Hey everyone

My name is David Clarke and I have decided to make the main topic of my blog sexual selection throughout the animal kingdom.  It will include many facets that include evolution, sexual dimorphism and the variety of mate finding behaviour that is utilised by different species. My plan is to give an example of sexual selection from a different species each week with information taken from the literature.

For this first post I thought, seeing as though this is an evolution class, I would start with an example from back in the Jurassic, which is also an example of a very simple way of attracting females (in animals), showing off your enlarged genitalia. In this instance it is an extinct insect in the order Mecoptera that existed in the late Middle Jurassic.

Scientists discovered the fossils of two, now new, genera of scorpionfly in the Jiulongshan formation at Daohugou village Ningcheng County in Inner Mongolia, China. Through examinations of the specimens they found that, although similar in size to other Mecopterans in the same era, these new specimens, Miriholcorpa forcipata (Figure 1) and Fortiholcorpa paradoxa (Figure 2) had enlarged male genitalia and extremely long and extended terminal abdominal segments.

The scientists proposed an evolutionary scenario in which these abdominal segments were used to intimidate/compete with other males and/or were used to attract females by showing off their large “penis”. Having these large abdominal segments and  enlarged genitalia could be seen to be quite a burden to carry around however as  they were alive for quite a while  it is thought that the sexual selection and display of these characteristics outweighed the possible poor mobility and bulky body plan in the evolutionary process.

Figure 1 - Photograph and line drawing showing abdominal segments on Miriholcorpa forcipata   Figure 2 - Photograph and line drawing showing abdominal segments in Fortiholcorpa paradoxa  References

ANG, Q., SHIH, C. & REN, D. 2013. The Earliest Case of Extreme Sexual Display with Exaggerated Male Organs by Two Middle Jurassic Mecopterans. PloS one, 8, e71378.