Biology of Populations and Communities, BioS 101
Lecture 1
Prof. Dennis Nyberg
3452 SES
Speaker Notes:
Be sure to read the set of slides that describes course Information and Rules.
Reading Assignment
-
For today’s lecture read Chapter 1 in Freeman’s Biological Science, 3rd Ed.
-
Check Your Understanding (p 11) Do it!
-
The glossary (blue edged) of the textbook should be consulted when unfamiliar words are encountered.
Speaker Notes:
What is a species?
-
Species is a "type".
-
Types are based on shared similarity within type and shared differences among types.
-
Which similarities are more judged more fundamental to separate biological species has changed quite a bit in last couple hundred years.
Speaker Notes:
What is a population? A biological community is a set of populations of different species living together in the same place (interacting).
What criteria are used to group & distinguish individuals & species?
-
Behavioral
-
Morphological
-
Who mates with whom –breeding patterns
-
Molecular sequence similarity
-
Phylogeny = the ‘tree of life’
-
Speaker Notes:
Set up the idea of measuring differences.
Grouping and Separating
-
Early in biology morphological features were most important in distinguishing species, but …..
-
Changes within life of an individual are NOT useful in separating biological species.
-
Individual continuity is more sensible than morphology.
Speaker Notes:
Ask for examples of dramatic morphological changes in individuals during their life.
Species conceptions
-
Individuals are born, develop and grow old. They change but remain the same person. The continuity of life idea applies to populations and species as well.
-
Males and females which mate and produce offspring, even those that may look quite different, share those offspring. They should be the same species, because they share a future.
Speaker Notes:
Ideas about ‘species’ have changed a lot
Continuity of life
-
Each of you has parents and grandparents, etc. Life has a continuity with the past. All living entities are derived from living things. There is NO spontaneous generation of living individuals from non-living things.
-
Continuity naturally leads to a ‘tree of life’ (see p. 10) which unites increasingly different species as one goes back in time.
Speaker Notes:
In lecture illustrate a pedigree and show how it relates to the simple tree of life.
Biologists’ Species Definition
-
A species is the collection of individuals that are united by sharing of genes in the recent past and potentially sharing genes in the future.
-
In past practice, most species names are based on morphological similarities and differences.
Speaker Notes:
The continuity is established by transmission of genes to offspring. Biological information is stored in genes.
Tree of life = phylogeny
-
Currently the ‘tree of life’ is based primarily on similarities in DNA sequences.
-
DNA sequences reproduce mostly identical copies but accumulate changes with time. Sequence similarity measures distance to ancestral sequence (common ancestor).
-
The ‘tree of life’ is made by counting differences between DNA sequences.
Speaker Notes:
Problem
-
On page 11 there is a “Check your understanding” box. For each pair of species (A/B, A/C & B/C), count the differences between the sequences given.
-
Which pair of species is most similar to one another?
-
How can the differences be used to construct a relationship (tree) of the types?
Speaker Notes:
Do this problem in lecture.
Talk about the similarity of 1) green triangle, 2) red triangle, & 3) red circle.
Phylogenetic Trees
-
Connecting species hierarchically according to closeness (similarity) leads to a tree like pattern (Fig. 1.9)
-
The branching pattern shows the origin of each species (group) named. The pattern of origin is known as the phylogeny.
-
“Tree of Life” implies a single origin for all branches of life.
Speaker Notes:
Conceptual Review Question #2 on p17
Common Names
-
Common Names of species have a communal meaning and are ‘words’ of the language.
-
Wolf
-
Black-eyed susan
-
Sweet black-eyed susan
-
-
They may be one word or many.
Speaker Notes:
Common names have no regular structure in terms of number of modifiers or order of terms.
Cover some examples in class.
Scientific Name
-
Biologists have devised a convention with structure for naming species.
-
Each scientific species name has two parts.
-
The first part is the genus, it names a bigger group than just the species (nested groups).
-
the second part is the specific epithet –it identifies a subset of the genus.
-
-
A third part may identify a group called a subspecies or a variety that is distinct within the species.
-
Speaker Notes:
Cover the conventions in lecture, including varieties and subspecies.
Scientific Name of humans
-
Homo sapiens
-
Homo is the genus (genera is the plural)
-
The genus is always capitalized. It may be abbreviated by its first letter, after it is first spelled out, i.e., H. sapiens.
-
-
sapiens is the specific epithet.
-
The specific epithet never appears alone and is never capitalized.
-
Speaker Notes:
In the genus Homo most problems don’t involve distinguishing people from contemporary species, but rather concern distinguishing fossil finds from other fossils and from modern man.
More Naming Conventions
-
Quercus bicolor Swamp white oak
-
Both genus & specific epithet should be italicized (underlined in handwritten documents).
-
Third parts, also italicized, are allowed for subspecies
-
Silphium integrifolium integrifolium
-
Silphium integrifolium deamii
-
-
Speaker Notes:
Quercus is the genus name for ‘oak’. All local oak trees are in the genus Quercus. There are two major groups of oaks –the white oaks and the red/black oaks. Both groups have many species. The two groups within the genus could be used to split the genus into two genera, but biologists think there is enough similarity among the oaks to keep all species in the genus Quercus.
A Hierarchical Classification has been used to organize species
-
“Hierarchical” is also called “nested”.
-
Each name used a taxonomic level is completely within the group at more inclusive levels.
-
Each member of the genus Homo is a member of the Hominidae family, the Primate order, the Mammal class, and the Chordata phylum. (Fig. 1.5)
-
Speaker Notes:
Nesting is illustrated on slide 16.
Classification Hierarchy (animal)
-
From most inclusive down to most specific
-
Phylum
-
Class
-
Order
-
Family
-
Genus
-
Species
-
-
Each level can be called a taxon (plural taxa)
Speaker Notes:
This scheme applies to animals.
EVOLUTION
-
The idea of continuity with change (=evolution) permeates biology.
-
Our concept of natural selection provides the mechanism which produces adaptive change, but most change of DNA sequences can not be shown to improve function.
-
The world is dynamic = always changing, but most change makes no difference.
Speaker Notes:
The idea of Intelligent Design suggests a world where types do not change. One in which it is the original or nothing.
VOCABULARY
-
Species
-
Genus
-
Specific epithet
-
Phylogeny
-
“Tree of life”
-
Scientific name
-
Continuity of life
-
Hierarchical = nested
-
DNA sequence
Speaker Notes:
Talk about your conceptions of these ideas/words with your classmates. Then talk to the staff to improve your understanding.