The Village Naturalist

The term “gender” has been in the news a lot, with the question of just how many genders are there?

Gender is not sex. Here is a quote from the National Institute of Health on the difference between gender and sex. “Sex is a biological fact, gender is a social and cultural construction.” Sex refers to the genetic component of the individual along with the secondary sex characteristics, the hormones produced, and the production of gametes…eggs or sperm. Seems simple, right? Nope. Sexual reproduction, all by itself, can get really complicated even without all the social sexuality issues.

Let’s start with “Parthenogenesis”. This is the process of an unfertilized egg developing into an adult.

This is common in insects, think honeybees. The fertilized eggs all hatch into female worker bees, and when the queen runs out of fertilized eggs, the unfertilized eggs still develop; they develop into males.

A second example (and there are over 2,000 known examples) is the New Mexico whiptail lizard. There are no known male New Mexico whiptail lizards! The females lay the eggs; the eggs develop without having been fertilized, and the new lizards hatch, all females.

For Komodo dragons, if no males are around, the female will lay unfertilized eggs, which all hatch out as males.

The next complexities in sexual reproduction are those animals that are hermaphrodites. These are both male and female. The first example here is the common earthworm. While they contain both sex organs and produce both sperm and eggs, they cannot self-fertilize, so they still have to find a mate.

The same is true for the common pond snail. If a pond snail runs into another member of its species, they cross-fertilize and then both produce eggs. This maximizes their chances for producing a large number of offspring that have a variety of different genetic blends. This ensures that some will generally be able to survive regardless of any environmental conditions. It works. Pond snails may be one of the most prolific animals on earth! However, being hermaphroditic can confuse your family lineage. As one writer put it, “Imagine, your sister’s mom is your dad and her dad is your mom!”

There are over 65,000 known species that are hermaphroditic, though most are insects, and then there are some that, while technically hermaphroditic, are either male or female for a time, and then they change! This occurs mostly in fish. In some fish all the young start out as females. As they grow they eventually change into males. It is believed that the small size provides a means of safety for the females.

They produce eggs, which the much, much larger male spawns and he then protects both the female and the eggs. The females eventually grow large enough and change into males. These fish are called “protogynous”, or female first.

In the movie “Finding Nemo” a male clown fish, Marlin, loses his mate to a barracuda and then he loses his son, Nemo, to a SCUBA diver who puts Nemo into a fish tank. Marlin then goes on a quest to find Nemo. In real life when a male clown fish loses a mate, they transition into a female clown fish that can then attract a new male to “her” anemone. Fish that start out as male and transition to females are called “protandrous” or male first.

This all seems way too complicated and you would think that “nature” would be better off if, instead of sexual reproduction, all organisms just reproduced asexually…but then, where would the fun be in that?