This book is dry in the extreme. To honor that, this review will
itself be extremely dry. Just kidding...or am I? You decide. It
took me a year to wade though Relentless Evolution and I
certainly wouldn't recommend it as a light beach read. The
citations along extend for over a hundred pages!
Adaptive Evolution
Thompson opens his tome talking about adaptation. This seems
to be as good a place to start as any. Adaptation is certain
traits which lead to successful reproduction in a given
environment being favored in that environment. This provides a
nice entry for him to talk about how whereas once we saw
evolution as a long historical process today we can see viruses,
insects, bacteria and other organisms with short reproduction
times evolve. Indeed, it seems like there's a new strain of the
flu to fight off every year.
Natural Selection
This'd be your classic Darwinian process: more individuals with
variant A of a trait survive to reproduce than those individuals with variant
B or C of said trait. Thompson's examples here include butterflies,
cod and, in the human altered environment of hospitals, drug
resistant bacteria.
Genes
More butterflies, moths, sticklebacks, mice, flax and even dogs
are employed to show how genes - proteins transcribed from DNA
- form traits in the animals carrying them.
Genomes
It talking about whole genomes, that is, whole organisms, Thompson's
examples stick to sealife and plants. He spends a great deal of
time discussing polyploidy, the duplication of genomes. Most multicellular
creatures like to think of themselves as diploid, receiving a
genome copy from each parent. The exceptions to this are
instructive.
Male ants are not diploid; they only get a single
copy. Thus all the female offspring of a queen (sisters) carry 75% of the
same genetic material whereas any female's offspring will only
have half her genes. Colony behavior makes complete sense in
this light.
On the other end are plants, which can be successfully tetraploid.
This doubling can even be repeated over multiple generations
leading to 8, 16 or more copies of the genome in a single
organism!
Last of all there is hybridization, where two separate species
join their genomes to produce offspring. You know, like Ligers
and Tigons.
Genome Coevolution
Here Thompson considers the evolutionary basis of symbiosis.
Sadly he does not mention the dangers of picking up spider suits
in distant galaxies. He does go into some detail about the human
microbiome, however, which is interesting.
Genome Conflict
Microbiota, nuclear-mitochondrial conflict, parasites, etc. all shape
an organism's genome. Perhaps the most interesting anecdote here
is that of Wolbachia, a bacteria which infects insects and can
cause infected individuals to only be able to successfully
procreate with other infected individuals, kill off males, and
other insidious things.
Adaptive Variation
At some point this book really starts to repeat itself. This is
the first chapter in which we encounter the Galapagos finches.
Rest assured. It will not be the last. Variation within a
species' population can add to the fitness of that population
by allowing for quick responses to changing circumstances, i.e.
changing your beak size when El Niño comes knocking at your
door.
Recombination & Reproduction
Sex! You'd think Thompson couldn't possibly make that subject
a bore. And you'd be wrong. Oh, and horizontal gene transfer is
probably more important than we realize.
Divergence
Thompson focuses on the variation of moths, specifically those
in the genus Greya living in the western United States.
Different species have evolved different ranges to prey on the
same plants and to prey on different plants in the same
geographic ranges. This moth and the flowers in its life will
be a recurrent theme in Thompson's discussion of coevolution.
Local Adaptation
Species randomly spread to new areas. Places distinct from
their home ranges in any number of ways can exert selective
pressure. This is the driving force behind local adaptation.
Coevolutionary Dynamics
Species sometimes evolve TOGETHER. Imagine that.
Geography
Here Thompson appears to repeat a lot of what he said in the
chapter on local adaption with different examples. I'm not sure
why this chapter is here other than to showcase all these
examples. Maybe that's how one gets their bibliography over 100
pages...
Experiments!
Since most evolution science tends to be descriptive, I found
Thompson's 13th chapter to be a special treat. Of course, because
of the finite nature of the human lifespan, these experiments
tend to focus on species that reproduce quickly like bacteria.
Ecological Speciation
Here we find a continuation of the foregoing chapters on local
adaption, but focused on when one can declare separate species.
Mainly this focuses on whether when they hybridize they can
produce viable offspring.
Reticulate Diversification
The discussion of hybrids continues, referring back to our old
friend the Greya moth among other examples. Sadly no
discussion of the Liger or Tigon was included.
Species Interactions & Radiations
Local adaption plus coevolution expounded upon in copious examples.
Webs
Coevolution as mentioned earlier highlighted binary examples,
that is, two species evolving together. Nature is rarely so
simple. In most cases there is a whole host of species interacting
together in a web.
Perceptions of Evolution
Thompson argues that scientists need to stop using euphemisms and
just say evolution. He would know. He's used every single one at
some point in this book. Still, I can't agree more! The word "evolution" is
something like "Voldemort" when communicating with the general
public. The historical conflict between scientific worldviews is,
of course, to blame, and I, like Richard Dawkins, believe we need
to firmly state which side of that argument we fall on. Say
evolution!
-- Coda --
I initially picked up Relentless Evolution because of
a review in Science
which, as I remember, portrayed it as being somewhat more
exciting. Perhaps one will find value in comparing that
analysis to the current one.
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