Radishes And Collard Lab Report
Survival and Leaf Growth of Radishes and Collards in Intraspecific and Interspecific Settings
Abstract
The purpose of the experiment was to observe how density and competition among individuals of the same species and of different species affects the growth of leaves and survival of collards and radishes. The experiment was carried out in the Greenhouse at the University of South Carolina, and utilized set up with six groups with four pots per group. The pots consisted of low density radishes, low density collards, high density radishes, high density collards, low density radishes and collards together (mixed-species pots), and high density radishes and collards together. After six weeks of growing, biometrics were taken, and specifically …show more content…
for this experiment, the weight of the leaves and the survival of the plants from seeds. We hypothesized that in the intraspecific competition setting, both the radishes and the collards in the low density pots would achieve higher leaf weights due to having less competition than the higher density setting. In the interspecific competition setting, we hypothesized that the radishes would experience higher leaf weights and greater success due to stem length being greater than collards. From the results, the intraspecific setting showed that the high density condition yielded the greatest leaf weight, rejecting our hypothesis. This is most likely due to human errors that occurred during the six week period of growth and development. In the interspecific setting, the radishes achieved greater survival, due to the interspecific competition setting having less intensity than that intraspecific setting. As for the leaf weight, the results displayed that there is not a significant difference in radishes and collards, which may have something to do with intraspecific competition within the interspecific setting (the plants also must compete with their own species in the interspecific pots).
Introduction
In the natural world, species interact with other individuals of the same species and with individuals of a different species. These interactions can be beneficial to the species or they can be harmful, especially when competition for resources is the interaction. If the competition for resources occurs within the same species, it is termed “intraspecific competition” (Fill, 2014). On the other hand, competition between different species is “interspecific competition” (Ricklefs, 2013). Intraspecific competition typically results in the most intense competition due to the fact that the individuals are identical in physiology and require the same resources. However, interspecific competition can be equally as harsh, especially in the event of extremely high population densities. As a result of competition, one species usually achieves higher fitness while the other species’ fitness decreases (Gustafsson, 1987). In terms of this experiment, the purpose was to observe how these interactions (intra- and interspecific competition) affect the fitness of individual radish and collards plants grown in a controlled environment. Radishes and collards are two examples of plant species that exhibit both interspecific and intraspecific competition. Understanding how the two species grow under conditions with and without the presence of “outsiders” will provide valuable information. For example, growing crops of these plants may be inhibited by the presence or absence of one another. If it is found that they grow better when competing with a different species, farming businesses can maximize their production of crops, which has become increasingly important in relation to the growing world population. In the experiment, we manipulated twenty-four pots with low and high densities of radishes and collards in an intraspecific and interspecific competition setting. The purpose for conducting this experiment is gain a better understanding of how organisms in the wild interact with each other and affect other individual’s growth and overall fitness. Due to having some pots with intraspecific competition and interspecific competition, two hypotheses were formulated. In the intraspecific setting, we hypothesized that both species, the radishes and collards, would achieve higher leaf weight in the low density pots. The low density results in less competition for resources, allowing for a higher per capita benefit for each individual (in this scenario, leaf weight). In the interspecific competition setting, we hypothesized that the radishes would experience greater leaf weights and success (number of surviving individuals) in the low and high density setting because of possessing a stem that is longer than collard stems. Due to the longer stem, the radishes would have access to more sunlight than the collards. Interactions between the radishes and collards displays how fitness is impacted by the presence of competitors, which, we as humans, can use to maximize the survival and growth of mass produced crops.
