Andromorphism
Andromorphism is the condition where some females look like the males; what possible advantage can there be. If you look like a male then surely you are less likely to be attractive and therefore less likely to mate; but is that the case?
Boyeria irene – This common European hawker is found along shady rivers; the sexes look very similar but the female comes in two forms:
Aeshna cyanea – The males are predominantly blue (abdomen) whilst the females are green. I saw my first “blue” female only recently. I contacted Bryan Pickess down in Dorset, who was surprised as the blue female is quite common there.
Boyeria irene – This common European hawker is found along shady rivers; the sexes look very similar but the female comes in two forms:
- Form typica - long upper anal appendages
- Form brachycera – short upper anal appendages
Aeshna cyanea – The males are predominantly blue (abdomen) whilst the females are green. I saw my first “blue” female only recently. I contacted Bryan Pickess down in Dorset, who was surprised as the blue female is quite common there.
Lestids in Europe
I was in Spain in 2011 on one of my favourite ponds. I found Lestes sponsa in abundance, could be 50,000 individuals and my first andromorph female (pic).
In UK, females with blue eyes are common but I I have never seen a full andromorph as I did in Spain. Since then I have found andromorphs quite often in Spain. In Jodicke’s book on Lestidae, he states that andromorph L. sponsa are very rare in Europe and only recorded from the Alps. L. sponsa is found right across the Palearctic into Japan where, I understand, andromorphs are common. As for central Europe, Dave Smallshire sent me a picture taken in Estonia of a full andromorph female
What about other Lestids? Lestes dryas females often have blue eyes but no other andromorph features have ever been recorded.
More questions here:
I was in Spain in 2011 on one of my favourite ponds. I found Lestes sponsa in abundance, could be 50,000 individuals and my first andromorph female (pic).
In UK, females with blue eyes are common but I I have never seen a full andromorph as I did in Spain. Since then I have found andromorphs quite often in Spain. In Jodicke’s book on Lestidae, he states that andromorph L. sponsa are very rare in Europe and only recorded from the Alps. L. sponsa is found right across the Palearctic into Japan where, I understand, andromorphs are common. As for central Europe, Dave Smallshire sent me a picture taken in Estonia of a full andromorph female
What about other Lestids? Lestes dryas females often have blue eyes but no other andromorph features have ever been recorded.
More questions here:
- Does the andromorph form of L. sponsa occur in UK?
- Why, if it occurs in L. sponsa, does it not occur in L. dryas ?
Theory – Females only need to mate once; they can store sperm. Males must mate to spread their genes. Where populations are large, females will have no problem finding a mate indeed the opposite is the case; they will be pestered and try to avoid contact with males. Female Aeshnids often freeze their wings when they are ovipositing so that passing males do not spot them. Females of Somatochlora metallica keep away from the water until the sun goes in or until late in the day when the males have left the water, before coming to oviposit.
Perhaps looking like a male can inhibit mating activity and can be an advantage to females in large populations.
Perhaps looking like a male can inhibit mating activity and can be an advantage to females in large populations.