Microsatellite DNA markers for the study of population structure and dynamics in nutria (Myocastor coypus)

We document the isolation and characterization of 27 microsatellite DNA markers for nutria, or coypu (Myocastor coypus), an invasive rodent introduced to North America as a domestic furbearer. Markers revealed moderate levels of diversity (averaging 5.0 alleles/locus) and heterozygosity (averaging 46%). Genotypic frequencies at 25 of 27 (93%) markers conformed to Hardy–Weinberg equilibrium expectations and no linkage disequilibrium was observed in a M. coypus collection (N = 64) from Maryland, USA. We believe this suite of markers to yield sufficient diversity to resolve patterns of effective migration among subpopulations, breeding structure, and demographics. This information can be instrumental to eradication programs that attempt to prevent recolonization among subpopulations.     

Volatile chemical release by bethylid wasps: identity, phylogeny, anatomy and behaviour

The structures of volatile chemicals released by parasitic wasps in the family Bethylidae are shown to correspond to the subfamily to which the species belong. Species in the Epyrinae release skatole (3-methylindole) and species in the Bethylinae release a spiroacetal (2-methyl-1,7-dioxaspiro [5.5]undecane): these compounds are chemically very different. The enantiomeric composition of the spiroacetal differs between congeneric species. Chemical release is a discrete event under the active control of both male and female wasps. Structural differences between the mandibular glands and intramandibular glands suggest the mandibular glands to be the source of released volatiles. Real-time mass spectrometry shows that the spiroacetal is released by Goniozus nephantidis females during dyadic resource contests, with release more common during more aggressive interactions. Chemical tagging with deuterium further shows that the volatile is released by the loser of an agonistic interaction and not the winner. The function of spiroacetal and skatole release by bethylids is discussed.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 837–852.     

Dispersal of freshwater invertebrates by large terrestrial mammals: a case study with wild boar (Sus scrofa) in Mediterranean wetlands

1. Many invertebrates inhabiting insular aquatic habitats rely on external agents or vectors to disperse. Besides water connections and wind, waterfowl and amphibians are known to mediate passive dispersal of freshwater invertebrates. However, the possibility of dispersal by terrestrial mammals has been largely overlooked. 2. We investigated the potential of both external and internal zoochorous dispersal of aquatic invertebrates by the wild boar (Sus scrofa) in Mediterranean wetlands in the Camargue (France). As wild boar frequently visit wetlands for feeding and wallowing purposes, we hypothesized that they may be important passive dispersal vectors of aquatic invertebrates at a local scale. Dried mud was collected from selected ‘rubbing trees’ used by boars to dispose of parasites. Additionally, faecal pellets were collected from different locations in the wetland area. 3. Seventeen freshwater invertebrate taxa including rotifers, cladocerans, copepods and ostracods hatched from sediment obtained from ‘rubbing trees’, while invertebrates hatching from dried faeces (10 taxa) were mainly rotifers. Dispersing invertebrates were collected up to 318 m from a nearest potential dispersal source. Both abundance and richness of invertebrates significantly decreased with dispersal distance. 4. Our results demonstrate that large mammals such as wild boar can act as dispersal vectors of aquatic invertebrates at a local scale in the wetland area of the Camargue and suggest that external transport may be quantitatively more important than internal transport. As wallowing (mud bathing) is common in many terrestrial mammals, this mode of dispersal may be quite widespread.     

Parentage of endemic Sorbus L. (Rosaceae) species in the British Isles: evidence from plastid DNA

The parentage of polyploid Sorbus species in the British Isles was investigated using plastid DNA microsatellites. Four hundred and fifty-three samples from 30 taxa were screened using six microsatellite fragments, which gave 28 haplotypes. The haplotypes formed groups clearly related to the ancestral diploids Sorbus aria , Sorbus aucuparia , and Sorbus torminalis . Species in the Sorbus aria group all had Aria haplotypes (with the exception of one English S. aria ), species in the Sorbus anglica group had an Aucuparia haplotype, and species in the Sorbus latifolia group had a Torminalis haplotype. Sorbus intermedia had an Aucuparia haplotype. This indicated that the hybridization events that led to the formation of species in the S. anglica and S. latifolia groups usually did so with S. aria s.l . as the pollen-donating (paternal) parent. The polyploids S. anglica , Sorbus bristoliensis , Sorbus croceocarpa , Sorbus decipiens , Sorbus devoniensis , Sorbus hibernica , Sorbus lancastriensis , Sorbus leptophylla , Sorbus leyana , Sorbus minima , Sorbus rupicola , Sorbus subcuneata , Sorbus vexans , Sorbus whiteana , Sorbus wilmottiana , and three unnamed taxa may each be derived from a single maternal lineage. The polyploids Sorbus eminens , Sorbus porrigentiformis , and S. latifolia have multiple maternal lineages. The two primary diploid hybrids S . ×  thuringiaca and S . ×  vagensis have arisen many times independently.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 291–304.     

