Island Biogeography

Question 1

Island biogeography

Answer 1

the study of the ecological relationships & distribution of organisms on islands, & of these organisms’ community structures

Question 2

How does the size of the island influence species richness? Why?

Answer 2

Species richness increases as the size of the habitat increases

• Dispersing species are more likely to find larger habitats than smaller habitats, particularly when those habitats are islands
• Any given latitude, larger habitats can support more species than smaller habitats. Larger habitats are capable of supporting larger populations of any given species, & larger populations are less prone to Extinction.
• Larger habitats often contain a wider range of environmental conditions, which in turn provide more niches that support a larger number of species, and a wider range of environmental conditions also provides greater opportunity for speciation over time.

Question 3

How does the distance an island is from the mainland affect species richness? Why?

Answer 3

• Oceanic islands that have more distance from continents generally have fewer species than islands that are closer to countenance, distance matters because many species can disperse short distances, only a few can disburse long distances
• If two islands are the same size & contain the same resources the nearer island should accumulate more species than the farther Island because it has a higher rate of immigration by new species.

Question 4

What is the threat that invasive species pose to island ecosystems?

Answer 4

• Many island species have evolved to be specialists instead of generalists because of the limited resources, such as food & territory, on most islands
• The long-term survival of specialists may be jeopardized if & when invasive species, typically generalists, are introduced & outcompete the specialists

Question 5

Biosphere reserve

Answer 5

• a protected area consisting of zones that vary in the amount of permissible human impact

Question 6

What are habitat islands and what is their importance?

Answer 6

• habitat islands are often surrounded by less hospitable habitats (ex: a national park with agricultural fields surrounding)
• habitat islands can be set aside as a natural habitat for a given species or entire ecosystems for conservation periods

Question 7

Why do conservationists have to consider the distance between metapopulations (spatially distant populations that are connected by occasional movements of individuals between them)?

Answer 7

• it is less likely that species can travel among protected areas that are far apart; when a species has been lost from one ecosystem, it will be harder for individuals of that species from other ecosystems to recolonize it
• A species is more likely to be protected from extinction if it can be rescued by dispersers from a neighboring population

Question 8

Edge Habitat

Answer 8

• habitat occurs where two different communities come together, typically forming an abrupt transition, such as where a grassy field meets a forest