Does developmental acclimatization reduce the susceptibility to predation in newt larvae?

Many organisms respond to the heterogeneity of abiotic environmental conditions by plastic modifications of their phenotypes (acclimation or acclimatization). Despite considerable research efforts in this area, the beneficial (adaptive) effect of acclimation or acclimatization is still debated. We examined whether the development of newt larvae (Ichthyosaura alpestris) under different natural light and thermal conditions subsequently altered their susceptibility to predation in sun‐exposed versus shaded tanks in nature. During predation trials in various light and temperature conditions, newt larvae that developed in sun‐exposed warmer tanks consistently suffered from higher predation by dragonfly nymphs (Aeshna cyanea) compared to larvae from shaded or colder tanks. We conclude that higher sun exposure during embryonic and larval development negatively affects antipredator performance even in sun‐exposed tanks: this result is inconsistent with the beneficial acclimation hypothesis. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

A further look at the 1858 Wallace–Darwin mail delivery question

Recent investigations have led to a conclusion that Alfred Russel Wallace probably mailed his ‘Ternate’ paper on natural selection to Darwin 1 month later than some have assumed, thus freeing Darwin from possible accusations of plagiarism. Further examination of the question suggests that this conclusion is premature because the evidence in favour of the later mailing date appears to be weaker than first considered. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Unexpectedly low frequencies of diploid males in an inbreeding parasitoid with complementary sex determination

In hymenopterans with single locus complementary sex determination, sex depends on the genotype at one polymorphic locus. Haploids are always male, while diploids are female when heterozygous and male when homozygous at the sex‐determining locus. Brothers and sisters have a 50% chance of sharing a sex allele (i.e. of being ‘matched’), and hence half of all sibling matings are expected to produce diploid males at the expense of females. Nevertheless, observed frequencies of diploid males are often lower than predicted, as diploid males may succumb to pre‐imaginal mortality, or because unmatched mates or sperm enjoy a competitive advantage. We counted diploid males in broods of the parasitoid wasp Cotesia glomerata sampled in the field, and in broods produced through controlled laboratory crosses. Consistently, the frequency of diploid males fell below expectations based upon the estimated occurrence of sibling mating. In the staged broods with diploid males, females made up a disproportionately large share of the diploids. Broods with and without diploid males were of similar size. Hence, the shortage of diploid males cannot be accounted for by differential pre‐imaginal mortality alone. Instead, we postulate the existence of a mechanism that leads to preferential fertilization of eggs by sperm bearing unmatched alleles. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Host range evolution in a selected group of osmiine bees (Hymenoptera: Megachilidae): the Boraginaceae‐Fabaceae paradox

Bees are extraordinarily diverse with respect to host plant choice and adaptation. Recent findings suggest that bee host range might be largely governed by evolutionary constraints related to pollen digestion or flower recognition and handling. In the present study, we applied phylogenetic inference to investigate whether such constraints underlie host plant choice in bees of the Annosmia‐Hoplitis group (Megachilidae) and to what extent these bees have evolved specialized adaptations for pollen collection. We demonstrate that most pollen specialist species exclusively exploit either Boraginaceae or Fabaceae, whereas all pollen generalists harvest pollen from both Boraginaceae and Fabaceae. The counterintuitive affinity towards these two plant families, which are neither closely related nor share similar flower morphologies, demonstrates that pollen host choice is considerably constrained in this group of bees. We hypothesize that this Boraginaceae‐Fabaceae paradox might be the result of (1) similar secondary metabolites in the pollen of both families; (2) metabolites that can be detoxified by the same physiological tools; or (3) similar pollen nutrient composition. Contrary to the widely held belief that specialized adaptations for pollen collection are rare among bees, such adaptations are common in the Annosmia‐Hoplitis bees, where they have evolved several times independently to exploit flowers of widely different morphologies. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Size and sex matter: reproductive biology and determinants of offspring survival in Gazella marica

