The Evolution of Competition

Human competition is, at least partially, responsible for some of the transcended achievements of the species (walking on the moon, the polio vaccine, etc.), but the forces unleashed by competition have also led to profound human suffering (warfare, domination of one group by another group, etc.). In this article, the authors approach competition from an evolutionary perspective, applying Darwin’s theories of natural and sexual selection to understand better the nature of human competition. From the perspective of evolutionary psychology, humans engage in competition to gain resources, including status, food, and mating opportunities. Males tend to engage in more overt and aggressive forms of competition than females, but both sexes desire access to material and cultural goods associated with reproductive fitness. In the last roughly seventy years, the nature of men’s competition has transformed dramatically leading to declines in both within and between-group violence. As developed societies have succeeded in suppressing more overt and destructive forms of male–male competition, men attempt to gain status through occupational success, cognitive sophistication, moral signaling, and other relatively nonviolent behaviors. In this sense, men’s and women’s competition is more similar than it was a century ago. However, women’s competition is still less visible and relies on more indirect mechanisms (e.g., spreading gossip, subtle use of body language). For this reason, female–female competition has attracted less study than male–male competition. Fortunately, in the last decade, psychologists have partially redressed this imbalance.

Sztuka jako adaptacja: uniwersalizm w estetyce ewolucyjnej

The paper is a synoptic review of my monograph Art as an adaptation. Universalism in evolutionary aesthetics (2018), which is the analysis of the evolutionary theory of art — a theoretical phenomenon that has been developed in recent years, a discipline that explains the origin of human admiration for beauty and human inclination to create and admire art based on Darwinian theories of natural and sexual selection. The main objective of the paper is to determine to what extent the evolutionary perspective enriches our concept of art and whether naturalization and universalization of the analysis of art can be enlivening for aesthetics in the face of its crisis. On a more general level, the aim of the work is to demonstrate that the use of evolutionary hypotheses in the humanities, based on the achievements of, among others, biology and evolutionary psychology, human behavioural ecology and cognitive archaeology, can become a recipe for the conceptual and identity impasse in the humanities in general. In the paper I make a case for the claim that the evolutionary study of art and artistic behaviour indicates art’s inalienability “as a result of the inner human need”. It also formulates justified assumptions in a philosophical debate on the existence of aesthetic universals and the credibility of the universalist position in art theory. According to this, art operates as part of a natural, immutable apparatus of sensations, universal to all humans.

The Alignment of Natural and Sexual Selection

Sexual selection has the potential to decrease mean fitness in a population through an array of costs to nonsexual fitness. These costs may be offset when sexual selection favors individuals with high nonsexual fitness, causing the alignment of sexual and natural selection. We review the many laboratory experiments that have manipulated mating systems aimed at quantifying the net effects of sexual selection on mean fitness. These must be interpreted in light of population history and the diversity of ways manipulations have altered sexual interactions, sexual conflict, and sexual and natural selection. Theory and data suggest a net benefit is more likely when sexually concordant genetic variation is enhanced and that ecological context can mediate the relative importance of these different effects. Comparative studies have independently examined the consequences of sexual selection for population/species persistence. These provide little indication of a benefit, and interpreting these higher-level responses is challenging. Expected final online publication date for the Annual Review of Ecology, Evolution, and Systematics, Volume 52 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

First records of a new color pattern in the Goldblotch Grouper, Epinephelus costae (Steindachner, 1878) (Actinopterygii: Serranidae) and first record of leucism in the European conger, Conger conger (Linnaeus, 1758) (Actinopterygii: Congridae)

In many fish, color patterns are striking features and can play an important role in both natural and sexual selection. Furthermore, details of color patterns are in some cases valid tools for species identification. However, fish can also show some genetic abnormalities, such as albinism and leucism. In this research, we report for the first time a new color pattern for Epinephelus costae (Steindachner, 1878), for which it is known an ontogenetic shift in color pattern, and the first case of leucism in Conger conger (Linnaeus, 1758).

Colour variation of the Maltese wall lizards (Podarcis filfolensis) at population and individual levels in the Linosa island

The research on animal colouration has always been of great interest for biologists but since the last decades it has grown exponentially thanks to multidisciplinary approaches. Animals have found several ways to deal with the camouflage/communication trade-off in colouration, leading to the evolution of alternative patterns of variation of colourations at different levels including signal partitioning and spatial resolution of colouration. In this paper we analyse the variability of dorsal and ventral colouration in males and females of Maltese wall lizards in three populations on Linosa. We collected high-resolution digital images of dorsal, ventral and throat colouration from 61 lizards (32 males and 29 females). We showed that the colouration differs among sexes and body regions within the same individual. Colourations are also variable among individuals within population, as well as among different populations across the Island. Finally, we detected a lizard’s colouration shifts with increasing body size. Those result supports the hypothesis that colouration in this species evolved under the competing pressures of natural and sexual selection to promote signals that are visible to conspecifics while being less perceptible to avian predators. Graphic abstract

