reintroduced population
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2021 ◽  
Author(s):  
◽  
Kimberly Anne Miller

<p>As habitat loss, introduced predators, and disease epidemics threaten species worldwide, translocation provides one of the most powerful tools for species conservation. However, reintroduced populations of threatened species are often founded by a small number of individuals (typically 30 in New Zealand) and generally have low success rates. The loss of genetic diversity combined with inbreeding depression in a small reintroduced population could reduce the probability of establishment and persistence. Effective management of genetic diversity is therefore central to the success of reintroduced populations in both the short- and long-term. Using population modelling and empirical data from source and reintroduced populations of skinks and tuatara, I examined factors that influence inbreeding dynamics and the long-term maintenance of genetic diversity in translocated populations. The translocation of gravid females aided in increasing the effective population size after reintroduction. Models showed that supplementation of reintroduced populations reduced the loss of heterozygosity over 10 generations in species with low reproductive output, but not for species with higher output. Harvesting from a reintroduced population for a second-order translocation accelerated the loss of heterozygosity in species with low intrinsic rates of population growth. Male reproductive skew also accelerated the loss of genetic diversity over 10 generations, but the effect was only significant when the population size was small. Further, when populations at opposite ends of a species' historic range are disproportionately vulnerable to extinction and background inbreeding is high, genetic differentiation among populations may be an artefact of an historic genetic gradient coupled with rapid genetic drift. In these situations, marked genetic differences should not preclude hybridising populations to mitigate the risks of inbreeding after reintroduction. These results improve translocation planning for many species by offering guidelines for maximising genetic diversity in founder groups and managing populations to improve the long-term maintenance of diversity. For example, founder groups should be larger than 30 for  reintroductions of species with low reproductive output, high mortality rates after release, highly polygynous mating systems, and high levels of background inbreeding. This study also provides a basis for the development of more complex models of losses of genetic diversity after translocation and how genetic drift may affect the long-term persistence of these valuable  populations.</p>


2021 ◽  
Author(s):  
◽  
Kimberly Anne Miller

<p>As habitat loss, introduced predators, and disease epidemics threaten species worldwide, translocation provides one of the most powerful tools for species conservation. However, reintroduced populations of threatened species are often founded by a small number of individuals (typically 30 in New Zealand) and generally have low success rates. The loss of genetic diversity combined with inbreeding depression in a small reintroduced population could reduce the probability of establishment and persistence. Effective management of genetic diversity is therefore central to the success of reintroduced populations in both the short- and long-term. Using population modelling and empirical data from source and reintroduced populations of skinks and tuatara, I examined factors that influence inbreeding dynamics and the long-term maintenance of genetic diversity in translocated populations. The translocation of gravid females aided in increasing the effective population size after reintroduction. Models showed that supplementation of reintroduced populations reduced the loss of heterozygosity over 10 generations in species with low reproductive output, but not for species with higher output. Harvesting from a reintroduced population for a second-order translocation accelerated the loss of heterozygosity in species with low intrinsic rates of population growth. Male reproductive skew also accelerated the loss of genetic diversity over 10 generations, but the effect was only significant when the population size was small. Further, when populations at opposite ends of a species' historic range are disproportionately vulnerable to extinction and background inbreeding is high, genetic differentiation among populations may be an artefact of an historic genetic gradient coupled with rapid genetic drift. In these situations, marked genetic differences should not preclude hybridising populations to mitigate the risks of inbreeding after reintroduction. These results improve translocation planning for many species by offering guidelines for maximising genetic diversity in founder groups and managing populations to improve the long-term maintenance of diversity. For example, founder groups should be larger than 30 for  reintroductions of species with low reproductive output, high mortality rates after release, highly polygynous mating systems, and high levels of background inbreeding. This study also provides a basis for the development of more complex models of losses of genetic diversity after translocation and how genetic drift may affect the long-term persistence of these valuable  populations.</p>


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Carmen Rueda ◽  
José Jiménez ◽  
María Jesús Palacios ◽  
Antoni Margalida

