Seasonal monogamy and multiple paternity in a wild population of a territorial reptile (tuatara)

Investigating the mating system of a population provides insight into the evolution of reproductive patterns, and can inform conservation management of threatened or endangered species. Combining behavioural and genetic data is necessary to fully understand the mating system and factors affecting male reproductive success, yet behavioural data are often difficult to collect for threatened species. In the present study, we use behavioural data and paternity analyses to characterize the mating system of a high density population of a long-lived, ancient reptile (tuatara, Sphenodon punctatus ). We further investigate the phenotypic traits (including body size, body condition, tail length, and ectoparasite load) that affect male reproductive success. Our behavioural data reflect a seasonally monogamous system with low levels of polyandry and polygyny that are consistent with male mate guarding. Male reproduction is highly skewed (only 25–30% of males are successful), and body size is the primary predictor of male reproductive success. Based on the genetic data, multiple paternity was found in only 8% of clutches, and the results of the paternity analyses showed monandrous clutches from socially polyandrous females. Our behavioural and genetic results revealed complexities in female mating patterns that support the potential for cryptic female choice or sperm competition. This warrants further experimental investigation into the mechanisms underlying reptile fertilization and the disparities between social and genetic polyandry in wild populations.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 161–170.     

Plasma membrane H+-ATPase-dependent citrate exudation from cluster roots of phosphate-deficient white lupin

White lupin ( Lupinus albus L.) is able to grow on soils with sparingly available phosphate (P) by producing specialized structures called cluster roots. To mobilize sparingly soluble P forms in soils, cluster roots release substantial amounts of carboxylates and concomitantly acidify the rhizosphere. The relationship between acidification and carboxylate exudation is still largely unknown. In the present work, we studied the linkage between organic acids (malate and citrate) and proton exudations in cluster roots of P-deficient white lupin. After the illumination started, citrate exudation increased transiently and reached a maximum after 5 h. This effect was accompanied by a strong acidification of the external medium and alkalinization of the cytosol, as evidenced by in vivo nuclear magnetic resonance (NMR) analysis. Fusicoccin, an activator of the plasma membrane (PM) H⁺-ATPase, stimulated citrate exudation, whereas vanadate, an inhibitor of the H⁺-ATPase, reduced citrate exudation. The burst of citrate exudation was associated with an increase in expression of the LHA1 PM H⁺-ATPase gene, an increased amount of H⁺-ATPase protein, a shift in pH optimum of the enzyme and post-translational modification of an H⁺-ATPase protein involving binding of activating 14-3-3 protein. Taken together, our results indicate a close link in cluster roots of P-deficient white lupin between the burst of citrate exudation and PM H⁺-ATPase-catalysed proton efflux.     

The RAB Family GTPase Rab1A from Plasmodium falciparum Defines a Unique Paralog Shared by Chromalveolates and Rhizaria

ABSTRACT. The RAB GTPases, which are involved in regulation of endomembrane trafficking, exhibit a complex but incompletely understood evolutionary history. We elucidated the evolution of the RAB1 subfamily ancestrally implicated in the endoplasmic reticulum-to-Golgi traffic. We found that RAB1 paralogs have been generated over the course of eukaryotic evolution, with some duplications coinciding with the advent of major eukaryotic lineages (e.g. Metazoa, haptophytes). We also identified a unique, derived RAB1 paralog, orthologous to the Plasmodium Rab1A, that occurs in stramenopiles, alveolates, and Rhizaria, represented by the chlorarachniophyte Gymnochlora stellata . This finding is consistent with the recently documented existence of a major eukaryotic clade ("SAR") comprising these three lineages. We further found a Rab1A-like protein in the cryptophyte Guillardia theta , but it exhibits unusual features among RAB proteins: absence of a C-terminal prenylation motif and an N-terminal extension with two MSP domains; and its phylogenetic relationships could not be established convincingly due to its divergent nature. Our results nevertheless point to a unique membrane trafficking pathway shared by at least some lineages of chromalveolates and Rhizaria, an insight that has implications towards interpreting the early evolution of eukaryotes and the endomembrane system.     

Linking climate change and species invasion: an illustration using insect herbivores

Climate change and invasive species are two of the most important ecological issues facing the world today. Yet, to date these two factors have largely been viewed independently. In order to prevent large-scale economic and environmental damage and as a first step towards predicting and preventing invasions, it is important to understand the factors affecting invasions. Here, we focus on insect herbivores and link the climate change and invasive research fields. We illustrate using existing published research that life history traits can be useful indicators of future invasive potential. However, climate change will also affect propagule pressure and the communities into which invaders will arrive. With the aid of a meta-analysis we show that climate-induced community changes are likely to increase niche-availability in the future, further exacerbating the problem of invasive species. It is timely and important that further research linking these two important ecological threats is undertaken.     

