Recovery programmes for endangered species can become increasingly demanding over time, but manag... more Recovery programmes for endangered species can become increasingly demanding over time, but managers may be reluctant to change ongoing actions that are believed to be assisting recovery. We used a quantitative risk assessment to choose support strategies for a reintroduced population of Mauritius olive white‐eyes Zosterops chloronothos. Facing increasing costs, managers considered changing the ongoing supplementary feeding strategy, but at the same time worried this could jeopardize the observed positive population trend. We used a feeding experiment to compare the current feeding regime and a cheaper alternative (a simple sugar/water mix). Results suggested the cheaper alternative would only marginally reduce population vital rates. We assessed the influence of these results and the associated uncertainty on population recovery and management costs using two decision‐analytic criteria, incremental cost‐effectiveness ratio and stochastic dominance. The new feeding regime was expect...
We report the concentrations of persistent organic pollutants (POPs) in seabird eggs from St. Bra... more We report the concentrations of persistent organic pollutants (POPs) in seabird eggs from St. Brandon's Atoll, a tropical island system in the western Indian Ocean. Ten eggs each of sooty terns (Onychoprion fuscatus), fairy terns (Gygis alba), and common noddies (Anous stolidus) were collected from the atoll. For a terrestrial reference, we analysed three feral chicken (Gallus gallus domesticus) eggs from the same location. Sooty tern eggs contained the highest mean concentrations of three chemical classes: ƩCHL3 (0.21 ng/g wm; wet mass), ƩPCB10 (1.5 ng/g wm), and ƩPBDE6 (1.1 ng/g wm). Fairy tern eggs contained the highest mean concentrations of HCB (0.68 ng/g wm) and ƩCHB5 (0.83 ng/g wm). The chicken eggs contained the highest mean concentrations of ƩDDT3 (2.6 ng/g wm), while common noddy eggs contained the highest mean concentrations of ƩHCH2 (0.5 ng/g wm). We surmise that the differences in chemical composition between species reflect different pollutant compositions in prey from the bird's different foraging ranges. The sooty terns foraging offshore contained higher POPs concentrations than the nearshore-foraging common noddies. Fairy tern eggs contained intermediate concentrations, commensurate with their intermediate foraging. Inter-island differences in contaminant concentrations were seen between eggs of the common noddies from St. Brandon's Atoll and Rodrigues Island, 520 km to the south-east. Concentrations of contaminants found in this study were lower than values quantified by other studies, making St. Brandon's Atoll an ideal reference site to monitor background concentrations of POPs in the tropical Indian Ocean.
Hibiscus liliiflorus, endemic to the Indian Ocean island of Rodrigues, is one of the rarest plant... more Hibiscus liliiflorus, endemic to the Indian Ocean island of Rodrigues, is one of the rarest plant species in the world; only 2 wild individuals remain. Previously, when 4 wild individuals remained, the Mauritian Wildlife Foundation (MWF) in Rodrigues propagated cuttings of them in their nursery, then planted seedlings produced in the nursery into 3 outplanted populations on the island. Our goals were to: 1) assess whether all 4 original wild genotypes are represented in the MWF nursery; 2) determine whether ex situ living collections at international botanical gardens maintain unique genotypes of H. liliiflorus; 3) assess whether nursery individuals have crossed or self-fertilized to produce seed and quantify their relative contributions to outplanted populations; and 4) provide recommendations for future conservation actions. We used a 2b-RADseq approach to produce 2,711 genome-wide single nucleotide polymorphisms (SNPs) from 98 samples. Genotype identity analysis, principal component analysis, and model-based clustering in STRUCTURE found 4 genotypes extant in Rodrigues but no unique genotypes in ex situ botanic garden collections. Only 3 genotypes are represented in the MWF nursery; the one remaining genotype is represented by an extant wild individual. Parentage analysis showed that seeds produced in the MWF nursery resulted from both self-fertilization and crossing between genotypes, a result supported by internal relatedness and hybrid index calculations. Each outplanted population is dominated by a subset of parental genotypes, and we propose actions to balance the parental contributions to outplanted populations. Our study highlights how genetic assessments of ex situ conservation projects help conserve critically endangered species.
ABSTRACT Threatened populations of birds are often restored after bottleneck events by using rein... more ABSTRACT Threatened populations of birds are often restored after bottleneck events by using reintroduction techniques. Whilst population numbers are often increased by using such measures, the long-term genetic effects of reintroductions and post-release management of the resulting populations are frequently overlooked. We identify an overall declining trend in population-wide estimates of genetic diversity over two decades since the initial recovery of the population from the most severe part of this species’ bottleneck. Additionally, by incorporating the genotypes of known founding individuals into population viability simulations, we evaluate the genetic effects of population management under various scenarios at both the metapopulation and subpopulation levels. We reveal that whilst population augmentation has led to increased genetic homogenisation among subpopulations, significant differentiation still exists. Simulations predict that even with a low level of natural dispersal leading to gene-flow this differentiation could be ameliorated. We conclude by offering a number of key recommendations relating to post-recovery management of reintroduced bird populations which support the encouragement of individual dispersal using established management techniques such as artificial nest-site provisioning.
