Evolution

In order for Biomes and Ecosystems to fluctuate successfully with life, they need Biodiversity. Biodiversity is the variety of life, which measures on the number of different species within a given environment. If an Ecosystem or a Biome have a diverse range of species populating the given area, it proves that it is a Diverse Environment.

Species

In order for an ecosystem to be diverse, different species need to be established. Species are identified through populations of organisms with similar characteristics, and are unable to reproduce viable offspring with other organisms.

Because of this, you can have very different species co-existing within the same habitat. They're unable to breed with each other, but are able to survive in the same environment.

Life isn't as simple however, and the world can through pressuring factors that can limit and affect the rate of a species population and their survival. Because of these limiting factors, organisms begin to adapt.

Adaptation

Adaptation is where an organism changes from the rest of their population, and this can be through Anatomical, Physiological, and Behavioural changes in an attempts to benefit and increase the rate of survival for the overall species.

An Anatomical Adaptation is where the organism physically changes that differentiates from the normality of their species (see figure 3).

For example, Panthera Pardus Orientalis (Amur Leopard) has dark spots in order to provide camouflage within the dense Temperate forests that it resides in. A couple millions of years ago, Leopards and Lions diverged from their common ancestor, and despite both species deriving from the same family tree, each species looks very different in regards to anatomical structure and fur pattern (San Diego Zoo Global, 2015).

A Physiological Adaptation is where the organism changes in regards to their abilities and/or functions.

For example, a Birch Tree, a common deciduous tree found within Temperate Forests, drops its leaves within the winter.

Figure 3. A Diagram showing the evolutionary changes of large cats in relation to their environment (Fritz, 2015).

This ability is used to avoid damage from the snow, and reduces snow build up on it's canopies (Gakuin, 2015).

A Behavioural Adaptation is where the behaviours and actions of an organism differentiates from the species normal behaviour.

For example, Panthera Pardus Orientalis catches their prey and then hides the catch when they've finished. They store their food away for later to eat at a later date, and to avoid other predators from stealing their meal, such as other competing leopards and Amur Tigers (Oregon Zoo, 2015).

Speciation

These differentiating adaptations are important for biodiversity, because as the species begin to change in different aspects, they begin to split from their species catergorisation, and after many generations of alternation, they can end up to a point where they are so different that they can no longer breed with each other, and seperate into their own species (National Geographic, 2015). This process is called Speciation.

Evolution

When Speciation occurs, organisms are evolving into their own unique beings. Evolution is when the gene pool of a population changes.

Despite common belief, evolution does not occur within individuals, mainly because all offspring are born with different traits within their gene pool. However, when a trait becomes a common normality found within a populous, to the point where the entire population is beginning to share this trait, then it becomes Evolution (Global Change, 2002).

Remember; Species do not evolve, Populations do (Abyss Uoregon, 2009)!

Evolution can occur through five mechanisms; Population Decrease, Gene Flow, Mutation, Mating, and Natural Selection.

Population Decrease is exactly as the name implies; where a population is reduced drastically in numbers from either internal or external sources (Merriam Webster, 2015). Whilst this can help save other species who may have been restricted or hunted by another species that is decreasing in population size, this can also have an effect on the remaining organisms in the ecosystem by inbalancing the food web and altering possible influencing factors. This can be caused by limiting factors, natural factors and human factors (New Hampshire Public Television, 2015).

For example, in the wild, there is a limited number of shelter, food, water and space. This affects the success rate of a species living within the conditions they find themselves in. If a species of animal found themselves in an environment that lacked a sufficient supply of prey that they could sustain their species on, there would be an overall decrease in the population until there was a lesser population that could survive. Sciurus Vulgaris (Red Squirrels) are in direct competition with Sciurus Carolinensis (Grey Squirrels) in Europe over food and territory, and because Sciurus Carolinensis is more efficient at finding and storing food, the population of Sciurus Vulgaris has dramatically decreased (see figure 4 - Red Squirrels Survival Trust, 2015).

Figure 4. A Magazine print acknowledging the decrease in Sciurus Vulgaris population due to the succession of Sciurus Carolinensis (British Demographic Party, 2012).

Humans could also be a factor resulting in population decrease of a species. Panthera Pardus Orientalis, for example, struggles through both the loss of habitat and poaching, which has drastically reduced its population numbers to only 30-35 left in the wild, making the species critically endangered (Bleiman et al, 2011).

Gene Flow is where organisms immigrate (enter) or emmegrate (leave) an ecosystem (see figure 5 - Rockman, 2015). This makes the gene pool larger and more diverse, allowing new family trees to enter the system of reproduction in the given ecosystem, creating alleles and thereby increasing the variation within the genetic pool. Despite this, it can also have a negative impact; organisms can leave the ecosystem, therefore reducing the gene pool into an even less dense pocket, increasing the chances of inbreeding and risking mutations in the offspring (O'Neil, 2012). Gene Flow can be affected by the location of the species' population, the species itself, and the individuals of the species. Some species of animals are known to migrate, however it is dependant on the species that regards the tendency to create gene flow. Travelling with their population is different from a few of the population moving into a new one. Depending on the organism's nature and behaviour would be an altering factor in this. Sometimes it is impossible for the population to move into a new environment, or there are no other populations of the same species that they can interbreed with (Mallet, 2001).

