General Information
The sardines or pilchards come from the herring family of Clupeidae. These fish normally tend to grow 15 cm tall and are oily. Between the 1980s and the 2000s the sardines were being over fished but with the closing of many fisheries due to laws the sardine population has increased exponentially in the past couple of years. They have been eaten over many centuries and are considered very healthy rich in vitamin - B12.
The Sardine Run
Adaptation And Behaviour
The video above is of a behavioural gene in sardines which leads to something called Swarming. Swarming is used to get away from predators by sardines. When the sardines come together they may scare a predator away by making it think the prey is to big or it may be just that when swarming goes on the predator gets confused as to which fish it will eat first and it is more likely to survive within a group rather then by itself as it could easily be spotted alone by a predator and fall prey to it. The swarming pattern is inherited in sardines therefore it naturally makes a group and comes together when a predator is near by. Swarming is not only used by sardines to get away from predators but a variety of other fish use it as well and surprisingly land mammals such as wild buffalo use it as well.
Evolution (4-points of Natural Selection)
Variation
The variation between the sardines would be whether the sardines behavioural patterns led it into a group or would it stay by itself to get away from predators.
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Struggle
The struggle was that more and more predators were eating the sardines the way that they could get away from a predator or higher their chances of survival and pass on their genetic information was they would have to come together into a swarming pattern which would reduce their chances of getting eaten.
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Environmental Selection
Within the environment the sardines with the behavioural gene that led it to come together in a swarming pattern were the ones that had better chances of survival and passing on their genetic information. While the sardines that did not have the behavioural gene that led it into group would have less chances of survival and would have a less of a chance of passing on its genetic information therefore it was unfit compared to the sardines with the behavioural gene of swarming and therefore the sardine with the behavioural gene was selected.
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Reproduction And Inheritance
When the sardines with the behavioural gene that led it get into groupings were environmentally selected more and more sardines with the gene survived and passed on the gene to their offspring's and this gene became prominent in many generations that came after it until most sardines had the gene.
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Note - The Sardine comes within the Animal Kingdom
Behavioural Adaptation
Swarming is a type of behavioural adaptation it is not a part of the sardines internal or external features it is controlled by a gene which is passed down from parent to offspring.