Apterygota special issue of the European Journal of Soil Biology

Zoologica Scripta, 2000

The phylogenetic interrelation-ships of the higher taxa of apterygote hexapods. -Zoologica Scripta, 29, 131-156. The phylogeny of the basal hexapods, the so-called apterygote insects, was studied using parsimony analysis procedures. Most analyses took into account 47 characters mainly based on external morphology, and 19 taxa including 14 apterygote representatives, 3 pterygotes and also 2 distantly related myriapods were used as outgroups. The binary and multistate characters are discussed in detail and treated as unordered and equally weighted. Other analyses were performed using a second data set in which 28 characters, based on internal anatomy and already used in a previous work , were added to the first data set. This second matrix was restricted to 12 terminal taxa, the same as those of our previous work. The results of the different analyses are generally congruent. They strongly support the monophyly of several orders (Protura, Collembola, Archaeognatha) and of two groupings (Ectognatha, Dicondylia). Three other assemblages (Ellipura, Diplura, Entognatha) appear as parsimonious phylogenetic hypotheses, but they are never supported by the cladistical analyses and are based on a very small number of autapomorphies; so, the monophyly of each of them is not firmly established. Archaeognatha appears as the sister group of the Dicondylia. The three unresolved representatives of the Zygentoma are found as the sister group of the Pterygota. The results are discussed in the light of current concepts in hexapod phylogeny.

European Journal of Soil Biology, 2008

Wingless basal hexapods, also known as Apterygota, are becoming more and more important as models to study general biological principles, a situation testified by papers presented at the VIIth Apterygota seminar held August 2006 at Texel, The Netherlands. In this short review we discern three areas of modern biology where Apterygota may obtain a position in the spotlight: (1) ecology: Apterygota communities can contribute to testing hypotheses about species traits, community composition and ecosystem function, (2) evolution: Apterygota are a crucial link in the deep phylogeny of the arthropods, (3) genomics: transcription profiling of apterygote model species can contribute to soil assessment and a better mechanistic understanding of how soil invertebrates may adapt to soil pollution. We describe these three areas and the exciting developments going on in each.

Pedobiologia, 2006

Molecular data have been increasingly used to study the phylogenetic relationships among many animal taxa, including arthropods. Sometimes they have provided phylogenetic reconstructions that are in conflict with morphological data leading to a re-evaluation of long-standing evolutionary hypotheses. In this paper, we review the major contributions to the phylogeny of hexapods based on molecular data, with emphasis on the relationships of basal hexapod taxa. The placement and the monophyly of the five basal hexapod lineages (the ''apterygotes'': Protura, Collembola, Diplura, Microcoryphia and Zygentoma) are one of the hottest issues in arthropod phylogeny. We discuss methods of data collection and analysis, and we describe the areas of conflict and agreement between molecular phylogenies and the evidence provided by morphological characters.

2018

Pedobiologia, 2002

L La ab bo or ra at to or ry y o ob bs se er rv va at ti io on ns s o on n t th he e b bi io ol lo og gy y o of f X Xe en ny yl ll la a w we el lc ch hi i ( (C Co ol ll le em mb bo ol la a: :H He ex xa ap po od da a) ) Summary Egg batches of Xenylla welchi are laid in crevices, holes, exuviae, etc. In the present study, the total number of eggs per female varied between 134 and 148. The first batch of eggs was generally laid at the beginning of the sixth instar, on reaching of sexual maturity. The embryonic development was completed in 5 days at 26°C to 30°C, while it took 11 and 17 days at 20 ± 1°C and 15 ± 1°C, respectively. First instar animal usually hatched through a gradually widening slit in the exposed surface of the egg. Each moult was easily recognized by the presence of cast skin. The post-embryonic development was completed within 10.5 days at 26°C to 30°C and 20 days at 20 ± 1°C. The individual life span was 83 days on average, comprising 22 moults.

