Research and analysis

UKGLE advice on native breed conservation

Published 2 June 2025

1. Introduction

This paper sets out the UK Genetics for Livestock and Equines (UKGLE) Committee’s advice on native breed conservation. It draws on international best practice, including the United Nations Food and Agriculture Organization (FAO) guidelines, information and evidence relating to native breed conservation. This advice contributes to the Call for Evidence regarding proposed amendments to the UK’s native breeds at risk (NBAR) list. The committee’s advice represents a first step in addressing some immediate areas of relevance.

2. Scope and rationale for native breed conservation

Background

The Convention on Biological Diversity (CBD) is a multi-lateral treaty that entered into force on 29 December 1993. The 3 main objectives are:

• the conservation of biological diversity
• the sustainable use of the components of biological diversity
• the fair and equitable sharing of the benefits arising out of the utilisation of genetic resources

The United Kingdom government ratified the treaty in 1994 and has been a party to the convention for the last 30 years.

In 2002, the UK submitted its first country report on Farm Animal Genetic Resources (FAnGR) as part of the State of the World’s Animal Genetic Resources report commissioned by the FAO. This classified UK breeds as native and non-native, recommending that support for the conservation of native breeds should be a national priority.

In 2004, a National Steering Committee (NSC) for FAnGR was established to set priorities for and advise on the implementation of the UK National Action Plan on FAnGR as recommended in the UK Country Report on FAnGR 2002. The NSC drafted and published the UK National Action Plan in 2006. This recognised that support for all listed breeds in the National Breed Inventory would create enormous financial demands and indicated the need for prioritisation. The UK National Action Plan set out targets for the characterisation, monitoring and prioritisation for breeds for conservation.

In 2007, the United Kingdom was one of the 109 countries that adopted The Global Plan of Action for Animal Genetic Resources at the International Technical Conference on Animal Genetic Resources, held in Interlaken, Switzerland. The declaration recognises that directed selection by smallholders, farmers, pastoralists and breeders, throughout the world and, over generations has resulted in a wide variety of livestock breeds. These breeds provide a diverse stream of benefits to the environment, humanity and its cultural heritage. All countries will need to play their part in conserving these resources as a basis for livestock development, food security and the better nutrition of their rural and urban populations, as well as to sustain their rural communities.

In 2010, at the Convention of the Parties to the CBD in Nagoya Japan a set of targets for 2020 were agreed – the Aichi Biodiversity Targets. Target 13 sets out the importance of maintaining genetic diversity and minimising genetic erosion in farmed livestock.

Target 13

See the quick guide to the Aichi Biodiversity Targets – Target 13.

By 2020, the genetic diversity of cultivated plants and farmed and domesticated animals and of wild relatives, including other socio-economically as well as culturally valuable species, is maintained, and strategies have been developed and implemented for minimising genetic erosion and safeguarding their genetic diversity.

In September 2015 the 17 Global Goals for Sustainable Development were agreed by 193 member states of the United Nations (UN). The UK was at the forefront of negotiating the goals and committed to be at the forefront of delivering these both at home and around the world.

Sustainable Development Goal 2.5 states that the genetic diversity of seeds, cultivated plants and farmed and domesticated animals must be maintained.

The indicators used to measure progress were defined as:

2.5.1 Number of plant and animal genetic resources for food and agriculture secured in medium or long-term conservation facilities.

2.5.2 Proportion of local breeds, classified as being at risk, not-at-risk or unknown level of risk of extinction.

In December 2022, the Kunming-Montreal Global Biodiversity Framework (GBF) was adopted during the 15th meeting of the Conference of the Parties (COP 15) following a four-year consultation and negotiation process. This historic framework, which supports the achievement of the Sustainable Development Goals and builds on the convention’s previous strategic plans, sets out an ambitious pathway to reach the global vision of a world living in harmony with nature by 2050.

Among the framework’s key elements are 4 goals for 2050 and 23 targets for 2030. Target 4 aims to “maintain and restore the genetic diversity within and between populations of native, wild and domesticated species to maintain their adaptive potential, including through in situ and ex situ conservation and sustainable management practices”.

These international agreements, to which the UK is a signatory, set out the framework on which UKGLE advice on Native Breed Conservation is based.

One of the key objectives of the FAO’s Global Plan of Action for Animal Genetic Resources is to protect and sustainably use animal genetic resources, including native and locally adapted breeds, which are often well-adapted to specific environmental conditions.

