Biogeography Ch 1-7

Content for 1st test

What is biogeography?

A science that seeks to understand spacial patterns of biological diversity

What is an “allied science?”

A combination of multiple scientific disciplines

Describe the concept of immutable earth

The idea that the earth, and everything on it, is unchangeable

What was Carolus Linnaeus’ hypothesis of species dispersion?

• All lifeforms were placed along the slope of a mountain near the equator

• Species dispersed as the mountain grew broader

What was Buffon’s hypothesis of species dispersion?

That all life originated in a region of Europe in a time when the earth’s climate was more homogenous, and migrated southwards as temperatures cooled

What is Buffon’s law?

Environmentally similar, but geographically isolated regions, have distinct assemblages of mammals and birds

What characterized the Age of Enlightenment in the late 18th century?

The globalization of biogeography and the sharing of knowledge

What did Alexander Von Humboldt study?

Climatic associations of plant communities, expanded upon the theory of floristic zonation to be applied along elevational gradients

Who was it that proposed that the earth was mutable?

Charles Lyell

What are the three major advancements in biogeography of the 19th century

• A better estimate of earth’s age

• A better understanding of ocean and continent dynamics 

• Better understanding of the mechanisms by which species disperse and become different species 

Define uniformitarianism

The idea that the processes working on the Earth today have always existed

What is considered the father of zoogeography?

Alfred Wallace

What is the Linnean shortfall?

It is hard to group and classify species when we don't know all the species that exist

What is the Wallacean shortfall?

If you see a species, you can say it was there. But if you don't see it, you cannot guarantee it wasn't actually there— leads to biases in species observation

What are the two types of inferences in science?

Induction and deduction

What is inductive reasoning?

Inferring a larger conclusion based on information from particular instances

Ex. The sun has risen every morning, and there will be morning tomorrow → the sun will rise tomorrow 

Why is inductive reasoning sometimes flawed?

Because it may lead to false conclusions (Ex. The more firefighters at a burning house, the bigger the damage bill → firefighters cause damage)

What is deductive reasoning?

The conclusions follow necessarily from their premises, if the premises is true then so must be the conclusion

(f the hypothesis is true, your predictions should occur)

Ex. If all bats can fly, and Myotis lucifugus is a species of bat → Myotis lucifugus are able to fly 

Why is deductive reasoning sometimes flawed?

• Can lead to confirmation bias, as one instance does not confirm a theory

• Your hypothesis needs to be true for your predictions to be correct

What is the fundamental unit of biogeography?

Ranges

Define: Niche

The range in which a species can persist, and fulfill its role

What are the two components of the Hutchensonian Niche

The fundamental and realized niche

What is the fundamental niche?

• A set of abiotic conditions in which a species can persist in the absence of interactions with other species

• The “ideal scenario” for a species

• Only considers abiotic components 

What does the width of a species’ niche say about their tolerance?

• A wider niche implies a more tolerant species that can inhabit a larger area

• A narrow niche is the opposite, implying a narrow range of suitable conditions

What is the realized niche?

• The set of conditions in which a species can persist given interactions with other species

• More realistic model of what really happens in nature 

• Takes into account competition & other biotic components

Why might a species not fill their niche?

• Encroachment of predation or invasive species

• Habitat fragmentation

• Newly introduced species that hasn’t had time to expand

What is dispersal?

An active or passive attempt to move from a natal/breeding site, to another breeding site

How is dispersal different from migration?

Animals will return after migrating, while dispersal is a permanent relocation

What is the difference between natal and breeding dispersal/

• Natal dispersal: A young individual moves away from where they were born 

• Breeding dispersal: Adults moving to a new breeding site

What are the three types of passive dispersal?

• Hydrochory: Dispersal through water 

• Anemochory: Dispersal by wind

• Zoochory: Dispersal by animals

What is ballochory?

A form of active dispersal used by plants that are able to shoot their seeds

What is a species?

A group of related organisms that share common characteristics, and are capable of interbreeding 

What are the two types of cohesion that individuals within a species share?

• Spatial cohesion: Individuals will stay close together

• Temporal cohesion: Maintains consistent interaction patterns over time (Ex. coordinated movements, resource sharing, hierarchies)

What is speciation?

The process by which two or more species evolve from an ancestral population

What is a reticulate species?

A hybrid species with its own evolutionary history and trajectory, niche, and geographic structure

What type of species is indicated in red here?

A reticulate species

What are the four processes that drive microevolution

• Mutation

• Genetic drift

• Natural selection

• Gene flow

Define: Mutation

A permanent change in a DNA sequence

What are the four types of mutation?

• Substitution of a single nucleotide

• Deletion of a single/multiple nucleotides 

• Insertion of a single/multiple nucleotides

• Inversion of a single/multiple nucleotides

What is genetic drift?

Occurrence of random changes in allele frequencies between generations

Why is genetic drift less effective in larger populations?

Because changes tend to even themselves out over time

What is gene flow?

Movement of alleles within/between populations due to dispersal of offspring

Why does gene flow counter genetic drift & natural selection?

Because it has a homogenizing influence

What are the three main modes of speciation?

• Allopatric

• Sympatric

• Parapatric

What is allopatric speciation?

Speciation that occurs due to a physical barrier isolating a population

What is parapatric speciation?

Speciation that occurs in adjacent populations across a larger area

What is sympatric speciation?

Speciation that occurs within the same area between overlapping species

What is disruptive selection?

Selective pressures that cause a population to adapt to different niches (ex. Evolving towards the extremes)

What are the two types of species distribution modelling

Correlative (empirical) and mechanistic (biophysical)

What does correlative modelling compare?

Involve predicting a species’ potential distribution using statistical analysis of correlations between where a species randomly occurs, and the known environmental conditions at said locations

What does mechanistic modelling compare?

Involves predictions for species location by understanding their needs 

What type of modelling is MaxEnt?

Presence only, correlative/empirical modelling

What does SDM stand for?

Species distribution modelling