Community assembly in temperate forest birds: habitat filtering,interspecific interactions and priority effects

Recent attempts to understand the processes governing community assembly have increasingly focused on patterns of phylogenetic relatedness and functional similarity among co-existing species. Considerations of the species pool, the number and identity of functional traits and the metrics used to identify patterns have come under scrutiny as possible influences on the detection of non-random patterns. Most mechanistic explanations of community assembly based on functional and phylogenetic approaches rely on deterministic explanations, while ignoring the role of stochastic processes and historical contingency, despite the prominent historical role of both types of explanations of species coexistence. We evaluated the phylogenetic and functional structure of 20 temperate forest bird assemblages in northeastern North America. We compared three approaches for characterizing the functional structure of assemblages. Regardless of approach, assemblages were generally no different than expected by chance. In contrast, phylogenetic structures of bird assemblages were overdispersed, clumped or consistent with random assembly depending on the site. Nonetheless, we found little evidence for differences in phylogenetic structure arising as a consequence of the identity of the species pool. We identified a strong relationship between the proportion of residents and phylogenetic relatedness that was unrelated to the species richness of assemblages. Our results suggest that different assembly mechanisms may structure resident and migratory subsets of temperate breeding bird communities. Resident assemblages are likely structured by interspecific interactions and habitat filtering prior to arrival of migrants. In contrast, the composition of migrant assemblages may be a consequence of priority effects in which the presence and abundance of residents and earliest arriving species affect the ability of subsequent migrants to colonize sites. This phenomenon enhances the likelihood of multiple alternative community structures in similar environments.     

The distribution of Wolbachia in fig wasps: correlations with host phylogeny,ecology and population structure

We surveyed for the presence and identity of Wolbachia in 44 species of chalcid wasps associated with 18 species of Panamanian figs. We used existing detailed knowledge of the population structures of the host wasps, as well as the ecological and evolutionary relationships among them, to explore the relevance of each of these factors to Wolbachia prevalence and mode of transmission. Fifty-nine per cent of these wasp species have Wolbachia infections, the highest proportion reported for any group of insects. Further, neither the presence nor the frequency of Wolbachia within hosts was correlated with the population structure of pollinator hosts. Phylogenetic analyses of wsp sequence data from 70 individuals representing 22 wasp species show that neither the close phylogenetic relationship nor close ecological association among host species is consistently linked to close phylogenetic affinities of the Wolbachia associated with them. Moreover, no genetic variation was detected within any Wolbachia strain from a given host species. Thus, the spread of Wolbachia within host species exceeds the rate of horizontal transmission among species and both exceed the rate of mutation of the wsp gene in Wolbachia. The presence and, in some cases, high frequency of Wolbachia infections within highly inbred species indicate that the Wolbachia either directly increase host fitness or are frequently horizontally transferred within these wasp species. However, the paucity of cospeciation of Wolbachia and their wasp hosts indicates that Wolbachia do not persist within a given host lineage for long time-periods relative to speciation times.     

Prey capture in lizards: differences in jaw–neck–forelimb coordination

Fish body muscles are arranged along the vertebral column in three‐dimensional W‐shaped blocks, called myomeres. Each myomere is separated from its neighbours by a collagenous sheet, the myoseptum, and embedded in these myosepta and in positions that are conserved throughout gnathostome evolution are distinct tendons. Within teleosts these tendons often ossify. Ossification is usually intramembranous but cartilaginous structures within the tendons have also been reported. Ossified myoseptal tendons are homologous to intermuscular bones and appear only in teleosts. The phylogenetic signal of myoseptal tendon ossfication has not been tested previously, although the presence and morphology of intermuscular bones have been used to infer phylogenetic relationships. We sample over a broad phylogenetic range of teleost fishes to test for (1) the effects of phylogenetic history on the presence of intermuscular bones and (2) morphological correlations with the presence of intermuscular bones. Body shape and fin position as well as vertebral number and aspect ratio are characters that are likely to affect the distribution of stresses along myoseptal tendons, and are therefore good functional predictors of myoseptal tendon ossification. We use the summary information by Patterson & Johnson for a list of species with intermuscular bones and reanalyse the homology of intermuscular bones to myoseptal tendons. We find that there is a phylogenetic signal in the distribution of four out of six ossified tendons, but that after correcting for phylogenetic relationships there are still morphological predictors for the presence of all ossified tendons. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 607–622.     

