Figure 1.
The allometric relationship between the brain and body sizes in 1309 mammalian species.
Because the families were represented by an unequal number of data points (species), each family was given an equal weight when calculating the ordinary least-square regression. This correction for biased representation of the families resulted in a line seemingly unfitting the data points (representing species and not families). This adjusted regression line is considerably more reliable for further GLM analyses performed between family level, though. Allometric equation: ln(brain mass) = −0.6601 * ln(body mass)−2.4100.
Figure 2.
The pictures of the representatives of the family Felidae (the second most preferred family out of 123 examined ones).
It illustrates the variation of body positions among four tested sets of pictures (for details see under Materials and Methods): clouded leopard Neofelis nebulosa (top left), serval Leptailurus serval (top right), jaguar Panthera onca (bottom left; pictures painted by Silvie Lišková) and caracal Caracal caracal (bottom right; photo from the archive of the Zoo Prague).
Figure 3.
The proportion of zoo species as predicted by GLM.
The effects of species richness (a), brain size (b), body size (c), and attractiveness (d). The dependent variable is the number of species kept in WZC scaled to the total number of extant species of a given family. This binomial variable reflects the mean probability that a species is kept in at least one zoo. For the definition and transformation of the explanatory variables see under the Material and methods section.
Table 1.
The parameters of the reduced general linear models examining the effects of species richness, body size, brain size and attractiveness on dependent variables reflecting the representation of mammalian species in WZC.
Figure 4.
The effects of body size and attractiveness.
The effects of body size and attractiveness on the mean population size (a,b), number of zoos (c,d) and number of conspecifics per zoo (e,f). The mean population size: The world zoo population size (square-root transformed) per species present in WZC. The number of zoos: The natural log-transformed mean number of zoos keeping the species. The number of conspecifics per zoo: The mean number of conspecifics per zoo keeping the species. The families not represented in WZC were excluded from the analyses. For the definition and transformation of the explanatory variables see under the Material and methods section.