Parthenogenesis Is a mechanism in which offspring are produced asexually. Lineages are generally comprised of all females and in theory, these species should have an advantage over their sexual counterparts because (1) there is no energy expended in searching for a mate and (2) each individual is capable of reproducing, so no energy is wasted on males in general. However, in reality, this does not appear to hold true since sexual reproduction is the most common form of reproduction among animals. Therefore sexual reproduction must provide substantial advantages to the organism in order to compensate for the increased energy required to produce males.An obvious advantage for sexual reproduction is the genetic diversity that results from the combination of gametes. This increased variation in sexual species allows for different selective advantages among individuals that aid in the long-term survival of the species. In contrast, parthenogenotes are thought to be genetically isolated and clonal, decreasing their chances for long-term survival in a changing environment. Most Aphids reproduce in this way. Aphids produce two different types of gametes depending on the environmental conditions and the time of year. In warmer regions all the aphids reproducing FEMALES during the spring and summer months. Thier gamates develop into small perfect copies of the parent without fertalisation. This process allows the whole population to produce young and therefore take full advantage of the plentiful supply for food and water. Towards the end of Autumn food becomes scarce and the weather tends to be cooler, this signals to the aphids to start to produce both male and female copies. these copies quickly mature and then fly off to mate sexually, this provides variance in the next set of offspring since they are not copies but a result of sexual mating in which traites from both parents are passed onto the offspring. this gives the offspring gentic variablitly. These parent lay eggs in the soil or in trees which lay domant until next spring when the weather is warmer and food more readily available again.
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