The Designation & Management of Threatened Species: is there any point?

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The management of threatened species is an important practical way in which conservationists can intervene with extinction process and reduce the loss of biodiversity by ensuring some (high) probability of long-term species survival (Young, 1994; Norris, 2004). Though maintaining the whole ecosystem is often the target of conservationists, if a population is severely threatened this may not be sufficient. A more direct population management may be required (Hunter, 1996). To conserve such rare species there is a critical need to assess the impacts of threats on the long term survival of an individual population. This requires detailed information about the biology of the species concerned, the habitat it prefers, and the factors that might affect both of these (Root, 1998). Natural resource agencies worldwide develop species recovery plans that specify threats, propose targets required for recovery, and evaluate the extent to which habitat alteration and restoration may influence species decline and recovery (Good et al. 2003)

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  • Secondary Extinctions – e.g. Hibiscadelphus – a genus of plants endemic to Hawaii. Three of the seven species of Hibiscadelphus are extinct and all of the remainder are either extinct in the wild or extremely rare. It has been suggested that this may be due to poor pollination as a result of the extinction of their honeycreeper.
  • Threatened species lists have been used to: (1) set priorities for resource allocation for species recovery, (2) to inform reserve system design (3) to constrain development & exploitation, and (4) to report on the state of the environment. Each time a species goes extinct the independent evolutionary history embodied in that lineage is lost forever.
  • Madsen et al. (1999) restored a severely inbred adder population by restocking from an allopatric large and genetically variable adder population.
  • What is the point in managing threatened species? Aren’t these species eventually doomed? Reduced fitness due to loss of genetic diversity (genetic drift & inbreeding) & is the species able to adapt to environmental change?
  • The population size at any given time is a function of both the population size at the previous time step and the values drawn at random from distributions of numbers described by the model’s parameters.
  • Caro and Luarenson (1994) argue that genetic considerations are clearly important in the management of captive populations but may only be relevant to free-living populations in limited circumstances because they impact on a slower time scale than environmental or demographic stochasticities. Nevertheless if one considers only genetic stochasticities for endangered species, an effective size of at least 500 and actual numbers of adult census size of at least 5000 (Ne/N = 0.1 for wild populations) are required for maintaining long term genetic diversity and minimising inbreeding depression.
  • However, this cross-fostering programme involved translocation to South East Island (12 km away) coupled with interspecific cross-fostering, then about two weeks after hatching, translocation back with further intraspecific cross-fostering to avoid imprinting in the wrong species. The robin recovery programme is an example where species-driven management has facilitated effective ecological conservation and recovery. Also it has increased support for biological conservation and appreciation of biological values, with Chatham Islanders now actively involved at all levels in local conservation issues and projects
  • Besides being one of the few “extinct” animals to be rediscovered, the midwife toad is unusual because of the way it reproduces. Native only to Mallorca, A. muletensis spawns in the water, but once the female has produced her string of pearl-like eggs, the male carries around his hind legs, keeping them moist and at the correct temperature until they hatch (hence the name midwife). When they are ready to hatch, he releases the larvae into a suitable body of water where they remain as tadpoles for as long as a year.
  • The Designation & Management of Threatened Species: is there any point?

    1. 1. The Designation and Management of Threatened Species ... is there any point? Mario V. Balzan 26 th March 2007 Nesoenas mayeri EN B1ab(iii) Loxodonta africana VU A2a Ursus maritimus VU A3c University of Malta Conservation & Management of Natural Resources
    2. 2. Outline <ul><ul><li>Introduction </li></ul></ul><ul><ul><li>Conservation Biology of Threatened Species </li></ul></ul><ul><ul><li>Threatened Species Designation </li></ul></ul><ul><ul><ul><li>The IUCN Red List </li></ul></ul></ul><ul><ul><ul><li>Regional Assessments </li></ul></ul></ul><ul><ul><li>The Status of Globally Threatened Species </li></ul></ul><ul><ul><li>Setting Conservation Priorities </li></ul></ul><ul><ul><li>Management Interventions </li></ul></ul><ul><ul><li>Is there any point? </li></ul></ul><ul><ul><li>Case Studies </li></ul></ul><ul><ul><li>Conclusion </li></ul></ul>