Gut content and stable isotope analyses provide complementary understanding of ontogenetic dietary shifts and trophic relationships among fishes in a tropical river

1. Despite widespread recognition of the role of body size in fish trophic ecology, little attention has been focused on this issue in isotopic studies, particularly in tropical systems. 2. We used analyses of stomach contents and stable isotopes to examine size‐related shifts in diet in a terapontid fish assemblage in the Australian wet–dry tropics. Stomach content analysis identified substantial ontogenetic dietary shifts in all species, corresponding to changes in body size–isotope trajectories for two species. Shifts away from relatively specialised diets of heavily ¹³C‐depleted insect larvae to consumption of a range of items across multiple basal carbon sources appeared to be the proximate cause of observed isotopic changes. 3. Allochthonous organic matter in the form of C3 riparian vegetation was particularly important to smaller terapontids before larger fish shifted to a broad range of dietary items and similarly broad range of basal carbon sources. 4. While there was general agreement between δ¹³C and stomach content analysis, there was minimal concurrence between the latter and δ¹⁵N isotopic derivation of estimates of trophic position. Due to factors such as omnivory, isotopically overlapping basal sources and uncertainties about rates of isotopic fractionation in both predator and prey species, stomach content analysis provides an essential complement to isotopic methodologies in tropical systems. 5. Given that basal sources supporting any individual species can change markedly with ontogeny, consideration of intraspecific, size‐related variation is necessary in isotopic studies of food web structure.     

Isolation and cross‐familial amplification of 41 microsatellites for the brook charr (Salvelinus fontinalis)

The brook charr (Salvelinus fontinalis; Osteichthyes: Salmonidae) is a phenotypically diverse fish species inhabiting much of North America. But relatively few genetic diagnostic resources are available for this fish species. We isolated 41 microsatellites from S. fontinalis polymorphic in one or more species of salmonid fish. Thirty‐seven were polymorphic in brook charr, 15 in the congener Arctic charr (Salvelinus alpinus) and 14 in the lake charr (Salvelinus namaycush). Polymorphism was also relatively high in Oncorhynchus, where 21 loci were polymorphic in rainbow trout (Oncorhynchus mykiss) and 16 in cutthroat trout (Oncorhynchus clarkii) but only seven and four microsatellite loci were polymorphic in the more distantly related lake whitefish (Coregonus clupeaformis) and Atlantic salmon (Salmo salar), respectively. One duplicated locus (Sfo228Lav) was polymorphic at both duplicates in S. fontinalis.     

Trends and temperature response in the phenology of crops in Germany

The phenology of 78 agricultural and horticultural events from a national survey in Germany spanning the years 1951–2004 is examined. The majority of events are significantly earlier now than 53 years ago, with a mean advance of 1.1–1.3 days per decade. The mean trends for 'true phases', such as emergence and flowering, of annual and perennial crops are not significantly different, although more trends (78% vs. 46%) are significant for annual crops. We attempt to remove the influence of technological advance or altered farming practices on phenology by detrending the respective time series by linear regression of date (day number) on year. Subsequently, we estimate responses to mean monthly and seasonal temperature by correlation and regression in two ways; with and without removing the year trend first. Nearly all (97%) correlation coefficients are negative, suggesting earlier events in warmer years. Between 82% and 94% of the coefficients with seasonal spring and summer temperatures are significant. The conservative estimate (detrended) of mean temperature response against mean March–May temperature (−3.73 days °C⁻¹) is significantly less than the full estimate (−4.31 days °C⁻¹), the 'true' size of phenological temperature response may lie in between. Perennial crops exhibited a significantly higher temperature response to mean spring temperature than the annual crops.