Meta-analytical evidence for frequency-dependent selection across the tree of life.

Explaining the maintenance of genetic variation in fitness-related traits within populations is a fundamental challenge in ecology and evolutionary biology. Frequency-dependent selection (FDS) is one mechanism that can maintain such variation, especially when selection favours rare variants (negative FDS). However, our general knowledge about the occurrence of FDS, its strength and direction remain fragmented, limiting general inferences about this important evolutionary process. We systematically reviewed the published literature on FDS and assembled a database of 747 effect sizes from 101 studies to analyse the occurrence, strength, and direction of FDS, and the factors that could explain heterogeneity in FDS. Using a meta-analysis, we found that overall, FDS is more commonly negative, although not significantly when accounting for phylogeny. An analysis of absolute values of effect sizes, however, revealed the widespread occurrence of modest FDS. However, negative FDS was only significant in laboratory experiments and non-significant in mesocosms and field-based studies. Moreover, negative FDS was stronger in studies measuring fecundity and involving resource competition over studies using other fitness components or focused on other ecological interactions. Our study unveils key general patterns of FDS and points in future promising research directions that can help us understand a long-standing fundamental problem in evolutionary biology and its consequences for demography and ecological dynamics.

Interactions between fitness components across the life cycle constrain competitor coexistence.

Numerous mechanisms can promote competitor coexistence. Yet, these mechanisms are often considered in isolation from one another. Consequently, whether multiple mechanisms shaping coexistence combine to promote or constrain species coexistence remains an open question. Here, we aim to understand how multiple mechanisms interact within and between life stages to determine frequency-dependent population growth, which has a key role stabilizing local competitor coexistence. We conducted field experiments in three lakes manipulating relative frequencies of two Enallagma damselfly species to evaluate demographic contributions of three mechanisms affecting different fitness components across the life cycle: the effect of resource competition on individual growth rate, predation shaping mortality rates, and mating harassment determining fecundity. We then used a demographic model that incorporates carry-over effects between life stages to decompose the relative effect of each fitness component generating frequency-dependent population growth. This decomposition showed that fitness components combined to increase population growth rates for one species when rare, but they combined to decrease population growth rates for the other species when rare, leading to predicted exclusion in most lakes. Because interactions between fitness components within and between life stages vary among populations, these results show that local coexistence is population specific. Moreover, we show that multiple mechanisms do not necessarily increase competitor coexistence, as they can also combine to yield exclusion. Identifying coexistence mechanisms in other systems will require greater focus on determining contributions of different fitness components across the life cycle shaping competitor coexistence in a way that captures the potential for population-level variation.

Selection on phenotypic plasticity favors thermal canalization.

Climate change affects organisms worldwide with profound ecological and evolutionary consequences, often increasing population extinction risk. Climatic factors can increase the strength, variability, or direction of natural selection on phenotypic traits, potentially driving adaptive evolution. Phenotypic plasticity in relation to temperature can allow organisms to maintain fitness in response to increasing temperatures, thereby "buying time" for subsequent genetic adaptation and promoting evolutionary rescue. Although many studies have shown that organisms respond plastically to increasing temperatures, it is unclear if such thermal plasticity is adaptive. Moreover, we know little about how natural and sexual selection operate on thermal reaction norms, reflecting such plasticity. Here, we investigate how natural and sexual selection shape phenotypic plasticity in two congeneric and phenotypically similar sympatric insect species. We show that the thermal optima for longevity and mating success differ, suggesting temperature-dependent trade-offs between survival and reproduction in both sexes. Males in these species have similar thermal reaction norm slopes but have diverged in baseline body temperature (intercepts), being higher for the more northern species. Natural selection favored reduced thermal reaction norm slopes at high ambient temperatures, suggesting that the current level of thermal plasticity is maladaptive in the context of anthropogenic climate change and that selection now promotes thermal canalization and robustness. Our results show that ectothermic animals also at high latitudes can suffer from overheating and challenge the common view of phenotypic plasticity as being beneficial in harsh and novel environments.

