Can interspecies affairs in the dark lead to evolutionary innovation?

Evolutionary adaptation is the adjustment of species to a new or changing environment. Engaging in mutualistic microbial symbioses has been put forward as a key trait that promotes the differential, evolutionary success of many animal and plant lineages (McFall‐Ngai, 2008). Microbial mutualists allow these organisms to occupy new ecological niches where they could not have persisted on their own or would have been constrained by competitors. Vertical transmission of beneficial microbial symbionts from parents to the offspring is expected to link the adaptive association between a given host and microbe, and it can lead to coevolution and sometimes even cospeciation (Fisher, Henry, Cornwallis, Kiers, & West, 2017). Vertical transmission also causes bottlenecks that strongly reduce the effective population size and genetic diversity of the symbiont population. Moreover, vertically transmitted symbionts are assumed to have fewer opportunities to exchange genes with relatives in the environment. In a “From the Cover” article in this issue of Molecular Ecology, Breusing, Johnson, Vrijenhoek, and Young (2019) investigated whether hybridization among different host species could lead to interspecies exchange of otherwise strictly vertically transmitted symbionts. Hybridization of divergent lineages can potentially cause intrinsic and extrinsic incompatibilities, swamp rare alleles, and lead to population extinctions. In some cases, however, it might also create novel trait combinations that lead to evolutionary innovation (Marques, Meier, & Seehausen, 2019). Breusing et al. (2019) linked the concept of hybridization to symbiont transmission, and their findings have significant implications for the study of evolution of vertically transmitted symbionts and their hosts.     

Does evolution lead to maximizing behavior?

A long‐standing question in biology and economics is whether individual organisms evolve to behave as if they were striving to maximize some goal function. We here formalize this “as if” question in a patch‐structured population in which individuals obtain material payoffs from (perhaps very complex multimove) social interactions. These material payoffs determine personal fitness and, ultimately, invasion fitness. We ask whether individuals in uninvadable population states will appear to be maximizing conventional goal functions (with population‐structure coefficients exogenous to the individual's behavior), when what is really being maximized is invasion fitness at the genetic level. We reach two broad conclusions. First, no simple and general individual‐centered goal function emerges from the analysis. This stems from the fact that invasion fitness is a gene‐centered multigenerational measure of evolutionary success. Second, when selection is weak, all multigenerational effects of selection can be summarized in a neutral type‐distribution quantifying identity‐by‐descent between individuals within patches. Individuals then behave as if they were striving to maximize a weighted sum of material payoffs (own and others). At an uninvadable state it is as if individuals would freely choose their actions and play a Nash equilibrium of a game with a goal function that combines self‐interest (own material payoff), group interest (group material payoff if everyone does the same), and local rivalry (material payoff differences).     

Does male-biased predation lead to male scarcity in viviparous fish?

Male predation risk due to ornaments seldom reduces female mating opportunities because males escape costs through alternative mating strategies and/or females cease to select for highly ornamented males. Males of the Amarillo fish Girardinichthys multiradiatus (Goodeidae) have large sexually selected fins that impair attack-avoidance manoeuvres. This fish was used to seek evidence that intersexual selection for handicapping traits can result in a deficit of acceptable mating partners. Also it was examined whether, under male scarcity, females remain choosy to the point of missing mating opportunities, and that they can exert effective control over matings, which is a pre-condition of effective female choice. It was found that snakes prey disproportionately on males, that it leads to female-biased sex ratios, and that highly ornamented males are more scarce after predation than males with small ornaments. Females can avoid being fertilized by unattractive males, and that missing one reproductive period can lead to infertility. Thus it appears that females have promoted the exaggeration of a male trait that increases predation risk, remain choosy even when acceptable males are scarce, and pay a large cost when missing mating opportunities. A prediction from these results is that females enjoy substantial fitness benefits from mating with highly ornamented males, which override the occasional fatal costs of refusing to mate with sub–optimal males. One potential consequence of female selectivity and control over matings when males are scarce may be a reduced capability to colonize new habitats.     