Recovery programmes for endangered species can become increasingly demanding over time, but manag... more Recovery programmes for endangered species can become increasingly demanding over time, but managers may be reluctant to change ongoing actions that are believed to be assisting recovery. We used a quantitative risk assessment to choose support strategies for a reintroduced population of Mauritius olive white‐eyes Zosterops chloronothos. Facing increasing costs, managers considered changing the ongoing supplementary feeding strategy, but at the same time worried this could jeopardize the observed positive population trend. We used a feeding experiment to compare the current feeding regime and a cheaper alternative (a simple sugar/water mix). Results suggested the cheaper alternative would only marginally reduce population vital rates. We assessed the influence of these results and the associated uncertainty on population recovery and management costs using two decision‐analytic criteria, incremental cost‐effectiveness ratio and stochastic dominance. The new feeding regime was expect...
We report the concentrations of persistent organic pollutants (POPs) in seabird eggs from St. Bra... more We report the concentrations of persistent organic pollutants (POPs) in seabird eggs from St. Brandon's Atoll, a tropical island system in the western Indian Ocean. Ten eggs each of sooty terns (Onychoprion fuscatus), fairy terns (Gygis alba), and common noddies (Anous stolidus) were collected from the atoll. For a terrestrial reference, we analysed three feral chicken (Gallus gallus domesticus) eggs from the same location. Sooty tern eggs contained the highest mean concentrations of three chemical classes: ƩCHL3 (0.21 ng/g wm; wet mass), ƩPCB10 (1.5 ng/g wm), and ƩPBDE6 (1.1 ng/g wm). Fairy tern eggs contained the highest mean concentrations of HCB (0.68 ng/g wm) and ƩCHB5 (0.83 ng/g wm). The chicken eggs contained the highest mean concentrations of ƩDDT3 (2.6 ng/g wm), while common noddy eggs contained the highest mean concentrations of ƩHCH2 (0.5 ng/g wm). We surmise that the differences in chemical composition between species reflect different pollutant compositions in prey from the bird's different foraging ranges. The sooty terns foraging offshore contained higher POPs concentrations than the nearshore-foraging common noddies. Fairy tern eggs contained intermediate concentrations, commensurate with their intermediate foraging. Inter-island differences in contaminant concentrations were seen between eggs of the common noddies from St. Brandon's Atoll and Rodrigues Island, 520 km to the south-east. Concentrations of contaminants found in this study were lower than values quantified by other studies, making St. Brandon's Atoll an ideal reference site to monitor background concentrations of POPs in the tropical Indian Ocean.
Hibiscus liliiflorus, endemic to the Indian Ocean island of Rodrigues, is one of the rarest plant... more Hibiscus liliiflorus, endemic to the Indian Ocean island of Rodrigues, is one of the rarest plant species in the world; only 2 wild individuals remain. Previously, when 4 wild individuals remained, the Mauritian Wildlife Foundation (MWF) in Rodrigues propagated cuttings of them in their nursery, then planted seedlings produced in the nursery into 3 outplanted populations on the island. Our goals were to: 1) assess whether all 4 original wild genotypes are represented in the MWF nursery; 2) determine whether ex situ living collections at international botanical gardens maintain unique genotypes of H. liliiflorus; 3) assess whether nursery individuals have crossed or self-fertilized to produce seed and quantify their relative contributions to outplanted populations; and 4) provide recommendations for future conservation actions. We used a 2b-RADseq approach to produce 2,711 genome-wide single nucleotide polymorphisms (SNPs) from 98 samples. Genotype identity analysis, principal component analysis, and model-based clustering in STRUCTURE found 4 genotypes extant in Rodrigues but no unique genotypes in ex situ botanic garden collections. Only 3 genotypes are represented in the MWF nursery; the one remaining genotype is represented by an extant wild individual. Parentage analysis showed that seeds produced in the MWF nursery resulted from both self-fertilization and crossing between genotypes, a result supported by internal relatedness and hybrid index calculations. Each outplanted population is dominated by a subset of parental genotypes, and we propose actions to balance the parental contributions to outplanted populations. Our study highlights how genetic assessments of ex situ conservation projects help conserve critically endangered species.
ABSTRACT Threatened populations of birds are often restored after bottleneck events by using rein... more ABSTRACT Threatened populations of birds are often restored after bottleneck events by using reintroduction techniques. Whilst population numbers are often increased by using such measures, the long-term genetic effects of reintroductions and post-release management of the resulting populations are frequently overlooked. We identify an overall declining trend in population-wide estimates of genetic diversity over two decades since the initial recovery of the population from the most severe part of this species’ bottleneck. Additionally, by incorporating the genotypes of known founding individuals into population viability simulations, we evaluate the genetic effects of population management under various scenarios at both the metapopulation and subpopulation levels. We reveal that whilst population augmentation has led to increased genetic homogenisation among subpopulations, significant differentiation still exists. Simulations predict that even with a low level of natural dispersal leading to gene-flow this differentiation could be ameliorated. We conclude by offering a number of key recommendations relating to post-recovery management of reintroduced bird populations which support the encouragement of individual dispersal using established management techniques such as artificial nest-site provisioning.
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