Lecture 1 –
Intro to Class: Why Study Islands?

Islands: Ecology, Evolution, & Conservation

Dr. James A. Danoff-Burg

Department of Ecology, Evolution, & Environmental Biology

Columbia University

Why Study Islands?

• Natural Laboratories

– Genesis of many ecological theories

• Many centrally important in conservation biology

• E.g., adaptive radiation, taxon cycle, community assembly theory, island biogeography, metapopulations,SLOSS, etc.

– Basic ecological & evolutionary processes are revealed

• Evolution is most forceful on islands

• Ecology is often simplified on islands

Why Study Islands?

• Processes / theories are relevant to geographical analogues

– Mountain ecosystems

– Ocean reefs

– Lakes / Ponds

– Discrete natural fragments

– Habitat fragments

– Many others…

Why Study Islands?

• Interesting trends in species diversity

– Disproportionately large number of endemic species

• Disproportionately contribute to global biodiversity

– Species-poor

• Difficult to get reach

– Disharmonic

• Have dominance of a few taxa

• Total absence of many common taxa

• Absence of terminal predators

Why Study Islands?

• Ecologically threatened

– Include some of the most imperiled ecosystems

– Globally, the majority of species losses have been of endemic island species

• Approx 366 of 488 of well-known animal taxa extinctions on islands

• 75% of mollusk, bird, mammal extinctions since 1600

• Source: Groombridge 1992 (as in Whittaker 1998)

Why Study Islands?

• Recent Historical Extinctions (3)

– First when colonized by aboriginals

• Exotics and clearing

• In general, low population sizes

– Second when contacted by Europeans

• Exotics and clearing, but by more people

– Currently even more greatly threatened

• Acute overpopulation / overexploitation

• Habitat fragmentation / clearing / degradation

• Invasive species, oil spills, etc.

Why Study Islands?

• Centerpieces of conservation biology

– In their own right

• Need to conserve these hotspots of biodiversity

– Ecological analogues

• Processes on islands are relevant to imperiled patchy terrestrial, aquatic, & marine habitats

– Planning for future

• Large habitats will become fragmented

• Fragmented patches will be conserved similar to islands

Why Study Islands?

• Beautiful location

– Beachfront field sites are common

• Water Sports

– Sailing

– Surfing

– Snorkeling

– Diving

• Improve quality of tan

• Tropical fruit drinks

Structure of Class

• Weekly meetings

– Wed, 4:10 – 6:00, 1015 Schermerhorn Hall Extension

• Responsibilities

– Readings from text

– Readings from primary literature

– Writing assignments

– Participation

• Required text

– Whittaker, R. J. 1998. Island Biogeography. Oxford University Press. ISBN: 0-19-850020-3

Grading

• Grading will be based on:

– 7 Biweekly Papers: 40%

• Short 1-2 page summaries & interpretations of theories

– Participation in class: 30%

– Term paper: 30%

• Integrates & interprets the ideas discussed during this semester

• Conservation issues of an island ecosystem of your choice

• Literature review

• 15 double-spaced pages

Syllabus

• Week 1 – Islands as natural laboratories (ch 1 & 2)

• Week 2 – Types of ecosystems present on islands (ch 1 & 2)

• Week 3 – Islands as biodiversity hotspots (ch 3)

• Week 4 – Speciation (ch 4 & readings)

• Week 5 – Historical biogeography and islands (ch 4 & readings)

• Week 6 – Arrival of new species and population-level change (ch 5)

• Week 7 – The taxon cycle (ch 6 & readings)

• Week 8 – Adaptive radiation (ch 6 & readings)

• Week 9 – Equilibrium theory of island biogeography (ch 7)

• Week 10 – Community assembly, structure, and function (ch 8)

• Week 11 – Metapopulation dynamics (ch 9 & readings)

• Week 12 – Island conservation issues: Fragmentation (ch 9)

• Week 13 – Island conservation issues: Invasive species (ch 10 & readings)

Defining an Island

• What is an island?

• Key properties

– Discrete patches of habitat

• Typically small

• Have limited number of populations within each species

– Isolated from other patches

– Surrounded by an inhospitable matrix

• Sea water, cleared forest, desert, arable land, etc.

– Minimum size?

• Land that is too small to sustain a freshwater supply: beaches or sand bars

– Need more than about 10 ha for constant freshwater supply

Examples of Islands

• 4 general categories

– Oceanic Islands

– Continental Shelf Islands

– Habitat Islands

– Non-Marine Islands

Oceanic Islands

• Properties

– Located over oceanic plate

– Have never been connected to mainland

– Formed due to volcanic or plate subduction activities

• Examples

– Comprise approx 3% of Earth’s land area

– Archipelagos

– Seamounts

• Undersea mountain, forming or subsiding

– Guyots

• a former island cut off below sea level by erosion

– Reefs(?) – fringing, barrier, and atoll

Continental Shelf Islands

• Properties

– Located on continental shelf

– May have been connected with mainland in past

– Separated due to seafloor spreading

– May have been formed due to deposition or siltation

• Examples

– Keys

– Barrier islands

– Madagascar, New Zealand

Habitat islands

• Properties

– Terrestrial habitats

– Surrounded by very different habitats from that of the habitat island

– Not surrounded by water

– Assemblage of unrelated island types

• Examples

– Discrete natural fragments

– Human-caused habitat fragments

– Lakes & ponds

– Mountain ecosystems

Non-marine islands

• Properties

– Islands surrounded by freshwater

– Intermediate in characteristics between continental shelf & non-marine islands

– Close to surrounding source populations

• Examples

– Crater Lake island

– Islands in the stream

• River islands (Amazon, Mississippi)

Assignments for Next Week

• Next week: Island Environments

– Geography, climate, abiotic factors, disturbances

• Read

– Chapters 1 & 2 in Island Biogeography, Robert Whittaker

– Whittaker 95. Disturbed island Ecology. TREE. 10:421-425.

• Write

– 1 page single spaced essay on when fringing reef ecosystems should and should not be considered island analogues

– Take into consideration the methods of formation

– Use island properties: above and discussed in Ch 1&2 of Whittaker

– Due next week at start of class