For prey, many behavioural traits are constrained by the risk of predation. Therefore, shifts between warning and cryptic coloration have been suggested to result in parallel changes in several behaviours. In the present study, we tested whether changes in chromatic contrast among eight populations of the strawberry poison‐dart frog, Dendrobates pumilio, co‐vary with behaviour, as expected if selection is imposed by predators relying on visual detection of prey. These eight populations are geographically isolated on different island in the Bocas del Toro region of Panama and have recently diverged morphologically and genetically. We found that aggression and explorative behaviour were strongly correlated and also that males tended to be more aggressive and explorative if they belonged to populations with conspicuously coloured individuals. We discuss how evolutionary switches between predator avoidance strategies and associated behavioural divergence between populations may affect reproductive isolation. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

At the north-eastern extremity: variation in <Emphasis Type="Italic">Cepaea nemoralis</Emphasis> around Gdańsk,northern Poland

Variation in the shell colour and banding polymorphism in the land snail Cepaea nemoralis was studied in 260 populations in the region of Gdańsk, northern Poland. Unlike in other regions of Poland, many populations contain brown shells. Populations from shaded habitats have higher frequencies of brown than those from open and intermediate habitats, largely at the expense of yellow shells. Nearly all brown shells are also unbanded. Apart from this disequilibrium, banding morphs among yellow and pink shells show no relationship to habitat. There are no broad geographical trends in morph-frequencies, but there are very strong correlations among populations very close together, revealed both by pairwise analysis and Moran’s I. Principal Component Analyses show that these correlations relate to overall genetic similarity at the loci involved. The populations are at the north-eastern limits of the species’ range; habitats are mostly anthropogenic, and comparisons with studies in two urban areas (Wrocław, SW Poland, and Sheffield, central England) suggest that the patterns of variation seen are a product of human transport of propagules followed by local dispersal. The effect of habitat here is much less marked than in regions much further west, but it indicates that natural selection has occurred.     

Exploring the dichotomy between animals building using self‐secreted materials and using materials collected from the environment

The collection and the secretion of building materials are two radically different processes: one behavioural; the other physiological. This article examines whether selection pressures operating upon these have led to quite different outcomes or whether priorities common to both have led to parallel solutions. The article also examines selection pressures peculiar to secreted materials. It explores the influence of diet on the biochemistry of the secreted material and the evolutionary consequences for social species of the allocation of the costs of secreting the building material. Conclusions in some of these areas are hindered by a lack of evidence, but this also indicates opportunities for future research. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Temporal and geographical variation in skull size of the red fox (Vulpes vulpes) and the Eurasian badger (Meles meles) in Austria

Using museum material, we studied temporal changes in skull size of 185 red foxes (Vulpes vulpes Linnaeus, 1758) and 71 Eurasian badgers (Meles meles Linnaeus, 1758) collected in Austria between 1866 and 2007. Four measurements were taken and combined into principal components by means of a principal components analysis. Akaike's information criterion models indicated that skull size of the red fox and the Eurasian badger is positively related to the year of collection and negatively to altitude but not to latitude or longitude. However, for the Eurasian badger, the relationship between skull size and year is only on the verge of significance. We suggest that the increase in skull size with year is a result of improved food availability during the 20th Century from man‐made resources such as agricultural produce and garbage, and the decrease in skull size with altitude is possibly the result of a parallel decrease in primary productivity. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Rapid evolution in unstable habitats: a success story of the polymorphic land snail Cepaea nemoralis (Gastropoda: Pulmonata)

The present study reports on a natural experiment with twelve replicates in which rapid, predictable and consistent divergence of Cepaea nemoralis populations occurred in response to repeated selection gradient of adjacent open and shaded habitats. Because the frequencies of various genetically‐based phenotypes varied widely among surveyed populations, and there was a large overlap between habitat types, no overall association with habitat was apparent. In paired comparisons, however, significant changes were consistently towards higher frequencies of light morphs in the open than corresponding shaded habitats, and this result is attributable to natural selection. This shows that the knowledge of the genetic composition of reference populations is often essential for discerning selection from random processes. At each site, a different morph combination contributed to the divergence of populations, indicating that there are many genetic solutions to similar ecological problems; this likely enhances the maintenance of high levels of polymorphism. Adaptation of populations occurred in contemporary time and was fast. In one case where it was possible to follow changes, significant shifts in morph frequencies occurred within just two snail generations (selection coefficients of 0.404 and 0.518). High evolvability may be one of the factors contributing to the ecological success of Cepaea nemoralis. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 251–262.     

