Background:Conservation of small and isolated populations can be challenging since they are prone to loss of genetic diversity due to random genetic drift and inbreeding.Therefore,information from the assessment of ge...Background:Conservation of small and isolated populations can be challenging since they are prone to loss of genetic diversity due to random genetic drift and inbreeding.Therefore,information from the assessment of genetic diversity and structure are needed for conservation programs to determine the appropriate management strategy for the populations.We investigated the levels of genetic variability in a resident Greylag Goose(Anser anser) population,the southernmost breeding population of the species in Europe and the sole viable population of any goose species in Greece.Methods:A fragment of mtDNA Control Region and a panel of 11 microsatellite markers were used to search for any signs of genetic impoverishment and population substructure and to reveal the underlying processes through the identification of possible past demographic events.Results:The population was found to be monomorphic in the amplified fragment of the mitochondrial Control Region,with all individuals sharing a single private haplotype.Analyses showed a lack of any population substructure indicating a panmictic population.Although the population seems to have experienced a strong and recent genetic bottleneck and exhibits a small effective population size,we did not find evidence of either extremely low levels of genetic diversity or inbreeding depression.Conclusions:The recent demographic decline we detected and the combined influence of residency and anthropogenic factors have probably shaped the current genetic status.Our study population does not need emergency conservation actions but should be regarded as a discrete management unit.Future management strategies should focus on population and genetic monitoring and preventing further abundance declines that would increase the risk of genetic impoverishment.展开更多
The analysis of bird ringing data often comes with some potential sources of error and bias,as ring wear and/or loss could affect mark-recapture analyses and produce erroneous estimates of survival.Furthermore,ring we...The analysis of bird ringing data often comes with some potential sources of error and bias,as ring wear and/or loss could affect mark-recapture analyses and produce erroneous estimates of survival.Furthermore,ring wear and loss rates may differ between and within species based on the habitat they use or the species’ life-history traits and behaviour as well as the type of the ring.In this study we use resighting data from a long-term double marking experiment to directly estimate the rate of colour-ring loss among different Dalmatian Pelican colonies over time,evaluate any possible factors that could contribute to differential ring loss and assess how it may bias the results of mark-resighting analyses.Based on 14,849 resightings from 1275 individuals and using multi-state continuous-time hidden Markov models(HMMs) we showed that probability of ring loss was markedly different among colonies,ranging from 0.10 to 0.42 within the first year of marking,whereas the cumulative probability of losing a ring after ten years ranged 0.64 to 0.99.These rates are among the highest estimated when compared to previous studies in waterbirds.Our approach assessing the intra-specific variance in ring loss provided several factors potentially involved,such as the use of glue and the fledgling age accuracy and we could further hypothesise the effect of environmental factors.Finally,our results showed that ring loss can be a significant challenge for the assessment of the species’ population dynamics using mark-recapture methods as survival was consistently underestimated when not accounting for ring loss and varied significantly among different colonies.展开更多
基金supported financially by the MAVA Foundationpartly funded through a grant by the Green Fund of the Hellenic Ministry of Environment and Energy+2 种基金a grant by the Bodosaki Foundationtwo grants by two groups of Dutch naturalistsled by the biologist Gerrit Jansen("Nature Workshops Gerrit Jansen")
文摘Background:Conservation of small and isolated populations can be challenging since they are prone to loss of genetic diversity due to random genetic drift and inbreeding.Therefore,information from the assessment of genetic diversity and structure are needed for conservation programs to determine the appropriate management strategy for the populations.We investigated the levels of genetic variability in a resident Greylag Goose(Anser anser) population,the southernmost breeding population of the species in Europe and the sole viable population of any goose species in Greece.Methods:A fragment of mtDNA Control Region and a panel of 11 microsatellite markers were used to search for any signs of genetic impoverishment and population substructure and to reveal the underlying processes through the identification of possible past demographic events.Results:The population was found to be monomorphic in the amplified fragment of the mitochondrial Control Region,with all individuals sharing a single private haplotype.Analyses showed a lack of any population substructure indicating a panmictic population.Although the population seems to have experienced a strong and recent genetic bottleneck and exhibits a small effective population size,we did not find evidence of either extremely low levels of genetic diversity or inbreeding depression.Conclusions:The recent demographic decline we detected and the combined influence of residency and anthropogenic factors have probably shaped the current genetic status.Our study population does not need emergency conservation actions but should be regarded as a discrete management unit.Future management strategies should focus on population and genetic monitoring and preventing further abundance declines that would increase the risk of genetic impoverishment.
基金supported by MAVA Foundation and Tour du Valatsupported financially by the MAVA Foundationby the Prespa Ohrid Nature Trust (PONT)。
文摘The analysis of bird ringing data often comes with some potential sources of error and bias,as ring wear and/or loss could affect mark-recapture analyses and produce erroneous estimates of survival.Furthermore,ring wear and loss rates may differ between and within species based on the habitat they use or the species’ life-history traits and behaviour as well as the type of the ring.In this study we use resighting data from a long-term double marking experiment to directly estimate the rate of colour-ring loss among different Dalmatian Pelican colonies over time,evaluate any possible factors that could contribute to differential ring loss and assess how it may bias the results of mark-resighting analyses.Based on 14,849 resightings from 1275 individuals and using multi-state continuous-time hidden Markov models(HMMs) we showed that probability of ring loss was markedly different among colonies,ranging from 0.10 to 0.42 within the first year of marking,whereas the cumulative probability of losing a ring after ten years ranged 0.64 to 0.99.These rates are among the highest estimated when compared to previous studies in waterbirds.Our approach assessing the intra-specific variance in ring loss provided several factors potentially involved,such as the use of glue and the fledgling age accuracy and we could further hypothesise the effect of environmental factors.Finally,our results showed that ring loss can be a significant challenge for the assessment of the species’ population dynamics using mark-recapture methods as survival was consistently underestimated when not accounting for ring loss and varied significantly among different colonies.
