Corrigendum to: Inbreeding and testicular abnormalities in a bottlenecked population of koalas (Phascolarctos cinereus)

2012 ◽  
Vol 39 (4) ◽  
pp. 374 ◽  
Author(s):  
Romane Cristescu ◽  
Valma Cahill ◽  
William B. Sherwin ◽  
Kathrine Handasyde ◽  
Kris Carlyon ◽  
...  
Keyword(s):  
Small Population ◽  
Habitat Destruction ◽  
Island Population ◽  
Population Bottlenecks ◽  
Subsequent Increase ◽  
Phascolarctos Cinereus ◽  
Success Stories ◽  
Low Genetic Diversity ◽  
Deleterious Alleles ◽  
High Prevalence

Habitat destruction and fragmentation, interactions with introduced species or the relocation of animals to form new populations for conservation purposes may result in a multiplication of population bottlenecks. Examples are the translocations of koalas to French Island and its derivative Kangaroo Island population, with both populations established as insurance policies against koala extinction. In terms of population size, these conservation programs were success stories. However, the genetic story could be different. We conducted a genetic investigation of French and Kangaroo Island koalas by using 15 microsatellite markers, 11 of which are described here for the first time. The results confirm very low genetic diversity. French Island koalas have 3.8 alleles per locus and Kangaroo Island koalas 2.4. The present study found a 19% incidence of testicular abnormality in Kangaroo Island animals. Internal relatedness, an individual inbreeding coefficient, was not significantly different in koalas with testicular abnormalities from that in other males, suggesting the condition is not related to recent inbreeding. It could instead result from an unfortunate selection of founder individuals carrying alleles for testicular abnormalities, followed by a subsequent increase in these alleles' frequencies through genetic drift and small population-related inefficiency of selection. Given the low diversity and possible high prevalence of deleterious alleles, the genetic viability of the population remains uncertain, despite its exponential growth so far. This stands as a warning to other introductions for conservation reasons.

Inbreeding and testicular abnormalities in a bottlenecked population of koalas (Phascolarctos cinereus)

2009 ◽  
Vol 36 (4) ◽  
pp. 299 ◽  
Author(s):  
Romane Cristescu ◽  
Valma Cahill ◽  
William B. Sherwin ◽  
Kathrine Handasyde ◽  
Kris Carlyon ◽  
...  
Keyword(s):  
Small Population ◽  
Habitat Destruction ◽  
Island Population ◽  
Population Bottlenecks ◽  
Subsequent Increase ◽  
Phascolarctos Cinereus ◽  
Success Stories ◽  
Low Genetic Diversity ◽  
Deleterious Alleles ◽  
High Prevalence

Habitat destruction and fragmentation, interactions with introduced species or the relocation of animals to form new populations for conservation purposes may result in a multiplication of population bottlenecks. Examples are the translocations of koalas to French Island and its derivative Kangaroo Island population, with both populations established as insurance policies against koala extinction. In terms of population size, these conservation programs were success stories. However, the genetic story could be different. We conducted a genetic investigation of French and Kangaroo Island koalas by using 15 microsatellite markers, 11 of which are described here for the first time. The results confirm very low genetic diversity. French Island koalas have 3.8 alleles per locus and Kangaroo Island koalas 2.4. The present study found a 19% incidence of testicular abnormality in Kangaroo Island animals. Internal relatedness, an individual inbreeding coefficient, was not significantly different in koalas with testicular abnormalities from that in other males, suggesting the condition is not related to recent inbreeding. It could instead result from an unfortunate selection of founder individuals carrying alleles for testicular abnormalities, followed by a subsequent increase in these alleles’ frequencies through genetic drift and small population-related inefficiency of selection. Given the low diversity and possible high prevalence of deleterious alleles, the genetic viability of the population remains uncertain, despite its exponential growth so far. This stands as a warning to other introductions for conservation reasons.

