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NATURE ECOLOGY & EVOLUTION 1, 0053 (2017) | DOI: 10.1038/s41559-016-0053 | www.nature.com/natecolevol 1
Articles
PUBLISHED: 27 fEBrUary 2017 | VOLUME: 1 | arTICLE NUMBEr: 0053
© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
Spending limited resources on de-extinction could
lead to net biodiversity loss
Joseph R. Bennett1*, Richard F. Maloney2, Tammy E. Steeves3, James Brazill-Boast4,
Hugh P. Possingham5,
6 and Philip J. Seddon7
There is contentious debate surrounding the merits of de-extinction as a biodiversity conservation tool. Here, we use extant
analogues to predict conservation actions for potential de-extinction candidate species from New Zealand and the Australian
state of New South Wales, and use a prioritization protocol to predict the impacts of reintroducing and maintaining popula-
tions of these species on conservation of extant threatened species. Even using the optimistic assumptions that resurrection of
species is externally sponsored, and that actions for resurrected species can share costs with extant analogue species, public
funding for conservation of resurrected species would lead to fewer extant species that could be conserved, suggesting net
biodiversity loss. If full costs of establishment and maintenance for resurrected species populations were publicly funded, there
could be substantial sacrifices in extant species conservation. If conservation of resurrected species populations could be fully
externally sponsored, there could be benefits to extant threatened species. However, such benefits would be outweighed by
opportunity costs, assuming such discretionary money could directly fund conservation of extant species. Potential sacrifices
in conservation of extant species should be a crucial consideration in deciding whether to invest in de-extinction or focus our
efforts on extant species.
Technological advances are reducing the barriers to resurrect-
ing extinct species or their close genetic proxies, allowing
de-extinction to be considered as a biodiversity conserva-
tion tool1,2. Arguments in favour of de-extinction include necessity,
driven by the rapid rate of species and habitat loss3,4, an ethical
duty to redress past mistakes5, as well as potential technological
and ecological knowledge that could stem from de-extinction pro-
grammes4. Counter-arguments include high risk of failure due to
difficulties of cloning for some species6, technical risks inherent in
re-introductions7–9, loss of culture in resurrected animal species8,
and lack of remaining habitat for some species10,11, as well as nega-
tive consequences for extant species, including reduced incentive
for traditional conservation12, and ecological impacts of introducing
long-absent or genetically modified species12.
The relative cost versus benefit for biodiversity is fundamental to
the debate surrounding de-extinction. Assuming species are resur-
rected to be released into former habitats, the cost of de-extinction
includes the process of producing initial founder populations,
translocating individuals, then monitoring and managing new wild
populations. If conservation funds are re-directed from extant to
resurrected species, there is risk of perverse outcomes whereby net
biodiversity might decrease as a result of de-extinction12,13. Although
private agencies might fund the resurrection of extinct species out
of technical or philanthropic interest, the subsequent ongoing
management of such species (many of which would face the same
threats that made them extinct) would fall on government agencies,
as commonly occurs with extant threatened species. Alternatively,
if private agencies are willing to provide new funding for post
de-extinction management, there could be additional benefits to
species sharing habitats or threats.
Here, we test the potential impact of establishing and sustaining
wild populations of resurrected extinct species (or proxies of such
species) on the conservation of extant species. Specifically, we use
long-term conservation programmes for extant analogue species
in New Zealand (NZ) and the Australian state of New South Wales
(NSW), to infer potential conservation actions for resurrected spe-
cies, and predict the impact of resurrected species programmes on
conservation of extant species. We use these datasets because they
contain detailed prescriptions and costs of actions designed to
achieve population recovery for most of the extant threatened spe-
cies requiring specific management actions in either jurisdiction.
We estimate the net number of extant species that can be conserved,
using the following scenarios: (1) establishment and maintenance of
resurrected species become the burden of government conservation
programmes, and (2) establishment and maintenance of resurrected
species populations are funded externally using non-public resources.
In Scenario 1, the use of government resources on resurrected species
results in less funding for extant species programmes, but provides
potential benefits for species that share actions with resurrected spe-
cies. In Scenario 2, there are also potential benefits to extant species
conservation programmes through shared conservation actions.
However, there are potential opportunity costs, if private agencies use
resources they could otherwise have used on conservation of extant
species. Our analysis assumes that species would be resurrected to be
re-introduced into their former habitats, rather than for other poten-
tial reasons, such as research or public display.
1Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada. 2Science and Policy Group, Department of
Conservation, 70 Moorhouse Avenue, Addington, Christchurch 8011, New Zealand. 3School of Biological Sciences, University of Canterbury, Private Bag
4800, Christchurch 8140, New Zealand. 4New South Wales Office of Environment and Heritage, 59 Goulburn Street, Sydney, New South Wales 2000,
Australia. 5University of Queensland, ARC Centre of Excellence for Environmental Decisions, School of Biological Sciences, St Lucia, Queensland 4072,
Australia. 6Conservation Science, The Nature Conservancy, 245 Riverside Drive, West End, Queensland 4101, Australia. 7University of Otago,
Department of Zoology, 340 Great King Street, Dunedin 9016, New Zealand. *e-mail: joseph.bennett@carleton.ca
2 NATURE ECOLOGY & EVOLUTION 1, 0053 (2017) | DOI: 10.1038/s41559-016-0053 | www.nature.com/natecolevol
© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
ARTICLES NATURE ECOLOGY & EVOLUTION
Because little is known about the costs of producing viable initial
populations of resurrected species, we do not consider this in our
analysis, and assume it is covered by a private agency. Instead, we
focus on the long-term cost of conservation for resurrected species,
assuming that such species would have small founder populations
that require conservation actions similar to those required for
extant threatened species.
Although there is considerable uncertainty regarding the neces-
sary conservation actions for many extinct species should they be
resurrected7, we assume that such species would share many actions
with closely related extant species that share habitats, threats and
ecological roles. Therefore, from among the endemic, fully extinct
species of our study areas, we chose focal extinct species whose
taxonomy, range, habitat, life history and threats were similar to
an extant threatened analogue species. Among 70 recently extinct
(AD 1000 to present) species in NZ, we found 11 for which we could
assign reasonable analogues (Supplementary Table 1). For NSW, we
considered 29 recently extinct species, and found 5 with reasonable
extant analogues. Our inferred conservation programmes for the
extinct species (assuming they were resurrected), were the same as for
their analogue extant species, with the addition of captive breeding
and translocation costs, based on average costs of captive breeding
and translocation from extant species of the same taxonomic group
(for example, bird, amphibian). Although cost and shared actions
were not criteria for choosing our focal species, our chosen group
represented a broad range in terms of estimated costs and the number
of extant species with shared actions (Supplementary Table 1).
Note that using analogues in this way probably underestimates
the cost, along with the risk of failure, and that we have assumed
that actions could be completely shared between resurrected and
extant analogue species. It is unlikely that an effective conserva-
tion programme for a resurrected species would completely share
actions with that of an extant species. Our analysis also includes
the largely untested assumption that technical barriers to creating
initial populations of these species can be overcome6,14. Thus, our
results should be regarded as optimistic in favour of the net benefits
of resurrected-species conservation programmes.
To assess the potential influence of resurrected species on extant
species conservation, we incorporated the proposed programmes
for resurrected species into threatened species project prioriti-
zation protocols developed for the New Zealand Department of
Conservation and the NSW Office of Environment and Heritage
(see ‘Methods’ for details). Costs of shared actions (for example,
predator control that benefits several species sharing a site) were
shared among prioritized species recovery projects. Thus, if private
funding covers the cost of actions for a resurrected species, the cost
of the same actions for any other species (including the resurrected
species’ analogue) would also be covered, potentially allowing more
species to be conserved within a given budget.
In Scenario 1, where resurrected species become the burden
of governments, we subtracted the budgets for resurrected spe-
cies conservation programmes from realistic baseline budgets for
NZ (NZD$30 million15,16) and NSW (AUD$4.65 million17), and
set the cost of any specific actions that were shared in location and
time with other species (for example, predator fence on a shared
habitat patch) to zero. We compared the number of extant species
that could be prioritized for funding in this scenario with the
number of extant species that would normally be prioritized
with the same baseline budget. We did this for each resurrected
species considered individually (cost of only one focal species sub-
tracted), as well as all resurrected species (11 for NZ and 5 for NSW)
considered together.
For Scenario 2, where resurrected species programmes are
entirely externally sponsored, we determined potential benefits
for conservation of extant species by setting the cost of any shared
actions between resurrected and extant species to zero, and re-ran the
prioritization algorithms with our baseline budgets. To determine
the opportunity cost associated with this scenario, we added the cost
of actions for resurrected species’ sponsorship programmes to the
baseline budget for extant species prioritization, then determined
the number of species that would be prioritized for conservation if
such funding could be used on extant instead of resurrected species.
