/pdf/an-introduction-to-the-aquatic-insects-of-north-america-20i7stzjkw.pdf

An Introduction to the Aquatic Insects of North America

THE author of this book ranks as the foremost American worker on insect morphology. His contributions on the subject are notable for their clarity and originality of thought, and the appearance of a volume, embodying his ideas in comprehensive form, is sure of a hearty welcome. In its preparation, Mr. Snodgrass has incorporated the results of much first-hand study with those of many recent investigators in the same field. He has produced an outstanding book wherein knowledge of facts is combined with that of function and, at the same time, theoretical conceptions of the origins and relationships of organs and parts are not overlooked. Principles of Insect Morphology
 By R. E. Snodgrass. (McGraw-Hill Publications in the Zoological Sciences.) Pp. ix + 667. (New York and London: McGraw-Hill Book Co., Inc., 1935.) 36s. net.

Principles of Insect Morphology

. In order to infer phylogenetic relationships within the extraordinarily speciesrich order Coleoptera, a cladistic analysis is performed, in which 516 adult and larval morphological characters are scored for 359 beetle taxa, representing 314 families or subfamilies plus seven outgroup taxa representing seven holometabolan orders. Many morphological features are discussed at length with accompanying illustrations, and an attempt is made to homologize these and employ a uniform set of terms throughout the order. The resulting data matrix is analyzed using the parsimony ratchet in conjunction with implied weighting. The resulting most parsimonious tree found the order Strepsiptera to be sister to Coleoptera, each of the four coleopteran suborders to be monophyletic and subordinal relationships as follows: (Archostemata + Adephaga) + (Myxophaga + Polyphaga), but without significant support for either clade. The topology of the remainder of the tree is consistent with many prior molecular and morpholo...

/pdf/phylogeny-of-the-coleoptera-based-on-morphological-y0p029sey9.pdf

Phylogeny of the Coleoptera Based on Morphological Characters of Adults and Larvae

With almost 40 000 species, the spiders provide important model systems for studies of sociality, mating systems, and sexual dimorphism. However, work on this group is regularly constrained by diff...

Identifying spiders through DNA barcodes

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/pdf/adapting-to-climate-change-a-perspective-from-evolutionary-qhfvxiwi1t.pdf

Adapting to climate change: a perspective from evolutionary physiology

In this study, we showed that selenium (Se) deposition from metal smelters in Sudbury, Ontario, greatly re- duces the bioassimilation of mercury (Hg) by aquatic biota throughout the food web. Concentrations of total and methyl mercury in tissues of zooplankton, mayflies (Stenonema femoratum), amphipods (Hyalella azteca), and young- of-the-year perch (Perca flavescens) were positively correlated with increasing distance from Sudbury smelters and inversely correlated with Se concentrations in lake water. Although concentrations of total Hg and total Se in tissues showed weak or no correlation in most of the studied aquatic species, methyl mercury and total Se showed much clearer inverse trends. Similar to the results of our previous study of muscle tissue from adult perch and walleye (Sander vitreus), these findings suggest that Se plays an important role in limiting the whole-body assimilation of Hg at lower levels of the aquatic food chain. High Se concentrations may force a preferential assimilation of the element over Hg through a competitive adsorption on binding sites. They may also restrict the solubility and availability of Hg to aquatic organisms or reduce the methylation of this metal in lakes. Resume : Nous montrons dans cette etude que la deposition de selenium (Se) provenant des hauts fourneaux de Sud- bury en Ontario reduit grandement l'assimilation du mercure (Hg) par le biote aquatique tout au long de la chaine alimentaire. Les concentrations en Hg total et methylmercure dans les tissus de zooplancton, ephemeres (Stenonema femoratum), amphipodes (Hyalella azteca) et jeunes perchaudes (Perca flavescens) de l'annee ont pu etre directement correlees avec la distance qui les separe des hauts fourneaux de Sudbury et inversement correlees avec les concentra- tions de Se dans l'eau de lac. Alors que les concentrations en Hg total et Se total dans les tissus ne montrent que des correlations faibles ou nulles entre elles chez la plupart des organismes etudies, le methylmercure et le Se total mon- trent des relations inverses beaucoup plus claires. De facon similaire aux resultats de notre etude precedente sur les tissus musculaires de perchaudes et de dores (Sander vitreus) adultes, ces donnees laissent croire que le Se joue un role important en limitant l'assimilation integrale du Hg aux niveaux inferieurs de la chaine alimentaire aquatique. Les fortes concentrations de Se pourraient conduire a une assimilation preferentielle de cet element sur celle du Hg a travers une adsorption competitive sur des sites de liaison. Elles pourraient aussi restreindre la solubilite et la disponi- bilite du mercure chez les organismes aquatiques ou reduire la methylation de ce metal dans les lacs.

