Fundamental Unit of Biogeography

Geographic Range

Conveying Range – Outline Maps

Range of Sooty Butterfly (Zegris eupheme)

Conveying Range – Outline Maps

Range of Racoon (Procyon lotor)

Conveying Range – Outline Maps

Range of Three-ridge Mussel (Amblema plicata)

Conveying Range – Outline Maps

Bird Map

Conveying Range – Dot Maps

Locations for emerald shiner (Notropis atherinoides)

Conveying Range – Dot Maps

Locations for brown trout (Salmo trutta) – dot and outline map

Conveying Range – Dot Maps

Blue jay distribution in 20th precentile contours

Conveying Range – Contour Maps

Blue jay distribution as relative abundance

Limitations

• Outline – not across entire range (clumped disperson)

• Dots – inaccuracies of locale information• Contour – spotty data• BUT

– Georeferencing– Geostatistics– GIS – integration of data

Patchy Nature of Range - Spatially

Patchy Nature of Range - Temporal

Factors Affecting Distribution of Species

• Limiting abiotic factors (range of tolerance)• Biotic interactions• Hutchisonian niche – n-dimensional

hypervolume

Niche Dimensions and Range

• Fundamental niche• Realized niche• Fundamental geographic range• Realized geographic range

Distribution of the barnacle Chthamalus stellatus (Connel 1961)

Gaps in Distribution

• Metapopulations– Sink and source subpopulations– Atlantic snail

• Barriers

Other Source and Sink Distributions

• Migration – temporal and resource-driven

• Irruptions

Red locust (Nomadacris septemfasciata) – source (black) and sink (gray) range

Of Note

• Any fluctuations of population size will influence the realized geographic range

All winter at high latitude – will extend range with resource shortage

Variation over Range

Abiotic Limiting Factors

• Range of tolerance• Fundamental niche• Overlapping effects• Trade-offs for tolerance of given factor

Disturbance

• Limit/expand range of species• Patch dynamics• Intermediate disturbance hypothesis• Bluff and Great Lakes Examples

Pupfishes (Cyprinodon nevadensis)

• Adults tolerate 0 – 42°C

• Found in cold to hot springs across range

• Eggs develop at 20-36°C

• Need access to a sink habitat to persist

Biotic Factors - Competition

• Exploitative• Interference• Ranges are often reflection of “ghosts of

competition” past – example Connell’s barnacle study

Kangaroo Rats (Didymops spp.) – was it competition?

• Same niche• Two disjunct species• Realized niche of 3

species segregated by substrate

• Competitive exclusion?• Resource partitioning?• Parapatric speciation?• No evidence of

competition on edges

Biotic Effects - Predation

• Community regulator• Coevolutionary mechanism

Loss of Barriers

Keystone Predator

Implications outside range of otter?

Mutualism – Correlate to Distribution?

Diffuse Competition

• MacArthur (1972) – southern limits of many N. Amer. Birds not attributable to– Abiotic factors– Habitat limitation– Competition or Predation

• 202 land birds in Texas, only 29 found in Panama; Panama 564 land bird species

Yellow warbler (Dendroica petechia) – one of the 29 found in both.Insectivore, limited to mangrove swamps and islands in tropics