bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sexual size dimorphism and selection in the wild in the waterstrider Aquarius remigis: Body size, components of body size and male mating success
Authors: Preziosi R. F. , Fairbairn D. J. 
Published: December 2004

AbstractSexual size dimorphism is assumed to be adaptive and is expected to evolve in response to a difference in the net selection pressures on the sexes. Although a demonstration of sexual selection is neither necessary nor sufficient to explain the evolution of sexual size dimorphism, sexual selection is generally assumed to be a major evolutionary force. If contemporary sexual selection is important in the evolution and maintenance of sexual size dimorphism then we expect to see concordance between patterns of sexual selection and patterns of sexual dimorphism. We examined sexual selection in the wild, acting on male body size, and components of body size, in the waterstrider Aquarius remigis, as part of a long term study examining net selection pressures on the two sexes in this species. Selection was estimated on both a daily and annual basis. Since our measure of fitness (mating success) was behavioral, we estimated reliabilities to determine if males perform consistently. Reliabilities were measured as ϰ statistics and range from fair to perfect agreement with substantial agreement overall. We found significant univariate sexual selection favoring larger total length in the first year of our study but not in the second. Multivariate analysis of components of body size revealed that sexual selection for larger males was not acting directly on total length but on genital length. Sexual selection for larger male body size was opposed by direct selection favoring smaller midfemoral lengths. While males of this species are smaller than females, they have longer genital segments and wider forefemora. Patterns of contemporary sexual selection and sexual size dimorphism agree only for genital length. For total length, and all other components of body size examined, contemporary sexual selection was either nonsignificant or opposed the pattern of size dimporhism. Thus, while the net pressures of contemporary selection for the species may still act to maintain sexual size dimorphism, sexual selection alone does not.
Evolutionary responses of Drosophila melanogaster life history to differences in larval density
Authors: Roper C. , Pignatelli P. , Partridge L. 
Published: December 2004

AbstractThe study examined the effects of evolution at two different larval densities on pre‐adult and adult fitness traits. Five replicate selection lines each were cultured at either 50 or 150 larvae per vial, avoiding selection on development time, age at breeding or for adaptation to adult density, one or more of which factors has been a confounding variable in previous studies. Low density selection lines evolved extended development times at both growth densities. The extended development times were associated with greater adult body size at the lower growth density only, and particularly in females. The lines did not differ significantly in larval competitive ability at either growth density. At neither growth density did the early adult fertility of females or the lifespan of either sex differ between the lines from the two selection regimes, but at the lower growth density the late fertility of low density line females was significantly enhanced. The results suggest that larval density does have important effects on the expression and resolution of life history trade‐offs in Drosophila melanogaster, but that these may be somewhat different from those reported in previous studies.
A meta‐analysis of the heritability of developmental stability
Authors: Møller A. P. , Thornhill R. 
Published: December 2004

AbstractThe existence of additive genetic variance in developmental stability has important implications for our understanding of morphological variation. The heritability of individual fluctuating asymmetry and other measures of developmental stability have frequently been estimated from parent‐offspring regressions, sib analyses, or from selection experiments. Here we review by meta‐analysis published estimates of the heritability of developmental stability, mainly the degree of individual fluctuating asymmetry in morphological characters. The overall mean effect size of heritabilities of individual fluctuating asymmetry was 0.19 from 34 studies of 17 species differing highly significantly from zero (P < 0.0001). The mean heritability for 14 species was 0.27. This indicates that there is a significant additive genetic component to developmental stability. Effect size was larger for selection experiments than for studies based on parent‐offspring regression or sib analyses, implying that genetic estimates were unbiased by maternal or common environment effects. Additive genetic coefficients of variation for individual fluctuating asymmetry were considerably higher than those for character size per se. Developmental stability may be significantly heritable either because of strong directional selection, or fluctuating selection regimes which prevent populations from achieving a high degree of developmental stability to current environmental and genetic conditions.
On the evolution of heavy‐metal tolerant populations in Armeria maritima: evidence from allozyme variation and reproductive barriers
Authors: Vekemans X. , Lefèbvre C. 
Published: December 2004

