Ecological predictors of interspecific variation in bird bill and leg lengths on a global scale.

Bills and legs are two vital appendages for birds, and they exhibit huge interspecific variation in form and function, yet no study has examined the global predictors of this variation. This study examined global gradients in the relative lengths of bird bills and tarsi (i.e. exposed leg parts) to body size across non-migratory birds, while accounting for phylogeny. We found that relative bill length and tarsus length were related to diet, habitat density, latitude, annual mean temperature, temperature variability and hand-wing index (HWI), a proxy for birds' flight efficiency. Among these factors, diet played a primary role in predicting bill length, with nectar-feeding pollinators, vertivores, invertivores and omnivores having longer bills; HWI emerged as the predominant predictor of tarsus length, wherein species with higher HWI had shorter tarsi. However, the effects of these factors differed between passerines and non-passerines, with some temperature-related effects exhibiting opposite trends between these two groups. Our findings highlight the compromise in adaptations for feeding, thermoregulation and flight performance between the two distinct appendages.

Highly conserved thermal performance strategies may limit adaptive potential in corals.

Increasing seawater temperatures are expected to have profound consequences for reef-building corals' physiology. Understanding how demography changes in response to chronic exposure to warming will help forecast how coral communities will respond to climate change. Here, we measure growth rates of coral fragments of four common species, while exposing them to temperatures ranging from 19°C to 31°C for one month to calibrate their thermal-performance curves (TPCs). Our results show that, while there are contrasting differences between species, the shape of the TPCs was remarkably consistent among individuals of the same species. The low variation in thermal sensitivity within species may imply a reduced capacity for rapid adaptive responses to future changes in thermal regimes. Additionally, interspecific differences in thermal responses show a negative relationship between maximum growth and thermal optima, contradicting expectations derived from the classic 'warmer-is-better' hypothesis. Among species, there was a trade-off between current and future growth, whereby most species perform well under current thermal regimes but are susceptible to future increases in temperature. Increases in water temperature with climate change are likely to reduce growth rates, further hampering future coral reef recovery rates and potentially altering community composition.

A new approach to an old problem: how to categorize the habit of ferns and lycophytes.

BACKGROUND AND AIMS: Substrate preferences are often treated as species traits and are used to distinguish different habits, i.e. an epiphytic, lithophytic or terrestrial habit. Such a categorization, however, ignores substantial intraspecific variation. An approach that takes biological variability within a species into account is needed. METHODS: We focused on four large genera of ferns and lycophytes and found relevant information in >500 sources, such as online databases, checklists, floras and species descriptions. Translating textual information into a quantitative index, we quantified the propensity to grow on either substrate as a continuous trait for 1475 species. KEY RESULTS: Only a minority of species exhibited strict substrate fidelity, but a majority of them showed clear habitat preferences. The relative frequencies of intermediates between strict lithophytes, epiphytes and terrestrials does not support the frequent notion of ecological similarity of the lithophytic and epiphytic habitat. CONCLUSIONS: The compiled data are useful immediately for ecological and evolutionary studies with the focal taxa. More importantly, we propose the replacement of the concept of distinct habits with one of gradual differences. This should have a profound impact on any such study with plants in general.

Variation in ripe fruit volatiles across the tomato clade: An evolutionary framework for studying fruit scent diversity in a crop wild relative.

