Populations In Mississippi Research Articles

Multiphase optimization strategy to establish optimal delivery of nutrition-related services in healthcare settings: A step towards clinical trial

BackgroundMinorities living in the Southern US generally have greater incidence and prevalence of cardiometabolic diseases compared to other groups. Cardiometabolic disease prevalence and risk can be reduced by focusing on diet and lifestyle modifications. There is need for holistic and integrated care models for community-based healthcare organizations who are already working with minorities. This research aimed to select and optimize essential psychosocial and structural components to address diet behaviors among racial/ethnic minorities, and/or disadvantaged background young to middle aged adult populations in Mississippi. MethodsNutrition360 was guided by a community-academic team using a participatory approach and included a preparation and two optimization phases to examine different approaches to dietary interventions utilizing the multiphase optimization strategy. Each intervention arm included three different modalities to identify the most feasible delivery method. The intervention was conducted at a community-based, outpatient healthcare center located in Jackson, MS. Eligible participants were between 25 and 50 years old, residents of Jackson metropolitan area, at risk for cardiovascular disease-related premature mortality, and had internet access. Individuals who completed baseline surveys were randomly assigned to an intervention group and then to modality order. Co-primary outcomes were research participant burden and cost-effectiveness and secondary outcomes were attendance, and dietary measures. ResultsThirty-one, African American individuals with a mean age of 40.5 years completed baseline surveys and were randomized to an intervention program. ConclusionThe two most feasible and cost-effective interventions will be combined to further test this model's delivery in the real-world setting as part of the next optimization phase. RegistrationClinicalTrials.gov, NCT06286618. https://clinicaltrials.gov/study/NCT06286618

Disparities and Medical Expenditure Implications in Pediatric Tele-Mental Health Services During the COVID-19 Pandemic in Mississippi.

Tele-mental health (TMH) services, including both mental and behavioral healthcare (MBH) services, emerged as a cornerstone in delivering pediatric mental healthcare during the coronavirus disease 2019 (COVID-19) pandemic, yet their utilization and effects on healthcare resource utilization (HCRU) and medical expenditures remain unclear. To bridge the gap, this study aims to investigate the association between TMH utilization and sociodemographic factors and assess its associated HCRU and medical expenditures within a pediatric population in Mississippi. Studying 1,972 insured pediatric patients who accessed outpatient MBH services at the study institution between January 2020 and June 2023, age, race, insurance type, rural residency, and household income were identified as key determinants of TMH utilization. Adjusting for sociodemographics, TMH utilization was associated with 122% more MBH-associated outpatient visits and 36% higher related medical expenditures, but 27% less overall medical expenditures. This study reveals sociodemographic disparities in pediatric TMH utilization, highlights its role in augmenting outpatient mental healthcare access, and shows its potential for cost savings. Future efforts should aim at fostering more digitally inclusive, equitable, and affordable pediatric mental healthcare services.

Genetic diversity and population structure of a rare flowering tree endemic to Appalachia, Stewartia ovata.

Stewartia ovata (cav.) Weatherby, commonly known as mountain stewartia, is an understory tree native to the southeastern United States (U.S.). This relatively rare species occurs in isolated populations in Virginia, Kentucky, Tennessee, North Carolina, South Carolina, Georgia, Alabama, and Mississippi. As a species, S. ovata has largely been overlooked, and limited information is available regarding its ecology, which presents obstacles to conservation efforts. Stewartia ovata has vibrant, large white flowers that bloom in summer with a variety of filament colors, suggesting potential horticultural traits prized by ornamental industry. However, S. ovata is relatively slow growing and, due to long seed dormancy, propagation is challenging with limited success rates. This has created a need to assess the present genetic diversity in S. ovata populations to inform potential conservation and restoration of the species. Here, we employ a genotyping-by-sequencing (GBS) approach to characterize the spatial distribution and genetic diversity of S. ovata in the southern Appalachia region of the eastern United States. A total of 4475 single nucleotide polymorphisms (SNPs) were identified across 147 individuals from 11 collection sites. Our results indicate low genetic diversity (He = 0.216), the presence of population structure (K = 2), limited differentiation (F ST = 0.039), and high gene flow (Nm = 6.16) between our subpopulations. Principal component analysis corroborated the findings of STRUCTURE, confirming the presence of two distinct S. ovata subpopulations. One subpopulation mainly contains genotypes from the Cumberland Plateau, Tennessee, while the other consists of genotypes present in the Great Smoky Mountain ranges in Tennessee, North Carolina, and portions of Nantahala, Chattahoochee-Oconee national forests in Georgia, highlighting that elevation likely plays a major role in its distribution. Our results further suggested low inbreeding coefficient (F IS = 0.070), which is expected with an outcrossing tree species. This research further provides necessary insight into extant subpopulations and has generated valuable resources needed for conservation efforts of S. ovata.

