Advancing breeding phenology in response to environmental change in a wild red deer population

Most evidence for advances in phenology of in response to recent climate warming in wild vertebrate populations has come from long‐term studies of birds. Few studies have either documented phenological advances or tested their climatic causes and demographic consequences in wild mammal systems. Using a long‐term study of red deer on the Isle of Rum, Scotland, we present evidence of significant temporal trends in six phenological traits: oestrus date and parturition date in females, and antler cast date, antler clean date, rut start date and rut end date in males. These traits advanced by between 5 and 12 days across a 28‐year study period. Local climate measures associated with plant growth in spring and summer (growing degree days) increased significantly over time and explained a significant amount of variation in all six phenological traits, largely accounting for temporal advances observed in some of the traits. However, there was no evidence for temporal changes in key female reproductive performance traits (offspring birth weight and offspring survival) in this population, despite significant relationships between these traits and female phenology. In males, average antler weights increased over time presumably as a result of improved resource availability and physiological condition through spring and summer. There was no evidence for any temporal change in average male annual breeding success, as might be expected if the timing of male rutting behaviour was failing to track advances in the timing of oestrus in females. Our results provide rare evidence linking phenological advances to climate warming in a wild mammal and highlight the potential complexity of relationships between climate warming, phenology and demography in wild vertebrates.     

Electroantennogram studies of potential oviposition attractants for Toxorhynchites moctezuma and T. amboinensis mosquitoes

Abstract.Ether extracts of water samples taken from tyre sections in the field were shown to be active in electroantennogram studies with female Toxorhynchites moctezuma (Dyar & Knab) and Toxorhynchites amboinensis (Doleschall). In addition, electroantennograms were recorded from both Toxorhynchites species for seven compounds found commonly in water containing decaying leaves and known to be oviposition attractants for other mosquito species. The compounds were 4‐methylcyclohexanol, phenol, indole, 3‐methylindole, m‐ cresol, o‐ cresol and p‐ cresol. The response thresholds for these compounds ranged between 1 × 10^–4μg and 1 μg for female antennae (100 μg for male antennae). These results provide a basis for behavioural studies of oviposition attractants for the Toxorhynchites species.     

The recovery of acid‐damaged zooplankton communities in Canadian Lakes: the relative importance of abiotic,biotic and spatial variables

1. Acidification has damaged biota in thousands of lakes and streams throughout eastern North America. Fortunately, reduced emissions of sulphur dioxide and nitrogen oxides beginning in the 1960s have allowed pH levels in many affected systems to increase. Determining the extent of biological and pH recovery in these systems is necessary to assess the success of emissions reductions programmes. 2. Although there have been promising signs of biological recovery in many systems, recovery has occurred more slowly than expected for some taxa. Past studies with crustacean zooplankton indicate that a mixture of local abiotic variables, biotic variables and dispersal processes may influence the structure of recovering communities. However, most studies have been unable to determine the relative importance of these three groups of variables. 3. We assessed chemical and biological recovery of acid‐damaged lakes in Killarney Park, Ontario. In addition, we assessed the relative importance of local abiotic variables, biotic variables and dispersal processes for structuring recovering communities. We collected zooplankton community data, abiotic and biotic data from 45 Killarney Park lakes. To assess the recovery of zooplankton communities, we compared zooplankton data collected in 2005 to a survey conducted for the same lakes in 1972–73 using several univariate measures of community structure, as well as multivariate methods based on relative species abundances. To determine the factors influencing the structure of recovering zooplankton communities, we used hierarchical partitioning for univariate measures and spatial modelling and variation partitioning techniques for multivariate analyses. 4. Our survey revealed significant pH increases for the majority of sampled lakes but univariate measures of community structure, such as species richness and diversity, indicated that only minor changes have occurred in many acid‐damaged lakes. Hierarchical partitioning identified several variables that may influence our univariate measures of recovery, including pH, dissolved organic carbon (DOC) levels, fish presence/absence, lake surface area and lake elevation. 5. Multivariate methods revealed a shift in communities through time towards a structure more typical of neutral lakes, providing some evidence for recovery. Variation partitioning suggested that the structure of recovering copepod communities was influenced most by dispersal processes and abiotic variables, while biotic (Chaoborus densities, fish presence/absence) and abiotic variables were more important for cladoceran zooplankton. 6. Our results indicate that the recovery of zooplankton communities in Killarney Park is not yet complete, despite decades of emission reductions. The importance of variables related to acidification, such as pH and DOC, indicates that further chemical recovery may be necessary. The differing importance of abiotic, biotic and dispersal processes for structuring copepod versus cladoceran zooplankton might indicate that different management approaches and expectations for recovery are needed for these groups.     