Reproductive traits of stream-dwelling brown trout Salmo trutta in contrasting neighbouring rivers of central Spain

1. Reproductive traits were studied in seven wild populations of resident brown trout in Spain. We examined whether growth, and certain environmental conditions such as water temperature or food abundance, could explain interpopulation variation in the reproductive characters.
2. The results indicated that nearby populations subjected to a wide variation in environmental conditions exhibited a similar reproductive performance.
3. Age distributions and sex ratios were not significantly different among populations. Age ranged from 0+ to 4+ years but the populations were dominated by the 0+ to 2+ groups. In all rivers females matured at age 2+ as opposed to age 1+ and 2+ for males. Mean length at the end of the growth period differed significantly among populations. However, annual growth rate was similar among rivers and was not significantly correlated with either biomass of the benthos or water temperature during the growth season.
4. Reproductive effort, body condition, fecundity and egg size did not correlate significantly with either the abundance of benthic invertebrates or water temperature. Once the effect of body length on both egg size and number was removed, a significant negative correlation was found between these two traits among populations.     

Faithful vertical transmission but ineffective horizontal transmission of bacterial endosymbionts during sexual reproduction of the black bean aphid,Aphis fabae

1. Insects are commonly infected with bacterial endosymbionts. In addition to the costs and benefits associated with harbouring these symbionts, their rates of vertical and horizontal transmission are important determinants of symbiont prevalence. 2. Aphids are cyclical parthenogens and show virtually perfect maternal transmission of endosymbionts during asexual reproduction. Less clear is the role of the annual sexual generation, during which overwintering eggs are produced. Data from pea aphids (Acyrthosiphon pisum Harris) suggest that maternal transmission failures and horizontal transmission via males may occur under sexual reproduction at least occasionally. No such data exist for other aphid species. 3. In the present study, the rates of maternal and paternal transmission of facultative endosymbionts during sexual reproduction in the black bean aphid, Aphis fabae (Scopoli) were examined. Crosses were performed between clones infected with Hamiltonella defensa, clones infected with Regiella insecticola and clones without facultative endosymbionts, and eggs were overwintered under three different conditions. 4. Only one of 205 offspring from crosses testing for maternal transmission failed to inherit the symbiont present in the maternal clone, and in crosses testing for horizontal transmission, only one of 412 offspring acquired a facultative symbiont from the father. 5. These results show that in A. fabae, maternal transmission of H. defensa and R. insecticola is extremely reliable also during sexual reproduction, indicating that maternal transmission failures are unlikely to exert a significant influence on frequencies of infection in the field. Paternal transmission of endosymbionts was exceedingly rare, suggesting that this route of horizontal transmission may be less important than hitherto assumed.     

Phylogeography and morphological variability in land snails: the Sicilian Marmorana (Pulmonata, Helicidae)

Land snails have long been recognized as suitable organisms for studying phenotypic differentiation and phylogeny in relation to geographical distribution. Morphological data (shell and anatomy biometry on different geographical scales) and partial sequences from mitochondrial genes (cytochrome oxidase subunit I , 16S rDNA) were used to test whether morphological patterns match phylogeny in a diversified group of Sicilian rock-dwelling land snails belonging to the genus Marmorana . The taxonomic implications of the three character sets (shell and anatomical biometry and molecular data) were also considered. The inferred phylogenetic relationships do not match morphological (shell and genitalia) patterns. This result may significantly modify the current taxonomy. Mitochondrial based reconstructions define several supported clades well correlated with geographic distribution and populations were found to be distributed parapatrically. The progressive decline in mitochondrial DNA sequence similarity over a distance of 250 km is consistent with a model of isolation by distance, a pattern previously recognized for other groups of land snails. For one clade of Marmorana , colonization along Mediterranean trade routes appears to be a possibility.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 809–823.     

Rheotaxis In Uronychia Setigera (Ciliata, Hypotrichida)

ABSTRACT. The behavior of populations of Uronychia setigera (Ciliata, Hypotrichida) exposed to water currents flowing at increasing velocities (300, 400, 500, 900, 1,700 μm/s) was analyzed using two techniques: 1) the ethogram and 2) the numerical indices recently proposed to measure the development in space and time of tracks of ciliates. Beyond a certain threshold value of the water velocity (˜ 300 μm/s), this species shows a definite positive rheotaxis, only if it moves in a more or less direct contact with the substrate. No rheotactic swimming ever occurs. Rheotaxis is a gradual, adaptive behavior: the higher the velocity of the current, the stronger the degree of the rheotactic response, as demonstrated by the increasing significance of the polar distribution of the tracks. Beyond 500 μm/s the water flow is so strong that it affects the locomotion of U. setigera continuously and strongly inducing this species to perform a new behavioral pattern, the Fast Backward Bidimensional Swimming. Under stressing water currents it reacts at first by creeping along straighter trajectories and then with faster locomotion, in such a way that its reaction is to a certain extent proportional to the drag of the currents. the rheotaxis of U. setigera is discussed as an adaptive response.