Evolutionary Ecology
The intersection of these two fields was the broad focus of my Master's thesis. This page is a general introduction to how I think about evolutionary ecology.
Some background ~
In evolutionary biology, fitness refers to an individual's ability to survive and reproduce. Darwin commonly used ecological examples of when describing selective pressures acting on fitness. In such cases, traits of the focal individual determine how it will interact with other individuals. If those traits are "good enough", allowing the individual to survive long enough to reproduce, they will be passed on to the next generation.
This foundational mechanism of evolution, so clumsily summarized above, has obvious implications for the field of ecology. The way that organisms interact with one another is certainly a central driver of natural selection. I would go so far as to say that most people, when asked to describe an example of natural selection, would describe one of the many flashy evolutionary arms races1 they learned about in high school or college biology class. However, the ecology-influences-evolution mechanism, or eco -> evo, is only half of the story.
Eco-evo feedback ~
Despite the axiomatic connection between evolution and ecology, these fields diverged early in the twentieth century and walked separate paths until recently. Part of this disconnect can probably be attributed to a disparity in perceived temporal resolution. Ecology is generally studied on a timescale most convenient and relevant to us humans, while evolution is usually framed as the slow accrual of small genetic changes over epic lengths of time.2 Therefore, while it has always been accepted that ecology can cause evolutionary change, the inverse effect of evolution on ecology (evo -> eco) is a much less comfortable idea for some. In fact, if adaptive evolution occurs quickly enough it can have meaningful effects on species interactions on a timescale relevant to ecological processes, such as extirpation and extinction, changes in range, biological invasion success, etc. (The potential for rapid adaptive evolution depends on several factors, one of the most important being sufficient heritable variation in relevant traits3 -- the focus of Ch. 1 of my MS thesis.)
Climate implications ~
It is at this point in our discussion that climate change makes its entrance. One of the more exciting possibilities brought forth by the concept of rapid adaptive evolution is evolutionary rescue. As the climate on Earth changes, some lucky populations might be saved right at the brink of extinction. Through the familiar process of natural selection, here acting at breakneck speed, populations threatened by climate change are "rescuing" themselves over just a few generations. This becomes more possible at smaller population sizes, as rare beneficial alleles can spread much more quickly. Before you get too excited and go join a climate change denial forum, there are two important caveats to this process:
(1) Considering how much research effort has gone into searching for examples of evolutionary rescue occurring in nature, it is fair to say this route to climate salvation is considerably rare. Those rare beneficial alleles have to be present in the population in the first place, which is a huge hurdle for most species in general, but is especially rare for species endemic to historically consistent climates (e.g., marine organisms).
(2) Species do not exist along in their environment. Rapid changes in the traits of one species, even if in response to a completely different selective pressure, can have indirect effects on interactions with other species in the community (e.g., competition, predation, mutualism, etc.).
This second point describes effects that have been given a special name: evolution-mediated indirect effects on ecology.4 Such effects likely do exist, but empirical evidence is difficult to find. Disentangling the effects of plasticity (i.e., acclimatization) and confounding biotic and abiotic direct effects from the results of evolutionary change is challenging. Designing an experiment capable of isolating evolution-mediated indirect effects requires some careful thought, and is exactly what I did for Ch. 2 of my MS thesis.