The framework highlights that native breeds play a crucial role in biodiversity conservation and food security, especially in the face of challenges like climate change and disease outbreaks (FAO, 2007).

The committee advise that, as a signatory of the CBD and in line with the GBF, prioritisation of resources to support domestic livestock genetic resource conservation should focus on native breeds.

3. Recommended conservation strategy: whole-breed approach

The international agreements and frameworks described above consistently refer to breeds in the context of conservation of farmed livestock.

FAO Guidelines on Conservation (FAO, 2013) refer throughout to the breed as the unit of conservation. The more recent publication on cryo-conservation in 2023 recognises that “breed is an important determinant for both the global livestock sector and collection development” and goes on to state that “while some attempts (e.g. Weitzman, 1998) have been made to use genetic markers to develop subsets of breeds to capture a broad array of genetic diversity per species, such approaches do not account for the need to service the broader community of stakeholders, and have generally not been implemented because of a lack of consensus of stakeholders on the subsets (Boettcher and others 2010).” (Boes, J. and others, 2023).

The UKGLE Committee recognises the importance of genetic diversity within breeds. UKGLE recommend that UK Government prioritise support at breed level and, recognising the context of limited public resources for native breed conservation, that the whole breed should be the focus of conservation support rather than subsets of breeds such as Original Populations (OPs). This follows previous UKGLE advice that conservation policy should focus on the genetic diversity of the entire breed, rather than subpopulations.

The definition of a breed, contained within regulation (EU) 2016/1012 (assimilated UK law) is: 

“a population of animals sufficiently uniform to be considered to be distinct from other animals of the same species by one or more groups of breeders which have agreed to enter those animals in breeding books with details of their known ascendants for the purpose of reproducing their inherited characteristics by way of reproduction, exchange and selection within the framework of a breeding programme.”

For the purposes of the UK National Breed Inventory, Defra, informed by UKGLE advice, have set out the definition of a ‘breed’ as, “An interbreeding population of husbanded domesticated animals of consistent genotype and phenotype with a recognised history and administrative framework”. Breeds are recognised as being native to the UK if they can demonstrate breed origin within the UK (including from an amalgamation of native breeds), and that the UK has formed the primary environment for the development of the breed, among other specific criteria.

The status of a breed in the National Breed Inventory defines its eligibility for the ‘at risk’ lists.

3.1 Scientific rationale for whole-breed approach to conservation

FAO guidelines

The FAO has consistently recommended that the unit of conservation should be the whole breed (FAO, 2007). This highlights the critical importance of preserving genetic diversity within a wide gene pool. A diverse genetic base is essential for mitigating the risks associated with inbreeding, genetic drift, and the emergence of detrimental traits that can occur when populations are split into smaller sub-groups.

The value of genetic diversity

Maintaining a broad gene pool is vital because it helps to ensure the overall health and resilience of a breed. Inbreeding, which often results from the isolation of smaller populations for breeding, can lead to a reduction in genetic variability, making animals more susceptible to diseases and reducing their ability to adapt to changing environmental conditions. Inbred populations are more likely to express negative genetic traits including reduced fertility, lower growth rates, and compromised immune function impacting on animal health.

UKGLE recognises these genetic risks and advocates a whole-breed conservation strategy.

3.2 Original populations (OPs)

The government approach for the conservation of native breeds has, for most species, focused on whole breeds, leaving the responsibility for managing sub populations with breed societies or specific groups of breeders. The government updates the NBAR list which lists breeds that meet the criteria to be considered ‘at risk’ and therefore eligible for claiming agri-environment payments. The definition of ‘breed’ used for the UK National Breed Inventory on gov.uk reflects UKGLE advice framed around the whole breed approach. The definition indicates that subpopulations with phenotypes attributable to single or minor trait differences will not be recognised. UKGLE advise that it is a matter for individual breed societies to decide whether they wish to register separate subpopulations based on differences in phenotypes within their breeding book.

Some breed societies have opted to list ‘original populations’ (OPs) within their herd books. OPs refer to subpopulations of a breed that a group of breeders wish to maintain within a breed. There are no agreed international definitions of OPs and as described above the lack of consensus on subsets has resulted in the FAO recommendation that the breed should be the unit of conservation. This led the committee to review how these OPs should be represented in the National Breed Inventory and ‘at risk’ lists it informs.