    3. 3. Introduction Conserving Biodiversity <ul><ul><li>Conservation biology has a value-laden objective: to conserve genetic variants, biological species, communities and ecosystems because they are considered to represent various forms of utilitarian, intrinsic and extrinsic values (Lande 1988, Tufto et al. 1999). </li></ul></ul><ul><ul><li>Research shows an accelerating decay of contemporary biodiversity, as a direct and indirect consequence of human actions. </li></ul></ul><ul><ul><li>Along with the degradation of ecosystems worldwide, thousands of species and even more genetic variants are being lost (Kapoor-Vijay, 1992; Ceballos et al. 2005). </li></ul></ul><ul><ul><li>Conservation has thus become an urgent task for both governments and the public (Zhang et al. 2002) as many species now require benign human intervention to improve and to ensure their survival (Frankham, 2003). </li></ul></ul>
    4. 4. Conservation Biology of Threatened Species <ul><ul><li>Though maintaining the whole ecosystem is often the target of conservationists, if a population is severely threatened this may not be sufficient and a more direct population management may be required (Hunter, 1996). </li></ul></ul><ul><ul><li>The management of threatened species is an important practical way in which conservationists can intervene with extinction process and reduce the loss of biodiversity by ensuring some (high) probability of long-term species survival (Young, 1994; Norris, 2004). </li></ul></ul><ul><ul><li>In his seminal work, Caughley (1994) argues that two paradigms exist for understanding extinctions of populations, the small population paradigm & the declining population paradigm </li></ul></ul><ul><ul><li>The small population paradigm emphasizes factors threatening populations when they become small, while the declining population paradigm emphasizes the process and factors for populations’ decline in the first place. </li></ul></ul>
    5. 5. Small Population & Declining Population Paradigms Both paradigms are important and need to be taken into account when assessing endangerment and designing recovery plans for threatened species Strong basis in problem solving Weak link to actuality Weak theory “rooted in empiricism” Strong theory From wildlife management From genetics & population ecology Traditional Developed in 1980s Extinction due to external factors (e.g. habitat loss) Extinction due to low numbers Declining Population Paradigm Small Population Paradigm
    6. 6. Declining Populations <ul><ul><li>Life-history and behavioural strategies in a population are the outcome of evolutionary processes that depend on fitness of particular strategies under prevailing environmental conditions. </li></ul></ul><ul><ul><li>When humans alter the environment, the fitness of existing strategies may be drastically reduced. </li></ul></ul><ul><ul><li>Four major deterministic (cause-and-effect) sources of decline: </li></ul></ul><ul><ul><ul><li>Overkill </li></ul></ul></ul><ul><ul><ul><li>Habitat destruction and fragmentation </li></ul></ul></ul><ul><ul><ul><li>Impact of introduced species </li></ul></ul></ul><ul><ul><ul><li>Chains of extinctions (secondary extinctions) </li></ul></ul></ul>
    7. 7. Declining Populations <ul><li>In most cases several factors combine to reduce populations to a size where additional stochastic factors become significant. </li></ul>
    8. 8. Small Populations <ul><ul><li>The new ideas emerging in the 1980s were almost without exception within the small population paradigm. </li></ul></ul><ul><ul><li>Shaffer (1981) identified four interacting factors, other than deterministic factors, that might contribute to a population’s extinction. </li></ul></ul><ul><ul><ul><li>Demographic stochasticity – uncertainty due to the random variation in reproductive success & survivorship of a finite number of individuals </li></ul></ul></ul><ul><ul><ul><li>Environmental stochasticity – temporal variation of habitat parameters e.g. climate, nutrients, parasites & diseases. </li></ul></ul></ul><ul><ul><ul><li>Natural catastrophes e.g. droughts, floods, fires which may occur at random intervals through time </li></ul></ul></ul><ul><ul><ul><li>Genetic stochasticity – the random variation in the gene frequencies of a species due to genetic drift, founder effect or inbreeding, which alter the survival and reproductive probabilities of individuals. </li></ul></ul></ul>
    9. 9. Small Populations <ul><li>The combined impact of  deterministic factors  &  stochastic factors  is more damaging than the sum of their individual effects, and often leads to a sequence of positive feedback loops which might drive a species to extinction –  the  extinction vortex . </li></ul>
    10. 10. <ul><ul><li>Historically conservation has focused on charismatic species or major vegetation types (McNeely, 2002). </li></ul></ul><ul><ul><li>With the recognition of values and importance of biodiversity in the Convention on Biological Diversity (CBD) and the adaptation of the ecosystem approach as the primary framework for action under the Convention, biodiversity preservation became a major goal of conservation and species represent the taxonomic level at which biodiversity is usually measured (Hayes, 2006). </li></ul></ul><ul><ul><li>When resources are limited, there is an imperative to rank species according to risks they face. </li></ul></ul>Threatened Species Designation
    11. 11. The IUCN Red List of Threatened Species <ul><ul><li>Since the mid-1960s the IUCN has been producing synoptic lists of threatened species in a series of publications called Red Data Books. </li></ul></ul><ul><ul><li>It aims to provide the general public, conservationists, NGOs, the media, decision makers & policy makers with the most comprehensive scientifically rigorous information on the conservation status of the world’s species, so that informed decisions and actions cam be taken (IUCN, 200 </li></ul></ul>
