As temperatures rise and the overlap of species' range of activity, hybrid offspring of brown bears and polar bears (called gray-white bears or polar grizzly bears ) may become more common. Photography: PHILIPPE CLEMENT, ARTERRA, UNIVERSAL IMAGES GROUP, GETTY
Written by: JASON BITTEL
In the summer of 2020, Pennsylvania scientists discovered an unprecedented bird: it looks like a rose-breasted white spotted finfinch, but its singing throat is similar to the scarlet Tangerine.
After more careful analysis, the bird was later identified as a hybrid species and was the offspring of two different species of individuals.
Ornithologist Bob at Pittsburgh National Bird Park Mulvihill recalls: "I was amazed when I saw it, 'Oh my god!'. Mulvihill caught the bird and extracted blood samples to study the genes of the hybrid animal.
Some hybrid animals are well known, such as mules, but the bird is notorious because the two parent species have different colors. The rose-breasted white spotted finch is black and white with a red patch on its chest, while the scarlet tanner's feathers are bright orange and black.
Before 2020, scientists have never recorded a hybrid between the rose-breasted white spotted finch (above, a rose-breasted white spotted finch at Columbus Zoo) and the scarlet tanner. Photo by OEL SARTORE, NATIONAL GEOGRAPHIC PHOTO ARK
These two birds are not distant relatives, nor close relatives. Mulvihill suspects that the two species may have been separated due to more than 10 million years of divergent evolution.
What’s even more strange is that the two species coexist in most parts of North America, which raises researchers’ questions about why no one has seen evidence of the two hybrids before.
html l3 "Is this just a special case like Romeo and Juliet?" he said with a smile.
Nowadays, with the emergence of gene sequencing and gene analysis technologies, hybrid animals have also made new meanings. They may have clues to solve the mystery of evolution.
Scientists recently confirmed that there are seven different spotted skunks in the Americas, such as the eastern spotted skunk (as shown in the picture). Photo by JOEL SARTORE, NATIONAL GEOGRAPHIC PHOTO ARK
What is a hybrid animal?
Evolutionary biologist Erica at the University of Denver Larson says that from genetics, hybrid animals are the result of hybridization between individuals of different species.
Most non-scientists would think that this means reproduction between two different species, but it can also include subspecies or even populations within a species that can be distinguished from each other according to certain traits or traits.
"They may reproduce at different times of the year, or their behaviors make them less likely to mate," Larson said. "But if they do mate, they may give birth to hybrid offspring that are completely unproblematic." "
One example of this is the spotted skunk, which scientists recently divided into seven species, some of which look almost the same, live in the same areas, but have several months apart in mating and production.
"Another good example is the coral ," Larson said. "Many corals release gamete at a very specific time. So all these species are physically in the same place, maybe they can form a hybrid," but their reproduction time is a few hours or days apart, thus missing the opportunity to generate hybrids.
However, in captivity or labs, these natural obstacles have less obstacles to successful hybridization.
A Lion Tiger beast at Taman Safari, West Java, Indonesia, is a hybrid offspring of a male African lion and a female tiger. Photo by JOEL SARTORE, NATIONAL GEOGRAPHIC PHOTO ARK
Which animals can hybridize?
One of the most famous hybrid animals is the so-called lion and tiger beast, the hybrid offspring of male lion and female tiger.A 2004 movie "HTM3 Big Name Napoleon " brought the lion and tiger beast into the public eye. But few people have heard of tiger lion beast , the offspring of female lions and male tigers. The two pairings of
are almost impossible to happen in wild environments, because the range of movement of lions and tigers almost never overlaps. The same is true for hybrid camel , which is a hybrid offspring of lappa and dromedary camel. Both live on both ends of the Atlantic Ocean, but have been bred by researchers.
Equators are particularly prone to hybridization. Donkeys and horses can breed mules, while zebras and horses can breed hybrid zebras or other combinations.
In 2019, scientists first proved that narwhal sometimes hybridizes with beluga, producing narluga. There are also at least 20 reports on the hybrid offspring of various dolphins and whales in wild and captive environments.
This situation does not exist only in mammals. There are also records that there are also hybrids between wood grain rattlesnake and western rhombus rattlesnake , Cuban crocodile and American crocodile, Russian sturgeon and spoon sturgeon , Clark hemp salmon and rainbow trout , as well as various insects, such as ant , bees, wasp and termites. Plants have particularly strong hybridization capabilities and are considered to be higher than animals' hybridization rates.
One of the most numerous hybrid species on Earth is probably modern humans, carrying genetic signs of hybridization with other ancient humans, such as Neanderthal and Denisovan .
2002, the camel breeding center in Dubai , Kamilah stood next to her mother, Kamilah is a hybrid offspring of male dromedary camels and female llamas. Photography: REUTERS, ALAMY
Is animal hybridization rare?
Although hybridizations look unusual, many of them are very common.
For example, Mulvihill said there are a large number of hybridization records in birds, and of more than 10,000 known species, up to 10% of species are hybridized. This may not be a coincidence, as a large number of birdwatchers took pictures of these interesting sights and posted them on smartphone apps such as forums, birdwatching association pages, or iNaturalist.
"It is well known that hybridization is also common among butterflies," Mulvihill said. But unlike birdwatchers, few butterfly observers can easily detect signs of hybridization of this insect.
Some scientists also believe that certain hybrids may become more common in the future. For example, as climate change reduces Arctic sea ice, polar bears are expected to spend more time on land, where they may encounter brown bears expanding northward. If they mate, they can create hybrids called Arctic grizzlies or grey bears.
In 2013, a hybrid zebra cub frolicked on a farm in Coochery, France. It is a hybrid offspring of a male zebra and a full horse. Photography: ALAIN JULIEN, AFP, GETTY
Is animal hybridization good or bad?
hybridization does not always indicate genetic bad luck. But it may not produce more powerful species, either.
For example, lions and tigers are prone to health problems, such as rapid growth and heart problems.
In addition, there may be incompatible genetic differences in parent species, such as differences in the number of chromosomes. This is one of the reasons hybrids are usually infertile, and a progeny that cannot reproduce will limit the parents' success in expanding their gene library .
"They miss one chance to pass genes to offspring," Larson said.
If one or both of the parent species are in danger of extinction, hybridization will cause trouble. This is because when a species' genes become rare, new combinations of hybrid offspring replace it, threatening its survival. This is called genetic annihilation, which is why hybridization with coyote is one of the many threats currently plaguing red wolf in the southeastern United States.
However, hybridization can also introduce beneficial genes, such as insecticide resistance, Larson said. If these genes are beneficial to the survival and reproduction of hybrid offspring, this benefit will spread widely in the population. This is what scientists call adaptive infiltration.
"But I think most of the time, it may be neither good nor bad," Larson said. "Most of the time, it may not work."
With the advancement of genetic tools, scientists can now easily identify intruders that may have originated elsewhere by observing the genome of hybrids. This means that every hybrid is a window into how evolution creates new species.
"For example, there are two species whose genomes have undergone hundreds of thousands of years of independent evolution, and then you put them back together and mix these genomes in hybrid form," Larson said. "You can understand what works and what doesn't."
(Translator: Flowers on Mohang)