Low genetic diversity and inbreeding depression in Queensland Koalas

1993 ◽  
Vol 20 (2) ◽  
pp. 177 ◽  
Author(s):  
JMW Wilmer ◽  
A Melzer ◽  
F Carrick ◽  
C Moritz
Keyword(s):  
Genetic Diversity ◽  
Mitochondrial Dna ◽  
Inbreeding Depression ◽  
Natural Populations ◽  
Small Population ◽  
Phascolarctos Cinereus ◽  
Low Genetic Diversity ◽  
History Of ◽  
Biased Sex Ratio ◽  
Two Populations

The amount of genetic variation in two natural populations of Queensland koalas (Phascolarctos cinereus adustus) was assessed by analysis of mitochondrial DNA. Levels and any adverse effects of inbreeding (inbreeding depression) were estimated from the pedigree of a well-characterised captive colony. Genetic diversity of mitochondrial DNA was found to be exceedingly low both within and between the two populations, but the variation detected was found to be strongly structured geographically. Inbreeding levels in the captive colony were moderate to high yet the only apparent evidence of inbreeding depression was a male-biased sex ratio. There was no evidence for decreased juvenile survivorship or growth rate with inbreeding. Because of the limited data it would be premature to conclude that koalas are relatively resistant to the effects of inbreeding. However, we suggest the hypothesis that koalas have a history of small population size, resulting in reduced susceptibility to inbreeding depression.

scholarly journals A review of climatic change as a determinant of the viability of koala populations

2017 ◽  
Vol 44 (7) ◽  
pp. 458 ◽  
Author(s):  
Hailee J. Reckless ◽  
Michael Murray ◽  
Mathew S. Crowther
Keyword(s):  
Climate Change ◽  
Climate Extremes ◽  
Habitat Destruction ◽  
Toxic Chemicals ◽  
Conservation Strategies ◽  
Local Conservation ◽  
Phascolarctos Cinereus ◽  
Low Genetic Diversity ◽  
Anthropogenic Processes ◽  
The Impact

The koala (Phascolarctos cinereus) occupies a broad range of eastern and southern Australia, extending over tropical coastal, semiarid inland and temperate regions. In many areas koala populations are under threat, in particular from the direct and indirect effects of ongoing habitat destruction due to increased urbanisation and other anthropogenic processes. Climate change presents additional threats to the integrity of koala habitats because many species of food and non-food trees have narrow climate envelopes and are unable to adapt to altered temperatures and rainfall. Climate extremes also produce physiological stresses in koalas that may increase the likelihood of outbreaks of chlamydiosis and other diseases. Climate change–related increases in the relative content of toxic chemicals in leaves are further stresses to the koala after ingestion. In addition, populations that originated from a small number of founder individuals are at potential risk due to their relatively low genetic diversity. Strategies that maintain residual habitat fragments and promote the construction of new refugia are now being formulated. Modelling of the impact of habitat metrics on koala distribution is providing important information that can be used in the rehabilitation of koala refugia. In future these models could be augmented with metrics that describe koala homeostasis to inform local conservation strategies. These considerations are also relevant for the maintenance of other taxa in the wider ecosystem that are also at risk from habitat destruction and climate change.

scholarly journals Estimates of genetic load in small populations suggest extensive purging of deleterious alleles

2019 ◽  
Author(s):  
Tom van der Valk ◽  
Marc de Manuel ◽  
Tomas Marques-Bonet ◽  
Katerina Guschanski
Keyword(s):  
Large Population ◽  
Genetic Load ◽  
Small Population ◽  
Small Populations ◽  
Population Declines ◽  
Current Conservation ◽  
Low Genetic Diversity ◽  
Deleterious Alleles ◽  
Declining Populations ◽  
Genetic Purging

AbstractDeclining populations are expected to experience negative genetic consequences of inbreeding, which over time can drive them to extinction. Yet, many species have survived in small populations for thousands of generations without apparent fitness effects, possibly due to genetic purging of partially deleterious recessive alleles in inbred populations. We estimate the abundance of deleterious alleles in a range of mammals and find that conversely to current conservation thinking species with historically small population size and low genetic diversity generally have lower genetic load compared to species with large population sizes. Rapid population declines will thus disproportionally affect species with high diversity, as they carry many deleterious alleles that can reach fixation before being removed by genetic purging.

