scholarly journals Extensive population decline in the Tasmanian devil predates European settlement and devil facial tumour disease

2014 ◽  
Vol 10 (11) ◽  
pp. 20140619 ◽  
Author(s):  
Anna Brüniche-Olsen ◽  
Menna E. Jones ◽  
Jeremy J. Austin ◽  
Christopher P. Burridge ◽  
Barbara R. Holland
Keyword(s):  
Genetic Diversity ◽  
Environmental Changes ◽  
Southern Oscillation ◽  
Demographic History ◽  
Population Decline ◽  
Tasmanian Devil ◽  
Term Survival ◽  
Temporal Sampling ◽  
Low Genetic Diversity ◽  
Devil Facial Tumour Disease

The Tasmanian devil ( Sarcophilus harrisii ) was widespread in Australia during the Late Pleistocene but is now endemic to the island of Tasmania. Low genetic diversity combined with the spread of devil facial tumour disease have raised concerns for the species’ long-term survival. Here, we investigate the origin of low genetic diversity by inferring the species' demographic history using temporal sampling with summary statistics, full-likelihood and approximate Bayesian computation methods. Our results show extensive population declines across Tasmania correlating with environmental changes around the last glacial maximum and following unstable climate related to increased ‘El Niño–Southern Oscillation’ activity.

scholarly journals Microsatellite analysis reveals low genetic diversity in managed populations of the critically endangered gharial (Gavialis gangeticus) in India

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Surya Prasad Sharma ◽  
Mirza Ghazanfarullah Ghazi ◽  
Suyash Katdare ◽  
Niladri Dasgupta ◽  
Samrat Mondol ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Indian Subcontinent ◽  
Population Decline ◽  
Mitochondrial Control Region ◽  
Critically Endangered ◽  
Term Survival ◽  
Low Level ◽  
Genetic Status ◽  
In The Wild ◽  
Gavialis Gangeticus

AbstractThe gharial (Gavialis gangeticus) is a critically endangered crocodylian, endemic to the Indian subcontinent. The species has experienced severe population decline during the twentieth century owing to habitat loss, poaching, and mortalities in passive fishing. Its extant populations have largely recovered through translocation programmes initiated in 1975. Understanding the genetic status of these populations is crucial for evaluating the effectiveness of the ongoing conservation efforts. This study assessed the genetic diversity, population structure, and evidence of genetic bottlenecks of the two managed populations inhabiting the Chambal and Girwa Rivers, which hold nearly 80% of the global gharial populations. We used seven polymorphic nuclear microsatellite loci and a 520 bp partial fragment of the mitochondrial control region (CR). The overall mean allelic richness (Ar) was 2.80 ± 0.40, and the observed (Ho) and expected (He) heterozygosities were 0.40 ± 0.05 and 0.39 ± 0.05, respectively. We observed low levels of genetic differentiation between populations (FST = 0.039, P < 0.05; G’ST = 0.058, P < 0.05 Jost’s D = 0.016, P < 0.05). The bottleneck analysis using the M ratio (Chambal = 0.31 ± 0.06; Girwa = 0.41 ± 0.12) suggested the presence of a genetic bottleneck in both populations. The mitochondrial CR also showed a low level of variation, with two haplotypes observed in the Girwa population. This study highlights the low level of genetic diversity in the two largest managed gharial populations in the wild. Hence, it is recommended to assess the genetic status of extant wild and captive gharial populations for planning future translocation programmes to ensure long-term survival in the wild.

scholarly journals Low major histocompatibility complex diversity in the Tasmanian devil predates European settlement and may explain susceptibility to disease epidemics

2013 ◽  
Vol 9 (1) ◽  
pp. 20120900 ◽  
Author(s):  
Katrina Morris ◽  
Jeremy J. Austin ◽  
Katherine Belov
Keyword(s):  
Major Histocompatibility Complex ◽  
Tasmanian Devil ◽  
Major Histocompatibility ◽  
European Settlement ◽  
Low Genetic Diversity ◽  
Histocompatibility Complex ◽  
Devil Facial Tumour Disease ◽  
History Of ◽  
Mhc Diversity ◽  
Disease Epidemics

The Tasmanian devil ( Sarcophilus harrisii ) is at risk of extinction owing to the emergence of a contagious cancer known as devil facial tumour disease (DFTD). The emergence and spread of DFTD has been linked to low genetic diversity in the major histocompatibility complex (MHC). We examined MHC diversity in historical and ancient devils to determine whether loss of diversity is recent or predates European settlement in Australia. Our results reveal no additional diversity in historical Tasmanian samples. Mainland devils had common modern variants plus six new variants that are highly similar to existing alleles. We conclude that low MHC diversity has been a feature of devil populations since at least the Mid-Holocene and could explain their tumultuous history of population crashes.

