Bio demo: Diversity (Lessons 1, 2, 2B)

Biodiversity

is the number and variety of species and ecosystems on Earth

Scientists have various estimates for the number of species on earth

(around 8,7 million)

Number of species that have been identified

1.2 million species

What are some diverse places

Oceans, forests and rainforests

Number of new species each year

18 000 new species per year

Number of species extinct in a day

150 species go extinct each day, mostly due to deforestation

On average, mammal species live for about

1 million years

Homo sapiens (modern humans) evolved approximately

300 000 years ago in Africa

Species

is a group of organisms that can breed and produce fertile offspring under natural conditions

How do we define asexual organisms

we define a species based on their morphology

Morphology

The physical characteristics of an organism

How to write binomial nomenclature

Genus and species - uses Latin names

Both in italics, Genus is capitalized, species is not

Autotrophs

Organisms that can make their own nutrients (but most rely on other organisms for other needs)

Heterotrophs

Organisms that cannot make their own nutrients, so they must consume other organisms.

Species diversity

a measure of diversity that takes into account both the number and variety of species in an ecosystem

The greatest diversity exists in

ecosystems with many large populations

Structural diversity

The range of physical shapes and sizes of organisms within an ecosystem. It also includes the distribution and habitats of ecosystem communities

A variety of structural diversity leads to

greater biodiversity

Monocultures

farming practice of growing one crop species in a field

Monocultures reduce

biodiversity

Taxonomy

The science of identifying and classifying all organisms (living and fossils)

What does Taxonomy use

morphology, behaviour, and geographic location

Scientific names

are based on a clear set of rules, eliminating misleading common names and language issues

Ex of closely related species

European swallow and African swallow

father of modern taxonomy

Carolus Linnaeus, 18th century Swedish naturalist

naming system that we still use today

binomial nomenclature

Modern taxonomy has __ ranks

7

any specific group or unit of organisms classified together.

taxon.

Plural for taxon

taxa

acronym

**King Philip came over for good sushi

K

Kingdom

P

Phylum

C

Class

O

Order

F

Family

G

Genus

S

Species

Ex of naming

Homo sapiens

Can be shortened to

the initial of the Genus before the species name: E. coli, H. sapiens

sexual dimorphism

the difference in physical characteristics between males and females of the same species, often related to mating or reproductive functions.

ex of sexual dimorphism

peacock and peahen

Dichotomous key

a series of branching, multi-part statements used to systematically identify organisms

Classification challenges (2)

1. Dichotomous keys are great for identification but can be problematic because scientists must agree on what characteristics separate one species from another

2. Some characteristics are not easily distinguishable or different over the organisms life.

Phylogeny

the study of the evolutionary relatedness between species

Phylogenetic tree

a diagram showing evolutionary relationships between species

Nodes (points)

where branching occurs represent speciation from a common ancestor shared between species (that are found at the end of the branches)

A shorter branch indicates

a more recent common ancestor

Clade

a segment of a phylogenetic tree that includes a common ancestor and all of its descendants

The cut rule

If we cut a branch, it needs to include everything in that branch

Cladistics

the method of determining evolutionary relationships based on traits and do not indicate time frames

Derived traits

are those that have evolved that differentiate a species

e.g. of derived traits

whales are mammals without hair.

Autapomorphy

a derived trait that is unique to only one species

Synapomorphy

the presence of a derived trait in 2 or more species and their most recent common ancestor

Creating a Cladogram Steps:

1. Identify derived traits in organisms

2. Identify species that do not have derived traits

3. Connect species starting with those with the fewest derived traits.

A cladogram

a type of phylogenetic tree that uses derived traits to determine and illustrate evolutionary relatedness

Phylogenetic trees can also be built by

using fossil evidence and by comparing sequences of DNA