Publications by authors named "Andrew McDougall"

8 Publications

  • Page 1 of 1

Trends in seabird breeding populations across the Great Barrier Reef.

Conserv Biol 2021 06 13;35(3):846-858. Epub 2021 Jan 13.

Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, 750 07, Sweden.

The Great Barrier Reef is an iconic ecosystem, known globally for its rich marine biodiversity that includes many thousands of tropical breeding seabirds. Despite indications of localized declines in some seabird species from as early as the mid-1990s, trends in seabird populations across the reef have never been quantified. With a long history of human impact and ongoing environmental change, seabirds are likely sentinels in this important ecosystem. Using 4 decades of monitoring data, we estimated site-specific trends for 9 seabird species from 32 islands and cays across the reef. Trends varied markedly among species and sites, but probable declines occurred at 45% of the 86 species-by-site combinations analyzed compared with increases at 14%. For 5 species, we combined site-specific trends into a multisite trend in scaled abundance, which revealed probable declines of Common Noddy (Anous stolidus), Sooty Tern (Onychoprion fuscatus), and Masked Booby (Sula dactylatra), but no long-term changes in the 2 most widely distributed species, Greater Crested Tern (Thalasseus bergii) and Brown Booby (Sula leucogaster). For Brown Booby, long-term stability largely resulted from increases at a single large colony on East Fairfax Island that offset declines at most other sites. Although growth of the Brown Booby population on East Fairfax points to the likely success of habitat restoration on the island, it also highlights a general vulnerability wherein large numbers of some species are concentrated at a small number of key sites. Identifying drivers of variation in population change across species and sites while ensuring long-term protection of key sites will be essential to securing the future of seabirds on the reef.
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http://dx.doi.org/10.1111/cobi.13630DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8336572PMC
June 2021

Age structure of the Australian lungfish (Neoceratodus forsteri).

PLoS One 2019 23;14(1):e0210168. Epub 2019 Jan 23.

Griffith University, Brisbane, QLD, Australia.

The Australian lungfish has been studied for more than a century without any knowledge of the longevity of the species. Traditional methods for ageing fish, such as analysis of otolith (ear stone) rings is complicated in that lungfish otoliths differ from teleost fish in composition. As otolith sampling is also lethal, this is not appropriate for a protected species listed under Australian legislation. Lungfish scales were removed from 500 fish from the Brisbane, Burnett and Mary rivers. A sub-sample of scales (85) were aged using bomb radiocarbon techniques and validated using scales marked previously with oxytetracycline. Lungfish ages ranged from 2.5-77 years of age. Estimated population age structures derived using an Age Length Key revealed different recruitment patterns between river systems. There were statistically significant von Bertalanffy growth model parameters estimated for each of the three rivers based on limited sample sizes. In addition, length frequency distributions between river systems were also significantly different. Further studies will be conducted to review drivers that may explain these inter-river differences.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0210168PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6343868PMC
September 2019

Monitoring age-related trends in genomic diversity of Australian lungfish.

Mol Ecol 2018 Jul 10. Epub 2018 Jul 10.

Australian Rivers Institute, Griffith University, Nathan, Qld, Australia.

An important challenge for conservation science is to detect declines in intraspecific diversity so that management action can be guided towards populations or species at risk. The lifespan of Australian lungfish (Neoceratodus forsteri) exceeds 80 years, and human impacts on breeding habitat over the last half century may have impeded recruitment, leaving populations dominated by old postreproductive individuals, potentially resulting in a small and declining breeding population. Here, we conduct a "single-sample" evaluation of genetic erosion within contemporary populations of the Australian lungfish. Genetic erosion is a temporal decline in intraspecific diversity due to factors such as reduced population size and inbreeding. We examined whether young individuals showed signs of reduced genetic diversity and/or inbreeding using a novel bomb radiocarbon dating method to age lungfish nonlethally, based on C ratios of scales. A total of 15,201 single nucleotide polymorphic (SNP) loci were genotyped in 92 individuals ranging in age from 2 to 77 years old. Standardized individual heterozygosity and individual inbreeding coefficients varied widely within and between riverine populations, but neither was associated with age, so perceived problems with recruitment have not translated into genetic erosion that could be considered a proximate threat to lungfish populations. Conservation concern has surrounded Australian lungfish for over a century. However, our results suggest that long-lived threatened species can maintain stable levels of intraspecific variability when sufficient reproductive opportunities exist over the course of a long lifespan.
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http://dx.doi.org/10.1111/mec.14791DOI Listing
July 2018

