![]() Two X chromosomes, the primary sex-linked genetic storehouse, give rise to only female offspring.īut on rare occasions, animals such as aphids can produce fertile male offspring that are genetically identical to their mother except for lacking a second X chromosome. This form of parthenogenesis is more common in plants.įor most organisms that reproduce the first way, through automixis, the offspring typically gain two X chromosomes from their mother. Because these cells never undergo the gene-jumbling process of meiosis, offspring produced this way are clones of their parent, genetically identical. In another form of parthenogenesis, apomixis, reproductive cells replicate via mitosis, a process in which the cell duplicates to create two diploid cells-a kind of genetic copy-and-paste. This process, which has been documented in sharks, slightly shuffles the mother’s genes to create offspring that are similar to the mother but not exact clones. In one version of parthenogenesis called automixis, an animal can merge a polar body with an egg to produce offspring. The process of meiosis also creates a byproduct: smaller cells called polar bodies, distinct from the fertile egg. (These are called haploid cells cells that contain two chromosomal copies are called diploid cells.) These eggs contain only half the mother’s chromosomes, with one copy of each chromosome. Ovaries produce eggs through a complex process called meiosis, where the cells replicate, reorganize, and separate. But in parthenogenesis, the body finds a unique way of filling in for the genes usually provided by sperm. Each provides half the genetic information necessary to create a living organism. Sexual reproduction involves two ingredients: an egg cell and a sperm cell. Parthenogenesis comes from two Greek roots that literally translate to “virgin creation.” How it works And in 2006, at England’s Chester Zoo, a Komodo dragon named Flora achieved a similar feat, puzzling keepers. Examples include a zebra shark named Leonie, housed with other female sharks at Australia’s Reef HQ Aquarium, who stunned her keepers in 2016 when three of her eggs hatched into living pups.Ī few years earlier, at Louisville Zoo, a reticulated python named Thelma-who had never even seen a male python-laid six eggs that developed into healthy young snakes. Such events can shock those who care for the animals. The process, called parthenogenesis, allows creatures from honey bees to rattlesnakes to have so-called “virgin births.” But a small subset of animals can have offspring without mating. Why birdsong evolved remains a major question, although the functions of song memorisation could shed light on this problem.The vast majority of animals need to breed to reproduce. ![]() ![]() Besides, avoiding inbreeding and finding a local mate could be functions of song memorisation as well, but further research needs to clarify this.Ĭoncluding, to some extent, recognition and mate choice seem to be functions of song memorisation. ![]() Females learn to prefer songs of tutored males of their own subspecies by memorising songs. Furthermore, song memorisation in female zebra finches could play a role in mate choice. It is shown that female zebra finches are able to recognise conspecifics, their own subspecies and their mate. We explored the functions of song memorisation in recognition and female mate choice. We discussed the functions of song memorisation in female zebra finches based on current literature. However, female zebra finches do not sing, and therefore song memorisation in females must serve other purposes. Males use memories of songs in order to develop an own song. Zebra finches are able to memorise songs, this takes place both early in life and throughout life. Memorisation brings along costs, therefore certain benefits must outweigh these costs. ![]()
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