Materials and Methods The organisms used in the experiment were Raphinus sativa (radish) and Brassica oleracae (collards). The experiment was setup in the USC Greenhouse, and utilized twenty-four pots. Each pot was filled tightly with soil, then the seeds of the radishes and collards were dispersed evenly within each pot. In the low density intraspecific pots, we placed eight seeds of radishes or collards in the soil. In the high density intraspecific pots, we placed sixty-four seeds of radishes or collards in each pot. In the low density interspecific pots, we placed four seeds each of collards and radishes together. Lastly, in the high density interspecific pots, we placed thirty-two seeds each of radishes and collards together. For each of these pot settings, there were four replicates, making a total of twenty-four pots. After placing the seeds evenly throughout the surface of the soil, about one centimeter of soil was lightly applied to the top layer to cover the seeds. Next, the pots were labeled according the setting (interspecific/intraspecific) and whether they were of high or low density. Following labeling the pots, they were each placed together in the greenhouse for six weeks and taken care of by the lab instructor. After the six weeks expired, the groups gathered together at the greenhouse for collection of the data. The plants were removed from the soil by carefully pulling them at the base of the stem, being sure to not separate the stem from the roots. The total number of successes (surviving plants) was recorded for each pot after being pulled from the dirt. Dirt remaining on the roots was washed away, and the underground biomass of the roots was recorded for each individual of each species, in each setting. In all settings, the data for each individual was recorded except for the stem length, where an average of five stems from each setting was recorded to get an estimation of the true stem length. Aside from underground biomass, other data collected for each individual included total leaf weight, number of leaves, and stem weight. The collected data was then normalized, and for the hypotheses of this experiment, the normalized areas were the proportion of survivors (number of plants/number of seeds planted) and the average leaf weight (total leaf weight/total number of leaves). After normalizing the data, an ANOVA analysis was performed on the data using Microsoft Excel, for both species in order to see the relationship between mechanisms, survival, and leaf weight. The single factor analysis was used for intraspecific pots to compare the leaf weights between the two species at high and low densities. Similarly, the two factor analysis was used for the interspecific setting to calculate the effects of the species on one another at high and low densities. Based on the results of the ANOVA analyses, conclusions could be drawn about if the density and competition with the same or different species affected the survival and growth of leaves. The ANOVA generated a P-value (less than 0.05 rejects the null hypotheses) which would then confirm whether or not there was a significant difference in the interspecific and intraspecific settings, as well as the high and low density settings, for leaf weight and survival.
Results
The average weights of the leaves for radishes and collards was used for comparison in the intraspecific setting. Table 1 shows the single factor ANOVA for the radishes in low and high density, which produced a P-value of 0.483193. The experiment’s α-level was set to 0.05, showing that high density collards achieved greater leaf weight. Graph 1 displays the average leaf weight in a more visual way.
ANOVA: Single factor analysis for radish leaf weight in low and high densities
ANOVA
Source of Variation
SS
df
MS
F
P-value
F crit
Between Groups
0.189244
1
0.189244
0.504085
0.483193
4.170877
Within Groups
11.2626
30
0.37542
Total
11.45185
31
Table 1: Single Factor ANOVA analysis of the average leaf weight (grams) for radishes in a low and high density intraspecific setting.
Graph 1: The average leaf weight of the radishes can be seen to be much higher in the high density setting, not supporting the hypothesis.
The collard leaf weight was also recorded (grams), and another single factor ANOVA analysis was performed to provide more information. The P-value in this analysis was 0.903093, again much higher than the α-level. Table 2 summarizes the analysis of the collard leaf weight in high and low densities. Graph 2 also displays visually, the difference in the average leaf weight of the collards. Although the average leaf weight is ever so slightly higher in the low density setting, it is not significantly higher (0.04462 grams in low density as compared to 0.04346 grams in high density).
ANOVA Single factor analysis for collard leaf weight in low and high densities
ANOVA
Source of Variation
SS
df
MS
F
P-value
F crit
Between Groups
1.1E-05
1
1.1E-05
0.015077
0.903093
4.170877
Within Groups
0.021868
30 …show more content…
0.000729
Total
0.021879
31
Table 2: ANOVA Single factor for collards at low and high densities (leaf weight) yielded a P-value of 0.903093.
Graph 2: The average leaf weight for the low density setting is slightly higher than high density setting in collards, but not significantly different.
In the interspecific competition settings, a two factor ANOVA analysis was performed (Table 3). For the leaf weights, three different P-values were generated. The P-value for the species section was 0.344904, indicating there is not a significant difference between the species in the interspecific setting. For the density section, 0.680005 was the obtained P-value which indicates that in the interspecific competition setting, there is no difference based on high and low density—the outcome would be the same in either situation. For the interaction section, the P-value given by the ANOVA was 0.826446, which essentially means there is no relationship between high and low density pots versus the type of species. In Graph 3, the average leaf weight for collards and radishes in the high and low density interspecific setting is visualized.