AFLP analysis shows high incongruence between genetic differentiation and morphology‐based taxonomy in a widely distributed tortoise

Morphology has traditionally been used to diagnose the taxa of various taxonomic ranks. However, there is growing evidence that morphology is not always able to reveal cryptic taxa, and that pronounced morphological variation could reflect phenotypic plasticity rather than evolutionary divergence. Spur‐thighed tortoises (the Testudo graeca complex), distributed in the western Palaearctic region, are characterized by high morphological variability and complicated taxonomy, which are under debate. Previous molecular studies using mainly mitochondrial DNA (mtDNA) sequences have revealed incongruence between genetic differentiation and morphology‐based taxonomy, suggesting that morphological variability is the result of phenotypic plasticity and stabilizing selection, which masks the true genealogies. In the present study, we used a range‐wide sampling and nuclear Amplified fragment length polymorphism (AFLP) markers to investigate genetic differentiation within the T. graeca complex. We found that spur‐thighed tortoises are differentiated into four geographically well‐defined AFLP groups: Balkans–Middle Eastern, western Mediterranean, Caucasian and central‐eastern Iranian. Compared with the distribution of mtDNA lineages, the groups are largely concordant, although the AFLP markers are less sensitive and distinguish fewer groups than do mtDNA sequences. The AFLP groups show an allopatric or parapatric distribution. The AFLP differentiation conflicts with the previously proposed morphology‐based taxonomy of the complex, suggesting that local adaptation to different environmental conditions may have led to the great extent of morphological variation within the same lineages. We propose a re‐evaluation of the taxa that were confirmed genetically using a thorough morphological analysis corrected for phenotypic plasticity. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Length–mass allometry in snakes

Body size and body shape are tightly related to an animal's physiology, ecology and life history, and, as such, play a major role in understanding ecological and evolutionary phenomena. Because organisms have different shapes, only a uniform proxy of size, such as mass, may be suitable for comparisons between taxa. Unfortunately, snake masses are rarely reported in the literature. On the basis of 423 species of snakes in 10 families, we developed clade‐specific equations for the estimation of snake masses from snout–vent lengths and total lengths. We found that snout–vent lengths predict masses better than total lengths. By examining the effects of phylogeny, as well as ecological and life history traits on the relationship between mass and length, we found that viviparous species are heavier than oviparous species, and diurnal species are heavier than nocturnal species. Furthermore, microhabitat preferences profoundly influence body shape: arboreal snakes are lighter than terrestrial snakes, whereas aquatic snakes are heavier than terrestrial snakes of a similar length. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Steneosaurus edwardsi (Thalattosuchia: Teleosauridae), the largest known crocodylomorph of the Middle Jurassic

Teleosaurids were a clade of marine crocodylomorphs that were globally distributed during the Jurassic Period. They evolved a wide range of body sizes, from small (～2–3 m) to very large (> 9 m). Until now, the largest known Middle Jurassic teleosaurid was ‘Steneosaurus’ obtusidens, from the Oxford Clay Formation of the UK. Here, we re‐examine a very large Oxford Clay specimen (ilium, ischium, and femur) that had been tentatively attributed to ‘S.’ obtusidens. Based on comparative anatomical study with the ‘S.’ obtusidens holotype and referred specimens of Steneosaurus edwardsi and Steneosaurus leedsi, we conclude that this very large individual actually pertains to S. edwardsi. Based on comparisons with the Machimosaurus mosae neotype (which has a complete femur and skeleton), we estimate a total length in excess of 7 m for this large S. edwardsi individual, making it the largest known Middle Jurassic teleosaurid. Therefore, along with the closely related genus Machimosaurus, this clade of large‐bodied Middle–Late Jurassic teleosaurids were the largest species during the first 100 million years of crocodylomorph evolution. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, ●● , ●●–●●.     