Insecticide Susceptibilities and Enzyme Activities of Four Stink Bug Populations in Mississippi, USA.

In Mississippi, the Pentatomidae complex infesting soybean is primarily composed of Euschistus servus, Nezara viridula, Chinavia hilaris, and Piezodorus guildinii. This study employed spray bioassays to evaluate the susceptibilities of these stink bugs to seven commonly used formulated insecticides: oxamyl, acephate, bifenthrin, λ-cyhalothrin, imidacloprid, thiamethoxam, and sulfoxaflor. Stinks bugs were collected from soybeans in Leland, MS, USA during 2022 and 2023, as well as from wild host plants in Clarksdale, MS. There was no significant difference in the susceptibility of C. hilaris to seven insecticides between two years, whereas P. guildinii showed slightly increased susceptibility to neonicotinoids in 2023. Among all four stink bug species, susceptibility in 2022 was ranked as P. guildinii ≤ C. hilaris ≈ N. viridula, while in 2023, it was ranked as P. guildinii ≤ C. hilaris ≤ E. Servus. Additionally, populations of E. servus and P. guildinii collected from Clarksdale exhibited high tolerance to pyrethroids and neonicotinoids. Moreover, populations of E. servus and P. guildinii from SIMRU-2022 and Clarksdale-2023 showed elevated esterase and cytochrome P450 activity, respectively. These findings from spray bioassays and enzyme activity analyses provide a baseline for monitoring insecticide resistance in Pentatomidae and can guide insecticide resistance management strategies for Mississippi soybean.

Confirmation and differential metabolism associated with quinclorac resistance in smooth crabgrass (Digitaria ischaemum)

AbstractQuinclorac controls crabgrass (Digitaria spp.) in cool- and warm-season turfgrass species. Herbicide-resistant smooth crabgrass [Digitaria ischaemum (Schreb.) Schreb. ex Muhl.] biotypes have evolved due to recurrent usage of quinclorac. Two Mississippi populations (MSU1 and MSU2) of D. ischaemum were characterized using standard greenhouse dose–response screens to assess their resistance relative to known susceptible populations. Subsequent investigations explored mechanisms of resistance, including examining cyanide accumulation, glutathione S-transferase (GST) activity, and the potential involvement of cytochrome P450s in MSU1, MSU2, and a susceptible (SMT2). Resistant populations MSU1 and MSU2 required 80 and 5 times more quinclorac, respectively, to reach 50% biomass reduction than susceptible populations. The SMT2 biotype accumulated three times more cyanide than the resistant MSU1 and MSU2 populations. GST activity was elevated in resistant MSU1 and MSU2 populations. Furthermore, quinclorac concentrations in treated resistant populations were elevated when plants were pretreated with the P450 inhibitor malathion. These findings suggest a non–target site based mechanism of resistance involving the accumulation of cyanide. This may provide a scientific basis for understanding the occurrence of quinclorac-resistant D. ischaemum, although further research is needed to investigate potential target-site mechanisms of resistance.

