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New phylogenetic hypotheses for the core Chlorophyta based on chloroplast sequence data  [PDF]
Karolina Fu?íková,Frederik Leliaert,Endymion D. Cooper,Pavel ?kaloud,Olivier De Clerck,Carlos F. D. Gurgel,Louise A. Lewis,Paul O. Lewis,Juan M. Lopez-Bautista,Charles F. Delwiche,Heroen Verbruggen
Frontiers in Ecology and Evolution , 2014, DOI: 10.3389/fevo.2014.00063
Abstract: Phylogenetic relationships in the green algal phylum Chlorophyta have long been subject to debate, especially at higher taxonomic ranks (order, class). The relationships among three traditionally defined and well-studied classes, Chlorophyceae, Trebouxiophyceae, and Ulvophyceae are of particular interest, as these groups are species-rich and ecologically important worldwide. Different phylogenetic hypotheses have been proposed over the past two decades and the monophyly of the individual classes has been disputed on occasion. Our study seeks to test these hypotheses by combining high throughput sequencing data from the chloroplast genome with increased taxon sampling. Our results suggest that while many of the deep relationships are still problematic to resolve, the classes Trebouxiophyceae and Ulvophyceae are likely not monophyletic as currently defined. Our results also support relationships among several trebouxiophycean taxa that were previously unresolved. Finally, we propose that the common term for the grouping of the three classes, “UTC clade,” be replaced with the term “core Chlorophyta” for the well-supported clade containing Chlorophyceae, taxa belonging to Ulvophyceae and Trebouxiophyceae, and the classes Chlorodendrophyceae and Pedinophyceae.
Testing Phylogenetic Hypotheses of the Subgenera of the Freshwater Crayfish Genus Cambarus (Decapoda: Cambaridae)  [PDF]
Jesse W. Breinholt, Megan L. Porter, Keith A. Crandall
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0046105
Abstract: Background The genus Cambarus is one of three most species rich crayfish genera in the Northern Hemisphere. The genus has its center of diversity in the Southern Appalachians of the United States and has been divided into 12 subgenera. Using Cambarus we test the correspondence of subgeneric designations based on morphology used in traditional crayfish taxonomy to the underlying evolutionary history for these crayfish. We further test for significant correlation and explanatory power of geographic distance, taxonomic model, and a habitat model to estimated phylogenetic distance with multiple variable regression. Methodology/Principal Findings We use three mitochondrial and one nuclear gene regions to estimate the phylogenetic relationships for species within the genus Cambarus and test evolutionary hypotheses of relationships and associated morphological and biogeographical hypotheses. Our resulting phylogeny indicates that the genus Cambarus is polyphyletic, however we fail to reject the monophyly of Cambarus with a topology test. The majority of the Cambarus subgenera are rejected as monophyletic, suggesting the morphological characters used to define those taxa are subject to convergent evolution. While we found incongruence between taxonomy and estimated phylogenetic relationships, a multiple model regression analysis indicates that taxonomy had more explanatory power of genetic relationships than either habitat or geographic distance. Conclusions We find convergent evolution has impacted the morphological features used to delimit Cambarus subgenera. Studies of the crayfish genus Orconectes have shown gonopod morphology used to delimit subgenera is also affected by convergent evolution. This suggests that morphological diagnoses based on traditional crayfish taxonomy might be confounded by convergent evolution across the cambarids and has little utility in diagnosing relationships or defining natural groups. We further suggest that convergent morphological evolution appears to be a common occurrence in invertebrates suggesting the need for careful phylogenetically based interpretations of morphological evolution in invertebrate systematics.
