Reproductive interference across continental scales: combining citizen science and behavioural experiments to test reproductive character displacement hypotheses

Overview

Behavioural interactions between species impact numerous ecological and evolutionary processes [1-3]. For instance, wasteful reproductive interactions between species (“reproductive interference”) may prevent two species from coexisting in the same location unless natural selection drives divergence in traits used as mating signals [4]. Demoiselle damselflies (Figure 1) are a model system for studying the evolutionary consequences of sexual interactions between species [5-8]. Yet, despite the fact that male damselflies initiate mating interactions, there has been little research into the mechanisms by which variation in female wing colour impacts male sexual responses. Consequently, there remains much unexplained variation in causes and consequences of reproductive interference, even in this model system. To address this gap in our understanding of how male and female behaviour and sexual signals impact the dynamics of reproductive interference, this project will employ a unique combination of behavioural experiments on damselflies in the UK and abroad, public engagement through citizen science, and cutting-edge artificial intelligence (AI) methods.

Click on an image to expand

Image Captions

Figure 1: (Top) Banded demoiselle (Calopteryx splendens) tandem pair and (bottom) Beautiful demoiselle (C. virgo) copulatory wheel. Photo credits: J. Drury (top) & P. Ritchie (bottom)

Figure 2: Screenshot of British Demoiselles project page in the iNaturalist smartphone app.

Methodology

If reproductive character displacement—that is, selection to diminish the occurrence of wasteful reproductive interactions between species [9]—has acted on female wing colour and/or male mate recognition, between-species differences in female wing colour and/or male ability to discriminate between conspecific and heterospecific females will be more pronounced where the two species coexist. To test these predictions, the student will collect data at several sites across a network of sympatric and allopatric sites, in the UK and/or continental Europe. At each site, the student will (1) measure female wing colour using digital photography and reflectance spectroscopy, and (2) conduct behavioural experiments to measure male responses to conspecific and heterospecific females. To create a broad-scale map of female phenotypic variation, allowing for a more robust test of the reproductive character displacement hypothesis, the student will use a combination of measurements (e.g., reflectance spectra measurements and colour-calibrated photographs taken in the field [10]) to help develop a protocol for extracting data on female wing colour throughout each species’ range from citizen scientist photographs uploaded to existing citizen science schemes (e.g., iRecord, iNaturalist; https://www.inaturalist.org/projects/british-demoiselles; Figure 2). The student will also develop collaborations with citizen scientists through the British Dragonfly Society and other organisations, which have made it possible to test hypotheses about geographic variation in wing phenotypes on an unprecedented scale [11]. In parallel, the student may also contribute to the development of a complementary AI approach and design image recognition algorithms, using cutting edge Convolutional Neural Networks (CNNs) to determine whether species in sympatric populations are more visually distinctive, as predicted by the reproductive character displacement hypothesis.

Project Timeline

Year 1

Develop pipeline for analysing female phenotypes from photographs; analyses of citizen science dataset; fieldwork to collect phenotypic and behavioural data in the UK.

Year 2

Complete and submit female phenotype analysis for publication; conduct further fieldwork in continental Europe.

Year 3

Conduct additional local fieldwork as needed, run analyses of geographic variation in male mate recognition and write up thesis.

Year 3.5

Finish writing up thesis and prepare results for publication.

Training
& Skills

The student will receive training in (1) the objective, quantitative measurement and analysis of colour using both reflectance spectroscopy and photography, (2) field behavioural ecology techniques, and (3) analytical and computational skills.

References & further reading

1. Grether G, Peiman K, Tobias J, Robinson B. 2017. Causes and consequences of behavioral interference between species. TREE, 32, 760-772.
2. Gröning J, Hochkirch A. 2008 Reproductive interference between animal species. Q. Rev. Biol. 83, 257-282.
3. Shuker D, Burdfield-Steel E. 2017 Reproductive interference in insects. Ecol. Entomol. 42, 65-75.
4. Kuno E. 1992 Competitive exclusion through reproductive interference. Res. on Pop. Ecol. 34, 275-284.
5. Wellenreuther M, Tynkkynen K, Svensson E. 2010 Simulating range expansion: Male species recognition and loss of premating isolation in damselflies. Evolution 64, 242-252.
6. Svensson E, Nordén A, Waller JT, Runemark A. 2016 Linking intra- and interspecific assortative mating: Consequences for asymmetric sexual isolation. Evolution 70, 1165-1179.
7. Svensson E, Runemark A, Verzijden M, Wellenreuther M. 2014 Sex differences in developmental plasticity and canalization shape population divergence in mate preferences. Proc. R. Soc. B 281, 20141636. (doi:10.1098/rspb.2014.1636)
8. Honkavaara J, Dunn DW, Ilvonen S, Suhonen J. 2011 Sympatric shift in a male sexual ornament in the damselfly Calopteryx splendens. J. Evol. Biol. 24, 139-145.
9. Pfennig KS, Pfennig DW. 2009 Character displacement: Ecological and reproductive responses to a common evolutionary problem. Q. Rev. Biol. 84, 253-276.
10. Troscianko J, Stevens M. 2015 Image calibration and analysis toolbox – a free software suite for objectively measuring reflectance, colour and pattern. Methods Ecol. Evol. 6, 1320-1331.
11. Drury J, Barnes M, Finneran A, Harris M, Grether G. 2019 Continent‐scale phenotype mapping using citizen scientists’ photographs. Ecography. 42, 1436-1445.

Further Information

For more information, contact Dr Jonathan Drury, jonathan.p.drury@durham.ac.uk, 0191 3341348

Apply Now