    12. 12. The IUCN Red List of Threatened Species
    13. 13. The IUCN Red List of Threatened Species <ul><ul><li>Species assessments typically include expert input from one or more ‘assessors’. These assessments are peer reviewed by at least two evaluators assigned by the relevant ‘Red List Authority’ (established for taxonomic groups; typically the corresponding IUCN-SSC Specialist Group). </li></ul></ul><ul><ul><li>Results are checked for consistency among regions and taxa by the Red List Programme Office, and all specialists involved are named (Rodrigues et al. 2006). </li></ul></ul>
    14. 14. <ul><ul><li>The pre-1994 IUCN Red List assessments relied on the experience and common sense of experts, without following a protocol. </li></ul></ul><ul><ul><li>Over the last decade the nature of these assessments has changed dramatically with the utilisation of a range of quantitative criteria developed through wide consultation (Rodrigues et al, 2006). </li></ul></ul><ul><ul><li>The IUCN Red List approach assesses each taxon’s threat status by using one to eight threat categories determined by a review of its conservation status throughout the taxon’s distribution range. </li></ul></ul><ul><ul><li>Three of these categories are Critically Endangered (CR), Endangered (EN) & Vulnerable (VU) , and are collectively known as the Threatened category. </li></ul></ul>The IUCN Red List of Threatened Species
    15. 15. Threatened Species Designation <ul><ul><li>There are five quantitative criteria which are used to determine whether a taxon is threatened or not, and if threatened which category of threat it belongs. </li></ul></ul>Population Reduction A Small Distribution Decline or Fluctuation B Small Population Size & Decline C Very small or restricted population D Quantitative Extinction E Critically Endangered Endangered Quantitative Thresholds Vulnerable
    16. 16. <ul><ul><li>The relevant factor in the IUCN threatened species designation is whether any one criterion is met. </li></ul></ul><ul><ul><li>However, a taxon should be assessed against as many criteria as applicable for a specific category or threat. </li></ul></ul><ul><ul><li>Though based on quantitative thresholds the system remains relatively flexible through the use of inference and projection, to ensure that taxa for which there is very little information can be also assessed. </li></ul></ul>Threatened Species Designation
    17. 17. <ul><ul><li>The relevant factor in the IUCN threatened species designation is whether any one criterion is met. </li></ul></ul><ul><ul><li>However, a taxon should be assessed against as many criteria as applicable for a specific category or threat. </li></ul></ul><ul><ul><li>Though based on quantitative thresholds the system remains relatively flexible through the use of inference and projection, to ensure that taxa for which there is very little information can be also assessed. </li></ul></ul>Threatened Species Designation
    18. 18. Threatened Species Designation Some local & other illustrious examples Helichrysum melitense Common Name: Sempreviva t’Ghawdex Status: CR B1ab(i,ii,iii,iv,v) Cremnophyton lanfrancoi Common Name: Bjanka ta’ l-Irdum Status: CR B1ab(i,ii,iii,iv,v) Delphinus delphis (Mediterranean subpopulation) Common Name: Short-beaked common dolphin Status: EN A2abc Falco naumanni Common Name: Lesser Kestrel Status: VU A2bce+3bce Ursus maritimus Common Name: Polar bear Status: VU A3c Ailuropoda melanoleuca Common Name: Giant Panda Status: EN B1+2c, C2a
    19. 19. Threatened Species Designation Regional Assessments <ul><ul><li>The IUCN Red List Categories and Criteria (2001) were developed for classifying species at high risk of global extinction (IUCN, 2003). </li></ul></ul><ul><ul><li>However, regional and local conservation agencies require threat assessments in order to provide baseline data to allow comprehensive decisions to be made with regard to relevant conservation and management programmes (Keith, 2005). </li></ul></ul><ul><ul><li>Several national and regional red lists, such as Schembri and Sultana (1989) for the Maltese Islands, with different classification criteria were used in the past. </li></ul></ul>
    20. 20. Threatened Species Designation IUCN Regional Assessments <ul><ul><li>Following a resolution adopted during the First World Conservation Congress in Montreal (WCC Res. D. 1.25), a protocol was released ( “Guidelines for application of IUCN Red Data List criteria at regional levels” ) for determining how the global Red List categories and criteria may be applied on a regional scale. </li></ul></ul><ul><ul><li>Extinction risk for an isolated regional (e.g. national) level is identical to that of an endemic taxon, and in these situations the criteria can be used with unaltered thresholds at any geographical scale (Ginsburg, 2001). </li></ul></ul><ul><ul><li>However, a “national population” can often not be considered to be biologically isolated, which makes it difficult to estimate extinction risk for the part of the population within national boundaries (Keller et al. 2005). </li></ul></ul>