Does respiratory sinus arrhythmia occur in fishes?

The hypothesis that respiratory modulation of heart rate variability (HRV) or respiratory sinus arrhythmia (RSA) is restricted to mammals was tested on four Antarctic and four sub-Antarctic species of fish, that shared close genotypic or ecotypic similarities but, due to their different environmental temperatures, faced vastly different selection pressures related to oxygen supply. The intrinsic heart rate (fH) for all the fish species studied was approximately 25% greater than respiration rate (fV), but vagal activity successively delayed heart beats, producing a resting fH that was synchronized with fV in a progressive manner. Power spectral statistics showed that these episodes of relative bradycardia occurred in a cyclical manner every 2-4 heart beats in temperate species but at >4 heart beats in Antarctic species, indicating a more relaxed selection pressure for cardio-respiratory coupling. This evidence that vagally mediated control of fH operates around the ventilatory cycle in fish demonstrates that influences similar to those controlling RSA in mammals operate in non-mammalian vertebrates.     

Does long-term experimental antiorthostasis lead to cardiovascular deconditioning in the rat?

Microgravity or simulated microgravity induces acute and chronic cardiovascular responses, whose mechanism is pivotal for understanding of physiological adaptation and pathophysiological consequences. We investigated hemodynamic responses of conscious Wistar rats to 45? head-down tilt (HDT) for 7 days. Arterial blood pressure (BP) was recorded by telemetry. Heart rate (HR), spectral properties and the spontaneous baroreflex sensitivity (sBRS) were calculated. Head-up tilt (HUT) was applied for 2 h before and after HDT to assess the degree of any possible cardiovascular deconditioning. Horizontal control BP and HR were 112.5+/-2.8 mmHg and 344.7+/-10 bpm, respectively. HDT elicited an elevation in BP and HR by 8.3 % and 8.8 %, respectively, in less than 1 h. These elevations in BP and HR were maintained for 2 and 3 days, respectively, and then normalized. Heart rate variability was unchanged, while sBRS was permanently reduced from the beginning of HDT (1.01+/-0.08 vs. 0.74+/-0.05 ms/mmHg). HUT tests before and after HDT resulted in BP elevations (6.9 vs. 11.6 %) and sBRS reduction (0.44 vs. 0.37 ms/mmHg), respectively. The pressor response during the post-HDT HUT test was accompanied by tachycardia (13.7 %). In conclusion, chronic HDT does not lead to symptoms of cardiovascular deconditioning. However the depressed sBRS and tachycardic response seen during the post-HDT HUT test may indicate disturbances in cardiovascular control.     

Environmental signaling and evolutionary change: can exposure of pregnant mammals to environmental estrogens lead to epigenetically induced evolutionary changes in embryos?

DNA methylation is one of the epigenetic and hereditary mechanisms regulating genetic expression in mammalian cells. In this review, we propose how certain natural agents, through their dietary consumption, could induce changes in physiological aspects in mammalian mothers, leading to alterations in DNA methylation patterns of the developing fetus and to the emergence of new phenotypes and evolutionary change. Nevertheless, we hypothesize that this process would require (i) certain key periods in the ontogeny of the organism where the environmental stimuli could produce effects, (ii) particular environmental agents as such stimuli, and (iii) that a genomic persistent change be consequently produced in a population. Depending on the persistence of the environmental stimuli and on whether the affected genes are imprinted genes, induced changes in DNA methylation patterns could become persistent. Moreover, some fragments could be more frequently methylated than others over several generations, leading to biased base change and evolutionary consequences.     

Does leaf ontogeny lead to changes in defensive strategies against insect herbivores?

