共查询到20条相似文献,搜索用时 15 毫秒
1.
Jeffrey C. Oliver Kendra A. Robertson Antónia Monteiro 《Proceedings. Biological sciences / The Royal Society》2009,276(1666):2369-2375
Visual patterns in animals may serve different functions, such as attracting mates and deceiving predators. If a signal is used for multiple functions, the opportunity arises for conflict among the different functions, preventing optimization for any one visual signal. Here we investigate the hypothesis that spatial separation of different visual signal functions has occurred in Bicyclus butterflies. Using phylogenetic reconstructions of character evolution and comparisons of evolutionary rates, we found dorsal surface characters to evolve at higher rates than ventral characters. Dorsal characters also displayed sex-based differences in evolutionary rates more often than did ventral characters. Thus, dorsal characters corresponded to our predictions of mate signalling while ventral characters appear to play an important role in predator avoidance. Forewing characters also fit a model of mate signalling, and displayed higher rates of evolution than hindwing characters. Our results, as well as the behavioural and developmental data from previous studies of Bicyclus species, support the hypothesis that spatial separation of visual signal functions has occurred in Bicyclus butterflies. This study is the first to demonstrate, in a phylogenetic framework, that spatial separation of signals used for mate signalling and those used for predator avoidance is a viable strategy to accommodate multiple signal functions. This signalling strategy has important ramifications on the developmental evolution of wing pattern elements and diversification of butterfly species. 相似文献
2.
Tomoko Okamoto Atsushi Kawakita Ryutaro Goto Glenn P. Svensson Makoto Kato 《Proceedings. Biological sciences / The Royal Society》2013,280(1772)
Zoophilous flowers often transmit olfactory signals to attract pollinators. In plants with unisexual flowers, such signals are usually similar between the sexes because attraction of the same animal to both male and female flowers is essential for conspecific pollen transfer. Here, we present a remarkable example of sexual dimorphism in floral signal observed in reproductively highly specialized clades of the tribe Phyllantheae (Phyllanthaceae). These plants are pollinated by species-specific, seed-parasitic Epicephala moths (Gracillariidae) that actively collect pollen from male flowers and pollinate the female flowers in which they oviposit; by doing so, they ensure seeds for their offspring. We found that Epicephala-pollinated Phyllanthaceae plants consistently exhibit major qualitative differences in scent between male and female flowers, often involving compounds derived from different biosynthetic pathways. In a choice test, mated female Epicephala moths preferred the scent of male flowers over that of female flowers, suggesting that male floral scent elicits pollen-collecting behaviour. Epicephala pollination evolved multiple times in Phyllantheae, at least thrice accompanied by transition from sexual monomorphism to dimorphism in floral scent. This is the first example in which sexually dimorphic floral scent has evolved to signal an alternative reward provided by each sex, provoking the pollinator''s legitimate altruistic behaviour. 相似文献
3.
Sexual dimorphism (SD) in morphological, behavioural and physiological features is common, but the genetics of SD in the wild has seldom been studied in detail. We investigated the genetic basis of SD in morphological traits of threespine stickleback (Gasterosteus aculeatus) by conducting a large breeding experiment with fish from an ancestral marine population that acts as a source of morphological variation. We also examined the patterns of SD in a set of 38 wild populations from different habitats to investigate the relationship between the genetic architecture of SD of the marine ancestral population in relation to variation within and among natural populations. The results show that genetic architecture in terms of heritabilities, additive genetic variances and covariances (as well as correlations) is very similar in the two sexes in spite of the fact that many of the traits express significant SD. Furthermore, population differences in threespine stickleback body shape and armour SD appear to have evolved despite constraints imposed by genetic architecture. This implies that constraints for the evolution of SD imposed by strong genetic correlations are not as severe and absolute as commonly thought. 相似文献
4.
The swimbladder plays an important role in buoyancy regulation but is typically reduced or even absent in benthic freshwater fishes that inhabit fast flowing water. Here, we document, for the first time, a remarkable example of swimbladder sexual dimorphism in the highly rheophilic South Asian torrent minnows (Psilorhynchus). The male swimbladder is not only much larger than that of the female (up to five times the diameter and up to 98 times the volume in some cases), but is also structurally more complex, with multiple internal septa dividing it into smaller chambers. Males also exhibit a strange organ of unknown function or homology in association with the swimbladder that is absent in females. Extreme sexual dimorphism of non-gonadal internal organs is rare among vertebrates and the swimbladder sexual dimorphisms that we describe for Psilorhynchus are unique among fishes. 相似文献
5.
