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Habitat Preference of the Daggerblade Grass Shrimp Palaemonetes pugio and Whether Field Preference is Correlated with the Trematode Parasite Microphallus turgidus
Full text linkDaggerblade grass shrimp Palaemonetes pugio reside in brackish estuarine systems and are thus exposed to the parasitic trematode Microphallus turgidus. The purpose of this study was to determine if the infection of P. pugio by M. turgidus was different across months and between two sites near Savannah, GA, and to determine habitat preference of infected P. pugio between the invasive red alga Gracilaria vermiculophylla and substrate-free open space in the laboratory. Trematode density was significantly higher in October-December 2016 and February 2017 (11.0-13.3) at one site and was significantly higher December 2016-January 2017 (10.1-10.3) and August-October 2017 (10.8-12.6) at the other site. In the laboratory, 76% of shrimp preferred tank edge locations whereas only 20% preferred G. vermiculophylla. Only 4% consistently selected the substrate-free open space. A wide range of factors such as food availability, presence of predators, interspecies competition, and abiotic conditions perhaps influence changes in parasite density and habitat preference
Examining Stock Structure of Common Bottlenose Dolphins (Tursiops Truncatus) through Photo-Identification and Genetic Analyses
Full text linkCetaceans range over large distances resulting in complex patterns of population structure. The coastal ecotype of common bottlenose dolphins (Tursiops truncatus) often consists of distinct groups that exhibit localized adaptations on small spatial scales that result in fine scale genetic structuring. Sex-specific home range patterns are common in cetacean species and may differ between geographic locations. The purpose of this study was to couple long-term photo-identification data with genetics to examine stock structure and to measure home range size of male and female common bottlenose dolphins in the estuarine waters around Savannah, GA. The study area was categorized into three segments: a) a north region, b) a buffer region, and c) a south region. Remote biopsy sampling was conducted in September 2015 and February and March 2017. No significant difference was found when regions were compared by sample location only (n=69). After animals without ≥10 sightings (n=45) were excluded from analysis, a significant difference in FST was found between the north versus buffer (p=0.0147). When the animals with ≥10 sightings were placed in the location with 50% or more of their sightings, a significant difference in in FST was found between the north versus buffer and north versus south (p=0.0018 and p=0.0164). With the addition of sighting history data, stronger subdivision was found between populations. No significant difference was found in minimum convex polygon home range size of males (105.34 ± 49.28 km2; n=24) and females (109.83 ± 53.29 km2; n=57) or in kernel density home range size. The addition of supplemental data, such as photo-identification, to a genetic analysis, can provide additional insight into stock structure. Methods used in this study could be employed by future studies to improve understanding of the complex stock structure of common bottlenose dolphins in estuarine waters
Take me where I want to go: Institutional prestige, advisor sponsorship, and academic career placement preferences
Full text linkPlacement in prestigious research institutions for STEM (science, technology, engineering, and mathematics) PhD recipients is generally considered to be optimal. Yet some doctoral recipients are not interested in intensive research careers and instead seek alternative careers, outside but also within academe (for example teaching positions in Liberal Arts Schools). Recent attention to non-academic pathways has expanded our understanding of alternative PhD careers. However, career preferences and placements are also nuanced along the academic pathway. Existing research on academic careers (mostly research-centric) has found that certain factors have a significant impact on the prestige of both the institutional placement and the salary of PhD recipients. We understand less, however, about the functioning of career preferences and related placements outside of the top academic research institutions. Our work builds on prior studies of academic career placement to explore the impact that prestige of PhD-granting institution, advisor involvement, and cultural capital have on the extent to which STEM PhDs are placed in their preferred academic institution types. What determines whether an individual with a preference for research oriented institutions works at a Research Extensive university? Or whether an individual with a preference for teaching works at a Liberal Arts college? Using survey data from a nationally representative sample of faculty in biology, biochemistry, civil engineering and mathematics at four different Carnegie Classified institution types (Research Extensive, Research Intensive, Master’s I & II, and Liberal Arts Colleges), we examine the relative weight of different individual and institutional characteristics on institutional type placement. We find that doctoral institutional prestige plays a significant role in matching individuals with their preferred institutional type, but that advisor involvement only has an impact on those with a preference for research oriented institutions. Gender effects are also observed, particularly in the role of the advisor in affecting preferred career placement.U.S. National Science Foundation Grant # DRL-091019