Bite count rates in free-living individuals: new insights from a portable sensor.

BMC Nutr 2018 18;4:23. Epub 2018 May 18.

Department Electrical & Computer Engineering Department, Clemson University, Clemson, SC 29634-0915 USA.

Background: Conclusions regarding bite count rates and body mass index (BMI) in free-living populations have primarily relied on self-report. The objective of this exploratory study was to compare the relationship between BMI and bite counts measured by a portable sensor called the Bite Counter in free-living populations and participants eating in residence.

Methods: Two previously conducted studies were analyzed for relationships between BMI and sensor evaluated bite count/min, and meal duration. Participants from the first study ( = 77) wore the bite counter in a free-living environment for a continuous period of 14 days. The second study ( = 214) collected bite count/min, meal duration, and total energy intake in participants who consumed one meal in a cafeteria. Linear regression was applied to examine relationships between BMI and bite count/min.

Results: There was no significant correlation in the free-living participants average bite counts per second and BMI (R = 0.03,  = 0.14) and a significant negative correlation in the cafeteria participants (  = 0.04,  = 0.03) with higher bite count rates observed in lean versus obese participants. There was a significant correlation between average meal duration and BMI in the free-living participants (  = 0.08,  = 0.01). Total energy intake in the cafeteria participants was also significantly correlated to meal duration (  = 0.31,  < 0.001).

Conclusions: With additional novel applications of the Bite Counter, insights into free-living eating behavior may provide avenues for future interventions that are sustainable for long term application.
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http://dx.doi.org/10.1186/s40795-018-0227-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7050775PMC
May 2018

Extremely low microsatellite diversity but distinct population structure in a long-lived threatened species, the Australian lungfish Neoceratodus forsteri (Dipnoi).

PLoS One 2015 8;10(4):e0121858. Epub 2015 Apr 8.

Seqwater, Ipswich, Queensland, Australia.

The Australian lungfish is a unique living representative of an ancient dipnoan lineage, listed as 'vulnerable' to extinction under Australia's Environment Protection and Biodiversity Conservation Act 1999. Historical accounts indicate this species occurred naturally in two adjacent river systems in Australia, the Burnett and Mary. Current day populations in other rivers are thought to have arisen by translocation from these source populations. Early genetic work detected very little variation and so had limited power to answer questions relevant for management including how genetic variation is partitioned within and among sub-populations. In this study, we use newly developed microsatellite markers to examine samples from the Burnett and Mary Rivers, as well as from two populations thought to be of translocated origin, Brisbane and North Pine. We test whether there is significant genetic structure among and within river drainages; assign putatively translocated populations to potential source populations; and estimate effective population sizes. Eleven polymorphic microsatellite loci genotyped in 218 individuals gave an average within-population heterozygosity of 0.39 which is low relative to other threatened taxa and for freshwater fishes in general. Based on FST values (average over loci = 0.11) and STRUCTURE analyses, we identify three distinct populations in the natural range, one in the Burnett and two distinct populations in the Mary. These analyses also support the hypothesis that the Mary River is the likely source of translocated populations in the Brisbane and North Pine rivers, which agrees with historical published records of a translocation event giving rise to these populations. We were unable to obtain bounded estimates of effective population size, as we have too few genotype combinations, although point estimates were low, ranging from 29 - 129. We recommend that, in order to preserve any local adaptation in the three distinct populations that they be managed separately.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0121858PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4390199PMC
April 2016

Relationships between body roundness with body fat and visceral adipose tissue emerging from a new geometrical model.

