BIOL3045 Lecture Notes - Lecture 20: Migratory Locust, Desert Locust
3 Jul 2018
School
Department
Course
Professor
Animal Ecological Physiology BIOL3045 460381099
Lecture 20: Nutritional ecology.
Amounts based nutritional geometry LAB: Target selection and rules of compromise.
Determining intake targets
• When given a variety of diets, see which food priority drives foraging.
• Step 1: Induce imbalance. Step 2: Free choice. Cockroaches given either a high protein food, high
carb food or intermediate food for 48 hours and then given access to all 3 foods for 120 hours
and when plotted on a nutrient space all 3 groups were found to converge to the 1 point
therefore showing they have an intake target and balance their nutrition to get to this point;
Locusts were fed 2 of a concentrated high protein or high carb diet or a dilute high protein or
high carb diet. Found they balance nutrients by both selecting which foods they eat as well as
the amount they eat (when food is dilute they eat more) which contradicts foraging theory
because they don't eat to maximize energy intake or they would eat more of the concentrated
foods. Also, they will compensate food for energy needed in flight by selecting specific foods,
and amounts of food that replenish what is lost in flight.
Determining rules of compromise
• When given an imbalanced nutrient combination, individuals will display one rule of
compromise. So they will show a deficit of one and an excess of another.
• Migratory locust produced a curve = specialist (Excess < Deficit). Desert locust produce a line =
generalist (Excess = Deficit as they are able to ingest larger nutrient excesses). There was also
found to be genetic basis for ROC because a hybrid produced an intermediate spectrum
• By taking a species that has two developmental forms. Example: Desert locus has a gregarious
generalist stage (reared in high density) and a specialist stage (reared in low density). If this is
true, we would expect them to change regulatory patterns. When a generalist feeder is put into
a specialist environment they feed like specialists and therefore they are able to
developmentally adapt to the regulatory pattern appropriate to their nutritional ecology.
Document Summary
Determining intake targets: when given a variety of diets, see which food priority drives foraging, step 1: induce imbalance. Locusts were fed 2 of a concentrated high protein or high carb diet or a dilute high protein or high carb diet. Also, they will compensate food for energy needed in flight by selecting specific foods, and amounts of food that replenish what is lost in flight. Determining rules of compromise: when given an imbalanced nutrient combination, individuals will display one rule of compromise. So they will show a deficit of one and an excess of another: migratory locust produced a curve = specialist (excess < deficit). Desert locust produce a line = generalist (excess = deficit as they are able to ingest larger nutrient excesses). There was also found to be genetic basis for roc because a hybrid produced an intermediate spectrum: by taking a species that has two developmental forms.