INTERSECTION OF RACE AND PLACE-BASED DISPARITIES AMONG 65+ IN MISSISSIPPI

Abstract Disparities in healthy aging have been attributed to race, gender, SES, and zipcode. The Mississippi Healthy Aging Data Report (HADR) is a new resource in the state to advance age-friendly progress reporting 150 indicators related to healthy aging for 82 counties. The present study explored how race and place may be associated with community health outcomes. The main data sources include the American Community Survey, the Behavioral Risk Factor Surveillance System, and the Centers for Medicare and Medicaid Services. Bivariate statistical analyses and mapping were conducted to compare the 65+ population in Mississippi living in rural (N=65) and urban areas (N=17); counties with high (N=44) and low (N=38) proportions of 65+ black residents; and high and low black populations by rural (high: N= 38; low: N=27) and urban counties (high: N=6; low: N=11). Bivariate analyses found that the rural counties with high proportions of 65+ black residents reported consistently worse rates for 26 out of 28 indicators of healthy aging. ArcGIS Mapping demonstrated that the Mississippi rural, black population tended to be centralized to the Delta region, a historically impoverished area. This population reported the highest rates of chronic conditions and poverty, lowest rates of education and life expectancy, and the lowest access to primary care providers and hospitals. This study underscores the importance of data tools like HADR to improve healthy aging for everyone. Understanding the distribution of community rates makes disparities evident and may help practitioners and policymakers to allocate resources to areas of highest need.

Discovery and Analyses of Caulimovirid-like Sequences in Upland Cotton (Gossypium hirsutum).

Analyses of Illumina-based high-throughput sequencing data generated during characterization of the cotton leafroll dwarf virus population in Mississippi (2020-2022) consistently yielded contigs varying in size (most frequently from 4 to 7 kb) with identical nucleotide content and sharing similarities with reverse transcriptases (RTases) encoded by extant plant pararetroviruses (family Caulimoviridiae). Initial data prompted an in-depth study involving molecular and bioinformatic approaches to characterize the nature and origins of these caulimovirid-like sequences. As a result, here, we report on endogenous viral elements (EVEs) related to extant members of the family Caulimoviridae, integrated into a genome of upland cotton (Gossypium hirsutum), for which we propose the provisional name "endogenous cotton pararetroviral elements" (eCPRVE). Our investigations pinpointed a ~15 kbp-long locus on the A04 chromosome consisting of head-to-head orientated tandem copies located on positive- and negative-sense DNA strands (eCPRVE+ and eCPRVE-). Sequences of the eCPRVE+ comprised nearly complete and slightly decayed genome information, including ORFs coding for the viral movement protein (MP), coat protein (CP), RTase, and transactivator/viroplasm protein (TA). Phylogenetic analyses of major viral proteins suggest that the eCPRVE+ may have been initially derived from a genome of a cognate virus belonging to a putative new genus within the family. Unexpectedly, an identical 15 kb-long locus composed of two eCPRVE copies was also detected in a newly recognized species G. ekmanianum, shedding some light on the relatively recent evolution within the cotton family.

Characterization of 21 microsatellite loci for the precocious, grass-shrimp trematode Alloglossidium renale

We developed microsatellite markers to use in studying the population genetics of the trematode Alloglossidium renale, a fluke with a precocious life cycle where sexual maturation occurs in a grass shrimp. Among 21 tested loci in a Mississippi population sample, 14 were polymorphic, 12 of which significantly deviated from Hardy-Weinberg Equilibrium (HWE). We estimated identity disequilibrium (ID) to confirm whether the deviations from HWE were due to significant amounts of selfing or due to technical factors. The selfing rate derived from FIS was 86.6%, whereas the selfing rate obtained by ID was 83.9%, indicating that the deviation in HWE was due to a high amount of selfing within the population. These markers will be useful for ecological and evolutionary studies of A. renale especially in relation to the interplay of hermaphroditic mating systems, inbreeding depression, and transmission dynamics.

Prevalence of maxillary and mandibular exostosis in the Mississippi population: a retrospective study

Prevalence of maxillary and mandibular exostosis in the Mississippi population: a retrospective study

Trust and Biomedical Research Engagement of Minority and Under-Represented Communities in Mississippi, USA.

