Multiple plant traits shape the genetic basis of herbivore community assembly

1. Community genetics research has posited a genetic basis to the assembly of ecological communities. For arthropod herbivores in particular, there is strong support that genetic variation in host plants is a key factor shaping their diversity and composition. However, the specific plant phenotypes underlying herbivore responses remain poorly explored for most systems. 2. We address this knowledge gap by examining the influence of both genetic and phenotypic variation in a dominant host-plant species, Salix hookeriana, on its associated arthropod herbivore community in a common garden experiment. Specifically, we surveyed herbivore responses among five different arthropod feeding guilds to 26 distinct S. hookeriana genotypes. Moreover, we quantified the heritability of a suite of plant traits that determine leaf quality (e.g. phenolic compounds, trichomes, specific leaf area, C : N) and whole-plant architecture, to identify which traits best accounted for herbivore community responses to S. hookeriana genotype. 3. We found that total herbivore abundance and community composition differed considerably among S. hookeriana genotypes, with strong and independent responses of several species and feeding guilds driving these patterns. We also found that leaf phenolic chemistry displayed extensive heritable variation, whereas leaf physiology and plant architecture tended to be less heritable. Of these traits, herbivore responses were primarily associated with leaf phenolics and plant architecture; however, different herbivore species and feeding guilds were associated with different sets of traits. Despite our thorough trait survey, plant genotype remained a significant predictor of herbivore responses in most trait association analyses, suggesting that unmeasured host-plant characteristics and/or interspecific interactions were also contributing factors. 4. Taken together, our results support that the genetic basis of herbivore community assembly occurs through a suite of plant traits for different herbivore species and feeding guilds. Still, identifying these phenotypic mechanisms requires measuring a broad range of plant traits and likely further consideration of how these traits affect interspecific interactions.Fil: Barbour, Matthew A.. University Of British Columbia; CanadáFil: Rodriguez Cabal, Mariano Alberto. University Of British Columbia; Canadá. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue; ArgentinaFil: Wu, Elizabeth T.. Humboldt State University; Estados UnidosFil: Julkunen Tiitto, Riitta. University of Eastern Finland; FinlandiaFil: Ritland, Carol E.. University Of British Columbia; CanadáFil: Miscampbell, Allyson E.. University Of British Columbia; CanadáFil: Jules, Erik S.. Humboldt State University; Estados UnidosFil: Crutsinger, Gregory M.. University Of British Columbia; Canad

Multiple Mating and Family Structure of the Western Tent Caterpillar, Malacosoma californicum pluviale: Impact on Disease Resistance

Background Levels of genetic diversity can strongly influence the dynamics and evolutionary changes of natural populations. Survival and disease resistance have been linked to levels of genetic diversity in eusocial insects, yet these relationships remain untested in gregarious insects where disease transmission can be high and selection for resistance is likely to be strong. Methodology/Principal Findings Here we use 8 microsatellite loci to examine genetic variation in 12 families of western tent caterpillars, Malacosoma californicum pluviale from four different island populations to determine the relationship of genetic variability to survival and disease resistance. In addition these genetic markers were used to elucidate the population structure of western tent caterpillars. Multiple paternity was revealed by microsatellite markers, with the number of sires estimated to range from one to three per family (mean ± SE = 1.92±0.23). Observed heterozygosity (HO) of families was not associated to the resistance of families to a nucleopolyhedrovirus (NPV) (r = 0.161, F1,12 = 0.271, P = 0.614), a major cause of mortality in high-density populations, but was positively associated with larval survival (r = 0.635, F1,10 = 5.412, P = 0.048). Genetic differentiation among the families was high (FST = 0.269, P<0.0001), and families from the same island were as differentiated as were families from other islands. Conclusion/Significance We have been able to describe and characterize 8 microsatellite loci, which demonstrate patterns of variation within and between families of western tent caterpillars. We have discovered an association between larval survival and family-level heterozygosity that may be relevant to the population dynamics of this cyclic forest lepidopteran, and this will be the topic of future work

Data from: Reduced genetic diversity and increased dispersal in Guigna (Leopardus guigna) in Chilean fragmented landscapes

Landscape fragmentation is often a major cause of species extinction as it can affect a wide variety of ecological processes. The impact of fragmentation varies among species depending on many factors, including their life-history traits and dispersal abilities. Felids are one of the groups most threatened by fragmented landscapes because of their large home ranges, territorial behavior, and low population densities. Here, we model the impacts of habitat fragmentation on patterns of genetic diversity in the guigna (Leopardus guigna), a small felid that is closely associated with the heavily human-impacted temperate rainforests of southern South America. We assessed genetic variation in 1798 base pairs of mitochondrial DNA sequences, 15 microsatellite loci, and 2 sex chromosome genes and estimated genetic diversity, kinship, inbreeding, and dispersal in 38 individuals from landscapes with differing degrees of fragmentation on Chiloé Island in southern Chile. Increased fragmentation was associated with reduced genetic diversity, but not with increased kinship or inbreeding. However, in fragmented landscapes, there was a weaker negative correlation between pairwise kinship and geographic distance, suggesting increased dispersal distances. These results highlight the importance of biological corridors to maximize connectivity in fragmented landscapes and contribute to our understanding of the broader genetic consequences of habitat fragmentation, especially for forest-specialist carnivores

Mitochondrial DNA sequences

File may be viewed using ProSeq software at http://dps.plants.ox.ac.uk/sequencing/proseq.htm [Filatov DA (2009) Processing and population genetic analysis of multigenic datasets with ProSeq3 software. Bioinformatics 25: 3189-3190]

Molecular phylogeny of an ancient rodent family (Aplodontiidae)

