Phylogeny: The history of organisms lineages as they change through time. (a phylogenetic tree is an evolutionary tree)
Recapitulates: In this case, the word means “appears to repeat through”
Ontogeny: The origin and the development of an organism – for example: from the fertilized egg to mature form.
In other words, by examining the ontogeny of an individual species, we can infer certain aspects of their evolutionary history.
Simply put, applying Occam’s razor, animals in development go through a cycle that indicates their ancestry. So one time we all had a tail. Vestigial but nevertheless a tail. We also had gill-slits during development. Life started in water: Development occurs inside a fluid filled uterus because that mirrors our ancestral lifestyle. You don’t breathe out your nose but from the umbilical cord.
What else provides evidence of biogenesis? What about physiology and cell structure?
Genetic similarities between organisms. We have in our body, sequences that come from all walks of life that mirrors our ancestry. Genetic residues or ancestral relics exist from our ancestors. What about comparative anatomy? We could look at the fins of a dolphin and it’s analogous to a human hand (virtually identical except with a different cover). You could see the succession where animals went from water to land. We have a common evolutionary pattern. We have similarities which provides evidence for biogenesis.
We have basically two types of cells: Prokaryotes and Eukaryotes. All the mitochondria in your body came from your mother because when the sperm fuses with the egg, the only thing that enters the egg is the DNA and everything is left out. All the organelles come from the mother.
Endosymbiotic evolution: Mitochondria and chloroplasts came from bacteria. They have their own DNA. Mitochondria has 70S ribosomes that are identical to bacteria. Mitochondria also have their own DNA. They used to be independent at one time. Chloroplasts used to be independent photosynthetic bacteria.