Is life history a barrier to dispersal? Contrasting patterns of genetic differentiation along an oceanographically complex coast

Extreme variation in early life‐history strategies is considered a moderately good predictor of genetic subdivision and hence dispersal for a range of marine species. In reality, however, a good deal of population differentiation must reflect historical effects, more subtle variation in life histories, and, particularly, the interaction of larvae with oceanographic processes. Using a combination of allozyme and microsatellite markers, we show that the large‐scale genetic structure of populations of three species (direct and planktonically developing cushion stars and a planktonic developing sea anemone that is also asexually viviparous) varies consistently, in line with the predicted capacity for dispersal within three geographic regions. We detected high levels of genetic subdivision for the direct developing cushion star (F_ST = 0.6), low levels for the planktonically developing cushion star (F_ST = 0.009), and intermediate levels for the sexual/asexual sea anmone (F_ST = 0.19). These patterns are exhibited despite the highly variable patterns of current movement and the presence of biogeographic barriers. Our results suggest that, although there is large scale genetic differentiation for two species, patterns of population connectivity are remarkably consistent within major regions and do not reflect variation in major oceanographic processes or genetic discontinuity coincident with biogeographic boundaries. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 106–116.     

Life history of a dipteran predator (Scathophagidae: Acanthocnema) of insect egg masses in a northern California stream

1. Little is known about the predators of insect eggs in fresh waters. This study describes aspects of the life history of a scathophagid fly (Acanthocnema sp.), whose larvae are predators of aquatic insect eggs. 2. Because the Acanthocnema predator oviposits its eggs on the surface of aquatic insect egg masses, all insect egg masses were collected regularly within a 200‐m reach of Redwood Creek (California, U.S.A.) between September 2003 and June 2007. Acanthocnema predators were found predominantly within egg masses of the caddifly Neophylax rickeri (Trichoptera: Uenoidae). 3. There was a mean of 0.25 Acanthocnema individuals per N. rickeri egg mass (n = 2367 egg masses). In general, N. rickeri egg masses were more commonly found clustered in aggregations (93.7%) than singly (6.3%), and Acanthonema were found more often within the aggregations of N. rickeri (98.7%) compared to singly laid egg masses (1.3%). 4. The duration of the Acanthocnema predator life stages was: egg 2.9 ± 0.8 (mean ± SD) days, larva 15.6 ± 10.2 days, pupa 80.3 ± 24.9 days and adult 7.2 ± 4.8 days. The short duration of the Acanthocnema egg stage (1–7 days) compared to that of its prey N. rickeri (2–4 weeks) raises the probability that the undeveloped eggs of N. rickeri would be available to the young predators upon hatching. Egg consumption of N. rickeri eggs by Acanthocnema averaged 262.6 eggs per larval period. 5. Acanthocnema had a bivoltine life cycle in which the first generation fed exclusively on N. rickeri egg masses in the winter and the second generation fed on the egg masses of several species, including other Trichoptera (Brachycentridae) and Diptera (Ceratopogonidae, Chironomidae) in the spring. These findings suggest differing feeding strategies by the first and second generations of Acanthocnema in response to the seasonal availability of prey species. This type of autecological information is important for understanding mechanisms of community interactions.     

