{"id":16915,"date":"2011-02-24T00:22:39","date_gmt":"2011-02-24T08:22:39","guid":{"rendered":"http:\/\/planetsave.com\/?p=16915"},"modified":"2011-02-24T00:22:39","modified_gmt":"2011-02-24T08:22:39","slug":"grolar-bears-amp-narluga-whales-arctic-warming-may-promote-hybrid-animals-video","status":"publish","type":"post","link":"https:\/\/planetsave.com\/articles\/grolar-bears-amp-narluga-whales-arctic-warming-may-promote-hybrid-animals-video\/","title":{"rendered":"'Grolar' Bears & 'Narluga' Whales? – Arctic Warming May Promote Hybrid Animals [VIDEO]"},"content":{"rendered":"

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In 2006, Arctic hunters shot and killed a strange-looking, white bear. It was strange because the bear had large patches of brown fur in its coat. Subsequent genetic analysis showed that it was in fact a cross between a polar bear and a grizzly bear (making it a “grolar” or “pizzly” bear).<\/p>\n

Apparently, more grizzlies\u00a0 are now moving further north into territory that was once an effective barrier to them due to the cold.<\/p>\n

Normally thought of as just “flukes” of Nature or the manipulated outcomes of\u00a0 zoo breeding experiments (see: ‘Liger’),\u00a0 examples of such out-breeding in the wild are not very common, but can result from dramatic changes in habitat. But it appears as though inter-breeding is becoming more common; in 2009, a bowhead (Balaena mysticetus<\/em>) and right whale (Eubalaena<\/em> spp.) hybrid was spotted, and, more recently, sightings of\u00a0 spotted seal (Phoca largha<\/em>) and ribbon seal (Histriophoca fasciata<\/em>) crosses have been made.<\/p>\n

These two examples are biologically noteworthy in another regard: they represent cross-breeding between two different Genera<\/em>, which is a wider taxonomic grouping than specie<\/em> (note: the polar and grizzly bears share the same Genus<\/em>, but are different species).<\/p>\n

Off-spring of these couplings are generally fertile and healthy. This is because, in each case, the cross-breeding creatures possess the same number of chromosomes (incompatible chromosome number results in mal-developed gametes), but differ in the types of alleles, or gene variants (making the pairing up of recessive<\/em> alleles, and thus the emergence of deleterious traits, less likely).<\/p>\n

Getting back to the seeming rise in hybrid occurrences…<\/p>\n

It is theorized that the breaking up and melting of Arctic sea ice due to warming is the basic driver of this emerging, inter-breeding trend.<\/p>\n

As land and water warm they become more habitable for creatures adapted to warmer conditions.\u00a0 Also: this ‘El Norte’ migration of\u00a0 land animal species may be buttressed by pressure from shrinking habitat in more southerly climes (e.g., grizzly habitat is diminishing due to several factors, including huge loss of montane pine forest habitat due to decimation from pine beetles, also partly blamed on warming impacts).<\/p>\n

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A beluga whale<\/figcaption><\/figure>\n

A team of ecologists lead by Brendan Kelly of the National Marine Mammal Laboratory<\/a>, in Juneau Alaska, has been documenting cases of cross-breeding and out-breeding and they have identified 34\u00a0 potentially cross-breeding animal pairs — including two distinct (Genera) pairs of porpoises, seals and whales. One of these latter pairings is that between the narwhal (Monodon monoceros<\/em>) and the beluga whale (Delphinapterus leucas<\/em>) — yielding the “narluga” whale of this post’s title. Recently, sightings of narlugas have been made in the Bering Sea.<\/p>\n

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Narwhals "tusking"<\/figcaption><\/figure>\n

The team’s findings and theories were published in the journal Nature<\/em>, under the title: ‘The Arctic melting pot’<\/a>, in late 2010.<\/p>\n

As climate change and Arctic warming continue, these hybrid animals will likely increase in number.<\/p>\n

According to Kelly, the biggest threat in the near term is to already endangered, native species, like the polar bear. Already shrinking in numbers as their habitat shrinks, polar bears will come under increasing pressures from the influx of a competing species*, as well as from the new cross-breeds. Kelly and his team are concerned that, if this hybridization trend continues, the polar bear and other imperiled animals native to the Arctic will soon disappear in the wild.<\/p>\n

The inter-breeding trend, if it is indeed a trend, may be an even worse threat to the right whale, whose numbers hover around 200.<\/p>\n

But not all scientists in the field agree here. Many ecologists think that hybrids are less fit<\/em> genetically and others point out the lack of solid evidence that hybridization in the Arctic is<\/em> in fact increasing. Further, the very idea of a hybrid being somehow a “corruption” of the “pure” species has garnered its share of criticism from fellow scientists.<\/p>\n

\"\"<\/a>But perhaps, the concern here is for preservation of the original<\/em>, or the most long-standing, of creatures…At least until human-induced warming came along. Does\u00a0 the polar bear deserve some credit or special status here — enough to help protect its existence?<\/p>\n

Is preserving the “bloodline” acceptable when it comes to such amazing examples of animal life? Do the same rules of “survival of the fittest” apply when it is willful human industrial activity that is partly to blame?<\/p>\n

\"\"<\/a>And it’s not all good news for the hybrids. According to theory, although the initial off-spring of cross-breeds are generally fertile, over time and continuous mating, recessive alleles (present in every genome) will build up in a population, increasing the likelihood of recessive pairing (what is needed for a recessive, non-dominant, trait to appear), resulting in less genetic fitness and decreased chances of long-term survival.<\/p>\n

Developing effective survival traits takes time (and perhaps also a stable environment). An accelerating rate of evolutionary pressure\/change may simply be too much for some species. Competition from heartier hybrids may likely shrink native populations, forcing more in-breeding, weakening genetic fitness.<\/p>\n

And there are emerging signs of maladaptation<\/em> amongst some cross-breeds: a male narluga was recently spotted off Greenland lacking its spiral tusk (which is important for sexual selection<\/em>), and, in a German zoo, grizzly-polar hybrids exhibit seal-hunting behavior, but lack the polar bear\u2019s\u00a0 swimming capability.<\/p>\n

Alternatively, these occurrences could be the result of male fighting (over mates), in the case of narlugas, and environmental factors<\/em> (captive\/fed animals), in the case of the grolars.<\/p>\n

These could be exceptions, of course. Much more data is needed to validate these theories. But, if increasing numbers of these hybrids are<\/em> being driven by accelerated Climate Change\/Arctic Warming, then we have a cautionary lesson: that the speeding up evolutionary pressures, the forcing of animals into rapid adaptive modes, may not produce biologically favorable outcomes.<\/p>\n

Quoting Kelly from an interview with Live Science<\/em>: “”This change is happening so rapidly that it doesn’t bode well for adaptive responses.”<\/p>\n

Watch a collaged video about the grizzly-polar hybrid (warning: graphics are in Japanese and some footage may be upsetting to some viewers; article continues below):<\/strong><\/p>\n