Walking Fish Reveal how our ancestors evolved Into Land

 

  Walking Fish Reveal how our ancestors evolved Into Land - Approximately 400 million years ago fish colonies began to explore the land and evolved into tetrapods - today amphibians, reptiles, birds, and mammals. However, there are two things that the scientific mystery to this day, that is how the ancient fish use their fins in the body and the terrestrial environment and evolutionary process what happened.

 

The journal Nature published the results of a study conducted by researchers at McGill University who studied the fish Polypterus to learn how to fish the first time be able to walk on land. Polypterus fish is a fish from Africa are able to breathe a breath of air, walk on land, and is similar to the ancient fish that have evolved into tetrapods. The researchers put Polypterus young fish to the mainland for more than a year that aim to reveal how fish move inland and anatomical changes what happened.

Said Emily Standen, a former McGill post-doctoral student who led the project, at the University of Ottawa that "environmental stress conditions can show anatomical changes and variations of behavior, this is a form of developmental plasticity". Further said Emily "We want to use this mechanism to see anatomy and new behavior and we can use this fish to see if they fit with what we know from the fossil record."

Remarkable anatomical changes in fish

 

Fish show anatomical and behavioral changes are significant. Fish terrestrialized more effective by placing their fins closer to their bodies, lifted their heads higher. "Anatomically, they turn into a skeleton chest becomes more elongated with a strong attachment to their chests, perhaps to increase support for walking and reduced contact with the skull potentially allowing movement of the head / neck bigger," said Trina Du, Ph. D McGill student.

"Because a lot of anatomical changes are reflected in the fossil record, we can hypothesize that changes in behavior that we see today reflect what might happen when the fish fossils first walk with their fins on land," says Hans Larsson, Canada Research Chair in evolution macro at McGill and Associate Professor at the Redpath Museum.

Experiment "Polypterus The terrestrialized" is a unique experiment and provide new ideas of how fish use their fins in fossil terrestrial environment and evolutionary process what happened.

Larsson added: "This is the first example we know that demonstrate plasticity can facilitate the development of large-scale evolutionary transitions, by first accessing new anatomy and behavior that will be genetically improved by natural selection."

The study was conducted by Emily Standen, University of Ottawa, and Hans Larsson, Trina Du at McGill University.

This research was supported by the Canada Research Chairs Program, the Natural Sciences and Engineering Research Council of Canada (NSERC) and Tomlinson Post-doctoral fellowship. 


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Why Fish Affected by the disease ?

Why fish Affected by the disease ? - This question arises when we find different occurrences of the condition of the fish healthy. Diseases in fish farming is a scary thing for farmers. Due to the hard work starting from land preparation, stocking up with the necessary maintenance and other costs will change with the loss if the fish are exposed to the disease. Fish disease occurs when fish (host), live in aquatic environments that are less suitable for fish life, but supports the pathogen to multiply or proliferate. This will lead to changes in the pathophysiology of the organs of the body of the fish.

 

The incidence of disease in the fish pond is the result of interactions between fish mismatched, environmental conditions and disease organisms. Mismatched interactions have caused stress to the fish, so that the self-defense mechanism that has become weak and vulnerable to disease eventually. If the host body's defense is weak and pathogens found in many host body, but still appropriate and supportive environment to improve the disease resistance of the host body would not appear because pathogens can not proliferate.

 

Humans play an important role in efforts to prevent the occurrence of disease in fish in pond aquaculture, in particular by maintaining the harmony of the interaction between the three aforementioned components. Generally plague that attacks fish in the pond are caused by human error in managing the pool environment. For example, bacteria of the type of Enterobacter sp., Aeromonas hydrophila and Pseudomonas sp. the cultivation of freshwater in the 1980s which has caused the death of dozens of tonnes of freshwater fish in West Java (Rukyani, et al. 1996). Recent cases of disease is disease Koi Herves Virus (KHV), which is a viral disease in koi and goldfish in Java in 2002 due to the negligence of the farmers maintain the cleanliness of the pool, so that the harmony of the three components that cause disease to be disturbed. KHV infection that started happening in Java has spread to Bali, Sumatra and South Kalimantan. Even in 2005, cases of KHV has struck carp in fish farming activities in the lake Toba, which is then followed by the prohibition to send a goldfish to the island of Sumatra which was a fish quarantine area.

In normal conditions, the three factors namely the fish, the environment and pathogens will be able to maintain balance. Cultivated fish that we will utilize food derived from food-grade, so that the fish can grow well, reproduce in order to continue the descent, unable to defend themselves from changes in the surrounding environment well. The occurrence of disease in fish is due to the imbalance between the three factors above. The bodies pathogens will usually cause interference resulting in a change in environmental conditions resulting in decreased immune system of fish (fish become stressed). In fish cultivated the disease can strike at all sizes ranging from seed, fish consumption is up to the parent. A disease that usually attacks the fish seed is usually due to parasitic infection, while at larger sizes usually are fungi that attack, wound ulcers, and lumps.


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