How does parthenogenesis differ from sexual reproduction?

Parthenogenesis differs from sexual reproduction as it involves the development of an egg into an offspring without fertilisation.

Parthenogenesis is a form of asexual reproduction where an egg develops into a new individual without being fertilised by a sperm. This is in stark contrast to sexual reproduction, which requires the fusion of male and female gametes (sperm and egg) to produce offspring. The offspring produced through parthenogenesis are genetically identical to the parent, barring any mutations, as they inherit their genetic material from a single parent.

In sexual reproduction, the offspring are genetically diverse as they inherit a combination of genetic material from both parents. This genetic diversity is a result of the process of meiosis, where the number of chromosomes is halved and genetic material is shuffled to produce unique gametes. This is not the case in parthenogenesis, where the offspring are produced from unfertilised eggs that have not undergone meiosis, and therefore have a full set of chromosomes from the mother.

Parthenogenesis is common in many invertebrates such as bees, wasps, and aphids, and some vertebrates like certain species of fish, reptiles, and birds. It is a strategy often used when sexual reproduction is not possible due to a lack of males, environmental conditions, or other factors. However, it does limit genetic diversity, which can make a population more susceptible to diseases and less adaptable to environmental changes.

On the other hand, sexual reproduction, despite being more energy-intensive and requiring two parents, is the most common form of reproduction in higher organisms, including humans. It provides the advantage of genetic diversity, which can increase a population's ability to adapt to changing environments and resist diseases.

In summary, while both parthenogenesis and sexual reproduction result in the production of offspring, they differ significantly in their mechanisms and outcomes. Parthenogenesis involves the development of an egg without fertilisation, resulting in genetically identical offspring, while sexual reproduction involves the fusion of male and female gametes, resulting in genetically diverse offspring.