Trust is critical to the development and maintenance of effective research collaborations and community engagement. The purpose of this study was to assess the current attitudes and level of trust pertaining to health research among residents of Central Mississippi, the priority health region for the Research Centers in Minority Institutions (RCMI) Center for Health Disparities Research (RCHDR) at Jackson State University. The cross-sectional study was conducted from November 2021 to April 2022. The data were analyzed using descriptive statistics carried out by SPSS statistical software. A total of 146 participants responded to the survey. The participants were predominately African American (99%) and female (75%). Historical research studies, the researchers' qualities, and potential benefits from participation were factors affecting the level of trust in the research process. Ninety percent (n = 131) expressed that it was important to be involved in the research process, and 98.5% (n = 144) agreed that discussing the research findings with the participants was important for establishing trust in the research process. While trust in the research process does not guarantee participation, trust is a precursor for those who decide to engage in health disparities research. Key findings will be integrated into the RCHDR research agenda to foster further development and implementation of innovative community-based participatory research toward the control and/or prevention of diseases that disproportionately affect minority and under-represented populations in Mississippi.

Regional Differences in Mortality Rates and Characteristics of Decedents With Hepatitis B Listed as a Cause of Death, United States, 2000-2019

US hepatitis B mortality has been described nationally, but examination subnationally may identify differences in mortality rates and decedent characteristics, including birthplace. To examine characteristics of decedents with hepatitis B-listed deaths during 2010 to 2019 and compare age-adjusted hepatitis B-listed death rates during 2010 to 2019 vs 2000 to 2009. This cross-sectional study used Multiple Cause of Death data from 50 US states and the District of Columbia (DC) from 2000 to 2019 to assess characteristics of US residents with hepatitis B listed as an underlying cause of death (UCOD) or contributing cause of death on death certificates. Data were analyzed from September 2019 to May 2022. Hepatitis B listed as underlying or contributing cause of death. Outcomes of interest were hepatitis B-listed death counts, age-adjusted rates, and characteristics of decedents during 2000 to 2019. The distribution of hepatitis B-listed deaths according to sociodemographic characteristics and UCOD among US- and non-US-born decedents were also examined. A total of 35 280 decedents with hepatitis B listed as the cause of death were identified, including 17 483 deaths during 2010 to 2019. Decedents were 63.3% US-born, and 25.8% of decedents were Asian or Pacific Islander and 46.5% of decedents were White; 28.4% of decedents were listed as having hepatitis C virus (HCV) or HIV coinfection. State-level rates significantly surpassed the overall US rate (0.47 deaths per 100 000 population) in DC (high, 1.78 deaths per 100 000 population), Hawaii, Oklahoma, California, Tennessee, West Virginia, Mississippi, Oregon, Washington, Louisiana, Kentucky, and New York (low, 0.61 deaths per 100 000 population). Median (IQR) age at hepatitis B death was significantly younger in Kentucky (54.0 [46.0-64.0] years), West Virginia (56.0 [47.0-65.0] years), Tennessee (57.0 [50.0-65.0] years), Mississippi (58.0 [50.0-65.0] years), and Ohio (59.0 [50.0-66.0] years) than the national median (60.0 [53.0-69.0] years), which itself was significantly younger than nonhepatitis B-listed deaths (77 [63.0-87.0] years; P < .001). Hepatitis B was the UCOD among approximately 30% of US- and non-US-born decedents with hepatitis B COD. Irrespective of birthplace, most decedents had liver-related UCOD. Compared with non-US-born decedents, US-born decedents more frequently had nonliver conditions listed as UCOD. Liver cancer was the predominant UCOD among non-US-born decedents (37.9% of decedents). From 2000 to 2009 compared with 2010 to 2019, the hepatitis B-listed mortality rate significantly decreased nationally (change, -18.97%) and in 14 states; significant increases were observed in West Virginia (change, 83.78%) and Kentucky (change, 69.44%). These findings suggest that US-born decedents constituted two-thirds of all hepatitis B-listed deaths and median age at death was youngest in Appalachian states. Irrespective of birthplace, most decedents had liver-related UCOD; however, US-born decedents more frequently had nonliver UCOD than non-US-born decedents. In addition to addressing liver-related complications, US-born persons with chronic infection may also require diagnosis and management of multiple comorbidities.

