Using a Centrality Index to Determine the Contribution of Restored and Volunteer Plants in the Restoration of Plant-Pollinator Mutualisms on a Reclaimed Strip Mine
Sarah Cusser, Karen Goodell. 2014. Ecological Restoration 32, 179-188. DOI: 10.3368/er.32.2.179
Abstract The restoration of ecosystem function relies, at least partly, on restoring services provided by mutualists. If the goal of restoration is to assemble functional and stable communities, particular care should be taken to identify and attract those species that contribute most to long-term community stability. Land managers and ecologists can use centrality indices, a group of network statistics that measure the relative importance of individuals within a community, to objectively determine the contribution of particular plant species to overall restoration efforts. Our objective was to compare the role of flowers planted as part of the restoration effort to those plants volunteering at the restoration site, either native adventives or non-native invaders, in support of the pollinator community. Further, we sought to determine how this relationship varied with changes in relative floral abundance. We found that plants cultivated as part of the restoration effort were preferred by pollinators, attracted the greatest abundance and richness of pollinators, and were the most central in our plant-pollinator networks compared to volunteers, despite the greater abundance of volunteer plants across the site. We also found that the role of all plants was density dependent; plants of every group attracted more pollinators in plots where they had greater relative abundance. We conclude that centrality indices provide a tool for planning and monitoring the restoration of important functional relationships and allow land managers and ecologists to objectively determine the contribution of particular plants to overall community structure and function.
Life history traits of adults and embryos of the Antarctic midge Belgica antarctica
Eri Harada, Richard E. Lee Jr., David L. Denlinger, Shin G. Goto. 2014. Polar Biology in press. DOI: 10.1007/s00300-014-1511-0
Abstract Although larvae of the Antarctic midge, Belgica antarctica, live for more than 2 years, the adult and embryonic stages are brief and are less well known than the larvae. In this report, we provide additional details of these understudied life stages with laboratory observation on adult emergence, longevity, preoviposition period and embryonic development. Male adults emerged slightly earlier than females, and they also lived longer. More than a half (57 %) of the adults that emerged in the laboratory were males. Females produced only a single egg mass and died within a day after oviposition. Embryonic development required 16 days at 4 °C, and prior to hatching, the pharate larvae perform a distinct sequence of behaviors that include drinking and peristaltic movement. We also discuss points that need to be resolved for laboratory propagation of this species.
Exotic Mussels Turning Ecosystems Upside Down
Christine M. Mayer, Lyubov E. Burlakova, Peter Eklöv, Dean Fitzgerald, Alexander Y. Karatayev, Stuart A. Ludsin, Scott Millard, Edward L. Mills, A. P. Ostapenya, Lars G. Rudstam, Bin Zhu, and Tataina V. Zhukova. 2014. Quagga and Zebra Mussels: Biology, Impacts, and Control. Second Edition. Taylor and Francis, New York. 816 pp.
Abstract Many north-temperate lakes are experiencing a shift in energy production from the open pelagic to the benthic region. This process termed “benthification” is occurring across lakes due to increased water clarity. Benthification alters habitats within aquatic ecosystems by augmenting benthic produc- tion and escalating the flow of energy and materials between the pelagic and benthic subsystems. Two anthropogenically driven factors, reduced phosphorus inputs and filter feeding by nonindigenous species (i.e., zebra and quagga mussels, Dreissena polymorpha and Dreissena rostriformis bugensis, respectively), can both enhance water clarity. However, long- term data from seven lakes in North America and Europe indicate that dreissenids are driving benthification more than nutrient reductions. Therefore, ecosystem engineering by these two nonindigenous species is changing the fundamen- tal, physical nature of an entire category of ecosystems.
Evolutionary basis of mitonuclear discordance between sister species of mole salamanders (Ambystoma sp.)
Robert D. Denton, Laura J. Kenyon, Katherine R. Greenwald and H.Lisle Gibbs. 2014. Molecular Ecology in press. DOI: 10.1111/mec.12775
Abstract Distinct genetic markers should show similar patterns of differentiation between species reflecting their common evolutionary histories, yet there are increasing examples of differences in the biogeographic distribution of species-specific nuclear (nuDNA) and mitochondrial DNA (mtDNA) variants within and between species. Identifying the evolutionary processes that underlie these anomalous patterns of genetic differentiation is an important goal. Here, we analyse the putative mitonuclear discordance observed between sister species of mole salamanders (Ambystoma barbouri and A. texanum) in which A. barbouri-specific mtDNA is found in animals located within the range of A. texanum. We test three hypotheses for this discordance (undetected range expansion, mtDNA introgression, and hybridization) using nuDNA and mtDNA data analysed with methods that varied in the parameters estimated and the timescales measured. Results from a Bayesian clustering technique (structure), bidirectional estimates of gene flow (migrate-n and IMa2) and phylogeny-based methods (*beast, bucky) all support the conclusion that the discordance is due to geographically restricted mtDNA introgression from A. barbouri into A. texanum. Limited data on species-specific tooth morphology match this conclusion. Significant differences in environmental conditions exist between sites where A. texanum with and without A. barbouri-like mtDNA occur, suggesting a possible role for selection in the process of introgression. Overall, our study provides a general example of the value of using complimentary analyses to make inferences of the directionality, timescale, and source of mtDNA introgression in animals
How Much Cleaning is Needed When Processing Otoliths from Fish Larvae for Microchemical Analysis?
