the icy conditions (and soft, blubbery seals – the preferred food source for polar bears) recede. This means that grizzlies and polar bears are more likely to come into contact with each other and (interestingly) are able to hybridise and produce a pizzly (or grolar) bear.

Interestingly, and unlike most hybrids, pizzly bears are quite robust (having traits of both parents mean they are likely able to exploit the habitats and food sources of both species) and able to produce viable offspring as shown in a study from 2017 that used genetic analysis to determine ancestry. They found some polar-grizzly hybrids to be 75:25 grizzly:polar bear, which means that one parent (in this case the mother) was a polar-grizzly hybrid to begin with.

As the likelihood of grizzlies and polars coming into contact with each other increases, we expect the number of hybrids in the population to increase as well. This won’t be the first time that these two species interbreed but it does still pose an interesting question of how we view ‘species’, as well as how we would approach hybrids in terms of conservation. Are we okay with polar-grizzly hybrids? Do we see them as a new species or simply an unwanted side effect of species range shifts? Do we view the northward-moving grizzlies as invasive?

Read more: Recent Hybridization between a Polar Bear and Grizzly Bears in the Canadian Arctic


Tanya Strydom is a PhD candidate at the Université de Montréal, mostly focusing on how we can use machine learning and artificial intelligence in ecology. Current research interests include (but are not limited to) predicting ecological networks, the role species traits and scale in ecological networks, general computer (and maths) geekiness, and a (seemingly) ever growing list of side projects. Tweets (sometimes related to actual science) can be found @TanyaS_08.

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