Determinants of Population Genetic Structure in Chamaecrista fasciculata (Michx.) Greene (Fabaceae) in the Southeastern United States

Chamaecrista fasciculata is a widely distributed, phenotypically variable species in the eastern U.S. Whereas studies have demonstrated genetic structure and local adaptation in northern areas of its distribution, there has been no comparison of genetic variability among populations at the southern extent where phenotypic variation is more complex. We characterized genetic variation at 14 microsatellite loci for populations in Mississippi and Alabama and compared this to variation in a phenotypic trait, leaf pubescence. Geographic distance, climatic variables, and elevation were evaluated as factors to explain the observed patterns of genetic diversity. A significant amount of variation (19%) resided among populations, but most variation (68%) was among individuals. Assignment of individuals into genetic groups suggests two primary clusters, but these groups are not concordant with known geographical or ecological breaks, nor phenotypic variants. Genetic structure at a regional scale can be characterized as isolation by distance, while environmental factors may play a secondary role in limiting gene flow at local scales. Mean population FST is strongly associated with allelic diversity and heterozygosity, suggesting that genetic drift influences population variation. Despite the presence of genetic and phenotypic variation in southern populations of C. fasciculata, the lack of concordant patterns between these types of variation indicate that they are not driven by the same factors. This study demonstrates how local factors differentially influence the maintenance of intraspecific variation and suggest the southern distributional range is an active area of evolution for C. fasciculata.

Hybridization and low genetic diversity in the endangered Alabama red-bellied turtle (Pseudemys alabamensis).

Pseudemys alabamensis is one of the most endangered freshwater turtle species in the United States due to its restricted geographic distribution in coastal Alabama and Mississippi. Populations of P. alabamensis are geographically isolated from one another by land and saltwater, which could act as barriers to gene flow. It is currently unknown how differentiated these populations are from one another and whether they have experienced reductions in population size. Previous work found morphological differences between Alabama and Mississippi populations, suggesting that they may be evolutionarily distinct. Other Pseudemys turtles such as P. concinna and P. floridana occur naturally within the same geographic area as P. alabamensis and are known to hybridize with each other. These more abundant species could threaten the unique genetic identity of P. alabamensis through introgression. In order to evaluate the endangered status of P. alabamensis and the level of hybridization with other species, we used mitochondrial and nuclear microsatellite markers to assess genetic variation within and among populations of P. alabamensis throughout its range and estimate admixture with co‐occurring Pseudemys species. In P. alabamensis, we found no variation in mitochondrial DNA and an excess of homozygosity in microsatellite data. Our results show genetic differentiation between Alabama and Mississippi populations of P. alabamensis, and low estimated breeding sizes and signs of inbreeding for two populations (Fowl River, Alabama and Biloxi, Mississippi). We also found evidence of admixture between P. alabamensis and P. concinna/P. floridana. Based on our results, P. alabamensis is highly endangered throughout its range and threatened by both low population sizes and hybridization. In order to improve the species’ chances of survival, focus should be placed on habitat preservation, maintenance of genetic diversity within both the Mississippi and Alabama populations, and routine population‐monitoring activities such as nest surveillance and estimates of recruitment.

Incipient speciation between host-plant strains in the fall armyworm

BackgroundRecent advancement in speciation biology proposes that genetic differentiation across the whole genome (genomic differentiation, GD) may occur at the beginning of a speciation process and that GD itself may accelerate the rate of speciation. The fall armyworm (FAW, Spodoptera frugiperda) has been used as a model species to study the process of speciation between diverging host-plant strains. We showed in a previous study that GD between the host-plant strains occurred at the beginning of a speciation process based on a population genomics analysis from a population in Mississippi (USA), providing empirical support for the theoretical prediction. In a recent paper, however, panmixia was reported in FAW based on the genomic analysis of 55 individuals collected from Argentina, Brazil, Kenya, Puerto Rico, and the mainland USA. If panmixia is true, the observed differentiation in Mississippi could be at most a phenomenon specific to a geographic population, rather than a status during a speciation process. In this report, we reanalyzed the resequencing data to test the existence of population structure according to host plants using different bioinformatics pipelines.ResultsPrincipal component analysis, FST statistics, and ancestry coefficient analysis supported genetic differentiation between strains regardless of the used bioinformatics pipelines. The strain-specific selective sweep was observed from the Z chromosome, implying the presence of strain-specific divergence selection. Z chromosome has a particularly high level of genetic differentiation between strains, while autosomes have low but significant genetic differentiation. Intriguingly, the re-sequencing dataset demonstrates the spread of Bacillus thuringiensis resistance mutations from Puerto Rico to the US mainland.ConclusionsThese results show that a pair of host-plant strains in FAW experience genomic differentiation at the beginning of a speciation process, including Z chromosome divergent selection and possibly hitchhiking effect on autosomal sequences.

