Mitochondrial genomes in the Hymenoptera and their utility as phylogenetic markers

Abstract.  In this study, we assessed the ability of mitochondrial genome sequences to recover a test phylogeny of five hymenopteran taxa from which phylogenetic relationships are well accepted. Our analyses indicated that the test phylogeny was well recovered in all nucleotide Bayesian analyses when all the available holometabolan (i.e. outgroup) taxa were included, but only in Bayesian analyses excluding third codon positions when only the hymenopteran representatives and a single outgroup were included. This result suggests that taxon sampling of the outgroup might be as important as taxon sampling of the ingroup when recovering hymenopteran phylogenetic relationships using whole mitochondrial genomes. Parsimony analyses were more sensitive to both taxon sampling and the analytical model than Bayesian analyses, and analyses using the protein dataset did not recover the test phylogeny. In general, mitochondrial genomes did not resolve the position of the Hymenoptera within the Holometabola with confidence, suggesting that an increased taxon sampling, both within the Holometabola and among outgroups, is necessary.     

Revision of the Euthalia phemius complex (Lepidoptera: Nymphalidae) based on morphology and molecular analyses

Adults of the Euthalia phemius complex, which is composed of three South‐East Asian nymphalid species, Euthalia phemius, Euthalia ipona, and Euthalia euphemia, were genetically analysed by examining mitochondrial and nuclear genes. The E. phemius complex was also examined morphologically, with particular emphasis on wing markings and male genitalia. No significant differences amongst the three species in the complex were detected with respect to either genetic distance or genital morphology. We therefore conclude that the three currently recognized Euthalia species belong to a single species. Accordingly, E. ipona is synonymized with E. phemius. Euthalia euphemia is treated as a subspecies of E. phemius. Type specimens of all taxa and a synonymic list for the E. phemius complex are also given. In addition, we briefly discuss the evolution and biogeography of the species complex. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 164 , 304–327.     

Habitat attributes associated with short‐term settlement of Ozark hellbender (Cryptobranchus alleganiensis bishopi) salamanders following translocation to the wild

1. Organisms associated with lotic systems rank among the most threatened because of global change. Although translocation is being increasingly applied as a conservation strategy, most studies have focused on survival and recruitment of individuals, and few have attempted to identify how habitat attributes influence short‐term settlement of animals during the critical post‐release period. 2. We demonstrate the application of resource selection modelling in an information theoretic framework to identify release‐site characteristics that will increase the likelihood of settlement for a fully aquatic benthic stream salamander, the Ozark hellbender (Cryptobranchus alleganiensis bishopi). We fit discrete choice models using data from 29 radio‐tagged hellbenders that were translocated to two sites in the North Fork of the White River (NFWR), Missouri (U.S.A.). We defined resource availability at two spatial scales (stream reach and home range) and quantified abiotic habitat attributes at 3181 salamander locations and 6329 random available locations collected between May 2008 and August 2009. 3. At both sites and spatial scales, a single model received substantially greater support (0.96–1.00 of total model weight) than all other models, and top‐ranked models were similar in form and predictive ability. At both spatial scales, selection was positively influenced by the presence of cobble‐boulder substratum relative to bedrock and finer substrata. We also noted a negative interactive effect between distance to the nearest substratum particle large enough to provide cover (i.e. at least one axis ≥15 cm in length) and an increase in either a direct or relative (i.e. pool, run, and riffle) measure of water velocity. 4. Collectively, salamanders released in our study selected resources indicative of long‐term benthic microhabitat stability. However, despite strong selection of cobble‐boulder substratum, 8% (282 of 3181) of captive‐reared hellbender locations occurred in bank crevices and root masses. Although several studies have reported the importance of near bed hydraulics in determining occurrence of stream macroinvertebrates, our findings are the first to indicate that spacing among cobble‐boulder substrata may be important for hellbenders. 5. To increase the likelihood of short‐term settlement of captive‐reared hellbenders in the wild, we recommend prioritising release sites where the average distance between cobble‐boulder particles within habitat patches is minimised. In general, average spacing among cobble and boulder substrata should be <1 m in habitat patches where mean benthic water velocity exceeds 0.1 m s^?1, and <0.5 m where water velocity approaches 0.30 m s^?1. Based on home range sizes of captive‐reared Ozark hellbenders, the collective extent of suitable cobble‐boulder habitat patches within release sites should approximate at least 10 m² per salamander released.     

