BIOL 520 INTRODUCTION

 P henotypic Plasticity Option 2  Phenotypic plasticity is the responses by individuals to shifting conditions, such as changes in environmental change. Phenotypic plasticity, the environment-dependent expression of phenotypes by genotypes, can substantially alter the phenotypic distribution of populations over time without a genetic change. Plasticity is evolutionarily favored when the environment is heterogeneous in time or space, selection favors different phenotypes in different environments, no one phenotype has the greatest fitness across all environments, and reliable cues allow organisms to respond effectively There are costs associated with acquiring environmental information, producing different phenotypes, and maintaining the physiological and developmental capacity for facultative responses. however, can substantially constraint the evolution of phenotypic plasticity.      Phenotypic plasticity, the expression of different phenotypes from the same ...

     Fitness    Evolutionary geneticists use fitness to predict changes in the genetic composition of populations through time .   Fitness is defined in evolution by how well a species can reproduce and survive in its environment. Fitness is the quantitative representation of natural and sexual selection within evolutionary biology. Fitness is measured by an organism's ability to survive and reproduce, which determines the size of its genetic contribution to the next generation. The central concept of natural selection is the evolutionary fitness of an organism.      There are several ways to measure fitness; for example, “absolute fitness” measures the ratio of a given genotype before and after selection while “relative fitness” measures differential reproductive success — that is, the proportion of the next generation’s gene pool that is descended from a particular organism (or genotype) compared with competing organisms (or genotyp...

  Mutation The four postulates presented by Darwin are as follows: 1) Individuals within species are variable; 2) Some of these variations are passed on to offspring; 3) In every generation, more offspring are produced than can survive; and 4) The survival and reproduction of individuals are not random; the individuals who survive and go on to reproduce the most are those with the most favorable variation, and they are naturally selected. The mutation is fundamental to evolution because it generates the genetic variation on which selection can act. Darwin's postulates are allied with a variation. There are three main reasons that cause Mutation. Mutations are caused by environmental factors known as mutagens. Types of mutagens include radiation, chemicals, and infectious agents. Mutations are caused by environmental factors known as mutagens. Mutations may be spontaneous in nature. Mutations may be spontaneous in nature. I think the mutation rate can evolve. Under adverse envir...

  Diabetes is not a new disease it was first documented in 1550BC in Egypt. Historians believe back then diabetes was used to consider a rare disease. They are closely related to the obesity epidemic in those countries. In fact, type 2 diabetes is said to be a lifestyle disease. A person dies every six seconds from the disease. Diabetes is a chronic disease that affects millions of people worldwide. The worldwide prevalence of diabetes was 2.8% in 2000, and it is expected to increase to 4.4% by 2030. The total number of persons with diabetes worldwide is estimated to increase from 171 million in 2000 to 366 million in 2030. Diabetes is a collection of multiple metabolic diseases, in which high levels of blood glucose are present over an extended period of time. Most persons with diabetes remain undiagnosed early in the disease process. In most cases, blood glucose levels in persons with diabetes increase with age, leading to heart disease, stroke, chronic kidney failure, foot ulcer...

  Speciation is the process by which reproductive isolation evolves between populations. The evolution of reproductive isolation is typically a gradual process that occurs along a gradient, starting from a single variable population, continuing to differentiated populations that are still connected by gene flow, and finally ending in distinct and reproductively isolated species . There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric, peripatric, parapatric, and sympatric . In  allopatric speciation , groups from an ancestral population evolve into separate species due to a period of geographical separation. In sympatric speciation, groups from the same ancestral population evolve into separate species without any geographical separation. In parapatric speciation, two subpopulations of a species evolve reproducti...

  Usually, females tend to be choosier, evaluating morphological and behavioral traits from potential mates to determine which will maximize their fitness. Males tend to compete with one another to gain the female's attention. In the broad-nosed pipefish, males become ‘pregnant’ and care for their embryos until birth. In this scenario, the male is choosier about potential female mates. The female lays her eggs into the male's brood pouch, where they are fertilized. The male incubates the eggs for approximately two weeks before they hatch. He then releases a cloud of tiny, fully formed pipefish from his pouch into the water. Males of pipefishes, seahorses, and seadragons (family Syngnathidae) care for developing embryos on their bodies from mating through to birth. In genera with brood pouches, such as  Syngnathus , the care provided has similarities with mammalian pregnancy, so brooding males are said to be ‘pregnant. Many species exhibit polyandry, a breeding system in whic...