1.6 Adapting to the Environment (Sec 3.2 pg 61-66)

When the environment of an organism changes (biotic or abiotic factors) it must either adapt or it will not survive.

Adaptation is any genetic trait that improves an organism’s chance of surviving or reproducing

Natural selection is a process where organisms that are best suited for their environment will survive, and those that are not well-suited will die out. Natural selection is the driving force of evolution.

Organisms best suited to their environment will be best-able to breed and pass on their genes on to their offspring.

Natural selection occurs at the individual level, but affects populations. Beneficial traits (from individuals) will be passed on and become more common in the population. Natural selection occurs because of abiotic and biotic factors. Habitat features, predator-prey interactions, and food availability are all examples of selective pressures.

Natural selection video:

Some common examples of natural selection are: – Camouflage = when a species is able to blend into its background – the organism will save energy as its predator cannot see it (or vice versa if the predator’s camouflaged) see Fig.3&4 p.62

Some common examples of natural selection are: – Mimicry = when one species looks like another more dangerous, poisonous or distasteful species (see Fig 6 p.63).

Some common examples of natural selection are: – Co-evolution = when two species have adapted in response to each other. For example, herbivores may respond to available food sources with specialized beaks, teeth or digestive systems capable of digesting plant toxins; plants may respond to herbivore pressures by developing thorns, spines or tough leaves.

Biodiversity refers to the variety and variation of organisms in an ecosystem, biome, or the entire Earth. It is closely linked to primary productivity, which is the amount of energy provided by the producers in an ecosystem. A greater number of producers can support a more complex and diverse community of consumers. The greatest biodiversity on Earth occurs in tropical rainforests, where primary productivity is highest.

Extinction occurs when a species is completely gone from Earth, or when so few individuals remain that reproduction is not possible.

Extirpation refers to a phenomenon of local extinction; the species no longer exists in one specific area, but still occurs in other parts of the world.

Keystone species are species whose presence plays a crucial role in an ecosystem. If these species are eliminated from an ecosystem, there are serious and dramatic effects.

Sea otters are an example of a keystone species in Pacific marine ecosystems. They keep bottom-feeding sea invertebrate populations (e.g. sea urchins) in check, which ensures that kelp forests remain healthy. If sea otters didn’t keep sea urchin populations in check, they would eat too much of the kelp forest. Sea kelp forests are incredibly important habitats for juvenile fish, and many other organisms (they provide nursing grounds, shelter, and food).

Sea otter video: WA WA