Responses of lotic periphyton to pulses of phosphorus: P‐flux controlled growth rate

1. The response of stream periphyton to the addition of limiting nutrients has been the focus of many studies. However, the influence of pulsed nutrient additions has not previously been examined. This study investigates the biomass accrual and physiological responses of phosphorus‐limited lotic periphyton to hourly phosphate fluxes. 2. Two pulsing experiments were conducted: (i) a variable flux trial that compared variable hourly P‐fluxes, delivered either continuously at different concentrations or at the same concentration but in pulses of differing duration per hour and (ii) a constant flux trial that compared periphyton responses at a set hourly P‐flux but delivered in pulses of varying concentration and duration. 3. Growth response and alkaline phosphatase activity during the variable flux experiment showed that periphyton responds to the hourly integrated flux of phosphorus, regardless of whether the nutrient is supplied in short concentrated pulses or continuously at much lower concentrations. 4. The constant flux experiment examined the pulse period required to attain maximum biomass for a given phosphorus flux. Periphyton response to 5‐min pulses of phosphate per hour approximated the maximum biomass as that attained when the same hourly flux was added continuously. Compared with the control, there was also a substantial increase in biomass with pulses of only 1 min each hour. These results demonstrate that the hourly average phosphate concentration to which periphyton communities are exposed is paramount in determining P‐limited growth dynamics. 5. Species composition was not significantly different among treatments in each experiment; however, the design was to evaluate monotonic response with increasing phosphorus flux and species diversity may not respond monotonically. The data are therefore preliminary but suggest the need to determine if species diversity is generally lower when there are brief pulses of phosphate. Unlike pulse experiments that mimic lentic situations, nutrient additions were not used to completion and species success and composition was more dependent on their ability to acquire limiting nutrients rapidly rather than on their ability to take up nutrients at the lowest concentration.     

Foraging guild membership explains variation in waterbird responses to the hydrological regime of an arid‐region flood‐pulse river in Namibia

1. Little is known about hydrological influences on tropical waterbird communities. We used a 16‐year data set (1991–2007) of waterbird censuses, together with a classification of observed species into foraging guilds, to explore the relationships between natural variations in flow regime, foraging guild and the community composition of waterbirds at the Okavango River in the Caprivi Strip of north‐eastern Namibia, southern Africa. 2. We addressed three hypotheses to explain variation in waterbird community composition: (i) exploitation (birds move towards resource‐rich patches to exploit periods of high food abundance); (ii) escapism (declines in regional habitat quality force birds to aggregate in perennial waterbodies); and (iii) interaction (bird assemblages are dominated by intra‐ and interspecific interactions, such as flock formation for breeding or moulting, that can be explained better by life history demands or competition than by resource availability). 3. Waterbirds in different foraging guilds responded strongly but at different periods to changes in the hydrological environment, creating a complex but predictable successional pattern in community composition through time. Deep‐water feeders responded fastest (abundance peaking 2 months post‐flood), followed by shallow‐water feeders (4 months) and emergent vegetation feeders (7 months). Species that forage on short vegetation or in mud showed a bimodal response with peaks in abundance at 3 and 8 months post‐flood. 4. Our results indicated a strong effect of the local flow regime and hence supported the exploitation hypothesis. The foraging guild approach allowed us to identify clear patterns in a highly complex ecosystem and shows considerable promise as an analytical tool for similar data sets. Our results further suggest that while the entire bird community will be affected by hydrological alterations such as impoundments, water extraction and climate change, deep‐water feeders may be one of the most vulnerable groups.     

Using Resource Selection Functions to Improve Estimation of Elk Population Numbers

Abstract: Stratification is commonly used to improve sampling efficiency of aerial surveys of ungulate populations with strata typically based on a priori information, such as preflight animal observations or vegetation attributes as surrogates for animal densities. We evaluated the usefulness of stratifying survey units for elk (Cervus elaphus) in the Rocky Mountain foothills of Alberta, Canada, using a resource selection function (RSF). We compared precision and design efficiency (DEFF) of population estimates from stratification approaches based on an RSF model to the past approach using amount of forest cover. We used a sample of telemetry relocations taken over a 3-year period from 165 elk, rarified to times of the day and months of the year when aerial surveys are conducted, to develop the RSF. We then used the top RSF model, based on Akaike's Information Criterion, to derive the average RSF value for an 8-km² survey unit. Using survey data from the first year, we evaluated binning schemes to define RSF-oriented strata based on poststratification and showed that Jenks natural breaks in the RSF values provided the greatest improvement in DEFF and increased precision, compared to 2 other stratification schemes. We then used this approach with data from 2 additional surveys to find that stratification by RSF consistently improves relative precision and design efficiency of elk population estimates, whether we employ pre- or poststratification. Where a RSF is available it could be used as a surrogate for animal densities when conducting stratified sampling for population surveys.