Environmental Conditions during Development Affect Sexual Selection through Trait-Fitness Relationships.

AbstractSexual selection can be shaped by spatial variation in environmental features among populations. Differences in sexual selection among populations generated through the effects of the environment could be shaped via four paths: differences in mean absolute fitness, differences in the means or variances of phenotypes, or differences in the absolute fitness-trait function relationship. Because sexual selection occurs only during the adult life stage, most studies have focused on identifying environmental features that influence these metrics of fitness and trait distributions among adults. However, these adult features could also be affected by environmental factors experienced in early life stages that then shape the trajectory for sexual selection during the adult life stage. Here we investigated how among-population variation in environmental conditions during the juvenile (larval) stage of two species of Enallagma damselflies shapes sexual selection on male body size. We found that environmental factors related to predation pressures, lake primary productivity, and habitat availability play a role in shaping spatial variation in sexual selection. This acts mainly through how the environment affects absolute fitness-body size associations, not spatial variation in mean fitness or body size means and variances. These results demonstrate that the underpinnings of sexual selection in the wild can arise from environmental conditions during prereproductive life stages.

Male-Male Competition Causes Parasite-Mediated Sexual Selection for Local Adaptation.

AbstractSexual selection has been suggested to accelerate local adaptation and promote evolutionary rescue through several ecological and genetic mechanisms. Condition-dependent sexual selection has mainly been studied in laboratory settings, while data from natural populations are lacking. One ecological factor that can cause condition-dependent sexual selection is parasitism. Here, we quantified ectoparasite load (Arrenurus water mites) in a natural population of the common bluetail damselfly (Ischnura elegans) over 15 years. We quantified the strength of sexual selection against parasite load in both sexes and experimentally investigated the mechanisms behind such selection. Then we investigated how parasite resistance and tolerance changed over time to understand how they might influence population density. Parasites reduced mating success in both sexes, and sexual selection was stronger in males than in females. Experiments show that male-male competition is a strong force causing precopulatory sexual selection against parasite load. Although parasite resistance and male parasite tolerance increased over time, suggestive of increasing local adaptation against parasites, no signal of evolutionary rescue could be found. We suggest that condition-dependent sexual selection facilitates local adaptation against parasites and discuss its effects in evolutionary rescue.

Frequency Dependence and Ecological Drift Shape Coexistence of Species with Similar Niches.

The coexistence of ecologically similar species might be counteracted by ecological drift and demographic stochasticity, both of which erode local diversity. With niche differentiation, species can be maintained through performance trade-offs between environments, but trade-offs are difficult to invoke for species with similar ecological niches. Such similar species might then go locally extinct due to stochastic ecological drift, but there is little empirical evidence for such processes. Previous studies have relied on biogeographical surveys and inferred process from pattern, while experimental field investigations of ecological drift are rare. Mechanisms preserving local species diversity, such as frequency dependence (e.g., rare-species advantages), can oppose local ecological drift, but the combined effects of ecological drift and such counteracting forces have seldom been investigated. Here, we investigate mechanisms between coexistence of ecologically similar but strongly sexually differentiated damselfly species (Calopteryx virgo and Calopteryx splendens). Combining field surveys, behavioral observations, experimental manipulations of species frequencies and densities, and simulation modeling, we demonstrate that species coexistence is shaped by the opposing forces of ecological drift and negative frequency dependence (rare-species advantage), generated by interference competition. Stochastic and deterministic processes therefore jointly shape coexistence. The role of negative frequency dependence in delaying the loss of ecologically similar species, such as those formed by sexual selection, should therefore be considered in community assembly, macroecology, macroevolution, and biogeography.

BAMBI (BMP and activin membrane-bound inhibitor) protects the murine heart from pressure-overload biomechanical stress by restraining TGF-ß signaling.

