Tag Archives: adaptation

Evolution Earth documentary comments on polar bear survival & adaptation: let’s see how they do

Just a heads-up that this week, PBS in North America will broadcast the “polar” episode of a new documentary called “Evolution Earth.” In my area, it’s scheduled for Wednesday, September 27 at 10:00 PM. It remains to be seen whether this is really about evolution or (given those involved in its production) simply more climate change propaganda similar to that promoted by Attenborough, but I intend to watch and report back.

About the Show: “Evolution Earth embarks on a global expedition to reveal the animals keeping pace with a planet changing at superspeed. Heading out across the globe to distant wilds and modern urban environments, five episodes track how animals are moving, using ingenuity to adapt their behavior, and even evolving in unexpected ways.

We follow heart-warming tales of resilience that redefine our understanding of evolution, and hint at how nature can show us a path towards a sustainable future for Planet Earth. The series is narrated by Dr. Shane Campbell-Staton, who guides us through each episode in an intimate narrative style, drawing on his background as an evolutionary biologist.”

Episode 4 | IceAt the planet’s frozen extremes, shifts in animal movement and behavior reveal vital information about our future world. Examine polar bears in the Arctic, penguins in Antarctica and other animals surviving in icy worlds.

Find tips for watching outside the US here.

UPDATE 27 September 2023: Well, as I expected, this show was full of Attenborough-style nonsense about starving polar bears waiting for sea ice to form along Western Hudson Bay, the bears presented as “canaries in a coal mine” indicators of climate change, with an activist scientist saying she’s “pissed” about climate change. They used charts of the very distinctive pattern of sea ice formation that took place in November 2020 to illustrate how freeze-up was “later and later each year” even though 2020 was one of the earliest freeze-ups on record (bears were successfully hunting from shorefast ice as early as 30 October). A waste of 15 minutes: I couldn’t bear to watch what they did with the penguins.

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Birthing season for harp seals in Labrador Sea just in time to feed hungry polar bears

The main birthing period for NW Atlantic harp seals has arrived. Local populations of ringed and bearded seal pups will soon follow but in the Gulf of St. Lawrence in eastern Canada, the pupping season for harp seals that is usually in progress by this time has likely been redirected north due to lack of suitable ice conditions. Sea ice off Labrador and Newfoundland is in good condition and this is where the vast majority of the global population go to give birth (ca. 7.6 million vs. 1.5 million in the White Sea and 434,000 in east Greenland).

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Critical spring feeding for polar bears is over – sea ice levels are now irrelevant

Polar bears in virtually all regions will now have finished their intensive spring feeding, which means sea ice levels are no longer an issue. A few additional seals won’t make much difference to a bear’s condition at this point.

Relative importance of seasons polar bear graphic_PolarBearScience_June2016

The only seals available on the ice for polar bears to hunt in early July are predator-savvy adults and subadults but since the condition of the sea ice makes escape so much easier for the seals, most bears that continue to hunt are unsuccessful – and that’s been true since the 1970s. So much for the public hand-wringing over the loss of summer sea ice on behalf of polar bear survival! Continue reading

Terrestrial food fight amongst polar bear researchers reflects political differences

With a few big guns on one side and some fringe folk on the other, a dichotomy of opinion has developed amongst polar bear researchers regarding whether or not consumption of land-based foods is making a difference to polar bear survival (or is likely to in the future).

Polar bears eating terrest foods WHB_Rockwell press release

It’s been going on for a while now. Last year, two US Geological Survey members of the IUCN Polar Bear Specialist Group (PBSG) apparently got fed up with the scatter-shot of papers promoting terrestrial foods as a possible salvation for polar bears (e.g. Iles et al. 2013;  Iverson et al. 2014; Rockwell and Gormezano 2013a, 2013b). In April, they published a canon volley of a paper meant to blow all that ‘polar-bears-might-survive’ talk out of the water once and for all (Rode et al. 2015).

Note that although the PBSG didn’t bother to update their website with the IUCN Red List assessment when it came out last November, they had a link up to the USGS terrestrial feeding paper within 16 days (with an editorial summary in the “NEWS” section as well as a listing of the paper in the “RECOMMENDED READING” section). As I suggest below, this difference in treatment may not be a coincidence.

However, another group of non-PBSG researchers  haven’t given up just yet, as shown by the title chosen for the most recent news report (Alaska Dispatch News, 16 June 2016) on the just-finished International Bear Conference:

Want to know how a changing climate is affecting polar bears? Look at what they’re eating.

