Lecture 16: Island Conservation & Extinctions

Transcription

1 WFB 074 Lecture 16: Island Conservation & Extinctions Readings this Week (Part 1) Powledge, F Island biogeography s lasting impact. BioScience 53: Wilcove, D. S The Condor s Shadow: the Loss and Recovery of Wildlife in America. pp , Chapter 7: Too gentle for this world. New York: W. H. Freeman & Co. Finlayson, C., and T. Finlayson. Undated Brochure. Invasive plant threatens Midway Atoll seabirds. US Fish and Wildlife Service, Midway Atoll National Wildlife Refuge.

2 WFB 074 Announcements Midterm results Count (N) 72 Minimum Value 28 Maximum Value 53 Average Median 42.5 Standard Deviation pts pts pts pts pts >50 pts 0

3 WFB 074 Lecture 16: Island Conservation & Extinctions Types of Islands Continental or Landbridge Islands Part of continental shelf. Once -or periodically, through earth history - connected to mainland. Sri Lanka, Sumatra Map from:

4 WFB 074 Lecture 16: Island Conservation & Extinctions Types of Islands Oceanic Islands Arise from beneath the ocean surface, volcanic San Benedicto Island of the west coast of Mexico: 1952 eruption doubled size of island. Photo: Luke Wooller, Picasa

5 WFB 074 Lecture 16: Island Conservation & Extinctions How do plants and animals get to islands? Chance Dispersal Fruits of Boerhaavia diffusa reveal sticky yellowish ribs, in addition to sticky hairs. Ideal for catching onto feathers Juvenile sooty tern with fruits of the Boerhaavia diffusa attached near its eye. Heimerliodendron brunonianum has fruits with ridges that are amazingly sticky. Unlike rubber cement, this substance takes years to dry. Map: Carlquist 1981 Photos:

6 WFB 074 Lecture 16: Island Conservation & Extinctions How do plants and animals get to islands? Island Rafting from: Carlquist Island Life

7 WFB 074 Lecture 16: Island Conservation & Extinctions Characteristics of Islands The number of species increases with Island Area Relationship between Number of Species (S) and Island Area (A) for the reptiles and amphibians of the West Indies (Data from Darlington 1957). Note: Axes are logarithmic. This can be expressed with equation: S = c A z Where c and z are fitted values (constants). = Species-Area Relationship

8 WFB 074 Lecture 16: Island Conservation & Extinctions Characteristics of Islands On islands, the number of species decreases with isolation Effect of distance from mainland bird species in the Lesser Antilles (David Lack)

9 WFB 074 Lecture 16: Island Conservation & Extinctions Characteristics of Islands Island Colonization At first (left side of the graph) the colonization rate will be high because there are lots of open ecological niches on the island that can be easily filled. Rapid dispersers on the mainland (source area) will find the island quickly. The two curves represent Near Islands and Far Islands relative to the source area. The near island curve indicates a higher rate of species colonization because it will simply be easier for animals to migrate out to a near island. The far island rate is lower because the farther from the source area an island is, the more difficult it will be for species to reach it. empty island full island

10 WFB 074 Lecture 16: Island Conservation & Extinctions Characteristics of Islands Extinction Curves A large island will hold more species, it will have relatively low rates of extinction compared to a small island. A small island will theoretically suffer higher rates of extinction due to lesser area and resources for species.

11 WFB 074 Lecture 16: Island Conservation & Extinctions Characteristics of Islands Combining Colonization Rate and Extinction Rate Predicted equilibrium points for four separate case: S FS = Species # for a far, small island; S NS = species number for a near, small island S FL = Species number for a far, large island S NL = Species number for a near, large island. The number of species increases with area and decreases with isolation of an island = Mac Arthur and Wilson s Equilibrium Model of Island Biogeography (1963).

12 WFB 074 Lecture 16: Island Conservation & Extinctions Characteristics of Islands E.O. Wilson Robert H. MacArthur The number of species increases with area and decreases with isolation of an island = Mac Arthur and Wilson s Equilibrium Model of Island Biogeography (1963).

13 WFB Island Ecosystems & Extinctions Unique Island Faunas Unusual Island Adaptations Galapagos Marine Iguanas Amblyrhynchus cristatus Live in crevices and burrows along lava coast. Only lizard at home in the surf. Feeds off brown slimy fonds of Sargassum, a brown alga. Unafraid of humans.

