Lec: 9: Dispersal and Biogeography Lecture Notes

Practice questions covering the concepts of dispersal, migration, jump dispersal, diffusion, biogeographical realms, and distribution patterns from the lecture transcript.

How is dispersal defined in the context of biogeography?

Dispersal is when organisms move away from their place of birth and expand their species range to places where they were not previously living.

What is the difference between migration and dispersal?

Migration involves moving from a place and later returning to that same place,

Dispersal involves permanent range expansion.

Nomadism

A herd does not have a set territory and is constantly moving from one place to another in search of resources

Vagrant

An individual animal found in an area outside its normal range that has not established a viable population or colony there.

What three requirements must be met for a movement to be considered a biogeographic dispersal?

1. Individuals must leave their old area

2. Survive the journey (including any barriers)

3. Establish a viable population in the new area.

What are jump dispersal and diffusion?

Jump dispersal is a rare, long-distance movement over a barrier to a new habitat, while diffusion is a slow advancement of a species' range edge into neighboring habitats.

What event in Indonesia in $1880$ provided a case study for quick colonization of a sterilized habitat?

The massive volcanic explosion of the island of Krakatoa Balua.

Aerial plankton (or aeroplankton)

Small organisms or life stages—such as spores, pollen grains, microscopic animals, and ballooning spiders—that are carried through the air.

What bird serves as a documented example of a non-human caused jump dispersal from Africa to the Americas around $1937$?

The Cattle Egret.

Vagility

refers to how good an organism is at dispersing

What is the difference between a diaspore and a propagule — passive dispersal?

A diaspore is a specific life history stage adapted for dispersal (e.g., a ballooning spider)

A propagule is any dispersal agent or life stage that is the primary one for dispersal.

phoresy (or hitchhiking)

A mode of dispersal where an organism uses another organism for transport without harming it, such as pseudoscorpions grabbing onto the legs of flying insects.

Distinguish between endozoochory and exozoochory.

Endozoochory involves seeds being dispersed inside an animal (e.g., eaten fruit), while exozoochory involves seeds attaching to the outside of an animal (e.g., cockleburs).

How did the Isthmus of Panama act as both a barrier and a corridor?

It was a complete physical block to the dispersal of marine species but served as a corridor for land organisms moving between North and South America.

Filter

A zone that allows some species to pass through while blocking others due to environmental conditions or competition, such as Wallacia between Indonesia and Australia.

Describe a sweepstakes dispersal event.

A random chance event allowing dispersal that would normally be impossible

Ex.) green iguanas rafting from the island of Guadalupe to Anguilla during a hurricane

Cosmopolitan species

A species with a very wide global distribution

Ex.) Peregrine falcon or the Sperm whale

Endemic species

A species native to and restricted to a specific area

Ex.) Devil's Hole pupfish or the Kahazi spray toad.

What are the major terrestrial biogeographical realms named by Wallace?

Nearctic

Palearctic

Neotropical

Afrotropical

Indomalae (Oriental)

Australian/Oceanic/Antarctic

What characterizes a disjunct distribution?

When a species or taxonomic group is found in separate areas with wide gaps in between where they do not occur.

What is a relict distribution?

A distribution where a species persists in isolated 'leftover' areas after its once-broad range has disappeared, such as the lily populations left on mountain slopes after glacial retreat.

What is evolutionary convergence?

When unrelated species evolve similar physical traits or behaviors due to living in similar environments, such as Old World and New World vultures.