Study design and Statistical methods - Mathematics and Quantitative Ecology - Ecology and Evolution Previous Year Questions

1

2014 · Ecology and Evolution · Mathematics and Quantitative Ecology · Study design and Statistical methods

Ecology and Evolution (EY) 2014

A researcher tested for the presence of parasitic infection in 100 male and 100 female deer. Forty males and 30 females were found to be infected. To test if males are significantly more susceptible to infection than females, which of the following is an appropriate statistical test?

A

Student's t-test

B

Mann-Whitney U test

C

Chi-square test

D

Correlation test

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2

2014 · Ecology and Evolution · Mathematics and Quantitative Ecology · Study design and Statistical methods

Ecology and Evolution (EY) 2014

A student wants to test the effect of latitude and longitude on seed size in a plant species. He has the resources to lay a maximum of 9 plots. Which plot designs most appropriate for this question?

A

A

B

B

C

C

D

D

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3

2014 · Ecology and Evolution · Mathematics and Quantitative Ecology · Study design and Statistical methods

Ecology and Evolution (EY) 2014

A study monitored insect abundance and drought stress in trees for a period of 10 years in a tropical dry deciduous forest. This study found a strong, statistically significant, negative relationship between insect abundance and drought stress in trees. Based on these results, what can be inferred about the causal relationship between insect abundance and drought stress in trees?

A

Increased insect abundance causes increased drought stress in trees

B

Increased drought stress in trees causes increase in insect abundance

C

Decreased drought stress in trees causes increase in insect abundance

D

No direct causal relationship can be inferred from these data

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4

2018 · Ecology and Evolution · Mathematics and Quantitative Ecology · Study design and Statistical methods

Ecology and Evolution (EY) 2018

Which of the following can be used to test differences between mean tree heights in a tropical versus a temperate forest?

A

Binomial test

B

Linear regression

C

Pearson’s correlation

D

Student’s t-test

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5

2019 · Ecology and Evolution · Mathematics and Quantitative Ecology · Study design and Statistical methods

Ecology and Evolution (EY) 2019

A researcher wants to sample ant diversity in a landscape consisting of riverine valleys and plateaus. Which among the following is the best sampling strategy for her to employ?

A

Once an ant is located, lay quadrats in that area

B

Lay equal number of quadrats in valleys and plateaus

C

Lay quadrats in areas of high ant abundance

D

Lay quadrats in both habitats in proportion to their areas

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6

2019 · Ecology and Evolution · Mathematics and Quantitative Ecology · Study design and Statistical methods

Ecology and Evolution (EY) 2019

A teacher proposed a null hypothesis (H0) that there is no difference in the mean heights of boys and girls in his class. His alternative hypothesis (Ha) was that boys are taller than girls.
The figure below shows the probability distribution, i.e. probability density function, of the difference in the mean height of boys and girls if the null hypothesis were true. The observed mean difference in heights is shown by the solid black circle. The dotted line represents the range μ ± 2σ whereas the solid line shows the range μ ± 3σ.
Assuming a significance level of 0.05, which of the following conclusions is correct?

A

H0 is accepted

B

H0 is rejected

C

Ha is accepted

D

Ha is rejected

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7

2020 · Ecology and Evolution · Mathematics and Quantitative Ecology · Study design and Statistical methods

Ecology and Evolution (EY) 2020

Analysis of variance (ANOVA) can be used to compare multiple groups of samples. Select the correct option that reflects the principle behind ANOVA.

A

The sum of the squares of the variances is calculated for the groups being compared.

B

The variance ratio is calculated by subtracting each value from the overall mean, squaring the difference, and summing the resulting squared deviations.

C

The variation between groups is compared with the variation within groups.

D

The F value is statistically significant if the mean values between the groups are the same.

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8

2021 · Ecology and Evolution · Mathematics and Quantitative Ecology · Study design and Statistical methods

Ecology and Evolution (EY) 2021

The table shows a list of analysis goals (i, ii, iii) and different statistical tests (P, Q, R).

(i) Comparing mean body size of three samples of snakes, each from a different population	(P) Chi-square test
(ii) Testing if two continuous traits are linearly associated	(Q) Analysis of Variance
(iii) Testing if a plant species shows Mendelian inheritance of flower colour (red, white)	(R) Correlation coefficient

Match the analysis goal to the most appropriate statistical test.