Theodore R. Gover, Megan K. Nims, Jason J. Van Tassell, Paris D. Collingsworth, John W. Olesik, Stuart A. Ludsin & Elizabeth A. Marschall. 2014. Transactions of the American Fisheries Society 143, 779-783. DOI:
Abstract Otolith microchemistry is a widely used tool in fish ecology and fisheries management. Cleaning-protocol assessments are lacking, however, especially for larval fish otoliths, which are more fragile and difficult to manipulate than larger otoliths. Herein, we assess the value of cleaning larval fish otoliths with sonication, a commonly used technique that is time consuming and risks loss or breakage of small otoliths, as well as with a lesser-known technique using a low-power laser cleaning pulse (LPLCP). We measured trace elements in larval Walleye Sander vitreus reared in different water strontium concentrations. Strontium and Ba did not differ among any cleaning treatments, indicating that neither sonication nor a LPLCP is necessary. Likewise, Mn did not differ between sonicated and nonsonicated treatments; however, Mn was lower when a LPLCP was used. We suggest omitting the sonication step when preparing otoliths for trace element analysis of Sr, Ba, Mn, and other trace elements found in high abundances. The addition of a LPLCP is useful, although more research in this arena is warranted. Our findings should greatly reduce otolith processing time and the risk of losing and breaking larval otoliths during the cleaning process.
Identifying natal origins of spawning adult sea lamprey (Petromyzon marinus): Re-evaluation of the statolith microchemistry approach.
A Lochet, BJ Fryer, SA Ludsin, EA Howe, JE Marsden. 2014. Journal of Great Lakes Research, in press. DOI: 10.1016/j.jglr.2014.04.014.
Abstract Identifying the stream of origin of spawning-phase sea lamprey (Petromyzon marinus) is crucial to improve the control of this nuisance species in the Laurentian Great Lakes and Lake Champlain. Recently, Howe et al. (2013) found a poor accuracy in the natal origin assignment of 33 spawning adults of known-origin from the Lake Champlain watershed using the statoliths from larvae captured in their natal streams to develop discriminant functions. Herein, we revisited the natal origin assignment of the same sample of adults, this time using the statoliths from newly-metamorphosed sea lampreys (transformers) captured in their natal stream. Using laser-ablation inductively coupled plasma-mass spectrometry, 216 transformers originating from 11 Lake Champlain tributaries were successfully discriminated with a classification accuracy of 78% (range: 40-100%), with rubidium (Rb) and strontium (Sr) as the most discriminating elements. However, the assignment to the correct (known) natal origin for adults was poor. While the majority of adults were known to originate from Lewis and Malletts creeks, our maximum likelihood procedure did not assign any adults to these streams. Such result might be explained by temporal and analytical variability of elemental signatures and by a mismatch in Rb concentrations between transformers and adults probably due to physiological effects. We do not recommend the use of statolith microchemistry to classify adults to a natal tributary when Rb is considered as a discriminating element until we can understand and predict the shift in Rb between metamorphosis and the spawning adult life stage.
Sex and social status affect territorial defence in a cooperatively breeding cichlid fish, Neolamprologus savoryi
Kelly A. Garvy, Jennifer K. Hellmann, Isaac Y. Ligocki, Adam R. Reddon, Susan E. Marsh-Rollo, Ian M. Hamilton, Sigal Balshine, Constance M. O’Connor. 2014. Hydrobiologia in press. DOI: 10.1007/s10750-014-1899-0
Abstract Members of social groups must defend their shared territory against both predators and competitors. However, individuals differ widely in their contributions to territorial defence. Assessing the variation in response to territorial intrusions provides insight into both the benefits and costs of group living for different group members. In this study, we assessed the response of wild Neolamprologus savoryi to experimentally staged territorial intrusions. Neolamprologus savoryi is an understudied cooperatively breeding cichlid fish endemic to Lake Tanganyika, East Africa. We found that dominant male and dominant female N. savoryi were both highly aggressive towards heterospecific predators and towards same-sex conspecific rivals. Both dominant males and females were less aggressive towards opposite-sex conspecific opponents, with the relative reduction in aggression being most pronounced in males. Subordinates provided low levels of defence against all intruder types, which suggests that subordinate N. savoryi rely on larger group members for protection. Collectively, our results provide insight into the structure and function of N. savoryi social groups, and highlights key costs and benefits of cooperation for individual social group members.
Cryptic and Overlooked: Species Delimitation in the Mycoheterotrophic Monotropsis (Ericaceae: Monotropoideae)
Jeffrey P. Rose and John V. Freudenstein. 2014. Systematic Botany 39, 578-593. DOI: 10.1600/036364414X680762
Abstract Most recent treatments of Monotropsis recognize a single species of achlorophyllous, mycoheterotrophic herbs endemic to the southeastern U. S. A. (M. odorata), although four species have been described. This study reevaluates these proposed taxa using a comprehensive approach to species delimitation analyzing variation in morphology, phenology, geography, nuclear DNA, and chloroplast DNA. Principal components analysis of morphometric data reveals two clusters that are geographically distinct. These groups correspond to clades resolved with nuclear (ITS/26S and Xdh) and plastid (rpl32-trnL) DNA that are furthermore distinct phenologically. These data support recognition of M. reynoldsiae, a Florida endemic and M. odorata, an Appalachian endemic. Monotropsis lehmaniae, proposed based on an autumn flowering period and supposed floral differences, is shown to comprise individuals that are not yet in anthesis, and should not be recognized. Cryptophila pudica, named based on its disjunct geographical distribution and floral differences, is also shown to be indistinct. A taxonomic revision of the genus is presented.