Projected rates of climate change could put several species at risk of extinction. In order to persist, species need to either adapt to new climates or move new locations that will match their preferred climate in the future. Though climate change might seem gradual to us, the climate is projected to change so rapidly that several several species cannot reach those new locations on their own. Especially at risk of extinction are species like trees, that do not spread their seeds very far, or corals, that are sensitive to environmental conditions.
In response, several conservation biologists and environmental managers have been considering picking up these slow-moving species and moving them in a conservation strategy known as managed relocation or assisted migration. However, if someone moves a species, it could become invasive in its new location. Moreover, some people might not be happy with a new species in their backyard. With so much uncertainty in climate and ecological interactions, it is important that we understand the risks and benefits of this proposed conservation strategy.
We might also consider alternative management strategies to protect climate threatened species without explicit managed relocation. With assisted gene flow, individuals could be relocated within a species' historical range to exchange genes that promote climate resilience. Also, by increasing local climate heterogeneity, we increase the diversity in habitat types within a small area. Therefore, species might not need to move as far to reach optimal future climates.
If you are also interested in a broad overview of managed relocation and alternatives, please consider reading these following papers from other researchers.
In response, several conservation biologists and environmental managers have been considering picking up these slow-moving species and moving them in a conservation strategy known as managed relocation or assisted migration. However, if someone moves a species, it could become invasive in its new location. Moreover, some people might not be happy with a new species in their backyard. With so much uncertainty in climate and ecological interactions, it is important that we understand the risks and benefits of this proposed conservation strategy.
We might also consider alternative management strategies to protect climate threatened species without explicit managed relocation. With assisted gene flow, individuals could be relocated within a species' historical range to exchange genes that promote climate resilience. Also, by increasing local climate heterogeneity, we increase the diversity in habitat types within a small area. Therefore, species might not need to move as far to reach optimal future climates.
If you are also interested in a broad overview of managed relocation and alternatives, please consider reading these following papers from other researchers.
- A framework for debate of assisted migration in an era of climate change (McLachlan et al. 2007)
- Assisted colonization is not a viable conservation strategy (Ricciardi et al. 2009)
- Taking stock of the assisted migration debate (Hewitt et al. 2011)
- Managed relocation: Integrating the scientific, regulatory, and ethical challenges (Schwartz et al. 2012)
- Assisted gene flow to facilitate local adaptation to climate change (Aitken and Whitlock 2013)
Identifying robust strategies for assisted migration given risks and uncertainties in a stochastic metacommunity
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We created a multi-species mathematical model that simulates how species move with changing climates. Because some of the simulated species cannot keep up with climate change, we relocate a species to its optimal climate if it falls below a critical, low-population threshold. We found that assisted migration performs best when we relocated a fraction (around 50%) of the total species’ population, as temporarily retaining the population in the original location could allow managers to repeat relocation in case the species fails to establish the first time. Also, competition from other species could limit the practicality of assisted migration. We found that assisted migration was less successful when relocating a species into areas already occupied by its competitors, even if that area would have been an optimal climate in a single-species context. Additionally, assisted migration did not appear to affect non-target species, implying that the risk of invasion is unlikely to arise from competition as compared to other species interactions (e.g., predation, disease spread).
This paper is currently under review, but a preprint is currently available on bioRxiv or you can email me for a copy. If you are also interested in learning more about decision making for managed relocation models, you should also consider these papers from other researchers
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A structured decision making approach to managed relocation
As experts are trying to make sense of the risks of managed relocation, the practice is already underway for many species. In response, we outline how employing a structured decision making framework could allow the conservation community to carefully move forward while addressing key knowledge gaps that impede progress in understanding the risks and benefits. This work is largely based on topics that were discussed during at 2017 international symposium at the University of California, Davis entitled “Managed Relocation Under a Changing Climate: An Interdisciplinary Perspective Symposium”. In particular, we describe how specifying clear and quantifiable conditions for success and failure could allow decision makers to reduce the unprecedented scale of managed relocation and its associated risks. Next, we describe how placing assisted migration alongside alternative conservation strategies, instead of treating it as a last-resort strategy, can open up opportunities to test managed relocation in lower risk scenarios. We discuss how we can leverage expert elicitation and previous translocation experiments across environmental gradients to estimate risks and benefits of relocations across these unprecedented scales. Finally, after outlining a variety of risks on genetic, population, community, and social scales, we consider how adaptive management with explicit exit strategies could limit negative outcomes while learning how to avoid risks in the future.
This paper is currently under review, but if you're interested in reading a preprint, please email me for a copy. If you are also interested in learning more about decision making for managed relocation, you should also consider these papers from other researchers |