Responsibility of breed societies

The committee advise that the government should follow the recommendations of the FAO, establishing the base unit for conservation policy as the whole breed. Breeds are managed by breed societies, which can be formally recognised under Zootech legislation. In line with Zootech legislation the committee does not recommend having more than one breed society for any breed, emphasising that the entire population should be managed by one officially recognised breed society. 

The committee recommend that with the exception of deleterious genetically-linked traits, breed societies should maintain the maximum genetic diversity within their breed in line with target 4 of the Kunming-Montreal GBF. If breed societies choose to record subpopulations, they should ensure these are managed properly as part of the breed as a whole, avoiding the creation of sub-groups with a very low effective population size. 

Breed societies may decide to prioritise certain subpopulations within their breed for their own conservation or development programmes, but these should remain the responsibility of the breed society. The creation of subpopulations may more readily serve existing or emerging market niches or help to create a sense of community, but the benefits arising from this would be for the individual keeper or collective breed society rather than be a public good. 

The advice of the committee is that breed societies have a role to play in conserving a wide range of positive traits in their populations and promoting genetic diversity. This is important for conservation breeding programmes, gene banking programmes, or contingency planning for exotic disease outbreaks.

In light of these challenges, the committee recommend that breed societies prioritise collecting and storing germinal products—such as semen and embryos—from these OPs. This precaution would help mitigate the risk of losing valuable genetics in the event of an outbreak of exotic disease. UKGLE are aware that the OP Herefords have already gene banked more than the FAO recommendation of semen from 25 unrelated males, with the Rare Breeds Survival Trust (RBST). UKGLE will consider developing further advice on this issue for UK breed societies.

Listing of original populations on the National Breed Inventory 

In the early years of the inventory, attempts were made to be as inclusive as possible. A large number of breeds, populations and species were listed. Over the years criteria for inclusion have been reviewed by UKGLE and a number have been removed.

In 2020 UKGLE advised that the OPs be merged with their breeds in the published national breed inventory as it was not clear whether the figures for the OPs were included in data supplied for the overall breed population. The committee considered that instances of double counting in data collection of breed numbers would impact on the calculations, for example, to determine the estimated breeding female population or the effective population of the breed. This risked the breed data inaccurately showing a healthier population size and this could impact on the risk status category applied to that breed. This would impact on Defra’s activity to accurately monitor breed population sizes and trends.

The committee considered the frequency and reliability of the data provided for those breeds with OPs. It was noted that in most cases it had not been possible to calculate effective population size (N_e) which is a key measure of genetic health. The N_e values of native breeds feed into the UK’s native breed biodiversity indicator which in turns forms part of the UK government annual report to the CBD. UKGLE advised merging OPs with their main breed to ensure accurate data collection, and so that conservation efforts were directed towards maximising the genetic diversity of the entire breed in line with indicator A4 of target 4 of the Kunming-Montreal GBF.

Committee recommendations on listing original populations

Following the merger of OPs with their main breeds in the UK National Breed Inventory, OPs were subsequently merged on the BAR list. Thus, merging OPs with the main breeds on the NBAR list aligns with UKGLE’s advice to pursue a maximum diversity approach, as recommended by the FAO, to capture as much genetic diversity as possible with the available resources. The committee advise against creating subpopulations with very low N_e due to potential animal health and welfare issues stemming from increased inbreeding.

Genetic drift is recognised as an issue in small populations, where random fluctuations in allele frequencies can lead to the loss of genetic diversity over time. This is particularly problematic for breeds that are already classified as ‘at risk’, as small population sizes increase the likelihood of inbreeding and the manifestation of harmful genetic traits (Allendorf, F.W. and others, 2022). The committee recommend reducing the likelihood of genetic drift by advising against creating subpopulations.

3.3 UKGLE recommendations for conservation

UKGLE recommend that Defra considers activity which is targeted towards limiting the potential for a native breed to become extinct. The committee’s recommendation to merge OPs with their breed on the ‘at risk’ lists is based on this principle. This approach helps ensure that conservation resources are allocated effectively, directed to those whole breeds most at risk, and maximises the impact on overall genetic diversity.

Resources available for native breeds either as agri-environment scheme payments or, for example, during an outbreak of exotic disease should be focussed on breeds that are classified as ‘at risk’.