The effect of selenium on mercury assimilation by freshwater organisms

Insect life stages are known imperfectly in many cases, and classifications are based often on only one or a few semaphoronts of a species. This is unfortunate as information in alternative life stages often is useful for scientific study. Although recent examples of DNA in taxonomy have emphasized the identification of indistinguishable species, such sequence data facilitate the association of life history stages and hold considerable promise in phylogenetic analysis, evolutionary studies, diagnostics, etc. These concepts are discussed here and an example is provided from diving beetles (Dytiscidae: Coleoptera). Three unknown larval specimens of an apparent species of Laccophilinae collected in Namibia were associated with the species Philodytes umbrinus (Motschulsky) using DNA sequence data. An 806-bp portion of the gene cytochrome oxidase I was sequenced from the unknown larvae. Several identified adult specimens of species of Laccophilinae from Namibia were also sequenced, including two P. umbrinus specimens and specimens from four Laccophilus Leach species. Additional species of Laccophilus from other areas of the world also were sequenced, as were specimens of Agabetes acuductus (Harris), Australphilus saltus Watts, Neptosternus boukali Hendrich & Balke and a species of Laccodytes Regimbart. Parsimony analysis resulted in two most parsimonious trees with the unknown larva unambiguously resolved in a group with both adult specimens of P. umbrinus (bootstrap value = 100%). The average pairwise p-distance between the unknown larva and adult P. umbrinus specimens averaged 0.09% (0-0.14%), compared with an average divergence between other conspecifics in the analysis of 0.24% (0-0.82%) and an overall average divergence between species of 13.49% (1.90-19.86%). Based on this, the unknown larvae were assigned to P. umbrinus. The larvae are diagnosed and described and their relationship with other Laccophilinae is discussed.

Association of insect life stages using DNA sequences: the larvae of Philodytes umbrinus (Motschulsky) (Coleoptera: Dytiscidae)

Regional acidification of aquatic habitats has caused severe reductions in biodiversity. Reduced sulfur dioxide emissions over the past several decades have resulted in increased pH and alkalinity in some areas of North America and Europe. However, biological recovery has lagged behind increases in lake pH. We propose that acidification-induced changes in predator assemblages can provide biological resistance to recovery of assemblages in lower trophic levels in lakes. Many recovering lakes remain fishless because of low colonization rates and, therefore, support a high abundance of macroinvertebrate predators that may have a large impact on zooplankton community structure. We assessed the distribution of water beetles in relation to pH and presence/absence of fish in 29 lakes on the Canadian Shield. We found that water beetle assemblage composition was not related to pH. However, the occurrence of fish was significantly negatively correlated with water beetle distribution, particularly for the pr...

https://www.jstor.org/stable/10.1899/0887-3593(2006)025%5B0811:DAPEOW%5D2.0.CO;2

Distribution and potential effects of water beetles in lakes recovering from acidification

Through an analysis of the primary setae and pores (campaniform sensilla) of first-instar larvae of 32 species of Colymbetinae, 33 species belonging to other dytiscid subfamilies, and seven species belonging to other families of Hydradephaga, the ancestral system of primary setae and pores of the legs, the last abdominal segment, and the urogomphi of Colymbetinae is deduced. Seventy-four setae and 24 pores have been assigned to the generalized colymbetine larva: 51 setae and 18 pores on the legs, 15 setae and three pores on the last abdominal segment, and eight setae and three pores on each urogomphus. A comparison with the ground-plan pattern of the subfamily Hydroporinae is provided. Members of Colymbetinae differ from those of Hydroporinae by the presence of setae TR3, AB14, and AB15, the absence of pore ABd, and the presence of a variable number of additional setae on the femur. A tentative phylogenetic reconstruction of the colymbetine genera provided is based on 24 larval characteristics. The monophyletic origin of the subfamily Colymbetinae is confirmed based on the shared presence of seta AB14. Two monophyletic lineages unite basally: (1) [(Agabus Leach + Ilybius Erichson) + Agabinus Crotch], and (2) {[Colymbetes Clairville + (Rhantus Dejean + Neoscutopterus Balfour-Browne)] + Matus Aube}. The genera Agabinus and Matus are postulated as a sister-group of (Agabus + Ilybius) and [(Colymbetes + (Rhantus + Neoscutopterus)], respectively. Compared with other Colymbetinae, both Neoscutopterus and Matus stand out by the presence of several strikingly peculiar features. The subgenus Rhantus (Nartus) is postulated to be the sister-group of Neoscutopterus based on the shared presence of additional setae on the dorsal margin of the femur.

Primary setae and pores on the legs, the last abdominal segment, and the urogomphi of larvae of Nearctic Colymbetinae (Coleoptera: Adephaga: Dytiscidae) with an analysis of their phylogenetic relationships

The first instar larvae of 24 North American species of Hydroporinae (Coleoptera: Dytiscidae), 6 species belonging to the three other dytiscid subfamilies, and 2 species each of Amphizoidae and Hyg...

Primary setae and pores on the last abdominal segment and the urogomphi of larval Hydroporinae (Coleoptera: Adephaga: Dytiscidae), with notes on other dytiscid larvae

Yves Alarie

Papers

The effect of selenium on mercury assimilation by freshwater organisms

Association of insect life stages using DNA sequences: the larvae of Philodytes umbrinus (Motschulsky) (Coleoptera: Dytiscidae)

Distribution and potential effects of water beetles in lakes recovering from acidification

Primary setae and pores on the legs, the last abdominal segment, and the urogomphi of larvae of Nearctic Colymbetinae (Coleoptera: Adephaga: Dytiscidae) with an analysis of their phylogenetic relationships

Primary setae and pores on the last abdominal segment and the urogomphi of larval Hydroporinae (Coleoptera: Adephaga: Dytiscidae), with notes on other dytiscid larvae