Macrogeographic variation of a pond predator's top‐down effects in a common garden environment

AbstractGeographic variation in species behavior and life history has been well documented in biology. Species with wide geographic distributions (i.e., across a continent) but small home ranges (i.e., &lt;1 km2) likely experience wide variability in abiotic environments across the entirety of their range, possibly exhibiting strong local adaptation. Understanding variation across a large geographic scale is especially important when considering species that have strong ecological importance, such as keystone species. Yet, few studies have compared the potential cascading ecological effects of a predator with a keystone role in at least part of its range. To understand how keystone ability in pond food webs can vary across a large geographic range, we conducted an artificial pond experiment with a known keystone predator in at least part of its range, the marbled salamander (Ambystoma opacum). To do so, we collected size‐matched salamander larvae from three geographically distant populations (&gt;650 km apart) in Ohio, Mississippi, and North Carolina and placed them in mesocosms with a suite of spring breeding amphibian prey species. We observed differential survival of some prey species leading to differences in spring‐breeding amphibian diversity among the three predator populations, indicating that keystone predation may vary at a geographic scale. Prey diversity was lowest with predators from northern (Ohio) populations of salamanders. Further understanding of large‐scale variability in ecologically important predators and the potential effects of translocating wide‐ranging ambystomatid species is needed to direct future conservation efforts and preserve biodiversity.

Geographic Distribution of the Compact Carpenter Ant Camponotus planatus (Hymenoptera: Formicidae), a Neotropical Species Spreading in Florida

Camponotus planatus Roger (Hymenoptera: Formicidae) is a broadly distributed New World carpenter ant. Here, I document the geographic distribution of C. planatus and consider evidence concerning where this species may be native, particularly whether it is native to Florida. To evaluate the distribution of C. planatus, I compiled and mapped specimen records from >1500 sites. Although, C. planatus was originally described from Cuba, it remains uncertain whether it is native or exotic there. In addition to scattered records across tropical South America, C. planatus shows a largely continuous continental distribution from Panama through Central America and Mexico to southeastern Texas. Across this continental range, C. planatus shows notable color variation, suggesting that it is native to this region. In Texas, C. planatus records dating to before 1980 are spread across most of its known range. However, eight of the nine northernmost records date to 2014 or later, including all six records from the Houston area in East Texas. This pattern suggests that C. planatus is native to Texas, but populations there appear to have recently expanded, perhaps due to climate change. Camponotus planatus populations in Florida, the Bahamas, and Mississippi are probably non-native. In Florida, C. planatus was first found in Key West in 1887, but populations appear to have greatly expanded, particularly since 1980, and now extend as far north as Jacksonville. Due to continued climate change, C. planatus may soon be able to extend its range all along the Gulf coast from Texas to Florida.

Mass Mortality of the Eastern Oyster Crassostrea virginica in the Western Mississippi Sound Following Unprecedented Mississippi River Flooding in 2019

Globally, precipitation is expected to increase along with the rise of temperatures due to climate change, increasing the likelihood of freshwater intrusion into coastal ecosystems. In the spring and summer of 2019, heavy rainfall and snowmelt in the midwestern United States caused historic flooding of the Mississippi River, warranting two openings of the Bonnet Carré Spillway (BCS) to reduce pressure on levees in New Orleans, LA. These openings released an unprecedented volume of freshwater into Lake Pontchartrain and subsequently into the Mississippi Sound. This study investigated the impacts of these freshwater releases on populations of the eastern oyster Crassostrea virginica and water quality in the western Mississippi Sound and the Bay of St. Louis. Platforms housing oysters and water quality sensors that measured dissolved oxygen, salinity, and temperature were deployed at oyster reef sites. At each reef, native oyster populations were assessed via dredge sampling to determine oyster survival. After 13 days, deployed oysters suffered 100% mortality at all sites except the Henderson Point Reef and Kittiwake Reef, the sites farthest east of the BCS. On September 27, 2019, 62 days following the BCS closing, dredge sampling revealed no live native adult oysters or spat, even at sites where living oysters were collected earlier in the summer. If BCS openings increase in frequency or duration because of elevated precipitation, oyster populations in Mississippi could remain unsustainable for harvesting unless future freshwater intrusions are incorporated into management planning.

