A map for defending your PhD

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Evolution on an ecological scale

Andrew Gonzalez, Ophélie Ronce, Regis Ferriere, and Michael E. Hochberg. 2013. Evolutionary rescue: an emerging focus at the intersection between ecology and evolution. Philos Trans R Soc Lond B Biol Sci. 368 (1610).doi: 10.1098/rstb.2012.0404 (Intro to special issue).

David A. Vasseur, Priyanga Amarasekare, Volker H. W. Rudolf, Jonathan M. Levine. 2011. Eco-Evolutionary Dynamics Enable Coexistence via Neighbor-Dependent Selection. The American Naturalist, Vol. 178, No. 5, pp.E96-E109.

Ecology and evolution are often treated as connected but ultimately discrete areas of study. Ecological processes are usually the main source of explanation for ecological patterns and  ecologists may ignore evolutionary processes under the assumption that these are most important over longer time scales than are of interest (e.g. speciation). However, there is also an increasing recognition that rapid evolutionary dynamics can contribute to ecological observations. In a time where rapid changes to climate and habitat are the greatest threats to most species, the suggestion that rapid evolution might play a role in extinction prevention and diversity maintenance is an important one.

Increasingly researchers are exploring this concept. The concept of evolutionary rescue (ER), has been particularly championed by Andy Gonzalez and Graham Bell of McGill University. ER results when evolution occurs fast enough to arrest population declines and allow populations to avoid extinction in the face of changing conditions. Changing conditions resulting in maladapted populations should result in population declines followed by extinction. However, if selection for resistant types (which are present in the population, or result from mutations) occurs, population declines can be countered. The result is a characteristic u-shape curve, showing the initial geometric decline, followed by a geometric increase – escape from extinction is then a balance between rates of evolution and success of resistant types compared to rates of population decline.

From Bell & Gonzalez 2009.

The question of whether evolution may have relevance to population declines is not precisely new, but it is especially relevant given we are in a period of habitat changes and extinction. A special issue of Proc B is focused only ER, on the question of its importance, prevalence, and predictability. Many of the articles extend theory, exploring assumptions about the type of environmental change, type and extent of the threat, presence of dispersal, spatial gradients, etc. A few articles attempt the more difficult task of testing for ER in natural systems and assessing its likely prevalence and value to conservation activities. It is an interesting journal issue and a great example of the importance of context in determining when an idea takes off. The theoretical background for evolutionary rescue has existed for many years, but it took the context of climate change (and perhaps the collaboration of an ecologist and evolutionary biologist?) for it to gain ground as an area of ecological research.

Another interesting paper, this one linking evolutionary dynamics with community coexistence, is from Vasseur et al. (2011). In this case, the authors suggest an evolutionary mechanism that could augment coexistence when ecological conditions allow for niche partitioning and that could allow coexistence when ecological conditions lead to competitive exclusion. If species exhibit tradeoffs between traits that are optimal for intraspecific interactions and traits that are optimal for interspecific interactions, evo-ecological dynamics can produce coexistence. Such tradeoff means that a species will be a superior interspecific competitor when rare and a poor interspecific competitor when common. Such a tradeoff creates neatly alternately selective pressures depending on whether a species is common (fitness declines) or rare (fitness increases). This is presented as a theoretical model, but it seems like in a tractable system one could easily test for changes in ecological and evolutionary pressures as predicted by the model.

No one would argue with the conclusion that a closer relationship between ecology and evolutionary biology would be beneficial for both. But in practice this seems to be the exception rather than the rule. "Evolutionary ecology" as it exists is fairly restricted, and if complaints about seminar topics is to provide a hint, most ecologists feel disconnected from evolutionary topics and vice versa. If evolutionary dynamics are relevant on an ecological scale, it seems that we should at least attempt to understand their prevalence and importance in natural systems.

Ecology in everyday life: Monday links

To start, it’s reassuring to know that honeybees like caffeine too. So as you sip your coffee, know that you aren’t the only species who benefits from a little something to start the day.

Citizen science success. iNaturalist.org provides a platform for interested citizens to collect and submit observational data for a huge variety of taxa. This creates an expanding database of species IDs and geographical locations across the US. At present, they have 200,000 observations, which is pretty amazing.

Beautiful wildlife gifs, a reminder that nature is an astonishing place.

Predator/Prey. For some ecologists, work and creative undertakings overlap. So with this in mind, I wanted to point out a band that has taken this marriage of art and ecology to the extreme. Predator/Prey is a Canadian band headed by Dak de Kerhove and Adam Phipps that has released an album built around the concept of species interactions. Dak de Kerkhove is a PhD student studying predator-prey interactions between fish with Peter Abrams and Brian Shuter, so in this case art imitates life.

Most of the songs take inspiration from a combination of emotional subtext and ecological theory. For example, “A Run of Rabbits” focuses on prey dynamics and red queen, with the prey ever running to stay in one place. “Plump of Grouse” is inspired by death and predator prey cycles and written from the perspective of a predator. Because de Kerkhove's work has taken him to the far North, the band can't tour, and instead decided to release a web game that allows you to experience predator-prey interactions from the perspective of a fox. Pretty cool.

**The ecological connections are sometimes subtle, so here is the cheat sheet I was given**
Unkindness of Ravens (INTELLIGENCE / MUTUALISM)
Bed of Mussels (ENDURANCE / PASSIVE FORAGING)
Sounder of Boar (REVENGE / LOSS OF TRAITS UNDER DOMESTICATION)
Knot of Snakes (DESIRE / MATE COMPETITION)
Skulk of Foxes (LOSS / MONOGAMY)
Rout of Wolves (POWER / SOCIAL HIERARCHY)
Priory of Panthers (COOPERATION / GAME THEORY)
Plump of Grouse (DEATH / PREDATOR PREY CYCLES)
Mischief of Mice (OVERWHELMED / COMPETITION)
Shoal of Fish (DEDUCTION / CREPUSCULAR FORAGING)
Run of Rabbits (FEAR / RED QUEEN)
Gang of Elk (ACCEPTANCE / SELFISH HERD)
Piteousness of Doves (LOSS / GAME THEORY) 
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