4. Recommendation for determining ‘at risk’ status of native breeds

4.1 Rationale for updating thresholds

The current NBAR thresholds, originally set under the EU Common Agriculture Policy (CAP) to support land management schemes, have been in place for over 20 years and are considered no longer fit for purpose. The evolving landscape of genetic conservation, as well as the need to focus support on those breeds most at risk, means these thresholds are less effective at directing resources where they are needed most. UKGLE considers that the current thresholds are too high and do not direct limited resources to those breeds most at risk.

4.2 Aligning with international and FAO standards

Strategic priority 2 of the 2007 Global Plan of Action is to develop international technical standards and protocols for characterisation, inventory, and monitoring of trends and associated risks. It specifically states that cross-national inter-comparability of data is essential to be able to monitor trends in, and risks to, animal genetic resources at regional and global levels.

The advice to align the ‘at risk’ list thresholds with international FAO guidelines is based on several factors. The FAO operates on a global level, with input from a diverse range of countries involved in UN conventions, including nations such as Argentina, Australia, and New Zealand. These countries, as well as the USA, with their extensive genetic resources, often incorporate genetic material from traditional European breeds, reflecting the global exchange of breeding stock.

The FAO standards are widely accepted internationally and are considered best practice, offering a comprehensive approach to genetic resource management that reflects global trends in biodiversity. Countries that have adopted FAO guidelines such as Brazil, Australia and Germany benefit from shared international expertise and the ability to benchmark their conservation strategies against global protocols. These FAO programmes are designed to safeguard biodiversity, including livestock genetic diversity, which is critical for sustainable agriculture.

UKGLE recommend that the current thresholds of 7,500 head for cattle, 10,000 for sheep and goats, 5,000 for equines, 15,000 for pigs and 25,000 for poultry on the NBAR list, be updated to the FAO thresholds (FAO, 2013, see chapter 2 – pages 44 to 46 for thresholds). This should help ensure that breeds which are at the greatest risk of extinction are supported. Currently thresholds are based on the estimated number of breeding females. Consideration should also be given to reviewing the risk parameters used to determine the risk status of UK native breeds.

4.3 Benefits of aligning thresholds

Utilising the FAO thresholds enables the UK to align to internationally recognised metrics. It ensures that the data submitted to the FAO’s Domestic Animal Diversity System (DAD-IS) are consistent with global reporting frameworks. This enables global comparisons and enhances international collaboration on conservation strategies. This alignment helps support decision-making through access to global data and strengthens the UK’s contribution to global biodiversity conservation efforts.

The thresholds used in the Defra BAR List, introduced in 2005 to determine eligibility for potential derogation from culling in the event of an outbreak of exotic disease, are already based on FAO risk criteria thresholds. Amending the thresholds will align the 2 ‘at risk’ lists, thereby removing ambiguity and ensuring consistency across the support provided to breeds at risk. The UK’s native breed conservation policy will also be more aligned with global best practices and will enable more focused and effective support for those native breeds at most risk, ensuring long-term genetic diversity and conservation in the UK.

To ensure that the integrity of the national breed inventory is maintained and that breeds are in the correct risk status category, the committee recommend that Defra should obtain full annual data from all native breeds listed on the ‘at risk’ lists. This includes female registrations, male registrations, number of dams, number of sires and number of herds or flocks. These data help to monitor population trends of native breeds and provide more information about the genetic health of breeds that are near the ‘at risk’ threshold.

Trends in populations should be monitored and breeds added or moved between the risk categories as required based on the results of the annual inventory. In line with current practice, if a breed population goes over the threshold limit, Defra should monitor the trend for 3 years to ensure the breed remains over that threshold before considering changing the breed’s risk status on the ‘at risk’ lists.

5. Recommendation for protection of heritage semi-feral populations

5.1 Rationale for recognising semi-feral populations

Recognising heritage semi-feral populations contributes to the UK’s international commitments on the conservation of genetic resources. These populations represent a unique aspect of the UK’s biodiversity, preserving not only genetic diversity but also cultural and historical links to the regions where they originated. Semi-feral populations have evolved in natural environments with minimal handling or interference. 

The importance of recognising semi-feral populations lies in their ability to retain certain ancestral traits that may have been lost in more intensively managed breeds. These populations are uniquely adapted to local environments, possessing genetic traits which are invaluable for biodiversity and genetic conservation, as highlighted in this publication on the role of native ponies in conservation management.  

