Background: The morphological structures of organisms form tightly integrated but mutually independent character complexes (modules) linked through common development and function. Even though their abundance, diversity, and complex caste systems make camponotine ants ideal subjects to research developmental modularity and phenotypic integration, no studies investigating these phenomena have been conducted in this taxonomic group. This study attempts to identify and visualize integrated character complexes in 14 taxa from the genera Camponotus and Colobopsis using statistical analyses of morphometry. Results: The identified modules differ between castes: Minor workers have small heads and long extremities, while major workers have enlarged heads modified for defence, and short, thick appendages; extremities (legs and antennae) are strongly correlated in both worker castes. Gynes show weaker integration of extremities, but a strong correlation of mesosoma and eyes, and highly variable median ocellus size. Gynes infested by mermithid nematodes exhibit reduction of gyne-specific characters and altered patterns of phenotypic integration. Conclusion: The integrated character complexes described herein can largely be interpreted as functional, caste-specific modules related to behavioural ecology and task allocation within ant colonies. This modular nature of the body plan is hypothesized to facilitate the evolution of novel phenotypes and thus contributes to the tremendous evolutionary success of ants. The study of these modules can help to further elucidate the evolution and ontogeny of castes in camponotine ants, as well as the effects of parasite infestation on the phenotype.

Evolutionary theory predicts potential shifts between cooperative and uncooperative behaviour under fluctuating environmental conditions. This leads to unstable benefits to the partners and restricts the evolution of dependence. High dependence is usually found in those hosts in which vertically transmitted symbionts provide nutrients reliably. Here we study host dependence in the marine, giant colonial ciliate Zoothamnium niveum and its vertically transmitted, nutritional, thiotrophic symbiont from an unstable environment of degrading wood. Previously, we have shown that sulphidic conditions lead to high host fitness and oxic conditions to low fitness, but the fate of the symbiont has not been studied. We combine several experimental approaches to provide evidence for a sulphide-tolerant host with striking polyphenism involving two discrete morphs, a symbiotic and an aposymbiotic one. The two differ significantly in colony growth form and fitness. This polyphenism is triggered by chemical conditions and elicited by the symbiont's presence on the dispersing swarmer. We provide evidence of a single aposymbiotic morph found in nature. We propose that despite a high fitness loss when aposymbiotic, the ciliate has retained a facultative life style and may use the option to live without its symbiont to overcome spatial and temporal shortage of sulphide in nature.

We present a cellular automaton-based model for threshold behaviors in vertebrate digit patterning and polydactyly formation. The rules of the model follow classical reactor-diffusion algorithms. Yet it is not physical diffusion that is taken as the required natural agent but the propagation of cellular states, which can be represented by the same differential equations. The bistable cellular states in the model correspond to mesenchymal limb bud cells that can be either "on" or "off" for the cartilage differentiation pathway. Simulation runs demonstrate that reaction rate and cell number have the most decisive influence on the number of digit-like cell activation patterns. Threshold-based effects can generate supernumerary activation stripes via de novo condensation, stabilized bifurcation, and free floaters. All three behaviors are consistent with processes in natural polydactyly formation. It is argued that these effects are rooted in cell-based behaviors, not in gene regulation or globally diffusing morphogens. Our model suggests that the origin of discrete character states, such as individual digits, is a consequence of an additive cell state variable with a normal distribution that is transformed by a growth function with Turing behaviors into discontinuous phenotypic units. We discuss the application of this type of autopod patterning to the mutational, developmental, experimental, and evolutionary occurrences of polydactyly. The model provides a refinement of the previous Hemingway model for digit novelty and supports Turing type pattern formation in the vertebrate limb.

The drift of early development stages is an essential element of dispersal in many fish species. It is caused by a multitude of factors and is thus highly specific for each taxon and developmental stage. In this paper, we examined the drift of free embryos, larvae, and juveniles of percids and gobiids in a free-flowing stretch of the Austrian Danube. We assessed the drift density (DD) at different distances from the shore, described seasonal and diel patterns, and how size of drifting fish changed throughout the season. The seasonal patterns as well as the DDs were highly specific for each genus, while the diel patterns and changes in size of drifting fishes differed primarily at family level. In addition, we compared two opposed shorelines-a near-natural gravel bar and a rip-rap stabilized shore. The shores differed significantly and on both shores the DD of gobies was higher compared to percids. Among the Gobiidae, the invasive Neogobius species clearly dominated (99% of total gobiid catch) over the native tubenose goby Proterorhinus semilunaris. Percid DD was substantially higher on the near-natural shore, with Zingel and Sander as the most abundant genera.