For both NZ and NSW species, the number of extant species
that could be prioritized for conservation was generally lower in
Scenario 1, where resurrected species become the burden of the
government (Fig.1, red bars). This suggests a potential long-term
net loss of biodiversity if conservation efforts are shifted towards
resurrected species. For NZ, there were potential net gains associ-
ated with a single resurrected species, Coenocorypha chathamica.
This is because the conservation prescription for this species con-
tained many shared actions with 39 extant species that inhabit its
former habitat on Chatham Island. Shared costs for some of these
species allowed more to be prioritized than in the baseline scenario.
However, for NSW the estimated conservation costs for two extinct
species are greater than the most recent baseline budget estimate,
suggesting that the government budget would have to be drastically
increased if conservation of either species were publically funded.
Given that the NZ and NSW algorithms are designed to efficiently
conserve species using limited resources, and to account for shared
costs, it is possible that the impact of government payment for res-
urrected species programmes could be greater in other jurisdictions
where spending is less efficient.
In Scenario 2, where the conservation costs of resurrected species
are covered by an external agency, lowered costs of shared actions
would allow more extant species to be prioritized for conservation
(Fig. 1, yellow bars). However, the potential biodiversity benefits
are outweighed by the opportunity costs of not applying the same
funding to extant species (Fig.1, blue bars).
For both scenarios, including the costs of all resurrected species
together amplified the results (Supplementary Table 2). For exam-
ple, government-funded conservation for all 11 focal extinct species
in NZ would sacrifice conservation for nearly three times as many
0123
45
N/A
ab
–2 02
Number of species
prioritized
Number of species
prioritized
Figure 1 | Number of extant species prioritized for conservation for
different de-extinction scenarios. a,b, Mean differences in the number
of extant species prioritized versus the baseline number of prioritized
species when considering extant species only (vertical dashed line),
for New Zealand (a) and New South Wales (b). Red bars represent
Scenario 1, where conservation of resurrected species becomes the
responsibility of government. Yellow bars represent Scenario 2, where
conservation of resurrected species is externally sponsored. Blue bars
represent the number of extant species that could be prioritized for
conservation if funding for conservation costs of resurrected species could
instead be applied to extant species. Thus, they represent the opportunity
costs associated with Scenario 2. Error bars represent standard errors.
Note that the Scenario 1 costs for two species in NSW were higher than the
set government budget, so mean differences could not be measured (N/A).
NATURE ECOLOGY & EVOLUTION 1, 0053 (2017) | DOI: 10.1038/s41559-016-0053 | www.nature.com/natecolevol 3
© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
ARTICLES
NATURE ECOLOGY & EVOLUTION
(31) extant species. External funding for conservation of the five
focal extinct NSW species could instead be used to conserve over
eight times as many (42) extant species.
It is probable that including the costs of producing viable initial
populations of these species would greatly increase our estimates for
the sacrifices in extant species conservation. The costs for such pro-
grammes are difficult to project, but they are likely to be substantial.
A programme aimed at using stem cell technology and surrogates
to prevent the extinction of the northern white rhinoceros (which
would have fewer technical hurdles than resurrecting species from
only preserved materials) has been estimated to cost several million
dollars2. In addition, our analyses make the generous assumption
that we would have perfect analogues for the extinct species, such
that conservation programmes for resurrected and extant species
would share costs. Breeding and husbandry of resurrected species
before and after reintroduction could well be more expensive and
more prone to failure than for extant species, because we typically
know less about the behaviour and physiology of extinct species.
Reintroduction of locally extirpated species would likely have con-
siderably lower risk and costs, given better knowledge of the ecology
and physiology of such species.
Debates regarding the merits of de-extinction tend to centre
on either ethical or biological arguments. Ethical arguments often
focus on the potential of de-extinction to right past wrongs, versus
the ‘moral hazard’ arising from diminished motivation to conserve
extant species, if it is assumed that extinctions can be reversed some-
time in the (potentially distant) future12. Biological arguments often
focus on the relative benefit to biodiversity. For example, there may
be conservation gains through applying technical lessons learned in
the process of attempting de-extinctions4. There could also be gains
through restoration of ecosystem processes that were provided by
the extinct species18. For example, extinct ‘ecosystem engineers’,
such as woolly mammoths or passenger pigeons, could potentially
be resurrected in attempts to restore their lost functional roles19.
In addition, resurrected species could act as ‘flagships’ to promote
conservation5, and potentially increase resources for management
of extant threatened species.