Plants use different defense strategies throughout their ontogenetic development. In this study, three questions were proposed: (1) Is there a greater abundance of ants on young leaves, which possess active extrafloral nectaries, than on mature leaves? (2) Do ants exert an indirect defense that is effective against the attack of herbivorous insects? (3) Do mature leaves have a greater concentration of physical and chemical defense than young leaves? These questions were addressed through an ant-exclusion experiment in which two branches of Copaifera langsdorffii (n = 25) were marked and monitored throughout the entire foliar expansion and development period. A reduction in the abundance of ants throughout foliar development was observed. The ants exerted an effective defense against herbivores on C. langsdorffii: the branches where ants were excluded had a greater number of herbivores. The mature leaves possessed a greater index of leaf sclerophylly than young leaves, but the leaves did not differ in the concentration of tannins. The foliar ontogeny of C. langsdorffii promoted an inversion in the defense strategy against herbivores, and despite showing an opportunistic relationship, the interaction between ants and extrafloral nectaries appears to play an important role in structuring the interactions between herbivorous insects and their host plants.     

How important is it to consider lineage diversification heterogeneity in macroevolutionary studies? Lessons from the lizard family Liolaemidae

Macroevolutionary and biogeographical studies commonly apply multiple models to test state-dependent diversification. These models track the association between states of interest along a phylogeny, although many of them do not consider whether different clades might be evolving under different evolutionary drivers. Yet, they are still commonly applied to empirical studies without careful consideration of possible lineage diversification heterogeneity along the phylogenetic tree. A recent biogeographic study has suggested that orogenic uplift of the southern Andes has acted as a species pump, driving diversification of the lizard family Liolaemidae (307 described species), native to temperate southern South America. Here, we argue against the Andean uplift as main driver of evolution in this group. We show that there is a clear pattern of heterogeneous diversification in the Liolaemidae, which biases state- and environment-dependent analyses in, respectively, the GeoSSE and RPANDA programs. We show here that there are two shifts to accelerated speciation rates involving two clades that have both been classified as having “Andean” distributions. We incorporated the Geographic Hidden-State Speciation and Extinction model (GeoHiSSE) to accommodate unrelated diversification shifts, and also re-analyzed the data in RPANDA program after splitting biologically distinct clades for separate analyses, as well as including a more appropriate set of models. We demonstrate that the “Andean uplift” hypothesis is not supported when the heterogeneous diversification histories among these lizards is considered. We use the Liolaemidae as an ideal system to demonstrate potential risks of ignoring clade-specific differences in diversification patterns in macroevolutionary studies. We also implemented simulations to show that, in agreement with previous findings, the HiSSE approach can effectively and substantially reduce the level of distribution-dependent models receiving the highest AIC weights in such scenarios. However, we still find a relatively high rate (15%) of distribution-dependent models receiving the highest AIC weights, and provide recommendations related to the set of models included in the analyses that reduce these rates by half. Finally, we demonstrate that trees including clades following different dependent-drivers affect RPANDA analyses by producing different outcomes, ranging from partially correct models to completely misleading results. We provide recommendations for the implementation of both programs.     

Does diet in Celtic Sea fishes reflect prey availability?

Feeding preferences of Celtic Sea fishes were investigated using a database of stomach content records, collected between 1977 and 1994. The diet of cod Gadus morhua , hake Merluccius merluccius , megrim Lepidorhombus whiffiagonis , whiting Merlangius merlangus and saithe Pollachius virens changed markedly as the animals grew larger, and although large predators generally chose larger bodied prey, the variability of prey sizes consumed also increased. Large predators continued to select small, low value, benthic prey ( e.g . Callionymus spp. and Trisopterus spp.) which were easier to catch, rather than larger, more energy lucrative pelagic prey ( e.g . mackerel Scomber scombrus ), even though these pelagic prey‐fishes were nearly always available and were often very abundant. Stock estimates of the International Council for the Exploration of the Sea and U.K. groundfish survey catches were used as indices of prey abundance. Blue‐whiting Micromesistius poutassou and other small pelagic fishes ( Argentina spp. and clupeoids) were identified as being particularly important, and were consumed by some predators more often than would be expected given the abundance of these prey in the environment. There was no evidence for density‐dependent feeding by predators on mackerel and only hake exhibited density‐dependent feeding on horse‐mackerel. Hake, cod and megrim consumed more blue‐whiting when this prey was at higher abundance in the environment. In choosing what prey to consume, predators must balance costs and benefits, considering the quality of prey and the energy expended during search, capture and handling.     

