Size Decline Of Exploited Fish Populations : Microevolution Or Phenotypic Plasticity?

If feeding efficiency and reproduction have a direct correlation, and a population started with equal proportions of individuals with each of three feeding types, metal spoon, metal knife, and plastic fork, the frequency of the population with metal spoons as their feeding structure will increase in the next generation. While the frequency of metal knifes and plastic forks will decrease. Furthermore, since the organisms with the metal spoon feeding structure have a higher fitness level, this population will evolve by natural selection to a point where the metal spoon phenotype will be in abundant. While the organisms with metal knifes and plastic forks phenotypes will decrease in frequency due to the lack of reproduction. Eventually, if this population persist overtime, most of the organisms, if not all, will have the metal spoon phenotype, while very few, if not any, will have the metal knife or the plastic fork phenotype.

According to Darwin and his theory on evolution, organisms are presented with nature’s challenge of environmental change. Those that possess the characteristics of adapting to such challenges are successful in leaving their genes behind and ensuring that their lineage will continue. It is natural selection, where nature can perform tiny to mass sporadic experiments on its organisms, and the results can be interesting from extinction to significant changes within a species.

One reason may be that because smaller organisms have a tougher time surviving than larger ones, smaller ones produce more offspring to guarantee the survival of their genes through generations.

From the data we can conclude that different traits or parameters can effect a population in many different ways. It can decrease or increase a population depending on the trait. After a hurricane hits Lake Malawi the cichlid fish male population must adapt to the new factors that have been put upon them. Mutation within the population supports the fact that it can cause dominant and recessive allele frequency to decrease. Migration causes the allele frequency to lower as well due to movement of the population after the hurricane. The cichlid male fish with a higher fitness are more suitable for their environment, but when their fitness is lowered, their allele frequency decreases. This

Microevolution: evolutionary change within a species or small group of organisms, especially over a short period. Basically, microevolution studies small changes in alleles that occur within a population. Over time, these small

From the San Francisco Bay to streams and rivers of Oregon, salmon populations have been steadily decreasing over the past two decades but more rapidly within recent years. In general, fish populations in the Pacific Northwest region have always fluctuated, but the overall trend continues on a downward slope to extinction. While natural phenomena such as flooding and predators of the food chain do affect salmon populations, human activity poses the greatest threat by far. The four main reasons of salmon plummeting are as followed: Harvest, Hatcheries, Hydropower, and Habitat. It’s clear that water ecosystems and management of human activity threaten salmon as a whole. Whether it’s a bay, river or stream- whatever body of water that contains salmon should be subject to ethics that guide our actions as a part of achieving a better overall environment.

The purpose of the research was to formulate a question and develop a hypothesis based on the variations observed between two populations of threespine stickleback, in order to gain a better understanding of natural selection

In the article, “Rapid Evolution Saved This Fish From Pollution, Study Says” written by Joanna Klein she investigates the evolution of Atlantic Killifish in New Jersey. The people of New Jersey are restricted from eating any fish, especially the killifish, from the Lower Passaic River and Newark Bay. This is because of the obsessive dumping of chemical waste and toxins into the waterways. This waste is affecting the local ecosystems located in that area, but drawing attention to the Atlantic Killifish. In the 1990’s researchers discovered that the Killifish were “tolerant of the toxic waters.” In areas along the Atlantic coastline researchers found out that the Killifish located in different highly toxic areas had already rapidly adapted genetically

The delta smelt is an estuarine fish that is endemic to the San Francisco Bay-Delta region of California. This species was listed as endangered under the California Endangered Species Act in 2010 after extended extremely low abundance indices. The historical range of the delta smelt extended from San Pablo Bay to Sacramento along the Sacramento River and Mossdale along the San Joaquin River. Delta smelt became extinct in the southern region of their native range in the 1970s and experienced a steep population decline in the 1980s. The greatest factor in the decline of the delta smelt is the anthropological impact on their native ecosystem. The introduction of invasive species and the alteration of their habitat from variable tidal systems to leveed channels have significantly decreased suitable habitats for certain life stages of the delta smelt. Also, the highly controversial exportation of water from the Delta has had a major impact on delta smelt populations. Large water pumps in the southern region of the Delta are both detrimental to delta smelt habitat and have the direct effect of killing individuals through entrainment in the pumps. According to several previous studies, the exportation of water is one of the key factors when it comes to the genetic diversity, as well as the distribution and abundance, of the delta

Black sea bass is an important recreational and commercial species along the Atlantic coast of the U.S. The market for black sea bass is for human consumption and is primarily sold fresh or frozen. In May of this year, NOAA scientists declared the southern stock of black sea bass successfully rebuilt. The catch limit for this popular fish will more than double this fall. The rebuilding plan was required by the Magnuson-Stevens Fishery Conservation and Management Act, which requires that overfishing end immediately, that overfished stocks be rebuilt, and that stocks be subject to annual catch limits. The fish are also larger on average and are showing up in places where they haven’t

A. Rus hoelze et al, studied the impact of intense hunting of Northern Elephant Seals in the late 19th century, whose genetic variation reduced due to this bottleneck. This reduced their population size to just about 20. They found that although it has since rebounded to over 30K now but compared to their southern counterparts i.e., Southern Elephant Seals they have much less genetic variation. The Southern Elephant Seals didn’t went through this bottleneck event. It is clear that the genes of Northern Elephant Seals still carrying the marks of this bottleneck.

“If no such variations exist, the population rapidly goes extinct because it cannot adapt to a changing environment” (O’Neil, 1998-2013). Scientists call this reproductive success. “Within a specific environment context, one genotype will be better than another genotype in survival or reproduction for certain reasons having to do with the way its particular features relate to the environment or relate to other organisms within the population” (Futuyma, 2000-2014). The theory of evolution is explicable through various kinds of scientific research.

Recently updated on October 4, 2017, a LSU Boyd Professor discusses how the size of an economically important fish, known as Menhaden, has shrunk in size. Size as in length, weight, population, or physically overall, has shifted in the past years and how it has affected the ocean life.

When that happens over many generations a species’ gene pool changes to only include the traits that are a best fit for ensuring survival of that species, and a new species may evolve. In the case of the Galapagos finches Darwin studied, biologists have since found that one of the differences was their beak size, which were adapted to the specific seeds available to the finches as food on the different islands. This would support this principle as only the birds able to eat the local seeds would be able to survive to reproduce, thus over many generations, new finches with a variety of different beak sizes would “evolve”. The

Keywords from the Aquatic Science & Fisheries Thesaurus: Environmental factors, Genetic diversity, Fjords, Marine fish, Marine Biodiversity,