Reproduction

Jenny, Jenny!! Something’s happening to one of my rabbits! She’s all bloated and she made a nest and won’t move. Huh, it looks as if this rabbit is about to deliver some little rabbits. But how could this happen?!

I thought all my rabbits were female?! That can’t be right! It looks as if one of Michael’s rabbits is actually male - two female rabbits cannot produce baby rabbits. But why not? For a female rabbit to have offspring, its sex cells — gametes — must combine — fuse — with a male’s gametes.

This can only happen if an adult female rabbit and an adult male rabbit, breed. When the male and female gametes fuse, they create new combinations of genetic material. So all of the new rabbits are completely unique, because there will be mixing of genetic material between the male and the female gamete. But they will have some characteristics of both parents. Rabbits aren’t the only ones that reproduce this way.

Humans, other animals, plants and most fungi reproduce this way too! Some plants, however, produce both male and female gametes, so they don’t need to ‘breed’ with another plant - they can self-fertilise. In this case, the new plants still have different characteristics compared to the parent plant, because there is still mixing of genetic material between male and female gametes. Whether organisms reproduce through breeding, like rabbits, or through self-fertilisation, like some plants, we call it sexual reproduction. But not all organisms reproduce sexually — there is another type of reproduction.

Let’s take a look at bacteria which are as a rule microscopic and single-celled organisms. Bacteria don’t have the ability to produce gametes, and they can’t reproduce sexually. Yet, they still do reproduce. How? They simply divide!

When one bacterial cell divides, it becomes two identical cells. This type of reproduction is called asexual reproduction. In asexual reproduction there is no mixing of genetic material, unlike in sexual reproduction. The genetic material of the parent is simply copied. Offspring are identical to the single parent that produces them.

However, mistakes can happen when the genetic material is copied in this way. A ‘mistake’ like this is then passed onto offspring, which makes such offspring slightly genetically different from the parent. Bacteria are not the only organisms that reproduce asexually — some other single-celled organisms, such as yeast, reproduce this way too. Even multicellular organisms can reproduce asexually — potatoes or strawberry plants, for example! Organisms that reproduce asexually can produce a lot of offspring in a very short period.

While not all living things reproduce in the same way, all of them have the ability to reproduce. Reproduction is one of the basic characteristics of all organisms! Why is reproduction so important? Reproduction increases the size of the population of a species and ensures that species doesn’t become extinct. Larger population size also means a species can spread across a bigger area.

And finally, reproduction, in particular, sexual reproduction, introduces variety into a species, by creating new combinations of genetic material. This variety means a population will have a wider range of characteristics. So if there is a change in the environment, there is a greater chance that some individuals will have characteristics that will help them survive. You know Michael, I’m looking forward to being an ‘aunty’ to these little rabbits! Now let’s find the male rabbit, so that we won’t have any more surprises in the future!