Comparative phylogeography of three rainforest-restricted lizards from mid-east Queensland

Several small isolates of rainforest situated on the central eastern coast of Australia are home to a rich herpetofauna, including four endemic species of leaftail geckos (Phyllurus spp.) and two skinks (Eulamprus spp.). To examine the extent and geographic pattern of historical subdivision among isolates, we assayed mtDNA variation in two species endemic to rainforests of this region (Phyllurus ossa and Eulamprus amplus) and, for comparison, a more widespread and less specialised lizard, Carlia rhomboidalis. There is a clear genetic signature of historical changes in population size and distribution in P. ossa that is consistent with Pleistocene (or earlier) rainforest contraction and subsequent expansion. Although more pronounced in the gecko, phylogeographic structure was congruent between E. amplus and P. ossa. In contrast to the saxicolous, rainforest-restricted P. ossa and E. amplus, the rainforest-generalist species, C. rhomboidalis, does not display strong geographic population structure. The differences in genetic population structure exhibited by the three species are consistent with species-specific differences in ecology.

Comparative phylogeography of two open forest frogs from eastern Australia

We investigated the phylogeography of two closely related Australian frog species from open forest habitats, Limnodynastes tasmaniensis and L. peronii, using mitochondrial ND4 sequence data. Comparison of our results with previous work on Litoria fallax allowed us to test the generality of phylogeographic patterns among non-rainforest anurans along the east coast of Australia. In general, there was no strong evidence for congruence between overall patterns of genetic structure in the three species. However, phylogenetic breaks congruent with the position of the Burdekin Gap were detected at some level in all species. As previously noted for closed forest taxa, this area of dry habitat appears to have been an important influence on the evolution of several open forest taxa. There were broad geographic similarities in the phylogenetic structuring of southern populations of L. peronii and L. tasmaniensis. Contrarily, although the McPherson Range has previously been noted to coincide geographically with a major mtDNA phylogenetic break in Litoria fallax this pattern is not apparent in L. peronii or L. tasmaniensis. It appears that major phylogeographic splits within L. peronii and L. tasmaniensis may predate the Quaternary. We conclude that phylogeographies of open forest frogs are complex and more difficult to predict than for rainforest taxa, mainly due to an absence of palaeomodels for historical distributions of non-rainforest habitats. (C) 2001 The Linnean Society of London.

Resolution of natural groups using iterative assignment tests: an example from two species of Australian native rats (Rattus)

Sympatric individuals of Rattus fuscipes and Rattus leucopus, two Australian native rats from the tropical wet forests of north Queensland, are difficult to distinguish morphologically and are often confused in the field. When we started a study on fine-scale movements of these species, using microsatellite markers, we found that the species as identified in the field did not form coherent genetic groups. In this study, we examined the potential of an iterative process of genetic assignment to separate specimens from distinct (e.g. species, populations) natural groups. Five loci with extensive overlap in allele distributions between species were used for the iterative process. Samples were randomly distributed into two starting groups of equal size and then subjected to the test. At each iteration, misassigned samples switched groups, and the output groups from a given round of assignment formed the input groups for the next round. All samples were assigned correctly on the 10th iteration, in which two genetic groups were clearly separated. Mitochondrial DNA sequences were obtained from samples from each genetic group identified by assignment, together with those of museum voucher specimens, to assess which species corresponded to which genetic group. The iterative procedure was also used to resolve groups within species, adequately separating the genetically identified R. leucopus from our two sampling sites. These results show that the iterative assignment process can correctly differentiate samples into their appropriate natural groups when diagnostic genetic markers are not available, which allowed us to resolve accurately the two R. leucopus and R. fuscipes species. Our approach provides an analytical tool that may be applicable to a broad variety of situations where genetic groups need to be resolved.