Nuclear and cytoplasmic genetic diversity reveals long-term population decline in Abies semenovii, an endemic fir of central Asia

2012 ◽  
Vol 42 (12) ◽  
pp. 2142-2152 ◽  
Author(s):  
Svetlana A. Semerikova ◽  
Martin Lascoux ◽  
Vladimir L. Semerikov
Keyword(s):  
Genetic Diversity ◽  
Central Asia ◽  
Population Decline ◽  
Population Expansion ◽  
Nuclear Marker ◽  
Effective Population ◽  
Species Status ◽  
Siberian Fir ◽  
Low Genetic Diversity

The genus Abies is one of the largest conifer genera and many of the marginal species remain poorly characterized. Abies semenovii B. Fedtsch. is a rare mountain fir species from central Asia, and its species status is still disputed. We used both nuclear (allozymes and AFLP) and chloroplastic (cpSSR) markers to show that A. semenovii deserves to be considered as a species and that its low genetic diversity justifies more a proactive conservation policy. First, A. semenovii was significantly differentiated from the Siberian fir Abies sibirica Ledeb. and we did not detect gene flow between the two species. Second, A. semenovii has a very low nuclear genetic diversity, suggesting a prolonged restricted effective population size. Abies semenovii had low cpSSR diversity too but the identification of seven closely related haplotypes suggests that these mutations accumulated recently during a phase of population expansion. This agrees well with the palynological record and is in contrast with the situation observed in another rare Eurasian fir endemic to Kamchatka, Abies gracilis Kom., which was devoid of variation in cpSSRs but that also had a more substantial nuclear marker diversity than A. semenovii, thereby suggesting a more recent but less severe population bottleneck.

Are any populations 'safe'? Unexpected reproductive decline in a population of Tasmanian devils free of devil facial tumour disease

2018 ◽  
Vol 45 (1) ◽  
pp. 31 ◽  
Author(s):  
K. A. Farquharson ◽  
R. M. Gooley ◽  
S. Fox ◽  
S. J. Huxtable ◽  
K. Belov ◽  
...  
Keyword(s):  
Conservation Management ◽  
Southern Oscillation ◽  
Demographic Data ◽  
Management Strategies ◽  
Natural Populations ◽  
Significant Decline ◽  
Tasmanian Devil ◽  
Devil Facial Tumour Disease ◽  
In The Wild ◽  
Reproductive Rates

Context Conservation management relies on baseline demographic data of natural populations. For Tasmanian devils (Sarcophilus harrisii), threatened in the wild by two fatal and transmissible cancers (devil facial tumour disease DFTD: DFT1 and DFT2), understanding the characteristics of healthy populations is crucial for developing adaptive management strategies to bolster populations in the wild. Aims Our analysis aims to evaluate contemporary reproductive rates for wild, DFTD-free Tasmanian devil populations, and to provide a baseline with which to compare the outcome of current translocation activities. Methods We analysed 8 years of field-trapping data, including demographics and reproductive rates, across 2004–16, from the largest known DFTD-free remnant population at Woolnorth, Tasmania. Key results Surprisingly, we found a dramatic and statistically significant decline in female breeding rate when comparing data collected from 2004–2009 with data from 2014–2016. Unfortunately we do not have any data from the intermediate years. This decline in breeding rate was accompanied by a subtle but statistically significant decline in litter sizes. These changes were not associated with a change in body condition over the same period. Furthermore, we could not attribute the decline in breeding to a change in population size or sex ratio. Preliminary analysis suggested a possible association between annual breeding rate and coarse measures of environmental variation (Southern Oscillation Index), but any mechanistic associations are yet to be determined. Conclusions The decline in breeding rates was unexpected, so further monitoring and investigation into potential environmental and/or biological reasons for the decline in breeding rate are recommended before the arrival of DFTD at Woolnorth. Implications Our results provide valuable data to support the conservation management of Tasmanian devils in their native range. They also highlight the importance of continued monitoring of ‘safe’ populations, in the face of significant threats elsewhere.

