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New Mexico whiptail lizard: Difference between revisions
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The New Mexico Whiptail lizard cannot sexually reproduce because they are all females.<ref name=Hiskey>Hiskey, D. [http://www.todayifoundout.com/index.php/2011/05/the-new-mexico-whiptail-lizard-is-made-up-entirely-of-females/ New Mexico Whiptail Lizards are All Females] ''Today I Found Out''. Web. Accessed February 4, 2015.</ref>[2,3]<ref name=State_Symbols/>. However, these lizards, simulate reproduction by way of pseudocopulation (which is when they act out sexual intercourse). The whiptails of the genus Aspidocelis [5,6] are lizards, created by a hybridization of the western whiptail (A. Inornatus) [2,3]<ref name=State_Symbols/> and the little striped whiptail (A. tigris). Generally, crossbred species (like the mule) are typically sterile. However, the New Mexico Whiptail reproduces by a complex series of events (that appear like cloning) where it's eggs require no fertilization, and its offspring are nearly a genetic duplicate of the mother.<ref name=Hiskey/>[5, 6] | The New Mexico Whiptail lizard cannot sexually reproduce because they are all females.<ref name=Hiskey>Hiskey, D. [http://www.todayifoundout.com/index.php/2011/05/the-new-mexico-whiptail-lizard-is-made-up-entirely-of-females/ New Mexico Whiptail Lizards are All Females] ''Today I Found Out''. Web. Accessed February 4, 2015.</ref>[2,3]<ref name=State_Symbols/>. However, these lizards, simulate reproduction by way of pseudocopulation (which is when they act out sexual intercourse). The whiptails of the genus Aspidocelis [5,6] are lizards, created by a hybridization of the western whiptail (A. Inornatus) [2,3]<ref name=State_Symbols/> and the little striped whiptail (A. tigris). Generally, crossbred species (like the mule) are typically sterile. However, the New Mexico Whiptail reproduces by a complex series of events (that appear like cloning) where it's eggs require no fertilization, and its offspring are nearly a genetic duplicate of the mother.<ref name=Hiskey/>[5, 6] | ||
An interesting fact that is a part of the process: two females will act out having sex as if one was a male. This is believed to increase the fertility of these lizards as it assists in producing more eggs than in females who don’t go through this act. The lizard who acts in the traditional female role assumes an inferior position while the other female lizard who assumes a superior position (hence the term pseudocopulation). Remarkably, the Whiptail lizards who assume the "female role" end up producing larger eggs than the lizard acting out the male role.<ref name=Hiskey/> | An interesting fact that is a part of the process: two females will act out having sex as if one was a male. This is believed to increase the fertility of these lizards as it assists in producing more eggs than in females who don’t go through this act. The lizard who acts in the traditional female role assumes an inferior position while the other female lizard who assumes a superior position (hence the term pseudocopulation). Remarkably, the Whiptail lizards who assume the "female role" end up producing larger eggs than the lizard acting out the male role.<ref name=Hiskey/> | ||
This hybrid species, reproduces by laying eggs that have never encountered any sperm[5,6]. | This hybrid species, reproduces by laying eggs that have never encountered any sperm[5,6]. No external fertilization occurs [2,3] as a result of two closely related species mated to create asexual hybrids. [5,6]. This phenomenon shouldn’t work . | ||
Previously reptile researchers believed that the unfertilized eggs and hatchlings were clones of their mothers [2,3]<ref name=State_Symbols/>. However, this has now been disproven. The internal self- fertilization that does occur, does NOT produce perfect offspring clones. Recent research by doctoral student Aracely Lutes at Baumann Lab demonstrated that the New Mexico Whiptail lizard produces two times the number of chromosomes as other types of Whiptail lizards which mate normally. Lutes discovered that, this occurs as a result of a " process of recombination of these chromosomes, somewhat similar to what happens in normal male/female pairings, which then produces genetically diverse offspring."<ref name=Hiskey/> | Previously reptile researchers believed that the unfertilized eggs and hatchlings were clones of their mothers [2,3]<ref name=State_Symbols/>. However, this has now been disproven. The internal self- fertilization that does occur, does NOT produce perfect offspring clones. Recent research by doctoral student Aracely Lutes at Baumann Lab demonstrated that the New Mexico Whiptail lizard produces two times the number of chromosomes as other types of Whiptail lizards which mate normally. Lutes discovered that, this occurs as a result of a " process of recombination of these chromosomes, somewhat similar to what happens in normal male/female pairings, which then produces genetically diverse offspring."<ref name=Hiskey/> | ||
Generally, sperm and egg cells are created through a process called meiosis, (where a cell’s chromosomes are copied before the cell divides twice). This produces four daughter cells, meaning that the egg cells only contain half the amount of chromosomes of other cells. The joining of egg and sperm, that contain half the genes, helps balance out the chromosomes, to create the next generation [5,6]. | Generally, sperm and egg cells are created through a process called meiosis, (where a cell’s chromosomes are copied before the cell divides twice). This produces four daughter cells, meaning that the egg cells only contain half the amount of chromosomes of other cells. The joining of egg and sperm, that contain half the genes, this helps balance out the chromosomes, to create the next generation [5,6]. | ||
But the Whiptails are unique because they begin the process with two times as many chromosomes. Lutes, proved that these all-female whiptails have a slightly different type of meiosis. They double their chromosomes two times initially in the process, making eight copies | But the Whiptails are unique because they begin the process with two times as many chromosomes. Lutes, proved that these all-female whiptails have a slightly different type of meiosis. They double their chromosomes two times initially in the process, this results in the making of eight copies for each chromosome. In the normal two cycles of cell division, those copies are separated two each among the four daughter cells [5,6]. | ||
She measured the amount of DNA in the egg cells of two closely related whiptails, just prior to the first cycle of meiosis. She discovered in this stage, the chromosomes of the asexual checkered whiptail (A. tesselatus) make up two times as much as the sexual Texan spotted whiptail (A. gularis), despite the fact that both types have similarly sized genes. Microscopically, Lutes counted two times the usual number of chromosomes in the egg cells of the checkered whiptails [5,6]. | She measured the amount of DNA in the egg cells of two closely related whiptails, just prior to the first cycle of meiosis. She discovered in this stage, the chromosomes of the asexual checkered whiptail (A. tesselatus) make up two times as much as the sexual Texan spotted whiptail (A. gularis), despite the fact that both types have similarly sized genes. Microscopically, Lutes counted two times the usual number of chromosomes in the egg cells of the checkered whiptails [5,6]. | ||
Surprisingly enough, possessing eight sets of chromosomes instead of four is an easier process as they | Surprisingly enough, possessing eight sets of chromosomes instead of four is an easier process; as they do not require a lot for this to occur. This is the result of two processes. First, a cell can double its DNA but fail to divide into two, or two cells can fuse together [5,6]. | ||
== Ecology == | == Ecology == | ||
