Why Hybrid Animals May Take Over the North

foreigner a trophy The hunter shot what he thought was a polar bear in the Northwest Territories of the Canadian Arctic, but what he killed instead was something never before documented in the wild a bear with the white fur of a polar bear but With long claws, a shallow humped face and brown patches of fur like a Grizzly, this was definitely not a typical bear. Officials confiscated the creature, of its unknown species, and, under interrogation, a DNA test was performed which led them to discover that it was neither a Grizzly nor a polar bear, but rather a

hybrid

with a polar bear mother and a grizzly bear father. , the first discovered in the wild and while this

hybrid

, now called pisley or growler, was a rare discovery, it may be just the beginning of an era of these hybrid bears.

Since then, sightings of the hybrids have increased with A 2017 study shows eight hybrids arising from a single female polar bear that mated with two brown bears, but it's not just the bears. In 1990, a scientist noticed a very strange skull hanging on the wall of an Inuit hunter. neither a beluga whale skull nor a narwhal skull, but something in between. Later genetic analysis would show that the skull belonged to a Beluga hybrid narwhal. The first confirmed case. Hybrids are commonly considered an interesting anomaly, but other than that evolutionarily useless, the thinking has always been uniform. If a hybrid can exist, that is the end of the line, as hybrids themselves are believed to be incapable of producing offspring, but now scientists are understanding that there is more to the story and the current state of the world.

Experts believe we could be entering a new era. of hybrid

animals

, but what benefit can mating between lines of species give? What is pushing

animals

to hybridize and how is it possible for animals of different species to mate? The hybrid mix of a tiger and a lion is created when two different species interbreed and produce invertebrate offspring. It has always been thought to be something strange, logically it seems that different species should not be able to mate due to the very definition of the word species. A widely accepted concept in biology is called the biological species concept and it says that organisms belong to the same species if they can interbreed and produce viable, fertile offspring.

Speciation is a gradual process that relies on random mutations to introduce new traits that create a subpopulation. more suited to an environment or finding a mate, they eventually become isolated both physically and genetically due to a divergent genome resulting in new species that cannot mate with their ancestors or each other due to a series of barriers called reproductive isolation mechanisms. in two ways, the first is by making it impossible for two different species to physically mate. These are pre-zygotic barriers, meaning they

take

place before the formation of a zygote, which is the result of the fusion of a sperm and an egg.

These include mechanisms such as living in different habitats or having different courtship behaviors or not having reproductive organs that fit together, the other way reproductive isolation works is by making it impossible for embryos to develop into healthy fertile adults. These are called postzygotic barriers and are usually the result of a chromosome mismatch. When two animals mate, each one contributes the same number of chromosomes to their offspring. Human cells contain 46 chromosomes, for example, 23 come from our mothers and 23 from our fathers, but now let's look at the horses and donkeys that diverged from their common ancestor around 4 million.

Years ago, donkeys and horses had a big problem if they wanted to mate. Horses have 64 chromosomes, while donkeys only have 62. When they mate, the mule. The offspring get 32 ​​chromosomes from their horse mother and 31 chromosomes from their donkey father, this is close enough to create. an animal alive but not close enough to have its own offspring in order for a male mule and a female mule to produce their own offspring would have to produce gametes to form gametes the chromosomes need to pair, which requires genetic similarity between the chromosomes and the same Donkey and horse DNA numbers are similar enough for some pairs of chromosomes, such as pairs 1 to 13 and horse chromosomes 14 to 19 and donkey chromosomes 25 to 30, but the rest have no direct homologues in the other species.

Cell division that creates haploid gametes is impossible due to reasons like this. Researchers have long considered animal hybridization in the wild to be of little importance in the big picture of evolution, but it turns out that as environments change the barriers that separate species from one another change. another may become less rigid or disappear entirely, opening the door for animals to mate across species lines. Genetically post-zygotic barriers can be broken if two species diverged sufficiently recently on the tree of life. Horses and donkeys diverged around 4 million years ago and at that time. their genetics drifted to a point where they could mate, but their chromosomes were no longer aligned for most animal combinations, even getting that far is impossible, but grizzly bears and polar bears only diverged about 150,000 ago years, which means their genetics haven't had a chance to deviate.

To the extent that each still has 74 chromosomes and enough genetic similarity for the two species to mate and produce viable fertile offspring, as for the narwhal, we don't know if it could produce viable offspring, but both narwhals and belugas have 44 chromosomes. In fact, it may be possible for these post-zygotic barriers to change on a time scale of hundreds of thousands or millions of years. Pre-zygotic barriers, on the other hand, can change in the relative blink of an eye the pre-zygotic barriers that separate polar bears and brown bears. bears are behavioral isolation and habitat isolation. Brown bears live on land and polar bears live on sea ice.

