Questions: During the Jurassic Period, several different mammalian lineages independently evolved an herbivorous lifestyle for obtaining energy. This has resulted in different digestive patterns in herbivorous animals, some that depend on gut microbiota to digest plant material and some that do not.

The answer is the first one: different digestive patterns in herbivorous animals, some that depend on gut microbiota to digest plant material and some that do not.

Explanation for each option:

1. Different digestive patterns in herbivorous animals, some that depend on gut microbiota to digest plant material and some that do not.

   • This option is correct because during the evolution of herbivorous mammals, different lineages developed various digestive strategies. Some rely heavily on gut microbiota to break down cellulose and other plant materials, while others have developed different mechanisms that may not rely as much on microbial fermentation.

2. Different digestive patterns in herbivorous animals that all depend on gut microbiota to digest plant material.

   • This option is incorrect because not all herbivorous mammals rely on gut microbiota for digestion. While many do, there are some that have evolved other methods to process plant material.

3. The evolution of foregut fermentation, as seen in ruminants, as the only digestive pattern that depends on fermentative gut microbiota.

   • This option is incorrect because foregut fermentation is not the only digestive pattern that relies on gut microbiota. Hindgut fermentation is another common strategy seen in animals like horses and rabbits.

4. Horizontal gene transfer of genes for glycoside hydrolases and polysaccharide lyases from bacteria to mammals.

   • This option is incorrect because while horizontal gene transfer is a known phenomenon, it is not the primary explanation for the evolution of herbivorous digestive strategies in mammals. The evolution of these strategies is more about the adaptation of existing mammalian physiology and the symbiotic relationship with gut microbiota.

In summary, the first option correctly captures the diversity of digestive strategies among herbivorous mammals, some of which rely on gut microbiota and some of which do not.