Apparently, Jeff Welker, a University of Alaska Anchorage researcher who is co-author on two recent papers on the subject of polar bear consumption of terrestrial foods (Tartu et al. 2016 and Rogers et al. 2015), gave a presentation at the conference that raised this topic yet again. His talk came on the heels of an earlier presentation by Todd Atwood, who suggested Southern Beaufort polar bears might benefit from staying onshore to eat left-over whale scraps instead of staying on the sea ice during the summer (even though he had no data to support that opinion – as I discussed in this post).

Here’s the question: is this dispute really about what polar bears eat or don’t eat when they’re on land – or is it symptomatic of the underlying politics of polar bears? [CBC documentary video by that name here]
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Paleoclimate + genetic study confirms: Arctic species adapted to sea ice changes

A new paper that combines paleoclimatology data for the last 56 million years with molecular genetic evidence concludes there were no biological extinctions [of Arctic marine animals] over the last 1.5M years despite profound Arctic sea ice changes that included ice-free summers: polar bears, seals, walrus and other species successfully adapted to habitat changes that exceeded those predicted by USGS and US Fish and Wildlife polar bear biologists over the next 100 years.

Healy Aug  24 2015 Polar-Bear V Tim Kenna

Cronin, T. M. and Cronin, M.A. 2015. Biological response to climate change in the Arctic Ocean: the view from the past. Arktos 1:1-18 [Open access] http://link.springer.com/article/10.1007/s41063-015-0019-3

Thomas Cronin is a USGS paleoclimatologist at the Eastern Geology and Paleoclimate Science Center, and Matthew Cronin is a molecular geneticist at the University of Alaska Fairbanks (see previous posts here and here about Matt’s work on the genetics of polar bear evolution).

From the Abstract:

Arctic climatic extremes include 25°C hyperthermal periods during the Paleocene-Eocene (56–46 million years ago, Ma), Quaternary glacial periods when thick ice shelves and sea ice cover rendered the Arctic Ocean nearly uninhabitable, seasonally sea-ice-free interglacials and abrupt climate reversals.

The final discussion and two summary graphics from this paper (copied below) are especially useful:

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Natural selection helps polar bears adapt to sea ice variability – which means some bears die

Evolution is not just for the long-term – natural selection also goes on over short time periods. In the case of polar bears, this adaptation is almost certainly critical for its long-term survival.

Hudson Bay female with cub_Wapusk_Thorsten Milse_Gov CA

Hudson Bay female with cub Wapusk National Park, Thorsten Milse, Government of Canada

Not all polar bears are identical — that is the reality that allows natural selection to operate.

I will argue that early breakup years in Western Hudson Bay weed out individual polar bears that do not have the physiological or behavioral characteristics necessary to be useful members of the population – and that this is a good thing for the entire population.

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Evolution by geneticists again: yet another date for when polar bears arose

The latest addition to the never-ending story of when-and-why polar bear evolution took place according to geneticists (Liu et al. 2014 — the 8th such paper in less than 4 years, if you can believe it) is getting way, way more media attention than it deserves.

Lui et al. 2014 figure provided in the abstract.

Liu et al. 2014 figure provided in the abstract.

This multi-member research team used a new data set (mostly Scandinavian brown bears and Greenland polar bears, for a change) to add not much of anything new on the evolutionary insight front except yet another estimate of when polar bears came to be.1

However, the real focus of the paper is the description of their finding of a few genetic differences between brown bears and polar bears that they identified. They found a few genes in polar bears were different than brown bears and made a boat load of assumptions about what these might mean.

Their discovery was not accompanied by any attempt to demonstrate that the changes in gene architecture they found also involved a change in the function of the genes or were associated with different effects on bear physiology. If a changed gene cannot be shown to act differently or to have a demonstrated new physiological effect on the animal in question, the changes themselves mean next to nothing – especially for evolution!

That’s my take – see what you think. It looks long but a lot of it is quotes.
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Polar bears move around as sea ice habitat changes – this is what resilience looks like

Oddly, it seems some people expect polar bears to sit around and suffer (or die) when local conditions deteriorate, rather than move elsewhere.

PolarBear_2008_USGS

While there are perhaps a few places where moving is not really an option over the short term, over the long term (more than one season) polar bears are free to shift to another locale if ice conditions change (either too much ice or too little).

An announcement by the WWF last week (10 April) caught my eye, as it talked about bears moving from one area to another because of changing ice conditions — as if this was surprising, extraordinary and newsworthy. That said, at least they weren’t suggesting the bears are all going to die because of declining ice, which is a huge improvement.

See what you think of this part of the press release (below), in the context of what we know about the movement of bears between regions:

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