Evolution of microgastropods (Ellobioidea, Carychiidae): integrating taxonomic, phylogenetic and evolutionary hypotheses  [cached]
Weigand Alexander M,Jochum Adrienne,Slapnik Rajko,Schnitzler Jan
BMC Evolutionary Biology , 2013, DOI: 10.1186/1471-2148-13-18
Abstract: Background Current biodiversity patterns are considered largely the result of past climatic and tectonic changes. In an integrative approach, we combine taxonomic and phylogenetic hypotheses to analyze temporal and geographic diversification of epigean (Carychium) and subterranean (Zospeum) evolutionary lineages in Carychiidae (Eupulmonata, Ellobioidea). We explicitly test three hypotheses: 1) morphospecies encompass unrecognized evolutionary lineages, 2) limited dispersal results in a close genetic relationship of geographical proximally distributed taxa and 3) major climatic and tectonic events had an impact on lineage diversification within Carychiidae. Results Initial morphospecies assignments were investigated by different molecular delimitation approaches (threshold, ABGD, GMYC and SP). Despite a conservative delimitation strategy, carychiid morphospecies comprise a great number of unrecognized evolutionary lineages. We attribute this phenomenon to historic underestimation of morphological stasis and phenotypic variability amongst lineages. The first molecular phylogenetic hypothesis for the Carychiidae (based on COI, 16S and H3) reveals Carychium and Zospeum to be reciprocally monophyletic. Geographical proximally distributed lineages are often closely related. The temporal diversification of Carychiidae is best described by a constant rate model of diversification. The evolution of Carychiidae is characterized by relatively few (long distance) colonization events. We find support for an Asian origin of Carychium. Zospeum may have arrived in Europe before extant members of Carychium. Distantly related Carychium clades inhabit a wide spectrum of the available bioclimatic niche and demonstrate considerable niche overlap. Conclusions Carychiid taxonomy is in dire need of revision. An inferred wide distribution and variable phenotype suggest underestimated diversity in Zospeum. Several Carychium morphospecies are results of past taxonomic lumping. By collecting populations at their type locality, molecular investigations are able to link historic morphospecies assignments to their respective evolutionary lineage. We propose that rare founder populations initially colonized a continent or cave system. Subsequent passive dispersal into adjacent areas led to in situ pan-continental or mountain range diversifications. Major environmental changes did not influence carychiid diversification. However, certain molecular delimitation methods indicated a recent decrease in diversification rate. We attribute this decrease to protracted speciation.
Foraging Activity of Native Ants on Trees in Forest Fragments Colonized by the Invasive Ant Lasius neglectus  [PDF]
C. Paris,X. Espadaler
Psyche , 2012, DOI: 10.1155/2012/261316
Abstract: Our aim was to investigate the foraging activity of native ants on tree trunks in accordance with their location in forest fragments and the presence or absence of the invasive ant Lasius neglectus. Trees were categorized as isolated, edge, or core trees according to their location in forest fragments. In invaded fragments, Lasius neglectus had the highest spatial-temporal tree visitation. Isolated trees were visited more and for a longer time by this invasive ant. Invaded fragments had low native ant activity on trees compared to fragments without L. neglectus. The few encountered native ant species showed a lower frequency of visitation and for less time in comparison with their spatial-temporal visitation in control fragments. Crematogaster scutellaris and Temnothorax lichtensteini visited all tree categories in both fragments (invaded or control) but Lasius grandis stayed for longer on isolated trees from control fragments. We conclude that in fragments invaded by Lasius neglectus, the richness of native ant foraging on trees was negatively affected. Isolated trees close to roads could act as dispersal stepping stones for Lasius neglectus. 1. Introduction In ants, daily and seasonal foraging activity is mainly modulated by the interaction of abiotic and biotic variables [1–4]. Temperature of soil surface and relative humidity has been reported as the most relevant variables that influence ant foraging [5]. However, other abiotic variables such as sunlight, rainfall, wind intensity, atmospheric pressure, and light intensity may influence the activity of some ant species [6–9]. Foraging activity determined by physical variables is modulated by biotic variables such as interspecific competition and habitat structure [3], resource productivity [10], food type, and colony needs [11] and physiological constraints such as heat tolerance [7]. Additionally, the activity of dominant species (sensu [12]) may determine the foraging patterns of less dominant species [13]. In this regard, invasive ant species become dominant because of their aggressive behavior and the major abundance that their unicolonial social structure and polygyny (many queens per colony) allow them to achieve in a short time. In consequence, invasive ants monopolize food sources, mainly honeydew-producing insects, negatively affect native arthropods and even small vertebrates, and disrupt and develop mutualisms in native communities [14]. In short, ant-aphid interactions may have strong and pervasive effects extending across multiple trophic levels [15]. The invasive ant Lasius neglectus
Why biogeographical hypotheses need a well supported phylogenetic framework: a conceptual evaluation
Santos, Charles Morphy D.;Amorim, Dalton S.;
Papéis Avulsos de Zoologia (S?o Paulo) , 2007, DOI: 10.1590/S0031-10492007000400001
Abstract: a growing number of biogeographical methods have attempted to describe formal means of reconstructing the biogeographical history of the organisms. whatever the biogeographical method, however, the source of systematic information has to be well worked out. taxonomic noise is sometimes a true impediment to properly deal with the complexity of life in its three-dimensional aspects, the threefold parallelism represented by form, space and time. this paper argues that historical systematics is a necessary basis for a historical biogeography. organismal phylogenies or at least hypotheses of monophyly should be taken as the basis for the study of distribution patterns. whenever a non-monophyletic taxon is misleadingly taken as monophyletic, erroneous interpretations in evolutionary analyses necessarily follow. when the proportion of paraphyletic taxa considered in an analysis is small, a general pattern may be obtained, but the interpretation of the biogeographical evolution of each paraphyletic taxon will be equivocated. the delimitation of areas of endemism also depends on the precision of the recovered phylogenetic information. indices based on phylogenetic diversity allow the delimitation of areas for conservation of biological diversity. despite the plethora of current available biogeographical methods, biogeography is not a mess, as was pointed elsewhere. the order in the discipline is subtle: as biogeography intends to comprehend the living world based on the study of the form, space and time, a phylogenetic framework is a basic requirement. the lack of reliable biogeographical primary information - historical taxa - certainly creates severe obstacles for historical biogeography.
