User:Faisha S/sandbox

Another study investigated the possible effects of gut microbiota in the expensive-Tissue Hypothesis among vertebrates. Researchers have investigated various symbiotic gut bacteria as well as other microorganisms that have coevolved in the human or other animals digestive tract. These microbiotas have evolved to form mutually and beneficial relationships with their host, they are important for immune function, nutrition and human physiology and any disruption in the gut can lead to gastrointestinal dysfunction like obesity for example. Several studies have also shown that the diversity and the composition of the gut microbiota vary topographically and temporarily. This is because specific bacteria have been linked to the host’s food intake as well as the use of nutrition and energy metabolism. Any changes or modifications of the microbial landscape in the gut can lead to several complex and dynamic interactions throughout life. In other words, the choice of the host is strongly associated with the diversification and complexity of the microbial, for instance, the study illustrates that diet high in fat increases the level of Bacteroidete and decreases the level of Firmicute in children’s gut, the study also theorized that diet quality is also related do gut size. The study also found out that gut size has also seen coevolution in brain size, partly because both the brain size and gut are one of the most energetically costly organ in vertebrateses body. Base on the Expensive-Tissue Hypothesis higher energy expenditure of vertebrates with a larger brain has to balance out by following a similar decrease in other energetic consuming organisms, in this case, the gut’s size. There has also been an evidence that shows that vertebrates with larger brains have evolved to balance out the energetic expenditure required by trading-off with the gut size. For example, researches have found a negative correlation between brain size and gut size in gruppies (Poecilia reticulata) as well as Omei wood frog (Rana omeimontis) .Gut microbiota responds to diet quality in a way that influences the metabolism of the host. For instance, improving energy yield in the host or altering the metabolic pathways is one of the main processes that drive the trade-off between brain size and gut size. This process is also correlated with the ETH hypothesizes because the brain size increases when energy input is at a high level due to consumptions of extra diet and the overall increase constant energy input. However, after several investigations, the study could not find strong evidence to support that brain size is negatively correlated to the gut microbiota in the vertebrates. A similar study done by Tsuboi et al., shows clear evidence that the brain size is correlated with the gut size by controlling the effects of shared ancestral and ecological confounding variables. The study found that the evolution of a larger brain is closely related to the increase in reproductive investment into egg size and parental size. The result of the experiment concluded that thenegetic cost of encephalization maybe involved in the evolution of brain size in both endothermicic and ectothermic vertebrates. For example, the study founhomeothermic vertebrae such as elephant nose fish,Gnathonemus Gnathonemus petersii has a large brain that is related to a smaller intestine ansns stomach size. Which suggested that energy constraints on brain size evolution are found in at least highlencephalizeded tropical speciesAdditionalal, the study found that the evolution of brain size is associated with an increase in egg size and an extended period of parental care. This shows that the presence of the energetic constrains of encephalization are not can also be applied to homepthermic vertebrates .Even though the study provided a distinct evidence to prove that brain size and gut size are negatively cooeralted with one another, however their weren't a strong evidence to prove that. For instance most of the study done on the live bearing and egg bearing species within Chondrichthyans, cannot be generalized across all homothermic and ectothermic vetebrateseses.