Craig Stockwell, Andrew
Hendry & Michael Kinnison talk with
ScienceWatch.com and answer a few questions
about this month's Fast Moving Front in the field of
Plant & Animal Sciences. The authors have also
sent along images of their work.
Article: Contemporary evolution meets conservation
biology
Authors: Stockwell,
CA;Hendry, AP;Kinnison, MT
Journal: TREND ECOL EVOLUT, 18 (2): 94-101 FEB 2003
Addresses: N Dakota State Univ, Dept Biol Sci, Stevens
Hall, Fargo, ND 58105 USA.
N Dakota State Univ, Dept Biol Sci, Fargo, ND 58105
USA.
McGill Univ, Redpath Museum, Montreal, PQ H3A 2K6,
Canada.
McGill Univ, Dept Biol, Montreal, PQ H3A 2K6, Canada.
Univ Maine, Dept Biol Sci, Orono, ME 04469 USA.
Why do you think your paper is highly
cited?
Our paper synthesized two issues of contemporary interest to biologists and
society at large in applying an emerging paradigm shift in evolutionary
biology to the field of conservation biology. The traditional view of
evolution as a glacially slow process has been upended over the last
decade. Evolution has been shown to occur experimentally in the laboratory,
but until recently it was not well known whether evolution occurred very
often over contemporary time scales in nature.
Smatterings of case studies were well known, as documented in the Beak
of the Finch (Weiner, 1994), but the breadth of such "contemporary
evolution" was uncertain. Our analysis, as well as other reviews, suggested
that such contemporary evolution is relatively common (Stockwell and Weeks,
1999; Bone and Farres, 2001; Reznick and Ghalambor, 2001; Stockwell et
al., 2003; Kinnison, et al. 2007).
Andrew Hendry
Michael Kinnison
The goal of our paper was to look beyond simple demonstrations of
contemporary evolution and illustrate its importance in the current
biodiversity crisis. In particular, we noted that contemporary evolution
has been shown to be associated with the same human activities driving the
current extinction crisis; habitat degradation and destruction, exotic
species, climate change, and overharvest. Thus, evolution in contemporary
time may play a critical role in population persistence for both native and
introduced species and, as such, is of relevance to conservation
practitioners.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
Our work provides a synthesis of emerging knowledge and its extension into
the field of conservation biology. Contemporary evolution was
well-supported theoretically and enough empirical cases were emerging to
lead us to think it could be much more widespread than many people thought.
We synthesized this body of knowledge, but the real novelty of our paper is
that we explicitly examine the contexts for which evolution applies to
problems in the field of conservation biology.
Furthermore, we consider some of the factors that may constrain or
facilitate contemporary evolution. Understanding the factors that control
evolution is critical to allowing practitioners to apply evolutionary
principles to either facilitate or limit evolutionary responses.
Would you summarize the significance of your paper
in layman's terms?
Historically, it was thought that evolution was primarily a long-term
process that gave rise to modern biodiversity. For that reason conservation
practitioners tended to focus on ecological or genetic threats to diversity
while giving little attention to the idea that evolution might play a role
in their concerns. However, classic studies with Trinidadian guppies and
Darwin's finches showed that measurable evolution can occur in as little as
one generation (Reznick et al., 1990; Grant and Grant, 1995).
Such evolution is often associated with human activities that have
increased selection, but can also occur naturally when environments rapidly
change due to changes such as droughts (Hendry et al., 2008). In
the case of the finches, a severe drought resulted in a change in the
availability of seeds, so that finches with large beaks were able to forage
better than finches with smaller beaks. Many more studies have since been
published that provide comparable findings under different selective
circumstances, such as overharvesting, introductions of exotic species, or
habitat change.
Our contribution was to alert the conservation community that, because
evolution often occurs on the same time scale as many conservation
problems, it has real implications for preservation or restoration of
species in the wild. We explored how contemporary evolution is actually
expected under the very same circumstances that often lead to population
declines. Moreover, we suggested how various evolutionary processes could
aid or thwart their conservation objectives.
To appreciate this connection yourself, just imagine how some disturbance
in the environment due to human or natural processes might change what
traits are best for organisms that live there. The difference between what
traits exist in the population and what traits are "optimal" under those
new conditions determines the strength and direction of natural selection
(see Figure 1). If that mismatch is large enough it is likely that
selection may cause enough deaths or reduced reproduction to eventually
threaten the population.
However, if the population has sufficient genetic diversity (variation),
then some individuals will pass on the associated genes to the next
generation and thus change the average genetic traits of the population.
This is contemporary evolution. Much of our paper considers examples of
conservation-related issues that influence selection or genetic variation.
In a way, I guess you could say that we unveiled a new face of the
biodiversity crisis. Humans are not only causing species to go extinct at
unprecedented rates, we may also be rapidly changing the very traits of the
ones that survive (see Hendry et al., 2008 for a recent analysis
of this).
How did you become involved in this research and
were there any particular problems encountered along the way?