The origins of sexual dimorphism in body size in ungulates 总被引:4,自引:0,他引:4
Pérez-Barbería FJ Gordon IJ Pagel M 《Evolution; international journal of organic evolution》2002,56(6):1276-1285
Jarman (1974) proposed a series of relationships between habitat use, food dispersion, and social behavior and hypothesized a series of evolutionary steps leading to sexual dimorphism in body size through sexual selection in African antelope species. The hypothesis states that sexual size dimorphism evolved in a three-step process. Initially, ancestral monomorphic and monogamous ungulate species occupying closed habitats radiated into open grassland habitats. Polygynous mating systems then rapidly evolved in response to the aggregation of males and females, perhaps in relation to the clumped distribution of food resources in open habitats. Subsequently, size dimorphism evolved in those species occupying open habitats, but not in species that remained in closed habitats or retained monogamy. This hypothesis has played an important role in explaining the origins of sexual dimorphism in mammals. However, the temporal sequence of the events that Jarman proposed has never been demonstrated. Here we use a phylogeny of extant ungulate species, along with maximum-likelihood statistical techniques, to provide a test of Jarman's hypothesis. 相似文献
6.
Monarch butterflies (Danaus plexippus) depend on the presence of host plants (Asclepias spp.) within their breeding range for reproduction. In the southern Great Plains, Asclepias viridis is a perennial that flowers in May and June, and starts to senesce by August. It is locally abundant and readily used by monarchs as a host plant. We evaluated the effects of summer prescribed fire on A. viridis and the use of A. viridis by monarch butterflies. Summer prescribed fire generated a newly emergent population of A. viridis that was absent in other areas. Pre-migrant monarch butterflies laid eggs on A. viridis in summer burned plots in late August and September, allowing adequate time for a new generation of adult monarchs to emerge and migrate south to their overwintering grounds. Thus, summer prescribed fire may provide host plant patches and/or corridors for pre-migrant monarchs during a time when host plant availability may be limited in other areas. 相似文献
7.
Climate change is advancing the onset of the growing season and this is happening at a particularly fast rate in the High Arctic. However, in most species the relative fitness implications for males and females remain elusive. Here, we present data on 10 successive cohorts of the wolf spider Pardosa glacialis from Zackenberg in High-Arctic, northeast Greenland. We found marked inter-annual variation in adult body size (carapace width) and this variation was greater in females than in males. Earlier snowmelt during both years of its biennial maturation resulted in larger adult body sizes and a skew towards positive sexual size dimorphism (females bigger than males). These results illustrate the pervasive influence of climate on key life-history traits and indicate that male and female responses to climate should be investigated separately whenever possible. 相似文献
8.
Romain Derelle Tsuyoshi Momose Michael Manuel Corinne Da Silva Patrick Wincker Evelyn Houliston 《RNA (New York, N.Y.)》2010,16(4):696-707
Replacement of mRNA 5′ UTR sequences by short sequences trans-spliced from specialized, noncoding, spliced leader (SL) RNAs is an enigmatic phenomenon, occurring in a set of distantly related animal groups including urochordates, nematodes, flatworms, and hydra, as well as in Euglenozoa and dinoflagellates. Whether SL trans-splicing has a common evolutionary origin and biological function among different organisms remains unclear. We have undertaken a systematic identification of SL exons in cDNA sequence data sets from non-bilaterian metazoan species and their closest unicellular relatives. SL exons were identified in ctenophores and in hydrozoan cnidarians, but not in other cnidarians, placozoans, or sponges, or in animal unicellular relatives. Mapping of SL absence/presence obtained from this and previous studies onto current phylogenetic trees favors an evolutionary scenario involving multiple origins for SLs during eumetazoan evolution rather than loss from a common ancestor. In both ctenophore and hydrozoan species, multiple SL sequences were identified, showing high sequence diversity. Detailed analysis of a large data set generated for the hydrozoan Clytia hemisphaerica revealed trans-splicing of given mRNAs by multiple alternative SLs. No evidence was found for a common identity of trans-spliced mRNAs between different hydrozoans. One feature found specifically to characterize SL-spliced mRNAs in hydrozoans, however, was a marked adenosine enrichment immediately 3′ of the SL acceptor splice site. Our findings of high sequence divergence and apparently indiscriminate use of SLs in hydrozoans, along with recent findings in other taxa, indicate that SL genes have evolved rapidly in parallel in diverse animal groups, with constraint on SL exon sequence evolution being apparently rare. 相似文献
9.