PREMISE: The scents of volatile organic compounds (VOCs) are an important component of ripe fleshy fruit attractiveness, yet their variation across closely related wild species is poorly understood. Phylogenetic patterns in these compounds and their biosynthetic pathways offer insight into the evolutionary drivers of fruit diversity, including whether scent can communicate an honest signal of nutrient content to animal dispersers. We assessed ripe fruit VOC content across the tomato clade (Solanum sect. Lycopersicon), with implications for crop improvement since these compounds are key components of tomato flavor. METHODS: We analyzed ripe fruit volatiles from 13 species of wild tomato grown in a common garden. Interspecific variations in 66 compounds and their biosynthetic pathways were assessed in 32 accessions, and an accession-level phylogeny was constructed to account for relatedness. RESULTS: Wild tomato species can be differentiated by their VOCs, with Solanum pennellii notably distinct. Phylogenetic conservatism exists to a limited extent. Major cladewide patterns corresponded to divergence of the five brightly colored-fruited species from the nine green-fruited species, particularly for nitrogen-containing compounds (higher in colored-fruited) and esters (higher in green-fruited), the latter appearing to signal a sugar reward. CONCLUSIONS: We established a framework for fruit scent evolution studies in a crop wild relative system, showing that each species in the tomato clade has a unique VOC profile. Differences between color groups align with fruit syndromes that could be driven by selection from frugivores. The evolution of colored fruits was accompanied by changes in biosynthetic pathways for esters and nitrogen-containing compounds, volatiles important to tomato flavor.

Taxonomic insights from floral scents of western North American sessile-flowered Trillium.

PREMISE: Chemical composition of floral volatiles can be an important complement to morphological characters in describing and identifying species. Four of the five species of western sessile-flowered Trillium are challenging to distinguish morphologically due to wide intraspecific variation and overlapping characters among taxa. Characterizing their floral volatile compositions could aid future taxonomic, ecological, and evolutionary studies of Trillium and related taxa. We addressed two major questions: How do western sessile Trillium taxa vary in floral chemistry? Can floral scent be used to distinguish species? METHODS: We collected petals from 600 individuals at 42 wild populations of four sessile Trillium species across California, Oregon, and Washington. Volatile organic compounds from the petals were extracted using solid-phase microextraction, and the volatiles were identified and quantified by gas chromatography-mass spectrometry. The utility of floral scent composition in distinguishing species was tested using nonmetric multidimensional scaling and random forest analysis. RESULTS: Floral volatiles of the white-petaled T. albidum were dominated by oxygenated monoterpenes and showed considerable geographic variation that paralleled morphological variation. The maroon-petaled T. angustipetalum and T. kurabayashii produced floral scents characterized by aliphatic esters, but each had a distinct chemical composition. Petal color of Trillium chloropetalum is highly variable, as were its scent compositions, which were blends of volatiles from both white-petaled and maroon-petaled congeneric taxa. CONCLUSIONS: Differences in floral scent compositions are consistent with current taxonomy of the western sessile Trillium group. In cases where species delimitations are difficult based on morphology, floral scent composition provides taxonomic insight and suggests a potential hybrid origin for T. chloropetalum.

Geometric morphometric variability in the supraorbital and orbital region of Middle Pleistocene hominins: Implications for the taxonomy and evolution of later Homo.

This study assessed variation in the supraorbital and orbital region of the Middle Pleistocene hominins (MPHs), sometimes called Homo heidelbergensis s.l., to test whether it matched the expectations of intraspecific variation. The morphological distinctiveness and relative variation of this region, which is relatively well represented in the hominin fossil record, was analyzed quantitatively in a comparative taxonomic framework. Coordinates of 230 3D landmarks (20) and sliding semilandmarks (210) were collected from 704 specimens from species of Homo, Australopithecus, Paranthropus, Gorilla, Pan, Papio, and Macaca. Results showed that the MPHs had expected levels of morphological distinctiveness and intragroup and intergroup variation in supraorbital and orbital morphology, relative to commonly recognized non-hominin catarrhine species. However, the Procrustes distances between this group and H. sapiens were significantly higher than expected for two closely related catarrhine species. Furthermore, this study showed that variation within the MPH could be similarly well contained within existing hypodigms of H. sapiens, H. neanderthalensis, and H. erectus s.l. Although quantitative assessment of supraorbital and orbital morphology did not allow differentiation between taxonomic hypotheses in later Homo, it could be used to test individual taxonomic affiliation and identify potentially anomalous individuals. This study confirmed a complicated pattern of supraorbital and orbital morphology in the MPH fossil record and raises further questions over our understanding of the speciation of H. sapiens and H. neanderthalensis and taxonomic diversity in later Homo.