ANOVA: Two-Factor with replication for radish and collard leaf weight at low and high densities
Source of Variation
SS
df
MS
F
P-value
F crit
Species
0.001393
1
0.001393
0.90635
0.344904
4.001191
Density
0.000264
1
0.000264
0.171789
0.680005
4.001191
Interaction
7.46E-05
1
7.46E-05
0.048497
0.826446
4.001191
Within
0.09224
60
0.001537
Total
0.093972
63
Table 3: Two Factor ANOVA analysis generated P-values for each of density, interaction, and species for interspecific competition versus leaf weight. All P-values proved to be insignificant in light of the hypothesis, with α-level of 0.05.
Graph 3: the graph displays that there is not a significant difference in low and high densities of the mixed species pots, further failing to reject the null hypothesis.
For the survival of the single-species (intraspecific) setting, a single factor ANOVA analysis was performed again. For the radishes, Table 4 displays the results: with a P-value of 2.08 x 10-11, it is clear that the low density radish plants in the intraspecific competition survived enormously better than the high density radishes. Graph 4 displays the extremely noticeable difference in the low density versus high density intraspecific survival of the radishes.
ANOVA: Single Factor analysis for radish survival in the Low/High Density Intraspecific setting
Source of Variation
SS
df
MS
F
P-value
F crit
Between Groups
2.11087
1
2.11087
106.9293
2.08E-11
4.170877
Within Groups
0.592224
30
0.019741
Total
2.703094
31
Table 4: single factor ANOVA analysis of radishes in the intraspecific setting yielded a P-value of 2.08 x 10-11, which is extremely small in comparison to the α-level of 0.05.
Graph 4: the survival of the radishes in the low density setting can be seen defeating the high density setting by almost as much as 3x the number of survivors (0.8359375 as compared to 0.3222656).
For collards in the intraspecific setting, another single factor ANOVA analysis was performed to compare the number of survivors in the low and high density setting. Table 5 displays the results that were produced as a result: a very small P-value at 0.000284 indicates that the survival of collards in the low density single-species setting was much greater than the high density setting. Graph 5 also visually displays how well the low density intraspecific setting of collards fared as compared to the high density setting.
Anova: Single Factor analysis for collard survival in low/high density intraspecific setting
Source of Variation
SS
df
MS
F
P-value
F crit
Between Groups
0.293091
1
0.293091
16.86885
0.000284
4.170877
Within Groups
0.52124
30
0.017375
Total
0.814331
31
Table 5: the single factor ANOVA for the collards in the intraspecific setting generated a P-value of 0.000284, significantly smaller than the α-level.
Graph 5: the survival of the collards in the low density setting can be seen at about 3x greater success than the high density setting for intraspecific competition.
Lastly, another two factor ANOVA analysis was performed in terms of the success (survival) of the plants in the interspecific setting. Table 6 displays the species P-value generated by the ANOVA was 0.021921, indicating there is a significant difference in the survival of radishes and collards in the interspecific setting. The density P-value, 1, is extremely large and shows there is no difference whether or not the plants are in a high density or low density area when in mixed-species pots. Finally, the interaction P-value was also higher than the α-level of 0.05, at 0.679457, again indication there is no relationship between the low and high densities versus the plants species. Graph 6 displays the survival of the mixed-species setting at both the low and high density settings.
ANOVA: Two-Factor With Replication for radish and collard survival at low and high densities
Source of Variation
SS
df
MS
F
P-value
F crit
Species
0.282227
1
0.282227
5.536398
0.021921
4.001191
Density
0
1
0
0
1
4.001191
Interaction
0.008789
1
0.008789
0.172414
0.679457
4.001191
Within
3.058594
60
0.050977
Total
3.349609
63
Table 6: a two factor ANOVA analysis was performed for the survival of the plants, and indicated that the P-value for the species section was the only significant difference (0.021921), meaning that there was a difference in the survival of radishes versus collards. However, the P-value for density and interaction proved to be insignificant.
Graph 6: the survival of the mixed-species pots at high and low densities is displayed, showing that at low densities the radishes survived better and at high densities, the collards had higher survival.
