Natural Selection Biology

INTRODUCTION:

Natural selection is a process of evolution this occurs due to both biotic. Natural selection is the survival and reproduction of individuals with different phenotypes. In some cases natural selection can be directly observed, Data from the Earth Watch Institute show birds beaks from the Galapagos Islands being naturally selected for throughout different environmental changes such as, after droughts occur and the islands are dry the bird population has stronger beaks which allows them to eat tougher seeds .

Human activity has also lead to changes to the environment that have caused populations to evolve through natural selection. An example of human activity effecting evolution is; around the year 1850 in the United Kingdom,

grey moths were naturally selected for due to the good air quality resulting in low pollution allowing pale lichen to grow, covering the trees where the grey moths live, camouflaging them into the moss and reducing sight predators catching and killing them. During the industrial revolution large quantities of coal were burned, polluting the air wrapping the light moss covered trees with black soot. This changed the environment for the dark moths to be selected for as they camouflaged and less visible to sight predators, they had increased survivability which also meant increase in reproduction and pass on the favourable dark moth gene . This investigation is
Peppered Moths used to represent natural selection in a specific habitat. Coloured toothpicks will be used to represent organisms, and will be placed in one of three different habitats. Predation will occur along with reproduction. The results will be recorded and used to develop an understanding of the effect a colour of an organism has on predation in relation to it environment.

AIM: 
To investigate the colour effect on natural selection by a sight predator.

HYPOTHESIS: 
The stick insects complementarily coloured to the habitat will camouflage and be less likely seen by the sight predator, therefore will be naturally selected for survival.

VARIABLES:

CONTROLLED VARIABLES:

MATERIALS:

METHOD:
Collect materials required for investigation.
Select 3 habitats (Grass, Gravel and Bark/ Leaf).
Measure a 2 m2 (1.4 m X 1.4 m) square using string.
One member of the group must randomly scatter individual stick insects within the square whilst the remaining members look away as they will portray sight predators.
The sight predators enter the habitat, and quickly locate and capture the stick insects. However, each stick insect found must be selected one at a time and put into a plastic container. A stopwatch may be used to time how long it takes for 40 of the 60 stick insects to be retrieved.
Once 40 stick insects have been retrieved, record how many stick insects of each colour were captured in this first round of predation.
Each surviving stick insect or each of the remaining 20 stick insects now reproduce a - sexually and produce 2 more stick insects of the same colour as itself. Randomly scatter these new 40 insects into the habitat.
Repeat steps 2-4 until 3 rounds of predation have been completed.
Repeat steps 1 through 9 to the two remaining habitats. Record results.

OBSERVATIONS AND RESULTS:
HABITAT 1 : GRASS
TABLE

GRAPH

HABITAT 2 : BARK/ LEAF LITTER
TABLE

GRAPH

HABITAT 3: GRAVEL SURFACE
TABLE
GRAPH

DISCUSSION:
As seen in the tables and graphs above, all three habitats selected the brown stick insects for survival, followed in order by green, beige, pink, yellow and then finally red. In the grass environment the brown stick insects finished with 48 total surviving predation. Whereas red, yellow, pink and beige all finished with 0 stick insects total surviving these results were. The results stayed relatively constant throughout all three trials.
The results found in the bark/leaf litter were brown stick insects total survival 59 and followed by green total survival of 3. Once again the following coloured stick insects total survival rate was 0,similar to the results of the gravel surface brown coloured stick insects were clearly the species that has the highest chance of survival. The brown stick insects were the only species left in the third trial of the gravel habitat. This means that the whole total population consisted of completely brown coloured stick insects.
When analysing the results, not only is the colour of the stick insects crucial because it is the defining factor that determines how each of the coloured species will survive differently in each environment, but also the colour of the environment must be taken into consideration.

As stated in my hypothesis stick insects complementarily coloured to the habitat will camouflage, however, this hypothesis was untrue as the green environment did not select the green stick insects for survival. Instead the brown stick insects were selected for as they were very hard to see, and therefore survived. All of the other insect species were contrasting in colour against the green when they were scattered throughout the grass habitat, making them easy to see and therefore easy to pick up. The gravel habitat also selected for the brown stick insects, the habitat already had a lot of brown coloured sticks which looked identical to the stick insects. This made it very hard to see the brown species and allowed them to survive at an increased rate. The red coloured insects has a final population of zero, because of the deep red colour, which made them easy to identify against the orange pebbles. The bark/leafy habitat was made up of dark black dirt, green foliage and fallen yellow and brown decaying leaves. When brown toothpicks made up the majority of the population by the third trial, it was clear that the brown was the hardest to see when placed in the

environment.

This information we have collected gives us a greater understanding of the process of natural selection.

Natural selection is the name given to the development of species where they adapt their environment increasing the chances of survival and therefore allowing them to further produce offspring. As a part of evolution animals have the ability to alter their colour to better suit them to their environment. The stick insects placed in the environment were contrasting colours of the environments except for the brown stick insects who camouflaged in all habitats. An example of this is the Peppered Moth. The Peppered Moth are normally a grey colour with black speckles, but a genetic mutation can cause them to have black wings. The white moths found it easy to camouflage with the trees before the industrial revolution compared to the black moths, and therefore the black moths suffered from predation. During the industrial revolution, the air became polluted meaning that the darker coloured moths were harder to see. The black moths therefore had the favourable genes, allowing them to reproduce and increase in population. Therefore, this is a prime example of Natural

Selection. 


IMAGES

ERRORS:
The area of the
The colours of the stick insects, it was hard to distinguish between the red and brown stick insects. Mistakes could have been made by collecting a red stick and recording it as red whilst it is actually a brown stick insect.

SYSTEMATIC ERRORS: - may have occurred
The units on the ruler used to measure the area of each environment may 
not have been true, therefore the environment may not have been truly 
1.4m x 1.4m.
As there was little technology used, there was little possibility of a systematic 
error occurring. 

IMPROVEMENTS:
Increasing the number of environments would have allowed for a larger number of main colours to be investigated and then a further understanding of Natural Selection would have be developed.
The number of trials performed at each location would have increased the accuracy of the results, as it would have allowed for a better average.
There was only one ‘predator’ used to pick up the toothpicks in each environment, and therefore if there was different ‘predators’ used during a larger number of trials the results would allow for more evidence to be found.
The size of the square used to scatter the toothpicks was 1.4m x 1.4m. A larger area may have allowed for a more random pick up of toothpicks, much like the situation would occur in real life.
There were 6 colours used in the investigation. There are many different colours and shades that animals can be found in, therefore, more coloured toothpicks would allow for more accurate data.