Fitness biology is the study of how physical activity impacts our bodies and how this response can be improved, providing essential knowledge in terms of prevention of chronic diseases as well as overall improvement to health and wellbeing.
Biological fitness measures the capacity of an organism to survive and reproduce within its environment, with generations-based changes either increasing or diminishing it.
Environment
There are various biotic (living) and abiotic (non-living) factors that impact organism survival, including temperature, water availability, predators, food sources and environmental influences.
Fitness is an integral concept in biology as it measures an organism’s ability to survive, reproduce and produce offspring. Also referred to as Darwinian fitness, fitness measures an individual’s capacity for transmitting genetic information from one generation to the next.
Environment can have an immense influence on the evolution of traits that will ultimately increase an organism’s fitness. For instance, animals with traits making it harder for predators to spot may increase their chances of surviving more open environments, ultimately increasing reproductive success and success rates.
Genetics
Fitness biology examines how genetic variations influence an organism’s traits, health, and disease. It’s an intricate science that explores how certain combinations of genes may lead to specific phenotypes (phenotypic expressions).
Not only can genotypes and phenotypes affect fitness of an organism; there are other factors such as environmental conditions, adaptive mechanisms, and natural selection that influence fitness as well.
Reproductive success is one of the primary factors determining fitness; therefore, traits which increase reproductive success may make an organism better adapted to its environment.
Natural selection is the process by which those organisms best adapted to their environment become more numerous in a population, through three major forms of selection – directional selection, stabilizing selection and diversifying selection.
Phenotypes
Phenotypes are the outward physical characteristics that a living thing displays, including appearance and behavior. Phenotypes depend on both genetic information that an organism carries (known as genotype), as well as environmental influences which might impact it.
Phenotypes can either be dominant or recessive, as well as heterozygous individuals who possess two alleles combining to express the trait.
Example: in terms of eye color, a heterozygous individual with two recessive alleles would exhibit blue eyes; this condition is known as homozygous recessive genotype.
Phenotypes play an essential role in fitness biology, yet their role in evolution remains poorly understood. Many evolutionary theories focus on the effect of environmental conditions on phenotypes; however, this represents only one facet of the relationship between an organism’s phenotype and fitness.
Reproduction
Reproduction is a vital process that ensures the survival of an organism or species; without it, they could perish altogether or go extinct.
All living organisms, from microbes to trees, exist due to reproduction. Reproduction occurs through various methods that can generally be divided into two groups: asexual reproduction and sexual reproduction.
Asexual reproduction refers to any process by which organisms produce offspring without fertilization and distribution across their environment. This type of reproduction occurs among bacteria, plants, animals, and even some humans.
Sexual reproduction requires two members of the same species sharing genetic material to create offspring that are genetically identical to both parents; offspring created through mitosis result in daughter cells that are genetically identical to their parent cell and, as a result, appear exactly alike to each other.