AbstractThe process of ecological differentiation leading to the evolution of heavy‐metal tolerant populations in Armeria maritima was studied by comparing population genetic structure and pattern of gene flow between populations growing on heavy‐metal contaminated against non‐contaminated sites using allozyme markers. In addition the evolution of reproductive isolation among populations was studied by measuring pollen fertility in interpopulational hybrids. The allozyme data suggested that in A. maritima multiple independent evolutionary origins of heavy‐metal tolerant populations have occurred in the absence of strong genetic bottlenecks. The pattern of gene flow among populations was consistent with the model of isolation by distance with considerable gene flow between neighbor populations, and no reduction of gene flow between tolerant and non‐tolerant populations. Hence it appears that substantial gene flow has not hampered genetic differentiation, probably because of the high selection pressure for heavy‐metal tolerance. The pattern of reproductive isolation among populations suggests that evolution of heavy‐metal tolerant populations has not triggered the development of reproductive barriers against non‐tolerant populations. However, partial reproductive isolation has occurred under geographic separation.
Performance of two monophagous leaf feeding beetles (Coleoptera: Chrysomelidae) on each other's host plant: Do intrinsic factors determine host plant specialization?
Authors: Keese M. C. 
Published: December 2004

AbstractThere has been much recent debate on whether physiological tradeoffs in performance across hosts or ecological factors such as predation are the primary determinants of host plant specialization in plant‐herbivore interactions. This paper examines the relative role of intrinsic behavioral and physiological factors in host specialization of two species of leaf‐feeding beetles (Coleoptera: Chrysomelidae). Ophraella notulata and Ophraella slobodkini are sister taxa that feed exclusively on the asteraceous plants Iva frutescens and Ambrosia artemisiifolia, respectively. Ambrosia is the ancestral host plant for this pair of beetles. I performed full‐sib breeding experiments in both the laboratory and the field to assess mean responses of each species to both its native host and the host of its congener, genetic variation within each species for traits associated with using each host, and tradeoffs in performance across hosts. I reared each beetle species on each host plant and measured larval consumption, survival, development time and growth. I measured only survival and growth in the field. Genetic correlations were calculated to assess tradeoffs in performance across hosts. In the laboratory experiment, larval survival of O. slobodkini on I. frutescens was lower and development time longer than on A. artemisiifolia. Survival of O. notulata on A. artemisiifolia was marginally lower than on I. frutescens while development time did not differ. There was little genetic variation among families in host use traits for either species. None of the estimates of genetic correlations were negative. The results of the field experiment support the results of the laboratory experiment. I conclude that O. notulata, the species with the derived host association, retains considerable ability to utilize the ancestral host plant, while O. slobodkini, the species witht he ancestral host association, does not show a similar ability to ut ilize the derived host. Tradeoffs in performance across hosts were not documented for either species of Ophraella. That notulata performs so well on A. artemissifolia suggests that intrinsic factors may not provide a sufficient explanation for the host specialization of this species on I. frutescens.
Costs and limits of phenotypic plasticity: Tests with predator‐induced morphology and life history in a freshwater snail
Authors: DeWitt T. J. 
Published: December 2004

AbstractPotential constraints on the evolution of phenotypic plasticity were tested using data from a previous study on predator‐induced morphology and life history in the freshwater snail Physa heterostropha. The benefit of plasticity can be reduced if facultative development is associated with energetic costs, developmental instability, or an impaired developmental range. I examined plasticity in two traits for 29 families of P. heterostropha to see if it was associated with growth rate or fecundity, within‐family phenotypic variance, or the potential to produce extreme phenotypes. Support was found for only one of the potential constraints. There was a strong negative selection gradient for growth rate associated with plasticity in shell shape (β = −0.3, P < 0.0001). This result was attributed to a genetic correlation between morphological plasticity and an antipredator behavior that restricts feeding. Thus, reduced growth associated with morphological plasticity may have had unmeasured fitness benefits. The growth reduction, therefore, is equivocal as a cost of plasticity. Using different fitness components (e.g., survival, fecundity, growth) to seek constraints on plasticity will yield different results in selection gradient analyses. Procedural and conceptual issues related to tests for costs and limits of plasticity are discussed, such as whether constraints on plasticity will be evolutionarily ephemeral and difficult to detect in nature.
Cumulative effects of founding events during colonisation on genetic diversity and differentiation in an island and stepping‐stone model
Authors: Le Corre V. , Kremer A. 
Published: December 2004

AbstractThis paper investigates the cumulative effect of founding events on the genetic differentiation and the within‐population heterozygosity in a metapopulation increasing its size by colonisation. Two contrasting models are considered: first, an island model, where migrants and colonists are taken at random from the entire metapopulation, and second, a linear stepping‐stone model, where migrants and colonists are sampled from a limited neighbourhood. The genetic consequences of a range expansion depend on the relative magnitudes of the number of colonists and migrants, in a way similar to extinction and colonisation processes (Wade and McCauley, 1988). The cumulative effect of founding events, resulting most often in a transient increase in genetic differentiation and a gradual loss of within‐population heterozygosity, also depends on the age‐structure that is established during colonisation. It is the highest when colonists are sampled from recently founded populations and migrants are exchanged among populations of similar ages. The genetic consequences of a range expansion are therefore far more pronounced and lasting in the linear stepping‐stone model than in the island model. These two models, however, represent the two extremes between which real populations will fall.
Host immune function and sexual selection in birds
Authors: Møller A. P. , Dufva R. , Erritzøe J. 
Published: December 2004