Interspecific variation in resistance and tolerance to herbicide drift reveals potential consequences for plant community co-flowering interactions and structure at the agro-eco interface.

BACKGROUND AND AIMS: When plant communities are exposed to herbicide 'drift', wherein particles containing the active ingredient travel off-target, interspecific variation in resistance or tolerance may scale up to affect community dynamics. In turn, these alterations could threaten the diversity and stability of agro-ecosystems. We investigated the effects of herbicide drift on the growth and reproduction of 25 wild plant species to make predictions about the consequences of drift exposure on plant-plant interactions and the broader ecological community. METHODS: We exposed potted plants from species that commonly occur in agricultural areas to a drift-level dose of the widely used herbicide dicamba or a control solution in the glasshouse. We evaluated species-level variation in resistance and tolerance for vegetative and floral traits. We assessed community-level impacts of drift by comparing the species evenness and flowering networks of glasshouse synthetic communities comprised of drift-exposed and control plants. KEY RESULTS: Species varied significantly in resistance and tolerance to dicamba drift: some were negatively impacted while others showed overcompensatory responses. Species also differed in the way they deployed flowers over time following drift exposure. While drift had negligible effects on community evenness based on vegetative biomass, it caused salient differences in the structure of co-flowering networks within communities. Drift reduced the degree and intensity of flowering overlap among species, altered the composition of groups of species that were more likely to co-flower with each other than with others and shifted species roles (e.g. from dominant to inferior floral producers, and vice versa). CONCLUSIONS: These results demonstrate that even low levels of herbicide exposure can significantly alter plant growth and reproduction, particularly flowering phenology. If field-grown plants respond similarly, then these changes would probably impact plant-plant competitive dynamics and potentially plant-pollinator interactions occurring within plant communities at the agro-ecological interface.

Variation in the Transcriptome Response and Detoxification Gene Diversity Drives Pesticide Tolerance in Fishes.

Pesticides are critical for invasive species management but often have negative effects on nontarget native biota. Tolerance to pesticides should have an evolutionary basis, but this is poorly understood. Invasive sea lamprey (Petromyzon marinus) populations in North America have been controlled with a pesticide lethal to them at lower concentrations than native fishes. We addressed how interspecific variation in gene expression and detoxification gene diversity confer differential pesticide sensitivity in two fish species. We exposed sea lamprey and bluegill (Lepomis macrochirus), a tolerant native species, to 3-trifluoromethyl-4-nitrophenol (TFM), a pesticide commonly used in sea lamprey control. We then used whole-transcriptome sequencing of gill and liver to characterize the cellular response in both species. Comparatively, bluegill exhibited a larger number of detoxification genes expressed and a larger number of responsive transcripts overall, which likely contributes to greater tolerance to TFM. Understanding the genetic and physiological basis for pesticide tolerance is crucial for managing invasive species.

Capoeta ekmekciae Turan, Kottelat, Kirankaya & Engin, 2006, a junior synonym of Capoeta capoeta (Güldenstädt, 1773) (Teleostei: Cyprinidae).

Some recent works have proposed that Capoeta ekmekciae from the Çoruh River and C. capoeta from the Kura-Aras River system are synonyms based on molecular data, which prompted this study to compare their morphometric, meristic and molecular data to investigate this hypothesis. Based on the results, the C. ekmekciae form displays morphometric and meristic traits quite similar to the C. capoeta form. Since there are no diagnostic traits to distinguish these two allopatric species from each other and they share identical cytb gene, we treat C. ekmekciae as a junior synonym of C. capoeta.

Comparative morphometric analyses of the deciduous molars of Homo naledi from the Dinaledi Chamber, South Africa.

