Evolution of Herbivory in a Carnivorous Clade of Minnows (Teleostei: Cyprinidae): Effects on Gut Size and Digestive Physiology

Abstract

We constructed a phylogeny for 10 minnow species (family Cyprinidae) previously revealed to be members of sister genera with different dietary affinities and used the phylogeny to examine whether the evolution of digestive tract size and physiology is correlated with the evolution of diet in these fishes. We studied a total of 11 taxa: four herbivorous species in the genus Campostoma and six largely carnivorous species in the genus Nocomis, including two populations of Nocomis leptocephalus, the carnivorous Chattahoochee River drainage population and the herbivorous Altamaha River drainage population. Thus, we were able to compare digestive tract size and physiology among sister genera (Campostoma and Nocomis) and among sister taxa (N. leptocephalus Chattahoochee and N. leptocephalus Altamaha) in dietary and phylogenetic contexts. The herbivorous taxa had longer digestive tracts and higher activity of the carbohydrases amylase and laminarinase in their guts, whereas the carnivorous species had higher chitinase activity. Phylogenetic independent-contrast analysis suggested that the evolution of amylase and chitinase activities was correlated with the evolution of diet in these species, whereas trypsin and lipase activities showed no pattern associated with diet or phylogenetic history. Concentrations of short-chain fatty acids were low in all taxa, indicating that these fishes rely largely on endogenous digestive mechanisms to subsist on their respective diets. Subtle differences in tooth shape were observed between species in the two genera. Overall, our results suggest that dietary specialization can be observed on the level of anatomy and physiology of the digestive tracts of fishes but that such differences are most appropriately viewed in comparisons of closely related species with different diets.

Evaluation of biofilm of Aeromonas hydrophila for oral vaccination of Channa striatus

“…The stomach environment in carnivore fish is quite different from that of herbivore and omnivore characterized by high acidity and intense activity by digestive enzymes [12,13,41]. And, the performance of oral vaccine heavily depends on the stomach environment.…”

“…Till today, we evaluated the biofilm oral vaccine in herbivore and omnivore fish. Therefore, information is required on performance of biofilm vaccine in a carnivore fish where the stomach environment is quite different from that of herbivorous carps and omnivore catfish [12,13,41]. Futhermore, antibody response was evaluated by agglutination titre.…”

Insects as Food for Insectivores

“…In reality, the fiber in whole insects likely represents a variety of different compounds, including chitin, sclerotized proteins, and other substances that are bound to chitin (Finke, 2007). Chitinase activity has been reported in certain species of frogs, lizards, tortoises, fish, and bats, suggesting that certain insectivores might be able to digest chitin (Donoghue, 2006;Fujimoto et al, 2002;German et al, 2010;Whitaker et al, 2004).…”

Induced and constitutive responses of digestive enzymes to plant toxins in an herbivorous mammal

“…To better study the role of evolutionary experience in determining responses to PSCs, studies must be conducted to survey clades where herbivory has evolved several times independently, thus allowing for phylogenetic or taxonomic correction [e.g. liolaemid lizards (Espinoza et al, 2004), cyprinid minnows (German et al, 2010) or a wider survey of cricetid rodents (Samuels, 2009)]. Additionally, this question can be investigated at higher trophic levels.…”