Season of birth interacts with measures of inbreeding in multiplex schizophrenia pedigrees: evidence from genetic isolates in Daghestan

Open Medicine ◽  
2006 ◽  
Vol 1 (4) ◽  
pp. 392-398
Author(s):  
Kazima Bulayeva ◽  
John McGrath
Keyword(s):  
Genetic Diversity ◽  
Family History ◽  
Age Of Onset ◽  
Population Genetic Study ◽  
Season Of Birth ◽  
High Genetic Diversity ◽  
Low Genetic Diversity ◽  
High Prevalence ◽  
History Of ◽  
Genetic Isolates

AbstractWhile the season-of-birth effect is one of the most consistent epidemiological features of schizophrenia, there is a lack of consistency with respect to the interaction between season of birth and family history of schizophrenia. Apart from family history, measures related to consanguinity can be used as proxy markers of genomic heterogeneity. Thus, these measures may provide an alternate, indirect index of genetic susceptibility. We had the opportunity to explore the interaction between season of birth and measure of consanguinity in well-described genetic isolates in Daghestan, some of which are known for their relatively high prevalence of schizophrenia. Our previous population-genetic study showed Daghestan has an extremely high genetic diversity between the ethnic populations and a low genetic diversity within them. The isolates selected for this study include some with more than 200 and some with less than 100 generations of demographical history since their founding. Based on pedigrees of multiply-affected families, we found that among individuals with schizophrenia, the measure of consanguinity was significantly higher in the parents of those born in winter/spring compared to those born in summer/autumn. Furthermore, compared to summer/autumn born, winter/spring born individuals with schizophrenia had an earlier age-of-onset, and more prominent auditory hallucinations. Our results suggest that the offspring of consanguineous marriages, and thus those with reduced allelic heterogeneity, may be more susceptible to the environmental factor(s) underpinning the season-of-the effect in schizophrenia.

Genetic diversity in natural and introduced island populations of koalas in Queensland

2012 ◽  
Vol 60 (5) ◽  
pp. 303 ◽  
Author(s):  
Kristen E. Lee ◽  
Jennifer M. Seddon ◽  
Stephen Johnston ◽  
Sean I. FitzGibbon ◽  
Frank Carrick ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Allelic Richness ◽  
Island Population ◽  
Founder Effects ◽  
Phascolarctos Cinereus ◽  
Island Populations ◽  
The North ◽  
Mitochondrial Haplotypes ◽  
Naturally Occurring ◽  
Microsatellite Alleles

Island populations of animals are expected to show reduced genetic variation and increased incidence of inbreeding because of founder effects and the susceptibility of small populations to the effects of genetic drift. Koalas (Phascolarctos cinereus) occur naturally in a patchy distribution across much of the eastern Australian mainland and on a small number of islands near the Australian coast. We compared the genetic diversity of the naturally occurring population of koalas on North Stradbroke Island in south-east Queensland with other island populations including the introduced group on St Bees Island in central Queensland. The population on St Bees Island shows higher diversity (allelic richness 4.1, He = 0.67) than the North Stradbroke Island population (allelic richness 3.2, He = 0.55). Koalas on Brampton, Newry and Rabbit Islands possessed microsatellite alleles that were not identified from St Bees Island koalas, indicating that it is most unlikely that these populations were established by a sole secondary introduction from St Bees Island. Mitochondrial haplotypes on the central Queensland islands were more similar to a haplotype found at Springsure in central Queensland and the inland clades in south-east Queensland, rather than the coastal clade in south-east Queensland.

scholarly journals Tumors in St. Lawrence Beluga Whales (Delphinapterus leucas)

1994 ◽  
Vol 31 (4) ◽  
pp. 444-449 ◽  
Author(s):  
S. De Guise ◽  
A. Lagacé ◽  
P. Béland
Keyword(s):  
Small Population ◽  
Delphinapterus Leucas ◽  
Carcinogenic Effect ◽  
Lawrence Estuary ◽  
Beluga Whales ◽  
High Prevalence ◽  
Endangered Population ◽  
High Concentrations ◽  
St Lawrence Estuary ◽  
St Lawrence River