OBJECTIVES: The purpose of this study is to help elucidate the taxonomic relationship between Homo naledi and other hominins. MATERIALS AND METHODS: Homo naledi deciduous maxillary and mandibular molars from the Dinaledi Chamber, South Africa were compared to those of Australopithecus africanus, Australopithecus afarensis, Paranthropus robustus, Paranthropus boisei, early Homo sp., Homo erectus, early Homo sapiens, Upper Paleolithic H. sapiens, recent southern African H. sapiens, and Neanderthals by means of morphometric analyses of crown outlines and relative cusp areas. The crown shapes were analyzed using elliptical Fourier analyses followed by principal component analyses (PCA). The absolute and relative cusp areas were obtained in ImageJ and compared using PCA and cluster analyses. RESULTS: PCA suggests that the crown shapes and relative cusp areas of mandibular molars are more diagnostic than the maxillary molars. The H. naledi deciduous mandibular first and second molar (dm1 and dm2 ) do not have a strong affinity to any taxon in the comparative sample in all analyses. While the H. naledi dm2 plots as an outlier in the relative cusp analysis, the H. naledi specimen fall closest to Australopithecus due to their relatively large metaconid, a primitive trait for the genus Homo. Although useful for differentiating Neanderthals from recent southern African H. sapiens and UP H. sapiens, the PCA of the relative cusp areas suggests that the deciduous maxillary second molars (dm2 ) do not differentiate other groups. The three H. naledi dm2 cuspal areas are variable and fall within the ranges of other Homo, as well as Australopithecus, and Paranthropus suggesting weak diagnostic utility. DISCUSSION: This research provides another perspective on the morphology of, and variation within, H. naledi. The H. naledi deciduous molars do not consistently align with any genus or species in the comparative sample in either the crown shape or relative cusp analyses. This line of inquiry is consistent with other cranial and postcranial studies suggesting that H. naledi is unique.

Explaining variation in Colorado songbird blood mercury using migratory behavior, foraging guild, and diet.

Methylmercury is a contaminant of growing global concern that has been shown to accumulate in a variety of taxa, including songbirds. Birds in the same area can accumulate mercury to strikingly different levels. While diet and trophic level clearly play an important role in mercury bioaccumulation and biomagnification, other factors including foraging guilds and migratory behavior may influence mercury levels as well. Here we examine interspecific variation in blood mercury levels in songbirds living in the Fountain Creek watershed on the Front Range of Colorado. We found that the species with the highest mercury had blood mercury concentrations over 75 times higher than the species with the lowest levels. Carnivores had the highest blood mercury levels, but ground foraging and long distance migration also were correlated with higher mercury concentrations. This information may shed light on what species are most at risk from mercury pollution and help to target conservation resources at contaminated sites.

Tradeoffs among root morphology, exudation and mycorrhizal symbioses for phosphorus-acquisition strategies of 16 crop species.

Plant roots exhibit diverse root functional traits to enable soil phosphorus (P) acquisition, including changes in root morphology, root exudation and mycorrhizal symbioses. Yet, whether these traits are differently coordinated among crop species to enhance P acquisition is unclear. Here, eight root functional traits for P acquisition were characterized in 16 major herbaceous crop species grown in a glasshouse under limiting and adequate soil P availability. We found substantial interspecific variation in root functional traits among species. Those with thinner roots showed more root branching and less first-order root length, and had consistently lower colonization by arbuscular mycorrhizal fungi (AMF), fewer rhizosheath carboxylates and reduced acid phosphatase activity. In response to limiting soil P, species with thinner roots showed a stronger response in root branching, first-order root length and specific root length of the whole root system, Conversely, species with thicker roots exhibited higher colonization by AMF and/or more P-mobilizing exudates in the rhizosheath. We conclude that, at the species level, tradeoffs occur among the three groups of root functional traits we examined. Root diameter is a good predictor of the relative expression of these traits and how they change when P is limiting.