Sperm Bundles in the Seminal Vesicles of Sexually Mature Lasius Ant Males  [PDF]
William E. Burnett, Jürgen Heinze
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0093383
Abstract: In many insects, sperm cells are produced in bundles with their heads being held together by a glycoprotein matrix secreted by a cyst cell. Mature sperm cells in the seminal vesicles are usually free, but in sawflies and several other insects, such structures (spermatodesmata) remain intact and sperm cells may be ejaculated as bundles. Here we report the occurrence of spermatodesmata in mature males of the ant Lasius pallitarsis. Microscopic investigations of the abdominal contents of males immediately prior to their nuptial flights showed that the anterior ends of numerous sperm cells were embedded in an oval-shaped 20 by 30 micrometer extracellular fibrous cap. Individual sperm ranged in length from 55 to 75 micrometers with an average overall length of 65 micrometers. The bulb-shaped heads of the sperm were relatively small, only about 1.5 micrometers in length and about 1.1 micrometers in diameter. The diameter of the sperm tails was approximately 1 micrometer. Observations of live preparations of the spermatodesmata showed increasingly active undulating wave-like movement of the sperm tails as the slide preparations aged. This appears to be the first case of sperm bundles being present in the seminal vesicles of mature ant males – males that are immediately poised to complete their nuptial mating flight.
Impact of Interference Competition on Exploration and Food Exploitation in the Ant Lasius niger  [PDF]
Vincent Fourcassié,Tristan Schmitt,Claire Detrain
Psyche , 2012, DOI: 10.1155/2012/383757
Abstract: Competition acts as a major force in shaping spatially and/or temporally the foraging activity of ant colonies. Interference competition between colonies in particular is widespread in ants where it can prevent the physical access of competitors to a resource, either directly by fighting or indirectly, by segregating the colony foraging areas. Although the consequences of interference competition on ant distribution have been well studied in the literature, the behavioral mechanisms underlying interference competition have been less explored. Little is known on how ants modify their exploration patterns or the choice of a feeding place after experiencing aggressive encounters. In this paper, we show that, at the individual level, the aphid-tending ant Lasius niger reacts to the presence of an alien conspecific through direct aggressive behavior and local recruitment in the vicinity of fights. At the colony level, however, no defensive recruitment is triggered and the “risky” area where aggressive encounters occur is not specifically avoided during further exploration or food exploitation. We discuss how between-species differences in sensitivity to interference competition could be related to the spatial and temporal predictability of food resources at stake. 1. Introduction Competition is generally considered as the major force structuring patterns of distribution and abundance in ant communities [1–4]. Both competition by exploitation and competition by interference can be found in ants. Exploitative competition is defined as the capacity for one species, one group, or one individual to find and exploit rapidly a potentially limited resource, thereby making it unavailable to competitors. Competition by interference on the other hand is defined as the capacity to prevent physical access to a resource, either directly by disturbing or attacking other foragers or indirectly, by delimiting a territory and excluding competitors from foraging sites [5]. Interference competition is particularly widespread in ants. Indeed, many ant species show some forms of territoriality [6, 7], and workers from one colony readily attack intruders from other colonies of the same [3, 8] or of a different species [9, 10]. The level of aggression displayed during interference encounters in ants can be tuned according to a variety of factors, including the species to which the competitor belongs [11, 12], the degree of familiarity with the competitor [7, 13–17], and the number of contestants [18–21] as well as the incurred risks in terms of energy/time loss, injury or even
The Tergal Gland Secretion of the Two Rare Myrmecophilous Species Zyras collaris and Z. haworthi (Coleoptera: Staphylinidae) and the Effect on Lasius fuliginosus  [PDF]
Michael Stoeffler,Lea Boettinger,Till Tolasch,Johannes L. M. Steidle
Psyche , 2013, DOI: 10.1155/2013/601073