Does consanguinity lead to decreased incidence of breast cancer?

Background: In the Middle East region, consanguinity remains to be a central feature where it has shown an increasing trend. Breast cancer is an extremely complex disease, characterized by a progressive multistep process caused by interactions of both environmental and genetic factors. Aim: The aim of this study was to examine the possible effect of consanguinity on the risk of breast cancer in a population with a high rate of consanguinity and find the associated risk-modifying factors. Subjects and methods: The study included 167 Qatari and other Arab expatriates women with breast cancer and 341 age and ethnicity matched control women. A questionnaire that included the socio-demographic information, type of consanguinity, medical history, life style habits, dietary intake and tumor grade was designed to collect, the information of cases and controls. A total number of 214 breast cancer patients were approached and 167 cases completed the questionnaires with a response rate of 78%. Of the 417 healthy women who agreed to participate in this study, 341 responded to the questionnaire (81.8%). Results: The study revealed that the rate of parental consanguinity was lower in breast cancer patients (24%) than in controls (32.3%) (p = 0.062). Female controls were slightly younger (46.5 ± 11.9) than breast cancer patients (48.4 ± 10.7). Breast cancer incidence was significantly higher in Qatari women (34.1%) compared to other Arab women (65.9%) (p = 0.034). A significant difference was noted only in occupation of the studied women between cases and controls (p < 0.001). Overweight (46.7%) and obesity (32.9%) were significantly higher in female breast cancer patients compared to controls (p = 0.028). Overall, the mean coefficient of consanguinity was lower in breast cancer patients (0.014) than in controls (0.018) (p = 0.0125). Family history of breast cancer was significantly more often in breast cancer patients (14.4%) than in controls (6.2%) (p = 0.002). However, the family history of breast cancer was more often positive in cases of non-consanguineous parents (15.7%) than cases of consanguineous parents (10.0%). Conclusion: The present study revealed the lack of association between of breast cancer and the parental consanguinity in Arab women residing in Qatar. The family history of breast cancer and the body mass index (BMI) are highly associated with breast cancer.     

Does resource availability help determine the evolutionary route to multicellularity?

Genetic heterogeneity and homogeneity are associated with distinct sets of adaptive advantages and bottlenecks, both in developmental biology and population genetics. Whereas populations of individuals are usually genetically heterogeneous, most multicellular metazoans are genetically homogeneous. Observing that resource scarcity fuels genetic heterogeneity in populations, we propose that monoclonal development is compatible with the resource‐rich and stable internal environments that complex multicellular bodies offer. In turn, polyclonal development persists in tumors and in certain metazoans, both exhibiting a closer dependence on external resources. This eco‐evo‐devo approach also suggests that multicellularity may originally have emerged through polyclonal development in early metazoans, because of their reduced shielding from environmental fluctuations.     

Does quasi-local competition lead to pattern formation in metapopulations? An explicit resource competition model

In metapopulations, competitive interactions may extend beyond the confines of the local population such that members of neighbouring habitat patches affect each other adversely (quasi-local competition). We derive a model for quasi-local competition from first principles, assuming that individuals compete for shared resources and members of a population spend a certain fraction of their foraging time in the adjacent populations. Contrary to the results of Doebeli and Killingback [2003. Theor. Popul. Biol. 64, 397-416], our model does not produce spatial patterns of population densities in homogeneous environments. Quasi-local competition nevertheless contributes to pattern formation by amplifying the effect of heterogeneities in the external environment, and this amplification can be extremely strong when dispersal is absent. We discuss why apparently similar models lead to contrasting results.     

