Biodiversity and

Classification of

Living Things

Biological Species Concept

Recall:

Species – a population of organisms whose

members can breed freely in nature and produce

fertile offspring

Ecological, behavioural, and physical differences

normally keep two different species from

interbreeding.

Biodiversity

Biodiversity is the number and variety of species and

ecosystems on earth.

Higher biodiversity generally leads to resiliency of

the ecosystem to changes in the environment.

Keystone species are species that have a

disproportionately large effect on the ecosystem in

which they live.

The presence or absence of a keystone species

can have a dramatic impact on an ecosystem.

E.g. pesticides applied to crops can kill insects which

are responsible for pollination

Genetic Diversity

Genetic diversity - The genetic variability among

organisms – usually referring to individuals of the

same species.

Sexual reproduction results in offspring with a unique

combination of genetic information inherited from

their parents.

This variation among individuals allows populations

to adapt to environmental changes.

Species Diversity

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.

Each species contributes to the ecosystem.

A variety of species ensures that the ecosystem is

able to adapt to environmental changes.

Ecosystem Diversity

Ecosystem diversity - The diverse range of habitats,

organisms, and interactions that connect them.

This includes structural diversity which can create

microhabitats.

Larger structural diversity can support a greater

species diversity and species interactions.

E.g. food supply, protection, transportation,

reproduction, hygiene, digestion

Societal Impacts

Loss of biodiversity can impact human populations

Threatened food supply

Eliminates sources of natural medicines

Economic impact on tourism and forestry

Disruptions to biogeochemical cycles

Case Study

Honeybees have a crucial role as a pollinator.

Recent studies have shown a decline in the global

population of honeybees.

Possible causes

Pesticide use

Viral infection transmitted by parasites

Classification

Classify the following groups of organisms. What

categories could be used?

Yeast Cow Maple Tree

Bee Tiger Amoeba

Monkey Fern Corn

Butterfly Chicken Cyanobacteria

Mold Worm Hammerhead Shark

Venus Fly Trap Mushroom Blue Footed Booby

Lion Pigeon Whale

Classification

If you were to classify the organisms that cause the

following diseases, what categories could be used?

Strep throat Flu Anthrax

HIV Mad Cow Meningitis

Samonella Cold Sores Ebola

Flesh Eating Disease

West Nile E. Coli

Tuberculosis SARS Clamydia

Herpes Pink Eye Pneumonia

Tetnus Malaria Yeast Infection

Biological Classification

Classification systems are a source of information

and a tool for communication.

Defined categories show the relationships among

items.

Biological classification – The systematic grouping of

organisms into biological categories based on

physical and evolutionary relationships.

Organisms can be identified by observable characteristics morphology, behaviour, and

geographic location

Taxonomy

Taxonomy – the science of naming, identifying, and

classifying all organisms.

Binomial Nomenclature

Carl Linnaeus was a naturalist and botanist who is

considered the father of taxonomy.

He felt that each organism should have a distinct

identifying name that would help to identify it.

He grouped organisms by shared physical

characteristics and developed a naming system.

Binomial nomenclature – the formal system of

naming species whereby each species is assigned a

genus name followed by a specific name; the two

words taken together form the species name.

Taxons Linnaeus further grouped species into taxonomic levels

(taxons) based on their shared characteristics.

Kingdom

Phylum

Class

Order

Family

Genus

Species

With binomial nomenclature, the first part of the name is the genus, and the second part of the name is the species.

The first letter of the genus is capitalized, and the whole name is italicized. E.g. Escherichia coli, or E. coli

Each taxonomic rank consists of species that have

similar features.

E.g. chordata – backbone, mammalia – warm-

blooded

Taxons

Modern Classification

The classification system developed by Linnaeus

grouped organisms according to morphology.

However, this alone was not always adequate or

correct when categorizing organisms.

In 1859, Charles Darwin published The Origin of

Species which outlined his theory of evolution.

This allowed biologist to develop new methods of

classification that involves the evolutionary

relationships between organisms based on shared

ancestry.

Advances in technology have also allowed for the

inclusion of molecular data into defining ancestry.

Phylogeny

Phylogeny – the study of the evolutionary

relatedness between, and among, species.

Phylogenetic Trees

Phylogenetic tree – a diagram that reflects the

hypotheses of evolutionary relationships.

Domains

Phylogenetic relationships have led to the

development of a broader taxon known as domain.

Domain is the highest taxonomic level and there

are three domains of life – Bacteria, Archaea, and

Eukarya.

Bacteria and Archaea are microscopic and

unicellular. They are also prokaryotes - single-celled

organisms that do not contain membrane-bound

organelles.

The third domain, Eukarya, consists of eukaryotes –

organisms whose cells contain membrane-bound

organelles.

Structure Prokaryotes Eukaryotes

Genetic material Free-floating, uncoated DNA

Membrane-bound nucleus

with chromosomes of DNA

and protein

Cell division Fission or budding Mitosis

Sexual

recombinationTransfer of genes Meiosis

Tissue

developmentNone, single-celled Sometimes, if multi-cellular

Respiration Not all require oxygen Almost all require oxygen

Size Microscopic Mostly macroscopic

Energy

productionFree-floating enzymes

Enzymes in mitochondria or

chloroplasts

Flagella Simple Complex