Landscape genetic analysis of the tropical freshwater fish Mogurnda mogurnda (Eleotridae) in a monsoonal river basin: importance of hydrographic factors and population history

1. We performed spatial genetic analyses, incorporating landscape genetic methods using microsatellite data and phylogeographic analyses using mtDNA data, to identify the principal factors that determine population heterogeneity of the tropical freshwater fish, Mogurnda mogurnda, in the Daly River, northern Australia. We tested the individual and interactive effects of several environmental variables on spatial genetic patterns, including metrics relating to connectivity (i.e. stream distance, maximum stream gradient and elevation), habitat size (i.e. mean annual discharge) and a categorical variable relating to population history, as determined by mtDNA phylogeographic analyses. The Daly River is geomorphologically and hydrologically complex, and M. mogurnda has life history traits that limit its dispersal potential at river basin scales. Thus, we predicted that variables relating to connectivity would be the most important landscape factors driving population structure of the species. 2. Tree‐based phylogeographic analyses indicated four divergent mtDNA lineages within M. mogurnda in the Daly River, although three of the lineages were sympatric in various combinations and did not correspond with microsatellite groups identified by assignment tests. The allopatric mtDNA lineage detected in the uppermost part of the catchment was also identified as being highly differentiated by the microsatellite data, strongly suggesting that it may be a cryptic species. This site was therefore excluded from subsequent landscape genetic analyses. 3. Analyses of Molecular Variance indicated that M. mogurnda has a hierarchical population structure in the Daly River, thus supporting theoretical expectations that hierarchically arranged river habitats in dendritic systems impose hierarchal population structures on lotic species. 4. All landscape genetic analyses rejected stream distance, and supported stream gradient, as the major determinant of spatial genetic variation in M. mogurnda in the Daly River. Support for elevation as a determinant of spatial genetic patterns differed among the landscape genetic methods. Several of the landscape genetic methods also indicate that population history, including secondary contact between divergent and formerly allopatric genetic lineages, has a strong influence on spatial genetic patterns within M. mogurnda in the Daly River. 5. This study demonstrates the need to consider multiple environmental factors, especially factors relating to connectivity, and their interactions in spatial genetic analysis, rather than just geographic distance. Importantly, it demonstrates the need to account for population history and evolutionary divergences in landscape genetic analyses.     

Are there correlates of male Australian Magpie Gymnorhina tibicen reproductive success in a population with high rates of extra‐group paternity?

The reproductive success of a male bird is often correlated with measurable traits that predict his intrinsic quality. Females are thought to base their selection of mates on the latter's 'quality' in order to gain their 'good genes'. Male Australian Magpies Gymnorhina tibicen of the white-backed race tyrannica were trapped in two breeding seasons. Measurements were taken of morphometric and other characteristics in order to discover whether particular traits of males were associated with: (1) percentage of offspring sired in the territory, (2) number of fledglings produced in the territory per season and (3) whether females select males for their 'good genes'. There were no consistently significant correlations between any of the measured variables and male Magpie reproductive success within territories. In particular, none of the traits measured had any consistent correlation with the percentage of offspring sired in a territorial group. This was an unexpected result given that the species is strongly territorial but also engages regularly in extra-group copulations. These findings appear contrary to the predictions of the 'good genes' hypothesis. The general lack of correlation between the variables and level of genetic paternity may in fact be due to females engaging in extra-group mating primarily to avoid breeding with a close relative rather than to choose a high-quality male. In this case, males would not have to be 'high quality', but merely genetically different from the female's social mate.     

Quantifying the activity levels and behavioural responses of butterfly species to habitat boundaries

1. The ability of species' to undergo climate‐driven range shifts across fragmented landscapes depends on their dispersal ability as well as the structure of the landscape. For species' range shifts to occur, individuals must first leave suitable habitat to seek new habitat; this is likely to depend on the rate of movement of individuals within habitat and the likelihood that a boundary is crossed, once it is encountered. For three species of butterfly with contrasting histories of recent range expansion, we examined the propensity of individuals to move within a habitat and their responses to habitat boundaries. 2. We quantified the extent to which Plebejus argus (Linnaeus) (a declining habitat specialist), Aricia agestis (Schiffermuller) (an expanding generalist) and Polymmatus icarus (Rottemburg) (a geographically ubiquitous generalist) crossed habitat boundaries into unsuitable habitat and moved within suitable habitat. The observed movement was then related to individual and environmental conditions. 3. Species differed in their activity levels in accordance within their recent distribution patterns (P. icarus > A. agestis > P. argus). Our results for P. argus suggest that movement may be motivated by nectar‐seeking, and that males generally move more than females. All three species tended to avoid crossing habitat boundaries; however the proportion of individuals crossing habitat boundaries did not differ significantly among species. 4. We conclude that levels of activity within a habitat, which will affect the frequency with which individuals encounter habitat boundaries, rather than behavioural responses to the boundaries, may be important drivers of distribution change.     

