Organized Symposium

Sex and ecological communities

14 November｜16:15〜18:15 ｜Language- English

Sex and ecological communities

A variety of phenomena related to sex, including sexual selection, mating behavior, and sex ratio, have been studied to understand the way conspecific individuals interact with one another. Emerging evidence suggests, however, that sex-related phenomena affect not just intra-, but also inter-specific interactions. In some cases, the effects of sex-related phenomena on inter-specific interactions can be so strong as to modify the structure and function of the entire community to which the focal species belongs. In turn, communities can define the ecological context in which sexual traits evolve. In this symposium, speakers will present some new findings on connections between sex and ecological communities. We hope that this symposium will help to identify promising directions for future research.

Organizer: Dr. TSUJI Kaoru, Dr. YAMAMICHI Masato

Linking community ecology to sexual selection and sexual conflict: insights from field studies and experiments with damselflies (Zygoptera)

Erik Svensson (Lund University)

There is an increasing interest in linking community ecology to evolutionary biology and behavioural ecology, reflected in growing fields and popular topics such as reproductive interference, reproductive isolation, speciation and extinction dynamics and sexual selection. Moreover, the field of community ecology has matured and is becoming increasingly similar to evolutionary biology by focussing on a few central mechanisms, similar to population genetics, as reflected in Vellend’s Theory of Ecological Communities, Hubbell’s Neutral Theory of Biodiversity and Chesson’s concepts of stabilizing and equalizing mechanisms. Here, I discuss these developments and connect this to recent empirical and theoretical work in my laboratory, using damselflies (Zygoptera) as our model organisms. In particular, I aim to link interspecific interactions and co-existence mechanisms to the similar processes operating within species. I will also discuss negative frequency-dependence as a general mechanism maintaining both species diversity in communities and genetic diversity within populations.

Coexistence theory with eco-evolutionary dynamics of sex

YAMAMICHI Masato (University of Queensland）

How does rapid evolution of sexual traits affect species coexistence? First, I explain how reproductive interference hinders species coexistence via positive frequency-dependence in community dynamics. This can be weakened by reproductive character displacement, but theoretical studies suggest that the amount of genetic variation is crucial for the completion of displacement as slow evolution results in deterministic extinction. Then, I introduce a new concept, intraspecific adaptation load, to explain how an adaptation to conspecific conflicts can promote species coexistence by negative frequency-dependence in community dynamics. More abundant species is more susceptible to invasion of 'selfish' individuals that increase their own reproductive success at the expense of population growth, and the density-dependent intraspecific adaptation load stabilizes species coexistence.

Microbes on flowers and pollination

SAKAI Shoho (Kyoto University)

The flower is the device by which plants exchange their pollen. It has nectar, structures to receive pollinator visits and wind, and a germination bed for pollen grains. These characteristics may make the flower vulnerable to microbial infection. How have microbes on flowers affected plant ecology and evolution? In this talk, I will show part of our ongoing studies on bacterial flora on flowers and effects of bacteria inoculation to flowers on the plants. I also discuss how floral microbes can change our views on pollination and plant sexual systems.

Community-wide consequences of sexual dimorphism in floral traits

TSUJI Kaoru (Kyoto University)

Female and male individuals belonging to a sexually dimorphic species can interact with heterospecific individuals differently. Although intuitive, evidence demonstrating this possibility remains scarce. Focusing on the dioecious plants Eurya japonica and E. emarginata, I will present evidence showing that sexual dimorphism in floral traits exerts surprisingly large effects on the behavior of flower-visiting flies, bees, and other insects, the survival, growth, and evolution of oviposition behavior of flower-feeding moths, and the abundance and community structure of nectar-inhabiting bacteria and yeasts. The resulting changes in the insects and microbes can in turn affect the evolution of floral traits and the reproductive success of the flowers. These findings show how wide-ranging the effects of sexual dimorphism can be in ecological communities.

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