Transgressive segregation in a behavioural trait? Explorative strategies in two house mouse subspecies and their hybrids

Hybrid zones between genetically diverged populations are widespread among animals and plants. Their dynamics usually depend on selection against admixture and dispersal of parental forms in the zone. Although indirect estimates of selection have been the target of many studies, dispersal has been neglected. In this study we carried out open field experiments to test whether males of two house mouse subspecies, Mus musculus musculus and Mus musculus domesticus, differ in their propensity to disperse and in their character of exploration. We tested wild‐caught males and males of two wild‐derived inbred strains. In addition, we examined reciprocal F₁ crosses to test the prediction that these hybrids display intermediate behaviours. We revealed that M. m. musculus males were less hesitant to enter the experimental arena than were M. m. domesticus males, but once inside the arena their movements were more timid. F₁ males differed from both parental strains, with longer latencies to enter the arena, but explored the arena in a similar fashion as the M. m. domesticus males, thus displaying transgressive behavioural phenotypes. These results contribute to our knowledge of behavioural divergence between the mouse subspecies, and add a new facet to the study of speciation. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●●, ●●–●●.     

A comparison of the wood anatomy of 11 species from two cerrado habitats (cerrado s.s. and adjacent gallery forest)

A comparative study of the secondary xylem (wood) anatomy of 11 species (38 specimens) occurring in cerrado s.s. and the adjacent gallery forest (both cerrado s.l. habitat) was made with the aim of identifying the anatomical characteristics of ecological value and correlating them with the environmental conditions. The anatomical features that vary, in general, between the two habitats are: growth ring distinctness (well or poorly defined); tyloses and deposits (more abundant in cerrado specimens); gelatinous fibres (more evident in cerrado specimens and in different patterns between habitats); variation in paratracheal and banded parenchyma (more abundant in cerrado); and more cells per parenchyma strand in cerrado. In general, gallery forest specimens have wider vessels, fewer vessels per square millimetre and larger intervessel pits, indicating more efficient water conduction, whereas cerrado s.s. specimens are the opposite, with low vulnerability and mesomorphy indices, demonstrating greater safety under conditions of water stress. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, ?? , ??–??.     

The Scotch broom,Cytisus scoparius (Fabaceae), a paradox in Denmark – an invasive plant or endangered native species?

Scotch broom, Cytisus scoparius, spreads rapidly in parts of Denmark and is considered an invasive species by some authors. However, the species has been present in the Danish flora for centuries and is therefore considered native to Denmark. In the present study we explore whether Danish Scotch broom consists of one or two gene pools with potential differences in phenotype and invasiveness. One plastid and five nuclear microsatellite markers were used to reveal potential substructuring of Danish Scotch broom. Nine populations were included representing populations exhibiting invasive behaviour and populations showing non‐invasive behaviour. An Italian population was used as reference. Bayesian analysis based on genetic markers indicated that the sampled populations form two distinct gene pools, and this pattern was supported by neighbour‐joining trees. Measurements of height and width of the analysed plants showed that the two gene pools correspond to populations exhibiting either a horizontal habit and non‐invasive behaviour or an erect habit and, in some cases, invasive behaviour. The Italian population clustered with the erect ones. We discuss the origin and taxonomic status of the two gene pools and conclude that Danish horizontal Scotch broom should be given a formal taxonomic status in order to initiate conservation activities for its protection. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Physiological change in an insular lizard population confirms the reversed island syndrome

Unpredictable environmental conditions and highly fluctuating population densities are believed to have produced a ‘reversed island syndrome’ (RIS) in an insular population of the Wall lizard on Licosa Islet, Italy. Several of the physiological, behavioural, and life‐history changes that constitute the RIS could result from positive selection on increased activity of melanocortins. For example, increased levels of α‐melanocyte‐stimulating hormone (MSH) should lead to increased investment in reproduction and increased immunocompetence in the island population. We tested the crucial assumption of this idea that plasma levels of α‐MSH in Licosa Islet lizards are elevated compared to those of the mainland relatives. We also tested for differences in reproductive effort between populations, by measuring plasma levels of 5‐α‐dihydrotestosterone in males and clutch mass in females. In addition, we assessed ectoparasite load as an indicator for the lizards’ resistance to environmental stress. In agreement with the RIS, we found that insular lizards exhibit higher α‐MSH levels, allocate more energy to reproduction, and have a reduced ectoparasite load compared to the nearest mainland population. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Phylogenetic systematics of Erythronium (Liliaceae): morphological and molecular analyses

