Comparing the morphs with regard to hormone levels gives only limited information about causal mechanisms, however, and preliminary behavioral studies in males suggest that morph differences in plasma androgens do not completely explain morph differences in territorial aggression.
We used nestlings because they have already started to show morph differences at that age, and because adults are difficult to catch.
In damselflies morph differences in life history and related traits have hardly been studied.
Further studies are needed to disentangle these possibilities and to account for potential morph differences in plasticity of immune function as well.
Differences in immune function are unlikely to underpin fluctuating selection on polymorphism in the wild sensu [ 9], unless morph differences in life history [ 18] translate in to differences in immune function in the wild given the tenet that immunity in damselflies is plastic [ 27, 35].
To try and understand how this inter-morph difference in longevity evolved, we compared gene expression in long- and short-lived adults.
Female morphs in this system have apparently developed different ways to cope with male harassment, and these morph-differences can potentially explain rapid fluctuations in morph frequencies between years [15].
We compared the overall mating rates of the morphs, morph-differences in resistance towards mating attempts and the effects of realized matings and mating attempts on female fecundity.
The degree of morph, physical difference, and perceptual difference regressors (after convolution) were then multiplied by these coefficients.
The second order polynomial expansion of these regressors (degree of morph, physical difference, and perceptual difference) was included in our model.
Finally, open vs shaded habitat morph frequency difference shows positive and significant correlation with habitat and area age, leading to mean evolutionary rates of 14.7 (s.d. 20.7) and 31.4 (s.d. 45.2) kilodarwin (using polder age and habitat age, respectively).