Obesity (Silver Spring) 2013 Nov 11;21(11):2264-71. Epub 2013 Jun 11.

Center for Quantitative Obesity Research, Montclair State University, Montclair, NJ, USA.

Objective: To develop a new geometrical index that combines height, waist circumference (WC), and hip circumference (HC) and relate this index to total and visceral body fat.

Design And Methods: Subject data were pooled from three databases that contained demographic, anthropometric, dual energy X-ray absorptiometry (DXA) measured fat mass, and magnetic resonance imaging measured visceral adipose tissue (VAT) volume. Two elliptical models of the human body were developed. Body roundness was calculated from the model using a well-established constant arising from the theory. Regression models based on eccentricity and other variables were used to predict %body fat and %VAT.

Results: A body roundness index (BRI) was derived to quantify the individual body shape in a height-independent manner. Body roundness slightly improved predictions of %body fat and %VAT compared to the traditional metrics of body mass index (BMI), WC, or HC. On this basis, healthy body roundness ranges were established. An automated graphical program simulating study results was placed at http://www.pbrc.edu/bodyroundness.

Conclusion: BRI, a new shape measure, is a predictor of %body fat and %VAT and can be applied as a visual tool for health status evaluations.
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http://dx.doi.org/10.1002/oby.20408DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3692604PMC
November 2013

New fat free mass - fat mass model for use in physiological energy balance equations.

Nutr Metab (Lond) 2010 May 9;7:39. Epub 2010 May 9.

Department of Mathematical Sciences, Montclair State University, Montclair, NJ, USA.

Background: The Forbes equation relating fat-free mass (FFM) to fat mass (FM) has been used to predict longitudinal changes in FFM during weight change but has important limitations when paired with a one dimensional energy balance differential equation. Direct use of the Forbes model within a one dimensional energy balance differential equation requires calibration of a translate parameter for the specific population under study. Comparison of translates to a representative sample of the US population indicate that this parameter is a reflection of age, height, race and gender effects.

Results: We developed a class of fourth order polynomial equations relating FFM to FM that consider age, height, race and gender as covariates eliminating the need to calibrate a parameter to baseline subject data while providing meaningful individual estimates of FFM. Moreover, the intercepts of these polynomial equations are nonnegative and are consistent with observations of very low FM measured during a severe Somali famine. The models preserve the predictive power of the Forbes model for changes in body composition when compared to results from several longitudinal weight change studies.

Conclusions: The newly developed FFM-FM models provide new opportunities to compare individuals undergoing weight change to subjects in energy balance, analyze body composition for individual parameters, and predict body composition during weight change when pairing with energy balance differential equations.
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http://dx.doi.org/10.1186/1743-7075-7-39DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2879256PMC
May 2010

Violence-related behaviors among Dominican adolescents: examining the influence of alcohol and marijuana use.

J Ethn Subst Abuse 2008 ;7(4):404-27

Department of Family and Child Studies, College of Education and Human Servises, Montclair State University, Montclair, NJ 07043, USA.

This study identified the predictors of youth violence and violent victimization among a sample of Dominican adolescents (N=155) attending high school in a northeastern urban community. As part of a broader community-based needs assessment, students participated in an evaluation of a substance abuse prevention program funded by the Substance Abuse and Mental Health Services Administration. Correlations, principal components, multiple imputation, and stepwise regression analyses were systematically employed to develop a parsimonious model for predicting violence-related behaviors among Dominican youth. Findings suggest that early onset of alcohol and marijuana use was associated with an increased likelihood of engaging in violence-related behaviors or being the victim of a violent act. In addition, students who reported a lowered sense of safety were more likely to be involved in acts of violence. However, adolescents who reported depressive symptoms were less inclined to become involved in violence-related behaviors. Implications for culturally-tailored violence and substance abuse prevention programming efforts are discussed.
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http://dx.doi.org/10.1080/15332640802508028DOI Listing
March 2009
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