4.2 The diversity of edible species
You will now familiarise yourself with the Dinner Plate Diversity tree and how it can be used to study dietary diversity.
Click ‘View interactive version’ if you do not currently have the interactive open. You should open the link in a new browser window or tab.
In the menu on the right-hand side of the interface, foods and species are available to select from drop-down lists. They are listed here by their common name, and when a selection is made (by clicking on the checkbox next to the item in question), that species is highlighted and its scientific name is given on the tree diagram. The species names are necessarily small, to fit them all in, but there are zoom in (‘+’) and zoom out (‘−’) controls that will allow you to see things in more or less detail, as required.
A text box also appears when a checkbox is ticked. This box provides more taxonomic information, including the relevant family and kingdom. These details may be useful as you explore the diversity of what people eat. At times only a genus name is given, often because many species in this genus are eaten with little distinction between them by consumers. Anchovies are an example of this, as while there are six commonly eaten species (all in the Engraulis genus), the species information is often not identified in ingredients lists, so this selection only appears as Engraulis.
You will need to input primary ingredients or the species from which they are derived when exploring the foods in a diet. For example, milk comes from cows, honey from bees, and coconut water from coconuts, so you would need to select these species from the lists in order to include their associated produce in any dietary diversity analysis. Similarly, ingredients listed in a recipe may still need to be considered as their components. For example, pomegranate molasses includes pomegranate, sugar and lemon (juice). You may have to do a little research online to help unpack the components of a given ingredient.
Given the many species on the list, there is a search function in the right-hand menu that can to help you find food efficiently. If your edible species doesn’t show up there, you can search for them manually using the various drop-down lists below the search box. There are several common foods in the ‘miscellaneous category’ at the bottom, such as coffee and sugar, so don’t forget to check that one too if they form part of the diet you are analysing.
There is also an ‘Export’ button that allows you to access details of any checkboxes that you have got ticked at that particular moment, in order to copy them into a spreadsheet program. You may find this feature useful if you want to compare the taxonomy of several species at once.
Activity 4 Exploring the diversity of edible species
There are now five tasks to complete to help you explore the tree and learn a bit more about the biodiversity of different diets. Note your answers down in the boxes available after each. There is a ‘Clear all’ button in the right-hand menu of the interactive, which you can use to clear all your previous selections between questions. You can write as much or as little as you like, but word-count guidance is provided to help with time management.
Compare the dietary diversity of someone who likes bananas, guava and watermelon with someone who likes apples, strawberries and plums. Note down the family each species is from to help you describe what you find. (75 words)
Apples, strawberries and plums are all in the Rosaceae family, meaning they are quite closely related. In contrast, bananas, guavas and watermelon are in the Musaceae, Myrtaceae and Cucurbitaceae families, respectively. From a phylogenetic perspective, this is therefore a much more diverse set of fruits. In line with this higher diversity, you may have also noted that they are much more spread out on the tree diagram than are apples, strawberries and plums.
What other edible species are in the Cucurbitaceae family? (Hover your mouse over the watermelon and surrounding species in order to view the text box that contains further information. You can also zoom in to see the surrounding species more easily.) (50 words)
The commonly eaten species in the Cucurbitaceae family include cucumber, zucchini, watermelon, winter melon, and butternut squash. Interestingly, this family includes things which are commonly referred to as both fruits and vegetables even though scientifically they are all fruits.
Look at the number of species in the ‘Poultry, meat and dairy’ category in comparison to the ‘Fish’ and ‘Shellfish’ categories. (You don’t need to count them exactly, just consider their relative numbers.) Select those that you think are domestic animals from these lists, note which family they are in, and describe where the domestic animals fit into the larger list of all animals on the tree. (100 words)
Domestic animals include cows, sheep, pigs, goat, chicken, duck, geese and possibly rabbit. Although fish and other aquatic food are farmed there are no domestic species of fish and shellfish.
The diversity of fish and shellfish that people can eat is much greater than the number of species of mammals and birds. The domestic animals we eat are in five families: Bovidae (cows, goats, sheep), Suidae (pigs), Leporidae (rabbits), Anatidae (ducks, geese) and Phasianidae (chicken). The mammals are clustered together and the birds are in a different cluster, reflecting their relatedness.
Select the following foods: broccoli, brussel sprouts, cauliflower, kohlrabi and kale. What do you notice about their diversity? (50 words)
All of these foods are the same species. They have been selectively bred over many years to produce different strains in which different plant parts have sought-after characteristics. In broccoli and cauliflower you eat the flower buds, brussel sprouts are lateral leaf buds, cabbage is the terminal bud, kohlrabi is the stem and kale is the leaves.
Salt and black pepper are common condiments. How do they fit into this tree? (50 words)
Black pepper is the only species in the Piperaceae family on the tree. Salt is not on the tree as it is not an edible species – it is a chemical compound and the salt you eat comes from inorganic, non-living sources.
You should now have a better understanding of species being closely or distantly related, and how to describe this using terms such as ‘family’, ‘genus’ and ‘kingdom’. Activity 4 may also have given you some surprises about the species you eat (such as broccoli), which made you think more deeply about the food on your plate. This activity was about a range of edible species, which you may or may not eat, but next you will look at the species from the dietary data that you have gathered yourself.