Science, 2003

Revista de la Facultad de Ciencias Agrarias , 2018

In order to evaluate the effects of the anthropic impact on the structure of de soil collembolan community, three different soil uses were researched: agricultural fields (AG) with 50 years of continuous farming, pastures entering the agricultural cycle (CG), and naturalized grasslands (NG). The study was carried out in fields of Chivilcoy (34°53\'49 S, 60°01\'09 W, elev. 60 m) and Navarro (34°51’30 S, 59°12’25 W, elev. 43 m), Buenos Aires Province, Argentina. For each of the three uses, three fields were selected as replicates, with three soil samples per replicate and sample date (10) for a total of 216 samples analyzed. Collembolans (Hexapoda: Collembola) were extracted and identified to family level. Five families were found: Hypogastruridae, Onychiuridae, Isotomidae, Entomobryidae, and Katiannidae. Soils were also characterized by means of physical and chemical analyses. The index of degree of change of collembolan diversity was calculated with the biological data. The results show that the biological index of degree of change can detect soil use effects on the collembolan community. Somewhat surprisingly, the index showed that the diversity of collembolans was higher in the high anthropic impact site AG, followed by CG and lowest in NG. The results also show that collembolan families respond differently to soil use. The families Hypogastruridae, Onychiuridae, and Isotomidae presented differences between systems. Therefore, collembolan community structure can be a useful tool to assess agricultural practices´ impacts on soil.

Pesquisa Agropecuaria Brasileira, 2010

The objective of this work was to elevate gradient effect on diversity of Collembola, in a temperate forest on the northeast slope of Iztaccíhuatl Volcano, Mexico. Four expeditions were organized from November 2003 to August 2004, at four altitudes (2,753, 3,015, 3,250 and 3,687 m a.s.l.). In each site, air temperature, CO 2 concentration, humidity, and terrain inclination were measured. The infl uence of abiotic factors on faunal composition was evaluated, at the four collecting sites, with canonical correspondence analyses (CCA). A total of 24,028 specimens were obtained, representing 12 families, 44 genera and 76 species. Mesaphorura phlorae, Proisotoma ca. tenella and Parisotoma ca. notabilis were the most abundant species. The highest diversity and evenness were recorded at 3,250 m (H' = 2.85; J' = 0.73). Canonical analyses axes 1 and 2 of the CCA explained 67.4% of the variance in species composition, with CO 2 and altitude best explaining axis 1, while slope and humidity were better correlated to axis 2. The results showed that CO 2 is an important factor to explain Collembola species assemblage, together with slope and humidity. Index terms: Collembola, canonical correspondence analysis, CO 2 , mesofauna communities, spatial variation. Diversidade de colêmbolos (Hexapoda) de acordo com o gradiente de altitude

Organisms Diversity & Evolution, 2004

Hexapoda includes 33 commonly recognized orders, most of them insects.Ongoi ng controversy concerns the grouping of Protura and Collembola as a taxon Ellipura, the monophyly of Diplura, a single or multiple origins of entognathy, and the monophyly or paraphyly of the silverfish (Lepidotrichidae and Zygentoma s.s.) with respect to other dicondylous insects.Here we analyze relationships among basal hexapod orders via a cladistic analysis of sequence data for five molecular markers and 189 morphological characters in a simultaneous analysis framework using myriapod and crustacean outgroups.Using a sensitivity analysis approach and testing for stability, the most congruent parameters resolve Tricholepidion as sister group to the remaining Dicondylia, whereas most suboptimal parameter sets group Tricholepidion with Zygentoma.Stable hypotheses include the monophyly of Diplura, and a sister group relationship between Diplura and Protura, contradicting the Ellipura hypothesis.Hexapod monophyly is contradicted by an alliance between Collembola, Crustacea and Ectognatha (i.e., exclusive of Diplura and Protura) in molecular and combined analyses.

Proceedings of the Royal Society B: Biological Sciences, 2005

Recent molecular analyses indicate that crustaceans and hexapods form a clade (Pancrustacea or Tetraconata), but relationships among its constituent lineages, including monophyly of crustaceans, are controversial. Our phylogenetic analysis of three protein-coding nuclear genes from 62 arthropods and lobopods (Onychophora and Tardigrada) demonstrates that Hexapoda is most closely related to the crustaceans Branchiopoda (fairy shrimp, water fleas, etc.) and Cephalocarida þ Remipedia, thereby making hexapods terrestrial crustaceans and the traditionally defined Crustacea paraphyletic. Additional findings are that Malacostraca (crabs, isopods, etc.) unites with Cirripedia (barnacles, etc.) and they, in turn, with Copepoda, making the traditional crustacean class Maxillopoda paraphyletic. Ostracoda (seed shrimp)-either all or a subgroup-is associated with Branchiura (fish lice) and likely to be basal to all other pancrustaceans. A Bayesian statistical (non-clock) estimate of divergence times suggests a Precambrian origin for Pancrustacea (600 Myr ago or more), which precedes the first unambiguous arthropod fossils by over 60 Myr.