Discussion In the intraspecific setting, we must reject our hypothesis that both the low density collards and radishes would achieve greater leaf weight. Based on the ANOVA analysis, the generated P-values for the radishes and collards were 0.483193 and 0.90309, respectively. Both values were above the α-level of 0.05, so the hypothesis must be rejected. Although the low density setting did not yield a greater leaf weigh than the high density condition, the survival of the radishes and collards in the low density intraspecific setting was significantly higher. The P-values were 2.08 x 10-11 and 0.000284 for the radishes and collards, respectively. These generated values are extremely small in comparison to the α-level of 0.05, indicating that the survival was much greater for both species in the low density intraspecific setting. In the interspecific setting, part of the hypothesis is rejected. For the leaf weight, we predicted it would be higher in the lower density mixed-species setting, however the generated P-values proved otherwise. For species, density, and interaction, they respectively were 0.344904, 0.680005, and 0.826446, all of which are much higher than the α-level. However, for the survival of the radishes versus the collards, the hypothesis was not rejected. In the mixed-species setting at both low and high density settings, the radishes had better success at surviving, as indicated by the ANOVA analysis with a P-value of 0.021921. The density P-value (1.000) did not prove to be significant, and neither did the interaction P-value (0.679457). Nonetheless, it is confirmed that the radishes do experience greater survival in the interspecific competition as compared to the collards, regardless of high or low density. Also, it is important to note that the success of collards in the interspecific setting was approximately the same for low and high density, seemingly doing better than when in the intraspecific setting (e.g. high density intraspecific collard survival was 0.105 while the high density interspecific collard rose to 0.273). From the results, it appears that the average leaf weight of the radishes and the collards shows an increase in the interspecific setting. Based on this, it is plausible to think that the two species should be grown together for agricultural purposes—higher leaf weight means the plant is thriving more. The rationale for this is due to intraspecific competition being more intense than interspecific competition, as stated before. When radishes or collards are competing within their species, they are all thriving for the same exact resources, making the competition more intense (Ricklefs, 2013). However, when grown interspecifically, the two species do not require the exact same resources, therefore the competition for resources is not so intense (Jones, 2014). From this, the intraspecific competition is obviously more intense than interspecific competition, which is what allowed for the two species to thrive together in the same pot and achieve a higher survival and leaf weight in the interspecific setting (Aguiar, 2001). Although the results came out in an unforeseen manner, they may be attributed to human error. It was mentioned to the groups that there was a malfunction in the schedule watering of the plants, due to the sprinkler system not working. This caused many plants to face drought-like conditions, inhibiting the growth and survival with almost entire certainty. Due to this, it cannot be stated with full confidence that these results are a fine depiction of what would really happen. However, due to this experiment being under drought-like conditions, a possible future experiment could be in flood-like conditions (inundation). If the radishes achieved higher leaf weight and survival in the mixed-species setting in drought-like conditions, perhaps the collards will benefit more in conditions with excessive water. Using the same experimental setup, replicate the procedure but add excessive amounts of water daily. Lastly, this experiment has provided valuable information on how the collard and radish species interact and affect the fitness of the competitors they are surrounded by. Based on this, we can proceed forwards with implementing the results into real practices of agriculture. Production of crops can be maximized and inversely, waste production will be minimized. In the growing world population, every last bit counts, therefore, knowing how these species grow best can have incredible effects on our hungry planet.
Acknowledgements
In this experiment, I thank all of my group partners. Tylar Lee, Owen Smith, Bradyn Holaus, and Joshua Haney. Each of them worked equally as hard as I did in completing the experiment and compiling the data. Also, I thank our lab instructor, Jen Fill, for providing every group with extra help and tips to complete the experiment properly.
References
1. Aguiar, M. R., Lauenroth, W. K., & Peters, D. P. (2001). Intensity of intra- and interspecific competition in coexisting shortgrass species. Journal of Ecology, 89 (1) Pp.40-47, 2001, Retrieved from http://search.proquest.com/docview/925275438?accountid=13965
2. Fill, J. (2014). Interspecific and Intraspecific Competition (Handout). Retrieved from https://blackboard.sc.edu 3. Gustafsson, L. (1987). Interspecific competition lowers fitness in collared flycatchers ficedula albicollis: :An experimental demonstration. Ecology, 68(2), 291-296. Retrieved from http://search.proquest.com/docview/14677246?accountid=13965