Extremely divergent traits between males and females are often the result of different requirements and behaviours of the sexes and will evolve relatively rapidly under selection forces. Sexual dimorphism in Rhopalapion longirostre is predominately manifested in the length and structure of the rostrum. To estimate how sexual selection shapes mating success in this weevil we compared paired and unpaired individuals collected from three populations in Austria. The mating process in this species is complex and lengthy. Statistical analyses based on detailed observations of their mating behaviour revealed that matched pairs show functional affinities in body size. Females and males with larger elytra, as well as males with large overall body size, are favoured mating partners, while males that are too small have no mating success. This arrangement ensures copulation and consequently successful egg deposition. For efficient egg channel boring into the flower buds of the host plant, Alcea rosea, the extremely long female rostrum is a crucial tool. Natural selection promotes longer rostra in females whereas sexual selection favours the shorter rostra in males. The major evolutionary forces, natural and sexual selection, enhance the sexual dimorphism in this species.(c) 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115, 38-47.

No AccessZoologie im Hauch der Moderne: Vom Typus zum offenen SystemGerd B. Müller, Hans NemeschkalGerd B. Müller, Hans Nemeschkalhttps://doi.org/10.14220/9783737004152.355SectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinkedInRedditEmail About Previous chapter Next chapter FiguresReferencesRelatedDetails Download book coverVolume 004 1ISBN: 978-3-8471-0415-5 eISBN: 978-3-7370-0415-2HistoryPublished online:June 2015 PDF download

Point mutations in a cis-regulatory element of Sonic Hedgehog are frequently associated with preaxial polydactyly in humans, mice, and cats. The Hemingway mutant in the Maine Coon cat exhibits polyphenic effects of polydactyly that are not equally distributed. A statistical analysis of a comprehensive data base of Hemingway mutants reveals a biased and discontinuous distribution of extra digits. Further biases exist in the difference of effects in fore- versus hind-limbs and in left–right asymmetry. These non-equally distributed phenotypic effects cannot be explained by the point mutation alone. We propose a double mapping model, termed the Hemingway Model, to account for the biased distribution of supernumerary digits. The model is based on the random bistability of individual cells in the limb area affected by the mutation and on the application of the Central Limit Theorem. It proposes two kinds of mapping events that (a) transform a mutational effect of single additive changes into a continuous distribution, and (b) transform the continuous distribution into discrete character states via developmental threshold effects. The threshold widths for the occurrence of discrete extra digits are specified as units of standard deviations of the continuous variable. This makes it possible to specify the generation of empirical developmental variables (the liability of quantitative genetics) as a result of developmental parameters that give rise to biased morphological patterns and phenotypic novelty.

We studied habitat use and spatial distribution of Common Buzzards (Buteo buteo) in Schleswig-Holstein, northern Germany during the autumn of 2000, to assess the raptors' territoriality and its consequences for their use of space. For this purpose, we performed point counts covering an area of 20 km(2) during each of 20 continuous days and recorded 1537 observations of Common Buzzards and 109 of Rough-legged Hawks (Boles logopus). Applying multivariate Poisson regression combined with randomization tests, we detected that Common Buzzards showed a preference for areas with a larger distance from nesting sites of the previous spring (P = 0.019; n = 290 grid units of 250 X 250 m in all three cases), a high density of vole holes (P < 0.001), and a low density of perch-sites (P = 0.005). These preferences regarding vole holes and perches were also valid when only grid units far from the nesting sites were considered. Indirectly, the buzzards were also affected by the amount of grassland and by the amount of dry land, as these parameters were strongly related to vole-hole density. The distributions of the sympatric wintering species Rough-legged Hawk and Common Buzzard did not affect each other. Our study indicated that territorial sedentary, breeding pairs displaced nonbreeders and wintering birds into suboptimal habitats, and it offers valuable clues on the constraints for Common Buzzards in areas where they occur in high abundance during late autumn and winter.

