English for

Figure 63.
Both the northern and Mexican spotted owls live in geographically distinct regions with unique 
climatic conditions and ecological systems. The owl is an illustration of early speciation
41
.
 
Additionally, researchers have discovered that speciation is more likely to occur the further apart two 
groups that were once members of the same species. It makes sense that this would be the case since distant 
locations would likely have fewer environmental factors in common than those that are close by. Take the two 
40
Fowler, S.,Roush, R. & Wise, J. (2017) 
Concepts in Biology, 
Chapter 11, -Pp. 262-263. OpenStax, 
https://openstax.org/details/books/concepts-biology
 
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(credit “northern spotted owl”: modification of work by John and Karen Hollingsworth, USFWS; credit “Mexican 
spotted owl”: modification of work by Bill Radke, USFWS)

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owls as an example. The climate is cooler in the north than it is in the south, the other species of organisms in 
each ecosystem differ, as do their behaviors and habits. Additionally, the southern owls' hunting techniques 
and prey preferences differ from those of the northern owls. These variations may result in evolved differences 
in the owls, and unless gene flow between the populations is restored, speciation will probably happen over 
time. 
Sometimes a population of a single species disperses over a large area, with each individual finding a 
unique niche or isolated habitat. Adaptive radiation is the process of multiple speciation events arising from a 
single species over time as a result of the various demands of their new lifestyles. Numerous adaptations 
develop from a single point of origin, spreading the species outward into numerous new ones. Because each 
island in an archipelago is surrounded by water, creating geographic isolation for many organisms, 
environments like the Hawaiian Islands make an ideal setting for adaptive radiation events (Figure 64). 
Adaptive radiation is demonstrated by the Hawaiian honeycreeper, among other examples. Numerous species, 
including the eight depicted in Figure 64, have evolved from a single species, known as the founder species.
Figure 64.
Adaptive radiation is illustrated by honeycreeper birds. Many different bird species with unique 
traits have evolved from one original species. 
Figure 64 illustrates the variations in the species' beaks. Natural selection based on particular food 
sources in each new habitat changed the genetic variation of beaks, which resulted in the evolution of a 
different beak suited to the particular food source. Birds that eat fruit and seeds have thicker, more powerful 
beaks that are better suited for cracking hard nuts. The long beaks of the nectar-eating birds are used to dunk 
into flowers and extract nectar. The sword-like beaks of the insect-eating birds are ideal for piercing and 
impaling insects. Another extensively researched instance of adaptive radiation in an archipelago is Darwin's 
finches
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.
 
42
: Fowler, S.,Roush, R. & Wise, J. (2017) 
Concepts in Biology, 
Chapter 11, -Pp. 263-264 OpenStax, 
https://openstax.org/details/books/concepts-biology
, p)

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