Island Biogeography Part II

Species De-Extinction (or resurrection biology)

Reverses plant/animal extinctions by creating new versions of previously lost species

• Back breeding

• Cloning

• Genome editing

Species De-Extinction goal

Re-establish dynamic processes that produce heathy ecosystems and restore biodiversity

Habitat conservation

1) Habitat Degradation

2) Habitat Fragmentation

3) Habitat conversion

4) Habitat isolation

Habitat Fragmentation (meaning) 

It takes place when area of habitat is divided into smaller patches that are disconnected from each other (Wilcove et. al. 1986) 

Habitat Fragmentation (3 main results) 

1) Reduction of total habitat (habitat loss) 

2) Fragmentation or isolation of habitats (Loss of connectivity) 

3) Alteration of overall landscape 

SLOSS Debate (What is it) (Jaren Diamond -1975) 

One of the first applications of the IBT to conversation issues. 

*Can be used to determine the size of the protected area) 

Single large or several small

Single large

• Island Biogeography Theory (1963 or 1967) 

Several small 

• Metapopulation theory (1969) 

Habitat patches if behave like islands

Predicts that species richness should decrease with fragment size.

Levin’s (1969)

Introduced the idea of metapopulations to explain how patchiness work

Metapopulation (made of) 

Made up of smaller subpopulations that live in separate habitat patches 

Patches are found within a larger landscape that has unsuitable areas for living.

• Shaded areas provide an excess of individuals who emigrate to and colonize sink habitats. 

Sinks and Sources in metapopulations

Persistence of some local populations (sinks) depends on some migration from nearby populations (sources). 

Protecting metapopulations (fragmented habitat)

You need to protect several habitat patches, not just the largest one.

Island biogeography theory

• Large reserves facilitate re-colonization from other areas and support greater diversity and interaction.

• Populations reach higher abundances in large reserves

Large areas may include

• Low-quality habitat

• High-quality habitat

Ensure balance between diversity/quality of resources available for various species

Contains birds that will not fly over water

• Spotted antibird (hylophalx naviodes) 

• Bicoloured antibird (Gymnopithys bicolor) 

• Ocellated antibird 

Barro Colorado island Reserve

• These 3 bird species were tracked for 11 years (1960-1971). Only 1 species show stable population 

• Since BCI was made a reserve, 45 (22%) of avifauna were extinct by 1960 b/c the island was small, leading to greater levels of competition, and in turn, higher levels of extinction (Competitive exclusion) 

Metapopulations Theory: Several small reserves

The benefit of having several small reserves (or protected areas) is that they can encompass a variety of habitat types and support more populations, provided there is good connectivity for dispersal

Chicago Wilderness

The Chicago Wilderness Project includes about 240 small protected areas (different owners/sources) but together form a fantastic conservation network of protected areas. 

Buffer zones can include

• Reduce edge effects 

• Prevent human-wildlife conflicts 

• Support Biodiversity 

• Enhance ecosystem services 

Reduce Edge Effects

Minimize impact of habitat edges where human activity can penetrate and affect the protected area. the

Prevent Human wildlife conflicts

Serve as transition areas to conflicts, especially in regions used for hunting/harvesting. 

Support Biodiversity

Provide extra habitat for species, ensuring their populations can thrive even near human-dominated landscapes 

Enhance ecosystem services

Maintain ecosystem functions like water filtration, climate regulation, and soil conservation, etc. 

Corridors 

Linear strips of vegetation that provide connectivity. 

• Riparian areas, shelter bilts, fencerows, hedgerows, etc. 

• May be patchy or fragmented. They might still assist in movement of organisms. 

Importance of corridors

A protected area is essential for countering fragmentation and ensuring population connectivity.

*Loss of habitat connectivity is one of major consequences of habitat fragmentation. 

• The importance of corridors for wildlife to move (or disperse) within habitats, including protected areas, is critical.