What are six examples of natural selection?

Answer 1

One classic but hypothetical example is Daisyworld. In this hypothetical model, we envision a planet inhabited by a single species of life, a single population of daisies. These come in two variants: black daisies and white. The colour is a trait that is passed on genetically to offspring. In the model, that star at which the planet revolves is variant, increasing or decreasing in intensity, changing the amount of light/heat the planet is exposed to. Black daisies will absorb more sunlight, increasing temperatures at the planet surface, while white daisies reflect more sunlight, cooling the planet. Theoretically, increasing temperatures should make things uncomfortable for the black daisies, who heat up faster because of their colour, relative to the white daisies, so that when solar luminosity increases, white daisies gain a reproductive advantage over the black daisies.

A similar example but from real life is the evolution of the peppered moth during and after the industrial revolution. Initially, lighter moths and darker moths were in equilibrium, but as the industrial revolution caused soot to stain the surfaces on which moths frequently settle, and predators could more easily distinguish the lighter moths against the darkening surfaces, darker moths gained a reproductive advantage, as they more often survived predation.

Four more findings are:

Herrel, 2008, Rapid large-scale evolutionary divergence in morphology and performance associated with exploitation of a different dietary resource.

This paper describes how in a few short decades a population of lizards transported to a different environment gained different morphological features by adapting to its new habitat.

Rolshausen, 2009, Contemporary evolution of reproductive isolation and phenotypic divergence in sympatry along a migratory divide.

This paper describes how the interaction between migratory flocks and human settlements is causing a speciation event to occur between flocks that migrate along routes including cities, and those migrating away from cities.

Lenski, 1989, Long-Term Experimental Evolution in Escherichia coli. I. Adaptation and Divergence During 2,000 Generations.

This paper describes morphological changes and associated increased in fitness during the experimental evolution of E. coli populations.

Byrne, 1999, Culex pipiens in London Underground tunnels: differentiation between surface and subterranean populations.

Describes the divergence between above-ground populations of mosquito and populations living in the London Underground, leading to the emergence of a new species.

Answer 2

1. In a population of giraffes, those with longer necks are better able to reach leaves on tall trees for food, increasing their chances of survival and reproduction. Over time, the population evolves to have longer necks.

2. In a population of insects, individuals with an inherent resistance to a certain pesticide have a higher chance of surviving when exposed to that pesticide. As a result, the population becomes more resistant to the pesticide over generations.

3. In a population of birds, those with better camouflage are less likely to be seen by predators, increasing their chances of survival. This results in the evolution of better camouflaged birds in that population.

4. In a population of bacteria, individuals that have developed resistance to antibiotics have a survival advantage when exposed to those antibiotics. Over time, the population becomes dominated by antibiotic-resistant bacteria.

5. In a population of fish, individuals that have a faster swimming speed are better able to evade predators, increasing their chances of survival and reproduction. This leads to the evolution of faster swimming fish in the population.

6. In a population of plants, individuals that produce more seeds are more likely to have their genes passed on to the next generation. This selects for plants that have a higher reproductive output and may lead to the evolution of plants with more abundant seed production.