Breeding dynamics of koalas in open woodlands

The spatial and breeding dynamics of koalas in sub-tropical woodlands at Blair Athol in central Queensland were intensively monitored between 1993 and 1998. Genetic relationships among koalas at this locality were studied to determine the breeding dynamics of males, including whether 'resident' or 'transient' males dominate as sires. Males and females were radio-collared and tracked periodically throughout each year of the study. Genotypes from hypervariable microsatellite loci identified uniquely all individuals and were used to analyse parentage as well as to determine population genetic parameters when compared with other regional localities. Koalas at Blair Athol comprise a population in genetic equilibrium. Gene diversity estimates show the population to be similar to other populations found in similar habitat in the region, and estimates of genetic differentiation among four regional populations showed that gene flow conforms to a model of isolation by distance. Analysis of parentage found that both resident and transient males sired about equal numbers of offspring. Familial DNA analysis revealed multiple paternities of successive young in this population. The conclusion from this study is that 'resident' status among males does not confer any advantage for parentage.

Transpecific microsatellites for hard pines M. Shepherd, M. Cross, T. Maguire, M. Dieters, C. Williams, R. Henry

Microsatellites are difficult to recover from large plant genomes so cross-specific utilisation is an important source of markers. Fifty micro satellites were tested for cross-specific amplification and polymorphism to two New World hard pine species, slash pine (Pinus elliottii var. elliottii) and Caribbean pine (R caribaea var. hondurensis). Twenty-nine (58%) markers amplified in both hard pine species, and 23 of these 29 were polymorphic. Soft pine (subgenus Strobus) microsatellite markers did amplify, but none were polymorphic. Pinus elliottii var. elliottii and R caribaea var. hondurensis showed mutational changes in the flanking regions and the repeat motif that were informative for Pinus spp. phylogenetic relationships. Most allele length variation could be attributed to variability in repeat unit number. There was no evidence for ascertainment bias.

Low intraspecific variation in the rRNA internal transcribed spacer 2 (ITS2) of the Australian paralysis tick, Ixodes holocyclus

Ixodes holocyclus has a narrow, discontinuous distribution along the east coast of Australia. We studied ticks from 17 localities throughout the geographic range of this tick. The ITS2 of I. holocyclus is 793 bp long. We found nucleotide variation at eight of the 588 nucleotide positions (1.4%) that were compared for all ticks. There were eight different nucleotide sequences. Most sequences were not restricted to a particular geographic region. However, sequences F, G and H, which had an adenine at position 197, were found only in the far north of Queensland - all other ticks had a guanine at this position. The low level of intraspecific variation in this tick (0.7%) contrasts with the sequence divergence between L holocyclus and its close relative, I. cornuatus (13.1 %). These data indicate that L holocyclus does not contain cryptic species despite possible geographic isolation of some populations. We conclude that variation in the ITS2 is likely to be informative about the phylogeny of the group.

Phylogeography of the pipefish, Urocampus carinirostris, suggests secondary intergradation of ancient lineages

We assayed the pattern of mitoehondrial DNA evolution in the live bearing, seagrass specialist pipefish, Urocampus carinirostris, in eastern Australia. These life history attributes were predicted to result in strong phylogeographic structure in U. carinirostris. Phylogenetic analysis of cytochrome b sequences detected two monophyletic mtDNA clades that differed by 8.69% sequence divergence - a large level of intraspecific divergence for a marine fish. The geographical distribution of clades was non-random and resembled clinal secondary intergradation over a 130-km stretch of coastline. Contrary to phylogeographic predictions, this large phylogeographic break does not occur across a traditionally recognised biogeographic boundary. Analyses of historical demography suggested that individuals belonging to the most widespread clade underwent a population expansion from a small refuge population during the Pleistocene.

Social structure in migrating humpback whales (Megaptera novaeangliae)

Although largely solitary, humpback whales exhibit a number of behaviours where individuals co-operate with one another, for example during bubble net feeding. Such cases could be due to reciprocal altruism brought on by exceptional circumstances, for example the presence of abundant shoaling fish. An alternative explanation is that these behaviours have evolved through kin selection. With little restriction to either communication or movement, diffuse groups of relatives could maintain some form of social organization without the need to travel in tight-nit units. To try to distinguish between these hypotheses, we took advantage of the fact that migrating humpback whales often swim together in small groups. If kin selection is important in humpback whale biology, these groups should be enriched for relatives. Consequently, we analysed biopsy samples from 57 groups of humpback whales migrating off Eastern Australia in 1992. A total of 142 whales were screened for eight microsatellite markers. Mitochondrial DNA sequences (371 bp) were also used to verify and assist kinship identification. Our data add support to the notion that mothers travel with their offspring for the first year of the calf's life. However, beyond the presence of mother-calf/yearling pairs, no obvious relatedness pattern was found among whales sampled either in the same pod or on the same day. Levels of relatedness did not vary between migratory phases (towards or away from the breeding ground), nor between the two sexes considered either overall or in the north or south migrations separately. These findings suggest that, if any social organization does exist, it is formed transiently when needed rather than being a constant feature of the population, and hence is more likely based on reciprocal altruism than kin selection.

