Janet L. Over the last years, research has established that a sexual selection exists and is widespread in the plant and animal kingdoms; b it does not necessarily entail sexual dimorphism; even hermaphrodites have it; c it does not require intelligence or a sophisticated sense of esthetics; even tapeworms and plants choose mates; and d it does not require brawn or even mobility for competition; plants may compete for pollinators, and broadcast spawning invertebrates may also compete for matings. Although discussions of sexual selection often focus on sexual dimorphism, several phenomena that are commonly associated with sexual selection are widespread and highly developed in hermaphrodites. These phenomena include a bizarre and expensive courtship and copulatory behavior, b multiple mating and sperm competition, c rapid evolution of genitalia, d special structures associated with courtship, and e sexual polymorphism. The skewed breeding sex ratios associated with sequential hermaphroditism have long been recognized as contributory to sexual selection.
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For example, the great majority of tunicates , pulmonate snails, opisthobranch snails , earthworms , and slugs are hermaphrodites. Hermaphroditism is also found in some fish species and to a lesser degree in other vertebrates. Most plants are also hermaphrodites. Historically, the term hermaphrodite has also been used to describe ambiguous genitalia and gonadal mosaicism in individuals of gonochoristic species, especially human beings.
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Siphotperon sp. A simultaneous hermaphrodite, the slug has both male and female reproductive organs that it uses simultaneously during sex shown here. For its male organ, the slug has a two-pronged penis consisting of a penile bulb that transfers sperm, and a separate, needlelike appendage called a penile stylet that stabs and injects partners with prostate fluid-containing sex hormones called allohormones. Here, a reciprocal copulation between the sea slugs with both penile stylets pst inserted into the mating partners' foreheads h ; the penile bulbs pb are inserted in the mating partners' female genital openings hidden behind the right parapods pa. The close-up photograph of a reciprocal copulation c shows the penile stylet of the left individual inserted into the forehead of the right individual.
Named after King Amanullah Khan, it is said to be the first, the biggest and the most modern city in the history of Afghanistan. Jalalabad is considered the capital of Afghan cricket, with many of the national players coming from the surrounding areas. It is hoped that this ground will serve the domestic competition and attract international teams. A large reservoir near Sarobi, located on the way to Kabul. Hada Museum south of Jalalabad contains exhibits related to pre-Islam period.