The larval head structures of Podagricomela shirahatai (Chûjô) (Chrysomelidae,Galerucinae, Alticini) and morphological effects of leaf mining

Head structures of the leaf mining larva of the chrysomelid species Podagricomela shirahatai are described and illustrated. Internal and external structures were reconstructed three dimensionally based on image stacks obtained with microcomputed tomography. The larval head is characterized by prognathism, a dorsoventrally compressed shape, a flattened maxillolabial complex, a completely reduced coronal suture, and the presence of a deep, V‐shaped posterior emargination of the head capsule. Internal structures are not distinctly affected by leaf mining. The cephalic features are compared with conditions found in surface feeding and root feeding alticine larvae and also with characters of chrysomeline larvae of Chrysomela populi Linnaeus. Possible correlations between modifications of the larval head and different feeding behaviors are discussed. Characters are also discussed with respect to possible phylogenetic implications. Some derived features are apparently due to phylogenetic constraints. Apomorphies characterizing alticine larvae with distinctly different life habits are the loss of M. frontoepharyngalis (M. 9), the origin of M. tentoriostipitalis (M. 18) from the head capsule, two insertions of M. tentoriopraementalis inferior (M. 29) and the reduction of stemmata. The study underlines that the anatomical study of chrysomeloid larvae is not only highly desirable in a phylogenetic context, but also crucial for understanding the evolution of different life strategies in this extremely successful group of Coleoptera. J. Morphol. 276:446–457, 2015. © 2014 Wiley Periodicals, Inc.     

Ontogeny, phylogeny, and morphology in anuran larvae: morphometric analysis of cranial development and evolution in Rana tadpoles (Anura: Ranidae)

Comparative studies of chondrocranial morphology in larval anurans are typically qualitative in nature, focusing primarily on discrete variation or gross differences in the size or shape of individual structures. Detailed data on chondrocranial allometry are currently limited to only two species, Rana sylvatica and Bufo americanus. This study uses geometric morphometric and multivariate statistical analyses to examine interspecific variation in both larval chondrocranial shape and patterns of ontogenetic allometry among six species of Rana. Variation is interpreted within the context of hypothesized phylogenetic relationships among these species. Canonical variates analyses of geometric morphometric datasets indicate that species can be clearly discriminated based on chondrocranial shape, even when whole ontogenies are included in the analysis. Ordinations and cluster analyses based on chondrocranial shape data indicate the presence of three primary groupings (R. sylvatica; R. catesbeiana + R. clamitans; and R. palustris + R. pipiens + R. sphenocephala), and patterns of similarity closely reflect phylogenetic relationships. Analysis of chondrocranial allometry reveals that some patterns are conserved across all species (e.g., most measurements scale with negative allometry, those associated with the posterior palatoquadrate tend to scale with isometry or positive allometry). Ontogenetic scaling along similar allometric trajectories, lateral transpositions of individual trajectories, and variable allometric relationships all contribute to shape differences among species. Overall patterns of similarity among ontogenetic trajectories also strongly reflect phylogenetic relationships. Thus, this study demonstrates a tight link between ontogeny, phylogeny, and morphology, and highlights the importance of including both ontogenetic and phylogenetic data in studies of chondrocranial evolution in larval anurans.     