4. Jones, C. B. (2014). The Evolution of Mammalian Sociality in an Ecological Perspective, 13.
5. Microsoft. (2014). Microsoft Excel (Computer software). Redmond, Washington: Microsoft.
6. Ricklefs, R., & Relyea, R. (2013). Ecology: The Economy of Nature (7th ed.) (369). New York, NY: W. H. Freeman and Company
Abstract
The purpose of the experiment was to observe how density and competition among individuals of the same species and of different species affects the growth of leaves and survival of collards and radishes. The experiment was carried out in the Greenhouse at the University of South Carolina, and utilized set up with six groups with four pots per group. The pots consisted of low density radishes, low density collards, high density radishes, high density collards, low density radishes and collards together (mixed-species pots), and high density radishes and collards together. After six weeks of growing, biometrics were taken, and specifically …show more content…
for this experiment, the weight of the leaves and the survival of the plants from seeds. We hypothesized that in the intraspecific competition setting, both the radishes and the collards in the low density pots would achieve higher leaf weights due to having less competition than the higher density setting. In the interspecific competition setting, we hypothesized that the radishes would experience higher leaf weights and greater success due to stem length being greater than collards. From the results, the intraspecific setting showed that the high density condition yielded the greatest leaf weight, rejecting our hypothesis. This is most likely due to human errors that occurred during the six week period of growth and development. In the interspecific setting, the radishes achieved greater survival, due to the interspecific competition setting having less intensity than that intraspecific setting. As for the leaf weight, the results displayed that there is not a significant difference in radishes and collards, which may have something to do with intraspecific competition within the interspecific setting (the plants also must compete with their own species in the interspecific pots).
Introduction
In the natural world, species interact with other individuals of the same species and with individuals of a different species. These interactions can be beneficial to the species or they can be harmful, especially when competition for resources is the interaction. If the competition for resources occurs within the same species, it is termed “intraspecific competition” (Fill, 2014). On the other hand, competition between different species is “interspecific competition” (Ricklefs, 2013). Intraspecific competition typically results in the most intense competition due to the fact that the individuals are identical in physiology and require the same resources. However, interspecific competition can be equally as harsh, especially in the event of extremely high population densities. As a result of competition, one species usually achieves higher fitness while the other species’ fitness decreases (Gustafsson, 1987). In terms of this experiment, the purpose was to observe how these interactions (intra- and interspecific competition) affect the fitness of individual radish and collards plants grown in a controlled environment. Radishes and collards are two examples of plant species that exhibit both interspecific and intraspecific competition. Understanding how the two species grow under conditions with and without the presence of “outsiders” will provide valuable information. For example, growing crops of these plants may be inhibited by the presence or absence of one another. If it is found that they grow better when competing with a different species, farming businesses can maximize their production of crops, which has become increasingly important in relation to the growing world population. In the experiment, we manipulated twenty-four pots with low and high densities of radishes and collards in an intraspecific and interspecific competition setting. The purpose for conducting this experiment is gain a better understanding of how organisms in the wild interact with each other and affect other individual’s growth and overall fitness. Due to having some pots with intraspecific competition and interspecific competition, two hypotheses were formulated. In the intraspecific setting, we hypothesized that both species, the radishes and collards, would achieve higher leaf weight in the low density pots. The low density results in less competition for resources, allowing for a higher per capita benefit for each individual (in this scenario, leaf weight). In the interspecific competition setting, we hypothesized that the radishes would experience greater leaf weights and success (number of surviving individuals) in the low and high density setting because of possessing a stem that is longer than collard stems. Due to the longer stem, the radishes would have access to more sunlight than the collards. Interactions between the radishes and collards displays how fitness is impacted by the presence of competitors, which, we as humans, can use to maximize the survival and growth of mass produced crops.
