Sugar Metabolism in Hummingbirds and Nectar Bats

Hummingbirds and nectar bats coevolved with the plants they visit to feed on floral nectars rich in sugars. The extremely high metabolic costs imposed by small size and hovering flight in combination with reliance upon sugars as their main source of dietary calories resulted in convergent evolution...

Full description

Saved in:
Bibliographic Details
Published in:Nutrients 2017-07, Vol.9 (7), p.743
Main Authors: Suarez, Raul K, Welch, Kenneth C
Format: Article
Language:English
Subjects:
Animals
Bats
Birds - metabolism
Calories
Carbohydrate Metabolism
Chiroptera
Chiroptera - metabolism
coevolution
convergent evolution
Diet - veterinary
dietary carbohydrate
Energy Metabolism
enzyme activity
Exercise
Flight
flight muscles
Flight, Animal
Fructose
Fructose - metabolism
Glossophaginae
glucose
Glucose - metabolism
honey
hummingbirds
hydrolysis
Intestinal Absorption
intestines
Lipid Metabolism
Metabolism
Models, Biological
Muscle, Skeletal - physiology
Muscles
Nectar
Oxidation
Oxidation-Reduction
Plant Nectar - metabolism
Review
Structure-function relationships
Sucrose
sucrose alpha-glucosidase
Sugar
Trochilidae
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Hummingbirds and nectar bats coevolved with the plants they visit to feed on floral nectars rich in sugars. The extremely high metabolic costs imposed by small size and hovering flight in combination with reliance upon sugars as their main source of dietary calories resulted in convergent evolution of a suite of structural and functional traits. These allow high rates of aerobic energy metabolism in the flight muscles, fueled almost entirely by the oxidation of dietary sugars, during flight. High intestinal sucrase activities enable high rates of sucrose hydrolysis. Intestinal absorption of glucose and fructose occurs mainly through a paracellular pathway. In the fasted state, energy metabolism during flight relies on the oxidation of fat synthesized from previously-ingested sugar. During repeated bouts of hover-feeding, the enhanced digestive capacities, in combination with high capacities for sugar transport and oxidation in the flight muscles, allow the operation of the "sugar oxidation cascade", the pathway by which dietary sugars are directly oxidized by flight muscles during exercise. It is suggested that the potentially harmful effects of nectar diets are prevented by locomotory exercise, just as in human hunter-gatherers who consume large quantities of honey.
ISSN:2072-6643
2072-6643
DOI:10.3390/nu9070743