Have you ever wondered if there are animals that reproduce asexually? Sexual reproduction is by far the most common breeding method in the animal kingdom. It has been estimated that about 99% of all multicellular organisms have sex in one form or another. The ability to recombine DNA from two completely different genomes is so prevalent that it should offer multiple benefits to offspring.
But the science of sex is known for its cunning; there are several explanations for how it came about. One hypothesis is that sex has evolved as a kind of genetic sorter; this increases the likelihood that the offspring will inherit a good mix of beneficial genes from both parents. Another hypothesis is that sex helps to get rid of harmful mutations or changes in the genome. Another hypothesis is that sexual reproduction allows organisms to better fight disease; thanks to improved genetic variability, offspring can “patch” exploited vulnerabilities. Most likely, sex arose as a result of the combination of all these factors.
In contrast, asexual reproduction eliminates all genetic sorting. While sexually reproducing animals must spend a lot of time and energy finding and grooming a potential mate, asexually reproducing animals can create new offspring, even identical clones, with incredible speed and ease. Lack of genetic diversity is a huge loss, but under certain circumstances it can be very beneficial.
Parthenogenesis, in which an unfertilized egg grows into a new individual without the need for sperm, is one of the most common forms of asexual reproduction in the animal kingdom. Has been observed in about 70 species of vertebrates as well as many other invertebrates. Some of these species will be listed below. It should be noted that asexual behavior should not be confused with hermaphrodite animals such as snails and earthworms, which have both male and female reproductive organs but otherwise reproduce sexually.
# 10 Asexually reproducing animal: sharks
It was believed that these formidable marine predators reproduce exclusively sexually. But recently, scientists have documented several breeding cases of captive female zebra sharks and hammerhead sharks in the absence of suitable males. Subsequent DNA tests showed that his genome was identical to that of his mother, which ruled out the already unlikely possibility that they had stored male sperm for several years. This form of asexual reproduction of animals is probably not very common in the wild because it reduces the amount of genetic diversity available to offspring, which can eventually lead to inbreeding over several generations. However, in times of reproductive deficiency, it is probably beneficial.
# 9 Animal that reproduces asexually: Komodo dragons
The Komodo dragon, which is about 10 feet long and weighs about 300 pounds, has been extensively studied for its interesting physiology and behavior. But for a long time, no one even suspected that they had the ability to reproduce asexually, until two lonely females became pregnant at Chester’s London Zoo in 2006, which spurred scientific news. This form of asexual reproduction is achieved with a clever trick. Usually, during sexual reproduction, female dragons create four “pre-ovarian” cells. One of them will become an egg, while the other three will be absorbed back into the body. But when a female produces asexually, one of those unused eggs can become a kind of surrogate sperm that brings genetic material into the actual egg.
What’s even more interesting about this particular form of asexual reproduction is that babies are not exact clones of the mother. They cannot be exact clones because all offspring are males. This is due to a unique feature of Komodo genetics. While males inherit two different types of sex-determining chromosomes (called XY chromosomes), the opposite is true for Komodo dragons. Two copies of a chromosome create a male dragon. Think of the sex chromosomes in terms of the letters Z and W. The combination of ZW produces a female, ZZ produces a male, and WW produces an unviable egg. Basically, since each egg is genetically identical, they can form combinations of ZZ or WW chromosomes, but not ZW when they come together, so all viable offspring are males.
What adds to the intrigue of this story is that the rule of World War cannot be set in stone. In 2010, it was discovered that the boa constrictor can produce offspring of WW females in a similar manner asexually. Previously, this was considered impossible. If this is not a rare coincidence, the result suggests that asexual reproduction in snakes and other reptiles may be more difficult than previously thought.
# 8 Asexually reproducing animal: Whiptail lizards
Whiptail is a family of lizards, most of which are native to America. At first glance, they look no more remarkable than ordinary reptiles, but thanks to years of painstaking research, we now know that some species are 100% female and have an amazing ability to reproduce asexually. This is not just a trick or a backup strategy; it is their main breeding ground.