Susceptibility of head lice (Pediculus humanus capitis) to pediculicides in Australia

Infestation with head lice, Pediculus humanus capitis, is a worldwide problem, especially among primary (elementary) school children. Although studies in many different countries indicate lower levels of susceptibility to certain insecticides than expected ('resistance'), there is no empirical data from Australia. Data on the susceptibility of head lice to malathion, pyrethrums and permethrin were collected from four schools in Brisbane and one school in northern Queensland. Since no completely susceptible strain of head lice was available and head lice are difficult to keep in culture, a completely susceptible strain of body lice, Pediculus humanus humanus, was used for reference. All five groups of head lice were less susceptible to malathion, pyrethrums and permethrin than were lice from the reference strain. Moreover, the degree of susceptibility to these insecticides varied substantially among schools. Thus, a pediculicide that controlled lice at one school in Brisbane would not necessarily control head lice at another school in the same city. These preliminary data indicate that detailed information on the susceptibility of the different populations of head lice in Queensland to the different insecticides available is needed to maximize the chance of effective control of these increasingly common parasites.

Lack of intraspecific biological variation between two geographical populations of Oomyzus sokolowskii (Hymenoptera: Eulophidae), a gregarious larval–pupal parasitioid of Plutella xylostella (Lepidoptera: Plutellidae)

The chalcid, Oomyzus sokolowskii Kurdjumov has been recorded in many parts of the world as a major larval-pupal, gregarious endoparasitoid of the diamondback moth, Plutella xylostella (Linnaeus), a serious pest of brassica vegetable crops worldwide. This study investigated intraspecific variation between two populations of O. sokiolowskii, one from Cape Verde Islands, West Africa and the other from Hangzhou, China. In all crosses and backcrosses between the two geographical populations, the numbers of progeny and sex ratio of progeny were similar to those obtained within each of the populations, demonstrating complete reproductive compatibility between the two populations. The two populations showed similar responses to temperature with respect to development time and survival of immature stages. Observations on the interactions between the two O. sokolowskii populations and Cotesia plutellae (Kurdjumov), another major parasitoid of P. xylostella, showed that neither population could achieve successful parasitism of P. xylostella larvae already parasitized by C. plutellac. However, both O. sokolowskii populations could achieve hyperparasitism by ovipositing into a mid-late stage larva of C. plutellae developing inside the primary host. Contrary to earlier reports, no evidence of intraspecific variations in ability to hyperparasitize between these two populations of O. sokolowskii was found.

Targeting genetic resource conservation in widespread species: a case study of Cedrela odorata L.

Conservation of genetic resources is a recognised necessity for the long term maintenance of evolutionary potential. Effective assessment and implementation Strategies are required to permit rapid evaluation and protection of resources. Here we use information from the chloroplast, total genome and quantitative characters assayed across wide-ranging populations to assess genetic resources in a Neotropical tree, Cedrela odorata. A major differentiation identified for organelle, total genomic and quantitative variation was found to coincide with an environmental gradient across Costa Rica. However, a major evolutionary divergence between the Yucatan region and Honduras/Nicaragua identified within the chloroplast genome was not differentiated using quantitative characters. Based on these and other results, a three-tiered conservation genetic prioritisation process is recommended. In order of importance, and where information is available, conservation units should be defined using quantitative (expressed genes), nuclear (genetic connectivity) and organellar (evolutionary) measures. Where possible, information from range wide and local scale studies should be combined and emphasis should be placed on coincidental disjunctions for two or more measures. However, if only rapid assessments of diversity are possible, then assessment of organelle variation provides the most cautious assessment of genetic resources, at least for C. odorata, and can be used to propose initial conservation units. When considering effective implementation of genetic resource management strategies a final tier should be considered, that of landuse/geopolitical divisions. (C) 2004 Elsevier B.V. All rights reserved.