AbstractIn reintroduction projects, an analysis of dispersal, exploratory movements and territorial behavior of the species concerned offers valuable information on the adaptive management of threatened species and provides a basis for the management of future reintroductions. This is the case of the Iberian lynx (Lynx pardinus) an endemic and endangered species reintroduced in Extremadura (Spain) in 2014. We analysed spatial data from 32 individuals just after their reintroduction. Our findings show exploratory movements sufficient to colonise and connect population nuclei within a radius of about 50 km of the reintroduction area. No significant differences were found in the exploratory movements capacity or in any directionality of males and females. Our results showed an effect of sex on the sizes of the territories established, as well as an inverse relationship between them and the time elapsed since release. No effects of rabbit abundance and lynx density on the size of territories are occurring during the early stages of reintroduction. On average, the territories of reintroduced individuals were less stable than those previously described in natural populations. Findings indicate that the reintroduced population has successfully been established but it takes more than 5 years to stabilize the territories in the area. Exploratory movements of reintroduced lynx can be large and in any direction, even when there is still a lot of high quality habitat available, which should be taken into account when reintroducing species, especially terrestrial carnivores.


Diversity ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 257
Author(s):  
Rujiporn Thavornkanlapachai ◽  
Harriet R. Mills ◽  
Kym Ottewell ◽  
J. Anthony Friend ◽  
W. Jason Kennington

The loss of genetic variation and genetic divergence from source populations are common problems for reintroductions that use captive animals or a small number of founders to establish a new population. This study evaluated the genetic changes occurring in a captive and a reintroduced population of the dibbler (Parantechinus apicalis) that were established from multiple source populations over a twelve-year period, using 21 microsatellite loci. While the levels of genetic variation within the captive and reintroduced populations were relatively stable, and did not differ significantly from the source populations, their effective population size reduced 10–16-fold over the duration of this study. Evidence of some loss of genetic variation in the reintroduced population coincided with genetic bottlenecks that occurred after the population had become established. Detectable changes in the genetic composition of both captive and reintroduced populations were associated with the origins of the individuals introduced to the population. We show that interbreeding between individuals from different source populations lowered the genetic relatedness among the offspring, but this was short-lived. Our study highlights the importance of sourcing founders from multiple locations in conservation breeding programs to avoid inbreeding and maximize allelic diversity. The manipulation of genetic composition in a captive or reintroduced population is possible with careful management of the origins and timings of founder releases.


2021 ◽  
Vol 13 (10) ◽  
pp. 1876
Author(s):  
Serge Yan Landau ◽  
Ido Isler ◽  
Levana Dvash ◽  
Benny Shalmon ◽  
Amir Arnon ◽  
...  

The re-introduction paradigm is that Arabian Oryx (Oryx leucoryx) herds adjust the size of their home ranges depending on the availability of vegetation, which is directly related to rainfall. In Israel, Arabian oryx were released in two hyper-arid sites: the Arava Valley and in the Paran wilderness, belonging to the Sudanese and the Saharo–Arabian biogeographic zones, respectively. While post-release survival was similar in both, reproductive success in the Paran wilderness reintroduction site was extremely low, resulting in an acute decline of the reintroduced population over time. The hypothesis that impaired nutrition might be associated with this finding was assessed with near-infrared spectroscopy (NIRS)-aided chemistry of monthly sampled fecal pellets, used as remote sensing evidence of ingested diets, throughout a year. Fecal nitrogen (FN), used as an estimate of nutritional status, was consistently higher in the Arava. Grass was never the sole or even a major dietary component. The dietary contribution of tannin-rich browse was high and steady all year-round in the Arava and increased steadily in Paran from winter to summer, corresponding to the period of availability of Acacia raddiana pods in both regions. The oryx in Paran had a home-range that was ten-fold, compared to the Arava, suggesting less feed availability. Acacia browsing may mitigate the effects of temporal variance in primary production. Under such conditions, oryx should be preferably released in areas that support significant acacia stands.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yashuai Zhang ◽  
Fang Wang ◽  
Zhenxia Cui ◽  
Min Li ◽  
Xia Li ◽  
...  