The UKGLE Committee recommend that recognised heritage semi-feral populations are included on the ‘at risk’ list. This helps ensure their protection for future generations, aligning with both national conservation priorities and international commitments.

5.2 Criteria for inclusion on the ‘at risk’ list

UKGLE have drafted and published the criteria for defining heritage semi-feral or feral populations.

These tests are designed to differentiate heritage semi-feral or feral populations from managed populations or subpopulations within a breed:

1. Lack of routine handling

The population must not be subject to routine human handling. This criterion ensures that these animals have developed independently, with minimal human influence, preserving their natural behaviour and adaptations. 

2. Feral parentage

More than 90% of the population must have been born to feral parents over at least two generations. This confirms the population’s long-standing independence and resilience in a natural environment. 

3. Cultural and historical significance

The population must have a demonstrated historical and cultural connection to the region. This aspect acknowledges the role these animals have played in the cultural heritage of the area and the significance of maintaining this link.

5.3 Difference between heritage semi-feral populations and original subpopulations

While some OPs within managed breeds may also claim historical significance, semi-feral populations differ fundamentally due to their independence from human control. OPs are often still subject to human breeding programmes and management practices, while semi-feral populations display unique behavioural and physiological adaptations that differentiate them from fully domesticated livestock. For instance, they may develop stronger survival instincts, enhanced foraging skills, and greater resistance to local diseases. These traits enable them to thrive in challenging environments where domesticated animals might struggle. 

Unlike OPs, which are often part of a broader breeding strategy within a breed society, semi-feral populations are largely unmanaged and often linked to specific geographic regions. As a result, they are at greater risk of being lost if not recognised and conserved, due to their lower visibility and the challenges of management. Their cultural significance and genetic uniqueness justify their inclusion on the list.

Recognising heritage semi-feral populations in UK conservation policy and their inclusion on the list is a necessary step for the conservation of the UK’s genetic resources. These populations are distinct and conserving them will also help maintain traditional practices that have historical significance. While there are challenges in managing semi-feral populations, they are a critical component of the UK’s biodiversity. Their inclusion on the list helps ensure their protection for future generations, aligning with both national conservation priorities and international commitments.

6. Conclusion

The UKGLE advice underscores the need for a cohesive and scientifically informed approach to native breed conservation in the UK. The key recommendations are summarised below.

1. Whole-breed conservation

The UKGLE Committee recognises the importance of genetic diversity within breeds. UKGLE recommend that UK government prioritise support at breed level and, recognising the context of limited government funds for native breed conservation, that the whole breed should be the focus of conservation support rather than subsets of breeds such as OPs.

The committee recommends adopting a whole-breed conservation approach, preserving genetic diversity and the integrity of entire breeds.

2. Merging of original populations

UKGLE recommend that Defra considers activity which is targeted towards limiting the potential for a native breed to become extinct. The committee advise that the government should follow the recommendations of the FAO, establishing the base unit for conservation policy as the whole breed.

UKGLE advise that it is a matter for individual breed societies to decide whether they wish to register separate subpopulations based on differences in phenotypes within their breeding book. The committee recommend that with the exception of deleterious genetically linked traits, breed societies should maintain the maximum genetic diversity within their breed in line with target 4 of the Kunming-Montreal GBF. The committee advise that breed societies have a role to play in conserving a wide range of positive traits in their populations and promoting genetic diversity.

The committee recommend that breed societies prioritise collecting and storing germinal products – such as semen and embryos – from OPs. UKGLE will consider developing further advice on this for UK breed societies.

The committee advise against creating subpopulations with very low N_e due to potential animal health and welfare issues stemming from increased inbreeding. The committee recommend reducing the likelihood of genetic drift by advising against creating subpopulations.

The committee recommends that in line with Zootech Legislation the entire population of a breed should be managed by one officially recognised breed society. Breed societies have a key role to play in the conservation of breeds, including any subpopulations. Breed societies are encouraged to maintain comprehensive genetic diversity throughout the breed, managing any recorded subpopulations effectively to prevent low effective population sizes. Any benefits arising from creating or maintaining original populations are considered to be for breed societies and individual keepers and not a public good.

