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Wild Animal Breeding

Effective Population size and its concept in wild animal breeding

Concept was given by Sewall Wright
Population size is extremely important when we are evaluating conservation priorities for a breed or species.
In small closed population all the individuals eventually become related by descent (Inbreeding).
How quickly they become related depends on the effective population size.
ØH-W law holds true only when population size is infinitely large.
Finite population size results in inbreeding and loss of genetic variation.
A population bottleneck is a sharp reduction in the size of a population due to human interventions.
By understanding effective population sizes, we can predict how quickly a population of animals will lose genetic variation, and come at brim extinction.
Inbreeding is the most common phenomena in domestic as well as wild animals (Small size, and it has resulted in deleterious effects and loss of fitness of the population due to recombination between undesirable genes (recessive lethals).
The effective population size is the size of an ideal population (follow HW law) that would lose heterozygosity at a rate equal to that of the observed population.
Effective population size is the number of individuals that would give rise to the calculated sampling variance or rate of inbreeding, if they bred in manner of idealized population.
Effective population size is almost all the time smaller than the real or census population size

Method for estimation

Estimating the appropriate effective population size is crucial in conservation biology;

A conservative rule of thumb used by some biologists is that Ne is usually about one-fifth of the total population size

When the sex ratio of a population varies from the Fisherian 1:1 ratio, effective population size is given by:

How much should be N_e ?

Frankline (1980) suggested that if Ne > 50 leads to short term survival (avoid inbreeding )
If Ne > 500 needed for long term survival (ability to evolve in changing environments)
A genetically effective population size of at least 50 individuals is necessary for conservation of genetic diversity in the short term and to avoid inbreeding depression
A Ne of 500 is needed to avoid serious genetic drift in long term

Controlled Breeding and Assisted reproduction of wild animals

Wildlife populations

In situ: free-roaming wild animals in their natural habitat, reproducing more or less undisturbed

Ex situ: Wildlife held outside its natural habitats, in a restricted area, and usually with reproduction controlled by selection of breeding partners

Since, true wild habitats are gradually disappearing, true in situ populations are also vanishing.
Now, natural environments converted into managed reserves, resulting inevitable human influence even in natural surroundings.
According to the International Union for Conservation of Nature (IUCN) guidelines, conservation in the wild is the ultimate objective

Controlled Breeding Programme

Several examples exist, however, in which animals became extinct in the wild, and could only be re-established after Controlled Breeding Programmes (CBPs) were employed
Integrating and advancing proactive wildlife reproduction management, using scientific tools and technologies, is an essential step for sustainable wildlife breeding and conservation
To overcome the logistical problem of segregated populations, assisted reproductive techniques (ART), such as artificial insemination (AI) or embryo transfer (MOET), could help to exchange genetics, but also to have ex situ preserved genes transferred back into the natural environment, without the risks associated with the re-introduction of an individual animal raised under unnatural conditions.
A CPB can be accommodated within or outside the natural range of the species.
Outside the natural range, CBP’s are mainly established in zoological facilities which is needed because of habitat loss, political and economical instability of a country, and to educate the general public;
But the challenges are costs, space, resources, lack of genetic diversity of founder populations and regulatory barriers
Another option is to establish intensively managed breeding stations within, or close, to the natural habitat site. Such set-ups have helped a number of conservation breeding and reintroduction programmes
Improved husbandry and stringent exchange of breeding bulls have resulted in a self sustaining Asian elephant population in European zoos

CBPs : Bottlenecks

It is very much possible to establish CBP ex situ. The advancement in assisted reproduction technology may now connect the different genotypes, may offer solution to lack of diversity.
In reality, live offspring have been produced following AI or ET in only around 50-60 wildlife species. A first-time success is reported in many cases, but subsequent regular applications are not
The sophisticated biotechnology are still forceful, when a species is close to extinction, it is basically too late to establish reasonable and repeatable methods for assisted reproduction.
Because, a holistic and science-based approach towards ART applications requires a minimum number of individuals of a species and time.
ART is only applicable in conservation of a particular species, if it has been studied in that or a closely related species.
On top of this, most funding is available for in situ conservation compared to ex situ breeding and ART research.

CBPs : Success

Successful collection and cryopreservation of semen from Asian and African elephants, Javan rhino and in giraffes has led to the successful AI using fresh and frozen-thawed semen in Asian and African elephants
These success can now be applied, firstly in genetic exchange to support isolated populations; and secondly Genetic Resource Bio-banking
By shipping cryopreserved semen samples, in situ and ex situ populations can be connected in both directions and separations by country and continents can be bridged.

CBPs : Future

Viable semen bank may be established to enrich any isolated population in the future.
Other technologies, such as sex-sort spermatozoa, will be needed in the future for efficient wildlife breeding. This has been demonstrated for Asian and African elephants, Southern white rhino, black and Indian rhino.
Achievement of higher numbers of female births after AI with sex-sorted semen would boost enormously the sustainability of breeding programmes with long-lived animals, such as elephant and rhino.

Projects : Wild Animals

India is one of the 17 mega diversities in the world and is home to 7.6% of all mammal, 12.6% of bird, 6.2% of reptile, and 6.0% of flowering plant species.
Keeping in view the human encroachment, the GOI did take effective initiatives to conserve wildlife in the country, and amongst it, most commendable initiatives is the Wildlife Protection Act of 1972, which prohibits trade of rare and endangered species.

Project Tiger

Project Tiger was initiated as a Central Sector scheme in 1973.
Many tiger reserves were started and tiger conservation was aimed in these.
Project Tiger has seen significant success in recovery of the habitat and increase in the population of the tigers in the reserve areas, from a scanty 268 in 9 reserves in 1972 to above 1000 in 28 reserves in 2006 to 2000+ tigers in 2016.

Project Lion

In 1972, this project was initiated in India.

Steps taken were,

Shifting of all Maldharis and their resettlement
Construction of barricades along the water resources to prevent entry of cattle.
Fencing of Gir sanctuary by dry rubble wall.
Minimizing of human interferences.
Securing of full co-operation of legistlators, public and maldharis.
Improving the habitat of lions in Gir region.

Project Elephant

The project was started officially in 1991-92 but launched in 1993 withy objectives:

To identify the limiting factors of the habitat and to remove it by the management.
To adapt systematic management plans.

Project Crocodile

From 1st April, 1975, the actual project was started with the following objectivities:

To continue the task of locating best crocodile areas within the country.
To collect eggs as soon as possible after laying and transport them to central protection area for hatchery incubation and to rear the young one until it assumes size for release back into the wild.

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