AbstractParasites have been hypothesized to affect sexual selection of their hosts, if secondary sexual characters reliably signal absence of infectious parasites, superior parenting ability caused by the absence of parasites, or heritable resistance to parasites, for which there is some intraspecific and interspecific evidence. Measures of immune defence of hosts provide reliable information on the current infection status of individuals of the chosen sex, usually males, and correlations between immune defence and development of secondary sexual characters thus provide a novel critical test of parasite‐mediated sexual selection. In a comparative study of birds, sexually dichromatic species had higher immune defences, measured in terms of leukocyte concentration and the size of spleen and bursa of Fabricius, respectively, than closely related, monochromatic species. Male plumage brightness was consistently negatively related to the size of the spleen in males of sexually dichromatic species, but not in males of monochromatic species. Hence, the brightest males, which frequently are preferred as mates by choosy females, had low levels of immune defence, suggesting that such males were healthy. This provides evidence for a general role of parasites in sexual selection among their bird hosts.
Wolbachia affects oviposition and mating behaviour of its spider mite host
Authors: Vala F. , Egas M. , Breeuwer J. A. J. , Sabelis M. W. 
Published: December 2004

Abstract
Wolbachia bacteria are transmitted from mother to offspring via the cytoplasm of the egg. When mated to males infected with Wolbachia bacteria, uninfected females produce unviable offspring, a phenomenon called cytoplasmic incompatibility (CI). Current theory predicts that ‘sterilization’ of uninfected females by infected males confers a fitness advantage to Wolbachia in infected females. When the infection is above a threshold frequency in a panmictic population, CI reduces the fitness of uninfected females below that of infected females and, consequently, the proportion of infected hosts increases. CI is a mechanism that benefits the bacteria but, apparently, not the host. The host could benefit from avoiding incompatible mates. Parasite load and disease resistance are known to be involved in mate choice. Can Wolbachia also be implicated in reproductive behaviour? We used the two-spotted spider mite – Wolbachia symbiosis to address this question. Our results suggest that uninfected females preferably mate to uninfected males while infected females aggregate their offspring, thereby promoting sib mating. Our data agrees with other results that hosts of Wolbachia do not necessarily behave as innocent bystanders – host mechanisms that avoid CI can evolve.
Variation in Male Calling Behaviour and Relation to Male Mating Success in the Strawberry Poison Frog (Dendrobates pumilio)
Authors: Pröhl Heike 
Published: December 2004

AbstractCalling behaviour and the characteristics of the males’ call are important for mate attraction, female mate choice and male mating success in anurans. In this study I investigated the variation in calling activity and the variation in one spectral (dominant frequency) and four temporal properties (call rate, call duration, duty cycle and pulse rate) of the advertisement call of strawberry poison frogs, Dendrobates pumilio, in two Costa Rican populations during two study periods. Regarding all call properties, no differences were found between populations or years, but between‐male variation was significantly higher than within‐recording and within‐male variation. Dominant frequency was less variable within and among males than temporal call properties and I classified the former as static and the latter as intermediate properties of the call. No call property seemed to be strongly affected by body length or weight. Moreover, I used behavioural observations to relate male calling behaviour to mating success. Calling activity was more variable between males and accounted for more variability in mating success in multiple regression models than any call property. Some call properties (call rate, dominant frequency and pulse rate) were also related to male mating success in one or two study periods. These call properties are probably important for females during courtship to assess their prospective mate and/or for competitive male–male interactions. Furthermore, I compared call properties and mating success of some males for which data were available for both study periods. Pulse rate was lower in the second than in the first year, suggesting age‐related changes in this call property. Moreover, male D. pumilio increased their relative mating success from the first to the second study year. Together with other studies, the data of this study suggest that, in anurans, endurance rivalry contributes more to variation in male mating success than does female choice based on male characteristics.
Mutual Mate Assessment in Wolf Spiders: Differences in the Cues Used by Males and Females
Authors: Rypstra Ann L. , Wieg Christina , Walker Sean E. , Persons Matthew H. 
Published: December 2004