Integrating natural and sexual selection across the biphasic life cycle

An alternation between diploid and haploid phases is universal among sexual eukaryotes. Across this biphasic cycle, natural selection and sexual selection occur in both phases. Together, these four stages of selection act on the phenotypes of individuals and influence the evolutionary trajectories of populations, but are rarely studied holistically. Here, we provide a conceptual framework that transcends taxonomic groups, and unifies the entire selection landscape within and across the diploid and haploid phases. Our synthesis produces six direct links among four selection stages, and from this we define four types of parental effect. We argue that knowledge of the complex and intertwined opportunities for selection within biphasic life cycles will offer clearer insights into key ecological and evolutionary processes, with benefits to applied science.

The mating system affects the temperature sensitivity of male and female fertility

1. To mitigate effects of climate change it is important to understand species responses to increasing temperatures. This has often been done by studying survival or activity at temperature extremes. Before such extremes are reached, however, effects on fertility may already be apparent. 2. Sex differences in the thermal sensitivity of fertility (TSF) could impact species persistence under climate warming because female fertility is typically more limiting to population growth than male fertility. However, little is known about sex differences in TSF. 3. Here we first demonstrate that the mating system can strongly influence TSF using the seed beetle Callosobruchus maculatus. We exposed populations carrying artificially induced mutations to two generations of short-term experimental evolution under alternative mating systems, manipulating the opportunity for natural and sexual selection on the mutations. We then measured TSF in males and females subjected to juvenile or adult heat stress. 4. Populations kept under natural and sexual selection had higher fitness, but similar TSF, compared to control populations kept under relaxed selection. However, females had higher TSF than males, and strikingly, this sex difference had increased over only two generations in populations evolving under sexual selection. 5. We hypothesized that an increase in male-induced harm to females during mating had played a central role in driving this evolved sex difference, and indeed, remating under conditions limiting male harassment of females reduced both male and female TSF. Moreover, we show that manipulation of mating system parameters in C. maculatus generates intraspecific variation in the sex difference in TSF equal to that found among a diverse set of studies on insects. 6. Our study provides a causal link between the mating system and TSF. Sexual conflict, (re)mating rates, and genetic responses to sexual selection differ among ecological settings, mating systems and species. Our study therefore also provides mechanistic understanding for the variability in previously reported TSFs which can inform future experimental assays and predictions of species responses to climate warming.

Responses of intended and unintended receivers to a novel sexual signal suggest clandestine communication

Inadvertent cues can be refined into signals through coevolution between signalers and receivers, yet the earliest steps in this process remain elusive. In Hawaiian populations of the Pacific field cricket, a new morph producing a novel and incredibly variable song (purring) has spread across islands. Here we characterize the current sexual and natural selection landscape acting on the novel signal by (1) determining fitness advantages of purring through attraction to mates and protection from a prominent deadly natural enemy, and (2) testing alternative hypotheses about the strength and form of selection acting on the novel signal. In field studies, female crickets respond positively to purrs, but eavesdropping parasitoid flies do not, suggesting purring may allow private communication among crickets. Contrary to the sensory bias and preference for novelty hypotheses, preference functions (selective pressure) are nearly flat, driven by extreme inter-individual variation in function shape. Our study offers a rare empirical test of the roles of natural and sexual selection in the earliest stages of signal evolution.

Extensive hybridization reveals multiple coloration genes underlying a complex plumage phenotype

Coloration is an important target of both natural and sexual selection. Discovering the genetic basis of colour differences can help us to understand how this visually striking phenotype evolves. Hybridizing taxa with both clear colour differences and shallow genomic divergences are unusually tractable for associating coloration phenotypes with their causal genotypes. Here, we leverage the extensive admixture between two common North American woodpeckers—yellow-shafted and red-shafted flickers—to identify the genomic bases of six distinct plumage patches involving both melanin and carotenoid pigments. Comparisons between flickers across approximately 7.25 million genome-wide SNPs show that these two forms differ at only a small proportion of the genome (mean F ST = 0.008). Within the few highly differentiated genomic regions, we identify 368 SNPs significantly associated with four of the six plumage patches. These SNPs are linked to multiple genes known to be involved in melanin and carotenoid pigmentation. For example, a gene ( CYP2J19 ) known to cause yellow to red colour transitions in other birds is strongly associated with the yellow versus red differences in the wing and tail feathers of these flickers. Additionally, our analyses suggest novel links between known melanin genes and carotenoid coloration. Our finding of patch-specific control of plumage coloration adds to the growing body of literature suggesting colour diversity in animals could be created through selection acting on novel combinations of coloration genes.