Mutation is where natural changes occur through breeding, and an offspring may be born with a defying difference that could either benefit or hinder its survival rate. This process is random, and commonly do not attribute towards the survival of the individual (Allen et al, 2015). When a mutation is detremental to an organism's health, it is called a genetic disorder, meaning the organism isn't as able to survive as its normal counterpart, and its survival chances are lowered (Carlin, 2011). However, if a mutation is beneficial and can aid towards the survival of the organism, it is called an adaptation. This is where the mutation can make survival for the organism easier than its average species, and is better adapted to survive within its circumstances (King et al, 2007). It is needed within evolution to have mutations, otherwise organisms would not be able to create new sources of genes and alleles, preventing genetic variation, which is needed to keep the genetic pool diverse enough to disperse into different species entirely (Gray, 2013). On the other hand, mutations are rarely beneficial to species, and can result in eventual loss of specific type genes of that organism, resulting in the offspring losing what could have potentially benefitted their survival (Wright, 1932). Whilst some mutations are small (eg blue eyes in humans), some can drastically affect the chances of survival (eg having an extra limb) (Highfield, 2008). Mutation is caused by small genetic disruptions and/or errors through the combining of DNA (in reproducing). This can also be influenced by strong sources of radiation in the environment that could reduced the chances of a successful offspring (Bleiman et al, 2011).

Mating is through who mates with who within the given gene pool. In order for genetics to be passed through generations, it is required to be recieved through the DNA given from the parents of an organism. However, mating isn't as simple as chance; animals are required to choose a suitable mate (or mates) that they deem suitable for passing offspring with, and we can see this through the behaviour of each organisms (Jones, 2009). Sexual selection usually occurs through an organism's perspective of 'special circumstances' that leads to mating; most commonly influenced through combat between males and the overall choice of females (Shuster, 2009). This process can be beneficial as it not only provides the future generations of the species, but the female is able to choose a male who is most likely to provide beneficial care towards their young; this can be direct (usually in monogamous relationships such as the swan, where the male helps raise and protect the young) or indirect (where the male has little to no interaction with their young, but is successful in territorial and breeding standards, able to supply the offspring with a safe territory to be raised in and ward off other males that may kill young that are not their own) (Raven, 2012). However, mating doesn't always fall into the catergory of choosing the best in show. Sometimes numbers are limited of a species, and they may be left to reproduce with others only because they are the only available options (regardless of the physical state of the parents) or may be unable to breed at all. The limitations in breeding can cause inbreeding, which leads to more negative mutations and unsuccessful offspring, or could become so serious that extinction could become a threat to the population. Lack of possible mates can also alter the behaviour of the population, influencing emmigration in search for others to reproduce with (Johns, 2002).

For example, female Pavo Cristatus (peahens) only submit to male Pavo Cristatus (peacocks) whose feathers are the brightest and most appealing on display, as well as most other female birds who favour towards large/colourful plumaged males (Jones, 2009).

Natural Selection is where the population is affected by external pressures (that can be both abiotic and biotic), to the point where they adapt in order to survive. Through the genetic diversity of the population, certain traits that an individual may have could benefit their survival rate within their environment under the external pressures, and gives them a more liekly chance of surviving and reproducing, passing their traits down to the next generation (Andrews, 2010). Natural Selection is caused by the chances of an organism's survival rate in regards to its physical, physiological, and behavioural traits. If an organism is better suited to its environment, it has better chances of surviving to the age of sexual maturity where it can then pass on it's successful traits down to its offspring (Pianka, 1990). Whilst this is effective at moving evolution forward and adapting species further for their own survival, it sacrifices a lot of the species through natural selection. The organisms with weaker traits or traits not as significant as others will find it difficult to survive and can deplete completely. Not only this, but if a species were isolated and were not abundant in useful traits, the organisms that breed could pass down unwanted or uneccesary traits that could effectively hinder or crash the species population. Natural selection is one of the many causes that lead to inbreeding defects within small populations, and can eventually lead to a species extinction (Pianka, 2000).

For example, Figure 7 shows the same species of beetle that can be found in two variations of colour; because one is more vibrant in its traits, it is more susceptible to predators and is more likely to get eaten than the paler coloured beetle. The paler beetle has a higher succession rate than the vibrantly coloured, and thus its trait becomes hereditary within it's offspring. Natural selection decides that the paler coloured beetle is better camouflaged for it's environment, and thus is more successful in surviving (The University of California Museum of Paleontology, 2015).

Figure 5. An illustration showing the process of gene flow (Rockman et al, 2015).

For example, some plants can distribute their pollen into new ecosystems to fertilise other plants by being carried through the wind. Being able to be carried miles away from their original environment, the pollen can then fertilise other species of plants and create alleles on a large scale (Boundless, 2015).

For example, Biston Betularia (Peppered Moth - see figure 6) is an insect known to be very light in colour to blend in with the light bark of trees to hide from predation, but in the 19th century, pollution occurred through factory fumes, staining the trees and their leaves black. Black Biston Betularia are present, however they were very few in numbers as they were a common mutation within the species. Thanks to the stained trees, black Biston Betularia were able to hide from predators more efficiently than their white counterparts, and were more likely to successfully breed and carry their unique chromosone through to their offspring. Despite their temporary succession, when the trees were finally cleaned, black Biston Betularia numbers reduced rapidly, their adaptation becoming a disorder and making them easier to spot for birds, now estimated to only having 1% of the population to be black by 2019 (Bates, 2011).

Figure 6. The two known variations of the Peppered Moth caused from a succesful mutation during the INdustrial Revolution (Robinson, 2011).

Figure 7. An example of Natural Selection through coloured beetles (TUCMAP, 2015).