The family Aplodontiidae contains a single, monotypic extant genus, Aplodontia (mountain beaver), which was first described by Rafinesque in 1817. Phylogenetic studies have shown that it is the sister lineage to squirrels. Aplodontia rufa is endemic to the Pacific Northwest and ranges from central California to British Columbia, Canada. Currently, 7 described subspecies are recognized based on morphological taxonomic studies. In this study, mitochondrial and nuclear genes were sequenced to infer molecular phylogenies of A. rufa. One of the goals of this study was to use molecular data to test the current taxonomic hypothesis based on morphology. Another goal was to incorporate geographic information to elucidate distributions of major clades. Our results support the previously held subspecies designations based on morphological taxonomy, with 1 main exception: we determined that within A. rufa, the subspecies A. rufa rainieri and A. rufa rufa north of the Columbia River represent a single lineage and should revert to the name A. rufa olympica. Although we revised geographic boundaries for some groups (A. r. rufa, A. r. olympica, and A. r. pacifica), only the conservation status and management of A. r. olympica (previously 2 subspecies) in Canada may be affected. Our findings support the continued conservation efforts for the isolated and endangered lineages present in coastal California

Development of 10 Polymorphic Microsatellite Loci Isolated From The Mountain Beaver, \u3ci\u3eAplodontia rufa rufa\u3c/i\u3e (Rafinesque)

We developed 10 microsatellite markers for the mountain beaver, Aplodontia rufa rufa. In three populations of A. r. rufa, the number of alleles for these loci ranged from monomorphic to nine. Average observed heterozygosities in these populations ranged from 0.29 to 0.60. We also tested previously published markers from the endangered subspecies A. r. nigra in A. r. rufa populations

Mitochondrial DNA sequences

File may be viewed using ProSeq software at http://dps.plants.ox.ac.uk/sequencing/proseq.htm [Filatov DA (2009) Processing and population genetic analysis of multigenic datasets with ProSeq3 software. Bioinformatics 25: 3189-3190]

Phylogeography and Population History of Leopardus guigna, the Smallest American Felid

The guigna (Leopardus guigna) is the smallest and most-restricted New World cat species, inhabiting only around 160,000 km2 of temperate rain forests in southern South America and is currently threatened by habitat loss, fragmentation and human persecution. We investigated phylogeographic patterns of genetic diversity, demographic history and barriers to gene flow with 116 individuals sampled across the species geographic range by analyzing 1,798 base pairs of the mtDNA (496 bp HVSI region, 720 bp NADH-5 gene, 364 bp from 16S gene and 218 bp from ATP-8 gene) and 15 microsatellite loci. Mitochondrial DNA data revealed a clear phylogeographic pattern with moderate separation between northern and southern Chilean populations supporting recognized subspecific partitions based on morphology. A recent demographic expansion was inferred for the southern-most group (San Rafael Lake), presumably due to the complete coverage of this area during the last glacial period, 28000–16000 years BP. Geographical barriers such as the Andes Mountains and the Chacao Channel have partially restricted historic and more-recent gene flow and the Chiloé Island population has diverged genetically since being separated from the mainland 7000 years BP. This is the first study of the genetic structure of this threatened species throughout its whole geographic range

Data from: Phylogeography and population history of Leopardus guigna, the smallest American felid

The guigna (Leopardus guigna) is the smallest and most-restricted New World cat species, inhabiting only around 160,000 km2 of temperate rain forests in southern South America and is currently threatened by habitat loss, fragmentation and human persecution. We investigated phylogeographic patterns of genetic diversity, demographic history and barriers to gene flow with 116 individuals sampled across the species geographic range by analyzing 1,798 base pairs of the mtDNA (496 bp HVSI region, 720 bp NADH-5 gene, 364 bp from 16S gene and 218 bp from ATP-8 gene) and 15 microsatellite loci. Mitochondrial DNA data revealed a clear phylogeographic pattern with moderate separation between northern and southern Chilean populations supporting recognized subspecific partitions based on morphology. A recent demographic expansion was inferred for the southern-most group (San Rafael Lake), presumably due to the complete coverage of this area during the last glacial period, 28000–16000 years BP. Geographical barriers such as the Andes Mountains and the Chacao Channel have partially restricted historic and more-recent gene flow and the Chiloé Island population has diverged genetically since being separated from the mainland 7000 years BP. This is the first study of the genetic structure of this threatened species throughout its whole geographic range

Data from: Molecular phylogeny of an ancient rodent family (Aplodontiidae)

The family Aplodontiidae contains a single, monotypic extant genus, Aplodontia (mountain beaver), which was 1st described by Rafinesque in 1817. Phylogenetic studies have shown that it is the sister lineage to squirrels. Aplodontia rufa is endemic to the Pacific Northwest and ranges from central California to British Columbia. Currently, 7 described subspecies are recognized based on morphological taxonomic studies. In this study, mitochondrial and nuclear genes were sequenced to infer molecular phylogenies of A. rufa. One of the goals of this study was to test the current taxonomic hypothesis based on morphology with molecular data. Another goal was to incorporate geographic information to elucidate distributions of major clades. Our results support the previously held subspecies designations based on morphological taxonomy, with 1 main exception: we determined that within A. rufa, the subspecies A. rufa rainieri and A. rufa rufa north of the Columbia River represent a single lineage and should revert to the name A. rufa olympica. Although we revised geographic boundaries for some groups (A. r. rufa, A. r. olympica, A. r. pacifica), only the conservation status and management of A. r. olympica (previously 2 subspecies) in Canada may be affected. Our findings support the continued conservation efforts for the isolated and endangered lineages present in coastal California