🌿 1.8 – Species and Speciation
🧬 What is a Species?
A species is one of the most important ideas in biology. But what exactly is it?
A species is a group of living organisms that:
- Can breed with each other naturally
- Produce fertile offspring (their babies can also have babies)
🧠 Example:
A dog and a cat cannot mate and produce puppies or kittens together. Why? Because they belong to different species.
But two dogs (even different breeds like a Pomeranian and a German Shepherd) can mate and produce puppies. So, they are different breeds of the same species.
🔍 Problem in identifying species
Sometimes, animals or plants look very similar but are genetically different – these are called cryptic species.
Cryptic species: They look the same but are different species on the inside (genetically).
🧠 Example:
Two butterflies may look identical, but if they can’t produce fertile offspring, they are considered different species.
👨🔬 Ernst Mayr’s Biological Species Concept
German-American biologist Ernst Mayr said that the best way to define a species is through reproductive isolation.
Reproductive Isolation means that members of different species:
- Cannot or do not interbreed
- Or if they do, they produce infertile offspring
🧠 Example:
A horse and a donkey can mate and produce a mule. But a mule is infertile, so horses and donkeys are different species.
🔑 Mnemonic to Remember ‘Species’ Concept
📘 “Same Genes, Same Kids”
- Same Genes: They share similar DNA
- Same Kids: They can have babies that can also have babies
This reminds you that a species can interbreed and have fertile offspring.