A

(i)-(P), (ii)-(R), (iii)-(Q)

B

(i)-(Q), (ii)-(P), (iii)-(R)

C

(i)-(Q), (ii)-(R), (iii)-(P)

D

(i)-(R), (ii)-(Q), (iii)-(P)

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9

2021 · Ecology and Evolution · Mathematics and Quantitative Ecology · Study design and Statistical methods

Ecology and Evolution (EY) 2021

All octopi dream every night, and sometimes change colour while dreaming. A student hypothesises that octopi change colour only when they dream about the food they ate that day. To test this hypothesis, the student conducts an experiment with two treatments that are randomly ordered, and separated by 2 days. In one treatment, she places 10 octopi in individual tanks in captivity and provides each one with a large crab to eat during the day. She then records the dream state colour of these octopi that night. Which one (or more) of the following would be an appropriate NEGATIVE control to test this hypothesis?

A

Provide the same 10 octopi with the same food source (crab), and then record their colour that night when they are dreaming.

B

Provide the same 10 octopi with a new food object (e.g. sea stars) and record the colour that night when they are dreaming.

C

Provide the same 10 octopi with a non-food object (e.g. rock), and record their colour that night when they are dreaming.

D

Provide 10 squid with the same food source (crab) and record the colour that night when they are dreaming.

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10

2024 · Ecology and Evolution · Mathematics and Quantitative Ecology · Study design and Statistical methods

Ecology and Evolution (EY) 2024

An ecologist must determine whether
(i) the means of two independent samples differ, and
(ii) there is an association between two continuous variables.
Assuming that all samples are normally distributed, which one of the following options represents the most appropriate statistical tests for (i) and (ii), respectively?

A

(i) Spearman’s correlation; (ii) Shapiro-Wilk test

B

(i) Wilcoxon’s matched pairs signed rank test; (ii) chi-squared test

C

(i) t-test; (ii) Pearson’s correlation

D

(i) Kendall’s test of concordance; (ii) Kolmogorov-Smirnov test

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11

2025 · Ecology and Evolution · Mathematics and Quantitative Ecology · Study design and Statistical methods

Ecology and Evolution (EY) 2025

The table below provides a list of study questions (P, Q, R) and statistical tests (i, ii, iii).

Study question	Statistical Test
(P) Does flower colour follow Mendelian inheritance?	(i) Student's t-test
(Q) Does increased visitation by pollinators increase the number of viable fruits produced by an individual?	(ii) Chi-square test
(R) Does the quantity of nectar production differ between flowers that were visited by pollinators compared to those that had no pollinator visitation?	(iii) Pearson's correlation analysis

Which one of the following options correctly matches the study question to the most appropriate statistical test?

A

P-i; Q-ii; R-iii

B

P-i; Q-iii; R-ii

C

P-ii; Q-i; R-iii

D

P-ii; Q-iii; R-i

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12

2016 · Ecology and Evolution · Mathematics and Quantitative Ecology · Study design and Statistical methods

Ecology and Evolution (EY) 2016

Today, we consider Ashoka as a great ruler because of the copious evidence he left behind in the form of stone carved edicts. Historians tend to correlate greatness of a king at his time with the availability of evidence today.
Which of the following can be logically inferred from the above sentences?

A

Emperors who do not leave significant sculpted evidence are completely forgotten.

B

Ashoka produced stone carved edicts to ensure that later historians will respect him.

C

Statues of kings are a reminder of their greatness.

D

A king’s greatness, as we know him today, is interpreted by historians.

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13

2023 · Ecology and Evolution · Mathematics and Quantitative Ecology · Study design and Statistical methods

Ecology and Evolution (EY) 2023

To test whether body size differs between two populations of a field mouse species, a researcher measured 100 individuals in each population and calculated the statistic \[ \frac{\bar{X}_1 - \bar{X}_2}{S_p \sqrt{\frac{1}{n_1} + \frac{1}{n_2}}} \] where \(\bar{X}_1\) and \(\bar{X}_2\) are the mean body sizes of the two populations, respectively, \(S_p\) is the pooled standard deviation, and \(n_1\) and \(n_2\) are the sample sizes for the two populations, respectively.
This statistic is used in the

A

Chi-square test

B

Kruskal-Wallis test

C

Student's t-test

D

Mann-Whitney U test

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