Functional dissimilarity,not phylogenetic relatedness,determines interspecific interactions among plants in the Tibetan alpine meadows

The hypotheses suggesting that the nature and strength of species interactions should be determined by phylogenetic relatedness have important implications for the understanding of community structure. However, to date, there is limited empirical evidence to support them. At least two basic conditions need to be met in order to expect species interactions to be determined by evolutionary relatedness: a phylogenetic signal in the traits involved in the interactions and changes in the interactions as species are more ecologically similar. Here, we report results of a removal experiment in the Chinese Tibetan plateau in which we directly assessed if the nature and/or strength of interactions among twelve alpine meadow plant species were influenced by their phylogenetic relatedness and/or their functional dissimilarity. For each plant species, we compared its biomass production when grown alone to its biomass in presence of another species and used it as a measure of species interactions. Competition between pairs of species was more frequent than facilitation, with 60% of interactions resulting in plants producing less biomass when a second species was present. We found no effect of phylogenetic relatedness on the prevalence or intensity of competition or facilitation, presumably as none of the studied traits showed phylogenetic signal. Functional dissimilarity based on maximum plant height alone was the best predictor of both the prevalence and strength of competition and facilitation, followed by functional dissimilarity using all five functional traits. Our results pinpoint the limited capacity of phylogenetic relatedness as predictor of species interactions; underlining the limitations of using phylogenetic dispersion patterns to infer mechanisms of community assembly. On the contrary, when the right functional traits are used, functional dissimilarity among species can predict both the nature and strength of their interactions; accentuating the relevance of trait‐based approaches in community ecology research.     

Fire modifies the phylogenetic structure of soil bacterial co‐occurrence networks

Fire alters ecosystems by changing the composition and community structure of soil microbes. The phylogenetic structure of a community provides clues about its main assembling mechanisms. While environmental filtering tends to reduce the community phylogenetic diversity by selecting for functionally (and hence phylogenetically) similar species, processes like competitive exclusion by limiting similarity tend to increase it by preventing the coexistence of functionally (and phylogenetically) similar species. We used co‐occurrence networks to detect co‐presence (bacteria that co‐occur) or exclusion (bacteria that do not co‐occur) links indicative of the ecological interactions structuring the community. We propose that inspecting the phylogenetic structure of co‐presence or exclusion links allows to detect the main processes simultaneously assembling the community. We monitored a soil bacterial community after an experimental fire and found that fire altered its composition, richness and phylogenetic diversity. Both co‐presence and exclusion links were more phylogenetically related than expected by chance. We interpret such a phylogenetic clustering in co‐presence links as a result of environmental filtering, while that in exclusion links reflects competitive exclusion by limiting similarity. This suggests that environmental filtering and limiting similarity operate simultaneously to assemble soil bacterial communities, widening the traditional view that only environmental filtering structures bacterial communities.     

Bending for love: losses and gains of sexual dimorphisms are strictly correlated with changes in the mounting position of sepsid flies (Sepsidae: Diptera)

Background  

Sexually dimorphic structures ntribute the largest number of morphological differences between closely related insect species thus implying that these structures evolve fast and are involved in speciation. The current literature focuses on the selective forces that drive these changes, be it 'sexual conflict' or 'female choice'. However, there are only few studies examining the function of sexual dimorphisms and even fewer that investigate how functional changes influence dimorphisms. This is largely due to the paucity of taxa for which the morphology, behavior, and phylogenetic relationships for multiple species are known. Here we present such data for sepsid flies. Sepsids have starkly dimorphic forelegs whose function can be documented under laboratory conditions. We use data from 10 genes to reconstruct the phylogenetic relationships for 33 species and test whether mounting positions are correlated with the presence and absence of sexual dimorphisms in the forelegs.     

Increased copulation duration before ejaculate transfer is associated with larger spermatophores, and male genital titillators, across bushcricket taxa

Copulation duration varies considerably across species, but few comparative studies have examined factors that might underlie such variation. We examined the relationship between copulation duration (prior to spermatophore transfer), the complexity of titillators (sclerotized male genital contact structures), spermatophore mass and male body mass across 54 species of bushcricket. Using phylogenetic comparative analyses, we found that copulation duration was much longer in species with titillators than those without, but it was not longer in species with complex compared with simple titillators. A positive relationship was found between spermatophore size and copulation duration prior to ejaculate transfer, which supports the hypothesis that this represents a period of mate assessment. The slope of this relationship was steeper in species with simple rather than complex titillators. Although the data suggest that the presence of titillators is necessary to maintain long copulation prior to ejaculate transfer, mechanisms underlying this association remain unclear.     

