Chapter 1: Diversity of Living Things

Biodiversity

The variety and number of life forms on Earth.

How can we develop a better understanding of these living things?

By observing physical characteristics or features and the molecular composition of their genetic material (Ex. Number of chromosomes, mutations…)

Species

Organisms able to breed freely with each other under natural conditions.

Hybridization

Plants often cross breed; organisms that breed asexually.

What is often used to identify species?

Morphology or physical characteristics

Individual Variability

Within a species, there can be subtle differences within traits. This genetic

diversity is important to a species’ ability to survive and adapt to changing

conditions/environments (ex. Evolution).

Diversity of Interactions

Many different species exist in each ecosystem and depend on one another for survival. (Ex. Heterotroph vs. autotroph).

Heterotroph

An organism that obtains energy-rich nutrients by consuming living or dead organisms.

Autotroph

An organism that uses sources of energy to produce nutrients from water, gases, and/or minerals.

Food Supply

Complex relationships exist between species and their food. (Ex. boneworms feeding on the bones of dead whales that sink to the bottom of the ocean.)

Protection

Many species depend on others for shelter and protection. (Ex. hermit crabs use the shells of dead snails for a protective home.)

Transportation

Many species move from place to place with the help of another species. (Ex. some flower mites climb onto the bills of hummingbirds moving from flower to flower feeding on nectar.)

Reproduction

Many species depend on other species for their own successful reproduction. (Ex. many bird species build their nests in the abandoned tree cavities made by woodpeckers for their own nests.)

Hygiene

Some species help maintain the health of another species. (Ex. coral reefs have “cleaning stations” where large fish come to have external parasites removed by small fish and shrimp.)

Digestion

Species living within digestive tracts are essential for the digestion of food. (Ex. bacteria living in the large intestines of humans produce vitamins that are absorbed into the circulatory system.)

Structural Diversity

The range of physical shapes, sizes and distribution of individuals (abiotic factors). It also allows for microhabitats that support many different species.

Species Diversity

A measure of diversity that takes into account the quantity of each species present, as well as the variety of different species present.

Genetic Diversity

The genetic variability among organisms; usually referring to individuals of the same species.

Evolutionary Change

A change that occurs in an entire population; usually occurs over a long period of time.

Why do we need a classification system for living things?

1. To understand the behaviours and characteristics of living things.

2. To understand the dangers and benefits of living things (ex. The death angel is a poisonous mushroom).

3. To understand the evolutionary lines of species.

Biological Classification

The systematic grouping of organisms into biological categories based on physical and evolutionary relationships.

Taxonomy

Science of identifying and classifying all organisms. Very challenging due to the millions of species on Earth and those species that are extinct.

Carl Linnaeus (1707-1778)

• Father of taxonomy

• Introduced a system to classify living organisms based on morphology

Traditional Taxonomic Levels

Linnaeus further grouped species into taxonomic levels (based on shared characteristics)

The Seven Taxonomic Levels

1. Kingdom

2. Phylum

3. Class

4. Order

5. Family

6. Genus

7. Species

The Seven Taxonomic Levels for Humans

1. Animalia

2. Chordata

3. Mammalia

4. Primates

5. Hominidae

6. Homo

7. Homo sapiens

How are similiar species grouped together?

Similar species are grouped together into genera (genus), similar genera into family, families into orders…etc.

Dichotomous Keys

• Are used to help identify living organisms. It is based on morphological observations.

• The key narrows down the characteristics into one possible species classification

• It is divided into subsets that provide 2 defining options.

Phylogeny

Study of evolutionary relationships between and among species.

Phylogenetic tree

Diagram depicting the evolutionary relationships between different species or groups.

Clades

A taxonomic group that includes a single common ancestor and all its descendants