They were probably created as a result of hybridization of two related species. Although hybrids are usually sterile, they can sometimes develop rapidly as a means of asexual reproduction in order to survive. The main obstacle to full-fledged parthenogenesis is the need to create a complete set of chromosomes in the absence of fertilization from a sexual partner. But some canines do cross this barrier, probably in one generation.
While real sex never occurs, females seem to engage in courtship rituals and bond with each other, which appears to stimulate the fertilization process. However, without the emergence of any new genetic variation, it is unclear whether these species will be able to adapt well to changing environments or circumstances. Their genomes are mostly static.
# 7 Animal that reproduces asexually: aphids.
Aphids are a family of soft-bodied insects that suck sap from the stems and leaves of plants. For many aphid species, the most common strategy is to alternate between asexual reproduction in the summer (which allows them to quickly colonize new plants) and sexual reproduction in the fall and winter to obtain the next generation. Asexual offspring are usually genetically identical to the mother, which means that they are all born to females. Sexually produced offspring can be either male or female.
# 6 Animal that reproduces asexually: Amazon mollies
This exclusively female species of freshwater mollies has developed a unique form of asexual reproduction. The name itself is a reference to a community of female warriors from Greek mythology, and not to the famous river habitat (in fact, they live in the Rio Grande and Tuspan rivers near the Mexican-American border). What is truly unique about the Amazonian mollie is that it does mate with the opposite sex, but only with a male from a closely related species. Sperm is not used to fertilize an egg or provide any genetic material; after all, it’s a different kind. Instead, its sole purpose is to get the egg to start developing. It is not entirely clear why this happens and how it avoids the problem of genetic diversity. The species is estimated to have reproduced in this way for 100,000 to 200,000 years, far above the normal expectation point, so there must be some way for it to maintain genetic variation.
# 5 Animal that reproduces asexually: turkeys and chickens
Parthenogenesis is quite rare in birds and mammals. But as early as the 19th century, people began documenting rare cases where poultry developed from unfertilized eggs, and they all became males. Based on later analysis, it is estimated that only about one percent of them actually survive to become chickens, which is obviously not enough to affect genetic diversity, but humans have managed to create a new strain of domestic turkey with a higher survival rate for unfertilized eggs.
# 4 Animal that reproduces asexually: marble crayfish.
Marble crayfish are one of the strangest evolutionary examples of recent memory. It was believed that this purely asexual animal first arose as a result of a strange mutation of one species in captivity in 1995. Soon, this new organism was given to many other owners, some of whom released them back into the wild, where they quickly spread and drove out some of the locals. crayfish even to Madagascar. Marble crayfish are so successful in creating new populations that they are banned in the United States and the European Union.
In part, this makes it unique in the fact that marbled crayfish are the only known decapod crustaceans that reproduce asexually, creating identical copies of their parent. This animal has an amazing 276 chromosomes or three sets of 92 chromosomes. In contrast, humans have only 46 of them. There is a theory that it originated in the wild, but based on genetic analysis, it has been suggested that the marbled crayfish was created in captivity as a result of the mating of two crayfish that originated in different regions of the world; one of his parents could have two copies of the same chromosomes, which gave him just three. This was followed by further genetic modifications that made him asexual.
# 3 Animal that reproduces asexually: bees and wasps
Some species of bees and wasps have the ability to produce unfertilized eggs, which eventually develop into males. But the Cape honey bee is one of the few known species that can also produce new females through parthenogenesis.
# 2 Animal that reproduces asexually: sponges
Sponges are among the most basic organisms in the animal kingdom, so it should come as no surprise that many of them reproduce asexually. The main strategies are to grow a new copy directly from its own body, such as a kidney, or to produce a mass of new cells called gemmules.
# 1 Animal that reproduces asexually: stick insects
Like aphids, many stick insects are able to switch between sexual and asexual reproduction depending on the circumstances. Parthenogenesis will only lead to the appearance of female copies, so at some point in his life he still needs sexual mating. The common Indian stick insect, which is so often kept as a pet, is largely parthenogenetic in nature.
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