Plant and insect genetic variation mediate the impact of arbuscular mycorrhizal fungi on a natural plant–herbivore interaction

1. While both arbuscular mycorrhizal (AM) fungi and plant and insect genotype are well known to influence plant and herbivore growth and performance, information is lacking on how these factors jointly influence the relationship between plants and their natural herbivores. 2. The aim of the present study was to investigate how a natural community of arbuscular mycorrhizal fungi affects the growth of the perennial herb Plantago lanceolata L. (Plantaginaceae), as well as its interaction with the Glanville fritillary butterfly [Melitaea cinxia L. (Nymphalidae)]. For this, a multifactorial experiment was conducted using plant lines originating from multiple plant populations in the Åland Islands, Finland, grown either with or without mycorrhizal fungi. For a subset of plant lines, the impact of mycorrhizal inoculation, plant line, and larval family on the performance of M. cinxia larvae were tested. 3. Arbuscular mycorrhizal inoculation did not have a consistently positive or negative impact on plant growth or herbivore performance. Instead, plant genetic variation mediated the impact of arbuscular mycorrhizal fungi on plant growth, and both plant genetic variation and herbivore genetic variation mediated the response of the herbivore. For both the plant and insect, the impact of the arbuscular mycorrhizal community ranged from mutualistic to antagonistic. Overall, the present findings illustrate that genetic variation in response to mycorrhizal fungi may play a key role in the ecology and evolution of plant–insect interactions.     

The questionable affinities of Corsia (Corsiaceae): evidence from floral anatomy and pollen morphology

The floral anatomy and pollen morphology of Corsia are described in the context of its systematic relationships. Flowers of Corsia are epigynous, lack septal nectaries and possess a large labellum formed from the outer median tepal (sepal). The labellum is highly vascularized and has a prominent outgrowth (callus) that is apparently nectiiferous in some species of section Sessilis , although not in section Unguiculatis . The six fertile stamens are proximally fused to the style, forming a gynostemium. This combination of labellum and gynostemium is otherwise found only in Orchidaceae (Asparagales), but the orchid labellum is formed from the opposite median inner tepal, and is therefore not homologous with that of Corsia . The three genera of Corsiaceae ( Corsia , Arachnitis and Corsiopsis ) are markedly different in some respects; e.g. only Corsia has a gynostemium. However, they share a unique synapomorphy in the presence of a labellum formed from the outer median tepal (sepal). Corsia and Arachnitis are also similar in pollen sexine sculpturing. Among other putative relatives, the range of morphological similarities between Corsia and Campynemataceae (Liliales) tends to support recent preliminary inferences from molecular data that they are closely related, but a relationship with Thismia (Dioscoreales) cannot be discounted. Both Campynemataceae and Thismia share similarities with Corsia , including epigyny, absence of septal nectaries, presence of tepal nectaries, and pollen morphology. © 2002 Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 138 , 315–324.     

Nitrogen oxide gas emissions from temperate forest soils receiving long-term nitrogen inputs

From spring 2000 through fall 2001, we measured nitric oxide (NO) and nitrous oxide (N₂O) fluxes in two temperate forest sites in Massachusetts, USA that have been treated since 1988 with different levels of nitrogen (N) to simulate elevated rates of atmospheric N deposition. Plots within a pine stand that were treated with either 50 or 150 kg N ha^?1 yr^?1 above background displayed consistently elevated NO fluxes (100–200 µg N m^?2 h^?1) compared to control plots, while only the higher N treatment plot within a mixed hardwood stand displayed similarly elevated NO fluxes. Annual NO emissions estimated from monthly sampling accounted for 3.0–3.7% of N inputs to the high‐N plots and 8.3% of inputs to the Pine low‐N plot. Nitrous oxide fluxes in the N‐treated plots were generally < 10% of NO fluxes. Net nitrification rates (NRs) and NO production rates measured in the laboratory displayed patterns that were consistent with field NO fluxes. Total N oxide gas flux was positively correlated with contemporaneous measurements of NR and concentration. Acetylene inhibited both nitrification and NO production, indicating that autotrophic nitrification was responsible for the elevated NO production. Soil pH was negatively correlated with N deposition rate. Low levels (3–11 µg N kg^?1) of nitrite () were detected in mineral soils from both sites. Kinetic models describing NO production as a function of the protonated form of (nitrous acid [HNO₂]) adequately described the mineral soil data. The results indicate that atmospheric deposition may generate losses of gaseous NO from forest soils by promoting nitrification, and that the response may vary significantly between forest types under similar climatic regimes. The lowering of pH resulting from nitrification and/or directly from deposition may also play a role by promoting reactions involving HNO₂.