Author Archives: Reid Brennan

En garde! Assortative mating in hybrid swordtails

Posted on 9 Nov, 2017 by Reid Brennan

Understanding reproductive isolation is a pretty darn important part of understanding evolution. For new species to form, gene flow needs to be limited in some way. Under allopatry, limiting gene flow is straight forward; individuals never encounter each other so … Continue reading →

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Habitat-matching dispersal facilitates local adaptation

Posted on 15 Sep, 2017 by Reid Brennan

Migration disrupts local adaptation. At least, this is the first reaction I have when I consider these two processes. In fact, my initial thought is almost always: how strong does selection have to be to overcome gene flow? Gene flow … Continue reading →

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Experimental harvesting reduces gene expression variation

Posted on 10 Aug, 2017 by Reid Brennan

Human activities represent unique selective pressures for natural populations. This is especially true for fish species where we routinely harvest individuals from the wild, i.e., through fishing. It has been recognized for some time that overfishing can result in population … Continue reading →

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Hybridization and adaptive radiations

Posted on 20 Mar, 2017 by Reid Brennan

As an iconic system in evolutionary biology, I’ve always been interested in African cichlids and the origins of their diversity1. These cichlids represent an adaptive radiation; they’ve evolved rapidly from a single origin to exploit and speciate into open niches … Continue reading →

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Conifer convergence

Posted on 17 Oct, 2016 by Reid Brennan

Convergent local adaptation is typically studied within a species or between closely related species. In these cases, it is perhaps not unexpected to observe parallel evolution due to common genetic variation, constraints, etc. Convergence between species is somewhat less studied, … Continue reading →

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The trouble with PCR duplicates

Posted on 25 Aug, 2016 by Reid Brennan

The sequencing center just sent your lane of Illumina data. You’re excited. Life is great. You begin to process the data. You align the data. You check for PCR duplicates. 50 percent. Half of your data is garbage. Everything is … Continue reading →

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New insight into the genetic basis of industrial melanism

Posted on 9 Jun, 2016 by Reid Brennan

The evolution of coloration in peppered moths during the industrial revolution is one of the most well known examples of natural selection in action. Part of the appeal of the system is the apparent simplicity. The once-abundant light colored morph … Continue reading →

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Steelhead in a random forest: identifying the genetic basis of migration

Posted on 25 May, 2016 by Reid Brennan

Genome-wide association studies (GWAS) have been quite successful in identifying variants associated with various phenotypes (I suppose there is some debate surrounding this statement. For an interesting, if dated, discussion look here). While most of this work was originally conducted … Continue reading →

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The simpler cichlid: a recent adaptive radiation

Posted on 21 Apr, 2016 by Reid Brennan

If I was asked to name a few of the most compelling systems in evolutionary biology, I’d certainly start with Darwin’s Finches. Next might come peppered moths, African cichlids, stickleback, Caribbean Anolis lizards, or Lenski’s E. coli. What’s interesting about … Continue reading →

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Genomic Islands of Speciation… are real?

Posted on 22 Mar, 2016 by Reid Brennan

I really want genomic islands of speciation to be real. Those great studies that seemed so convincing over the last ~10 years have been squashed due to, among other things, the trickiness of low genetic diversity (stay with me, I’ll … Continue reading →

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