Left ventricular (LV) pressure overload is a major cause of heart failure. Transforming growth factors-ß (TGF-ßs) promote LV remodeling under biomechanical stress. BAMBI (BMP and activin membrane-bound inhibitor) is a pseudoreceptor that negatively modulates TGF-ß signaling. The present study tests the hypothesis that BAMBI plays a protective role during the adverse LV remodeling under pressure overload. The subjects of the study were BAMBI knockout mice (BAMBI(-/-)) undergoing transverse aortic constriction (TAC) and patients with severe aortic stenosis (AS). We examined LV gene and protein expression of remodeling-related elements, histological fibrosis, and heart morphology and function. LV expression of BAMBI was increased in AS patients and TAC-mice and correlated directly with TGF-ß. BAMBI deletion led to a gain of myocardial TGF-ß signaling through canonical (Smads) and non-canonical (TAK1-p38 and TAK1-JNK) pathways. As a consequence, the remodeling response to pressure overload in BAMBI(-/-) mice was exacerbated in terms of hypertrophy, chamber dilation, deterioration of long-axis LV systolic function and diastolic dysfunction. Functional remodeling associated transcriptional activation of fibrosis-related TGF-ß targets, up-regulation of the profibrotic micro-RNA-21, histological fibrosis and increased metalloproteinase-2 activity. Histological remodeling in BAMBI(-/-) mice involved TGF-ßs. BAMBI deletion in primary cardiac fibroblasts exacerbated TGF-ß-induced profibrotic responses while BAMBI overexpression in NIH-3T3 fibroblasts attenuated them. Our findings identify BAMBI as a critical negative modulator of myocardial remodeling under pressure overload. We suggest that BAMBI is involved in negative feedback loops that restrain the TGF-ß remodeling signals to protect the pressure-overloaded myocardium from uncontrolled extracellular matrix deposition in humans and mice.

Male harm suppresses female fitness, affecting the dynamics of adaptation and evolutionary rescue.

One of the most pressing questions we face as biologists is to understand how climate change will affect the evolutionary dynamics of natural populations and how these dynamics will in turn affect population recovery. Increasing evidence shows that sexual selection favors population viability and local adaptation. However, sexual selection can also foster sexual conflict and drive the evolution of male harm to females. Male harm is extraordinarily widespread and has the potential to suppress female fitness and compromise population growth, yet we currently ignore its net effects across taxa or its influence on local adaptation and evolutionary rescue. We conducted a comparative meta-analysis to quantify the impact of male harm on female fitness and found an overall negative effect of male harm on female fitness. Negative effects seem to depend on proxies of sexual selection, increasing inversely to the female relative size and in species with strong sperm competition. We then developed theoretical models to explore how male harm affects adaptation and evolutionary rescue. We show that, when sexual conflict depends on local adaptation, population decline is reduced, but at the cost of slowing down genetic adaptation. This trade-off suggests that eco-evolutionary feedback on sexual conflict can act like a double-edged sword, reducing extinction risk by buffering the demographic costs of climate change, but delaying genetic adaptation. However, variation in the mating system and male harm type can mitigate this trade-off. Our work shows that male harm has widespread negative effects on female fitness and productivity, identifies potential mechanistic factors underlying variability in such costs across taxa, and underscores how acknowledging the condition-dependence of male harm may be important to understand the demographic and evolutionary processes that impact how species adapt to environmental change.

Clinical comparison of a handheld cardiac ultrasound device for the assessment of left ventricular function.

PURPOSE: Recently developed handheld ultrasound devices (HHUD) represent a promising method to evaluate the cardiovascular abnormalities at the point of care. However, this technology has not been rigorously evaluated. The aim of this study was to explore the correlation and the agreement between the LVEF (Left Ventricular Ejection Fraction) visually assessed by a moderately experienced sonographer using an HHUD compared to the routine LVEF assessment performed at the Echocardiography Laboratory. METHODS: This was a prospective single center study which enrolled 120 adult inpatients and outpatients referred for a comprehensive Echocardiography (EC). RESULTS: The mean age of the patients was 69.9 ± 12.5 years. There were 47 females (39.2%). The R-squared was r 0.94 (p < 0.0001) and the ICC was 0.93 (IC 95% 0.91-0.95, p ≤ 0.0001). The Bland-Altman plot showed limits of agreement (LOA): Upper LOA 10.61 and Lower LOA - 8.95. The overall agreement on the LVEF assessment when it was stratified as "normal" or "reduced" was 89.1%, with a kappa of 0.77 (p < 0.0001). When the LVEF was classified as "normal", "mildly reduced", "moderately reduced", or "severely reduced," the kappa was 0.77 (p < 0.0001). The kappa between the HHUD EC and the comprehensive EC for the detection of RWMAs in the territories supplied by the LAD, LCX and RCA was 0.85, 0.73 and 0.85, respectively. CONCLUSION: With current HHUD, an averagely experienced operator can accurately bedside visual estimate the LVEF. This may facilitate the incorporation of this technology in daily clinical practice improving the management of patients.

