Natural selection

• Natural selection can be influenced by the movement of emigrant species that cause gene flow
• Natural selection can be influenced by mates being chosen for specific traits that will turn out more dominant as the favored species will more likely reproduce
• Natural selection can be influenced by population shrinks with surviving species having better influence on gene pools of the ecosystem
• Natural selection is the concept of species better adapted to environments having increased chances of their gene being passed onto the next generation
• Lamarckism suggests that structures used frequently and consistently will strengthen, develop, enlarge, and be passed onto next generations. This means that physical changes like scars onto an organism are heritable
• Darwinism suggests that heritable variations influence an individual's survival and reproduction rates and is passed onto offspring. Over time, the beneficial ones will persist in a population and the rest will die out.
• Darwinism suggests Natural selection
• Lamarckism was disproven due to the fact that the germline, reproductive cells in charge of passing traits to new generations are distinct from the somatic cells that influence an organisms physical characteristics that are acquired from their lifestyle
• A paradigm shift is a fundamental change in the understanding of a phenomena
• The shift from Lamarckism to Darwinism was a paradigm shift
• Theories like natural selection that are born from observations use inductive reasoning
• Inductive reasoning is the process of using specific observations to form a general conclusion
• Natural selection adheres to the correspondence theory as it accurately describes the way the world is
• Natural selection adheres to the coherence theory as it fits within a larger, consistent set of knowledge
• Natural selection adheres to the pragmatic theory as it has practical consequences that work and are useful in real world scenarios
• Heritable traits are encoded in DNA and don't change across generations unless due to natural selection and sexual reproduction mixing single gametes of DNA to create a new variation.
• Acquired characteristics are developed over a person's lifetime and do not involve changes to DNA base sequences and hence does not affect the traits passed onto the next generation
• Genetic variation can result from mutation which is the original source of it with new alleles produced due to changes in DNA and causing variation
• Gene flow is another source of genetic variation as it involves the movement of genes between different groups of organisms
• Meiosis is another source of genetic variation as it involves the crossing over and independent assortment during the forming of egg and sperm cells that create it
• Sexual reproduction is a source of variation due to the random fertilization of the egg and sperm of different parents
• While variation is random, the probability of a variation being passed onto new generations is dependent of its impacts on the survival and reproduction rates of its population
• Variations that promote survival and reproduction will be selected fro and will increase in frequency in a population
• Variations that reduce survival and reproduction will be selected against and will decrease in frequency in a population
• Beneficial mutations include a change in DNA that results in a protein that improves functioning and increases the organism's chances of surviving and reproducing, hence will be selected for
• Harmful mutations include a change in DNA that results in a protein that does not function normally or at all, decreasing the organism's chances of survival and reproduction, hence it is selected against
• Neutral mutations include changes to DNA that have no observable effect on an organism and can be a result of a silent mutation that does not affect the structure of function of the protein it codes for or might change traits that do not affect survival and reproduction rates of the organisms
• Example of harmful mutations are sickle cells that are still prevalent because of their heterozygous trait of preventing malaria
• Example of beneficial mutations are the mutation of a cytosine into a thymine that allows for lactose tolerance later into life when usually adults become lactose intolerance
• There is increasing trend of more offspring being produced than can be supported by habitat wherein natural selection ensures the survival of the fittest offsprings as there are enough offspring to ensure that enough are fit to continue the species.
• Overproduction of offspring also allow for increased genetic diversity within species that allow for better adaptations to a changing ecosystem
• Natural populations will exhibit logistic growth in which rapid growth occurs at first when the population is small and resources are plentiful then it slows as resources limit expansion. This is the carrying capacity of the ecosystem, where the number of births are equal to the number of deaths.
• Direct competition involves where one individual directly affects the others' ability to get resources (ex. Male elks using aggression to fight for dominance and attract female mates)
• Indirect competition involves individuals indirectly competition for the same resources (ex. eating fish that then can't be consumed by others further down the stream)
• Selection pressures are variables in an environment that cause certain phenotypes of an organism to increase its chances to survive and reproduce
• Selection pressures can be negative (in decreasing its presence) or positive (increase its frequency)
• Selection pressures are the driving force of evolutions by natural selection because it is a way of determining the best species at surviving and reproducing
• Biotic selection pressures include predation, competition, disease, availability of food, and finding and attracting mates
• Abiotic selection pressures include temperature, water availability, pollutants, wind, light availability, O2 CO2 concentrations and natural disasters
• Abiotic selection pressures are density independent meaning they are the same no matter the population density