A population of 450–500 belugas ( Delphinapterus leucas) resides in the polluted estuary of the St. Lawrence River. Stranded carcasses of this endangered population were recovered and necropsied. High concentrations of organochlorines, heavy metals, and benzo-a-pyrene exposure were demonstrated in tissues of these whales. Between 1988 and 1990, 21 tumors were found in 12 out of 24 carcasses. Among these tumors, six were malignant and 15 were benign. The animals were between 1.5 and >29 years of age, and the ages of animals with and without tumors did not differ when two juvenile animals (1.5 and 3.5 years of age) were excluded. Seven other neoplasms had been reported previously in six out of 21 well-preserved carcasses examined in the same laboratory between 1982 and 1987. Overall, 28 of the 75 confirmed tumors reported so far in cetaceans (37%) were from this small population of beluga whales in the St. Lawrence Estuary. Such a high prevalence of tumors would suggest an influence of contaminants through a direct carcinogenic effect and/or a decreased resistance to the development of tumors in this population.

scholarly journals Phylogeographic Analysis Suggests a Recent Population Bottleneck in the Rare Red Sea Tridacna squamosina

2021 ◽  
Vol 8 ◽  
Author(s):  
Kah Kheng Lim ◽  
Susann Rossbach ◽  
Nathan R. Geraldi ◽  
Ester A. Serrão ◽  
Carlos M. Duarte
Keyword(s):  
Genetic Diversity ◽  
Red Sea ◽  
Coastal Zone Management ◽  
Small Population ◽  
Zone Management ◽  
Low Genetic Diversity ◽  
Giant Clams ◽  
Management Plans ◽  
Tridacna Maxima ◽  
Distribution And Ecology

Giant clams are an important ecological component of coral reefs in the Red Sea, as they enhance the reef’s productivity and provide habitat that can increase diversity. Three species of giant clams, namely Tridacna maxima, T. squamosa, and T. squamosina have been described within the Red Sea. However, due to its scarcity, information about the distribution and ecology of T. squamosina in the Saudi Arabian Red Sea is still lacking. This study used DNA barcoding to confirm the identity of the rare T. squamosina in the Farasan Banks. Six mtCOI fragments (500 bp) of T. squamosina were successfully amplified using the SQUA-primers for the first time. We used our data along with 18 reference sequences (16S) from the online database to assess the genetic diversity and population structure of T. squamosina. Low genetic diversity among the T. squamosina populations inferred from the 16S sequences implies a recent bottleneck for this species, which is supported by their historically higher diversity based on the coalescent-based estimator. Given the small population abundance and limited genetic variation of T. squamosina, it may warrant immediate local protections such as biobanking and fertility preservation programs as well as effective integrated coastal zone management plans.

scholarly journals Mutation load decreases with haplotype age in wild Soay sheep

2021 ◽  
Author(s):  
M.A. Stoffel ◽  
S.E. Johnston ◽  
J.G. Pilkington ◽  
J.M Pemberton
Keyword(s):  
Inbreeding Depression ◽  
Purifying Selection ◽  
Small Population ◽  
First Year ◽  
Mutation Load ◽  
Soay Sheep ◽  
Recessive Mutations ◽  
Deleterious Alleles ◽  
Lower Population

AbstractRuns of homozygosity (ROH) are pervasive in diploid genomes and expose the effects of deleterious recessive mutations, but how exactly these regions contribute to variation in fitness remains unclear. Here, we combined empirical analyses and simulations to explore the deleterious effects of ROH with varying genetic map lengths in wild Soay sheep. Using a long-term dataset of 4,592 individuals genotyped at 417K SNPs, we found that inbreeding depression increases with ROH length. A 1% genomic increase in long ROH (>12.5cM) reduced the odds of first-year survival by 12%, compared to only 7% for medium ROH (1.56-12.5cM), while short ROH (<1.56cM) had no effect on survival. We show by forward genetic simulations that this is predicted: compared with shorter ROH, long ROH will have higher densities of deleterious alleles, with larger average effects on fitness and lower population frequencies. Taken together, our results are consistent with the idea that the mutation load decreases in older haplotypes underlying shorter ROH, where purifying selection has had more time to purge deleterious mutations. Finally, our study demonstrates that strong inbreeding depression can persist despite ongoing purging in a historically small population.

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