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A primary reason for the evolution of all that exists on this planet is caused by natural selection. Natural selection, a theory that was scientifically experimented and made acceptable by a man named Charles Darwin explained how species evolved and changed over time. According to Darwin all organisms in their species group have some form of variation. Due to this difference in variation he concluded that the organisms that were best fit to their environment would survive and live to reproduce and pass on their genes to their offspring. Those small variations would then extend to the rest of the population throughout time as the genes of those less fit would die off or become less frequent. The way that Darwin came to this realization was by observing the birds of the Galápagos Islands also known as the Galápagos finches. He came to realize through observation that the birds that had beaks better suited to the food available in the environment were more competent to mate than others, like those birds who had beak shapes that were better suited to obtaining nectar from flowers or eating hard seeds. These birds that held an advantage over others of the same species is a key component to understanding how nature helps the best-adapted varieties to survive and reproduce.

Another key component in understanding how evolution works in the web of life is coevolution. Coevolution describes the relationship in which different species affect each other’s evolution. This form of evolution is very likely to happen in nature, especially when there is a close relationship between species. Keep this in mind when thinking about the roles that hummingbirds have with the flowers that they obtain nectar from. This is a big component to their bill-l...

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...s DNA (Wang et al. 2014)

Hummingbirds from the family Trochilidae have gone through a huge wave of evolutionary divergence with more than three hundred thirty species that are classified into over one hundred genera, making hummingbirds one of the most remarkable diverse birds. This reflects the amount of morphological and physiological adaptations that have correlated with nectar-feeding attributes (Bleiweiss et al. 1997).

Due to the wide range in hummingbird adaptations from years and years of evolution, there is now noticeable sexual dimorphism present between male and female hummingbirds, mostly in non-hermit species that reside in the Andean and orogenies. Sexual dimorphism is a phenotypic difference between males and females. One of the phenotypic differences between female and male hummingbirds is bill length associated with plumage and breeding behaviors.