The consequences of sexual selection
in well-adapted and maladapted
populations of bean beetles
and David Berger
Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Sweden
Department of Evolutionary Biology, Institute for Biological Research “Sini
c” University of Belgrade, Bulevar
despota Stefana 142, Belgrade 11060, Serbia
Institute of Zoology, Faculty of Biology, University of Belgrade, Studentskitrg 16, Belgrade 11000, Serbia
Received June 30, 2017
Accepted December 3, 2017
Whether sexual selection generally promotes or impedes population persistence remains an open question. Intralocus sexual
conﬂict (IaSC) can render sexual selection in males detrimental to the population by increasing the frequency of alleles with pos-
itive effects on male reproductive success but negative effects on female fecundity. Recent modeling based on ﬁtness landscape
theory, however, indicates that the relative impact of IaSC may be reduced in maladapted populations and that sexual selection
therefore might promote adaptation when it is most needed. Here, we test this prediction using bean beetles that had undergone
80 generations of experimental evolution on two alternative host plants. We isolated and assessed the effect of maladaptation
on sex-speciﬁc strengths of selection and IaSC by cross-rearing the two experimental evolution regimes on the alternative hosts
and estimating within-population genetic (co)variance for ﬁtness in males and females. Two key predictions were upheld: males
generally experienced stronger selection compared to females and maladaptation increased selection in females. However, mal-
adaptation consistently decreased male-bias in the strength of selection and IaSC was not reduced in maladapted populations.
These ﬁndings imply that sexual selection can be disrupted in stressful environmental conditions, thus reducing one of the potential
beneﬁts of sexual reproduction in maladapted populations.
Adaptation, environmental change, ﬁtness landscape, genetic variance, sexual conﬂict, sexual selection.
Predicting the fate of populations exposed to changing environ-
mental conditions is a major contemporary challenge facing bi-
ologists (Chevin et al. 2010; Hoffmann and Sgr
o 2011; Garcia-
Gonzalez et al. 2012; Walters et al. 2012). Among the many factors
that can contribute to evolutionary rescue, the role of sexual se-
lection is hotly debated (reviewed by: Candolin and Heuschele
2008; Whitlock and Agrawal 2009; Miller and Svensson 2014).
Theory predicts that sexual selection can provide population-
These authors shared first-authorship.
This article corresponds to Vincent, A. M. 2018. Digest: Sexual selection and
conflict in a novel environment. Evolution. https://doi.org/10.1111/evo.13438.
level benefits if it weeds out males of low genetic quality, and
by doing so, removes mutations with generally deleterious ef-
fects from the population (Zahavi 1975; Rowe and Houle 1996;
Lorch et al. 2003; Tomkins and Radwan 2004). Consequently,
sexual selection could increase the rate of adaptation at a low
demographic cost (Manning 1984; Agrawal 2001; Siller 2001),
because females–whose reproductive rate ultimately limits popu-
lation growth–would experience weaker selection and not suffer
the costs of adaptation (sensu Haldane 1957).
Sexual selection is generally expected to be stronger in males
than in females in polygamous species (Bateman 1948; Robert
1972; Clutton-Brock and Parker 1992; Andersson 1994; Arnqvist
2017 The Author(s). Evolution
2017 The Society for the Study of Evolution.
Evolution 72-3: 518–530