Materials and Methods The organisms used in the experiment were Raphinus sativa (radish) and Brassica oleracae (collards). The experiment was setup in the USC Greenhouse, and utilized twenty-four pots. Each pot was filled tightly with soil, then the seeds of the radishes and collards were dispersed evenly within each pot. In the low density intraspecific pots, we placed eight seeds of radishes or collards in the soil. In the high density intraspecific pots, we placed sixty-four seeds of radishes or collards in each pot. In the low density interspecific pots, we placed four seeds each of collards and radishes together. Lastly, in the high density interspecific pots, we placed thirty-two seeds each of radishes and collards together. For each of these pot settings, there were four replicates, making a total of twenty-four pots. After placing the seeds evenly throughout the surface of the soil, about one centimeter of soil was lightly applied to the top layer to cover the seeds. Next, the pots were labeled according the setting (interspecific/intraspecific) and whether they were of high or low density. Following labeling the pots, they were each placed together in the greenhouse for six weeks and taken care of by the lab instructor. After the six weeks expired, the groups gathered together at the greenhouse for collection of the data. The plants were removed from the soil by carefully pulling them at the base of the stem, being sure to not separate the stem from the roots. The total number of successes (surviving plants) was recorded for each pot after being pulled from the dirt. Dirt remaining on the roots was washed away, and the underground biomass of the roots was recorded for each individual of each species, in each setting. In all settings, the data for each individual was recorded except for the stem length, where an average of five stems from each setting was recorded to get an estimation of the true stem length. Aside from underground biomass, other data collected for each individual included total leaf weight, number of leaves, and stem weight. The collected data was then normalized, and for the hypotheses of this experiment, the normalized areas were the proportion of survivors (number of plants/number of seeds planted) and the average leaf weight (total leaf weight/total number of leaves). After normalizing the data, an ANOVA analysis was performed on the data using Microsoft Excel, for both species in order to see the relationship between mechanisms, survival, and leaf weight. The single factor analysis was used for intraspecific pots to compare the leaf weights between the two species at high and low densities. Similarly, the two factor analysis was used for the interspecific setting to calculate the effects of the species on one another at high and low densities. Based on the results of the ANOVA analyses, conclusions could be drawn about if the density and competition with the same or different species affected the survival and growth of leaves. The ANOVA generated a P-value (less than 0.05 rejects the null hypotheses) which would then confirm whether or not there was a significant difference in the interspecific and intraspecific settings, as well as the high and low density settings, for leaf weight and survival.
Results
The average weights of the leaves for radishes and collards was used for comparison in the intraspecific setting. Table 1 shows the single factor ANOVA for the radishes in low and high density, which produced a P-value of 0.483193. The experiment’s α-level was set to 0.05, showing that high density collards achieved greater leaf weight. Graph 1 displays the average leaf weight in a more visual way.
ANOVA: Single factor analysis for radish leaf weight in low and high densities
ANOVA
Source of Variation
SS
df
MS
F
P-value
F crit
Between Groups
0.189244
1
0.189244
0.504085
0.483193
4.170877
Within Groups
11.2626
30
0.37542
Total
11.45185
31
Table 1: Single Factor ANOVA analysis of the average leaf weight (grams) for radishes in a low and high density intraspecific setting.
Graph 1: The average leaf weight of the radishes can be seen to be much higher in the high density setting, not supporting the hypothesis.
The collard leaf weight was also recorded (grams), and another single factor ANOVA analysis was performed to provide more information. The P-value in this analysis was 0.903093, again much higher than the α-level. Table 2 summarizes the analysis of the collard leaf weight in high and low densities. Graph 2 also displays visually, the difference in the average leaf weight of the collards. Although the average leaf weight is ever so slightly higher in the low density setting, it is not significantly higher (0.04462 grams in low density as compared to 0.04346 grams in high density).
ANOVA Single factor analysis for collard leaf weight in low and high densities
ANOVA
Source of Variation
SS
df
MS
F
P-value
F crit
Between Groups
1.1E-05
1
1.1E-05
0.015077
0.903093
4.170877
Within Groups
0.021868
30 …show more content…
0.000729
Total
0.021879
31
Table 2: ANOVA Single factor for collards at low and high densities (leaf weight) yielded a P-value of 0.903093.
Graph 2: The average leaf weight for the low density setting is slightly higher than high density setting in collards, but not significantly different.
In the interspecific competition settings, a two factor ANOVA analysis was performed (Table 3). For the leaf weights, three different P-values were generated. The P-value for the species section was 0.344904, indicating there is not a significant difference between the species in the interspecific setting. For the density section, 0.680005 was the obtained P-value which indicates that in the interspecific competition setting, there is no difference based on high and low density—the outcome would be the same in either situation. For the interaction section, the P-value given by the ANOVA was 0.826446, which essentially means there is no relationship between high and low density pots versus the type of species. In Graph 3, the average leaf weight for collards and radishes in the high and low density interspecific setting is visualized.
