Definitions
Species are defined by similar morphological characteristics
Morphological Definition
An exception to the biological definition
- Hybrids
- Single Celled Organisms
(How so?)
SLIDE 8 - SI SESSION 4/18/2024
HARE VS. RABBIT
They are two different species!
Hares are larger, faster, and have longer ears + legs.
Rabbits are smaller, fluffier, and overall "cuter".
They even have different diets and social patterns.
Known as the father of modern taxonomy
Carl Linnaeus
What is one structural difference between DNA and RNA?
Double Stranded vs. Single Stranded
T for U
Deoxyribose vs. Ribose sugars
Etc.
Groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups.
Biological Definition
An Exception to the Morphological Definition
- Species that look similar but aren't closely related at all!
- Individuals within the species may vary wildly in appearance with each other.
SLIDE 9 - SI SESSION 4/18/2024
These are two different species! The one on the left is the American alligator, and the one on the right is the crocodile.
A quote he wrote follows, "It all comes, I believe, from trying to define the undefinable".
Charles Darwin
What is a niche? Give an example from class that we used to discuss the roles that niches have in biodiversity.
The role an organism plays/has in an environment - can be several different things.
A natural taxon in classification in which members of the group share an invariant generalized or idealized pattern.
Taxonomic Definition
A critique of the Evolutionary Definition
- Cant observe a lineage itself... where do you draw the line?
SLIDE 10 - SI SESSION 4/18/2024
WEASEL VS. STOAT
They are different species! Stoats are bigger and have long tails with fuzzy black tips - and weasels have a shorter tail that are the same color as their body. Stoats turn white in the winter - and they have different patterns of movement.
Tenrecs and Hedgehogs are an example of the criticism to which definition of species? Why?
Morphological - look similar but are actually distantly related!
A reason that a harmful mutation may continue to persist in a population!
- Homozygous recessive ... carriers!
Evolutionary Definition
A criticism of the Ecological Definition of A species
- Creates too many splits between what are functionally identical populations.
SLIDE 10 - SI SESSION 4/18/2024
The one on the left is a Dorper sheep, and the one on the right is a Merino sheep! These two - while looking different, are two breeds of the same species!
Which bird showed the importance of identifying the differences between species? And why?
The Hooded Pitohui - It's poisonous!
What is the difference between genetic drift and gene flow?
Drift vs. Migration
Genes are randomly fixed in a population vs. genes are introduced into a population.
A genetically distinct population which is genotypically adapted for a specific set of environmental conditions.
Ecological Definition
Criticisms of the genetic definition of a species.
- Threshold of genetic similarity to split species, but who picks this amount?
- Cannot assess species divergence based through time/fossil records.
SLIDE 11 - SI SESSION 4/18/2024
They are the same species! They are both part of the Anas Platyrhynchos species - also known as mallards! Mallards are sexually dimorphic - meaning that males and females look different from each other.
Was the subject of Professor Peterson's PHD thesis/research!
The Black Rail
Explain what parsimony is and what it is used for!
Phylogenetic trees - are used to determine which tree is the most likely to have occurred (the least amount of trait changes). Simplest = best.