Phenotypic Variation of Partridge Pea (Chamaecrista fasciculata) from Mississippi Persists in a Common Garden

Intraspecific phenotypic variation occurs for many different reasons and understanding its basis has applications in taxonomy, ecology, and evolution. Chamaecrista fasciculata (partridge pea) is a widely distributed species with much phenotypic variation and varied interactions with other species in communities where it grows. Botanists have often noted that phenotypic variation in some traits of this species increases from north to south in the eastern United States. In this study, we grew seeds collected from five Mississippi populations in a common greenhouse environment to determine if the observed variation in leaf and stem traits is maintained in this environment. Interpopulation variation in the greenhouse-grown plants was not as extensive as that observed under natural conditions, but significant differences were detected in the number of stems and leaves and shoot height. The number of flowers and final shoot weight of plants did not differ, suggesting that there may be multiple growth strategies for this species to achieve equal fitness. Variation was detected in stem and leaflet trichome density. The population collected at the lowest latitude showed the most distinct morphology, producing shorter plants with many branched stems, more leaves, and a higher degree of leaflet pubescence. Trait variation that has so often been observed in natural populations of this species is maintained in a common environment, suggesting a genetic basis for the observed variation. Phenotypic variation observed in this species may reflect both responses to varied selective pressures from interacting species and adaptation to differing climatic factors.

Regional replication of landscape genetics analyses of the Mississippi slimy salamander, Plethodon mississippi

Landscape genetics can identify habitat features that facilitate or resist gene flow, providing a framework for anticipating the impacts of land use changes on dispersal of individuals. To inform management, a better understanding of how inferences derived from one study region are applicable to other regions is needed. We investigated the manner in which five landscape variables correlated with gene flow among Plethodon mississippi populations in two study regions. We compared order of importance, direction (facilitation vs. resistance of gene flow) and scale of effect, and functional relationships of variables within each study area. In forests in Mississippi and Alabama, USA, we tested individual-based genetic distances derived from microsatellite genotypes against effective distances caused by agriculture, hardwoods, pine, manmade structures, and wetlands that were optimized for both scale and transformation using maximum likelihood population effects modeling. Of the landscape variables, agriculture and wetlands ranked at the top of both study areas’ models. In both forest regions, agriculture was consistently associated with resistance, whereas pine was inferred to facilitate gene flow. However, we found region-specific differences in effects of wetlands, hardwoods, and manmade structures. Configuration of the latter landscape variables differed between forest regions, which may explain the contrasting outcomes. Our results underscore the value of metareplication in revealing which components of landscape genetics models may be consistent across different portions of a species’ range, and those that have context-dependent impacts on gene flow. We also highlight the need to consider habitat configuration when interpreting the results of landscape genetics analyses.

Potential Effects of Age, Population, and Latitude on Precision of Scale and Otolith Age Estimates of White Crappie in Minnesota

Abstract We calculated between-reader precision of ages estimated with scales and whole otoliths (sagittae) of White Crappie Pomoxis annularis for 10 Minnesota populations, and determined effects of population and mean age on precision. For all samples combined, two experienced readers counted the same number of annuli on 91% of the scales and 92% of the whole otoliths. Mean coefficients of variation equaled 1.8% between scale readers and 3.0% between whole otolith readers. We detected no systematic age-bias between readers of each structure. Agreement between scale readers differed among populations, ranging from 67 to 100% among populations (median = 89%), but agreement also decreased with increasing scale age in six of these populations. Agreement between readers of whole otoliths was unaffected by increasing age of White Crappie, but agreement ranged from 39 to 100% among populations. When compared with other studies, latitude had no influence on precision of whole otolith ages because precision in the Minnesota populations differed little from precision reported for populations in Kentucky and Mississippi. Latitude could be affecting precision in scale age estimates because precision was usually better for the Minnesota populations than for populations in Oklahoma, Kentucky, and Mississippi; however, differences in viewing methods and reader competencies could also explain geographical differences.