Comparative genomics of Rhizophagus irregularis, R. cerebriforme, R. diaphanus and Gigaspora rosea highlights specific genetic features in Glomeromycotina.

Glomeromycotina is a lineage of early diverging fungi that establish arbuscular mycorrhizal (AM) symbiosis with land plants. Despite their major ecological role, the genetic basis of their obligate mutualism remains largely unknown, hindering our understanding of their evolution and biology. We compared the genomes of Glomerales (Rhizophagus irregularis, Rhizophagus diaphanus, Rhizophagus cerebriforme) and Diversisporales (Gigaspora rosea) species, together with those of saprotrophic Mucoromycota, to identify gene families and processes associated with these lineages and to understand the molecular underpinning of their symbiotic lifestyle. Genomic features in Glomeromycotina appear to be very similar with a very high content in transposons and protein-coding genes, extensive duplications of protein kinase genes, and loss of genes coding for lignocellulose degradation, thiamin biosynthesis and cytosolic fatty acid synthase. Most symbiosis-related genes in R. irregularis and G. rosea are specific to Glomeromycotina. We also confirmed that the present species have a homokaryotic genome organisation. The high interspecific diversity of Glomeromycotina gene repertoires, affecting all known protein domains, as well as symbiosis-related orphan genes, may explain the known adaptation of Glomeromycotina to a wide range of environmental settings. Our findings contribute to an increasingly detailed portrait of genomic features defining the biology of AM fungi.

Adjustments and coordination of hydraulic, leaf and stem traits along a water availability gradient.

Trait variability in space and time allows plants to adjust to changing environmental conditions. However, we know little about how this variability is distributed and coordinated at different organizational levels. For six dominant tree species in northeastern Spain (three Fagaceae and three Pinaceae) we quantified the inter- and intraspecific variability of a set of traits along a water availability gradient. We measured leaf mass per area (LMA), leaf nitrogen (N) concentration, carbon isotope composition in leaves (δ13 C), stem wood density, the Huber value (Hv, the ratio of cross-sectional sapwood area to leaf area), sapwood-specific and leaf-specific stem hydraulic conductivity, vulnerability to xylem embolism (P50 ) and the turgor loss point (Ptlp ). Differences between families explained the largest amount of variability for most traits, although intraspecific variability was also relevant. Species occupying wetter sites showed higher N, P50 and Ptlp , and lower LMA, δ13 C and Hv. However, when trait relationships with water availability were assessed within species they held only for Hv and Ptlp . Overall, our results indicate that intraspecific adjustments along the water availability gradient relied primarily on changes in resource allocation between sapwood and leaf area and in leaf water relations.

ATLANTIC MAMMAL TRAITS: a data set of morphological traits of mammals in the Atlantic Forest of South America.

Measures of traits are the basis of functional biological diversity. Numerous works consider mean species-level measures of traits while ignoring individual variance within species. However, there is a large amount of variation within species and it is increasingly apparent that it is important to consider trait variation not only between species, but also within species. Mammals are an interesting group for investigating trait-based approaches because they play diverse and important ecological functions (e.g., pollination, seed dispersal, predation, grazing) that are correlated with functional traits. Here we compile a data set comprising morphological and life history information of 279 mammal species from 39,850 individuals of 388 populations ranging from -5.83 to -29.75 decimal degrees of latitude and -34.82 to -56.73 decimal degrees of longitude in the Atlantic forest of South America. We present trait information from 16,840 individuals of 181 species of non-volant mammals (Rodentia, Didelphimorphia, Carnivora, Primates, Cingulata, Artiodactyla, Pilosa, Lagomorpha, Perissodactyla) and from 23,010 individuals of 98 species of volant mammals (Chiroptera). The traits reported include body mass, age, sex, reproductive stage, as well as the geographic coordinates of sampling for all taxa. Moreover, we gathered information on forearm length for bats and body length and tail length for rodents and marsupials. No copyright restrictions are associated with the use of this data set. Please cite this data paper when the data are used in publications. We also request that researchers and teachers inform us of how they are using the data.