Abstract: The beetle species Zyras collaris and Z. haworthi belong to the rove beetle tribe Myrmedoniini (Staphylinidae: Aleocharinae), which comprises many myrmecophilous species. Due to their rareness, it is unknown how the two species interact with their host ants. GC-MS analyses revealed that both species release α-pinene, β-pinene, myrcene and limonene from their defensive tergal glands. This composition of tergal gland secretion is unique within the subfamily Aleocharinae. In biotests, Lasius fuliginosus ants showed increased antennation towards filter paper balls treated with mixtures of these substances in natural concentrations. Because these monoterpenes are also present in some aphid species which are attended by ants, we hypothesize that Zyras beetles mimic the presence of aphids and thereby achieve acceptance by their host ants. 1. Introduction The rove beetles tribe Myrmedoniini (Staphylinidae: Aleocharinae) contains many myrmecophilous species. In Central Europe, it comprises the myrmecophilous genera Lomechusa and Lomechusoides, Zyras, Myrmoecia, and Pella, as well as the nonmyrmecophilous species Drusilla canaliculata Fabricius, 1787. Myrmoecia and Pella were formerly considered subgenera of Zyras but, meanwhile, have been elevated to genus rank [1–3], which is also supported by molecular data [4, 5]. Lomechusa and Lomechusoides are textbook examples for the integration of myrmecophiles in ant nests by the use of appeasement glands on their abdomen [6]. Different strategies are used by Pella species to escape from aggressions by their host ant Lasius fuliginosus (Latreille, 1798). While the Japanese species P. comes (Sharp, 1874) mimics the cuticular hydrocarbon (CHC) pattern of its host ant to be accepted [7], P. laticollis (M?rkel, 1845) employs a specific appeasing behaviour [8]. Pella cognata (M?rkel, 1842), P. funesta (Gravenhorst, 1806), and P. humeralis (Gravenhorst, 1802) repel ants by the use of their abdominal tergal gland. This tergal gland is only found within the Aleocharinae and is used by most species of the subfamily as defensive gland against aggressors [9]. In P. funesta and P. humeralis, the gland secretion specifically contains sulcatone, a panic alarm inducing pheromone of L. fuliginosus. By the release of this compound, beetles create an “ant free space” [8, 10]. In contrast to these species, only little is known on the biology of Zyras species, and it is unclear how they achieve acceptance by ants. For Z. collaris (Paykull, 1789) and Z. haworthi (Stephens, 1835), this is mainly due to their rarity. For South-West Germany,
How Do Ants Make Sense of Gravity? A Boltzmann Walker Analysis of Lasius niger Trajectories on Various Inclines  [PDF]
Ana?s Khuong, Valentin Lecheval, Richard Fournier, Stéphane Blanco, Sébastian Weitz, Jean-Jacques Bezian, Jacques Gautrais
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076531
Abstract: The goal of this study is to describe accurately how the directional information given by support inclinations affects the ant Lasius niger motion in terms of a behavioral decision. To this end, we have tracked the spontaneous motion of 345 ants walking on a 0.5×0.5 m plane canvas, which was tilted with 5 various inclinations by rad ( data points). At the population scale, support inclination favors dispersal along uphill and downhill directions. An ant's decision making process is modeled using a version of the Boltzmann Walker model, which describes an ant's random walk as a series of straight segments separated by reorientation events, and was extended to take directional influence into account. From the data segmented accordingly ( segments), this extension allows us to test separately how average speed, segments lengths and reorientation decisions are affected by support inclination and current walking direction of the ant. We found that support inclination had a major effect on average speed, which appeared approximately three times slower on the incline. However, we found no effect of the walking direction on speed. Contrastingly, we found that ants tend to walk longer in the same direction when they move uphill or downhill, and also that they preferentially adopt new uphill or downhill headings at turning points. We conclude that ants continuously adapt their decision making about where to go, and how long to persist in the same direction, depending on how they are aligned with the line of maximum declivity gradient. Hence, their behavioral decision process appears to combine klinokinesis with geomenotaxis. The extended Boltzmann Walker model parameterized by these effects gives a fair account of the directional dispersal of ants on inclines.
Parasitism, the diversity of life, and paleoparasitology
Araújo, Adauto;Jansen, Ana Maria;Bouchet, Fran?oise;Reinhard, Karl;Ferreira, Luiz Fernando;
Memórias do Instituto Oswaldo Cruz , 2003, DOI: 10.1590/S0074-02762003000900003
Abstract: the parasite-host-environment system is dynamic, with several points of equilibrium. this makes it difficult to trace the thresholds between benefit and damage, and therefore, the definitions of commensalism, mutualism, and symbiosis become worthless. therefore, the same concept of parasitism may encompass commensalism, mutualism, and symbiosis. parasitism is essential for life. life emerged as a consequence of parasitism at the molecular level, and intracellular parasitism created evolutive events that allowed species to diversify. an ecological and evolutive approach to the study of parasitism is presented here. studies of the origin and evolution of parasitism have new perspectives with the development of molecular paleoparasitology, by which ancient parasite and host genomes can be recovered from disappeared populations. molecular paleoparasitology points to host-parasite co-evolutive mechanisms of evolution traceable through genome retrospective studies.
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