Population genetic structure, gene flow and sex-biased dispersal in frillneck lizards (Chlamydosaurus kingii)

By using both mitochondrial and nuclear multiloci markers, we explored population genetic structure, gene flow and sex-specific dispersal of frillneck lizards ( Chlamydosaurus kingii ) sampled at three locations, separated by 10 to 50 km, in a homogenous savannah woodland in tropical Australia. Apart from a recombinant lizard, the mitochondrial analyses revealed two nonoverlapping haplotypes/populations, while the nuclear markers showed that the frillneck lizards represented three separate clusters/populations. Due to the small population size of the mtDNA, fixation may occur via founder effects and/or drift. We therefore suggest that either of these two processes, or a combination of the two, are the most likely causes of the discordant results obtained from the mitochondrial and the nuclear markers. In contrast to the nonoverlapping mitochondrial haplotypes, in 12 out of 74 lizards, mixed nuclear genotypes were observed, hence revealing a limited nuclear gene flow. Although gene flow should ultimately result in a blending of the populations, we propose that the distinct nuclear population structure is maintained by frequent fires resulting in local bottlenecks, and concomitant spatial separation of the frillneck lizard populations. Limited mark–recapture data and the difference in distribution of the mitochondrial and nuclear markers suggest that the mixed nuclear genotypes were caused by juvenile male-biased dispersal.     

AMPHIBIANS FROM THE MIDDLE JURASSIC BALABANSAI SVITA IN THE FERGANA DEPRESSION, KYRGYZSTAN (CENTRAL ASIA)

Abstract: Larval and metamorphosed Ferganobatrachus riabinini (Temnospondyli, Brachyopoidea), metamorphosed Kokartus honorarius (Caudata, Karauridae), an indeterminated karaurid (Karauridae indet.) and, presumably, anurans (?Anura indet.) are represented by isolated cranial and postcranial skeletal elements in the Middle Jurassic (Bathonian–Callovian) Balabansai Svita of the Fergana Depression, Kyrgyzstan. The Balabansai vertebrate assemblage is one of the few faunas in which non‐lissamphibian temnospondyls, stem caudates and anurans occur together. The presence of a supraglenoid foramen and a complex strap‐like glenoid on the scapulocoracoid in Kokartus supports its basal phylogenetic position within the Caudata.     

Survival of Dusky Canada Goose Goslings in Relation to Weather and Annual Nest Success

Abstract The dusky Canada goose (Branta canadensis occidentalis) population has been in long-term decline, likely due to reduced breeding productivity, but gosling survival of this population had not been examined. We studied gosling survival in broods of radiomarked adult females on the western Copper River Delta, Alaska, USA, during 1997–1999 and 2001–2003. Survival estimates for dusky Canada goose goslings to 45 days (x̄ = 0.32) were below estimates from most previous studies of geese. Daily survival of goslings increased with age and decreased with date of hatch. Precipitation during the first 3 days post-hatch was negatively related to gosling survival and this effect increased with date. Annual estimates of gosling survival were positively correlated with annual estimates of nest success, suggesting overlap in factors affecting nest and gosling survival. Nest success probably also directly affected gosling survival, because survival decreased with hatch date and more broods hatched from renests during years with low nest success. Gosling survival appears to play an important role in limiting current productivity of this population. Management directed at increasing nest success would likely also improve gosling survival. We recommend additional research directed at examining sources of gosling mortality and the link between nest success and gosling survival.     

Indirect Effects of a Keystone Herbivore Elevate Local Animal Diversity

Abstract: We quantified indirect effects of white-tailed deer (Odocoileus virginianus) on ground-dwelling herpetofauna and invertebrates in Cuyahoga Valley National Park, Ohio, USA. We placed cover boards at 12 sites, each consisting of a 10 × 10-m fenced (exclosure) plot and an unfenced (control) plot. Periodically, during May-December 2004 and May-September 2005, we counted salamanders, snakes, and a variety of invertebrate taxa. Salamander, snake, and gastropod abundance as well as invertebrate richness (no. of species or higher level taxa) were higher in control than exclosure plots. Our findings suggest that management actions taken to regulate deer densities could have the unintended effect of reducing local animal diversity.     

The Ordovician Biodiversification: revolution in the oceanic trophic chain

The Early Palaeozoic phytoplankton (acritarch) radiation paralleled a long-term increase in sea level between the Early Cambrian and the Late Ordovician. In the Late Cambrian, after the SPICE δ¹³C_carb excursion, acritarchs underwent a major change in morphological disparity and their taxonomical diversity increased to reach highest values during the Middle Ordovician (Darriwilian). This highest phytoplankton diversity of the Palaeozoic was possibly the result of palaeogeography (greatest continental dispersal) and major orogenic and volcanic activity, which provided maximum ecospace and large amounts of nutrients. With its warm climate and high atmospheric CO₂ levels, the Ordovician was similar to the Cretaceous: a period when phytoplankton diversity was at its maximum during the Mesozoic. With increased phytoplankton availability in the Late Cambrian and Ordovician a radiation of zooplanktonic organisms took place at the same time as a major diversification of suspension feeders. In addition, planktotrophy originated in invertebrate larvae during the Late Cambrian–Early Ordovician. These important changes in the trophic chain can be considered as a major palaeoecological revolution (part of the rise of the Palaeozoic Evolutionary Fauna of Sepkoski). There is now sufficient evidence that this trophic chain revolution was related to the diversification of the phytoplankton, of which the organic-walled fraction is partly preserved.     

