Name 3 "Big Ideas" from our last notebook lecture: * * * 1
WDYR? Of the following organisms, which is the closest relative of the "Snowy Owl" (Bubo scandiacus)? a) barn owl (Tyto alba) b) saw whet owl (Aegolius acadicus) c) great horned owl (Bubo virginianus) d) burrowing owl (Athene cunicularia) 2
1.2 Determining How Species Are Related Phylogenetic Tree 3
1.2 Learning Goals To understand that scientists use evidence from anatomy, physiology, and DNA in order to connect the evolutionary relationships between organisms Understand, create and apply information from a Phlylogenetic Tree in order to draw a Cladogram to demonstrate the evolutionary relationships between organisms 4
A) Shared Evolutionary History ancestor: an organism(s) from which other groups of organisms are descended Main goal of modern taxonomy is to determine the shared evolutionary history of groups of organisms Biologists assume that the greater the shared evolutionary history between organisms, the more closely related they are This can be done by comparing species living today with groups of species that lived in the past Scientists use evidence from several types of information to determine relatedness among organisms: Anatomy, Physiology, DNA 5
1. Evidence from Anatomy The study of the structure of organisms Uses anatomical evidence from living species to determine relationships among organisms Ex: similar bone structure may indicate a shared evolutionary history text p18 over millions of years, the size and the proportions of the bones have been modified for different purposes (swimming, flying, running, grasping) however the overall arrangement and similarities indicate a shared evolutionary history 6
2. Evidence from Physiology The study of the functioning of organisms both physical and chemical focuses on biochemistry of organisms and how they make their proteins Whether as enzymes, or as parts of cells and tissues, an organism's proteins are determined by the organism's genes text p19 Example: by analyzing insulin and blood proteins, it was discovered that the horseshoe crab is more closely related to spiders than to other shelled species 7
3. Evidence from DNA Genetic analysis Genes are sections of DNA made up of long chains of nucleotides Genes code instructions for making proteins The degree of genetic similarity is determined 8
Ch 1.2 Determining How Species Are Related.notebook The more genes and genetic sequences two individuals have in common, the more closely they are related Chimpanzees are our closest relatives...we have 98% of our genes in common with them! 9
B) Phylogenetic Trees and Cladograms phylogeny evolutionary history of an organism cladogram simplified branching diagram that has the same information as a Phylogenetic Tree 10
What's the link? "Since it is thought that all species evolve from a common ancestor, then all members of a group must have evolved through a series of events in which ancestral species gave rise to new species, each giving rise to a new lineage." 11
Phylogeny can be more easily illustrated using a " Cladogram" Branches represent a sequence of events with progressive evolutionary traits Root represents the common ancestor The "cladogram" groups organisms based on their phylogeny or evolutionary history Closely related organisms are classified together with all other organisms that share a common ancestor These related organisms are placed in the same monophyletic group called a clade 12
Examine the evolutionary relationship among major groups of vertebrates 13
Point in time when an ancestral group split, resulting in 2 species One species gave rise to the lineage of ray finned fish The other species became ancestral to all other new groups to come Events at A 14
Point in time when ancestral species split into 2 main lineages, one being mammals... Events at C 15
Inference Birds and crocodiles are more closely related (both from E) than crocodiles and turtles (E, D). Mammals are as closely related to turtles as they are to birds. All three organisms come from the common ancestor C. 16
Cladograms also show the sequence in which species split A is more ancient than B, which is more ancient than C, etc... 17
How to Draw a Cladogram: 1. Draw a large V 2. Draw branches from the base to represent each organism 3. The base represents progressive traits from the most ancient ancestor to the most recent organism 4. The outgroup is placed first at the top of the first branch 5. The evolution of derived characteristics occurs along the base between nodes 6. Speciation events (which gives rise to new lineages) occur at the nodes 18
When constructing a cladogram, refer to two groups: Ingroup Species or groups chosen for study Outgroup Similar but distantly related group Note... Each member of the ingroup is compared to the outgroup Since the outgroup is distantly related, any trait shared by ingroup members (and not found in the outgroup) is called a "shared derived trait" The more closely related organisms are, the more genetic similarities they have 19
How to draw a Cladogram! Video #1: https://www.youtube.com/watch?v=e4yq41eyphc Video #2: https://www.youtube.com/watch? v=c58k8wnul1y 20
Let's try one together... Sample Cladogram #1: Characteristic Bacterial Cell Shark Bullfrog Kangaroo Human vertebrae + + + + 2 pairs of limbs + + + mammary glands + + placenta + 21
Sample cladogram #2 22
Answer: outgroup ingroup lamprey pike Questions?? lungfish turtle A bony wolf shell jaws gorilla lungs hair human grasping hands a) Which 2 species are most closely related? b) Are pike more closely related to lungfish or to gorillas? c) Which of the derived traits came into existence before the bony shell? B C D E F derived traits 23
Importance of Classification to the Real World Scientists looking for new pharmaceutical drugs and hormones can narrow search to organisms related to already known species that produce valuable proteins or chemicals Scientists can more easily trace the transmission of diseases Scientists continue to develop agricultural GMO's Scientists discover new species, or re classify existing organisms as a new separate species in order to implement protective conservation laws against poaching 24
Dr. Paul Hebert, a Geneticist at the University of Guelph, has gone "techy" with classification! He is assigning coloured computer bar codes for all living organisms in the world! The more closely the "bar codes" look alike, the more closely related the species are! 25
Review & Learning Check Read p 17 21 Answer Q's 2,5,6,7, 8,9a p23 26