How come alligators and crocodiles can’t make viable offspring? Isn’t the only difference between the two the snout?
In: 3
The snout is just the most visible feature. If you look at them carefully they are different colors, their eyes are placed differently in the skull, their shells are different, the body have different shape, etc. Although these are more subtle then the snout shape. Saying that the only difference between crocodiles and alligators is the snout is like saying the only difference between humans and gorillas is the body hair.
Guess we can’t expect gators and crocs to have a ‘crocodog’ anytime soon. Nature’s just picky like that! 🐊🐊🐶
In genetics there are concepts of genotype and phenotype.
**Phenotype** refers to how creatures *look* – on the basis of the instructions contained in their genetics. The expression of their genes.
**Genotype** refers to what the actual genetic information (DNA) contains. The code or blueprint for the animal if you will.
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The alligator and crocodile are *phenotypically* very similar – they look like the same thing with a few minor differences.
*Genotypically*, they are too different to interbreed. That is to say their genetic code is too distinct from each other, or is organized in incompatible ways.
They don’t have the same number of chromosomes, even different species of crocodiles have different numbers and can’t interbreed, there is a lot more that is different than the nose.
Here’s an analogy: How come I can’t take half the parts from a Honda Accord and half the parts from a Ford Fusion, and build a working car? They’re both 4-door sedans, and the only difference between the two is the brand on the front, right? Unfortunately, no. Even though both of them are trying to do the same job of “be a car”, and they both are based on the same original car (Model T or something similar), they’ve been gradually accumulating differences ever since they both split. Each of their new years’ models are based off making changes to their own previous model. Similar structure, but a lot of small differences means that most of their parts are probably not compatible without a lot of tweaking and customization.