Some ice remains year-round in the Arctic and provides vital habitat for wildlife such as seals and polar bears, but sea ice persists in the Arctic for more than a year. has been disappearing rapidly since the 1970s when satellite records began, we know it has been declining at a rate of about 13 percent per decade and this is bad news for polar bears because the sea ice was a hunting ground for polar bears when polar bears diverged from brown bears 150,000 years ago the last ice age was coming to an end speciation occurred when a population of brown bears followed the retreat of the ice

north

ward and adapted specifically to their new home in the Arctic their home is disappearing and they do not adapt well to anything but with no other option, they are forced to go south towards lands where they can search for seabird eggs on caribou, although not always with much success, and as they Polar bears are forced to move

north

, driven by increased human construction and development, these two types of bears are increasingly interbreeding. and prezygotic barriers are beginning to dissolve for other animals such as narwhals and belugas.

Changes in sea ice patterns may also be affecting their mating behaviors. However, both whale species breed at a time of year when thick sea ice prevents research ships from entering. In reality, we don't know much about what exact pressures may be spurring the existence of foreign narlugas. We can see how circumstances can bring certain animals together, but besides just an increase in chance encounters, there may be a deeper reason why hybrids are appearing in the world. In the world, more and more, with new species, new survival tactics are emerging. Some, like narlugas, create their own ecological niche, one that is different from their parents.

Belugas have 40 teeth, for example, and narwhals have none. Narlugas split the difference with 18 and, like a beluga. Narlugas have small teeth, but like a narwhal's tusk, these teeth are crooked and this is believed to be the reason why narlugas do not eat the same food as their parents, such as the fish, octopuses and shrimp they eat. They are found in the middle of the water column, but they feed with legs. from the ocean floor like walruses do as environments change, this new ability could unlock an underutilized food resource in that area Pili also have advantages that their parents don't Polar bears are struggling to survive without their hunting grounds common and their population increase is expected to decline by more than 30 percent in the next 30 years, their skulls and teeth are built for a very specific food source that is difficult to find in their new home, pisley fat, so On the other hand, it may have inherited some useful traits from grizzly bears that can eat virtually anything Grizzlies are formidable scavengers with diets consisting of insects a variety of plants Roots tubers grasses berries rodents fish transport along with other sources of meat generalist animals such as Grizzlies are the best survivors of rapid change in their environment.

They are not highly specialized top predators like polar bears, so inheriting these generalist traits could make pizzlies the new king in the north and this may mean that a lineage of Polar bears can only survive within hybridized pizzlies, even as pure polar bears are pushed closer to extinction in the near future. Another sad blow for polar bears, their hybrid versions. It may accelerate the decline of its purebred relatives, further competing with them and with hybrid offspring replacing the purebred offspring. The loss of polar bears is undoubtedly a terrible tragedy, but Pisley's case may be a necessary compromise given current warming trends, but as depressing as the polar bear's plight is, hybridization is not always a sad afterthought. resource, it can also increase biodiversity by creating more species, as in the case of African cichlids, these small fish hybridize like crazy and when two different species pool their genes the group becomes much larger, allowing for genetic variation among the descendants and soon leads to many new species.

The classical method of speciation, where genetic mutation gradually leads to one or two new species over many generations,

take

s a long time, but hybridization can create new species much faster. Just fifteen thousand years since Lake Victoria was formed, around 500 new species of cichlids have been created and hybridization is also part of our past. About sixty thousand years ago, our ancestors mated with two other now-extinct species of humans, Neanderthals and Denisovans, as their descent continued. to mate with our ancestors, their genes have been passed down to us through each generation. Now, in some populations, up to two percent of DNA comes from Neanderthals and up to six percent from Denisovans, this translates into hundreds of genes as scientists continue their research into hybrids.

Through fossil records and genetics, the tree of life we ​​often associate with the evolution of species seems increasingly less precise. Instead, we could imagine a web of life in which interbreeding and hybridization occur throughout the evolutionary process, generating new and sometimes improved ones. There is always so much going on in the world with the economy and climate change technology, but in the last few years I stopped watching or reading the news, it was too stressful to wake up and have people immediately arguing and yelling at me, so I stayed. in touch with the world I was waking up and scrolling through the usual social media platforms to see the latest news, but this also has a dose of terribleness and is not the best way to start the day, but I still wanted to be able to join in. in conversations about what Bitcoin is doing or how Jeff Bezos and company are floating in space and the answer I found to start my day and stay up to date is Morning Brew Morning Brew is a completely free curated newsletter delivered directly to you. in your inbox Monday through Sunday, gets you up to speed on business finance and technology in just five minutes without being dry or boring.

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