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Name: Dr Tim Bray
Organisation: Bristol Zoo Gardens (UK zoological collection: www.bristolzoo.org.uk)
Role: Lecturer in Conservation Science
Nationality and main countries worked: British; worked in: UK, South Africa, Saudi Arabia, Czech Republic)
Why is captive breeding important in applied ecology?
There are many reasons why captive breeding programmes exist. Zoological collections, and other ex-situ initiatives, have to breed animals or propagate plants in order for that collection to be self-sustaining. That is important as captive collections have an important role in enthusing and educating people, and thus in conservation and ecology more widely. More importantly, captive breeding programmes are often necessary for the survival of entire species or subspecies. In some cases, they might form of “ark” for a species that is extinct in the wild. Alternatively, captive breeding can provide a supply of individuals to be released into the wild to either bolster wild populations through the process of supplementation or to reintroduce a species extirpated from an area. This is especially important for species classified as Threatened by the IUCN or for species with an important ecological function by virtue of being a keystone species or ecosystem engineer.
What is your day-to-day job?
I work in the Conservation Science team at Bristol zoo, which is diverse in its activities. There is a focus on the organisational and lecturing aspects of the job and participation on student excursions to anywhere from Dartmoor to Madagascar. We also supervise everything from sandwich placements to PhD students; it was great to get some camera traps up for a third-year BSc project on wallaby activity patterns in the zoo this year, for example. Then there is the project participation with other departments and institutions, which recently has included work on amphibian probiotics and reptile molecular marker development for assessing breeding programmes and lineage origins. We also have a variety of commitments within our team that have to be covered when necessary, such as updating the primate assessments on the IUCN Red List. To round things off we have our own research interests, I quite fancy tweaking my mammal-based research portfolio into the direction of the reptile house and am currently developing this as other projects are finishing up.
The zoo is involved in devising and running captive breeding programmes. Can you explain a bit more about how these work?
Captive breeding programmes are usually part of a broader European Endangered Species Programme, which considers all aspects of conservation for that species. One of the first and most important considerations is ensuring that there are enough individuals in the captive population, particularly initially. If you start off with only ten founder individuals then all future generations are based the gene pool of those ten individuals. More individuals usually means a bigger initial gene pool, although this is not always the case as founder individuals can be inbred or closely related so that having larger numbers of animals does not always guarantee a larger the gene pool.
After a captive population has been founded, it is important to make sure that captive breeding is optimised to maintain as much genetic diversity over time as possible. There are two main considerations here. The first is the size of the population: small populations are more prone to genetic drift whereas large populations are generally more stable. In larger populations the random changes in allele frequency that occur are less likely to result in fixation or loss of allelic diversity. The second consideration is avoiding inbreeding by allowing, and if necessary encouraging, matings between individuals that are not close kin. This usually requires there to be an artificial metapopulation with regular movement of some individuals (gene-flow) between different captive collections to maintain a diverse gene pool and minimise population isolation. To manage the breeding dynamics and maintain a successful captive breeding population it is therefore essential to have records of parentage. Keeping a studbook is one way to ensure that the genetic relatedness of each individual is known. In this way genetic diversity is maintained as far as possible by avoiding pairing individuals that are closely related wherever possible.
What is your most interesting recent project and why?
I have recently been involved with the World Pheasant Association, which is embracing new genetic approaches to looking into conserving species. One potential problem is that of hybridisation in captivity. This can be particularly important in cases where the species is no longer found in the wild and where there are very small breeding populations. Using genetic methods we produced reference data to assess whether individuals not currently in studbooks are appropriate for inclusion in breeding programmes.
I haven’t been working in a zoo environment very long but already I am seeing what can (and needs to) be done in wildlife molecular genetics for breeding, identification, and uncovering geographical origins of organisms. I have been peripherally involved in a great project on this with the African pancake tortoise Malacochersus tornieri to improve the way that individuals are added to breeding programmes when we have little or no prior information on their provenance: individuals that have been confiscated at airports, for example. Genetic tools are a perfect way of doing this. This is particularly relevant right now with the European Commission launching its Action Plan to ‘crack down on wildlife trafficking’.
What do you see as the main challenges in your field and how can they be overcome?
Well, you first of all have the problem of defining species. This is obviously critically important when you are managing a species-specific captive breeding programme and can be much harder than it sounds, especially when individuals of different species look very similar to one another. Understanding hybridisation is challenging too. Ideally you want to manage captive breeding so that there is no hybridisation between species or subspecies. However, in some cases, there are very few genetically “pure” individuals and it might be better to have some individuals that are hybrids, or have hybrid lineages, rather than having too few founder individuals in the breeding populations. Sometimes it might even be important to deliberately hybridise, or at least mix sub-species or breeds deliberately, in order to breed out undesirable genetic characteristics. Adaptively unfavourable traits can become fixed in populations due to extended periods of small population size, an example being that of tail-kinks in African cheetah. Once a captive breeding programme is set up, one of the big challenges is the cost of moving animals between collections and the amount of paperwork necessary to do so in order to comply with legislation.
There are also problems resulting from the success of breeding programmes. Sometimes particular pairs are really good at breeding and produce lots of young. This might sound fantastic but actually you don’t want offspring of specific individuals to become too numerous and for the genes of those individuals to become overrepresented in the population. There can also be the issue of what to do with any surplus animals, especially if reintroduction is complicated or not possible because the original threats have not been resolved. Space and resources are finite so this can be a real issue.
What’s the most satisfying part of your work?
It might sound odd, given that I work in a zoo, but the most satisfying part of this role is the in-situ aspect! A lot of the captive breeding work is done to supplement wild populations or reintroduce species, or at least to keep a viable species alive to allow reintroduction in the future if/when in-situ problems have been resolved. Aside from these direct links, a good proportion of all revenue from people coming to visit Bristol Zoo is spent on in-situ conservation initiatives. For example, we work on an in-situ project in South Africa on African penguins. This species is very site-faithful and birds use the same breeding colonies year after year. This is usually an advantage but fish stocks are declining globally and the distribution of good feeding areas is changing. Breeding success is decreasing massively in some colonies due to chick starvation as parents have to hunt for longer to find food. We work to collect chicks at the end of the season when parents cannot raise them or have abandoned them, and hand-rear them. Between 2006 and 2014, almost 4,000 chicks were rescued to be hand-reared and, of these, 77% were released back into the wild. We also undertake behavioural research on our own captive penguins to help inform in-situ conservation strategies.
Finally, how did you get into conservation ecology and what advice would you give to others?
My research career seemed to be moving away from conservation and I felt it becoming increasingly academic. I love the variety of amazing directions you can go with your research work but I realised this disconnection with the practical side of biology was not what I wanted. I began to apply to more on-the-ground and conservation focussed entities and was fortunate enough to join the Bristol Zoo team. Keep your eyes open for opportunities and make yourself available to help out on projects and give presentations, it may take years of applications and making the right connections (as it did in my case) but it is worth it to avoid compromising what you want to do.