N. S. Flanagan M. J. Blum A. Davison M. Alamo R. Albarrn K. Faulhaber E. Peterson W. O. McMillan 《Molecular ecology resources》2002,2(4):398-401
The Heliconius butterflies offer exceptional opportunities for the study of the ecology and evolution of mimicry. Despite previous reports of difficulties in the development of microsatellite loci in Lepidoptera, we characterize 15 polymorphic loci in H. erato that show promise for genetic mapping and population studies in this and other species. Levels of variation were high, in both numbers and size ranges of alleles. The loci showed broad amplification success across the genus and in two other genera. All loci that amplified in a population of H. melpomene were polymorphic. 相似文献
10.
Background and Aims
Heterostyly is a floral polymorphism characterized by the reciprocal position of stamens and stigmas in different flower morphs in a population. This reciprocal herkogamy is usually associated with an incompatibility system that prevents selfing and intra-morph fertilization, termed a heteromorphic incompatibility system. In different evolutionary models explaining heterostyly, it has been alternately argued that heteromorphic incompatibility either preceded or followed the evolution of reciprocal herkogamy. In some models, reciprocal herkogamy and incompatibility have been hypothesized to be linked together during the evolution of the heterostylous system.Methods
We examine the incompatibility systems in species with different stylar polymorphisms from the genera Lithodora and Glandora (Boraginaceae). We then test whether evolution towards reciprocal herkogamy is associated with the acquisition of incompatibility. To this end, a phylogeny of these genera and related species is reconstructed and the morphological and reproductive changes that occurred during the course of evolution are assessed.Key Results
Both self-compatibility and self-incompatibility are found within the studied genera, along with different degrees of intra-morph compatibility. We report for the first time extensive variability among members of the genus Glandora and related species in terms of the presence or absence of intraspecies polymorphism and heteromorphic incompatibility. Overall, our results do not support a tight link between floral polymorphism and incompatibility systems.Conclusions
The independent evolution of stylar polymorphism and incompatibility appears to have occurred in this group of plants. This refutes the canonical view that there is strong linkage between these reproductive traits. 相似文献11.
Vélez-Juarbe J Brochu CA Santos H 《Proceedings. Biological sciences / The Royal Society》2007,274(1615):1245-1254
The Indian gharial (Gavialis gangeticus) is not found in saltwater, but the geographical distribution of fossil relatives suggests a derivation from ancestors that lived in, or were at least able to withstand, saline conditions. Here, we describe a new Oligocene gharial, Aktiogavialis puertoricensis, from deltaic-coastal deposits of northern Puerto Rico. It is related to a clade of Neogene gharials otherwise restricted to South America. Its geological and geographical settings, along with its phylogenetic relationships, are consistent with two scenarios: (i) that a single trans-Atlantic dispersal event during the Tertiary explains the South American Neogene gharial assemblage and (ii) that stem gharials were coastal animals and their current restriction to freshwater settings is a comparatively recent environmental shift for the group. This discovery highlights the importance of including fossil information in a phylogenetic context when assessing the ecological history of modern organisms. 相似文献
12.
Yukitomo Arao Yuka Igarashi Fujio Kayama Eiji Kobayashi 《Biochemical and biophysical research communications》2009,382(1):46-50
We previously created the Alb-DsRed2 transgenic (Tg) rat that specifically expresses the red fluorescent protein, DsRed2, in the liver. Herein, we demonstrate that the DsRed2 expression is sexually dimorphic and exhibits a male-specific pattern. The profiling of sexual dimorphism in DsRed2 expression during pre-pubertal development was investigated using an in vivo fluorescent imaging analysis. The DsRed2 expression decreased gradually in both sexes until 28 days after birth. While DsRed2 expression was not persistent in the female liver, the male hepatic expression increased again at 35 days. Sexual dimorphic DsRed2 expression did not change in gonadectomized male and female Tg-rats. However, female hepatic DsRed2 was induced 72 h after the hypophysectomy. Hepatocytes isolated from the female Tg-rats also revealed DsRed2 induction by 96 h in culture. These results suggest that the pituitary hormone suppresses the female hepatic DsRed2 expression causing the sexual dimorphism of DsRed2 expression. 相似文献
13.
