Low effective population size in the genetically bottlenecked Australian sea lion is insufficient to maintain genetic variation

2021 ◽  
Author(s):  
K. Bilgmann ◽  
N. Armansin ◽  
A.L. Ferchaud ◽  
E. Normandeau ◽  
L. Bernatchez ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Population Size ◽  
Effective Population Size ◽  
Effective Population ◽  
Sea Lion ◽  
Australian Sea Lion

Genetic variation in a semi-natural Drosophila population after a bottleneck I. Lethals, their allelism and effective population size

Genetica ◽  
1985 ◽  
Vol 66 (1) ◽  
pp. 11-20 ◽  
Author(s):  
M. Begon ◽  
R. Chadburn ◽  
J. A. Bishop ◽  
C. Keill
Keyword(s):  
Genetic Variation ◽  
Population Size ◽  
Effective Population Size ◽  
Effective Population

High genetic variation in leopards indicates large and long-term stable effective population size

2000 ◽  
Vol 9 (11) ◽  
pp. 1773-1782 ◽  
Author(s):  
G. Spong ◽  
M. Johansson ◽  
M. Björklund
Keyword(s):  
Genetic Variation ◽  
Population Size ◽  
Effective Population Size ◽  
Effective Population

scholarly journals The effects of X-rays on quantitative characters

1964 ◽  
Vol 5 (3) ◽  
pp. 410-422 ◽  
Author(s):  
G. A. Clayton ◽  
Alan Robertson
Keyword(s):  
Genetic Variation ◽  
Population Size ◽  
Effective Population Size ◽  
Artificial Selection ◽  
Inbred Lines ◽  
X Rays ◽  
Effective Population ◽  
Outbred Population ◽  
Culture Bottle ◽  
Quantitative Characters

1. The rate of production by X-rays of new genetic variation in two quantitative characters in Drosophila melanogaster (sternital and sternopleural bristles) has been investigated, using ‘plateaued’ populations which had reached the limit under artificial selection and, for sternital bristles only, populations which had been made genetically invariant by inbreeding. The genetic variation was always measured by the response of the population to selection. The X-rays dose given in any generation was always 1800 r. to adults.2. Seven plateaued lines had eight cycles of alternate irradiation and selection, each with its non-irradiated control. All the responses were small but in three lines they were significantly greater after irradiation.3. Selection was applied to three different inbred lines, genetically marked to detect contamination, after varying periods of irradiation. At the same time, the inbred lines and lines derived from them which had been mass mated in bottles were selected. The irradiated populations showed a greater response. The new genetic variance produced by the irradiation was approximately 10−5 units/r. The estimate of the dose required to introduce new variation equal to that in a standard outbred population was 500,000 r.4. The effective population size was an important factor in the interpretation of some of these results on the long-term effects of radiation. By observing the variation between replicate lines in the frequency of a gene with a visible effect under these culture conditions (i.e. in a single culture bottle) the effective population size was estimated at sixty. Outbred populations kept under these conditions for many generations showed a reduction of genetic variability in agreement with this value.5. To investigate the possibility that the deleterious genes produced by irradiation would interfere with the response to artificial selection, a standard outbred population was irradiated and selected. In spite of the observed high frequency of recessive lethals produced, the response to selection was very similar to that of the standard population.

scholarly journals Historical population size of the threatened New Zealand sea lion Phocarctos hookeri

2015 ◽  
Vol 97 (2) ◽  
pp. 436-443 ◽  
Author(s):  
Catherine J. Collins ◽  
B. Louise Chilvers ◽  
Matthew Taylor ◽  
Bruce C. Robertson
Keyword(s):  
New Zealand ◽  
Population Size ◽  
Effective Population Size ◽  
Carrying Capacity ◽  
Effective Population ◽  
Sea Lion ◽  
Sea Lions ◽  
Target Values ◽  
Phocarctos Hookeri

Abstract Marine mammal species were exploited worldwide during periods of commercial sealing in the 18th and 19th centuries. For many of these species, an estimate of the pre-exploitation abundance of the species is lacking, as historical catch records are generally scarce and inaccurate. Genetic estimates of long-term effective population size provide a means to estimate the pre-exploitation abundance. Here, we apply genetic methods to estimate the long-term effective population size of the subantarctic lineage of the New Zealand sea lion (NZ sea lion), Phocarctos hookeri . This species is predominantly restricted to the subantarctic islands, south of mainland New Zealand, following commercial sealing in the 19th century. Today, the population consists of ~9,880 animals and population growth is slow. Auckland Island breeding colonies of NZ sea lion are currently impacted by commercial trawl fisheries via regular sea lion deaths as bycatch. In order to estimate sustainable levels of bycatch, an estimate of the population’s carrying capacity ( K ) is required. We apply the genetically estimated long-term effective population size of NZ sea lions as a proxy for the estimated historical carrying capacity of the subantarctic population. The historical abundance of subantarctic NZ sea lions was significantly higher than the target values of K employed by the contemporary management. The current management strategy may allow unsustainable bycatch levels, thereby limiting the recovery of the NZ sea lion population toward historical carrying capacity.

scholarly journals Interrelations between effective population size and other pedigree tools for the management of conserved populations

2000 ◽  
Vol 75 (3) ◽  
pp. 331-343 ◽  
Author(s):  
ARMANDO CABALLERO ◽  
MIGUEL A. TORO
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Population Size ◽  
Effective Population Size ◽  
Genetic Parameters ◽  
Effective Number ◽  
Effective Population ◽  
Clear Cut ◽  
Captive Populations ◽  
Practical Recommendations

Genetic parameters widely used to monitor genetic variation in conservation programmes, such as effective number of founders, founder genome equivalents and effective population size, are interrelated in terms of coancestries and variances of contributions from ancestors to descendants. A new parameter, the effective number of non-founders, is introduced to describe the relation between effective number of founders and founder genome equivalents. Practical recommendations for the maintenance of genetic variation in small captive populations are discussed. To maintain genetic diversity, minimum coancestry among individuals should be sought. This minimizes the variances of contributions from ancestors to descendants in all previous generations. The method of choice of parents and the system of mating should be independent of each other because a clear-cut recommendation cannot be given on the latter.

scholarly journals Genetic Variation, Relatedness, and Effective Population Size of Polar Bears (Ursus maritimus) in the southern Beaufort Sea, Alaska

2009 ◽  
Vol 100 (6) ◽  
pp. 681-690 ◽  
Author(s):  
Matthew A. Cronin ◽  
Steven C. Amstrup ◽  
Sandra L. Talbot ◽  
George K. Sage ◽  
Kristin S. Amstrup
Keyword(s):  
Genetic Variation ◽  
Population Size ◽  
Effective Population Size ◽  
Beaufort Sea ◽  
Ursus Maritimus ◽  
Polar Bears ◽  
Effective Population

Genetic variation and effective population size in isolated populations of coastal cutthroat trout

2010 ◽  
Vol 11 (5) ◽  
pp. 1929-1943 ◽  
Author(s):  
Andrew R. Whiteley ◽  
Kim Hastings ◽  
John K. Wenburg ◽  
Chris A. Frissell ◽  
Jamie C. Martin ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Population Size ◽  
Effective Population Size ◽  
Cutthroat Trout ◽  
Effective Population ◽  
Isolated Populations ◽  
Coastal Cutthroat Trout
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