When and how can we predict adaptive responses to climate change?

Predicting if, when, and how populations can adapt to climate change constitutes one of the greatest challenges in science today. Here, we build from contributions to the special issue on evolutionary adaptation to climate change, a survey of its authors, and recent literature to explore the limits and opportunities for predicting adaptive responses to climate change. We outline what might be predictable now, in the future, and perhaps never even with our best efforts. More accurate predictions are expected for traits characterized by a well-understood mapping between genotypes and phenotypes and traits experiencing strong, direct selection due to climate change. A meta-analysis revealed an overall moderate trait heritability and evolvability in studies performed under future climate conditions but indicated no significant change between current and future climate conditions, suggesting neither more nor less genetic variation for adapting to future climates. Predicting population persistence and evolutionary rescue remains uncertain, especially for the many species without sufficient ecological data. Still, when polled, authors contributing to this special issue were relatively optimistic about our ability to predict future evolutionary responses to climate change. Predictions will improve as we expand efforts to understand diverse organisms, their ecology, and their adaptive potential. Advancements in functional genomic resources, especially their extension to non-model species and the union of evolutionary experiments and "omics," should also enhance predictions. Although predicting evolutionary responses to climate change remains challenging, even small advances will reduce the substantial uncertainties surrounding future evolutionary responses to climate change.

Outcome and improvement predictors of mitral regurgitation after transcatheter aortic valve implantation.

BACKGROUND AND AIM OF THE STUDY: Mitral regurgitation (MR) is frequently present in patients with calcific aortic stenosis (AS). Yet, the issue of whether to surgically correct the MR during aortic valve replacement (AVR) remains uncertain. The study aim was to define the outcome of MR after transcatheter aortic valve implantation (TAVI) in the TRanscatheter EndoVascular Implantation of VALves (REVIVAL) II trial. METHODS: Echocardiography was performed before and at 24 h, and three and six months after valve implantation. The degree of MR was evaluated by expert readers and by the vena contracta (VC) method. Significant MR was defined as at least mild to moderate MR. Those patients with a 30% reduction in VC were classified as good responders (GR group), and the remainder as poor responders (PR group). RESULTS: The study comprised 35 subjects with at least mild to moderate MR before TAVI. The mean VC of the whole group declined from 0.5 +/- 0.2 cm initially to 0.32 +/- 0.2 cm and 0.38 +/- 0.2 cm at 24 h and three months, respectively (p < 0.05). At three months, 12 patients had > 30% VC reduction; these constituted the GR group, while the remainder constituted the PR group. The percentage of patients with mitral annular calcification with restriction (MACr), defined as calcification encroaching onto the leaflets and restricting leaflet motion, was significantly lower in the GR group compared to the PR group (17% versus 61%, respectively; p < 0.05). The remaining pre-specified parameters did not differ significantly between the GR and PR groups, including age, gender, mitral valve tethering height and area (6 +/- 2 mm versus 5 +/- 3 mm and 10 +/- 4 mm2 versus 13 +/- 9 and 10 +/- 4 mm2, respectively), change in the aortic valve area (336 +/- 130% versus 285 +/- 180%), change in mean systolic aortic valve pressure (-20 +/- 8% versus - 23 +/- 10%), and left ventricular ejection fraction (47 +/- 15% versus 45 +/- 18%). CONCLUSION: MR is improved significantly after TAVI for AS. MACr was the only variable associated with a reduction in MR improvement. These results suggest that a careful echocardiographic evaluation of the mitral valve prior to TAVI may help to predict which patients should experience an improvement in their MR.