For a nearly complete set of species of Erythronium (Liliaceae), we examined two plastid loci (the rps16 intron and the 5′ trnK intron, excluding the matK exon), one nuclear locus (nrITS) and morphology to evaluate species relationships and that of Erythronium to Amana, the putatively most closely allied genus. A matrix of morphological characters was developed through observation of around 900 living and herbarium specimens; evolution of these was examined using character optimization on the combined (total‐evidence) tree. Parsimony methods were used to examine the morphological and molecular data sets produced, both separately and in combination, with Bayesian methods also used on the molecular data sets. These established that the genus is probably sister to Amana (although most analyses placed Amana inside Erythronium) and that Tulipa is sister to the pair of Erythronium and Amana. Within Erythronium, there are three strongly supported geographically distinct clades: (1) Eurasian and (2) eastern and (3) western North American. Separation of species in these three clades is less clear, particularly among the western North American taxa. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, ●●, ●●–●●.     

Size‐dependent insect flight energetics at different sugar supplies

Under most circumstances, large body size confers a higher fitness and is positively selected, whereas selection against large size is empirically poorly documented. Physiologically, according to the ¾ power law, larger animals have lower relative but higher absolute energy demands, such that large body size may become disadvantageous, particularly under fast locomotion in food‐limited environments. After a period of initial feeding on different sugar concentrations, we investigated size‐dependent energy content (reserves) at baseline and of females unflown (i.e. resting) or flown for 18 h in two (replicate) insect species: the yellow dung fly Scathophaga stercoraria and the yellow fever mosquito Aedes aegypti. Tethered adults of various sizes were tested in a flight mill. In both species, teneral glycogen, sugar, and lipid content increased with sugar availability, and isometrically or even hyper‐allometrically (slope > 1) with body size. Activity treatment also revealed the expected consumption effects. Both species increased their flight distance with sugar supply, although only larger mosquitoes flew longer. Crucially, larger females of both species disproportionately exhausted more glycogen and sugars (but not lipid) during flight. The mosquitoes appeared to adjust their flight more finely to their size‐dependent energy reserves at all sugar availabilities, whereas, in the dung flies, size‐dependent energy demands were detectable only with a low but not with an overly high sugar supply. Although we found a greater absolute and relative locomotory energy demand for the larger flies, which is in agreement with interspecific patterns in insects, this was (more than) compensated by their greater baseline energy reserves, resulting in the greater net flying capacity of larger individuals. Consequently, we found no evidence for energetic mechanisms limiting the performance of large flying insects under food limitation. The differences between the two species presumably relate to mosquitoes inherently being long distance flyers and dung flies being short distance flyers. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Once a land of big wild rivers: specialism is context‐dependent for riparian snails (Pulmonata: Valloniidae) in central Europe

Specialist species may be perceived as such because of their narrow ecological requirements, but this may be context‐dependent. The genus Vallonia (Gastropoda Pulmonata: Valloniidae) includes widespread generalist species and also two specialists endemic to Central Europe: Vallonia suevica, restricted to warm, wet meadows and riverbanks subject to seasonal flooding; and Vallonia declivis, living only in wet to humid meadows, riverbanks, and reedbeds. Both have experienced dramatic declines; as is the case with many land snails, their global conservation status has been underestimated: these species are Critically Endangered. Other congenerics are probably dispersed by birds. In contrast, the distributions of these meadow specialists appear to be the outcome of their strictly riparian habitat coupled with dispersal by fish. Thus, they have tracked drainage changes through the Pleistocene from their origin in the floodplain uplands of the Danube biodiversity hotspot in the Pliocene. Natural dispersal mechanisms have been disrupted, and riparian and river ecosystems have been destroyed throughout Europe. This has led big‐river specialist molluscs and their associated fishes to the brink of extinction. The notion of specialism thus depends on the ecological context; it is useful to stress their non‐invasive character, current restriction to scarce habitats, and evolution under quite different conditions. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, ●● , ●●–●●.