Habitat associations of the Coastal Giant Salamander (Dicamptodon Tenebrosus) at its northern range limit

Knowledge of species-environment associations is critical for the management of threatened amphibian populations facing habitat fragmentation and a restricted range. The Coastal Giant Salamander (Dicamptodon tenebrosus) is subject to habitat degradation from logging and human development and is classified as Threatened at its northern range limit in British Columbia, Canada. We examined habitat associations for D. tenebrosus in relation to relative abundance and presence/absence for 32 streams sampled across the approximately 100 km range of the species in British Columbia. Of 12 environmental variables we measured at 100-m stream reaches and the adjacent riparian zone, D. tenebrosus relative abundance was positively associated with stream elevation, forest age, and the percentage of boulders within streams. A higher stream gradient was the best predictor of D. tenebrosus presence within a stream reach, with present sites having a 91% higher gradient than absent sites. When excluding sites with low relative abundance, D. tenebrosus presence was also predicted by greater forest age surrounding streams and higher site elevation. Our study highlights that conservation planning for stream-associated amphibians with patchy distributions may be improved by an understanding of species-specific habitat associations at the stream-reach scale

Taxonomic Shifts in <em>Philornis</em> Larval Behaviour and Rapid Changes in <em>Philornis downsi</em> Dodge & Aitken (Diptera: Muscidae): An Invasive Avian Parasite on the Galápagos Islands

The parasitic larvae of Philornis downsi Dodge & Aitken (Diptera: Muscidae) were first discovered in Darwin’s finch nests on the Galápagos Islands in 1997. Larvae of P. downsi consume the blood and tissue of developing birds, causing high in-nest mortality in their Galápagos hosts. The fly has been spreading across the archipelago and is considered the biggest threat to the survival of Galápagos land birds. Here, we review (1) Philornis systematics and taxonomy, (2) discuss shifts in feeding habits across Philornis species comparing basal to more recently evolved groups, (3) report on differences in the ontogeny of wild and captive P. downsi larvae, (4) describe what is known about adult P. downsi behaviour, and (5) discuss changes in P. downsi behaviour since its discovery on the Galápagos Islands. From 1997 to 2010, P. downsi larvae have been rarely detected in Darwin’s finch nests with eggs. Since 2012, P. downsi larvae have regularly been found in the nests of incubating Darwin’s finches. Exploring P. downsi ontogeny and behaviour in the larger context of taxonomic relationships provides clues about the breadth of behavioural flexibility that may facilitate successful colonisation

Signatures of local adaptation along environmental gradients in a range-expanding damselfly (Ischnura elegans)

ACKNOWLEDGEMENTSThis work was supported by an EU FP7, Marie Curie International Incoming Fellowship (to RYD; project code “MOVE2ADAPT”), a Wenner-Gren Foundation Postdoctoral Stipend (to RYD), the Oscar and Lili Lamm Foundation (to RYD, BH), Biodiversity and Ecosystem Services in a Changing Climate (BECC; a joint Lund–Gothenburg University initiative) (LL), the Swedish Research Council (EIS, BH),the Crafoord Foundation (EIS, BH) and Erik Philip-Sorensens Stiftelse (E.I.S.). We would like to thank Hanna Bensch and Paul Caplat for assistance with the collection of samples in the field and the Grimso Research Station and Mikael Akesson for logistical support. Wethank Pallavi Chauhan for assistance with SNP annotation. We thank Martin Andersson for assistance with DNA extraction, Jane Jonssonfor laboratory administration, and Julian Catchen, Martin Stervander, Dag Ahren and Maren Wellenreuther for bioinformatics advice and helpful discussion.Peer reviewedPostprin

Latitudinal clines in sexual selection, sexual size dimorphism, and sex-specific genetic dispersal during a poleward range expansion

Acknowledgements This work was supported by Macquarie University (to AC, RYD), an EU FP7, Marie Curie International Incoming Fellowship (to RYD, BH; project code ‘MOVE2ADAPT’), a WennerGren Foundation Postdoctoral Stipend (to RYD, BH), the Oscar and Lili Lamm Foundation (to RYD, BH), Biodiversity and Ecosystem Services in a Changing Climate (BECC; a joint LundGothenburg University initiative) (to LL, BH), the Swedish Research Council (to EIS, BH (2014-5222, 2016-689)), the Crafoord Foundation, “Stina Werners Stiftelse” and “Erik Philip Sörensens Stiftelse” (to EIS). We thank Hanna Bensch, John Waller, Paul Caplat and Martin Andersson for field and lab assistance, the Grimsö Research Station and Mikael Åkesson for field support and Sonu Yadav for analysis advice. We thank Julian Catchen, Martin Stervander and Dag Ahren for bioinformatics advice and Maren Wellenreuther for helpful discussion.Peer reviewedPostprin

Genomic divergence and a lack of recent introgression between commercial and wild bumblebees (Bombus terrestris)