The phylogenetic component of food web structure and intervality

Despite the exceptional complexity formed by species and their interactions in ecological networks, such as food webs, regularities in the network structures are repeatedly demonstrated. The interactions are determined by the characteristics of a species. The characteristics are in turn determined by the species’ phylogenetic relationships, but also by factors not related to evolutionary history. Here, we test whether species’ phylogenetic relationships provides a significant proxy for food web intervality. We thereafter quantify the degree to which different species traits remain valuable predictors of food web structure after the baseline effect of species’ relatedness has been removed. We find that the phylogenetic relationships provide a significant background from which to estimate food web intervality and thereby structure. However, we also find that there is an important, non-negligible part of some traits, e.g., body size, in food webs that is not accounted for by the phylogenetic relationships. Additionally, both these relationships differ depending if a predator or a prey perspective is adopted. Clearly, species’ evolutionary history as well as traits not determined by phylogenetic relationships shapes predator-prey interactions in food webs, and the underlying evolutionary processes take place on slightly different time scales depending on the direction of predator-prey adaptations.     

放牧干扰梯度下川西亚高山植物群落的组合机理

为了阐明放牧干扰对川西亚高山区域植物群落的组合过程以及群落结构的影响, 研究了放牧干扰梯度下的功能群均匀度和群落谱系结构的变化趋势。结果显示: 在干扰较轻的阔叶林与针叶林样地, 部分样方的功能群均匀度显著高于无效模型, 随着干扰梯度的增强, 功能群均匀度呈线性下降, 样方平均值从0.930降至0.840, 其高于无效模型的次数也逐渐降低, 干扰程度较大的草甸中出现部分样方的功能群均匀度显著低于无效模型。随着干扰程度的增强, 群落的谱系结构指数也呈逐渐上升趋势, 净关联指数平均值由-0.634逐渐增加至2.360, 邻近类群指数由-0.158上升至2.179。草甸与低矮灌丛受干扰较为严重, 其大部分样方的谱系结构指数显著高于随机群落, 表明干扰群落的谱系结构呈聚集分布。功能群均匀度与谱系结构的变化趋势一致, 表明生境筛滤效应与种间竞争作用的平衡决定着群落的组合过程。干扰降低了竞争作用, 促进了少数耐干扰功能群的优势地位, 造成功能群均匀度下降, 同时通过生境筛滤作用, 使群落的谱系结构呈现出聚集分布; 而未干扰的群落中由于竞争作用的效应, 功能群均匀度较高, 谱系结构也更加分散。研究区域植物群落的功能群均匀度与物种丰富度呈负相关, 表明物种间特别是相似物种间的竞争限制了群落的物种多样性。研究结果说明, 生态位分化和物种间的相互竞争在物种共存与群落组合中具有重要作用。     

Repetitive sequences originating from the centromere constitute large-scale heterochromatin in the telomere region in the siamang, a small ape

Chromosomes of the siamang Symphalangus syndactylus (a small ape) carry large-scale heterochromatic structures at their ends. These structures look similar, by chromosome C-banding, to chromosome-end heterochromatin found in chimpanzee, bonobo and gorilla (African great apes), of which a major component is tandem repeats of 32-bp-long, AT-rich units. In the present study, we identified repetitive sequences that are a major component of the siamang heterochromatin. Their repeat units are 171 bp in length, and exhibit sequence similarity to alpha satellite DNA, a major component of the centromeres in primates. Thus, the large-scale heterochromatic structures have different origins between the great apes and the small ape. The presence of alpha satellite DNA in the telomere region has previously been reported in the white-cheeked gibbon Nomascus leucogenys, another small ape species. There is, however, a difference in the size of the telomere-region alpha satellite DNA, which is far larger in the siamang. It is not known whether the sequences of these two species (of different genera) have a common origin because the phylogenetic relationship of genera within the small ape family is still not clear. Possible evolutionary scenarios are discussed.     

