There are a couple of configuration options available when configuring a Search API index that we haven't looked at yet: adding additional fields, and using boost values to increase the relevance of a keyword when found in a specific field.
Solr allows you to index any number of additional fields, so we'll add a species and genus field to our index. This is one of the reasons using Search API to interface with Solr is so great. Through it's use of the Entity API, the Search API module has a deep understanding of all the content types on your site and the fields that are attached to them, without you having to write any code, or do anything other than configure things in the UI.
One of the benefits of creating your own search index is that you know your data better than anyone, and you know what people are hoping to find in your content. Solr allows you to configure a boosting value that can be used to increase the relevancy of keywords found depending on where in the data it's located. For example, when someone searches for a keyword we can probably assume that if the keyword is in the page title that the keyword is worth more relevancy points than if the keyword is found in the page body. With boosting we can affect the relevancy ranking of results and help our users more quickly find what they are looking for.
By the end of this tutorial you should be able to add additional fields to your Solr index so their content is available for searching, as well as assign a relevancy boosting value when keywords are found in specific fields.