The importance of pre- and postcopulatory sexual selection promoting adaptation to increasing temperatures.

Global temperatures are increasing rapidly affecting species globally. Understanding if and how different species can adapt fast enough to keep up with increasing temperatures is of vital importance. One mechanism that can accelerate adaptation and promote evolutionary rescue is sexual selection. Two different mechanisms by which sexual selection can facilitate adaptation are pre- and postcopulatory sexual selection. However, the relative effects of these different forms of sexual selection in promoting adaptation are unknown. Here, we present the results from an experimental study in which we exposed fruit flies Drosophila melanogaster to either no mate choice or 1 of 2 different sexual selection regimes (pre- and postcopulatory sexual selection) for 6 generations, under different thermal regimes. Populations showed evidence of thermal adaptation under precopulatory sexual selection, but this effect was not detected in the postcopulatory sexual selection and the no choice mating regime. We further demonstrate that sexual dimorphism decreased when flies evolved under increasing temperatures, consistent with recent theory predicting more sexually concordant selection under environmental stress. Our results suggest an important role for precopulatory sexual selection in promoting thermal adaptation and evolutionary rescue.

When Ecology Fails: How Reproductive Interactions Promote Species Coexistence.

That species must differ ecologically is often viewed as a fundamental condition for their stable coexistence in biological communities. Yet, recent work has shown that ecologically equivalent species can coexist when reproductive interactions and sexual selection regulate population growth. Here, we review theoretical models and highlight empirical studies supporting a role for reproductive interactions in maintaining species diversity. We place reproductive interactions research within a burgeoning conceptual framework of coexistence theory, identify four key mechanisms in intra- and interspecific interactions within and between sexes, speculate on novel mechanisms, and suggest future research. Given the preponderance of sexual reproduction in nature, our review suggests that this is a neglected path towards explaining species diversity when traditional ecological explanations have failed.

Gender differences of echocardiographic and gene expression patterns in human pressure overload left ventricular hypertrophy.

Gender influence on left ventricular (LV) remodeling associated to aortic valve stenosis (AS) has been long recognized, but underlying myocardial gene expression patterns have not been explored. We studied whether sex differences in echocardiographic LV anatomy and function in AS patients are associated with specific changes in myocardial mRNA expression of remodeling proteins. AS (n=39) and control (n=23)patients were assessed echocardiographically, and LV myocardial mRNA levels were quantified by PCR. AS patients exhibit increased wall thicknesses and LV mass index (LVMI), but only men show chamber dilation.Collagens and fibronectin mRNA levels increased correlatively to transforming growth factor-beta1 (TGF-beta1). In AS women, collagen I upregulation was proportionally higher than other extracellular matrix (ECM)components. No changes in matrix metalloproteinase-2 and tissue inhibitor of metalloproteinase-2 were detected. Gene expressions of sarcomeric proteins (beta-myosin heavy chain and myosin light chain-2) and TGF-beta1 were directly correlated with each other. Myosin light chain-2 mRNA levels increased proportionally to the transvalvular gradient, but women did so in a greater extent than men for a given gradient. In women, the hypertrophic growth response, reflected by LVMI, was proportional to the expression of genes encoding sarcomeric proteins and TGF-beta1. In men, chamber dilation and deterioration of LVEF was proportional to collagens, fibronectin, and TGF-beta1 gene expression levels. We evidenced gender biased gene expression patterns of the intracellular TGF-beta pathways involving the Smad branch, but not the TAK-1 branch, that could contribute to the remodeling differences observed in AS men and women. Based on these findings, a gender specific therapeutic approach of pressure overload LV hypertrophy could be justified.

Risk factors, clinical features, and outcomes of listeriosis in solid-organ transplant recipients: a matched case-control study.