Phylogenetic effects, the loss of complex characters, and the evolution of development in calyptraeid gastropods

Abstract Despite considerable theoretical and empirical work on the population genetic effects of mode of development in benthic marine invertebrates, it is unclear what factors generate and maintain interspecific variation in mode of development and few studies have examined such variation in a phylogenetic context. Here I combine data on mode of development with a molecular phylogeny of 72 calyptraeid species to test the following hypotheses about the evolution of mode of development: (1) Is the loss of feeding larvae irreversible? (2) Is there a phylogenetic effect on the evolution of mode of development? (3) Do embryos of direct‐developing species lose the structures necessary for larval feeding and swimming and, if so, is the degree of embryonic modification correlated with the genetic distance between species? The results of these analyses suggest that mode of development evolves rapidly and with little phylogenetic inertia. There are three cases of the possible regain of feeding larvae, in all cases from direct development with nurse eggs. It appears that species with planktotrophic, lecithotrophic, or direct development with nurse eggs all have equal evolutionary potential and retain the possibility of subsequent evolution of a different mode of development. However, species with direct development from large yolky eggs appear to be subject to phylogenetic constraints and may not be able to subsequently evolve a different mode of development. Finally, species that have more recently evolved direct development have less highly modified embryos than older direct‐developing species. Since species with nurse eggs generally have fewer embryonic modifications than those from large yolky eggs, this embryological difference may be the underlying cause of the difference in evolutionary potential.     

Raphidiophrys heterophryoidea sp. nov. (Centrohelida: Raphidiophryidae), the first heliozoan species with a combination of siliceous and organic skeletal elements

Centrohelid heliozoans form a monophyletic group with uncertain affinities to other groups of protists. Except for a number of naked species, they have either siliceous scales or organic spicules covering the cell. According to the phylogenetic analysis of the 18S rDNA gene, it is hypothesized that scales are the ancestral form of cell coverings, while spicules are derived structures. The present paper describes a new species of centrohelids, Raphidiophrys heterophryoidea, isolated from the inner lakes of Valamo Island (North-Western Russia). This species has tangential scales, consisting of two plates, connected with radial, sometimes branched septa. Raphidiophrys heterophryoidea also has radially oriented spindle-shaped spicules. The organic nature of spicules and the siliceous nature of scales were verified by energy-dispersive X-ray microanalysis. Such a combination of organic and siliceous skeletal elements in one heliozoan is novel for any heliozoan species. The complex bipartite structure of scales suggested placing this new species in the genus Raphidiophrys. Consequently, the diagnoses of the genus Raphidiophrys and the family Raphidiophryidae were amended taking into account the optional presence of spicules. Raphidiophrys heterophryoidea presumably represents a stage of shift from scales to spicules, which, according to the molecular phylogenetic data, occurred at least twice in centrohelid evolution.     

Taxonomic status of Euphylliidae corals in Peninsular Malaysia based on morphological structures and phylogenetic analyses using mitochondrial COI gene

The morphological and molecular studies provide greater taxonomic resolution for the scleractinian coral identification. The Euphylliidae corals are among the scleractinian family for which their corallite and polyp morphologies have been examined for species identification. However, knowledge on the molecular study for coral identification in Malaysia is very limited. Therefore, this study aimed to examine the morphological structures and phylogenetic analyses for six Euphylliidae coral species using the mitochondrial gene of cytochrome oxidase subunit I (COI). The results showed that the Euphylliidae corals are present under both “complex” and “robust” coral clades as supported by many researchers. The result also revealed that the species phylogeny of Euphylliidae corals is in concordances with its morphological structures of corallites. It can be concluded the combination between morphological structures and phylogenetic analyses provide more accurate identification than relying on morphological study alone. Hence, it provides a future direction for the scleractinian research progress in species identification.     