Cedric K. W. Tan Hanne L?vlie Elisabeth Greenway Stephen F. Goodwin Tommaso Pizzari Stuart Wigby 《Proceedings. Biological sciences / The Royal Society》2013,280(1771)
Studies of mating preferences have largely neglected the potential effects of individuals encountering their previous mates (‘directly sexually familiar’), or new mates that share similarities to previous mates, e.g. from the same family and/or environment (‘phenotypically sexually familiar’). Here, we show that male and female Drosophila melanogaster respond to the direct and phenotypic sexual familiarity of potential mates in fundamentally different ways. We exposed a single focal male or female to two potential partners. In the first experiment, one potential partner was novel (not previously encountered) and one was directly familiar (their previous mate); in the second experiment, one potential partner was novel (unrelated, and from a different environment from the previous mate) and one was phenotypically familiar (from the same family and rearing environment as the previous mate). We found that males preferentially courted novel females over directly or phenotypically familiar females. By contrast, females displayed a weak preference for directly and phenotypically familiar males over novel males. Sex-specific responses to the familiarity of potential mates were significantly weaker or absent in Orco1 mutants, which lack a co-receptor essential for olfaction, indicating a role for olfactory cues in mate choice over novelty. Collectively, our results show that direct and phenotypic sexual familiarity is detected through olfactory cues and play an important role in sex-specific sexual behaviour. 相似文献
14.
Yi-Shan Chao Germinal Rouhan Victor B. Amoroso Wen-Liang Chiou 《Annals of botany》2014,114(1):109-124
Background and Aims
Pteris (Pteridaceae), comprising over 250 species, had been thought to be a monophyletic genus until the three monotypic genera Neurocallis, Ochropteris and Platyzoma were included. However, the relationships between the type species of the genus Pteris, P. longifolia, and other species are still unknown. Furthermore, several infrageneric morphological classifications have been proposed, but are debated. To date, no worldwide phylogenetic hypothesis has been proposed for the genus, and no comprehensive biogeographical history of Pteris, crucial to understanding its cosmopolitan distribution, has been presented.Methods
A molecular phylogeny of Pteris is presented for 135 species, based on cpDNA rbcL and matK and using maximum parsimony, maximum likelihood and Bayesian inference approaches. The inferred phylogeny was used to assess the biogeographical history of Pteris and to reconstruct the evolution of one ecological and four morphological characters commonly used for infrageneric classifications.Key Results
The monophyly of Pteris remains uncertain, especially regarding the relationship of Pteris with Actiniopteris + Onychium and Platyzoma. Pteris comprises 11 clades supported by combinations of ecological and morphological character states, but none of the characters used in previous classifications were found to be exclusive synapomorphies. The results indicate that Pteris diversified around 47 million years ago, and when species colonized new geographical areas they generated new lineages, which are associated with morphological character transitions.Conclusions
This first phylogeny of Pteris on a global scale and including more than half of the diversity of the genus should contribute to a new, more reliable infrageneric classification of Pteris, based not only on a few morphological characters but also on ecological traits and geographical distribution. The inferred biogeographical history highlights long-distance dispersal as a major process shaping the worldwide distribution of the species. Colonization of different niches was followed by subsequent morphological diversification. Dispersal events followed by allopatric and parapatric speciation contribute to the species diversity of Pteris. 相似文献15.
The taxonomy and distribution of the five species of Hypolycaena in Maluku are discussed and new locality records given. Corrections are made to the published taxonomy and distribution of Hypolycaena phorbas (Fabricius, 1793). This clarification enables a better understanding of the biogeography of the genus. Hypolycaena asahi Okubo, 2007, was originally described from a single female from Ambon and is here recorded from Seram. The male is described for the first time. 相似文献
16.
Background and Aims
The actual number of domestications of a crop is one of the key questions in domestication studies. Answers to this question have generally been based on relationships between wild progenitors and domesticated descendants determined with anonymous molecular markers. In this study, this question was investigated by determining the number of instances a domestication phenotype had been selected in a crop species. One of the traits that appeared during domestication of common bean (Phaseolus vulgaris) is determinacy, in which stems end with a terminal inflorescence. It has been shown earlier that a homologue of the arabidopsis TFL1 gene – PvTFL1y – controls determinacy in a naturally occurring variation of common bean.Methods
Sequence variation was analysed for PvTFL1y in a sample of 46 wild and domesticated accessions that included determinate and indeterminate accessions.Key Results
Indeterminate types – wild and domesticated – showed only synonymous nucleotide substitutions. Determinate types – observed only among domesticated accessions – showed, in addition to synonymous substitutions, non-synonymous substitutions, indels, a putative intron-splicing failure, a retrotransposon insertion and a deletion of the entire locus. The retrotransposon insertion was observed in 70 % of determinate cultivars, in the Americas and elsewhere. Other determinate mutants had a more restricted distribution in the Americas only, either in the Andean or in the Mesoamerican gene pool of common bean.Conclusions
Although each of the determinacy haplotypes probably does not represent distinct domestication events, they are consistent with the multiple (seven) domestication pattern in the genus Phaseolus. The predominance of determinacy in the Andean gene pool may reflect domestication of common bean prior to maize introduction in the Andes. 相似文献17.