BACKGROUND: Solid-organ transplant (SOT) recipients are classically considered to be at increased risk for listeriosis. However, risk factors for this infection have not been assessed. METHODS: We carried out a multicenter, matched case-control study (1:2 ratio) from January 1995 through December 2007. Control subjects were matched for center, transplant type, and timing. Conditional logistic regression was performed to identify independent risk factors. Clinical features and outcomes for all case patients were reviewed. RESULTS: Thirty patients (0.12%) with cases of listeriosis were identified among 25,997 SOT recipients at 15 Spanish transplant centers. In a comparison of case patients with 60 matched control subjects, the following independent risk factors for listeriosis were identified: diabetes mellitus (odds ratio [OR], 5.6; 95% confidence interval [CI], 1.6-19.6; ), P = .007 history of cytomegalovirus infection or disease within the preceding 6 months (OR, 35.9; 95% CI, 2.1-620; P = .014), receipt of high-dose prednisone within the preceding 6 months (OR, 6.2; 95% CI, 1.8-21.1; P = .003), and trimethoprim-sulfamethoxazole (TMP-SMZ) prophylaxis (OR, 0.07; 95% CI, 0.006-0.76; P = .029). Twenty-six patients (86.7%) had bacteremia, and 7 had shock at presentation. Other manifestations included meningoencephalitis (10 cases), spontaneous peritonitis (2), pleural empyema (1), brain abscesses (1), and liver abscesses (1). The 30-day mortality rate was 26.7% (8 of 30 patients died). CONCLUSIONS: Listeriosis in SOT recipients is uncommon but causes high mortality. Diabetes mellitus, cytomegalovirus infection or disease, and receipt of high-dose steroids are independent risk factors for this infection, whereas TMP-SMZ prophylaxis is a protective factor.

Utility of implantable loop recorders for diagnosing unexplained syncope in clinical practice.

BACKGROUND: Establishing a symptom-rhythm correlation in patients with unexplained syncope is complicated because of its sporadic, infrequent, and unpredictable nature. Prolonged monitoring with an implantable loop recorder (ILR) allows the recording of electrocardiogram (ECG) data from a spontaneous syncopal event. HYPOTHESIS: The aim of this study was to evaluate the usefulness of the ILR for the diagnosis of syncope of unknown origin after conventional management in clinical practice. METHODS: We reviewed the results with ILR implantation in patients with syncope of unknown origin after conventional management in the cardiology department at HU Marques de Valdecilla (Santander, Cantabria, Spain). RESULTS: One hundred and forty patients (age 64 +/- 16 y; 86 male [62%]) with syncope of unknown etiology after conventional work-up underwent prolonged monitoring with an ILR from September 1998 to February 2006; 46 patients (33%) had structural heart disease. During a mean follow-up of 346 +/- 160 d, 51 patients (36.5%) had recurrent syncope with diagnostic ECG recording. An arrhythmic cause for syncope was found in 33 of them (64.5%), with bradycardia present in 27 (53%) and tachycardia in 6 (11%). There were no sudden deaths, and 1 patient suffered a complication related to a recurrence of syncope. CONCLUSION: Long-time experience with the ILR confirmed the utility of this device in the diagnosis of unexplained syncope in clinical practice. Most of these patients had syncope of arrhythmogenic etiology that could be successfully treated. This strategy of prolonged monitoring is safe even in patients with structural heart disease.

Experimental modelling of cardiac pressure overload hypertrophy: Modified technique for precise, reproducible, safe and easy aortic arch banding-debanding in mice.

