Ask Us Anything: PhDs from outside N. America and Europe, and the current status of classic ideas in life history theory

A while back we invited you to ask us anything. Here are our answers to our next two questions, from Johan Argovis and Carlos Trigueros, respectively:

  1. When seeking a faculty position in N. America, is it a disadvantage to hold a Ph.D. from outside N. America or Europe?
  2. What’s the current status of Grime’s CSR theory and r-K selection in ecology? In particular, why is r-K selection regarded as obselete or incorrect?

Jeremy’s answers:

  1. Good question to which I’m unsure of the answer. I think it probably depends on the rest of your cv. If the rest of your cv (and other application materials) are those of someone who would be competitive for the position for which you’re applying, I don’t think where you got your PhD will matter too much. For instance, to be competitive for a faculty position in ecology at a large research university you’ll probably need some first-authored publications in leading international journals. And it would definitely help to have done a postdoc in N. America, Europe, Australia, or New Zealand, and to have reference letters from people who are familiar with the N. American system and who can speak to your readiness to hold a faculty position in N. America even though your background is from elsewhere.
  2. I have an old post on one problem with r-K selection. But I’m far from an expert on life history theory. I think if you want an overview of current thinking, your best bet is to start with Steve Stearns’ book and work forward from there. Certainly, density-dependence will affect the optimal life history, so there’s a germ of truth in the idea of r-K selection. But r-K selection isn’t the best way to express that germ of truth.

Brian’s answers:

  1. I think the CV dominates everything else. Papers published in good journals are what gets you faculty jobs in research universities. That and fit in terms of research area. Everything else like reference letters, prestige of the institution for your PhD come in just as tie breakers within very similar looking CVs. So on that small level applying for jobs in N. America you are helped by having a N. America, Europe or Australia/New-Zealand PhD. But a PhD from a country with a slightly less developed research reputation or even a much less developed research reputation can very definitely be overcome by the CV. As Jeremy noted, having a postdoc in N. America/Europe is just as good as having a PhD from there.
  2. I’m more of a fan of r-K selection than Jeremy. Jeremy’s link is correct that some of the focus on the r & K parameters in the logistic equation are unfortunate. And r-K very quickly turned into a non-concept with long tables published of r vs K traits (Pianka) that didn’t come from any theory. That more than anything else is I think what turned r-K into a smart ecologists don’t talk about it topic in ecology. But life history theory very much changes under density dependent vs non-density dependent conditions. Roughgarden has some nice papers showing that as a population grows, the best measure of fitness changes from r (growth-rate in low-density conditions) to K or equivalent (ability to maintain a large population under high-density conditions). There are some interesting parallels of that idea with the R* theory of MacArthur and Tilman. But coming from a completely different direction, simple PCA analysis of life history traits (that correct for body size) repeatedly pull out what is called the fast-slow continuum. Some species grow fast, reproduce early and die young. And some grow slowly, reproduce later, and live a long time. This same notion applied to a single organ becomes the leaf economic spectrum beloved by plant trait people. So quite aside from theory there is some empirical validity that a major organizing principle is the fast-slow life styles. What is missing is the linkage between fast-slow life styles and density dependent vs density independent life histories. There may be such a linkage. Or the two notions may be entirely independent (despite the teaching of most ecology textbooks). Most life history theory links fast-slow life styles more to mortality (e.g. predation risk, disturbance). As for Grime, I would say it remains a bit controversial although certainly well-known. I have a very hard time mathematically understanding 3-way trade-offs. I find two axes of trade-off much more tractable. And I personally find both Southwood 1998 and especially Winemiller (two papers in 1992) much more convincing extensions to a 3-way trade-off.

4 thoughts on “Ask Us Anything: PhDs from outside N. America and Europe, and the current status of classic ideas in life history theory

  1. Hi Brian and jeremy; your remarks on r/k are quite sensible, brief, and historically correct.
    Age structured LH theory, evolving things like reproductive effort, age/size at maturity, optimal offspring size, ageing, etc became the norm; indeed they were present from the 60s[ GC Williams 1957,1966], early 70s[ Smith& Fretwell 74], and with RA fisher in his 1930 book!
    Interestingly Pianka both extended r/k to life histories, and did optimal reproductive effort theory.
    One can use r as a fitness measure, or introduce density dependence into the LH somewhere, and reduce r to zero in the final answer, [more or less] equivalent to using Ro as fitness, while holding Ro near [=] 1.

    From Brian:
    .” What is missing is the linkage between fast-slow life styles and density dependent vs density independent life histories. There may be such a linkage. Or the two notions may be entirely independent (despite the teaching of most ecology textbooks). Most life history theory links fast-slow life styles more to mortality (e.g. predation risk, disturbance).”

    There is no necessary connection; Density dependent LH theory , with Ro as the fitness measure [ Ro ~1 through Density dependence present somewhere] accounts very nicely/easily for the features of the slow/fast continumn ‘see:: http://digitalrepository.unm.edu/biol_fsp/25/ for mammals. As you note, growth rates [ production rates] for an individual in the face of mortality risk determining the size at maturity is a key component.

    The Reznick paper suggested by Erik above is very good.

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