Adaptive Radiations and Evolutionary Change on the Hawaiian Islands Presentation By Diana Roberts June 3, 2003

Questions, Questions What are adaptive radiations and what criteria defines them? What role does evolution play in adaptive radiations and the rate at which they occur? What are some examples of adaptive radiations in Hawaiian birds, insects and plants? Why is adaptive radiation important to the speciation of animals?

Adaptive Radiations Adaptive Radiation is the evolution of a single ancesteral species into several new species within a relatively short amount of time in a specific geographic area Adaptive Radiations describe the process by which a group adapts to a broad variety of situations, such as changed ecological environment, dispersal barrier and lack of competition or preditors

Evolution Evolution is the process of change in the traits of organisms or their populations over time Evolutionary changes occur in populations as a result of genetic mutations that are passed to surviving generations or eliminated Natural selection can result in the formation of new species by promoting the species with the better advantage in the specific environment

Speciation Allopatric Speciation: Speciation that occurs when two populations that are geographically isolated from each other enough to diverge into different species Parapatric Speciation: Speciation that occurs when two populations that live in adjacent, bordering territories with no barrier between them diverge far enough to form different species Sympatric Speciation: Speciation that occurs when members of a single population, all living in the same environment diverge to form distinct species

Criteria for Adaptive Radiation Reproductive Isolation Ecological Isolation Exploitation of ecological niches- high islands good place because populations can be seperated by physical features such as water Disharmony of Island fauna and flora Rapid Speciation- “bursts” of new species Pollination Relationships with surroundings Dispersal Barrier, likely to radiate at or near the limits of the range of dispersal Variation in feeding and mating rituals Wide range in habitat and growth form

Hawaiian Islands

Hawaiian Island Adaptors Hawaiian Honeycreepers Hawaiian Fruit Flies (Drosophilidae) Pelia Silverswords Cytrandia

Hawaiian Honeycreepers - Drepenidiae

Honeycreeper Radiation Occupy an array of foraging and dietary niches which correspond with the variety of bill morphologies, variety and natural variation allowed random mutations to succeed at a higher rate because of the openness of niches during first colonization Repeated inter-island colonization allowed allopatric differentiation, followed by sympatric reinforcement and ecological divergence because of the lack of competing species and a broad variety of ecological niches Thought to have adapted like the Galapagose Finches, most common ancestor is thought to be the Eurasian Rose finch

I’IWI Vestiaria coccinea Found in the ‘ohi’a lehua forests Feed on the nectar of ‘ohi’a lehau flowers and tubular blossoms

‘APAPANE Himatione sanguinea Found in the ‘ohi’a lehau forest Feeds primarily on nectar, also feed on insects

‘AKOHEKOHE Palmeria dolei Feed mainly on nectar and seeds Found in the rainforests of Maui Endangered

PALILA Loxioides balleui Found only on the dry forest slopes of Mauna Kea Endangered Feed mainly on seeds

‘AKIAPOLA’AU Himignathus munroi Found only on big island of Hawaii Endangered Woodpecker like in they eat insect larvae by chipping away bark, also effectively eats the nectar of lobeloids

Hawaiian Fruit Flies-Drosophila 250 species of Drosophila are known, but numbers are expected to double 114 species of Scaotomyza on Hawaiian Islands, only 70 species are known on the rest of the world Isolation is thought to be the main cause of new species, preference to a particular host can isolate a species to where adaptive changes may occur

Hawaiian Fruit Flies Con’t Each species has individual preference for mating ceremonies and territories which involve factors of light, temperature, and humidity Differences in food sources- herbacous v. carniverous Body, wing size and shape

Cyrtandra Has formed the most diverse species on the Hawaiian Islands 129 species on Oahu alone Most vary in leaf and flower morphology, also fruit

Cyrtandra hawaienses Cyrtandra platyphylla

Cyrtandra cordifola Cyrtandra calpidecarpa

Geranium 50- 100 species known on Hawaiian Islands Occupy almost all of the habitats available to them Vary widely in leaf and bud morphology, also in growth form

Adaptive situations often cause plants to evolve the available pollinators, such as changing from insects to birds or vis versa

Overview Adaptive radiations are the process by which plants, animals, and insects adapt to their surroundings in a way that they form new species in a relatively short period of time Some criteria for adaptive radiation to occur is a dispersal barrier, ecological isolation, biological isolation,etc. Evolution of the Hawaiian islands has influenced the radiation of the plants and animals over the years because the islands have been moving and changing ecologically, pathing the way for adaptive radiation to occur

Examples of adaptive radiations can be seen in many Hawaiian species such as the Honeycreepers, Fruit flies, and the growth forms of Cyrtandra and Geranium Adaptive radiation is important to the Hawaiian Islands and many island alike because it increases the diversity of the wildlife, but with recent invasion of tourism and foreign plants and animals, the available area to be exploited by nature is decreasing, in turn not allowing as much diversification to occur

Bibliography Carlquest, Sherwin. Hawaii: A Natural History. Honolulu: SB Printers, Inc. 1980. Ch. 5. Carr, Dr. Gerald. U of Hawaii, Botany Department. http://www.botany.hawaii.edu Schulter, Dolph. The Ecology of Adaptive Radiation. Oxford U Press. Oxford, New York. 2000. Bermingham, Eldredge; Lovette, Irby J. Clade-specific Morphological Diversification and Adaptive Radiation in Hawaiian Songbirds. The Royal Society. 2001. U of Southwestern Adventist, Biology Department. http://biology.swau.edu