However, there is considerable risk in assuming that resurrected
species would fill these intended roles. Resurrected ecosystem engi-
neers would be introduced into environments that have been much
altered by humans, and they could fail to thrive in these new circum-
stances7,19. Resurrecting populations large enough for such species to
fill their former roles could also prove very challenging19. Conversely,
there may be biodiversity losses if resurrected species become inva-
sive or spread disease12,20,21. Experience with extant iconic species
also suggests a high risk that iconic species resurrected as ‘flagships’
could draw resources away from programmes for extant species22, or
even create self-reinforcing biases whereby the public profile of res-
urrected species and resources spent on them would synergistically
increase, at the expense of non-iconic extant species23.
More fundamentally, de-extinction could lead either to bio-
diversity gains via resurrection of the extinct species themselves
and shared conservation actions with extant species, or to losses
through missed opportunities to allocate resources to extant species.
Conservation resources are scarce24, necessitating careful allocation
of funds25. Our analysis strongly suggests that resources expended
on long-term conservation of resurrected species could easily lead
to net biodiversity loss, compared with spending the same resources
on extant species. If the risk of failure and the costs associated with
establishing viable populations could also be calculated, estimates
of potential net losses or missed opportunities would probably be
considerably higher. Given this considerable potential for missed
opportunity, as well as the risks inherent in assuming a resurrected
species would fulfil its role as an ecosystem engineer or flagship
species, it is unlikely that de-extinction could be justified on grounds
of biodiversity conservation.
Methods
Focal extinct species were chosen based on taxonomic relatedness as well as having
ranges, habitats, threats and life-history strategies shared with extant analogue
species. We chose fully extinct species (not just locally extirpated) that went
extinct after AD 1000, assuming that feasibility of resurrection (for example,
availability of genetic material, knowledge of life history and physiology)
would be prohibitively low for species that went extinct before this time.
However, we did not assess the availability of genetic material in our focal species,
nor consider the feasibility or cost of producing viable initial populations.
Species conservation projects and prioritization algorithms. Species
conservation projects for all species in the NZ and NSW datasets (including the
analogue species) were determined using information gathered from threatened
species experts (> 100 experts for NZ, ~250 for NSW). The projects include the
specific actions (including specific location, timing and cost) considered necessary
to ensure ~95% probability of each species’ persistence over 50 years.
The prioritization algorithms rank species by the cost-effectiveness of
their conservation projects, using the following equation:
=
×
E
BS
C
iii
i
where Ei is the cost effectiveness of the conservation project for species i; Bi is
the benefit of the project to the species, defined as the difference between
estimated probabilities that a species will be secure in 50 years with and without
the project; Si is the estimated probability of success for the conservation project;
and Ci is the total cost of all actions for the project, across all sites. The NZ
algorithm uses an additional parameter that estimates a species’ evolutionary
distinctiveness (see ref. 15 for details). Costs of actions are shared among prioritized
species recovery projects. For example, the cost of predator control at a site
that benefits two prioritized species sharing the site is reduced by 50% for each
of the two species.
The algorithm begins with all species ranked, then eliminates the
lowest-ranked species sequentially until the set first-year budget is reached.
As species are removed from the ranks, cost sharing is updated for the remaining
species. Species that are no longer prioritized no longer share costs with those
that remain. Additional details regarding the algorithm are given in refs 15,26.
Data availability. The data and code for the NZ and NSW prioritization protocols
have been deposited in the Dryad Digital Repository at http://dx.doi.org/10.5061/
dryad.3qn55 and http://dx.doi.org/10.5061/dryad.p86t5, respectively.
Received 21 August 2016; accepted 13 December 2016;
published 27 February 2017
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Acknowledgements
J.R.B. was supported the Natural Science and Engineering Research Council of Canada
(NSERC) and the Australian Research Council (ARC) Centre of Excellence for
Environmental Decisions (CEED). H.P.P. was funded by an ARC Laureate Fellowship
and CEED.
Author contributions
J.R.B., R.F.M. and P.J.S. designed the study. J.R.B., R.F.M. and J.B.-B. analysed the data.
J.R.B. wrote the paper, with input from all other authors.
Additional information
Supplementary information is available for this paper.
Reprints and permissions information is available at www.nature.com/reprints.
Correspondence and requests for materials should be addressed to J.R.B.
How to cite this article: Bennett, J. R. et al. Spending limited resources on de-extinction
could lead to net biodiversity loss. Nat. Ecol. Evol. 1, 0053 (2017).
Competing interests
The authors declare no competing financial interests.