Background
In conditions of nitrogen limitation, Saccharomyces cerevisiae strains differ in their fermentation capacities, due to differences in their nitrogen requirements. The mechanisms ensuring the maintenance of glycolytic flux in these conditions are unknown. We investigated the genetic basis of these differences, by studying quantitative trait loci (QTL) in a population of 133 individuals from the F2 segregant population generated from a cross between two strains with different nitrogen requirements for efficient fermentation.Results
By comparing two bulks of segregants with low and high nitrogen requirements, we detected four regions making a quantitative contribution to these traits. We identified four polymorphic genes, in three of these four regions, for which involvement in the phenotype was validated by hemizygote comparison. The functions of the four validated genes, GCN1, MDS3, ARG81 and BIO3, relate to key roles in nitrogen metabolism and signaling, helping to maintain fermentation performance.Conclusions
This study reveals that differences in nitrogen requirement between yeast strains results from a complex allelic combination. The identification of three genes involved in sensing and signaling nitrogen and specially one from the TOR pathway as affecting nitrogen requirements suggests a role for this pathway in regulating the fermentation rate in starvation through unknown mechanisms linking nitrogen signaling to glycolytic flux.Electronic supplementary material
The online version of this article (doi: 10.1186/1471-2164-15-495) contains supplementary material, which is available to authorized users. 相似文献18.
The identity and taxonomy of the genus Crassolabium are discussed based on examination of material of C. australe, its type species and its comparison with Iberian species of close genera. The existence of refractive masses (thickenings) at the inner core of lateral lips, the most distinctive diagnostic feature of Crassolabium, is considered to be of minor taxonomical significance because of its interspecific and even intraspecific variability. It is concluded that Crassolabium and Thonus are identical, and a reversal of precedence among both genera is suggested. Crassolabium australe is re-described, and some comments are provided on C. robustum, the second species in the genus. 相似文献
19.
R. Craig Stillwell Goggy Davidowitz 《Proceedings. Biological sciences / The Royal Society》2010,277(1701):3819-3826
The degree and/or direction of sexual size dimorphism (SSD) varies considerably among species and among populations within species. Although this variation is in part genetically based, much of it is probably due to the sexes exhibiting differences in body size plasticity. Here, we use the hawkmoth, Manduca sexta, to test the hypothesis that moths reared on different diet qualities and at different temperatures will exhibit sex-specific body size plasticity. In addition, we explore the proximate mechanisms that potentially create sex-specific plasticity by examining three physiological variables known to regulate body size in this insect: the growth rate, the critical weight (which measures the cessation of juvenile hormone secretion from the corpora allata) and the interval to cessation of growth (ICG; which measures the time interval between the critical weight and the secretion of the ecdysteroids that regulate pupation and metamorphosis). We found that peak larval mass of males and females did not exhibit sex-specific plasticity in response to diet or temperature. However, the sexes did exhibit sex-specific plasticity in the mechanism that controls size; males and females exhibited sex-specific plasticity in the growth rate and the critical weight in response to both diet and temperature, whereas the ICG only exhibited sex-specific plasticity in response to diet. Our results suggest it is important for the sexes to maintain the same degree of SSD across environments and that this is accomplished by the sexes exhibiting differential sensitivity of the physiological factors that determine body size to environmental variation. 相似文献
20.
Females tend to be smaller than males in woody dioecious plant species, but they tend to be larger in herbs. The smaller size of females in woody species has been attributed to higher reproductive costs, yet no satisfactory explanation has been provided for their larger size in herbs. Because herbs have higher nitrogen concentrations in their tissues than woody plants, and because pollen is particularly rich in nitrogen, we predicted that male growth would be more compromised by reproduction than female growth. To test this hypothesis, we conducted three experiments on the annual dioecious herb Mercurialis annua. First, we compared the timing of reproduction between males and females and found that males started flowering earlier than females; early flowering is expected to compromise growth more than later flowering. Second, we compared plants allowed to flower with those prevented from flowering by experimental debudding and found that males incurred a higher reproductive cost than females in terms of both biomass and, particularly, nitrogen. Third, we grew plants under varying levels of nitrogen availability and found that although sexual size dimorphism was unaffected by nitrogen, females, but not males, decreased their relative allocation to both roots and reproduction under high nitrogen availability. We propose that males deal with the high cost of pollen production in terms of nitrogen by allocating biomass to nitrogen-harvesting roots, whereas females pay for carbon-rich seeds and fruits by investing in photosynthetic organs. Sexual dimorphism would thus seem to be the outcome of allocation to above- versus below-ground sinks that supply resources (carbon versus nitrogen) limiting the female and male reproduction differentially. 相似文献