14 WFB Island Ecosystems & Extinctions Unique Island Faunas Unusual Island Adaptations Gigantism Galapagos tortoises Chelonoidis (Geochelone) nigra Distinctive races throughout the islands. Chelonoidis nigra ssp. abingdoni IUCN Red List: EW (Extinct in Wild)

15 WFB Island Ecosystems & Extinctions Unique Island Faunas Gigantism & Flightlessness in Birds Unusual Island Adaptations Elephant Bird (Aepyornis) of Madagascar extinct ~ 1650 Mauritius Dodo (Raphus cucullatus) Related to Pigeons and Doves (Columbidae). Short description by Dutch admiral Cornelis Matelief de Jonge in Extinct about 1665.

16 WFB Island Ecosystems & Extinctions Unique Island Faunas Gigantism & Flightlessness in Birds Unusual Island Adaptations Kakapo (Strigops habroptila) Flightless nocturnal parrot endemic to New Zealand. World s heaviest parrot. One of the last kakapos on Maud Island in New Zealand's Marlborough Sounds is fed by conservation officer Daryl Eason in (

17 WFB Island Ecosystems & Extinctions Unique Island Faunas Galapagos Finches Galapagos The remaining landbirds form a most singular group of finches All are peculiar to this archipelago Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends. (Charles Darwin, Voyage of the Beagle)

18 WFB 074 Lec Island Conservation Hawaiian Archipelago

19 WFB Island Ecosystems & Extinctions Unique Island Faunas Hawaii

20 WFB Island Ecosystems & Extinctions Unique Island Faunas Hawaii Hawaiian Honeycreepers (Drepanididae) Originally about 33 species. At least 10 sp. extinct. Most remaining species are endangered.

21 WFB Island Ecosystems & Extinctions Unique Island Faunas Hawaii Adaptive Radiation of Hawaiian Honeycreepers (Drepanididae) From Brown & Lomolino 1998

22 WFB Island Ecosystems & Extinctions Unique Island Faunas Hawaii Honeycreepers Example: Palila (Loxioides bailleui) on mamane tree Finch-like bill. Specialized ecological niche on upper slopes of Mauna Kea. Dry open mamane woodlands. Described as numerous in Habitat loss from introduced livestock. Less than 10% off former range remains.

23 WFB Island Ecosystems & Extinctions Unique Island Faunas Hawaii Honeycreepers Example: Akiapolaau (Hemignathus munroi) Curved beak. Upper beak longer than lower beak. Bark Pickers. Insectivorous.

24 WFB Island Ecosystems & Extinctions Unique Island Faunas Hawaii Honeycreepers Example: Akohekoe Crested Honeycreeper (Palmeria dolei) Survives only in narrow belt of rainforest on the upper slopes of Haleakala volcano on Maui. First known nest discovered only recently.

25 WFB Island Ecosystems & Extinctions Introduced Species GOAT MONGOOSE PIG

26 WFB Island Ecosystems & Extinctions Introduced Species New Zealand s Stephen Island Stephen Island Wren (Xenicus lyalli) Ornithologist W. R. B. Oliver: The history of this species, so far as human contact is concerned, begins and ends with the exploits of a domestic cat. In 1894 the lighthouse keeper s cat brought in 11 specimens, which came into the hands of H. H. Travers A few more captures made and duly reported by the cat and then no more birds were brought in. It is evident, therefore, that the cat which discovered the species also immediately exterminated it. (from S. Carlquist Island Life)

27 WFB Island Ecosystems & Extinctions Introduced Species Managing Feral Pigs on Hawaii Nonnative feral pigs degrade native wet forests in Hawaii via rooting and mixing of soil horizons, trampling and consumption of native plants, and transport of nonnative seeds (Photo: Hawaii Volcanoes National Park). See Dr. Creighton Litton website: Dept. of Nat. Resources & Env. Management (Univ. of Hawaii, Manoa): More on this at Cornell Lab of Ornithology: conservation /success/hawaiian_honeycreepers

28 WFB Island Ecosystems & Extinctions Introduced Species In-class VIDEO: Scene 10 Under Threat from a Plant from Nat. Geogr. Hidden Hawaii Managing Golden Crownbeard (Verbesina encelioides) on the Hawaiian Islands