3. Determination of ‘at risk’ breeds

The committee recommend that Defra should obtain full annual data from all native breeds listed on the ‘at risk’ lists.

UKGLE recommend that the current thresholds of 7,500 head for cattle, 10,000 for sheep and goats, 5,000 for equines, 15,000 for pigs and 25,000 for poultry on the NBAR list, be updated to the FAO thresholds.

Consideration should also be given to reviewing the risk parameters used to determine the risk status of UK native breeds.

Aligning UK native breed conservation strategies based on population thresholds with international standards, as set out in the FAO guidelines, is recommended to enhance conservation efforts and facilitate better integration into global conservation initiatives.

4. The protection of heritage semi-feral populations

The UKGLE Committee recommend that recognised heritage semi-feral populations are included on the ‘at risk’ list. These populations represent a unique aspect of the UK’s biodiversity, preserving not only unique and beneficial genetic traits, but also cultural and historical links to the regions where they originated.

By focusing on whole breed populations, aligning with international guidelines, and recognising the importance of both managed breeds and semi-feral populations, we aim to enhance the long-term sustainability and genetic diversity of our native breeds. These recommendations are focussed to ensure that conservation efforts are effective, targeted, and capable of addressing the challenges facing the UK’s genetic resources both now and in the future. Through these measures, the committee seeks to ensure that the UK complies with international agreements to which it is a signatory and works towards achieving internationally agreed conservation targets that will safeguard the invaluable heritage of native breeds for future generations.

Glossary

Alleles

An allele is one of 2 or more versions of DNA sequence (a single base or a segment of bases) at a given genomic location on a single strand of DNA. 

Effective Population Size (N_e)

Effective Population Size (N_e) is calculated for each breed in the UK National Breed Inventory using Sewell Wright’s formula (Wright S., 1931):

N_e = 4 x (No. sires x No. dams) / (No. sires + No. dams)

Gene pool

The total collection of genetic material present in a population or species, this encompasses all the different alleles (gene variants) found within that population. 

Genetic drift

Variation changes in the relative frequency of different genotypes over generations in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce. 

References

Allendorf, F.W., Funk, W.C., Aitken, S.N., Byrne, M., & Luikart, G. (2022). Small Populations and Genetic Drift. In Conservation and the Genomics of Populations (2nd ed., pp. 113 to 132). Oxford University Press.

Boes, J., Boettcher, P. & Honkatukia,, M., (eds. 2023). Innovations in cryoconservation of animal genetic resources – Practical guide. FAO Animal Production and Health Guidelines, No. 33. Rome. (pp. 4 to 5; 8 to 12).

Convention on Biological Diversity. (2022). Kunming-Montreal Global Diversity Framework. Agreed at COP15.

Defra. (2002). UK Country Report on Farm Animal Genetic Resources.

Defra. (2006). UK National Action Plan on Farm Animal Genetic Resources.

FAO. (2007). Global Plan of Action for Animal Genetic Resources and the Interlaken Declaration. International Technical Conference on Animal Genetic Resources. Rome.

FAO. (2007). The unit of conservation. In The state of the world’s animal genetic resources for food and agriculture (pp. 448 to 449). Food and Agriculture Organization of the United Nations.

FAO. (2012). Phenotypic characterization of animal genetic resources. FAO Animal Production and Health Guidelines. No. 11. Rome.

FAO. (2013). In vivo conservation of animal genetic resources. FAO Animal Production and Health Guidelines. No. 14. Rome.

Fraser M.D., Stanley C.R., Hegarty M.J. (2019). Recognising the potential role of native ponies in conservation management. Biological Conservation. Volume 235 (pp. 112 to 118). Elsevier.

Regulation (EU) 2016/1012, as substituted and amended by The Animal Breeding (Amendment) (EU Exit) Regulations 2019 and The Animals, Aquatic Animal Health, Invasive Alien Species, Plant Propagating Material and Seeds (Amendment) (EU Exit) Regulations 2020.

Secretariat of the Convention on Biological Diversity. (2010). Aichi biodiversity targets: Strategic plan for biodiversity. 2011-2020. Montreal.

United Nations. (1992). Text of the convention on biological diversity. UN, Rio de Janeiro.

United Nations. (2015). Transforming Our World: The 2030 Agenda for Sustainable Development.

Wright S. (1931) Evolution in Mendelian populations. Genetics. 16:97-159.