How many founders, how large a population?

Willis, Kevin; Willis, Raymond E.

doi:10.1002/zoo.20310

Cited by 9 publications

(9 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, captive breeding and translocations can play a vital role in the recovery of a species by providing a "rescue" mechanism to populations under immediate threat [27,28]. Before establishing captive breeding and translocation programs, consideration of key factors is prudent: (i) how many founding populations would be necessary to capture the population structure and diversity present in the wild, (ii) which wild "source" populations have large and stable abundance and could best tolerate loss of individuals (for captive breeding or translocation efforts) without compromising viability [29,30], and (iii) which life stages should be taken from source populations to minimize effects to those populations and conversely, which life stages could be used to most effectively establish or augment populations [31].…”

Section: Introductionmentioning

confidence: 99%

Combining genetic and demographic monitoring better informs conservation of an endangered urban snake

et al. 2020

View full text Add to dashboard Cite

Conversion and fragmentation of wildlife habitat often leads to smaller and isolated populations and can reduce a species' ability to disperse across the landscape. As a consequence, genetic drift can quickly lower genetic variation and increase vulnerability to extirpation. For species of conservation concern, quantification of population size and connectivity can clarify the influence of genetic drift in local populations and provides important information for conservation management and recovery strategies. Here, we used genome-wide single nucleotide polymorphism (SNP) data and capture-mark-recapture methods to evaluate the genetic diversity and demography within seven focal sites of the endangered San Francisco gartersnake (Thamnophis sirtalis tetrataenia), a species affected by alteration and isolation of wetland habitats throughout its distribution. The primary goals were to determine the population structure and degree of genetic isolation among T. s. tetrataenia populations and estimate effective size and population abundance within sites to better understand the present and future importance of genetic drift. We also used temporally sampled datasets to examine the magnitude of genetic change over time. We found moderate population genetic structure throughout the San Francisco Peninsula that partitions sites into northern and southern regional clusters. Point estimates of both effective size and population abundance were generally small (� 100) for a majority of the sites, and estimates were particularly low in the northern populations. Genetic analyses of temporal datasets indicated an increase in genetic differentiation, especially for the most geographically isolated sites, and decreased genetic diversity over time in at least one site (Pacifica). Our results suggest that drift-mediated processes as a function of small population size and reduced connectivity from neighboring populations may decrease diversity and increase differentiation. Improving genetic diversity and connectivity among T. s. tetrataenia populations could promote persistence of this endangered snake.

show abstract

Section: Introductionmentioning

confidence: 99%

Combining genetic and demographic monitoring better informs conservation of an endangered urban snake

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The relationship between G and A is essentially the same as the relationship between the number of population founders and the population size. Willis and Willis [] evaluated that relationship to determine the optimal combined values of those two variables using a predetermined goal of retaining a given amount of gene diversity for a given amount of time. They found that because the number of founders will almost always be less the than total population size, a slight increase in the number of effective founders will almost always produce a greater impact on gene diversity retention than a similar increase in the total population size.…”

Section: Methodsmentioning

confidence: 99%

Use of animals with partially known ancestries in scientifically managed breeding programs

Willis

Lacy

2016

Zoo Biology

Self Cite

View full text Add to dashboard Cite

Animals with only partially known ancestry present a problem for population managers because it can be difficult to determine their relative genetic value to the population. So long as their ancestry is not completely unknown, population management software such as PMx can calculate a mean kinship for these animals, but that mean kinship is calculated such that there is no decrease in relative genetic value or "penalty" for only partially known ancestry. However, there is a longer-term genetic cost to having animals with only partially known ancestry in the population, and thus it is appropriate to "penalize" animals with partially known ancestry to some extent. The challenge is determining the correct "penalty" which will serve to decrease the percent unknown ancestry in subsequent generations while not causing excessive selection against the known ancestry of the animal. A new parameter of relative genetic value is developed which takes into account both an animal's mean kinship as well as its percent known ancestry. The method used in PMx to calculate the mean kinships also in general overestimates the inbreeding coefficients of offspring of animals with partially known ancestry when the known parents share a common ancestor, but can underestimate inbreeding if common ancestors exist within the unknown portion of the pedigree. This may result in population managers selecting less suitable pairs for breeding in an attempt to avoid an apparent higher level of inbreeding. A parameter is developed that adjusts the inbreeding coefficient to more accurately reflect the likely inbreeding coefficient of potential offspring. Zoo Biol. 35:319-325, 2016. © 2016 Wiley Periodicals, Inc.

show abstract

“…When a captive breeding program is recommended, the number of initial founders and the correct selection of individuals to maximize genetic diversity are key factors, as they will determine the genetic diversity present in the captive population (Frankham, Ballou & Briscoe, 2010; Mace, Pemberton & Stanley, 1992; Senner, 1980; Willis & Willis, 2010). Captive populations can often only represent a small subset of a natural population due to spatial or financial limitations of the organizations that manage them (Willoughby et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Getting off to a good start? Genetic evaluation of the ex situ conservation project of the Critically Endangered Montseny brook newt (Calotriton arnoldi)

Valbuena-Ureña

Soler-Membrives

Steinfartz

et al. 2017

PeerJ

View full text Add to dashboard Cite

Ex situ management strategies play an important role in the conservation of threatened species when the wild survival of the species cannot be ensured. Molecular markers have become an outstanding tool for the evaluation and management of captive breeding programs. Two main genetic objectives should be prioritized when planning breeding programs: the maintenance of maximum neutral genetic diversity, and to obtain “self-sustaining” captive populations. In this study, we use 24 microsatellite loci to analyze and evaluate the genetic representativity of the initial phases of the captive breeding program of the Montseny brook newt, Calotriton arnoldi, an Iberian endemic listed as Critically Endangered. The results show that the initial captive stock has 74–78% of the alleles present in the wild populations, and captures roughly 93–95% of their total genetic diversity as observed in a previous study on wild newts, although it does not reach the desired 97.5%. Moreover, the percentage of unrelatedness among individuals does not exceed 95%. Therefore, we conclude that the genetic diversity of the captive stock should be improved by incorporating genetic material from unrelated wild newts. In recognition of the previously described significant genetic and morphological differentiation between eastern and western wild populations of C. arnoldi, we suggest maintaining two distinct breeding lines, and we do not recommend outbreeding between these lines. Our comparisons of genetic diversity estimates between real and distinct sample-sized simulated populations corroborated that a minimum of 20 individuals are needed for each captive population, in order to match the level of genetic diversity present in the wild populations. Thus, the current initial stock should be reinforced by adding wild specimens. The captive stock and subsequent cohorts should be monitored in order to preserve genetic variation. In order to avoid genetic adaptation to captivity, occasionally incorporating previously genotyped individuals from the wild into the captive populations is recommended.

show abstract

How many founders, how large a population?

Cited by 9 publications

References 6 publications

Combining genetic and demographic monitoring better informs conservation of an endangered urban snake

Combining genetic and demographic monitoring better informs conservation of an endangered urban snake

Use of animals with partially known ancestries in scientifically managed breeding programs

Getting off to a good start? Genetic evaluation of the ex situ conservation project of the Critically Endangered Montseny brook newt (Calotriton arnoldi)

Contact Info

Product

Resources

About