The global movement of bees for agricultural pollination services can affect local pollinator populations via hybridization. When commercial bumblebees are of the same species but of different geographic origin, intraspecific hybridization may result in beneficial integration of new genetic variation, or alternatively may disrupt locally adapted gene complexes. However, neither the existence nor the extent of genomic introgression and evolutionary divergence between wild and commercial bumblebees is fully understood. We obtained whole-genome sequencing data from wild and commercial Bombus terrestris collected from sites in Southern Sweden with and without long-term use of commercially imported B. terrestris. We search for evidence of introgression, dispersal and genome-wide differentiation in a comparative genomic analysis of wild and commercial bumblebees. Commercial B. terrestris were found in natural environments near sites where commercial bumblebees were used, as well as drifting wild B. terrestris in commercial bumblebee colonies. However, we found no evidence for widespread, recent genomic introgression of commercial B. terrestris into local wild conspecific populations. We found that wild B. terrestris had significantly higher nucleotide diversity (Nei's pi, pi), while the number of segregating sites (Watterson's theta, theta w) was higher in commercial B. terrestris. A highly divergent region on chromosome 11 was identified in commercial B. terrestris and found to be enriched with structural variants. The genes present in this region are involved in flight muscle contraction and structure and pathogen immune response, providing evidence for differing evolutionary processes operating in wild and commercial B. terrestris. We did not find evidence for recent introgression, suggesting that co-occurring commercial B. terrestris have not disrupted evolutionary processes in wild B. terrestris populations

Current and Historical Drivers of Landscape Genetic Structure Differ in Core and Peripheral Salamander Populations

With predicted decreases in genetic diversity and greater genetic differentiation at range peripheries relative to their cores, it can be difficult to distinguish between the roles of current disturbance versus historic processes in shaping contemporary genetic patterns. To address this problem, we test for differences in historic demography and landscape genetic structure of coastal giant salamanders (Dicamptodon tenebrosus) in two core regions (Washington State, United States) versus the species' northern peripheral region (British Columbia, Canada) where the species is listed as threatened. Coalescent-based demographic simulations were consistent with a pattern of post-glacial range expansion, with both ancestral and current estimates of effective population size being much larger within the core region relative to the periphery. However, contrary to predictions of recent human-induced population decline in the less genetically diverse peripheral region, there was no genetic signature of population size change. Effects of current demographic processes on genetic structure were evident using a resistance-based landscape genetics approach. Among core populations, genetic structure was best explained by length of the growing season and isolation by resistance (i.e. a ‘flat’ landscape), but at the periphery, topography (slope and elevation) had the greatest influence on genetic structure. Although reduced genetic variation at the range periphery of D. tenebrosus appears to be largely the result of biogeographical history rather than recent impacts, our analyses suggest that inherent landscape features act to alter dispersal pathways uniquely in different parts of the species' geographic range, with implications for habitat management

Love thy neighbour? Social nesting pattern, host mass and nest size affect ectoparasite intensity in Darwin's tree finches

Social nesting behaviour is commonly associated with high prevalence and intensity of parasites in intraspecific comparisons. Little is known about the effects of interspecific host breeding density for parasite intensity in generalist host-parasite systems. Darwin's small tree finch (Camarhynchus parvulus) on Santa Cruz Island, Galápagos Islands, nests in both heterospecific aggregations and at solitary sites. All Darwin finch species on Santa Cruz Island are infested with larvae of the invasive blood-sucking fly Philornis downsi. In this study, we test the prediction that total P. downsi intensity (the number of parasites per nest) is higher for nests in heterospecific aggregations than at solitary nests. We also examine variation in P. downsi intensity in relation to three predictor variables: (1) nest size, (2) nest bottom thickness and (3) host adult body mass, both within and across finch species. The results show that (1) total P. downsi intensity was significantly higher for small tree finch nests with many close neighbours; (2) finches with increased adult body mass built larger nests (inter- and intraspecific comparison); (3) parasite intensity increased significantly with nest size across species and in the small tree finch alone; and (4) nest bottom thickness did not vary with nest size or parasite intensity. These results provide evidence for an interaction between social nesting behaviour, nest characteristics and host mass that influences the distribution and potential impact of mobile ectoparasites in birds.9 page(s

Blood and intestinal parasitism in Darwin's finches : negative and positive findings

Darwin’s finches are an iconic bird group that has transformed our perception of evolutionary dynamics in wild populations. Surprisingly, the parasites and diseases of these finches are virtually unstudied. This study simultaneously investigates blood and intestinal parasitism in Darwin’s Small Ground Finch Geospiza fuliginosa and intestinal parasitism in the Medium Ground FinchGeospiza fortis. We sampled 127 adults for blood parasites and 22 nestlings for blood and intestinal parasites across three islands, Santa Cruz, Isabela, and Floreana, in the Galapagos Archipelago. We found no evidence of blood parasites in G. fuliginosa and no evidence of intestinal parasitism in G. fortis. On Floreana, one G. fuliginosa nestling was identified with an intestinal parasite of the genus Isospora, which is the first record for this island.6 page(s

11408_snps_Pvitt

Map file containing 11,408 SNP loci name