AbstractWhen males engage in conspicuous courtship displays, it seems obvious that females would use characteristics of that display in mating decisions. However, males must also have a way to identify and evaluate females prior to engaging in what might be a costly mating ritual. Although it was known that female wolf spiders of the speciesPardosa milvina(Araneae; Lycosidae) attract males using volatile chemical cues, the nature of the cues used by males and females in mate selection had not been investigated. Specifically we determined whether males could detect the mating status of the female and if chemotactile cues from the female played a role in that process. In addition, we quantified conspicuous aspects of the male courtship (leg raises and body shakes) to determine if courtship intensity was related to female choice. Although repeated mating occurred in our studies, males were more likely to court and mate with virgin females. Males used substrate‐borne cues deposited by females to discriminate between mated and virgin females. Females used the conspicuous behaviors of males during courtship, body shakes and leg raises, in mate selection. Thus males and females use different kinds of information and different sensory modalities to assess the suitability of a potential mate.
Amarillo Fish (Girardinichthys multiradiatus) Use Visual Landmarks to Orient in Space
Authors: de Perera Burt T. , Macías Garcia C. 
Published: December 2004

AbstractFish responsiveness to visual stimuli has been studied extensively in contexts such as female mate choice, predator inspection and schooling, yet surprisingly little work has been conducted on visual orientation in space in fish. Here we report on an experiment designed to test whether Amarillo fish can learn to find a goal within a maze more effectively in the presence of local visual landmarks than otherwise. We found that: (a) Amarillo fish can use landmarks to locate a goal, (b) there was no observed difference in the ability to use visual landmarks between two populations and (c) overall navigational performance differed between two populations of Amarillo fish: individuals from a permanently turbid eutrophic pond performed better than those from a pond with clear waters. We hypothesize that fish that inhabit clear waters possess poorer navigational capabilities than fish from turbid waters because they normally rely on goal‐oriented behaviour, which requires neither egocentric nor environmental clues to navigate. This paper adds to the literature on the links between habitat characteristics and population differences in performance.
A Contrast in Extra‐Pair Paternity Levels on Mainland and Island Populations of Mediterranean Blue Tits
Authors: Charmantier Anne , Blondel Jacques 
Published: December 2004

AbstractExtra‐pair copulation (EPC) is a widespread behaviour amongst birds, yet the rate of occurrence of extra‐pair offspring is highly variable both within and across species. Two populations of Mediterranean blue tits, Parus caeruleus, one on the mainland and the other on the island of Corsica, are characterized by high levels of extra‐pair paternity (EPP), with 14 and 25% of extra‐pair offspring (in 46 and 68% of the nests), respectively. The rate of EPP is significantly higher in the island population. Such high rates on Corsica contradict the predictions of higher mate fidelity and lower levels of EPP on islands. Despite expressing several traits that characterize an insular syndrome, blue tits of Corsica do not exhibit lower genetic variation which could be associated with low levels of EPP on islands. Furthermore, our results do not support any of the hypotheses that have been proposed so far to explain variation in EPP rates at the local level. We tentatively suggest that proximate Mediterranean constraints, especially consistent food shortage, prompt females to seek better breeding opportunities through a two‐step process including high rates of EPC and divorce.
Vocal Coordination of Group Movement by Green Woodhoopoes (Phoeniculus purpureus)
Authors: Radford A. N. 
Published: December 2004

AbstractCommunication signals are used by many species to maintain group cohesion when moving over larger areas. Groups of green woodhoopoes (Phoeniculus purpureus) generally move around their territory as a close‐knit unit. Dominant individuals were more likely than subordinates to initiate movement to a new foraging site, but there was no intersexual difference. Dominants were also more likely than subordinates to be followed immediately. Vocalizations were shown to play an important role in mobilization: in the thick forests inhabited by woodhoopoes, visual cues to coordinate movement are likely to be less successful. When responding to the rallying call of a neighboring group, dominants and subordinates were equally likely to lead, as were males and females. As other group members followed immediately on most of these occasions, vocalizations were less important in this context than when moving to a new foraging site.
Hepatitis C virus and lichen planus
Authors: NAGAO YUMIKO , SATA MICHIO 
Published: December 2004

AbstractHepatitis C virus (HCV) is an important factor in the development of chronic liver disease and hepatocellular carcinoma. In recent years it has become known that HCV induces various extrahepatic manifestations including mixed cryoglobulinemia, membranoproliferative glomerulonephritis, Sjögren's syndrome, autoimmune thyroiditis, malignant lymphoma, porphyria cutanea tarda and lichen planus. Although the mechanisms of extrahepatic manifestations remain unclear, it is known that interferon (IFN) therapy and coadministration of IFN with ribavirin are effective in promoting the disappearance or alleviation of such extrahepatic lesions, which have tended to be overlooked. The present review focuses on lichen planus, one of the major extrahepatic manifestations.© 2004 Blackwell Publishing Asia Pty Ltd