中国南方两个革菌新种：中国丝皮革菌和棉絮丝皮革菌（丝皮革菌科,多孔菌目）

依据形态学和分子系统学研究结果,描述了产自中国云南省的丝皮革菌属2个新种,即中国丝皮革菌Hyphoderma sinense和棉絮丝皮革菌H. floccosum。中国丝皮革菌以光滑子实层体表面、被结晶和念珠状的囊状体及圆柱形至腊肠状的担孢子（8-11.5×3-5μm）为主要识别特征。棉絮丝皮革菌具有棉絮状至粉状子实层体表面、管状和分隔状囊状体及椭圆形至腊肠状担孢子。对新种的ITS和nLSU片段进行了测序和分析,采用最大似然法、最大简约法和贝叶斯推断法对研究样本的ITS+nLSU nrRNA基因序列进行系统发育分析,结果显示两个新种隶属于丝皮革菌属,其中,中国丝皮革菌与变形丝皮革菌聚在一起;棉絮丝皮革菌与松生丝皮革菌、丝皮革菌和拟丝皮革菌聚为一类。本研究提供了两新种的详细描述、线条图、生态照片及与相似种的区别,同时编写了我国丝皮革菌属23个种的检索表。     

Egg surface structure in the annual fishes Simpsonichthys (subgenera Ophthalmolebias and Xenurolebias) and Nematolebias (Teleostei: Cyprinodontiformes: Rivulidae): variability and phylogenetic significance

The surfaces of the egg chorion of nine species of Simpsonichthys , two of Nematolebias and eight other species of rivulids were studied with scanning electron microscopy revealing details of ornamentation that were previously undocumented. Surface structures of eggs of Simpsonichthys of the subgenus Ophthalmolebias are described for the first time: eggs of Simpsonichthys constanciae , Simpsonichthys perpendicularis , Simpsonichthys rosaceus and Simpsonichthys suzarti are ornamented with a very characteristic palm-like structure, that is restricted to these species among the rivulids examined. The surface of the egg chorion of Simpsonichthys bokermanni lacks the well-developed palm-like structure, but has a characteristic conical projection, distinct from the structures of other rivulids examined, that is proposed as homologous to the palm-like structure. Simpsonichthys bokermanni shares with Nematolebias papilliferus and Nematolebias whitei the presence of concentric rows of spiny projections around the micropylar region. Species of Simpsonichthys of the subgenus Ophthalmolebias , Simpsonichthys myersi (of the subgenus Xenurolebias ), and N. whitei share the presence of large rounded protuberances on the surface of the egg chorion. The phylogenetic significance of these features are evaluated and discussed in light of current knowledge about rivulid relationships.     

Comparative morphology of cercal structures in true crickets and their allies (Orthoptera, Ensifera): a phylogenetic perspective

 Cercal structures are surveyed in a large number of crickets sensu lato (Orthoptera, Ensifera, Gryllidea) to analyse their diversity and check for their potential phylogenetic interest. Several other Ensifera are also examined for outgroup comparisons. The main results indicate that Gryllidea can be characterised by several features of their cerci, namely the irregular alignment and the varied size of club-shaped setae. Peculiar features of cercal structures may also be autapomorphic of Gryllidea subclades, such as the presence of wedges on the surface of club-shaped setae (Grylloidea, Gryllotalpidae), the presence of scale-like setae (Mogoplistidae) or that of apical pores on trichoid setae (Myrmecophilidae, Myrmecophilinae), for example. At the scale of Ensifera, three characters are of phylogenetic interest: the presence of club-shaped setae in Gryllidea and Stenopelmatidae, the presence of inner rims inside the sockets of filiform and, when present, club-shaped setae in Gryllidea and, if confirmed, in Rhaphidophoridae, and the occurrence of microtrichiae on the cerci surface in Gryllidea and Rhaphidophoridae. Accepted: 4 October 1998