Probst R., Nemeschkal H.L., McGrady M., Tucakov M. & Szép T. 2011. Aerial hunting techniques and predation success of Hobbies Falco subbuteo on Sand Martin Riparia riparia at breeding colonies. Ardea 99: 9–16.We analysed 291 attacks by 15 male Hobbies Falco subbuteo at 13 different Sand Martin Riparia riparia colonies in Austria, Hungary, and Serbia in 2004 and 2005. We predicted that the choice of escape strategy would be contextdependent and related to the condition and age of swallows and relative position and flight characteristics of both predator and prey. We predicted that swallows would be unable to escape falcons in a level chase and would not seek cover. We predicted that falcons would be more successful when juveniles were present. Hunting success rates were higher during the swallows' post-fledging period, probably because of the weaker flight performance of juveniles. Invariably, adult swallows tried to outclimb falcons, while probable juveniles also tried to escape to cover. Hobbies most often attacked adult swallows by a fast approach from great heights and distances. In contrast, in the post-fledging period, when juveniles were available, low horizontal attacks and long climbing chases were common. In doing so, Hobbies at times prevented juvenile swallows from taking cover and were, in turn, sometimes able to outclimb and capture them. Significantly more attacks were abandoned during the post-fledging period. Sand Martins were unable to escape Hobbies in a level chase. Individual male Hobbies showed no difference in hunting success, maybe because all were experienced. The number of Sand Martins present at the time of attack did not influence hunting success. The results are discussed in the light of the anti-predator strategies of animals living in groups.

Extreme sexually dimorphic phenotypes are frequently attributed to strong sexual selection but they can also arise as a consequence of different ecological demands. The evolutionary emergence of elongated rostra was a key event in the adaptive radiation of weevils. Exaggerated female rostra evolved in numerous weevil taxa, enabling females to bore long channels for egg deposition into various parts of host plants. The investigated ecological scenario involves three species of brentid weevils, all associated with the same host plant, Alcea rosea. The present study reveals that: (1) Rhopalapion longirostre bores egg channels into the buds, and the female rostrum is twice as long and its surface is smoother than in the male; (2) Alocentron curvirostre and Aspidapion validum live on the same host plant but use the stems for egg deposition; in these species, female rostra are not exaggerated; (3) the females of all three species possess a stronger mandible musculature than males; (4) the elongated female snout of R. longirostre is a response to the requirements of boring egg channels of maximal depth into the buds of the host plant; and (5) female muscle strength is an adaptation to boring into hard plant tissues, irrespective of rostrum length. (C) 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104, 642-660.

Multivariate statistics (principal components analysis, path analysis) were used to investigate fitness compo- nents of the interactions between the weevil Rhopalapion longirostre (Olivier, 1807), Apionidae, Coleoptera and its host plant Alcea rosea (Linnaeus, 1758), Malvaceae. We focused on the activities of the larvae such as the choice of seeds for consumption, the preparation of seed chambers as a site for pupation, as well as the construction of escape holes through which the adults later emerge. The analyses revealed that the optimal conditions for successful development of the weevils depended on the availabil- ity of seed capsules characterized by a high number of well developed seeds, few undeveloped and few spoiled seeds. The high number of larvae, pupae and not emerged adults found in the seed capsules corresponds with the successful emergence of adults. Egg deposition by the females in appropriate flower buds of the host plant, together with larval con- tribution to overall reproductive success are important fitness components in the life cycle of the weevil. The reproduc- tive success of the plant is partly guaranteed by a high number of seed chambers, many well developed seeds, many not infested seeds, and few undeveloped seeds. Furthermore, the extended blooming period of the host plant serves as an es- cape strategy by developing buds early or late in the season that cannot become entangled in the life cycle of R. lon- girostre.

Effects of initial size on the growth and survival of a freshwater fish, Chondrostoma nasus, were tested in a field survey, where individually tagged larvae were introduced into a potential nursery habitat. Characteristics of individual daily growth trajectories were utilized as a basis to explain growth, as well as survival patterns, in relation to ontogeny. Initial size only affected growth rates during the larval phase. Survival patterns could not be explained solely based on size-selective mortality processes because prey-predator interactions played a major role as well. This is confirmed by the Lande-Arnold selection model because directional, as well as stabilizing gradients, showed significant values. Thus, for the 0+ year freshwater fish, inherited size-specific effects were a significant advantage for growth performance and survival in early ontogeny. As fish grew older, however, other effects such as compensatory growth and prey-predator interactions apparently gained in importance.

The Neotropical genus Heliconius (Nymphalidae) is unique among butterflies for its pollen-feeding behaviour. With the application of saliva, they extract amino acids from pollen grains on the outside of the proboscis. We predicted that the salivary glands of pollen-feeding Heliconiinae would show adaptations to this derived feeding behaviour. A biometrical analysis of the salivary glands revealed that pollen-feeding butterflies of the genus Heliconius have disproportionately longer and more voluminous salivary glands than nonpollen-feeding Nymphalidae. The first two components in the principal component analysis explained approximately 95% of the total variance. The size-dependent factor score coefficients of body length and salivary gland parameters were predominately represented on axis 1. They significantly discriminated pollen-feeding from nonpollen-feeding heliconiines on that axis. Factor score coefficients for the volume of the secretory region of the salivary glands separated heliconiines from the outgroup species. The detailed biometrical analysis of salivary glands features thus provides strong evidence that the secretory regions of the salivary glands are larger in pollen-feeding butterflies. We concluded that pollen feeding is associated with a high production of salivary fluid. (C) 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 604-612.