    21. 21. Threatened Species Designation IUCN Regional Assessments <ul><ul><li>As a result, regional assessments proposed by IUCN (2003) are characterized by a two-step process: </li></ul></ul><ul><ul><ul><li>A preliminary category is assigned by treating the national population as if it where equivalent to the global population or completely isolated from conspecific populations. </li></ul></ul></ul><ul><ul><ul><li>To what extent the existence and status of any conspecific populations outside the region affect the risk of extinction of the species within the region? </li></ul></ul></ul><ul><ul><li>A species can be “downgraded” or “upgraded” – assigned to a lower or higher category depending on whether populations outside the country are judged to decrease or increase extinction risk of the population within the country. </li></ul></ul>
    22. 22. Threatened Species Designation IUCN Regional Assessments <ul><ul><li>As a result, regional assessments proposed by IUCN (2003) are characterized by a two-step process: </li></ul></ul><ul><ul><ul><li>A preliminary category is assigned by treating the national population as if it where equivalent to the global population or completely isolated from conspecific populations. </li></ul></ul></ul><ul><ul><ul><li>To what extent the existence and status of any conspecific populations outside the region affect the risk of extinction of the species within the region? </li></ul></ul></ul><ul><ul><li>A species can be “downgraded” or “upgraded” – assigned to a lower or higher category depending on whether populations outside the country are judged to decrease or increase extinction risk of the population within the country. </li></ul></ul>
    23. 23. The Status of Globally Threatened Species <ul><ul><li>The 2006 IUCN Red List evaluates the conservation status of 40,168 species and lists 16,118 of them as threatened with a high probability of extinction </li></ul></ul><ul><ul><li>The total number of threatened species is based on the assessment of just about 1% of the world’s 1.6 million described species. </li></ul></ul><ul><ul><li>The situation of several vertebrate (especially reptiles, fish and amphibians), invertebrates and some plant groups seems to be of immediate concern. </li></ul></ul>40% TOTAL 68% Monocotyledons 74% Dicotyledons 34% Gymnosperms 66% Ferns and allies 86% Mosses 85% Crustaceans 45% Molluscs 52% Insects 40% Fishes 31% Amphibians 51% Reptiles 12% Birds 23% Mammals Number threatened in 2006, as % of species evaluated
    24. 24. Setting Conservation Priorities <ul><ul><li>In our present age of extinction we have the potential to decide which species are saved and which are sacrificed – the ‘agony of choice’ (Vane-Wright et al. 1991) </li></ul></ul><ul><ul><li>Though the purpose of threatened species lists is to produce a relative estimate of the likelihood of extinction of a taxon these lists have inevitably become linked to decision making processes. </li></ul></ul><ul><ul><li>However extinction risk should be one of a range of considerations that determine priorities for action of for conservation funding (Mace et al, 2006). </li></ul></ul><ul><ul><li>Setting of conservation priorities and recovery plans for threatened species also needs to take into account other factors such as ecological, phylogenetic, historical, economic or cultural preferences for some taxa over others, as well as the probability of success of conservation actions, availability of funds or personnel to carry out such actions, and legal frameworks for conservation of threatened taxa (IUCN, 2003). </li></ul></ul>
    25. 25. Setting Conservation Priorities
    26. 26. Threatened Species Recovery Plans <ul><ul><li>Threatened species recovery programs have arisen worldwide to combat projected losses of biodiversity. </li></ul></ul><ul><ul><li>In addition to identifying and legally protecting at-risk species, most such efforts provide for threatened species recovery programs which are directed toward increasing the populations of listed species. </li></ul></ul><ul><ul><li>A typical recovery plan consists of: </li></ul></ul><ul><ul><ul><li>a thorough overview of the status of the species, including any relevant scientific data; </li></ul></ul></ul><ul><ul><ul><li>a recovery objective (for example, a target population number), and a list of criteria for indicating when the objective has been achieved; </li></ul></ul></ul><ul><ul><ul><li>an implementation schedule, including priorities of tasks, cost estimates and monitoring strategies; </li></ul></ul></ul>
    27. 27. Threatened Species Recovery Plans <ul><ul><li>The effectiveness of these recovery plans can be improved through the incorporation of dynamic, explicit science in the recovery criteria, such as linking species’ biology to recovery criteria. This ensures that recovery plans are appropriately suited to each species’ situation (Boersma et al. 2001). </li></ul></ul><ul><ul><li>However preponderance of programs strong in natural science research and methods has often impeded the ability of people involved to succeed (Wallace et al. 2004). </li></ul></ul><ul><ul><li>A recovery plan may include a myriad of different options. Such options may include the dedication of protected areas, modification of disturbance regimes like fire and logging, capture of animals for captive breeding, harvesting, reintroduction, monitoring, construction of corridors between existing habitats, research and technical assistance for landowners, and public education (Possingham & Davies, 1995; Kurpis, 2002) </li></ul></ul>
    28. 28. Management Interventions <ul><ul><li>The first objective of threatened species management is to halt decline and increase the size of the populations. This alleviates all of the stochastic threats to the species </li></ul></ul><ul><ul><li>Understanding the causes of population declines is pivotal in designing effective practical management of threatened species (Norris, 2004) </li></ul></ul>
