Biology Reference
In-Depth Information
(a)
(b)
(c)
Fig. 2.3
Differences in social organization of African ungulates. (a) Kirk's dik-dik
Madoqua kirki
live in pairs in
woodland. Photo © Oliver Krüger. (b) Impala live in small groups in open woodland and grassland. Photo © Bruce
Lyon. (c) Wildebeest graze in huge herds out on the open plains. Photo © iStockphoto.com/William Davies.
Limitations of early comparative studies
These early studies revealed the promise of the comparative approach in behavioural
ecology. However, there were limitations in the methodology. Many of these are not
unique to comparative studies and it is worth bearing them in mind throughout the topic.
(a)
Alternative hypotheses
The explanations for the differences in behaviour are certainly plausible, but alternative
hypothesis have not been considered in a rigorous manner. For example, the nest site
difference between the black-headed gull and kittiwake is also likely to be correlated
with differences in shelter, competition for nest sites and proximity to the feeding
grounds. How can we be sure that predation is the key selective pressure, rather than
one of these other variables?
Problems in
interpreting
comparative data
