Metal content in insects associated with ultramafic and non-ultramafic sites in the Scottish Highlands

1. Concentrations of magnesium, manganese, chromium, and cadmium were measured in Coleoptera, Diptera, Hemiptera, and Hymenoptera captured at ultramafic and non-ultramafic sites in the Highlands of Scotland. 2. The Hemiptera showed the greatest concentration differences between the ultramafic and non-ultramafic sites in manganese, magnesium, and chromium, with greatly increased levels in ultramafic sites. 3. The Coleoptera and Hymenoptera had lower levels of manganese, magnesium, and chromium at the ultramafic site than at the non-ultramafic sites. The Diptera had increased levels of manganese and magnesium at the ultramafic site, but showed no difference in chromium levels from any site. 4. Cadmium occurred at lower levels in all insect orders at the ultramafic site.     

Cryptic species,gene recombination and hybridization in the genus Spiraeanthemum (Cunoniaceae) from New Caledonia

The Oceanian plant genus Spiraeanthemum (Cunoniaceae) has a centre of diversity in New Caledonia, where it is represented by seven species. Its diversification was investigated using two low‐copy nuclear genes, ncpGS and GapC, and phylogenetic analyses were based on maximum parsimony, maximum likelihood and recombination networks. We detected several cases of gene recombination in both datasets, and these have obscured the history within the genus. For S. ellipticum and S. pubescens, accessions from southern populations on ultramafic soils were genetically distinct from accessions from northern populations on non‐ultramafic soils. Given that no obvious morphological characters distinguish northern and southern populations in either taxon, both may be considered as examples of cryptic species. Incongruence between gene trees and species' delimitation may be explained by the parallel evolution of similar morphology, differential lineage sorting leading to differential fixation of alleles or different introgression patterns in the north and south leading to allele displacement. In New Caledonia, some species with broad ecological preferences may thus be artificial concepts. This suggests that they should be treated more critically in monographs and that the species' richness of the New Caledonian flora may be underestimated. Problems associated with the typification of S. ellipticum and evidence of hybridization events in the history of Spiraeanthemum are also discussed. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161 , 137–152.     

The Genetic Basis of Metal Hyperaccumulation in Plants

Referee: Professor Alan J.M. Baker, School of Botany, The University of Melbourne, VIC 3010, Australia A relatively small yet diverse group of plants are capable of sequestering metals in their shoot tissues at remarkably high concentrations that would be toxic to most organisms. This process, known as metal hyperaccumulation, is of interest for several reasons, including its relevance to the phytoremediation of metalpolluted soils. Most research on hyperaccumulators has focused on the physiological mechanisms of metal uptake, transport, and sequestration, but relatively little is known regarding the genetic basis of hyperaccumulation. There are no known cases of major genetic polymorphisms in which some members of a species are capable of hyperaccumulation and others are not. This is in contrast to the related phenomenon of metal tolerance, in which most species that possess any metal tolerance are polymorphic, evolving tolerance only in local populations on metalliferous soil. However, although some degree of hyperaccumulation occurs in all members of the species that can hyperaccumulate, there is evidence of quantitative genetic variation in ability to hyperaccumulate, both between and within populations. Such variation does not appear to correlate positively with either the metal concentration in the soil or the degree of metal tolerance in the plant. Studies using controlled crosses, interspecific hybrids, and molecular markers are beginning to shed light on the genetic control of this variation. As molecular physiology provides greater insights into the specific genes that control metal accumulation, we may learn more about the genetic and regulatory factors that influence variable expression of the hyperaccumulation phenotype.     

Morphological and genetic analysis of the Red Hills roach (Cyprinidae: Lavinia symmetricus)

We performed a morphological and phylogeneticanalysis of a recently discovered population ofCalifornia roach (Red Hills roach; Cyprinidae:Lavinia symmetricus) to determine if thedegree of separation of these populationswarrants subspecies status. Previousmorphological analysis by Brown et al. (1992)suggested that L. symmetricus from theRed Hills roach type locality (Horton Creek)were different for Principal DiscriminantScores (based on 15 morphological characters)from neighboring populations. Similarly,recent work by our lab on the phylogenetics ofthe putative subspecies of L. symmetricushas revealed that the Red Hills roach appearsreciprocally monophyletic for assayedmitochondrial DNA markers. In addition toperforming further morphological and geneticanalysis of the Red Hills roach, we increasedour sampling effort in the Red Hills region todetermine the distribution of this undescribedputative subspecies. Our morphological resultsare generally in agreement with Brown et al.(1992) except in regards to Horton Creek. Asignificant difference between the two studiesexists for all Horton Creek multivariateanalyses as well as frequency of a presumablyderived character (chisel lip). Our geneticresults also support our previous findings thatthe Red Hills roach is a diagnosible,genetically distinct population. Thephylogenetic analysis suggests that populationson the other side of a large reservoir wererecently connected via gene flow to the RedHills populations.