BIOL 2251 Study Guide - Midterm Guide: Ecological Speciation, Alfred Wegener, Species Problem
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BIOL 2251
Opportunity 3 Review
Chapter 6 – Dispersal and Immigration
• ALFRED LOTHAR WEGENER (1880-1930)
o Plate tectonics
o Continental Drift
▪ Explained why the same/similar species could be found in two separate,
sometimes far away, locations
▪ There is Paleontological Evidence
▪ The continents could possibly come together again
• DONALD RUMSFELD
o Basiall stated that there is a lot that e do’t ko
• 30% of all animals are beetles
• Insects take up about half of the species chart
• We only allocate money and scientific effort into three groupings of eukaryotes, out of
many
• Corixidae
o Taxonomy:
▪ Insecta
▪ Hemiptera
▪ Genus: Corixidae
▪ Species: punctata and affinis
o Hutchinson noticed two types in the pond:
▪ C. punctata
• Larger
▪ C. affinis
o They coexist because they have different breeding seasons
▪ Larger species breeds before the smaller species
• Why do we have so many different types of species? (HUTCHINSON, 1959: Homage to
Santa Rosalia)
o 1. Natural Selection
o 2. Isolation post-dispersal or vicariance
o 3. Speciation events:
▪ Allopatric
▪ Sympatric
▪ Competitive
o 4. Gause’s La AKA Copetitie Elusio Priiple
o 5. Lotka-Volterra Equations – predator-prey relationships
▪ e.g. increased predation = decreased prey
o 6. Food chain – energy transfer
▪ Increased smaller animals
▪ Depending on plants
▪ Increased primary consumers (most animals)
o 7. Character Displacement
▪ The divergence of a feature of two similar species where their ranges
overlap so that each uses different resources.
▪ When two species live in separate habitats they can have very similar
morphology; when they live in the same habitat their characteristics
diverge
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BIOL 2251
Opportunity 3 Review
▪ Example: Finch Beak Depth – beak depth changes when they inhabit the
same island but are similar on separate islands
o 8. Mosaic nature of the environment
▪ Increased niche space
o 9. Stable Environment
▪ Stable and more complex food webs
• True or false: A complex trophic food web is more stable than a simple one.
o True
• Three fundamental processes
o Extinction
o Dispersal
o Evolution
• Dispersal
o Movement away from point of origin/birthplace
o Usually confined to one life-history stage
o Natural selection favors movement that is a modest distance away from the
birthplace. Why?
▪ Modest movement away from origin:
• 1. Intraspecific competition
• 2. Sexual Reproduction – not out of range
• 3. Energy Conservation
• 4. Gene flow to nearby populations
▪ Modest eause the eiroetal paraeters hage too uh
otherwise, due to spatial autocorrelation
o 3 key events that lead to a successful dispersal:
▪ Travel to a new area; requires morphological adaptations to make the
trip.
▪ Withstand unfavorable conditions to make the trip.
▪ Establish a viable population upon arrival.
o Jump Dispersal
▪ Long distance dispersal that happens in a short time.
▪ Example: Krakatau
• Erupted in 1883, but by 1933 there were 271 plants species, 31
bird species, invertebrates.
• This as ahieed steppig stoe dispersal aross the islad
chain and jump dispersal from source lands of Java and Sumatra.
▪ Ho a ou erif the speies juped?
• Phylogeny (DNA)
▪ Accounts for similar species inhabiting similar habitats in different
geographic areas.
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BIOL 2251
Opportunity 3 Review
o Dispersal V Diffusion
Jump Dispersal
Diffusion
-long distance
-few individuals
-whole populations
-similar species inhabiting similar
habitats in entirely different
geographic locations
-Gradually spreads distribution out
from argis of speies’ preious
range
-fast, one or couple rare events
-slow, over the course of
generations; multiple attempts
o 3 steps of Diffusion
▪ 1. Initial invasion
• maybe requiring repeated events and subsequent adaptations
▪ 2. Once established, diffuses at exponential rates
▪ 3. Eventually slows when the species encounters physical, climatic, or
ecological barriers.
o Example of Diffusion:
▪ Bubulcus ibis (cattle egret) is native to Africa. In the 1800s it diffused into
South America, and then into North America;
▪ Austrailian Cane Toad: Introduced by humans; diffused then jumped
o Insects that can disperse at higher altitudes usually have small wings
o Active Dispersal:
▪ Dispersal of an organism using its own power
▪ Vagility
▪ Can disperse a moderate/farther distance
o Passive Dispersal
▪ Dispersal by being carried by another agent, like wind or water, or other
organisms
▪ life stage that is dorat ad a surie eiroetal etrees ad
a go ak ito its life le after dora ad dispersal.
▪ Pagility
▪ Can disperse only a small distance, closer to their origin
o Phoresy: Animals transported by other animals
▪ Ex: mussel larvae in fish host
o Exozoochory: Plants attach themselves to the outside of animals
o Endozoochory: Plant propagules (seeds) that travel inside an animal
o The Aidetal – Grinnell (1922)
▪ Instead of traveling their normal route to Mexico, some Monarch
butterflies ended up in Cuba. To this day, some still travel to Cuba. No
idea what caused this to happen – maybe a storm – but it was accidental
they ended up in Cuba.
o Corridors: Very similar habitats than either side; allows for dispersal
o Filter: Different habitat between two or more areas; restricts dispersal
▪ E: Wallae’s Lie that auses a sharp faual gap ear Bali
o Sweepstakes: rare event
▪ Ex: 15 iguana individuals got aught up i hurriae, a fe o the
lotter ad laded o a egetatio raft to a e islad ad ere ale to
thrive
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