Determining Factors Affecting the Natural Selection of Woodlice - Lab Report Example

Woodlice are crustaceans with tough, segmented, lengthy exoskeletons usually with fourteen joined limbs Freeman (Freeman 45). Its scientific classification is shown in the table below.

They have a shell-like exoskeleton that progressively shed as they grow. The shedding occurs in two stages where the back half sheds first followed by the front part later usually two to three days later as opposed to the way the molting process occurs in other anthropods where the cuticle is shed in a single process. Metabolic rate is temperature dependent in woodlice which is in contrast to mammals and birds where their rate of respiration depends directly on the external environmental temperatures (Jordan 100).

Woodlice are claimed to have an unpleasant taste like that of urine despite being a crustacean which is different from the taste of other crustaceans like lobsters or crabs. Woodlice breathe through their plepodal lungs and live in the terrestrial environment usually damp or dark places to reduce the rapid rate at which they lose water through their cuticle and excretion (Sutton, Stephen, Paul, and David 67). Although woodlice are preyed by a wide range of insectivores it’s the spiders that prey on them exclusively. The length and dorsal plate in all woodlice were measured using a microscope and recorded. The speed of three woodlice was obtained by taking two rulers to measure the distance and then assorted utensils for simulating predation and mimicking a predator were simulated and the timer was set from the time all the three woodlice started moving until they all reach the end of the two rulers and then recorded in seconds.

Woodlice were placed in large specimen dishes and the predator for this experiment which was a spider was simulated RESULTS The woodlice traits were varying as like where the highest standard deviation error was obtained from the speed and the lowest standard deviation error was obtained from the length while the standard deviation error was zero as illustrated in the table(1) below Trait Dorsal plate number Speed (seconds/10 cm) Length (cm) Color (values using soil color chart) Mean 7 21.20833333 0.

991666667 5.083333333 Standard Deviation 0 +10.29131828 +0.21450989 +1.248187091 Standard Deviation Error 0 +2.100706547 +0.043786648 +0.254785123 Table (1) showing traits, mean, standard deviation and standard deviation error of woodlice In the frequency distribution below blue represents the total number of woodlice while the red represents the number of woodlice that survived after the predator was unleashed. From the graph the number of surviving populations is higher than the total population between the speeds of 1-20 and the same is exhibited between the speeds of 21-40 and between the speeds of 61-80 but between the speeds of 41-60, no woodlice survived.

Frequency distribution of woodlice characterized by speed DISCUSSION From the table and the frequency distribution above it is clear that there is a relationship between the population of woodlice that survived the experiment and their speed.