A Komodo dragon at London Zoo named Sungai laid a clutch of eggs in late 2005 after being separated from male company for more than two years. Scientists initially assumed that she had been able to store sperm from her earlier encounter with a male, an adaptation known as superfecundation. On December 20, 2006, it was reported that Flora, a captive Komodo dragon living in the Chester Zoo in England, was the second known Komodo dragon to have laid unfertilized eggs: she laid 11 eggs, and seven of them hatched, all of them male.

Scientists at Liverpool University in England performed genetic tests on three eggs that collapsed after being moved to an incubator, and verified that Flora had never been in physical contact with a male dragon. After Flora's eggs' condition had been discovered, testing showed that Sungai's eggs were also produced without outside fertilization. On January 31, 2008, the Sedgwick County Zoo in Wichita, Kansas became the first zoo in the Americas to document parthenogenesis in Komodo dragons. The zoo has two adult female Komodo dragons, one of which laid about 17 eggs on May 19–20, 2007. Only two eggs were incubated and hatched due to space issues; the first hatched on January 31, 2008 while the second hatched on February 1. Both hatchlings were males.

Komodo dragons have the ZW chromosomal sex-determination system, as opposed to the mammalian XY system. Male progeny prove that Flora's unfertilized eggs were haploid (n) and doubled their chromosomes later to become diploid (2n) (by being fertilized by a polar body, or by chromosome duplication without cell division), rather than by her laying diploid eggs by one of the meiosis reduction-divisions in her ovaries failing. When a female Komodo dragon (with ZW sex chromosomes) reproduces in this manner, she provides her progeny with only one chromosome from each of her pairs of chromosomes, including only one of her two sex chromosomes. This single set of chromosomes is duplicated in the egg, which develops parthenogenetically. Eggs receiving a Z chromosome become ZZ (male); those receiving a W chromosome become WW and fail to develop.

It has been hypothesized that this reproductive adaptation allows a single female to enter an isolated ecological niche (such as an island) and by parthenogenesis produce male offspring, thereby establishing a sexually reproducing population (via reproduction with her offspring that can result in both male and female young). Despite the advantages of such an adaptation, zoos are cautioned that parthenogenesis may be detrimental to genetic diversity.


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To most humans, being male or female implies a certain set of inseparable biological and sociological characteristics, but the natural world around us is rarely so black and white. For every characteristic that we associate with a particular sex, the animal kingdom harbors at least one surprising exception; concepts that we believe are inextricably linked are uncoupled, and even reversed, in other species.

Our sex exerts an incredible influence on our lives, influencing anatomy, appearance, behavior, and countless other traits. Socially, our sex also matters in terms of how we are understood and treated by others, because we see each other through a gendered lens. Female college graduates are hired more often than male graduates, for instance, but earn 17 percent less than their male counterparts. Police pull male drivers over at a much higher rate than they do female drivers. In high school math classes, teachers direct questions toward, call on, and interact with male students much more frequently than females.

We tend to recognize differences between males and females and try to explain them as a function of sex; we classify some things as masculine and others as feminine, often couching these divisions in evolutionary terms. But these justifications are often inaccurate. As we'll see below, many of the sociological differences between males and females have little, if any, universal relationship to sex.

“Sex” vs. “gender”

Most humans make no real distinction between the words “sex” and “gender”—one term often replaces the other. When asking about a friend’s pregnancy, we might ask about either the sex or the gender of the baby with the same intent, and the US Census Bureau even uses the words “sex” and “gender” interchangeably. The general confusion between these terms made headlines recently when a transgender contestant wanted to compete in the Miss Universe Pageant; a kerfuffle ensued when nobody could quite figure out if that should be allowed.

Sex is a scientific concept, referring to the biological and physiological differences between males and females. In humans, males have penises, an X and a Y chromosome, and generally lower voices and higher amounts of body hair. Vaginas, two X chromosomes, and the ability to lactate and to menstruate are sex characteristics usually belonging to females. These traits aren’t universal in males and females of other species, but they are representative of the biological concept of sex.

Confusion over sex and gender norms runs rampant. Scientists tend to assign traditional human gender roles to animals—and even to plants.

Gender, meanwhile, is a sociological construct. Most often, the term “gender” describes how men and women fulfill certain cultural norms defined by their sex. The World Health Organization says that gender “refers to the socially constructed roles, behaviors, activities, and attributes that a given society considers appropriate for men and women.” Gender encompasses everything from preferences to hobbies to roles in the home and the workplace, and the term applies only in a human context; since it is a social concept, gender does not apply to other species.

That's not to say that cultural gender roles have no roots in biology. The tendency for women to take on many of the parental duties, for example, likely stems from mothers’ ability to lactate, providing necessary nourishment for their children. Biologically, men are drawn to a woman’s hourglass figure because it signals health and fertility; many women, in turn, try to alter or enhance their body shape to fulfill this standard of beauty.

However, ties to biology are not necessary for gender roles to develop, and many of these roles have nothing at all to do with sex. For instance, we often associate girls with pink and boys with blue. But it was standard in the US during the early 1900s to dress American boys in pink and girls in blue. With its hint of "powerful" red, pink was considered a “stronger” color, while blue was thought to be “daintier” and more suitable for girls. These preferences changed in the mid-20th century; today, many parents wouldn’t dare dress their sons in pink.

Because gender roles are so pervasive in human culture, we tend to use them to help us understand the rest of the world. Unfortunately, viewing nature through a human lens doesn’t always give us an accurate picture of what is going on. Nature constantly engineers new and creative solutions to all sorts of problems—turning our stereotypes about sex upside-down along the way.

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The Images Below:
        Humon, the artist behind the webcomic Scandinavia and the World, uses cartoons to explain animal mating habits that fall outside the bounds of "traditional marriage" by anthropomorphizing the players in her trademark adorable style. In her animal gender roles series, she takes a similar approach, portraying various animals as humans so that we can imagine how their family and mating structures might look among our own species.

Read More: http://www.comicsalliance.com/2012/04/14/animal-gender-roles-cartoons-humon/#ixzz28NuPl4cR