    29. 29. Management Interventions <ul><ul><li>On the other hand, various management strategies have been proposed for threatened populations and species (Maguire et al 1987; Woodruff, 1989) within the small population paradigm </li></ul></ul><ul><ul><li>Caughley (1994) attributes the success of rescue programs to the two paradigms coming together at the right time and the right way. This may serve for almost any troubled species </li></ul></ul>
    30. 30. Management Interventions <ul><ul><li>Management interventions, to conserve populations of threatened species have been broadly classified by Hunter (1996) into three categories: </li></ul></ul><ul><ul><ul><ul><li>Providing resources that may be scarce, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Controlling threats e.g. predators, human impact </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Directly manipulating populations </li></ul></ul></ul></ul>
    31. 31. In Situ Conservation Controlling threats & Providing Resources <ul><ul><li>Assess the need to provide a key missing resource that is a limiting factor. </li></ul></ul><ul><ul><li>Threat control, including overexploitation of natural resources by humans and other interspecific interactions (e.g. with competitors, predators, grazers, parasites or pathogens), to ensure that the species recovers and to maximise the number of genes in the population that can be passed on to the next generation - the effective population size (Ne) . </li></ul></ul><ul><ul><li>While a number of species protection measures have been effective, species are best conserved as parts of larger ecosystem </li></ul></ul>
    32. 32. In Situ Conservation Controlling threats & Providing Resources <ul><ul><li>Protected areas are defined as </li></ul></ul><ul><li>“ areas of land and/or sea especially dedicated to the protection and maintenance of biological diversity, and of natural and associated cultural resources, and managed through legal or other effective mean   (IUCN, 1994) .” </li></ul><ul><ul><li>Existing protected areas make a valuable contribution to species conservation worldwide, with many species now restricted to protected areas, having lost their habitat elsewhere. </li></ul></ul><ul><ul><li>Case-study: In south-eastern US red-cockaded woodpeckers Picoides borealis , classified as vulnerable C1+2a(i), are threatened by severe exploitation of its habitat - particularly the old, dying longleaf and loblolly pines that it uses for nesting. Consequently, one can preserve the woodpecker only by maintaining the sort of ecosystem which it requires through the setting up of protected areas (Soulé & Simberloff, 1986) </li></ul></ul>
    33. 33. Direct Manipulation <ul><ul><li>Though often more expensive and risky, more direct manipulation of threatened species is often necessary in order to save threatened species from extinction. These include: </li></ul></ul><ul><ul><ul><li>Translocations – moving organisms from one habitat to another, </li></ul></ul></ul><ul><ul><ul><li>Artificial breeding – methods to increase reproductive output of small populations, </li></ul></ul></ul><ul><ul><ul><li>Maintenance of genetic diversity </li></ul></ul></ul>
    34. 34. Direct Manipulation Translocations <ul><ul><li>Translocation is the movement of living </li></ul></ul><ul><li>organisms from one area with free release </li></ul><ul><li>in another (IUCN, 1987). </li></ul><ul><ul><li>This can take three basic forms: </li></ul></ul><ul><ul><ul><li>introducing organisms outside its historically known native range.  </li></ul></ul></ul><ul><ul><ul><li>reintroducing organisms into environments from which it has disappeared or become extirpated.  </li></ul></ul></ul><ul><ul><ul><li>re-stocking existing populations that are very small with the intention of building up the number of individuals of that species in an original habitat.  </li></ul></ul></ul>
    35. 35. Direct Manipulation Artificial Breeding <ul><ul><li>Conservation biologists often alter the breeding systems of endangered species to increase their reproductive output. Some techniques that have been used are: </li></ul></ul><ul><ul><ul><li>Cross-fostering and double-clutching : increase reproductive output by removing the young (or eggs) to induce the parents to start breeding again more rapidly. Other closely related species are enlisted to serve as foster parents </li></ul></ul></ul><ul><ul><ul><li>Head-Starting : use of techniques to increase survivorship of young organisms that do not receive parental care, e.g. turtles </li></ul></ul></ul><ul><ul><ul><li>Hatcheries: raise fish that are at risk of extinction </li></ul></ul></ul>
    36. 36. Direct Manipulation Artificial Breeding <ul><ul><li>Conservation biologists often alter the breeding systems of endangered species to increase their reproductive output. Some techniques that have been used are: </li></ul></ul><ul><ul><ul><li>Artificial insemination : involves the impregnation of the female without direct sexual contact. Important when reluctant to mate or to reduce inbreeding </li></ul></ul></ul><ul><ul><ul><li>Embryonic transfer : embryo implantation into surrogate mothers, which sometimes can be of different – though closely related – species. </li></ul></ul></ul><ul><ul><ul><li>Studbooks & pedigrees : a studbook is a true record of pedigrees of animals and a listing of the various locations in which animals have been held </li></ul></ul></ul>
