Introduction -to- Ecology

A course covering population, community, and ecosystem ecology for undergraduates

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Graphing

Mass vs Metabolism


The relationship between the body size of an organism and its metabolic rate is one of the most well studied and still most controversial areas of organismal physiology. We want to graph this relationship in the Artiodactyla using a subset of data from a large compilation of body size data (Savage et al. 2004). You can copy and paste this data frame into your program:

size_mr_data <- data.frame(
  body_mass = c(32000, 37800, 347000, 4200, 196500, 100000, 4290, 
    32000, 65000, 69125, 9600, 133300, 150000, 407000, 115000, 
    67000,325000, 21500, 58588, 65320, 85000, 135000, 20500, 1613,
    1618),
  metabolic_rate = c(49.984, 51.981, 306.770, 10.075, 230.073, 
    148.949, 11.966, 46.414, 123.287, 106.663, 20.619, 180.150, 
    200.830, 224.779, 148.940, 112.430, 286.847, 46.347, 142.863, 
    106.670, 119.660, 104.150, 33.165, 4.900, 4.865))

Now make three plots with appropriate axis labels:

  1. A graph of body mass vs. metabolic rate
  2. A graph of log(body mass) vs. log(metabolic rate) (You can do this transformation inside the call to aes())
  3. A graph of body mass vs. metabolic rate, with logarithmically scaled axes (this is different from number 2), and the point size set to 5.

Think about what the shape of these graphs tells you about the form of the relationship between mass and metabolic rate.

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