Stockwell: During my Ph.D. studies, I documented a case study of life
history evolution for non-native mosquitofish populations. As a student in
a newly established program in conservation biology at the University of
Nevada, I was curious as to the extent of such evolution and its potential
implications for conservation biology. A short review of recent literature
revealed that many case studies of contemporary evolution were associated
with introduced populations. Thus, contemporary evolution has implications
for the conservation of rare species which are often transplanted to new
and former habitats as a conservation measure (Stockwell and Weeks, 1999).
Our research begged the question as to the role evolution played in the
success and failure of conservation efforts. Independently, my
collaborators, Andrew Hendry and Mike Kinnison, had also documented cases
of contemporary evolution and had written two review papers that considered
the analyses of such contemporary evolution (Hendry and Kinnison 1999;
Kinnison and Hendry, 2001). Their analyses provided a framework for
comparing rates of evolution, and further demonstrated that such case
studies were rather common. It seemed that once scientists started looking,
cases of contemporary evolution were very common.
In point of fact, during the last decade, my research laboratory has
documented two additional cases of contemporary evolution (Stockwell and
Mulvey 1998; Collyer et al. 2005).
Our collaboration was a fusion of our collective interests in evolutionary
biology and conservation biology (Stockwell et al., 2003, 2006;
Kinnison et al., 2007). In reviewing the literature, it was
striking that contemporary evolution was associated with the same
anthropogenic forces driving the current extinction crisis. Our paper
considers the breadth of cases, but also provides an overview of how
evolution proceeds in wild populations. We also summarized the forces that
constrain and facilitate evolution such as gene flow. Our paper, as well as
other recent review papers, have collectively provided evidence that
contemporary evolution is relatively common and thus upends the traditional
view that populations are evolutionarily static (Reznick and Ghalambor
2001; Bone and Farres 2001; Ashley et al., 2003; Stockwell et
al., 2003; Kinnison et al., 2007). Our collaboration also
resulted in a manuscript to consider the relevance of contemporary
evolution to restoration ecology (Stockwell et al. 2006).
Where do you see your research leading in the
future?
This work has been well-cited in the scientific literature. Moreover, the
interest in evolutionary conservation biology is reflected by the recent
publication of books that take an evolutionary approach to conservation
biology (Ferrière et al. 2004; Carroll and Fox, 2008) as
well as the birth of new journals (Conservation Genetics, Evolutionary
Applications).
However, to this point, few studies have directly applied contemporary
evolution to conservation problems. The next step is for this work to be
applied by conservation practitioners to real world conservation problems
such as global warming and the spread of invasive species.
I am particularly interested in evaluating how evolutionary theory can be
directly applied to controlling the spread of invasive species as well as
mediating the impacts of invasive species on native ecosystems. My
coauthors are likewise exploring conservation-related applications, as well
as working on theoretical and experimental assessments of the role of
contemporary evolution in ecology in general.
Do you foresee any social or political
implications for your research?
Our research places evolutionary biology in a practical light that is often
under-appreciated by the general public. Certainly, the public has become
aware of applied evolutionary issues like antibiotic or pesticide
resistance, but often these examples are viewed as the odd workings of
microbes and insects. Our work emphasizes the dynamic nature of evolution
for essentially all of life as it marches lock-step with us on a changing
planet. As the public comes to appreciate this practical side of evolution
they will hopefully appreciate the central role evolutionary theory should
play in everyone's science education.
The practical relevance to evolutionary theory of medicine has been well
documented and now plays a role in the administration of antibiotics.
Likewise, the management of natural systems should be considered in an
evolutionary context. Traditionally, conservation biologists and ecologists
alike have considered evolutionary processes as long-term concerns.
However, an emerging paradigm shift is underway that allows evolutionary
ecologists to consider the contemporary interaction of evolutionary and
ecological processes.
Recent analyses have shown that evolution can play an important role in
population dynamics and ecological processes (Hairston et al.
2005; Kinnison and Hairston, 2007). This area is ripe for more extensive
and collaborative studies amongst evolutionary biologists, ecologists, and
conservation biologists.
In the arena of global change biology, this emerging paradigm has important
implications. The traditional view has been that populations unable to
migrate due to habitat fragmentation would be doomed to in-situ
extirpation. However, population persistence probability may be increased
if such populations have sufficient phenotypic plasticity (Charmentier
et al., 2008) or genetic variation to evolve in situ. To
date, many case studies have shown that populations can respond
appropriately to climate change in situ, but few of these studies
have demonstrated if the observed response(s) were due to evolution,
plasticity, or both phenomena (Gienapp et al., 2008, see also
Charmentier et al., 2008).
The importance of this issue begs for more carefully designed studies to
evaluate the plastic and evolutionary potential responses of populations to
global climate change. Ultimately understanding the potential for
populations to respond will be important for establishing an applied
evolutionary approach to global climate change. For instance, the potential
for species to respond to global climate change will vary widely within a
community, thus which species are likely to persist will require detailed
ecological and evolutionary data.
Craig A. Stockwell
Associate Professor
Department of Biological Sciences
North Dakota State University
Fargo, ND, USA
Michael T. Kinnison
Associate Professor of Biological Sciences
School of Biology and Ecology
The University of Maine
Orono, ME, USA
Andrew P. Hendry
Associate Professor
Redpath Museum and Department of Biology
McGill University
Montreal, Canada