ANOVA: Two-Factor with replication for radish and collard leaf weight at low and high densities
Source of Variation
SS
df
MS
F
P-value
F crit
Species
0.001393
1
0.001393
0.90635
0.344904
4.001191
Density
0.000264
1
0.000264
0.171789
0.680005
4.001191
Interaction
7.46E-05
1
7.46E-05
0.048497
0.826446
4.001191
Within
0.09224
60
0.001537
Total
0.093972
63
Table 3: Two Factor ANOVA analysis generated P-values for each of density, interaction, and species for interspecific competition versus leaf weight. All P-values proved to be insignificant in light of the hypothesis, with α-level of 0.05.
Graph 3: the graph displays that there is not a significant difference in low and high densities of the mixed species pots, further failing to reject the null hypothesis.
For the survival of the single-species (intraspecific) setting, a single factor ANOVA analysis was performed again. For the radishes, Table 4 displays the results: with a P-value of 2.08 x 10-11, it is clear that the low density radish plants in the intraspecific competition survived enormously better than the high density radishes. Graph 4 displays the extremely noticeable difference in the low density versus high density intraspecific survival of the radishes.
ANOVA: Single Factor analysis for radish survival in the Low/High Density Intraspecific setting
Source of Variation
SS
df
MS
F
P-value
F crit
Between Groups
2.11087
1
2.11087
106.9293
2.08E-11
4.170877
Within Groups
0.592224
30
0.019741
Total
2.703094
31
Table 4: single factor ANOVA analysis of radishes in the intraspecific setting yielded a P-value of 2.08 x 10-11, which is extremely small in comparison to the α-level of 0.05.
Graph 4: the survival of the radishes in the low density setting can be seen defeating the high density setting by almost as much as 3x the number of survivors (0.8359375 as compared to 0.3222656).
For collards in the intraspecific setting, another single factor ANOVA analysis was performed to compare the number of survivors in the low and high density setting. Table 5 displays the results that were produced as a result: a very small P-value at 0.000284 indicates that the survival of collards in the low density single-species setting was much greater than the high density setting. Graph 5 also visually displays how well the low density intraspecific setting of collards fared as compared to the high density setting.
Anova: Single Factor analysis for collard survival in low/high density intraspecific setting
Source of Variation
SS
df
MS
F
P-value
F crit
Between Groups
0.293091
1
0.293091
16.86885
0.000284
4.170877
Within Groups
0.52124
30
0.017375
Total
0.814331
31
Table 5: the single factor ANOVA for the collards in the intraspecific setting generated a P-value of 0.000284, significantly smaller than the α-level.
Graph 5: the survival of the collards in the low density setting can be seen at about 3x greater success than the high density setting for intraspecific competition.
Lastly, another two factor ANOVA analysis was performed in terms of the success (survival) of the plants in the interspecific setting. Table 6 displays the species P-value generated by the ANOVA was 0.021921, indicating there is a significant difference in the survival of radishes and collards in the interspecific setting. The density P-value, 1, is extremely large and shows there is no difference whether or not the plants are in a high density or low density area when in mixed-species pots. Finally, the interaction P-value was also higher than the α-level of 0.05, at 0.679457, again indication there is no relationship between the low and high densities versus the plants species. Graph 6 displays the survival of the mixed-species setting at both the low and high density settings.
ANOVA: Two-Factor With Replication for radish and collard survival at low and high densities
Source of Variation
SS
df
MS
F
P-value
F crit
Species
0.282227
1
0.282227
5.536398
0.021921
4.001191
Density
0
1
0
0
1
4.001191
Interaction
0.008789
1
0.008789
0.172414
0.679457
4.001191
Within
3.058594
60
0.050977
Total
3.349609
63
Table 6: a two factor ANOVA analysis was performed for the survival of the plants, and indicated that the P-value for the species section was the only significant difference (0.021921), meaning that there was a difference in the survival of radishes versus collards. However, the P-value for density and interaction proved to be insignificant.
Graph 6: the survival of the mixed-species pots at high and low densities is displayed, showing that at low densities the radishes survived better and at high densities, the collards had higher survival.