    37. 37. Maintaining Genetic Diversity <ul><ul><li>When a population passes through a bottleneck genetic drift results in a reduction in the overall heterozygosity, the number of different alleles, and the amount of additive genetic variation. This results in reduced population fitness, both by detrimental variants and reducing the genetic variation available for future adaptation (Miller & Hedrick, 2001). </li></ul></ul><ul><ul><li>Grizzly bear biologists are concerned that the population in and near Yellowstone National Park is so small and isolated that it may suffer from lack of genetic diversity. </li></ul></ul><ul><ul><li>Gene banking technology that would allow us to maintain genetic diversity independent of the wild populations will be quite a while coming, a rather dismal alternative is to having healthy, wild populations over the entire species geographic range. </li></ul></ul><ul><ul><li>Studbooks and pedigrees are used in captive breeding programmes to minimise inbreeding and maintain genetic diversity even in small populations. </li></ul></ul>
    38. 38. The Ex-Situ – In-Situ Interface <ul><ul><li>Ex-situ facilities can be critical components of a comprehensive conservation program </li></ul></ul><ul><ul><li>In many cases, habitat protection on its own is not sufficient, and direct intervention is required to mitigate or eliminate specific threats to species </li></ul></ul><ul><ul><li>Ex situ conservation (through captive breeding/artificial propagation) can offer insurance against extinctions by providing a source population for future re-introductions or reinforcement of wild populations. </li></ul></ul><ul><ul><li>Ex-situ conservation programs should supplement in-situ conservation by providing the long-term storage, analysis, testing and propagation of threatened species of plants and animals and their propagules </li></ul></ul><ul><ul><li>Augmenting wild populations with captive-bred individuals (Madsen et al. 1999) or removing organisms from the wild in to bolster captive populations and reduce inbreeding are two other possible uses of this ex-situ – in-situ interface </li></ul></ul>
    39. 39. The Ex-Situ – In-Situ Interface <ul><li>“ Ex-situ conservation should predominantly be used for the purpose of complementing in-situ conservation” (CBD, 1992) </li></ul><ul><ul><li>Parties signatory to the Conservation of Biological Diversity (CBD) are required to adopt measures, regulate and manage the recovery and rehabilitation of threatened species in ex-situ conditions followed by their reintroduction into their natural habitats under appropriate conditions </li></ul></ul><ul><ul><li>Modern zoos and aquaria have abandoned the old objective of exhibiting as many different species as possible. They try to focus on a few selected taxa whose wild populations can be helped most through the holistic ex-situ programs that incorporate maintaining healthy populations, education, research, and direct support of in-situ conservation projects </li></ul></ul><ul><ul><li>Within two or three decades, it may be necessary to devote most of the space in zoos to the captive breeding of endangered species. </li></ul></ul><ul><ul><li>Controversially there are only a few examples of ex-situ programmes returning an endangered species to the wild (Caughley, 1994) </li></ul></ul>
    40. 40. The Ex-Situ – In-Situ Interface <ul><li>“ Ex-situ conservation should predominantly be used for the purpose of complementing in-situ conservation” (CBD, 1992) </li></ul><ul><ul><li>Parties signatory to the Conservation of Biological Diversity (CBD) are required to adopt measures, regulate and manage the recovery and rehabilitation of threatened species in ex-situ conditions followed by their reintroduction into their natural habitats under appropriate conditions </li></ul></ul><ul><ul><li>Modern zoos and aquaria have abandoned the old objective of exhibiting as many different species as possible. They try to focus on a few selected taxa whose wild populations can be helped most through the holistic ex-situ programs that incorporate maintaining healthy populations, education, research, and direct support of in-situ conservation projects </li></ul></ul><ul><ul><li>Within two or three decades, it may be necessary to devote most of the space in zoos to the captive breeding of endangered species. </li></ul></ul><ul><ul><li>Controversially there are only a few examples of ex-situ programmes returning an endangered species to the wild (Caughley, 1994) </li></ul></ul>
    41. 41. Is there any point? <ul><ul><li>Given biblical precedence, it is not surprising that for millennia, a pair (male & female) has been deemed sufficient to initiate (Soulé, 1987). </li></ul></ul><ul><ul><li>Providing resources required to conserve threatened species, such as national parks, is costly and often conflicts with human demands, for example land-use. </li></ul></ul><ul><ul><li>On the other hand, captive breeding programs have been suggested as a partial solution </li></ul></ul><ul><ul><li>About 2000 endangered species require captive breeding, but space exists for only about 800 species </li></ul></ul><ul><ul><li>As a consequence of the described economic exigencies, conservationists, scientists, managers, even politics have converged on one question as a key to systematic conservation efforts and emblematic of the ability of science: </li></ul></ul>“ What is the minimum viable population of a threatened species?”
