The coevolutionary dynamics of cryptic female choice

Abstract

In contrast to sexual selection on traits that affect interactions between the sexes before mating, little theoretical research has focused on the coevolution of postmating traits via cryptic female choice (when females bias fertilization toward specific males). We used simulation models to ask (a) whether and, if so, how nondirectional cryptic female choice (female-by-male interactions in fertilization success) causes deviations from models that focus exclusively on male-mediated postmating processes, and (b) how the risk of sperm competition, the strength of cryptic female choice, and tradeoffs between sperm number and sperm traits interact to influence the coevolutionary dynamics between cryptic female choice and sperm traits. We found that incorporating cryptic female choice can result in males investing much less in their ejaculates than predicted by models with sperm competition only. We also found that cryptic female choice resulted in the evolution of genetic correlations between cryptic female choice and sperm traits, even when the strength of cryptic female choice was weak, and the risk of sperm competition was low. This suggests that cryptic female choice may be important even in systems with low multiple mating. These genetic correlations increased with the risk of sperm competition and as the strength of cryptic female choice increased. When the strength of cryptic female choice and risk of sperm competition was high, extreme codivergence of sperm traits and cryptic female choice preference occurred even when the sperm trait traded off with sperm number. We also found that male traits lagged behind the evolution of female traits; this lag decreased with increasing strength of cryptic female choice and risk of sperm competition. Overall, our results suggest that cryptic female choice deserves more attention theoretically and may be driving trait evolution in ways just beginning to be explored.

Paternity bias and cryptic female choice in chickens

“…Nonetheless, females also play a crucial role in sperm competition by selectively fertilizing different males' sperm ( Evans et al, 2003 ; Birkhead, 2010 ; Lüpold et al, 2013 ; Pizzari and Birkhead, 2000 ). This phenomenon, known as cryptic female choice ( CFC ) ( Firman et al, 2017 ; Kustra and Alonzo, 2023 ), has been observed during various stages of the reproductive process, including shortly after mating and during sperm storage and transport. Previous studies in various species, such as feral fowl ( Pizzari and Birkhead, 2000 ), Drosophila ( Pizzari, 2004 ; Snook and Hosken, 2004 ), spider ( Burger, 2010 ; Peretti and Eberhard, 2010 ) and Odonata ( Córdoba-Aguilar, 2006 ), have observed females mechanically dumping sperm from different males during multiple mating's.…”

Coevolution of longevity and female germline maintenance

“…Interestingly, female animals possess the ability to provide maintenance not only of their own germline cells but also of male ejaculates and haploid male DNA, by synthesizing anti-oxidants in the reproductive tract to neutralize mutagenic reactive oxygen species, and by including mRNA and proteins in the oocyte to detect and repair DNA damage in the early zygote [34][35][36]. Additionally, females may also exert cryptic female choice of male sperm that compete for fertilization of eggs inside the female reproductive tract [37,38], which can serve as an additional barrier screening against male gametes of low genetic quality, even among sperm within an ejaculate from a single male [39,40]. This process bears similarity to apoptosis (controlled cell death) of damaged germline cells, which limits the passing on of deleterious mutations to offspring [36,[41][42][43][44].…”

The surprising complexity and diversity of sperm storage structures across Galliformes

“…Sperm are some of the most diverse cells in the animal kingdom (Pitnick et al., 2009 ), and so it stands to reason that the structures that selectively store them might also vary considerably in both structure and function (Cramer et al., 2023 ). Sperm length has been found to correlate negatively with SST number and positively with SST length in passerines (Briskie & Montgomerie, 1993 ), suggesting that the co‐evolutionary dynamics between male and female post‐copulatory sexual selection may be a driving factor in the evolution of sperm morphology (Kustra & Alonzo, 2023 ). Sperm morphology and female sperm storage organ morphology have been shown to correlate in other taxa as well (mainly invertebrates; Higginson et al., 2012 ; Miller & Pitnick, 2002 ).…”