Saturday, February 9, 2019

Interplay Between Genetic and Environmental Contributions in the Unfolding of Personality Differences from Early Adolescence to Young Adulthood

Unravelling the Interplay Between Genetic and Environmental Contributions in the Unfolding of Personality Differences from Early Adolescence to Young Adulthood. Christian Kandler et al. European Journal of Personality,

Abstract: In two studies, we examined the genetic and environmental sources of the unfolding of personality trait differences from childhood to emerging adulthood. Using self‐reports from over 3000 representative German twin pairs of three birth cohorts, we could replicate previous findings on the primary role of genetic sources accounting for the unfolding of inter‐individual differences in personality traits and stabilizing trait differences during adolescence. More specifically, the genetic variance increased between early (ages 10–12 years) and late (ages 16–18 years) adolescence and stabilized between late adolescence and young adulthood (ages 21–25 years). This trend could be confirmed in a second three‐wave longitudinal study of adolescents' personality self‐reports and parent ratings from about 1400 Norwegian twin families (average ages between 15 and 20 years). Moreover, the longitudinal study provided evidence for increasing genetic differences being primarily due to accumulation of novel genetic influences instead of an amplification of initial genetic variation. This is in line with cumulative interaction effects between twins' correlated genetic makeups and environmental circumstances shared by adolescent twins reared together. In other words, nature × nurture interactions rather than transactions can account for increases in genetic variance and thus personality variance during adolescence.

Is the Capacity for Vocal Learning in Vertebrates Rooted in Fish Schooling Behavior?

Is the Capacity for Vocal Learning in Vertebrates Rooted in Fish Schooling Behavior? Matz Larsson, Benjamin W. Abbott. Evolutionary Biology, December 2018, Volume 45, Issue 4, pp 359–373.

Abstract: The capacity to learn and reproduce vocal sounds has evolved in phylogenetically distant tetrapod lineages. Vocal learners in all these lineages express similar neural circuitry and genetic factors when perceiving, processing, and reproducing vocalization, suggesting that brain pathways for vocal learning evolved within strong constraints from a common ancestor, potentially fish. We hypothesize that the auditory-motor circuits and genes involved in entrainment have their origins in fish schooling behavior and respiratory-motor coupling. In this acoustic advantages hypothesis, aural costs and benefits played a key role in shaping a wide variety of traits, which could readily be exapted for entrainment and vocal learning, including social grouping, group movement, and respiratory-motor coupling. Specifically, incidental sounds of locomotion and respiration (ISLR) may have reinforced synchronization by communicating important spatial and temporal information between school-members and extending windows of silence to improve situational awareness. This process would be mutually reinforcing. Neurons in the telencephalon, which were initially involved in linking ISLR with forelimbs, could have switched functions to serve vocal machinery (e.g. mouth, beak, tongue, larynx, syrinx). While previous vocal learning hypotheses invoke transmission of neurons from visual tasks (gestures) to the auditory channel, this hypothesis involves the auditory channel from the onset. Acoustic benefits of locomotor-respiratory coordination in fish may have selected for genetic factors and brain circuitry capable of synchronizing respiratory and limb movements, predisposing tetrapod lines to synchronized movement, vocalization, and vocal learning. We discuss how the capacity to entrain is manifest in fish, amphibians, birds, and mammals, and propose predictions to test our acoustic advantages hypothesis.

Monozygotic Twins Seem To Have Higher Genetic Quality (significantly more physically attractive & healthier) than DZ Twins and Singletons; MZ twins may be a quality-maximizing feature of sexual reproduction

Do Monozygotic Twins Have Higher Genetic Quality than Dizygotic Twins and Singletons? Hints from Attractiveness Ratings and Self-Reported Health. Satoshi Kanazawa, Nancy L. Segal. Evolutionary Biology,

Abstract: Evolutionary theories generally concur that sexual reproduction and genetic recombination evolved to maximize genetic variability. Thus, the existence of monozygotic (MZ) twins, which do not take advantage of genetic recombination for each offspring, poses a puzzle. Evolutionary logic of inclusive fitness suggests that parents with high-quality genes may be more likely to produce MZ twins. Analyses of data from the National Longitudinal Study of Adolescent to Adult Health show that MZ twins were significantly more physically attractive and healthier than dizygotic (DZ) twins and singletons. These results suggest that MZ twins may possess higher-quality genes than DZ twins and singletons, and support one of the first evolutionary theories of MZ twinning that specifies its ultimate functions.

Keywords: Twin research Monozygotic twin conception Add Health

Little is known about the operation of male mate choice in systems with perceived high costs to male choosiness, like Rana sylvatica; matings with preferred females produced fewer and lower-quality offspring

Fitness costs of mating with preferred females in a scramble mating system. Lindsey Swierk, Tracy Langkilde. Behavioral Ecology, arz001,

Abstract: Little is known about the operation of male mate choice in systems with perceived high costs to male choosiness. Scramble mating systems are one type of system in which male choice is often considered too costly to be selected. However, in many scramble mating systems, there are also potentially high rewards of male choosiness, as females vary dramatically in reproductive output and males typically mate once per season and/or per lifetime. Using scramble mating wood frogs (Rana sylvatica), we tested whether males gain fitness benefits by mating with preferred females. We conducted choice trials (1 male presented simultaneously with 2 females) and permitted males to mate with their preferred or nonpreferred female. Offspring of preferred and nonpreferred females were reared in the laboratory and field, and we quantified various fitness-relevant parameters, including survivorship and growth rates. Across multiple parameters measured, matings with preferred females produced fewer and lower-quality offspring than did those with nonpreferred females. Our results are inconsistent with the idea that mate choice confers benefits on the choosing sex. We instead propose that, in scramble systems, males will be more likely to amplex females that are easier to capture, which may correlate with lower quality but increases male likelihood of successfully mating. Such male choice may not favor increased fitness when the operational sex ratio is less biased toward males in scramble mating systems but is, instead, a bet-hedging tactic benefitting males when available females are limited.

Our data suggest that an untested parameter of male wood frog mate choice may also play a role in determining its rela-tive costs and benefits. In recent decades, mate choice based on genetic compatibility has been demonstrated to be an important and widely observed component of mate choice (see Brown 1997; Tregenza and Wedell 2000; Mays and Hill 2004). In particular, mate choice based on dissimilarity of major histocompatibility complex (MHC) genes has been observed in humans (Wedekind et al. 1995) and other species (e.g., Gowaty et al. 2003; Agbali et al. 2010; Rymešová et al. 2017; for review see Kamiya et al. 2014); benefits of choosing a mate with dissimilar MHC genes include provisioning offspring with a greater variety of cell-surface proteins that enable the immune system to identify and fight pathogens and parasites (Bernatchez and Landry 2003; Piertney and Oliver 2006; Ruff et al. 2012). If male mate choice in wood frogs also has an MHC-compatibility component (or similar), then it could be pre-dicted that, when faced with challenges to the immune system, offspring of preferred females would have a fitness advantage over the offspring of nonpreferred females. When taken as a whole, our data support this idea. In the lab, in the absence of immune chal-lenges, offspring of preferred females had lower survivorship than the offspring of nonpreferred females (Figure 3a), possibly due to reasons associated with female catchability, as proposed above. However, in the presence of numerous immune challenges in the field, this difference in offspring survivorship disappears (Figure 4a). A MHC-related fitness cost to mating with nonpreferred mates could be responsible for closing the gap between preferred and nonpreferred offspring field survivorship. While admittedly far from conclusive, these results imply that multiple types of mate choice may exist in this scramble system and could warrant future study.