Lecture 23 - Evo-Devo Flashcards
(30 cards)
Name Some Features that Developed in Animals Over Time:
- Gene expression
- Cell position
- Growth
Define Homology:
Similarity of the structure, physiology, or development of different species of organisms based upon their descent from a common evolutionary ancestor.
What are Some Limits to Natural Selection?
- Fitness trade-offs
- Limiting factors (food, water and shelter availability)
- Small population size or low recombination rate
- Constantly changing environments prevent perfect adaptations.
Where Does Variation Come From?
Changes in development.
How can Finely-Tuned Development be Changed without Disruption?
Modularity - development based on discrete and interacting modules (e.g. - dissociation; limbs and eyes grow independently)
How Many Body Plans of Animals are There?
~35.
Name Some Physical Constraints of Organisms:
Laws of diffusion, hydraulics and physical support (e.g. - no rotating wheels with blood supply nor no giant insects).
Name Some Pleiotropic Constraints of Organisms:
Pleiotropy: A gene plays different roles in different cells.
- Hox genes linked to stem cell proliferation
- Changing number of vertebrae increases risk of cancer
- Only exceptions are sloths and manatees.
Name Some Morphogenetic Constraints of Organisms:
- Organisms depart from normal development in limited number of ways (e.g. - cannot have short middle finger)
- Reaction-diffusion mechanism
- Morphogenetic construction rules (e.g. - logarithmic spiral)
How is Size Controlled in Repeated Structures?
- Via inhibitory cascade
- For example, teeth, fingers, vertebrae, body segments.
How is Shape Controlled During Growth?
- Via power cascade
- For example, teeth, horns, claws.
How are Molar Proportions Changed During Development?
Molars are initiated one at a time during development through the process of inhibition and activation to change their molar proportions.
How Many Fossil Hominins Exist?
15 species.
What is the Difference Between Function vs Development?
- Function explains change in size and proportions (e.g. - decreased bite force).
- Function cannot account for inhibitory cascade patterning at different sizes.
- Function leads to general result, but development explains how it was achieved.
How is the Serial Structure in Vertebrates Identified?
- Through the 1/3 rule.
- Followed by limb segments, vertebrae and fingers.
Explain the Development of Trilobites:
- Segments of pygidium and thorax follow inhibitory cascade in adults of trilobites.
- Segments follow inhibitory cascade during development as well.
- Pygidium segments are linear for 51 out of 53 species.
- Thorax segments are linear for 69 out of 99 species.
Explain the Ontogeny of Trilobites:
- Thoracic segments are linear early in development and remain linear
- Thoracic segments can change pattern later in development.
Do Modern Arthropods Have Similar Patterns to Their Ancestors?
Yes. Inhibitory cascade pattern occurs in early development however there is some deviation in adults.
How Does Tooth Growth Occur?
- Tooth develops from tip to base, and expands laterally.
- Can measure rate of lateral expansion as length increases.
Give Examples of Mammals:
Carnivores, deer, elephants, primates (including humans), whales, bats, pigs and marsupials.
Name All Vertebrates:
Bony fish, sharks, reptiles, birds, dinosaurs.
What is the Formula for Tooth Growth in a Power Cascade?
Tooth Growth:
log(Radius) = Slope * log(Distance) + Intercept
Power Function:
Radius = Intercept * Distance^Slope
What are Some Shape Variables of Teeth and Their Corresponding Aspect Ratios?
Slope : Pointiness:
- Slope = 1; Pointy
- Slope = 0.5; Blunt
Aspect Ratio : Length
- Aspect Ratio = 1; Short
- Aspect Ratio = 2; Long
How Would You Estimate an Elephants Age?
Through measuring their radius (or circumference) of their tusk.
- Longest tusk recorded: 3.5 metres.
