Page 15 - 2022-bfw-morris-1e

a. in FIGURE 0.3. And it is why many bacteria and other
disease- causing microorganisms have stopped responding to
antibiotics, which is becoming a public health crisis. Life has
©2022 BFW Publishers. PAGES NOT FINAL. For review purposes only - do not post.
been shaped by evolution since its origin, and the capac-
ity for Darwinian evolution may be life’s most fundamental
property.
The concept of natural selection was in part inspired by
observing strong competition for survival and reproduction.
For example, among animals, individuals often compete
for food. In a Canada lynx population, the fastest and most
skilled hunters are more likely to succeed in catching hares,
b. and therefore surviving and reproducing. Slower and less
skilled Canada lynx are more likely to perish before they can
reproduce. If the animals with better hunting skills repro-
duce more and have more viable offspring, their offspring
will predominate in the next generation.
And just as natural selection has shaped predators, it has
also shaped prey. Predator–prey interactions are important
in every habitat on Earth. After all, every living animal can
be classified as either “predator” or “prey”—and often both
labels apply. The skills that a predator needs to hunt its prey
and that its prey needs to escape depend in large part on

FIGURE 0.2 Unity and diversity in ants
All ants have common features, such as their segmented bodies and
six legs. They also display considerable diversity, as evidenced by
the shapes and sizes of their heads, mandibles (jaws), and abdomens
(hindmost section). (a) This fire ant (Solenopsis invicta) is red and known
for its painful sting. (b) This Costa Rican army ant (Eciton burchellii) has
large mandibles and hunts in large groups. Photos: (a) Satrio Adi/EyeEm/Getty
Images; (b) John Mason/ARDEA

smallest single-celled organisms to the great Sequoia trees
and the largest animal ever, the 150-ton blue whale.
Evolution occurs by several different mechanisms that will
be discussed in detail in Unit 7. Of these, perhaps the most sig-
nificant is a process first described in the nineteenth century by
Charles Darwin and Alfred Russel Wallace. Both of these natu-
ralists suggested that species change over time by a process called
natural selection. Natural selection is a mechanism of evolution
in which some individuals survive and reproduce more than
others in a particular environment as a result of variation among
individuals that can be passed on to the next generation.
As Darwin recognized, farmers have used a princi-
ple similar to natural selection for thousands of years to FIGURE 0.3 Dog breeds
develop crops, such as wheat, corn, cabbage, and broccoli. Dog breeders use a process similar to natural selection to develop
It is how people around the world have developed breeds many different breeds of dogs, such as this husky and terrier. Photo: © Rob
of horses, pigeons, cats, and dogs, like the two shown Brodman 2011

MODULE 0 IntroductIon 3

©2022 BFW Publishers. PAGES NOT FINAL. For review purposes only - do not post.

02_morrisapbiology1e_11331_Unit1_Mod0_01-19_3pp.indd 3 10/04/21 9:09 AM