Biogeography of Hawaii Volcano tops from Ocean Floor

Biogeography of Hawaii

• Volcano tops from Ocean Floor

• Remote

• Colonization Rare

• Adaptive Radiation of Founder Species

Origin of Island Archipelago

• Hot spot moves or plates move over hot spot

• Volcanoes build to surface then erode or subside

• Current islands arose after previous islands were already submerged

• Exceedingly limited island hopping

Island Development

• Island Appears

• Colonized by Plants

• Biota Establishes

• Biota Stabilizes

• Island Moves Away from Hot Spot

• Waif Founders Lack Competition

• Speciation: Adaptive Radiation to fill empty niches

Endemic Terrestrial Species

Cladistic Analysis

• 1960s Development of Cladistic Analysis

• Determines Possible Pathways of Evolution

• Characters and Polarized Character States

• Anatomy, Morphology, Behavior, Chemical, Gene Sequence
• Plesiomorphies-Ancestral character states
• Apomorphies-Derived character states

• Construction of Cladogram-computers!

• Reveal homoplasies (parallel, convergent), reversals
• Most-parsimonious (fewest steps) cladogram
• Not necessarily unique!

Cladogram

Island-Hopping Crickets!

Amazing Fruit Flies!

• 511 of 2,300 endemic insects are drosophiloids

• DNA sequences show 10 MYBP arrived Necker

• Necker has subsided and lost habitat…now n=0

• All 511 endemic species are a single clade!

• Analyzed by morphology, karyotype, molecular analysis

Primitive Phylogram of Drosophiloids

Drosophilid Area Cladogram

Spiders Spinning Southeast!

Honeycreepers of Hawaii

How about Plants? Hibiscadelphus

Silverswords

Silversword Origins

• Closest relatives are California tarweeds

• 3,900 km open ocean crossing

• Fruits too thin-walled to survive bird gut

• Fruits do not float in sea water

• Fruits too heavy to float on wind

• Hairy and sticky sepals suggest bird attachment

• Preened off on Kauai, then radiated and migrated

Biotic Factors

• Symbioses (living together)

• Mutualism: zooxanthellae/corals/forams
• Commensalism: bromeliads on trees
• Parasitism: epiphytic woevine on shrubs

• Competitors: Epiphytes, Allelopathy, Exotics

• Herbivory

• Pollination, Seed Dispersal

• Partners required for reproduction

Abiotic Factors

• Light-wavelength (color), amplitude (intensity)

• Water absorbs low energy wavelengths…leaving blue
• Turbidity (milkiness) vs Turbulence (mixing)
• Chlorophyll (purple, blue, yellow, red)
• Carotenoids (green)
• Phycobilins (green to red) depending on type/depth

• Gas Availability (N2=78%, O2=21%, CO2<1%)

• Oxygen poisons photosynthesis (photorespiration)
• CO2 highly soluble in water, O2 virtually insoluble
• Most algae are C3, many terrestrials C4 or CAM

Abiotic Factors

• Temperature-plants are essentially poikilotherms

• Water in tidepools rises rapidly
• Eurythermal = wide tolerance, Stenothermal = narrow tolerance
• Dunes heat unless leaves shade them or burrow deeply
• Ice damage, frost, heat shock
• Large body size: thermal insulation vs heat load
• Surface:Volume ratio (Neither Fucus nor Ascophyllum here!)

• Desiccation: evaporation, osmotic stress

• Saccate thallus (Colpomenia or Valonia)
• Mucilaginous sheath, Waxy Cuticle, Hairy Epidermis

Abiotic Factors

• Salinity: osmotic stress, Na+ or Cl- toxicity

• Salinity in small tidepools rises with evaporation
• Salinity in small tidepools falls with rainfall
• Euryhaline = wide tolerance, Stenohaline = narrow tolerance
• Halophytes
• Exudation: Avicennia via hydathodes (salt glands)
• Exclusion: Rhizophora ion pumps keep salt out
• Shedding: Spartina, annual dicots, leaves abscise taking salt out
• Acclimitization: mannitol, sucrose, betaine, etc.

• Soil Minerals

• Oligotrophic Waters are Depauperate in Minerals (N, P, Fe)
• Eutrophic Estuarine waters: Algal Blooms

Abiotic Factors

• Surge Stress, Drag Stress, Shear Stress

• Turbulence in Rocky Intertidal
• Scouring in Sandy Intertidal
• Euryhaline = wide tolerance, Stenohaline = narrow tolerance
• Benefits
• Predator Restriction
• Parasite Removal
• Equalize Salinity and Temperature
• Adds CO2 for photosynthesis, but also adds O2
• Rhodoliths in deep waters…detached coralline red algae
• Phytoplankton in Photic Zone of open ocean only 5000 spp!
• Greater diversity and abundance in Estuarine waters