Abstract Background One of the most challenging tasks in wildlife conservation and management is clarifying which and how external and intrinsic factors influence wildlife demography and long-term viability. The wild population of the Crested Ibis (Nipponia nippon) has recovered to approximately 4400, and several reintroduction programs have been carried out in China, Japan and Korea. Population viability analysis on this endangered species has been limited to the wild population, showing that the long-term population growth is restricted by the carrying capacity and inbreeding. However, gaps in knowledge of the viability of the reintroduced population and its drivers in the release environment impede the identification of the most effective population-level priorities for aiding in species recovery. Methods The field monitoring data were collected from a reintroduced Crested Ibis population in Ningshan, China from 2007 to 2018. An individual-based VORTEX model (Version 10.3.5.0) was used to predict the future viability of the reintroduced population by incorporating adaptive patterns of ibis movement in relation to catastrophe frequency, mortality and sex ratio. Results The reintroduced population in Ningshan County is unlikely to go extinct in the next 50 years. The population size was estimated to be 367, and the population genetic diversity was estimated to be 0.97. Sensitivity analysis showed that population size and extinction probability were dependent on the carrying capacity and sex ratio. The carrying capacity is the main factor accounting for the population size and genetic diversity, while the sex ratio is the primary factor responsible for the population growth trend. Conclusions A viable population of the Crested Ibis can be established according to population viability analysis. Based on our results, conservation management should prioritize a balanced sex ratio, high-quality habitat and low mortality.


2021 ◽  
Author(s):  
Róisín Campbell‐Palmer ◽  
Frank Rosell ◽  
Adam Naylor ◽  
Georgina Cole ◽  
Stephanie Mota ◽  
...  

2021 ◽  
pp. 55-59
Author(s):  
Josh Dawson

Photographic identification of individual animals is a non-invasive and cost-effective method that can provide demographic information on wild populations. This study aims to compare two photo-matching algorithms (Wild- ID and I3S-Spot) using a reintroduced population of pool frogs (Pelophylax lessonae) in the UK as a case study. We compared the following parameters 1) sex and age, 2) image quality, 3) image collection size and 4) processing time to evaluate successful image match rates. There were no significant differences in successful match rates found between sex and age groups. Wild-ID was more sensitive to image quality than I3S-Spot. There was a significant negative relationship between image collection size and successful match rates for I3S-Spot, however, no such relationship for Wild-ID. The findings of our study can be used by conservation practitioners to reduce workload and improve accuracy during population monitoring activities.


2020 ◽  
pp. 1-10
Author(s):  
MIN LI ◽  
XINPING YE ◽  
RONG DONG ◽  
XUEJING ZHANG ◽  
HU ZHANG ◽  
...  

Summary Reintroductions aim to re-establish a viable population within the indigenous range of living organisms, especially of threatened species. The population of the Asian Crested Ibis Nipponia nippon, a well-known ‘Endangered’ bird species, has increased over 100 times since wild populations were rediscovered in 1981, and several reintroduction projects were subsequently carried out in its former range. An experimental release of the Asian Crested Ibis was conducted in Qianhu National Wetland Park located in the southern part of the Loess Plateau, China. It is vitally important to monitor released birds (at least their survival and breeding), to inform subsequent releases in other suitable sites. During extensive post-release monitoring, data on capture-recapture and reproductive status were obtained using banding, radiotelemetry, and field observations. Using the Cormack-Jolly-Seber (C-J-S) model, the average annual survival rates were estimated to be 0.569 (95% CI: 0.353–0.762) for released individuals and 0.643 (95% CI: 0.038–0.987) for all individuals. From 2014 to 2018, a total of 14 breeding pairs produced 28 eggs and 10 fledglings with successful reproduction of the second generation. The mean clutch size was 2.07 ± 0.25 (n = 29), and the breeding success was 34.5%. Predation and poor habitat quality have been shown to be the main factors affecting the reintroduced population at establishment stage. Some management suggestions at the metapopulation and ecosystem levels, including further release, predator control and habitat improvement, have been proposed.


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