The difference in reproductive strategies among aquatic species of various size Essay

In many aquatic species size dependent breeding and alimentary success are the norm with the larger animal having triumph over smaller individuals of the same species. Smaller individuals, which would have an overall smaller reproductive success, would most likely adapt alternative reproductive strategies in order to succeed in reproducing and allocating resources. Alternative strategies are expected to be hereditary since males who employ them have greater reproductive success and yield the same fitness as those who do not rely on them. This is the case in mating behavior of the species Macrobrachium rosenbergii where reproduction differentiates in behavior related to the size of the males.
Upon closer examination, researchers have concluded the prevalence of three different morphotypes in Macrobrachium rosenbergii each correspondent to specific traits and sizes. First, males with blue claws are the largest ones in the population expressing dominant, territorial behaviors. Secondly, researchers found the smaller orange claw males expressing sub-dominant, non-territorial behaviors. Lastly, Small males which exhibit little to no dominance and are non-territorial. It is important to note that individuals of the population can undergo changes from one to the other in the order of small to orange claw to blue claws but not in the reverse order. Transformations in both behavioral and physical factors are mostly due to the disappearance of larger individuals in the species. This being said, researchers have found all three morphotypes to coexist in equal ratios which remain constant through several generations. During this study, researchers compare the reproductive success of each of the morphotypes by observing their individual alternative strategies.
The study showed that there is a big difference in reproductive strategies between blue claw males and small males since big males are more attractive to females and spend more time protecting females from others of its species while smaller males are faster and tend to sneak to a female protected by a blue claw male and mate with her. On the other hand, orange clawed males used a strategy which is not as useful as the other morphologies since it is believed that they are only an intermediary developmental stage between small males and blue claw males. Equal overall fitness benefits can be explained by taking into account the benefits of blue claw males having higher fertilization rates than smaller males but at a higher cost of energy expenditure which decreases its ability to adapt to the changing environment and decreases average life span and thus reproductive possibilities. Meanwhile, the small males can adapt to the changing environment at a quicker pace because of lower energy expenditures but have a lower possibility of mating with females.
The study confirmed that there were no genetically determined bases for the appearance of alternative strategies in the species M. rosenbergii but that these strategies are dependent on the amount of fitness costs and benefits associated with the size within the population of the species and environmental factors that can cause alterations. Overall, both strategies are proved to be effective for reproduction success.