Pressure overload left ventricular hypertrophy is a known precursor of heart failure with ominous prognosis. The development of experimental models that reproduce this phenomenon is instrumental for the advancement in our understanding of its pathophysiology. The gold standard of these models is the controlled constriction of the mid aortic arch in mice according to Rockman's technique (RT). We developed a modified technique that allows individualized and fully controlled constriction of the aorta, improves efficiency and generates a reproducible stenosis that is technically easy to perform and release. An algorithm calculates, based on the echocardiographic arch diameter, the intended perimeter at the constriction, and a suture is prepared with two knots separated accordingly. The aorta is encircled twice with the suture and the loop is closed with a microclip under both knots. We performed controlled aortic constriction with Rockman's and the double loop-clip (DLC) techniques in mice. DLC proved superiority in efficiency (mortality and invalid experiments) and more homogeneity of the results (transcoarctational gradients, LV mass, cardiomyocyte hypertrophy, gene expression) than RT. DLC technique optimizes animal use and generates a consistent and customized aortic constriction with homogeneous LV pressure overload morphofunctional, structural, and molecular features.

Sexual conflict and ecology: Species composition and male density interact to reduce male mating harassment and increase female survival.

Sexual conflict is a pervasive evolutionary force that can reduce female fitness. Experimental evolution studies in the laboratory might overestimate the importance of sexual conflict because the ecological conditions in such settings typically include only a single species. Here, we experimentally manipulated conspecific male density (high or low) and species composition (sympatric or allopatric) to investigate how ecological conditions affect female survival in a sexually dimorphic insect, the banded demoiselle (Calopteryx splendens). Female survival was strongly influenced by an interaction between male density and species composition. Specifically, at low conspecific male density, female survival increased in the presence of heterospecific males (C. virgo). Behavioral mating experiments showed that interspecific interference competition reduced conspecific male mating success with large females. These findings suggest that reproductive interference competition between con- and heterospecific males might indirectly facilitate female survival by reducing mating harassment from conspecific males. Hence, interspecific competitors can show contrasting effects on the two sexes thereby influencing sexual conflict dynamics. Our results call for incorporation of more ecological realism in sexual conflict research, particularly how local community context and reproductive interference competition between heterospecific males can affect female fitness.

Sex differences in local adaptation: what can we learn from reciprocal transplant experiments?

Local adaptation is of fundamental interest to evolutionary biologists. Traditionally, local adaptation has been studied using reciprocal transplant experiments to quantify fitness differences between residents and immigrants in pairwise transplants between study populations. Previous studies have detected local adaptation in some cases, but others have shown lack of adaptation or even maladaptation. Recently, the importance of different fitness components, such as survival and fecundity, to local adaptation have been emphasized. Here, we address another neglected aspect in studies of local adaptation: sex differences. Given the ubiquity of sexual dimorphism in life histories and phenotypic traits, this neglect is surprising, but may be partly explained by differences in research traditions and terminology in the fields of local adaptation and sexual selection. Studies that investigate differences in mating success between resident and immigrants across populations tend to be framed in terms of reproductive and behavioural isolation, rather than local adaptation. We briefly review the published literature that bridges these areas and suggest that reciprocal transplant experiments could benefit from quantifying both male and female fitness components. Such a more integrative research approach could clarify the role of sex differences in the evolution of local adaptations.This article is part of the theme issue 'Linking local adaptation with the evolution of sex differences'.

The coevolution of sexual imprinting by males and females.

Sexual imprinting is the learning of a mate preference by direct observation of the phenotype of another member of the population. Sexual imprinting can be paternal, maternal, or oblique if individuals learn to prefer the phenotypes of their fathers, mothers, or other members of the population, respectively. Which phenotypes are learned can affect trait evolution and speciation rates. "Good genes" models of polygynous systems predict that females should evolve to imprint on their fathers, because paternal imprinting helps females to choose mates that will produce offspring that are both viable and sexy. Sexual imprinting by males has been observed in nature, but a theory for the evolution of sexual imprinting by males does not exist. We developed a good genes model to study the conditions under which sexual imprinting by males or by both sexes can evolve and to ask which sexual imprinting strategies maximize the fitness of the choosy sex. We found that when only males imprint, maternal imprinting is the most advantageous strategy. When both sexes imprint, it is most advantageous for both sexes to use paternal imprinting. Previous theory suggests that, in a given population, either males or females but not both will evolve choosiness in mating. We show how environmental change can lead to the evolution of sexual imprinting behavior by both sexes in the same population.