    42. 42. What is the minimum viable population (MVP) of a threatened species? <ul><ul><li>For a particular population or species, this question reduces to: </li></ul></ul><ul><ul><ul><li>Is the population large enough to avoid loss of reproductive fitness (due to inbreeding depression)? </li></ul></ul></ul><ul><ul><ul><li>Does the species have enough genetic diversity to evolve in response to environmental change? </li></ul></ul></ul><ul><ul><li>MVP for any given species in any habitat as the smallest isolated population having a 95% chance of remaining extant for 100 years despite the foreseeable effects of demographic, environmental, genetic stochasticity and natural catastrophes. </li></ul></ul><ul><ul><li>This does not signify that populations of lesser size have no future, only that their reproductive fitness and evolutionary potential are likely to be compromised, and they have an increased risk of extinction </li></ul></ul><ul><ul><li>The MVP has been estimated using simulation models, such as population viability analysis (PVA) </li></ul></ul>
    43. 43. Population Viability Analysis <ul><ul><li>PVA models begin essentially with the basic stock and population dynamics of the study species, such as birth and death rates, migration, sex ratio and age structure of the population. </li></ul></ul><ul><ul><li>To this may be added effects of spatial structure (e.g. the amount, quality, and availability of suitable habitat), environmental and demographic uncertainty, dispersal, catastrophes, inbreeding and genetic effects, and external deterministic processes such as habitat loss or hunting that impinge on a species’ chance of persistence. </li></ul></ul><ul><ul><li>PVA are based on models that relate a dependent variable (e.g. population size) to the independent variable (e.g. weather, harvest levels, mortality, etc.). The relationship between independent and dependent variables is mediated through the model’s parameters (e.g. survival rates and reproductive rates of individuals). </li></ul></ul><ul><ul><li>A single population projection is made over a specified time period. Second, many such predictions are made. Finally, the proportion of projections in which the population reached a certain threshold (e.g. extinction) is determined (Hunter, 1996). </li></ul></ul>
    44. 44. Minimum Viable Populations <ul><ul><li>The MVP size is intimately linked to the concept of effective population size, which can be defined as the ideal population which is able to maintain the same genetic diversity as the real population. </li></ul></ul><ul><ul><li>The 50/500 rule proposed by Soulé (1980) and Franklin (1980), which suggests that an effective population (N e ) of 50 is required for short-term persistence of population while an N e of 500 is required for long-term persistence, has been criticised and as a result lost importance as management goals. </li></ul></ul><ul><ul><li>This topic has been subject to a lot of debate e.g. the cheetah controversy </li></ul></ul><ul><ul><li>As Caughley (1994) puts it MVPs “have nothing to do with the size of a caribou population sufficient to cope with freezing rain in two successive years.” </li></ul></ul>
    45. 45. Minimum Viable Populations <ul><ul><li>Under IUCN Red List system, species are considered as critically endangered, endangered or vulnerable if population sizes are less than 50, 250 or 1000 mature individuals respectively. These correspond to an Ne of 5, 25 and 100, all within the range where inbreeding and loss of genetic diversity will undoubtedly occur over a relatively short period. </li></ul></ul><ul><ul><li>Loss of genetic diversity would not be of such a great concern if it were regenerated rapidly. </li></ul></ul><ul><ul><li>Thus the implication is that every effort must be made to prevent loss of current genetic diversity </li></ul></ul>
    46. 46. Minimum Viable Populations <ul><ul><li>Species with effective sizes below the minimum viable population suffer erosion of genetic diversity, and therefore reduced ability to adapt to novel environmental threats. </li></ul></ul><ul><ul><li>But are not necessarily doomed to immediate extinction. </li></ul></ul><ul><ul><li>Such species require increasing human intervention to ensure their survival. </li></ul></ul><ul><ul><li>Given the resources even a handful of organisms can be maintained to constitute a population or a species </li></ul></ul>“ There are no hopeless cases, only people without hope and expensive cases.” (Soule, 1987)
    47. 47. Case Studies <ul><ul><li>Conservation action frequently needs to be tailored to the specific circumstances affecting particular species. Several management techniques here described have been used in order to reduce the extinction risk of several threatened species. </li></ul></ul><ul><ul><li>Two illustrious case studies are the recovery of the black robin & the Mallorcan midwife toad </li></ul></ul>Black robin Mallorcan midwife toad