The permanent meiobenthic community associated with aggregations of the tubeworm Riftia pachyptila was characterized at 2 different hydrothermal vent sites, Tica and Riftia Field, on the East Pacific Rise near 9 degrees 50'N. The maximum effluent temperatures were similar at both sites, but the chemistry of the hydrothermal fluids differed between sites. The abundance of meiobenthos was very low in 5 out of 6 samples (<61 ind. 10 cm(-2)) and was higher at Tica (20 to 976 ind. 10 cm(-2)) than at Riftia Field (< 1 to 12 ind. 10 cm(-2)). Meiobenthos abundance was positively correlated with the volume of sediment within the tubeworm aggregations. Sediment consisted mainly of particulate organic material and contained only a few mineral grains. A total of 33 meiobenthic species (15 of them new to science) was identified, comprising nematodes, copepods, ostracods, tanaidaceans, and foraminiferans. The meiobenthic fauna contributed a third to the total species richness in the benthic community associated with these tubeworm aggregations. There were 19 meiobenthic species shared between the 2 sites. The majority of meiobenthic species were first-order primary consumers. The most abundant taxa were nematodes and copepods, and other taxa were rare at both sites. Nematodes numerically dominated the community at Tica, while no clear dominance of a higher taxon could be detected at Riftia Field. Species richness was similar at both sites, whereas Shannon-Wiener diversity index and Pielou's evenness index were higher at Riftia Field. Due to the differences in the relative abundance of some species and unique occurrence of others at each site, the meiobenthic communities from the 2 different sites had an average Bray-Curtis dissimilarity of almost 70%.

The meiobenthic nematode community of three different vent sites at the East Pacific Rise was studied in order to determine whether the abundance, species richness, diversity and trophic structure were similar. The sites Tica and Riftia Field were dominated by the tubeworm, Riftia pachyptila, and the Buckfield site was dominated by the mussel Bathymodiolus thermophilus. The nematode communities of all three sites were low in abundance (< 1 up to 46 ind. 10 cm(-2)), except one sample from Tica with almost 1000 ind. 10 cm(-2). The communities at all sites consisted entirely of primary consumers, mostly deposit feeders. Species richness and Shannon-Wiener diversity indices were low and similar at both tubeworm sites and slightly but significantly higher at the mussel site. Multivariate analysis revealed that the species dissimilarity among the three sites was greater than 50%, indicating distinct communities at each site.

Deep-sea hydrothermal vents occur along the mid-ocean ridges and back-arc basins around the globe. There are very few community analyses of vent meiobenthos. The central objectives of this study were to identify and quantify for the first time the entire metazoan meiobenthic community associated with mussel aggregations of Bathymodiolus thermophilus Kenk and Wilson, 1985 from the EPR, 11°N and of Bathymodiolus puteoserpentis Cosel et al., 1994 from the Mid-Atlantic Ridge (MAR), 23°N. Using a quantitative sampling method, abundance, biomass, sex ratio, species richness, diversity, evenness, and trophic structure were studied based on three samples from each site. Meiobenthic abundance in each sample was unexpectedly low, but similar between sites. The community was composed of nematodes, copepods, ostracods, and mites, with a total of 24 species at EPR vents, and 15 species at MAR vents. While most copepod species were vent endemics within the family Dirivultidae, nematodes and harpacticoid copepods belonged to generalist genera, which occur at a variety of habitats and are not restricted to hydrothermal vents or the deep sea. The meiobenthos of hydrothermal-vent mussel beds constitutes a unique community unlike those of other sulfidic habitats, including the thiobios of shallow-water sediments and the meiobenthos of deep-sea, cold-seep sediments. The trophic structure was dominated by primary consumers, mainly deposit feeders, followed by parasites. Predatory meiofaunal species were absent.

We present a phylogenetic perspective on morphological and molecular characters and character complexes and their properties at different hierarchical levels, using both examples from literature and case studies in carduelid finches and pigeons. Phylogenetic hypotheses inferred from both molecular (cytochrome-b) and morphological characters (plumage ornamentations), and combined analyses in carduelids, indicate that in both datasets corresponding patterns occur at particular nodes and systematic levels. A new method is introduced to partition and quantify correlation in cladogenetic, anagenetic and environmen- tal signal, to estimate by their degree of similarity the underlying factors producing that correspondence.