Sourced from research undertaken by Philip Davy

At the end of the 2nd World War, there were only 4 registered Exmoor Pony stallions left - all of which have descendants living today. In total there, were only about 50 ponies - a very sorry state of affairs. The enormous task of saving the breed was all in the hands of a small, but dedicated, group of breeders, whose main concern was preserving and developing the breed in its pure form, without jeopardising quality or type.

Despite the temptation to introduce outside blood from other breeds, the breeders stayed true to the pure Exmoor and, over the next 30 years, carefully established 44 mare lines. Since the 1970s, these 44 mare lines have reduced to 29 mare lines, with vital mitochondria lost from 15 mare lines. This represents one third of the Exmoor pony gene pool, which can never be expanded once lost. It is therefore important that all Exmoor pony owners today, whether breeders or not, understand the importance of this small, but critical gene pool and have some understanding of the bloodlines. More than once, a mare owner has realised that they own the last mare in a rare bloodline and have sought advice and bred a pure Exmoor foal from that mare to continue that particular line.

Meiosis and the Importance of Sex Specific Inheritance
Philip Davy has has been studying Exmoor pony genetics and has recently produced material to explain some important basic genetic information that makes it easier to understand the key elements that affect Exmoor pony breeding.

The Structure of a Pony
Within cells, the nucleus contains DNA, which carries information that decides the pony's genetic make-up. It is stored in chromosomes. There are 32 chromosomal pairs in a mature pony cell, including one pair that determines the sex of the pony.

DNA, Genes and Alleles
The gene contains a short section of DNA that codes for the production of a protein. Different versions of the same gene are called alleles. The expression of alleles is controlled by regulatory factors - but importantly, they are also influenced by the environment. Different versions of a gene are called alleles. Each pony has a different combination of alleles, which makes each pony unique.

One cell = 4 gametes. Gametes contain a random mixing of DNA and a (future) pony gets half of the gametes from each parent. Cells continue to divide in two, through the process of Meiosis, then four gametes - and eventually they become a foal.

Sex Specific Inheritance
Mitochondrial genes are only passed on by mares. The Y chromosome is only present in males. Mitochondria have their own DNA, which the mare passes to the foal. When the egg is fertilised during conception, the back part of the sperm which contains the male mitochondria drops off and doesn't enter the egg - hence only the female mitochondria continues through the offspring.

So, in breeding, it is essential to consider both the stallion and mare lines. Variation in breeding lines allows for a healthy evolution of the pony. With such a small gene pool, it is important to preserve and protect the rare and little used bloodlines, so that they may, in turn, allow important alleles (and possible hidden recessive alleles - which could contain attractive and desired characteristics that may not be obvious in that particular pony) to return to the breed, instead of being lost forever, leaving too small and restricted a gene pool. A varied type of breeding population determines the breed's survival. The more ponies that can be bred from, the better.

Today, there are distinct herds of Exmoor ponies, established and new stallions, and 29 mare lines in existence. Taking time to understand the significance of these bloodlines bloodlines - popular and rare - is important in making the most of the available gene pool, for the continued health and prosperity of the Exmoor pony breed..

If you would like to find out more about the Exmoor pony bloodlines, trace the pedigree of your Exmoor mare or gelding or take advice on the best stallion to select, please contact the Exmoor Pony Society, who will be delighted to help you. www.exmoorponysociety.org.uk.