Common reptiles unaffected by connectivity or condition in a fragmented farming landscape

Abstract Species need to disperse at a broad range of spatial scales, the recognition of which has spawned programmes such as Wildlands and WildCountry that aim to restore large‐scale connectivity. To achieve connectivity, a first step is to understand how wildlife uses existing remnants. In this study we examine the effect of remnant isolation and condition on the reptile fauna of fragmented mallee habitats in southern Australia. In three replicate landscapes we use pitfall traps to survey reptiles in five landscape elements: Conservation Park, connected, disconnected and isolated fragments, and the agricultural matrix. Reptile species richness, abundance, abundance of snakes, skinks and the 10 most common species had no significant association with landscape elements, excluding the matrix. This was despite a substantial reduction in plant species richness in the fragments, particularly of shrubs. Only seven individual reptiles were captured in the matrix, most on one site with deep sandy soils. The farmland on clay soils appeared to be relatively impermeable for reptiles, although four species could traverse 100 m of cleared sand‐dune. The lack of an isolation effect suggests that populations in remnants are persistent, or that occasional dispersal by common reptiles maintains populations. In contrast with common species, fewer rare species were captured in remnants compared with the Conservation Park, implying that some species may be entirely excluded from the remnants. Our study suggests that the spatial configuration and condition of the fragments sustain populations of many common reptile species. Remnants will therefore be invaluable as attempts are made to restore landscape‐scale permeability. However, additional conservation effort should be made to restore plant species that have been lost from the agricultural landscape. Future research should aim to better define the suite of reptile species that may not be able to use the remnants at all.     

Male-limited evolution suggests no extant intralocus sexual conflict over the sexually dimorphic cuticular hydrocarbons of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

Sexually dimorphic traits are likely to have evolved through sexually antagonistic selection. However, recent empirical data suggest that intralocus sexual conflict often persists, even when traits have diverged between males and females. This implies that evolved dimorphism is often incomplete in resolving intralocus conflict, providing a mechanism for the maintenance of genetic variance in fitness-related traits. We used experimental evolution in Drosophila melanogaster to directly test for ongoing conflict over a suite of sexually dimorphic cuticular hydrocarbons (CHCs) that are likely targets of sex-specific selection. Using a set of experimental populations in which the transmission of genetic material had been restricted to males for 82 generations, we show that CHCs did not evolve, providing experimental evidence for the absence of current intralocus sexual conflict over these traits. The absence of ongoing conflict could indicate that CHCs have never been the target of sexually antagonistic selection, although this would require the existing dimorphism to have evolved via completely sexlinked mutations or as a result of former, but now absent, pleiotropic effects of the underlying loci on another trait under sexually antagonistic selection. An alternative interpretation, and which we believe to be more likely, is that the extensive CHC sexual dimorphism is the result of past intralocus sexual conflict that has been fully resolved, implying that these traits have evolved genetic independence between the sexes and that genetic variation in them is therefore maintained by alternative mechanisms. This latter interpretation is consistent with the known roles of CHCs in sexual communication in this species and with previous studies suggesting the genetic independence of CHCs between males and females. Nevertheless, direct estimates of sexually antagonistic selection will be important to fully resolve these alternatives.     

Patterns of divergence in the olive sunbird Cyanomitra olivacea (Aves: Nectariniidae) across the African rainforest–savanna ecotone

In the debate over modes of vertebrate diversification in tropical rainforests, two competing hypotheses of speciation predominate: those that emphasize the role of geographical isolation during glacial periods and those that stress the role of ecology and diversifying selection across ecotones or environmental gradients. To investigate the relative roles of selection versus isolation in refugia, we contrasted genetic and morphologic divergence of the olive sunbird (Cyanomitra olivacea) at 18 sites (approximately 200 individuals) across the forest–savanna ecotone of Central Africa in a region considered to have harboured three hypothesized refugia during glacial periods. Habitats were characterized using bioclimatic and satellite remote‐sensing data. We found relatively high levels of gene flow between ecotone and forest populations and between refugia. Consistent with a pattern of divergence‐with‐gene‐flow, we found morphological characters to be significantly divergent across the gradient [forest versus ecotone (mean ± SD): wing length 60.47 ± 1.81 mm versus 62.18 ± 1.35 mm; tarsus length 15.51 ± 0.82 mm versus 16.00 ± 0.57 mm; upper mandible length 21.77 ± 1.09 mm versus 23.19 ± 0.98 mm, respectively]. Within‐habitat comparisons across forest and ecotone sites showed no significant differences in morphology. The results show that divergence in morphological traits is tied to environmental variables across the gradient and is occurring despite gene flow. The pattern of divergence‐with‐gene‐flow found is similar to that described for other rainforest species across the gradient. These results suggest that neither refugia, nor isolation‐by‐distance have played a major role in divergence in the olive sunbird, although ecological differences along the forest and savanna ecotone may impose significant selection pressures on the phenotype and potentially be important in diversification. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 821–835.     

