Friday 5 June 2015

Conservation, Ecosystems and Evolution 101

Conservation challenges of predator recovery - Conservation Letters

If anyone seriously doubts that evolution happens and can be seen to be happening, simply observing what happens when conservation measures inevitably change the ecosystem should convince them they are wrong.

The only way to retain a belief that evolution can't happen is to use the tried and tested creationist technique of simply ignoring the evidence and maintaining a belief at the expense of intellectual integrity.

For example, we have this account published in Conservation Letters yesterday in which scientists from the NOAA Fisheries' Northwest Fisheries Science Center and the University of Washington identified three different effects of recovering predator numbers due to conservation efforts in two different US ecosystems - the West Coast and Greater Yellowstone ecosystems. These were:

  • Increased competition with humans for the same prey - sea lions eating fish; wolves preying on livestock and elk.
  • Predators eating protected or at-risk prey species - sea lions eating salmon; grizzlies eating cutthroat trout.
  • Protected predators competing for prey - sea lions eating the same fish as killer whales; wolves and grizzly bears competing for the same prey.

Predators are critical components of ecosystems. Globally, conservation efforts have targeted depleted populations of top predators for legal protection, and in many cases, this protection has helped their recoveries. Where the recovery of individual species is the goal, these efforts can be seen as largely successful. From an ecosystem perspective, however, predator recovery can introduce significant new conservation and legal challenges. We highlight three types of conflicts created by a single-species focus: (1) recovering predator populations that increase competition with humans for the same prey, (2) new tradeoffs that emerge when protected predators consume protected prey, and (3) multiple predator populations that compete for the same limited prey. We use two food webs with parallel conservation challenges, the Northeast Pacific Ocean and the Greater Yellowstone ecosystem, to demonstrate legal/policy conflicts and the policy levers that exist to ameliorate conflicts. In some cases, scientific uncertainty about the ecological interaction hinders progress towards resolving conflicts. In others, available policy options are insufficient. In all cases, management decisions must be made in the face of an unknown future. We suggest a framework that incorporates multispecies science, policy tools, and tradeoff analyses into management.

Copyright © 1999-2015 John Wiley & Sons, Inc.

The authors produced the following matrix to illustrate these emerging or potential conflicts:
Class of Conservation ConflictNortheast Pacific marine mammal-ChinookGreater Yellowstone Ecosystem
Ecological conflictScientific UncertaintyPolicy conflictEcological conflictScientific UncertaintyPolicy conflict
1. Protected Predator vs human usePinnipeds vs Chinook salmonDo predators substantially reduce salmon fishery yields?MMPA vs human useWolf-ElkWhat is the relative importance of wolves, other predators, humans, and climate in controlling elk population productivity?ESA-vs human use
2. Protected Predator vs Protected PreyOrcas vs Chinook salmonWhat fraction of endangered salmon runs are eaten by orcas?ESA vs ESAGrizzly v CutthroatHow much do grizzly bears contribute to mortality on cuthroat trout?ESA-ESA
3. Protected Predator vs Protected PredatorOrcas vs PinnipedsWould deterring or culling pinnipeds help orcas?ESA vs MMPAWolf vs GrizzlyWhat is the strength of competition between these two predators?ESA-ESA
MMPA = Marine Mammal Protection Act; ESA = Endangered Species Act.
Copyright © 1999-2015 John Wiley & Sons, Inc.

The whole tenor of this paper is that changes in one component of an ecosystem, especially the number of predators, will ripple throughout the ecosystem, changing the relative numbers of other species, particularly prey species.

The particular concern here is that one measure such as the Marine Mammal Protection Act can conflict with another such as the Endangered Species Act, but the greater point is that changes don't happen in isolation in an ecosystem; the entire ecosystem is affected.

So, if you don't believe in evolution, what do you think is going on here?

Or maybe you don't believe that more predators means that more prey species will be eaten and that falling populations of prey species means that there will be fewer for the predators, including humans, to eat. If so, there is probably no point in reading on, even if you managed to get this far, because you are clearly determined to hold beliefs which run directly counter to the facts and which defy logic.

Okay, so you DO believe that change in one population will lead to changes in other populations in an ecosystem.

Now, what do you think would be the result of some prey being better at escaping from or hiding from predators, or the result of some predators being better than others at finding the declining numbers of prey? Is there any reason you can think of why a member of a prey species which is good at avoiding getting eaten would not produce more offspring on average? And is there any reason you can think of why those offspring would not inherit their parents' avoidance abilities?

Is there any reason why a predator which is better at catching prey would not produce more offspring on average or any reason why those offspring should not inherit their parents' hunting ability?

If you can't think of any reasons why in these situations the prey species as a whole should not gradually become better at avoiding getting eaten and the predators should not become better at finding prey - in other words, an evolutionary arms race would ensue - then you can't logically argue that scientific evolution doesn't happen. I've use the term 'scientific evolution' (change in allele frequency over time) to distinguish it from creationist 'evolution' which is a deliberate parody of the science, intelligently designed to be easy to attack to convince scientifically illiterate people that evolution doesn't happen.

So, since scientific evolution is not only possible but can be observed and forms the backdrop to the conservation issues highlighted by this paper, where does this leave the creationist industry's constant insistence that there is some physical law acting to prevent it? If you're a creationist and you've managed to read this far, you can probably join the dots and answer that for yourself.

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