Sandfly distribution and abundance in a tropical rain forest

1. The distribution patterns of sandflies (Diptera: Psychodidae) upon tree buttresses were studied in tropical rain forest at Finca la Selva in the Caribbean lowlands of Costa Rica. 2. Four species of sandfly, Lutzomyia shannoni Dyar, L. trapidoi F. & H., L. ylephiletor F. & H. and L. vespertilionis F. & H. comprising 97% of those caught, used tree buttresses as diurnal resting sites. Their distribution on the buttresses was aggregated. 3. During the dry season tree species had no significant effect upon the distribution of the sandflies. However, during the wet season the distributions of two of the species, L. trapidoi and L. ylephiletor, were significantly affected by the species of tree; it is suggested that some species of tree may provide greater protection from rainfall than others. 4. L. vespertilionis was restricted to a single buttress on each positive tree. Distribution of this species is evidently determined by the distribution of its host animal, the bat (Emballonuridae). Female flies feed upon the bat's blood and male flies may be attracted to the bat as it provides a source of female sandflies. It is suggested, therefore, that tree buttresses serve as sandfly swarming sites. 5. Within a large buttress the sandflies are not randomly distributed but are aggregated in particular areas. Within these aggregations, the sandflies are vertically zoned upon the buttress with a shift in species composition with height. Two hypothesis were suggested to account for this distribution pattern: a response to an environmental gradient or an interaction between the four species of fly.     

Light induction of alternative pathway capacity in leaf slices of Belgium endive

The effect of light on the development of the capacity for alternative pathway respiration was investigated in leaf slices of Belgium endive (Cichorum intybus L. cv. deliva). Dark-grown plants possessed little capacity for the cyanide-insensitive alternative pathway. In contrast, plants grown in continuous light had significant alternative pathway capacity. Light-grown plants also had substantially higher concentrations of ethanol-soluble carbohydrates in their leaves than plants grown in complete darkness. Despite these differences in leaf carbohydrate status and alternative pathway capacity of light- and dark-grown leaf tissue, no differences were found in the activity of the alternative pathway, which was negligible in both treatments. Dark-grown plants were adenylate restricted, as indicated by the increase in cytochrome pathway activity following uncoupling. Adenylates did not limit respiration in light-grown leaf tissue. Plants that had been grown for 8d in complete darkness were also transferred to continuous light. Respiration of dark controls steadily declined over 11d following the transfer of plants to the light, due primarily to a decrease in cytochrome pathway activity. No such decline was observed in the plants transferred to continuous light. Transfer to continuous light led to significant increases in alternative pathway capacity relative to the dark controls. Alternative pathway activity remained negligible in both the dark controls and in plants transferred to continuous light. The results of this study suggest then that light per se may be responsible for the induction of alternative pathway capacity in Belgium endive.     

Isolation and characterization of polymorphic microsatellite loci in the Australian smelt,Retropinna semoni

Five polymorphic microsatellite loci were isolated from the Australian smelt, Retropinna semoni, in order to study levels of connectivity among populations at various spatial scales. Screening of one natural population (n = 30) from central Victoria, southeastern Australia, yielded nine to 14 alleles per locus with observed levels of heterozygosity ranging from 0.40 to 0.80. All loci were in Hardy–Weinberg equilibrium after Bonferroni correction for multiple tests. These loci should provide a useful tool in further understanding the population genetics of this species.     

A comparison of the floristics and leaf chemistry of the tree flora in two Malaysian rain forests and the influence of leaf chemistry on populations of colobine monkeys in the Old World

A comparative floristic survey of lowland tropical rain forest at Kuala Lompat, Krau Game Reserve, West Malaysia and at Sepilok Virgin Jungle Reserve, Sabah, East Malaysia, revealed significant differences in the composition of canopy species, notably in the relative paucity of Dipterocarpaceae and abundance of Leguminosae at Kuala Lompat. A further comparison with data from other sites in Malesia indicated that Kuala Lompat was rather atypical, representing an extreme example of the relatively legume rich and dipterocarp poor forests of West Malaysia. Conversely, the predominance of dipterocarps and lack of legumes at Sepilok was similar to other sites in Borneo. Young and mature leaves were collected from a representative sample of the canopy flora of the two study sites; the levels of nitrogen, fibre, total phenolics and condensed tannins, and degree of digestibility by cellulase and pepsin, were measured. Levels of fibre, nitrogen and phenolics differed significantly between the two floras; foliage from Kuala Lompat being, on the whole, richer in nitrogen but lower in phenolics and fibre. As a consequence of the lower levels of fibre, and less certainly of phenolics, the Kuala Lompat foliage was comparatively more digestible. Possible reasons for the differences in foliar biochemistry between the two sites are discussed. Differences in rainfall and in soil quality are regarded as potential evolutionary causes. A further comparison of the chemical profiles with data for other forests in India and Africa indicate that Sepilok is a site in which trees invest heavily in quantitative defences such as fibre and phenolics whereas trees at Kuala Lompat place a lower emphasis on the production of these. Finally, attention is drawn to the use of foliar chemical profiles in predicting the carrying capacity for colobine monkeys at each of the five Old World forests where data are available. It was found that the ratio of nitrogen to fibre correlated well with the biomass of colobines at the five sites.     

Variation in Brood Sex Ratios of Texas Rio Grande Wild Turkeys

Abstract: We evaluated brood sex ratio (BSR) variation in Rio Grande wild turkeys (RGWT; Meleagris gallopavo intermedia) in the Edwards Plateau and South Texas Plains of Texas, USA, during 2005-2006. Offspring sex was determined from DNA extracted from tissue biopsies of embryos from unhatched eggs or vascular tissue from eggshells of hatched and depredated eggs. Sex ratio across all eggs was 56.3% male (135/240; X²₁ = 3.75, P = 0.053). We found that mean population growth rate based on a population simulation with BSR at unity averaged 1.02 (range = 0.924-1.058), whereas it declined to 0.978 (range = 0.816-1.037) using BSR estimates from our study. Although our statistical analyses did not detect BSRs different from unity in BSR, our simulation modeling demonstrated that BSR variation caused biologically significant differences in mean population growth rates. Even though the biological mechanism controlling primary sex ratio remains unknown, our estimates of BSR should allow managers to more reliably predict population dynamics insuring viable RGWT populations across Texas.