Long-term survival despite low genetic diversity in the critically endangered Madagascar fish-eagle

2008 ◽  
Author(s):  
JEFF A. JOHNSON ◽  
RUTH E. TINGAY ◽  
MELANIE CULVER ◽  
FRANK HAILER ◽  
MICHÈLE L. CLARKE ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Critically Endangered ◽  
Term Survival ◽  
Long Term Survival ◽  
Low Genetic Diversity

scholarly journals Low Genetic Diversity in Wide-Spread Eurasian Liver Fluke Opisthorchis felineus Suggests Special Demographic History of This Trematode Species

PLoS ONE ◽  
2013 ◽  
Vol 8 (4) ◽  
pp. e62453 ◽  
Author(s):  
Ilja I. Brusentsov ◽  
Alexey V. Katokhin ◽  
Irina V. Brusentsova ◽  
Sergei V. Shekhovtsov ◽  
Sergei N. Borovikov ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Liver Fluke ◽  
Demographic History ◽  
Trematode Species ◽  
Wide Spread ◽  
Opisthorchis Felineus ◽  
Low Genetic Diversity ◽  
History Of

Population dynamics of the liver fluke, Fasciola hepatica: the effect of time and spatial separation on the genetic diversity of fluke populations in the Netherlands

Parasitology ◽  
2010 ◽  
Vol 138 (2) ◽  
pp. 215-223 ◽  
Author(s):  
S. M. WALKER ◽  
C. JOHNSTON ◽  
E. M. HOEY ◽  
I. FAIRWEATHER ◽  
F. BORGSTEEDE ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
The Netherlands ◽  
Liver Fluke ◽  
Environmental Changes ◽  
Fasciola Hepatica ◽  
Spatial Separation ◽  
Context Analysis ◽  
Temporal Sampling ◽  
The Stability

SUMMARYAn evaluation of the genetic diversity within Fasciola hepatica (liver fluke) may provide an insight into its potential to respond to environmental changes, such as anthelmintic use or climate change. In this study, we determined the mitochondrial DNA haplotypes of >400 flukes from 29 individual cattle, from 2 farms in the Netherlands, as an exemplar of fasciolosis in a European context. Analysis of this dataset has provided us with a measure of the genetic variation within infrapopulations (individual hosts) and the diversity between infrapopulations within a herd of cattle. Temporal sampling from one farm allowed for the measurement of the stability of genetic variation at a single location, whilst the comparison between the two farms provided information on the variation in relation to distance and previous anthelmintic regimes. We showed that the liver fluke population in this region is predominantly linked to 2 distinct clades. Individual infrapopulations contain a leptokurtic distribution of genetically diverse flukes. The haplotypes present on a farm have been shown to change significantly over a relatively short time-period.

scholarly journals How much genetic variation is stored in the endangered and fragmented shrub Tetraena mongolica Maxim?

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5645 ◽  
Author(s):  
Yingbiao Zhi ◽  
Zhonglou Sun ◽  
Ping Sun ◽  
Kai Zhao ◽  
Yangnan Guo ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Background ◽  
Yellow River ◽  
Demographic History ◽  
Population Decline ◽  
Mountain Range ◽  
Population Demography ◽  
High Genetic Diversity ◽  
Nuclear Microsatellite ◽  
Over Exploitation

Tetraena mongolica Maxim (Zygophyllaceae) is an endangered species endemic to western Inner Mongolia and China, and is currently threatened by habitat loss and human over-exploitation. We explored the genetic background, its genetic diversity, population structure, and demographic history, based on 12 polymorphic nuclear microsatellite loci. Our results indicated high genetic diversity in extant populations, but no distinguishable gene cluster corresponding with a specific biogeography. Population demography analysis using a MSVAR indicated a strong, recent population decline approximately 5,455 years ago. These results suggest that the Yellow River and Zhuozi Mountain range may not prevent pollination between populations. Finally, we surmised that the population demography of T. mongolica was likely to have been affected by early mankind activities.

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