Sexual selection and the evolution of male pheromone glands in philanthine wasps (Hymenoptera, Crabronidae).

BACKGROUND: Sexual selection is thought to promote evolutionary changes and diversification. However, the impact of sexual selection in relation to other selective forces is difficult to evaluate. Male digger wasps of the tribe Philanthini (Hymenoptera, Philanthinae) scent mark territories to attract receptive females. Consequently, the organs for production and storage of the marking secretion, the mandibular gland (MG) and the postpharyngeal gland (PPG), are subject to sexual selection. In female Philanthini, these glands are most likely solely subject to natural selection and show very little morphological diversity. According to the hypothesis that sexual selection drives interspecific diversity, we predicted that the MG and PPG show higher interspecific variation in males than in females. Using histological methods, 3D-reconstructions, and multivariate statistical analysis of morphological characters, we conducted a comparative analysis of the MG and the PPG in males of 30 species of Philanthini and three species of the Cercerini and Aphilanthopsini, two related tribes within the Philanthinae. RESULTS: We found substantial interspecific diversity in gland morphology with regard to gland incidence, size, shape and the type of associated secretory cells. Overall there was a phylogenetic trend: Ensuing from the large MGs and small PPGs of male Cercerini and Aphilanthopsini, the size and complexity of the MG was reduced in male Philanthini, while their PPG became considerably enlarged, substantially more complex, and associated with an apparently novel type of secretory cells. In some clades of the Philanthini the MG was even lost and entirely replaced by the PPG. However, several species showed reversals of and exceptions from this trend. Head gland morphology was significantly more diverse among male than among female Philanthinae. CONCLUSION: Our results show considerable variation in male head glands including the loss of an entire gland system and the evolution of a novel kind of secretory cells, confirming the prediction that interspecific diversity in head gland morphology is higher in male than in female Philanthini. We discuss possible causes for the remarkable evolutionary changes in males and we conclude that this high diversity has been caused by sexual selection.

Phylogenetic relationships of Proboscoida Broch, 1910 (Cnidaria, Hydrozoa): Are traditional morphological diagnostic characters relevant for the delimitation of lineages at the species, genus, and family levels?

Overlapping variation of morphological characters can lead to misinterpretation in taxonomic diagnoses and the delimitation of different lineages. This is the case for hydrozoans that have traditionally been united in the family Campanulariidae, a group known for its wide morphological variation and complicated taxonomic history. In a recently proposed phylogenetic classification of leptothecate hydrozoans, this family was restricted to a more narrow sense while a larger clade containing most species traditionally classified in Campanulariidae, along with members of Bonneviellidae, was established as the suborder Proboscoida. We used molecular data to infer the phylogenetic relationships among campanulariids and assess the traditional classification of the family, as well as the new classification scheme for the group. The congruity and relevance of diagnostic characters were also evaluated. While mostly consistent with the new phylogenetic classification of Proboscoida, our increased taxon sampling resulted in some conflicts at the family level, specially regarding the monophyly of Clytiidae and Obeliidae. Considering the traditional classification, only Obeliidae is close to its original scope (as subfamily Obeliinae). At the genus level, Campanularia and Clytia are not monophyletic. Species with Obelia-like medusae do not form a monophyletic group, nor do species with fixed gonophores, indicating that these characters do not readily diagnose different genera. Finally, the species Orthopyxis integra, Clytia gracilis, and Obelia dichotoma are not monophyletic, suggesting that most of their current diagnostic characters are not informative for their delimitation. Several diagnostic characters in this group need to be reassessed, with emphasis on their variation, in order to have a consistent taxonomic and phylogenetic framework for the classification of campanulariid hydrozoans.

Thermal buffering capacity of the germination phenotype across the environmental envelope of the Cactaceae.

