Phenotype vs. Genotype: What you see isn’t always what you get

When looking at a hedgehog or a tenrec, it’s tempting to assume that what you see on the outside tells the whole story. Colour, body type, behaviour, these visible traits are the phenotype. But behind every phenotype is the genotype: the actual genetic makeup that determines what traits an animal can pass on to its offspring.

For breeders and researchers, understanding the difference between phenotype and genotype is critical. It explains why two animals that look the same may produce very different babies, and why responsible breeding depends on more than appearance.

What Is Phenotype?

The phenotype is the collection of traits you can see, measure, or observe in an individual. Examples include:

• Spine or coat colour in hedgehogs
• Size and body weight
• Behavioural traits, such as activity levels or temperament
• In tenrecs, visible traits like body length, fur/spine pattern, or climbing ability

The phenotype is the result of genes interacting with the environment. For instance, a hedgehog may appear overweight (phenotype) due to diet and exercise, not genetics alone.

What Is Genotype?

The genotype is the set of genes that the animal carries in its DNA. Some of these genes are expressed directly in the phenotype, while others may remain hidden as recessive traits. Key points about genotype:

• Determines what an animal can pass to its offspring.
• May include recessive genes not visible in the phenotype.
• Can only be confirmed through breeding outcomes or genetic testing.

Why Phenotype and Genotype Don’t Always Match

Two hedgehogs may both appear cinnamon in colour (phenotype), but one may carry hidden recessive genes for albino, while the other does not. When bred, the results will differ dramatically depending on genotype, even if the parents look identical.

In tenrecs, most breeding focuses on maintaining healthy populations rather than colour traits. Still, hidden genotypes matter: recessive genes for health conditions may not be visible until two carriers are bred together.

Implications for Breeding

1. Colour breeding in hedgehogs

• Phenotype tells you what the animal looks like now.
• Genotype determines what colours or patterns might appear in the next generation.
• Without pedigree information, breeding outcomes are often unpredictable.

2. Health management

Some conditions, like Wobbly Hedgehog Syndrome (WHS), may be influenced by recessive inheritance. Animals can be healthy (phenotype) but still pass on genetic risk (genotype). Outcrossing and careful record-keeping reduce the risk of doubling up on hidden health issues.

3. Tenrec breeding

Even when external traits seem uniform, genetic diversity matters. Two unrelated-looking tenrecs might still share close ancestry if their genotype is not tracked; risking inbreeding depression.

In Summary

• Phenotype = what you see (visible traits).
• Genotype = the underlying genetic code (hidden and visible traits).
• What you see isn’t always what you get: an animal’s appearance does not reveal its entire genetic potential.

For hedgehogs, this explains why colour breeding requires pedigrees, and for tenrecs, why ancestry tracking is essential.

Understanding both layers is the foundation of responsible breeding, healthier populations, and realistic expectations.