The phylogeographical and management implications of genetic population structure in the imperiled snuffbox mussel, Epioblasma triquetra (Bivalvia: Unionidae)

Seven populations of the imperiled snuffbox mussel, Epioblasma triquetra , were sampled from across the central basin of North America. Samples were genotyped using 15 microsatellite DNA loci, and maternal history was inferred using mitochondrial DNA (mtDNA) cytochrome  c oxidase subunit-I (COI) sequences. Populations in the Clinch and St Francis rivers were quite distinct in their mtDNA. The population in the St Francis River had a unique, fixed haplotype. Among a suite of haplotypes, the population in the Clinch River had two unique haplotypes of common ancestry. The other populations were dominated by a common haplotype, which also occurred in the Clinch River population. Analysis of DNA microsatellites revealed much greater divergences and showed significant genetic structure between populations in the formerly glaciated regions. Divergence has occurred between the populations, as evidenced by moderate to high fixation indices ( F _ST and R _ST values) and nearly perfect assignment tests. These results indicate the occurrence of three glacial refugia for E. triquetra : the Tennessee River, rivers south of the Ozark Crest, and the lower Ohio River drainage near the confluence with the Mississippi. Populations in the lower Ohio River were likely to be responsible for the postglacial reinvasion into formerly glaciated regions, and into the upper Tennessee River drainage. The population of the St Francis River may constitute a distinct taxonomic entity. Conservation efforts, if necessary for this imperiled species, should not mix populations.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 371–384.     

Temperature-dependent development and reproduction of the boll weevil (Coleoptera: Curculionidae)

Abstract Effects of temperature on development, survival, and fecundity of boll weevil, Anthonomus grandis grandis Boheman, were assessed at 10, 11, 12, 15,20,25,30,35,45, and 46 °C; 65% relative humidity; and a photoperiod of 13:11 (L: D) h. The mortality of boll weevil immature stages was 100% at 12°C and decreased to 36.4% as the temperature increased to 25°C. When the temperature increased from 30 °C to 45 °C, the mortality of weevils also increased from 50.1% to 100%. From 15°C to 35°C, the bollweevilpreimaginal development rate was linearly related to temperature. The average development time of total boll weevil immature lifestages decreased 3.6-fold and the preovipositional period decreased 3.3-fold when the temperature was increased from 15°C to 30°C. The lower threshold for development was estimated at 10.9, 6.6, 7.0, and 9.0 °C for eggs, larval, pupal, and total immature stages, respectively, with total thermal time requirement to complete immature stages of 281.8 DD (degree day) (15°C) and 247.8 DD (35 °C). At 1LC and 46°C, weevil females did not oviposit. Longevity of adult females decreased 4.6-fold with increasing temperatures from 15°C to 35°C. Fecundity increased with increasing temperatures up to 30°C and significantly decreased thereafter. These findings will be useful in creating a temperature-based degree-day model for predicting the occurrence of key life stages in the field. An accurate predictor of a pest's development can be very important in determining sampling protocols, timing insecticide applications, or implementing an integrated pest management control strategy targeting susceptible life stages.     

Species diversity and community structure in neotropical fruit-feeding butterflies

Chemical secretions that are explicitly tied to species recognition may potentially be informative for phylogenetic reconstruction, especially when traditional morphological or molecular characters lack resolution. Anal sac secretions from 16 species within the family Felidae (order Carnivora) were chemically analysed and their utility as phylogenetic characters was assessed. Results were generally consistent across the different chemical data types (e.g. glycolipids, neutral lipids, or phospholipids). Two major clades were indicated, falling out according to body size: one for species greater than 30 kg (Panthera, Uncia, and Puma) and another for those less than 12 kg (remaining species). The primary solutions agreed with respect to the species pairs Prionailurus + Leptailurus, Caracal + Lynx, Oncifelis+Leopardus, Otocolobus+Felis, Panthera leo + P pardus, and P. tigris + Uncia. The only area of disagreement between chemical types was the positioning of the mountain lion (Puma concolor); however, this species appears to cluster with the cheetah (Acinonyx jubatus) in the Tjig cat clade. Although our solutions differ from six previously proposed hypotheses of felid phylogeny (morphological and molecular), the previous estimates all differ strongly amongst themselves reflecting the historical uncertainty regarding felid systematics. Phytogenies derived from the lipid data were very robust and decisive. Few equally most parsimonious trees were obtained, consistency indices were much higher than their expected values, and bootstrap and Bremer support values were also high. Thus, our findings illustrate the species-specific nature of chemical signals and their usefulness as phylogenetic characters.     

Impacts of floral gender and whole-plant gender on floral evolution in Ecballium elaterium (Cucurbitaceae)

Investigation of gender specialization in plants has led to several theories on the evolution of sexual dimorphism: reproductive compensation, based on enhanced reproductive efficiency with gender specialization (flowers should be larger on dioecious plants); Bateman's Principle, based on sex-specific selection (display for pollinator attraction in males and seed set in females); and intersexual floral mimicry, based on mimicry of a reward-providing gender by a non-reward providing gender (reduced dimorphism in dioecious plants due to increased spatial separation of male and female flowers). These theories were evaluated in Ecballium elaterium, which contains two subspecies, elaterium (monoecious) and dioicum (dioecious). Our results show that flowers of the dioecious subspecies are larger and allocate more to reproductive organs than do flowers of the monoecious subspecies. Both subspecies are sexually dimorphic (male flowers larger than female flowers). Variance in flower size among populations is greater in the dioecious subspecies. Finally, there is sufficient genetic variation to enable ongoing response to selection; genetic correlation constraints on independent response of female and male flowers may be stronger in the monoecious subspecies. Our findings provide support for aspects of all three theories, suggesting that the evolution of floral dimorphism is based on a complex interplay of factors.