Recruitment from seeds is among the most vulnerable stage for plants as global temperatures change. While germination is the means by which the vast majority of the world's flora regenerate naturally, a framework for accurately predicting which species are at greatest risk of germination failure during environmental perturbation is lacking. Taking a physiological approach, we assess how one family, the Cactaceae, may respond to global temperature change based on the thermal buffering capacity of the germination phenotype. We selected 55 cactus species from the Americas, all geo-referenced seed collections, reflecting the broad environmental envelope of the family across 70° of latitude and 3700 m of altitude. We then generated empirical data of the thermal germination response from which we estimated the minimum (Tb ), optimum (To ) and ceiling (Tc ) temperature for germination and the thermal time (θ50 ) for each species based on the linearity of germination rate with temperature. Species with the highest Tb and lowest Tc germinated fastest, and the interspecific sensitivity of the germination rate to temperature, as assessed through θ50 , varied tenfold. A left-skewed asymmetry in the germination rate with temperature was relatively common but the unimodal pattern typical of crop species failed for nearly half of the species due to insensitivity to temperature change at To . For 32 fully characterized species, seed thermal parameters correlated strongly with the mean temperature of the wettest quarter of the seed collection sites. By projecting the mean temperature of the wettest quarter under two climate change scenarios, we predict under the least conservative scenario (+3.7°C) that 25% of cactus species will have reduced germination performance, whilst the remainder will have an efficiency gain, by the end of the 21st century.

Occurrence of sympatric charr groups, Salvelinus, Salmonidae, in the lakes of Kamchatka: a legacy of the last glaciations.

Six postglacial lakes were studied along both sides of the Kamchatka central mountain range, Russia. Pairs of local morphotypes of species of Arctic charrs, Salvelinus spp., have previously been described from the southernmost lakes while the fish fauna of the four northernmost lakes was studied here for the first time. Phenotypic data support the division of Kamchatkan lacustrine charrs into two groups according to the number of gill rakers and pyloric caeca, as well as snout-dorsal and snout-ventral distances (MANOVA, P < 0·001). These groups respectively correspond to phenotypes commonly referred to as Salvelinus malma and Salvelinus taranetzi. To clarify the identity of these groups, D-loop and cytochrome b (cytb) region sequences were analysed. Haplotype network analysis of mtDNA shows the salmonids inhabiting four lakes on the south and north are phylogenetically close to either Beringian S. malma or to S. taranetzi from the Chukotka and Kolyma River basins (the mean ± s.e. pairwise per cent sequence divergence is 0·006 ± 0·001). Phenotype-genotype discordance suggests that mitochondrial introgression between species has occurred in the two smallest lakes (<0·5 km2 ) in the central part of the peninsula. Identical haplotypes of D-loop and cytb regions were found for the populations of S. taranetzi from the most distant southern and northern lakes, indicating all lakes were colonized by both species simultaneously after the last glacial maximum. Salvelinus taranetzi may have colonized the Kamchatka peninsula from one or both of two different source regions: the Arctic Beringia and the northern coast of the Okhotsk Sea.

The Genetic Basis of Pheromone Evolution in Moths.

Moth sexual pheromones are widely studied as a fine-tuned system of intraspecific sexual communication that reinforces interspecific reproductive isolation. However, their evolution poses a dilemma: How can the female pheromone and male preference simultaneously change to create a new pattern of species-specific attraction? Solving this puzzle requires us to identify the genes underlying intraspecific variation in signals and responses and to understand the evolutionary mechanisms responsible for their interspecific divergence. Candidate gene approaches and functional analyses have yielded insights into large families of biosynthetic enzymes and pheromone receptors, although the factors controlling their expression remain largely unexplored. Intra- and interspecific crosses have provided tantalizing evidence of regulatory genes, although, to date, mapping resolution has been insufficient to identify them. Recent advances in high-throughput genome and transcriptome sequencing, together with established techniques, have great potential to help scientists identify the specific genetic changes underlying divergence and resolve the mystery of how moth sexual communication systems evolve.