Elevationally biased avian predation as a contributor to the spatial distribution of geometrid moth outbreaks in sub‐arctic mountain birch forest

1. Population dynamics and interactions that vary over a species' range are of particular importance in the context of latitudinal clines in biological diversity. Winter moth (Operophtera brumata) and autumnal moth (Epirrita autumnata) are two species of eruptive geometrids that vary widely in outbreak tendency over their range, which generally increases from south to north and with elevation. 2. The predation pressure on geometrid larvae and pupae over an elevational gradient was tested. The effects of background larval density and bird occupancy of monitoring nest boxes on predation rates were also tested. Predation on larvae was tested through exclusion treatments at 20 replicate stations over four elevations at one site, while pupae were set out to measure predation at two elevations at three sites. 3. Larval densities were reduced by bird predation at three lower elevations, but not at the highest elevation, and predation rates were 1.9 times higher at the lowest elevation than at the highest elevation. The rate of predation on larvae was not related to background larval density or nest box occupancy, although there were more eggs and chicks at the lowest elevation. There were no consistent differences in predation on pupae by elevation. 4. These results suggest that elevational variation in avian predation pressure on larvae may help to drive elevational differences in outbreak tendency, and that birds may play a more important role in geometrid population dynamics than the focus on invertebrate and soil predators of previous work would suggest.     

Action Potentials in Lupinus angustifolius L. Shoots: II. DETERMINATION OF THE STRENGTH-DURATION RELATION AND THE ALL-OR-NOTHING LAW

In Lupinus shoots an electrical stimulus (d.c.) produces a potentialwave analogous to the action potential wave (AP) in stimulatedsimple plant cells or in nerves. The method used (Paszewskiand Zawadzki, 1973a, b) is similar to those applied in neurophysiologyin research on the excitability of nerves. In the present paper the strength-duration relation (Eqn. (1))of the excitation in Lupinusitalic has been used to calculatethe values of the rheobase, chronaxie, and useful time of pulse.The rheobase, as a threshold value of the stimulus, is examinedin terms of the applicability of the all-or-nothing law. The results suggest that the origin and propagation of AP inplants and in nerves may occur in a similar way. The analogybetween the impulse propagation in nerve trunks and in Lupinusshoots is discussed.     

Cryptic hybrids between Pinus uncinata and P. sylvestris

We tested the performance of molecular markers and biometric traits in the identification of hybrids between closely related mountain pine (Pinus uncinata) and Scots pine (Pinus sylvestris). A plastid DNA marker and a set of morphological and anatomical needle traits were applied in analyses of individuals from several sympatric stands of the species and a single‐species' population from southern Europe, used as a reference. A polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) marker from the plastid trnL–trnF region and morphological and anatomical traits clearly discriminated between the pure species. Significant differences were found between P. uncinata and P. sylvestris, mostly in the shape of epidermal cells and the number of stomata. Four putative hybrids with P. sylvestris morphology, but with P. uncinata plastid DNA haplotypes, were found in a population from Sierra de Gúdar near Valdelinares, the southernmost locality of the latter species in eastern Spain. Discrimination analyses between and within populations placed these individuals on the edge of an agglomeration of P. sylvestris individuals. The results suggest that hybridization between the species is rare, but can result in cryptic hybrids morphologically similar to the maternal species. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163 , 473–485.     

Diurnal Habitat Relationships of Canada Lynx in an Intensively Managed Private Forest Landscape in Northern Maine

Abstract In March 2000, Canada lynx (Lynx canadensis) were listed as a federally threatened species in 14 states at the southern periphery of their range, where lynx habitat is disjunct and snowshoe hare (Lepus americanus) densities are low. Forest conditions vary across lynx range; thus, region-specific data on the habitat requirements of lynx are needed. We studied lynx in northern Maine, USA, from 1999 to 2004 to assess quality and potential for forests in Maine to sustain lynx populations. We trapped and radiocollared 43 lynx (21 M, 22 F) during this period and evaluated diurnal habitat selection by 16 resident adult lynx (9 M, 7 F) monitored in 2002. We evaluated lynx selection of 8 habitats at multiple spatial scales, and related lynx habitat selection to snowshoe hare abundance. Lynx preferred conifer-dominated sapling stands, which supported the highest hare densities on our study site (x̄ = 2.4 hares/ha), over all other habitats. The habitats where lynx placed their home ranges did not differ by sex. However, within their home ranges, males not only preferred conifer-dominated sapling stands, but also preferred mature conifer, whereas females singularly preferred conifer-dominated sapling stands. Approximately one-third of Maine's spruce-fir forest and nearly 50% of our study area was regenerating conifer or mixed-sapling forest, resulting from a disease event and intensive forest management (e.g., large clear-cuts). Our findings suggest that current habitat conditions in Maine are better than western montane regions and approach conditions in boreal forests during periods of hare abundance. We recommend that forest landowners maintain a mosaic of different-aged conifer stands to ensure a component of regenerating conifer-dominated forest on the landscape.     