Does access to fast food lead to super-sized pregnant women and whopper babies?

Rise in the availability of fast-food restaurants has been blamed, at least partly, for the increasing obesity in the U.S. The existing studies of obesity have focused primarily on children, adolescents, and adults, and this paper extends the literature by raising a little-studied question and using nationally representative data to answer it. It examines the relationship between the supply of fast-food restaurants and weight gain of pregnant women and their newborns. I study prenatal weight gain because excessive weight gain has been linked to postpartum overweight/obesity and I study both tails of the birthweight distribution because the origin of obesity may be traced to the prenatal period and both tail outcomes have been associated with obesity later in life. I merge the 1998 and 2004 Natality Detail Files with the Area Resource File, and County Business Patterns, which provide data on the number of fast-food restaurants in the metropolitan area where the mother resides. The empirical model includes an extensive list of MSA characteristics and MSA fixed effects to control for factors that may be correlated with both health outcomes and restaurants’ location decision. Results reveal that the fast-food and weight gain relationship is robust to the inclusion of these controls but these controls greatly mitigate the fast food–infant health relationship. Greater access to fast-food restaurants is positively related to mothers’ probability of excessive weight gain but it does not share a statistically significant relationship with birthweight. These relationships hold in all the socioeconomic and demographic subgroups studied.     

Does rapid sequence divergence preclude RNA structure conservation in vertebrates?

Accelerated evolution of any portion of the genome is of significant interest, potentially signaling positive selection of phenotypic traits and adaptation. Accelerated evolution remains understudied for structured RNAs, despite the fact that an RNA’s structure is often key to its function. RNA structures are typically characterized by compensatory (structure-preserving) basepair changes that are unexpected given the underlying sequence variation, i.e., they have evolved through negative selection on structure. We address the question of how fast the primary sequence of an RNA can change through evolution while conserving its structure. Specifically, we consider predicted and known structures in vertebrate genomes. After careful control of false discovery rates, we obtain 13 de novo structures (and three known Rfam structures) that we predict to have rapidly evolving sequences—defined as structures where the primary sequences of human and mouse have diverged at least twice as fast (1.5 times for Rfam) as nearby neutrally evolving sequences. Two of the three known structures function in translation inhibition related to infection and immune response. We conclude that rapid sequence divergence does not preclude RNA structure conservation in vertebrates, although these events are relatively rare.     

Does social complexity lead to sex-biased dispersal in polygynous mammals? A test on ground-dwelling sciurids

Mating systems are well known to influence the dispersing sex,but the magnitude of the sex-biased dispersal has not actuallybeen measured, whereas many theoretical predictions have beenmade. In this study, we tested a new prediction about the coevolutionbetween natal dispersal and sociality from a recent evolutionarilystable strategy (ESS) approach. From a comparative approach,we showed that, in agreement with the model, the male-biaseddispersal increases with increasing level of sociality in polygynousground-dwelling sciurids. In addition, the increase in male-biaseddispersal with increasing sociality results from an increasein male dispersal rates, whereas female dispersal rates remainconstant, contrary to what is expected from the ESS model. Althoughthe mating system through the level of polygyny could act asa confounding factor, our results strengthen previous work thatstates that inbreeding avoidance plays a major role in the evolutionof dispersal for the most social mammalian species.     

Synaptic vesicle exocytosis. Does a lingering kiss lead to fusion?

Direct optical measurements of single synaptic vesicles undergoing exocytosis at a synapse reveal rapid and complete transfer of membrane marker from the vesicle to the plasma membrane (; this issue of Neuron). Contact between the two membranes is consistent with free lipid exchange, such as might result from full fusion of the vesicle and plasma membranes.