• Polyploidy: A condition in organisms where there are more than two complete sets of chromosomes.
• Autotetraploid: A tetraploid (organism with four sets of chromosomes) that has all its sets from the same species.
• Allotetraploid: A tetraploid that has its chromosome sets from two different species.

Polyploidy in plants is like a plant version of getting an extra copy of a book. This occurs due to the duplication of chromosomes without a following cell division, a case of 'buy one, get one free' at the cellular level. The result? A whole-genome duplication!

Real-life example 🌎: Our friend, the sand rock-cress (Arabidopsis arenosa) comes in two forms: diploid (16 chromosomes) and autotetraploid. Picture the diploids as rock band groupies hanging out in Eastern and Southeastern Europe. Then, some got a chromosome boost becoming autotetraploid, and like adventurous roadies, they hit the road, spreading to Western Europe and Scandinavia.

An autotetraploid plant is like a clone army of chromosomes – all four sets of homologous chromosomes come from the same organism. However, this can lead to fertility issues as mis-pairing during meiosis becomes a likelihood. Over time though, the plants can adapt, allowing these clone armies to flourish!

Real-life example 🌎: Returning to our Arabidopsis arenosa example, these plants are a perfect case of overcoming adversity. Initially, they had low fertility due to mis-pairing during meiosis, but eventually, genetic changes allowed these autotetraploids to establish successful populations.