Speciation Creation of Unique Gene Pools I Introduction
- Slides: 48
Speciation Creation of Unique Gene Pools
I. Introduction • A. Microevolution vs. macroevolution – 1. microevolution • a. Definition • b. Example • c. Importance in evolutionary process • d. Can be seen • e. Measurable • f. Natural selection
2. macroevolution • a. evolution or creation of new taxonomic groups • b. Novel innovations • c. New ways of making living • d. Branching of phylogenetic tree • e. Evolution of coelom • f. May not occur by natural selection • g. Harder to understand
B. Speciation events may drive macroevolution • 1. New species may be first of a new grade or branch • 2. Two modes of speciation observed in fossil record – a. anagenesis – b. cladogenesis
C. Anagenesis-gradualism • 1. species seem to slowly gradually change • 2. from one springs another • 3. driven by natural selection • 4. not as often seen in the fossil record
D. Cladogenesis • • 1. branching pattern 2. rapid speciation event 3. punctuated equilibrium 4. supported by many records in fossil
II. What is a species? • A. Morphological species concept – – 1. 2. 3. 4. places specimen together or separates them on structural basis convenient when working in a lab fossil organisms that don’t come into contact
B. Biological species concept • 1. definition • 2. particularly good definition for population genetics • 3. speciation occurs when two gene pools become separate and distinct
III. How does speciation occur A. Allopatric speciation 1. barrier 2. gene flow interupted 3. differences accumulate 4. when become sympatric?
5. Generalizations • a. Requires a lot of time generally • b. Most often occurs in small populations • c. What is barrier to one may not be barrier to another • d. Adaptive radiation example of allopatric speciation • e. End point of speciation event is hard to agree to • f. Most common?
B. Parapatric speciation • 1. two populations sort of separated • 2. experience different selection pressures at edges of range • 3. differences accumulate despite gene flow • 4. gene flow becomes impossible
C. Sympatric speciation • 1. most commonly seen in plants • 2. common barrier to hybridization is meiotic failure of hybrid – a. Two distinct sets of chromosomes – b. No homologous pairs – c. What happens at prophase I of meiosis
3. Polyploidy occurs commonly in plants a. Haploid b. Diploid c. Polyploid d. Generally leads to sterility • e. But in plants • •
4. Allopolyploidy
4. New species form this way in plants because they self pollinate
5. Very uncommon in animals-cichlids
6. Parasites and hosts-apple maggot fly
Flies tend to stay on host
V. Pre and postzygotic barriers to hybrid formation • A. Natural selection operates to maintain separate gene pools when speciation has occurred • 1. Imagine disruptive selection • 2. Specializations occur • 3. Overlap after speciation event • 4. Potential interbreeding • 5. Parental species have specialized • 6. Hybrids dilute the specializations • 7. Natural selection would come down hard on the dilution
B. Prezygotic barriers • 1. Habitat isolation
2. Behavioral isolation
Spotted Newts
Spermatophore and red eft
3. Temporal isolation
4. Vocalizations Eleutherodactylus coqui
5. Mechanical Isolation
Kangaroo penis types
Adapters?
C. Postzygotic barriers to hybridization • 1. hybrid inviability • 2. hybrid sterility • 3. hybrid breakdown-F 2 are sterile
D. Thought questions • 1. Do prezygotic or postzygotic barriers to hybrid formation form first? • 2. Which of these two mechanisms is favored by natural selection? • 3. Which of these two methods is more cost effective?
VI. Potential forces behind macroevolutionary change • A. Chance – 1. cannot be preadapted to a disaster – 2. meteorite implosion will wipe out all but lucky few – 3. who survives can direct future evolutionary paths
B. Macromutations • 1. translocations
2. Inversions
3. Chromosomal duplications
C. Segmentation genes • 1. ancestral animals were one continuous body piece • 2. the evolution of segmentation genes produced a branch in the tree of life • 3. segmentation of body parts allows specializations to occur in different regions of the body • 4. feeding structures and locomotion appendages
D. Homeotic genes • 1. specify developmental plan for each segment • 2. mutations can cause one body part to be replaced by a second • 3. leg growing from head
E. Hox genes control number of appendages • 1. ancestral fruit fly had four wings • 2. more economical and faster to fly with two wings • 3. mutation in Hox genes can cause backward jump • 4. devolution
F. Allometric growth • 1. varied growth rates for different parts of the body during development
2. Mutation in the genes which govern allometric growth • Might produce chances for rapid evolutionary chanage • Growth rates altered, drastic changes in shape • May or may not be adaptive
Ocean sun fish
G. Changes in timing of developmentpaedomorphsis • 1. retention of larval characteristics into adulthood • 2. aquatic salamander • 3. by being able to remain in water may have escaped terrestrial predators • 4. aquatic environment is not as harshmay have escaped dessication • 5. genes that cause metamorphosis may have been blocked • 6. adult neotenic salamanders given injections may display adult traits
H. Neoteny –retention of juvenile traits into adulthood
H. Old genes being turned back on • 1. modern birds lack teeth • 2. aerodynamically not efficient • 3. ancestral birds had teeth • 4. genes for teeth still reside in bird chromosomes • 5. unlock the past-raw material for future evolutionary jumps?
Inbreeding
I. Jumping genes-transposons
J. Viral transmission
- Isolating mechanism
- Gene by gene test results
- Chapter 17 gene expression from gene to protein
- Unique introduction for portfolio
- Poolz tiers
- Neural circuits the organization of neuronal pools
- Neuronal pool
- Neural circuits the organization of neuronal pools
- Label the different types of neuronal pools in the figure.
- Alaska
- Neural circuits the organization of neuronal pools
- Convergence vs divergence neurons
- Dynamic disk pool
- Technology business management framework
- Figure 13-2 spinal nerves
- Casey company has five activity cost pools and two products
- Cost pools
- Pool lanes bpmn
- Industrialists of the late 1800s used pools and trusts to
- Industrialists of the late 1800s used pools and trusts to
- Was ist dynamic disk pools
- Buzz ghiz
- Gareth james pools
- Spring pools robert frost
- Mitc pool professionals
- Pools industrialization definition
- Trihalomethanes in swimming pools
- Processes of neuron
- Section 16-3 the process of speciation
- Example of biological species
- Taxonomic species concept
- Speciation, or the formation of new species, is
- Sympatric speciation example
- Factors affecting gene frequency slideshare
- Fox cladogram
- Connecting the concepts: macroevolution
- La spéciation
- Steps of speciation
- Allopatric speciation def
- Ecological speciation
- The origin of species chap 18
- Section 16–3 the process of speciation
- Types of speciation
- Ecureuil antilope grand canyon
- Speciation ecureuil antilope
- Example of parapatric speciation
- Population genetics and speciation worksheet answer key
- Speciation
- Prezygotic isolating mechanisms