Spider Assemblages across Elevational and Latitudinal Gradients in the Yukon Territory, Canada

Arthropod assemblages in the Arctic are set for substantial changes in response to climate change, yet we know little about the ecological structure of many groups in the North. We tested the effects of elevation and latitude on northern spider assemblages by sampling along nine mountains across three latitudes in the Yukon Territory, Canada. Spiders were collected in 216 pitfall traps placed at four elevations along each of the nine mountains, representing 36 sites sampled across three latitudes (i.e., distinct mountain ranges). We collected 1954 individuals representing 89 species, 57 genera, and 12 families of spiders. Using nested ANOVAs, we found significant main effects of latitude, elevation, and an interaction of the two factors on species richness and abundance. Using MRPP and NMS ordination, we also found significant effects of latitude and mountain on species composition, but within each of the three latitudes, only elevation produced significant effects. Our study suggests that changes along spatial gradients associated with changes in habitat can have significant effects on the structure of spider assemblages, but responses vary among mountain ranges. We show that within a given mountain range, individual mountains may be used as spatial replicates for studies about northern arthropod assemblages.Les assemblages d’arthropodes de l’Arctique connaîtront des changements substantiels en raison du changement climatique mais malgré cela, nous en savons peu sur la structure écologique de nombreux groupes du Nord. Nous avons mis à l’épreuve les effets de l’élévation et de la latitude sur les assemblages d’araignées du Nord en prélevant des échantillons sur neuf montagnes réparties sur trois latitudes dans le territoire du Yukon, au Canada. Les araignées ont été recueillies à l’aide de 216 pièges placés à quatre élévations différentes le long de chacune des neuf montagnes, ce qui a représenté 36 emplacements échantillonnés sur trois latitudes (c’est-à-dire des chaînes de montagnes distinctes). Nous avons recueilli 1 954 individus représentant 89 espèces, 57 genres et 12 familles d’araignées. À l’aide d’analyses de variances (ANOVA), nous avons relevé d’importants effets découlant de la latitude, de l’élévation et de l’interaction de deux facteurs sur la richesse et l’abondance des espèces. Au moyen de l’ordination MRPP et NMS, nous avons également constaté que la latitude et la montagne ont des incidences considérables sur la composition des espèces, mais au sein de chacune des trois latitudes, seule l’élévation produisait des effets importants. Notre étude laisse entendre que les changements en matière de gradients spatiaux liés aux changements d’habitat peuvent avoir des effets considérables sur la structure d’assemblages d’araignées, mais les réactions varient d’une chaîne de montagne à l’autre. Nous montrons que dans une chaîne de montagne donnée, les montagnes individuelles peuvent servir de mesures spatiales en vue de l’étude d’assemblages d’arthropodes nordiques

Spiders from the Island of Fernando de Noronha, Brazil: Part III: Gnaphosidae (Araneae: Arachnida)

The female of Zimiromus hortenciae Buckup & Brescovit, 1993 is described for the first time and Trachyzelotes kulczynskii (Bösemberg, 1902), a species introduced from Europe, is recorded for the first time on the island of Fernando de Noronha, state of Pernambuco. The latter, along with T. lyonneti (Audouim, 1826) recorded from the state of Rio Grande do Sul, is the second species of this genus to be reported from Brazil. The spiders were collected with pitfall traps in five points of the island. Ecological data showed that Gnaphosidae was the fifth best sampled spider family, with 179 specimens, belonging to two species, T. kulczynskii and Z. hortenciae. Trachyzelotes kulczynskii was the most abundant with 118 adults while Z. hortenciae was represented by only 21 adults. Both species were collected during the dry and wet seasons but T. kulczynskii was more abundant during the wet season while Z. hortenciae was more abundant during the dry season. The male:female ratio for the dry season was similar for both species but in the wet season it was three times higher for T. kulczynskii.<br>A fêmea de Zimiromus hortenciae Buckup & Brescovit, 1993 é descrita pela primeira vez. Trachyzelotes kulczynskii (Bösemberg, 1902), uma espécie de origem européia, é registrada pela primeira vez na Ilha de Fernando de Noronha, no estado de Pernambuco. Junto com T. lyonneti (Audouin, 1826), já registrado para o estado do Rio Grande do Sul, Brasil, é a segunda espécie do gênero introduzida no Brasil. As aranhas foram coletadas com armadilhas de solo em cinco pontos da ilha e os dados ecológicos detectados para Gnaphosidae foram de que esta foi a quinta família melhor amostrada dentre Araneae, com 179 espécimes de duas espécies, T. kulczynskii e Z. hortenciae. Trachyzelotes kulczynskii foi mais abundante com 118 adultos enquanto Z. hortenciae teve 21 adultos coletados. Ambas foram coletadas nas estações seca e chuvosa, sendo que T. kulczynskii foi mais abundante na estação chuvosa enquanto Z. hortenciae o foi na estação seca. A proporção de machos e fêmeas foi similar na estação seca, mas na estação chuvosa a proporção de T. kulczynskii foi três vezes maior