    48. 48. The Black Robin An amazing story of survival <ul><ul><li>The conservation of this robin is an internationally renowned success story; from bleak days in the 1980s, two thriving populations now exist. </li></ul></ul><ul><ul><li>The Black Robin ( Petroica traversi) is a small passerine endemic to the Chatham Islands (New Zealand). </li></ul></ul><ul><ul><li>Following human settlement of the islands, black robins declined rapidly as their forest habitat was lost and degraded, and due to predation by introduced rats and cats </li></ul></ul><ul><ul><li>For several decades prior to species; dramatic rescue in 1976, the world population of black robin was confined to privately owned Tapuaenuku (Little Mangere), a tiny, cliff-bound island in the Chathams </li></ul></ul>Chatham Islands Little Mangere Pitt Island Chatham Island SE Island
    49. 49. The Black Robin An amazing story of survival <ul><ul><li>In the 1976, when the population had declined to just seven birds, the remaining individuals were relocated to nearby Mangere Island, where 120,000 trees had been planted to provide suitable habitat. </li></ul></ul><ul><ul><li>Nevertheless decreased to five – the smallest population of any bird species for which precise figures were known at the time. </li></ul></ul><ul><ul><li>A period of intense manipulation began – nest protection, supplementary feeding, and a cross-fostering programmeprogramme (with congeneric Tomtit P. macrocephala ). </li></ul></ul><ul><ul><li>All the black robins alive are descended from that last breeding pair, named 'Old Blue,' and 'Old Yellow.' </li></ul></ul><ul><ul><li>Individuals were later introduced to South East Island (Rangatira), and by 1989 the population had topped 100 individuals, at which point management ceased. </li></ul></ul>
    50. 50. <ul><ul><li>The Mallorcan midwife toad ( Alytes muletensis ) was originally described in 1977 from fossil remains found on the island of Mallorca. </li></ul></ul><ul><ul><li>It was thought to be extinct for thousands of years until in 1979 living tadpoles and small toads of this species were discovered in a remote mountainous region of northern Mallorca </li></ul></ul><ul><ul><li>Fossil remains of this species suggested that it was widespread over much of Mallorca until about 2,000 years ago. This species has then greatly declined following the introduction of predatory viperine snakes ( Natrix maura ) and competing rats ( Rattus perezi ) </li></ul></ul>The Mallorcan Midwife toad
    51. 51. The Mallorcan Midwife toad <ul><ul><li>In view of the severe population fragmentation and continued decline (due to habitat loss) this species was classified as Critically Endangered in 1996 IUCN Red List of Threatened Animals </li></ul></ul><ul><ul><li>The first reintroduction of captive-bred toads occurred in 1989, when, at the request of the Mallorcan government, 76 tadpoles were returned to the island and released at two historic localities. Since then, releases of both young toads and larvae have occurred on a nearly annual basis, using animals from a number of the institutions breeding them. </li></ul></ul>
    52. 52. Conclusion <ul><ul><li>The IUCN Red List classification is recognised as the most objective and authoritative listing of species facing the threat of extinction. </li></ul></ul><ul><ul><li>It utilises five quantitative criteria for categorising the status of the species with respect to their chance of extinction. </li></ul></ul><ul><ul><li>The IUCN Red list categories and criteria have also increasingly been used for regional assessments of sub-globally species. </li></ul></ul><ul><ul><li>While the identification of the extinction risk faced by the species is important for priorities setting for its conservation, the biological, economic, social and cultural value of the species also need to be considered </li></ul></ul><ul><ul><li>A series of management interventions are required in order to control threats and increase the population size, both through in-situ and ex-situ management, to maintain the genetic diversity of the species. </li></ul></ul><ul><ul><li>Given the availability of resources even a ‘handful’ of organisms can be maintained to constitute a population or a species. However, with increasingly small and homozygous populations more intensive management is often required </li></ul></ul>
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    56. 56. Thanks for your attention This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/ or send a letter to Creative Commons, 444 Castro Street, Suite 900, Mountain View, California, 94041, USA.

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