In the natural world, the presence of multiple male types within a single species has long posed a perplexing evolutionary puzzle. Conventional wisdom rooted in Darwinian theory might predict the dominance of a singular “best” male phenotype, refined through natural selection over millions of years. Yet, reality frequently contradicts this notion as diverse male morphs coexist and thrive in many animal populations. Recently, a collaborative research effort led by scientists from the Julius-Maximilians-Universität Würzburg (JMU), alongside partners from the German Cancer Research Centre (DKFZ) and the University of Halle-Wittenberg, has illuminated an elegant mechanism behind this phenomenon: mate copying. Their findings, published in the prestigious Proceedings of the National Academy of Sciences, explore how social learning and information flow shape phenotypic polymorphism in nature.
Traditional evolutionary biology often portrays mate choice as a predominantly individualistic process, guided by private information such as sensory perception, experiential learning, or genetic programming. According to Professor Chaitanya Gokhale, head of Theoretical Evolutionary Biology at JMU, this paradigm posits that each individual independently evaluates the genetic quality of prospective mates and selects the optimal partner to maximize offspring fitness. However, the new empirical evidence and mathematical modeling presented challenge this assumption decisively. The research reveals a sophisticated layer of social interaction—where animals observe the choices made by their conspecifics and mirror these behaviors—a process termed “mate copying.”
Mate copying introduces an intriguing dynamic where individual mating decisions are no longer insulated but instead interwoven within a web of collective behavior. To conceptualize this, Govhale provides an everyday analogy — choosing a restaurant not by inspecting the menu in detail but by opting for the establishment bustling with patrons. This shift from private to social information profoundly influences mating outcomes across diverse taxa, including vertebrates like birds and fish, as well as invertebrates such as Drosophila melanogaster, the common fruit fly.
Understanding the evolutionary consequences of mate copying necessitates exploring its impact on population polymorphism—the stable coexistence of multiple phenotypes within a species. Classical mate choice, centered on private assessment, tends to drive phenotypic convergence towards the fittest type, effectively eroding diversity. Conversely, socially influenced mate choice, especially when widespread, transforms the selection landscape. The team developed innovative mathematical models extending beyond previous binary frameworks, accommodating numerous morphs to reflect ecological complexity realistically. This flexible modeling approach enables simulation of evolutionary dynamics across multifaceted mating systems.
One particularly compelling insight from these models is the identification of two distinct strategies underpinning mate copying: conformity and anti-conformity. Conformity involves the majority adopting the prevalent mating preference, thereby reinforcing dominance of common morphs. Paradoxically, this collective tendency amplifies the fixation of biologically inferior traits due to social momentum, impeding the establishment of rarer, genetically superior morphs. On the other hand, anti-conformity—where individuals deliberately favor less common male types—functions as a stabilizing force, preserving phenotypic diversity within populations over extended evolutionary timescales.
Integral to these dynamics is the concept of a “critical copying probability,” a threshold quantifying the proportion of a population that must engage in mate copying to override natural selection. The Würzburg-led team’s empirical data and computational analysis suggest a pivotal value near 38% in systems with three distinct morphs. Beyond this tipping point, social influence gains the upper hand, enabling even phenotypically suboptimal morphs to dominate the gene pool. Such thresholds provide a quantitative framework to predict when social learning mechanisms will shape rather than simply reflect evolutionary trajectories.
Further enriching their exploration, the research articulates how the plasticity of copying behavior itself modulates population outcomes. When females incur costs by selecting a common but suboptimal male morph, there exists a feedback loop that reduces their propensity to copy. This diminishing copying probability acts as a dynamic balancing mechanism, ensuring neither social conformity nor natural selection singularly dictate the evolutionary fate of traits. This nuanced interplay sustains phenotypic polymorphism, offering an evolutionary explanation for previously enigmatic biological observations.
The research also provides a long-awaited resolution to the “lek paradox,” a long-standing evolutionary conundrum arising in mating systems where males aggregate to display traits conspicuously to females. Classical theory expects intense sexual selection pressures in such systems to homogenize male phenotypes. Contrarily, empirical evidence consistently shows remarkable variability among males on leks. The integrative mathematical model now reveals that the combined effects of private mate preference and socially mediated mate copying—be it conformist or anti-conformist—can maintain trait diversity in lekking species, reconciling theory with observed biodiversity.
Beyond theoretical significance, these findings harbor urgent implications for conservation biology and species management programs. The ability to predict how social dynamics influence phenotypic diversity equips conservationists with tools to evaluate risks to endangered populations. Social learning might accelerate the spread of advantageous adaptations essential for survival, or conversely, propagate maladaptive trends that imperil genetic resilience. Understanding these processes is vital for crafting interventions that sustain evolutionary potential amid environmental change.
Notably, this research underscores a profound conceptual shift in evolutionary thought: genes do not operate in isolation, but their expression and fitness effects are modulated by socially transmitted information and behavioral ecology. By integrating mathematical models with empirical data, this study bridges the divide between abstract theoretical predictions and complex natural realities. It elevates our comprehension of evolution as a multifaceted process shaped not only by genetic inheritance but also by information flow within biological communities.
Ultimately, the Würzburg team’s groundbreaking work highlights how mate copying, as a form of social learning, can sculpt population diversity in ways classical evolution could not explain. Their advanced modeling frameworks open new avenues for investigating the role of behavior in shaping evolutionary outcomes and exemplify the power of interdisciplinary research in illuminating the intricacies of life’s diversity.
Subject of Research: Animals
Article Title: Phenotypic polymorphism via mate copying
News Publication Date: 23-Feb-2026
Web References: http://dx.doi.org/10.1073/pnas.2510849123