The Fabrication of H+-Selective Liquid-Membrane Micro-electrodes for Use in Plant Cells

The hydrogen ion-sensitive liquid-membrane micro-electrode,as described by Amman, Lanter, Steiner, Schulthess, Shijo, andSimon (1981) has been developed further and made applicablefor turgescent plant cells even with tough cell walls, by treatmentwith polyvinylchloride (PVC). Such an electrode is slower (t=5–10s) than the untreated electrode (t=2–6 s), but displays55–59 mV/pH-unit between pH 4·3 and 9·0,and is almost insensitive towards different buffers and K⁺.The electrodes are usable on more than one cell and have stillgood recalibration properties. Testing the electrodes on 11different cell types of Riccia fluitans, Sinapis alba, Zea mays,Avena sativa, Kalanchöe daigremontiana, Lemna gibba andChara corallina, we find the internal pH slightly alkaline (7·1–7·6)in ten cases (exception: old rhizoids of Riccia, pH₁=4·8).From that we conclude that the pH-electrode measures in thecytosol. According to the different plant material, severalprocedures for internal pH-measurements are presented and supportedby data: Application of cyanide and acetic acid causes internalacidification. Light-off transiently alkalinazes, light-on transientlyacidifies the internal pH. The advantages and limitations ofthe method are critically discussed, and it is concluded thatthis electrode is a powerful tool in plant physiology. Key words: Internal pH, pH-sensitive micro-electrode     

Phylogeny and evolution of phytophagous ladybird beetles (Coleoptera: Coccinellidae: Epilachnini), with recognition of new genera

Phytophagous ladybird beetles of the tribe Epilachnini are a cosmopolitan, species‐rich group of significant economic importance as pests of agricultural crops. The tribe is well characterized morphologically and clearly monophyletic, but very little is known about its internal phylogenetic relationships and their genus‐level taxonomy. In order to infer the evolutionary history of Epilachnini, test its monophyly and provide a phylogeny‐based classification, we assembled a comprehensive dataset, consisting of four DNA markers (18S and 28S rRNA and 16S, COI mtDNA) and a matrix of 104 morphological characters for 153 species of Epilachnini representing all previously recognised genera, ～11% of the known species, and 14 outgroup taxa. Molecular, morphological and combined datasets were analysed using maximum likelihood, parsimony and Bayesian inference. Bayes factors and Approximately Unbiased tests (AU) were used to compare alternative phylogenetic hypotheses of unconstrained and backbone‐constrained analysis. Only 14 of the 25 included genera were recovered monophyletic, as originally defined. Afidentula Kapur, Afidenta Dieke, Afissula Kapur, Epilachna Chevrolat, Henosepilachna Li Toxotoma Weise and Mada Mulsant are shown to be poly‐ or paraphyletic; Chnootriba Chevrolat, Subafissa Bielawski, Lalokia Szawaryn & Tomaszewska and Papuaepilachna Szawaryn & Tomaszewska form monophyletic groups within larger clades of genus level. All of these genera are redefined here. The two largest genera of Epilachnini, Epilachna Chevrolat and Henosepilachna Li were represented by multiple monophyletic clades, which we described as new genera: Chazeauiana Tomaszewska & Szawaryn gen.n. ; Diekeana Tomaszewska & Szawaryn gen.n .; Fuerschia Tomaszewska & Szawaryn gen.n. and Ryszardia Tomaszewska & Szawaryn gen.n . The following new synonyms are proposed: Afissa Dieke (=Afissula Kapur); Henosepilachna Li in Li & Cook (=Subafissa Bielawski); Papuaepilachna Szawaryn & Tomaszewska (=Lalokia Szawaryn & Tomaszewska). This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:440E7FA4‐C859‐47E0‐8335‐30D478CBA8FA .     

Opportunities for mate choice in the fission‐performing ant Cataglyphis cursor

1. Sexual selection has been little studied in social insects. Nonetheless, because mating is generally for life, opportunities for selecting among mating partners should be exploited. 2. In some ants, males aggregate at nest entrances to mate with emerging gynes. Both males and females thus have access to multiple mates over a relatively protracted period, giving rise to opportunities for mate choice and multiple mating. 3. We provide data from field observations of the male mating biology of the ant, Cataglyphis cursor Fonscolombe. In this species, females mate with, on average, six males each at the nest entrance and found colonies with the help of workers. 4. Males were present at the field site for approximately 1 month in spring, with up to 40 males at a single nest entrance for, on average, 4.7 days. Individual males were observed to survive up to 3 days, and mate up to eight times. 5. Thus both males and females of this species have the ability to mate multiply and have a window permitting mate choice to occur. Workers actively attacked males and may take part in the mate choice process, making C. cursor an interesting model to study questions relating to sexual selection and male mating strategies.