Evolutionary arms race

Cheetahs have evolved faster running speeds to help them catch prey

An evolutionary arms race is when two species (or populations) are so linked that a change in one indirectly causes a change in the other. It is a metaphor drawn from the so-called arms race between the West and the Soviet Union, after the World War II. Evolutionary arms races are a kind of coevolution.

Examples

Predator-prey

Predator–prey evolution is the classic example. If a predator gains a new advantage, the prey must answer with a new defense.

Conifers are one example. They grew tall, to some extent out of the reach of sauropod dinosaurs. Dinosaurs grew taller and continued eating the conifers.

Gazelles and cheetahs both run very fast, which helps them catch prey. Both have continued to evolve changes which increase their running speed and thus their hunting abilities. This is another example of predator-prey evolution.

The rough-skinned newt and the garter snake interact to impact toxin resistance, according to a well-researched case study. Where the two species live together, the newt produces more toxin, and the snake has evolved to resist it; where they live separately the newt toxin is milder, and the snake has little resistance. The snakes pay a price for their resistance: their digestion and body metabolism is slower than related species. According to one source: "Really resistant snakes have slower crawl speeds than snakes with little or no resistance".

Parasite-host

Parasite–host evolution is another classic. As a host species splits into two, so do its parasites. And when the host immune system defends against the parasites, so they adapt and survive.

Sexual selection

Sexual selection can be a kind of evolutionary arms race.

Female mating preferences were responsible for the evolution of male secondary sex characteristics. Selection is between males in species where female choice is the pairing method.[clarification needed]

Sexual conflict between breeding partners is quite common. The basic interests of the male and female can be quite different, and each develops adaptations to get the best 'deal' in terms of offspring. Males: their interest is to mate with a large number of completely faithful females, thus spreading their genes widely in the population. Females: Their interest is to mate with a large number of fit males, thus producing a large number of fit and varied offspring.[better source needed]

References

  1. ↑ In the sense that, the selection pressure on the second partner changes, and counters the change in the first partner.
  2. ↑ Bakker, Robert T. 1986. The dinosaur heresies: new theories unlocking the mystery of the dinosaurs and their extinction. Morrow, New York. Chapter 9 When dinosaurs invented flowers. p181 "The warfare between plants and herbivores...".
  3. ↑ Science Daily
  4. ↑ Garter snake info
  5. ↑ Price, Peter W. 1980. Parasites. Princeton University Press, Princeton N.J. p34: "The stepwise coevolutionary process results in extreme specialization and complex defense mechanisms".
  6. ↑ Andersson M 1994. Sexual selection. Princeton Univ Press, Princeton, NJ.
  7. ↑ Arnqvist G. and Rowe L. 2005. Sexual conflict. Princeton University Press, Princeton New Jersey
  8. ↑ Schilthuizen, Menno 2001. Frogs, flies and dandelions: the making of species. Oxford University Press, p92. ISBN 019850392X
  9. ↑ Crudgington H. & Siva-Jothy M.T. 2000. Genital damage, kicking and early death. Nature. 407: 855-856.