Lecture 21
How is diversification measured?
Speciation (new species) - extinction (species dead)
Remember why its important to give specific taxa
names
Taxonomy = organizes evolution, through observing, documenting and testing hypotheses; fundamental to biodiversity
Grouping into taxa (morph. + evol.)> ranking into diff taxa (taxon into rank) > naming for meaningful organization
The importance of taxonomy:
-understand biodiversity
-chemical properties for medicine/poison
-identify food crop
What is a monophyletic, polyphyletic and paraphyletic group?
monophyletic = a group of organisms that includes a single common ancestor & ALL of its descendants.
e.g. Monocots, eudicots
polyphyletic = a set of organisms that have been grouped together based on similar characters but DO NOT share an immediate common ancestor.
paraphyletic = a classification that includes a common ancestor & SOME of its descendants.
e.g. Dicot (includes basal angiosperm & eudicots but excluding monocots)
What are the three genomes of plants? What inheritance line does each genome
follow (paternal, material, both)?
1. Mitochondria (maternal) = highly conserved gene sequence & variable in gene arrangement
2. Chloroplasts (paternal) = fairly conserved in gene sequence & arrangement
3. Nuclear = variable in gene sequence & arrangement; inherited from both parents
Learn the different ways we have classified (organize)
life on earth
1. Artificial vs Natural
a. artificial: based on a few arbitrary, specific characters (number & fusion of sexual parts by Linnaeus)
b. natural: based on "similar" or "related" groups on many characters
2. Hierarchical vs non-hierarchical
a. hierarchical: hybrids; do not necessarily reflect all the ways that evolution operates
b. non-hierarchical: ecotypes; 1 species has multiple ecotypes
3. Phenetic vs Phylogenetic
a. Phenetic: based on observable characters (phenetic similarities); computer computation into classification, arguing impossible to deduce evolutionary history based on a common ancestor
What is conservation? What are the differences btw conservation & preservation?
Conservation = Managing the natural environment so that it limits & prevents environmental degradation & destruction; protection of natural resources for proper use
Preservation = protection of buildings, objects & landscapes -> protection of nature from use
Discuss the strength of using more than one genome to for genetic studies?
(More generally, it might be useful to think about the different genomes and
think about their traits and how their use may affect genetic studies).
Depending on which genome is used, we can identify which parent gave pollen/ovule to the offspring. For example, in a hybrid species, by looking at mitochondrial genes and comparing them to the parents, we know the maternal paren that gave an ovule.
Be able to explain the strengths and weaknesses with
each classification system
1. Artificial vs Natural
Artificial: too specific
Natural: less specific than artificial, but does not solve every taxa situation since it is still based on morphological characters.
2. Hierarchical vs non-hierarchical > do not necessarily reflect evolution or common ancestors
3. Phenetic vs Phylogenetic
Phenetic weaknesses: does not reflect evolution; ignores environmental forces on morphology; ignores ecotypes; cannot use primate characters; only use shared, advanced characters; no use of unique characters
What are the things we take into consideration when we want to conserve?
Species/taxa/
hybrids -> not protected under US law
Invasive -> if it is going to become extinct in the native area, do we conserve?
Decision-making: Who decides to conserve? The land ownership & access to the resources?
Development/economy: hydroelectric dam in the Fraser Valley, mining activities in Nunavut
What are some ways in which genes can duplicate?
How does gene duplication lead to new species (trait functions)?
Gene duplication:
Polyploidy = whole genome duplication (having more than 2 sets of chromosomes) -> leads to functional redundancy (1 copy of duplicated genes serve a new function) -> new species
How does this occur?
Spontaneously at low frequency, or by the environmental pressure, or by colchicine
Learn how different types of characters, both
morphological and genetic, have been used for
classification
Morphological characters: = features possessed by an organism that are comparable & measurable
Character state = binary, multistate, continuous
Genetic characters: highly conserved chloroplast genes (rbcl) or nuclear genes (ITS of ribosomal DNA)
List a few advisory organizations for conservation in Canada.
SARA (Species at Risk Act) in 2002: Canadian Federal Protection>prevent wildlife from extinction & recovery of wildlife
COSEWIC (Committee on the Status of Endangered Wildlife in Canada): an independent, private scientific advisory> assess the status of wildlife at risk of extinction
What is the difference between an autopolyploid and allopolyploid? Is one more genetically isolated than the other? Is one more likely to give rise to new species?
Autopolyploids
-doubling chromosomes WITHIN a species; genetically identical (looking the same) to the diploid parents but reproductively isolated
-many sterile autoploids reproduce asexually (vegetative or apomictic)
-apomicts can spread in a more extreme climate than the parents
Allopolyploids
-hybrid (interspecific) polyploids with 2 distinct parental species
-fixed heterozygosity
-instant new species since allopolyploids are reproductively isolated from the parents b/c chromosomes do not segregate normally during meiosis
(e.g. diploids Tragopogon dubius (Europe) x porrifolius (US) -> sterile hybrid offspring -> fertile hybrid independently originated tetraploid Tragopogon mirus)
*has both parents' morphological characteristics but is reproductively isolated from them
-Understand what phylogenies are
-Gain a basic understanding of phylogenetic groupings
Phylogenetics = the study of the genetic history of life by grouping using molecular markers & DNA sequencing
Grouping based on genetic relationships & looking at when a certain character evolved
Parsimony = explain observations with the simplest hypothesis
Phylogeny = the evolutionary history of the development of a species;
Organisms pass down their genes by mating > finding a genetic descent in the population from the previous generation > tracing back generations > predict future such as disease resistance