Song and female choice for extrapair copulations in the sedge warbler, Acrocephalus schoenobaenus

Although 90% of passerine birds live in socially monogamous pair bonds, molecular studies have revealed that genetic polygamy occurs in 86% of surveyed passerines, because individuals engage in copulations outside the pair bond (extrapair copulations; EPCs). Most explanations for the occurrence of EPCs involve female gaining indirect benefits from the extrapair male. The sedge warbler is a socially monogamous species in which some offspring result from EPCs (8% in this study). Complex song is a sexually selected male trait used by females which select mates based on a variety of male qualities. We used microsatellite DNA profiling to detect extrapair young and assign paternity. ‘Good genes’ theory predicts that females should engage in EPCs with males of higher quality than their social mate, with resulting fitness benefits. Extrapair males had smaller song repertoires and smaller territories than the social mate. This apparent preference for small-repertoire males as extrapair mates conflicts with the predictions from previous studies of this species. Sudden cessation of song after pairing may mean that song cues are unavailable for later extrapair matings and females may switch to other cues. Such behaviour may lead to different patterns of female choice during social and extrapair mating in the sedge warbler. We conclude that multiple reasons underlie patterns of female choice in this species.

The effects of familiarity and group size on mating preferences in the guppy, Poecilia reticulata

In recent years, it has become evident that frequency dependence in the attractiveness of a particular phenotype to mates can contribute to the maintenance of polymorphism. However, these preferences for rare and unfamiliar male phenotypes have only been demonstrated in small, controlled experiments. Here, we tested the preference for unfamiliar mates in groups of six to 96 individuals over 13 days, in the guppy (Poecilia reticulata). We observed individual behaviour in situ to test whether fish discriminate two unfamiliar individuals among many familiar ones. We found that unfamiliar males and females were preferred over the familiar fishes in all groups and that this effect decayed over time. Increasing group sizes and levels of sexual activity did not hamper the preference for unfamiliar mates, providing further support for the role of frequency dependent mate choice in the maintenance of trait polymorphism in natural populations.

Interview with Nina Nurmila

Nina Nurmila is an Indonesian who studied at Murdoch University in 1995-1997 and at Melbourne University in 2002-2007, and in 2008. Her first two periods of study were on Australian Development Scholarships (ADS) and she completed a Masters degree at Murdoch and a PhD at Melbourne, both in Development Studies. Her PhD thesis was about polygamy in Indonesia and she spent some of this study period (2002-2007) in Indonesia. In 2008 she returned to Australia on a post-doctorate Endeavour Scholarship. The interview was conducted in English on 30 April 2014 by Dr. Jemma Purdey of Deakin University and Dr. Ahmad Suaedy of the Abdurrahman Wahid Centre for Inter-faith Dialogue and Peace at Universitas Indonesia. This set comprises: an interview recording, a timed summary, and a photograph.