Discussion In the intraspecific setting, we must reject our hypothesis that both the low density collards and radishes would achieve greater leaf weight. Based on the ANOVA analysis, the generated P-values for the radishes and collards were 0.483193 and 0.90309, respectively. Both values were above the α-level of 0.05, so the hypothesis must be rejected. Although the low density setting did not yield a greater leaf weigh than the high density condition, the survival of the radishes and collards in the low density intraspecific setting was significantly higher. The P-values were 2.08 x 10-11 and 0.000284 for the radishes and collards, respectively. These generated values are extremely small in comparison to the α-level of 0.05, indicating that the survival was much greater for both species in the low density intraspecific setting. In the interspecific setting, part of the hypothesis is rejected. For the leaf weight, we predicted it would be higher in the lower density mixed-species setting, however the generated P-values proved otherwise. For species, density, and interaction, they respectively were 0.344904, 0.680005, and 0.826446, all of which are much higher than the α-level. However, for the survival of the radishes versus the collards, the hypothesis was not rejected. In the mixed-species setting at both low and high density settings, the radishes had better success at surviving, as indicated by the ANOVA analysis with a P-value of 0.021921. The density P-value (1.000) did not prove to be significant, and neither did the interaction P-value (0.679457). Nonetheless, it is confirmed that the radishes do experience greater survival in the interspecific competition as compared to the collards, regardless of high or low density. Also, it is important to note that the success of collards in the interspecific setting was approximately the same for low and high density, seemingly doing better than when in the intraspecific setting (e.g. high density intraspecific collard survival was 0.105 while the high density interspecific collard rose to 0.273). From the results, it appears that the average leaf weight of the radishes and the collards shows an increase in the interspecific setting. Based on this, it is plausible to think that the two species should be grown together for agricultural purposes—higher leaf weight means the plant is thriving more. The rationale for this is due to intraspecific competition being more intense than interspecific competition, as stated before. When radishes or collards are competing within their species, they are all thriving for the same exact resources, making the competition more intense (Ricklefs, 2013). However, when grown interspecifically, the two species do not require the exact same resources, therefore the competition for resources is not so intense (Jones, 2014). From this, the intraspecific competition is obviously more intense than interspecific competition, which is what allowed for the two species to thrive together in the same pot and achieve a higher survival and leaf weight in the interspecific setting (Aguiar, 2001). Although the results came out in an unforeseen manner, they may be attributed to human error. It was mentioned to the groups that there was a malfunction in the schedule watering of the plants, due to the sprinkler system not working. This caused many plants to face drought-like conditions, inhibiting the growth and survival with almost entire certainty. Due to this, it cannot be stated with full confidence that these results are a fine depiction of what would really happen. However, due to this experiment being under drought-like conditions, a possible future experiment could be in flood-like conditions (inundation). If the radishes achieved higher leaf weight and survival in the mixed-species setting in drought-like conditions, perhaps the collards will benefit more in conditions with excessive water. Using the same experimental setup, replicate the procedure but add excessive amounts of water daily. Lastly, this experiment has provided valuable information on how the collard and radish species interact and affect the fitness of the competitors they are surrounded by. Based on this, we can proceed forwards with implementing the results into real practices of agriculture. Production of crops can be maximized and inversely, waste production will be minimized. In the growing world population, every last bit counts, therefore, knowing how these species grow best can have incredible effects on our hungry planet.
Acknowledgements
In this experiment, I thank all of my group partners. Tylar Lee, Owen Smith, Bradyn Holaus, and Joshua Haney. Each of them worked equally as hard as I did in completing the experiment and compiling the data. Also, I thank our lab instructor, Jen Fill, for providing every group with extra help and tips to complete the experiment properly.
References
1. Aguiar, M. R., Lauenroth, W. K., & Peters, D. P. (2001). Intensity of intra- and interspecific competition in coexisting shortgrass species. Journal of Ecology, 89 (1) Pp.40-47, 2001, Retrieved from http://search.proquest.com/docview/925275438?accountid=13965
2. Fill, J. (2014). Interspecific and Intraspecific Competition (Handout). Retrieved from https://blackboard.sc.edu 3. Gustafsson, L. (1987). Interspecific competition lowers fitness in collared flycatchers ficedula albicollis: :An experimental demonstration. Ecology, 68(2), 291-296. Retrieved from http://search.proquest.com/docview/14677246?accountid=13965
4. Jones, C. B. (2014). The Evolution of Mammalian Sociality in an Ecological Perspective, 13.
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6. Ricklefs, R., & Relyea, R. (2013). Ecology: The Economy of Nature (7th ed.) (369). New York, NY: W. H. Freeman and Company