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Origin of Species

Intro | Storm | Pollenpeepers' New Homes | Windsor Island | Warwick Archipelago | Gallery

As you will see, on the Warwick Archipelago, the founding population will diversify into several distinct species in a manner consistent with the adaptive radiation history of the Hawaiian honeycreepers and similar groups elsewhere in the world. The diversity of habitat on the islands in this archipelago provides more opportunity for divergence than does the less diverse mainland. Also, the distance from the mainland makes immigration difficult, leaving dozens of niches available when the pollenpeepers arrive. Follow along to explore what happens to the Warwick Archipelago pollenpeepers.

Warwick Archipelago: 5 Million Years Ago

Highlight

  • Nearly 150 pollenpeepers arrive on largest island.

Pollenpeeper changes

  • As the hurricane loses its intensity, nearly 150 pollenpeepers are carried by the storm to the largest island of the Warwick Archipelago, an island chain 600 miles northeast of the mainland.
  • The group settles on the north side of the island, where the habitat is most similar to the pollenpeepers' mainland home.

Habitat

  • A very high ridge divides the large island the pollenpeepers now occupy.
  • The north side of the island has a lush, wet habitat on the coast; the island's south side is desertlike, receiving less than half the rainfall of the north side.

Food

  • Seeds
Many seeds available
  • Insects
Few insects available
  • Flowers
No nectar flowers available

Competition

  • There is virtually no competition for the new immigrants when they arrive on the island. The only other bird on the archipelago is a species of hummingbird that lives in the high alpine forest of another island in the Warwick chain.

Predators

  • Very few predators threaten these pollenpeepers

Warwick Archipelago: 4 Million Years Ago

Highlight

  • The population grows quickly and pollenpeepers begin dispersing.

Pollenpeeper changes

  • The population on the north side of the largest island grows gradually.
  • Dispersal from the large island to other islands in the chain is rare, though, due to the low population density on the large island, the small size of other islands in the chain, and the distance between the islands.
  • There is very little change in the appearance of pollenpeepers on the island chain.

Habitat

  • Initially, the pollenpeepers settle along the coast of each island -- the coastal habitat is most like that of their original mainland home.
  • As individual populations grow, small groups expand their ranges, dispersing slowly into other areas.

Food

  • Seeds
Many seeds available
  • Insects
Some insects available
  • Flowers
Few nectar flowers available

Competition

  • There is very little competition among pollenpeepers. When competition does arise, some members of the population move to another area or to a slightly different habitat.

Predators

  • Very few predators threaten these pollenpeepers

Warwick Archipelago: 3 Million Years Ago

Highlight

  • Isolation on high mountains causes rapid change in one population.

Pollenpeeper changes

  • The first pollenpeeper group to become significantly isolated and differentiated from the others is a population occupying the highest alpine mountains of one of the middle islands in the chain.

Habitat

  • The alpine mountain habitat of the newly isolated population is very high, cool, and wet, with a short growing season. Flowers are plentiful seasonally, offering pollen and nectar to insects and birds.

Food

  • Seeds
Some seeds available
  • Insects
Some insects available
  • Flowers
Some nectar flowers available

Competition

  • Competition among different populations of pollenpeepers remains low throughout the archipelago.

Predators

  • Very few predators threaten these pollenpeepers

Warwick Archipelago: 2 Million Years Ago

Highlight

  • Populations diversify rapidly in response to new conditions.

Pollenpeeper changes

  • Populations of pollenpeepers become established and relatively isolated in each of the archipelago habitat types: coastal scrub, desert, lowland forest, and high alpine forest.
  • The coastal pollenpeepers develop short, wide beaks, perfectly suited to eating seeds. They remain fairly drab; males develop a muted reddish breast when they reach maturity.
  • Desert pollenpeepers develop short, wide beaks similar to those of the coastal birds. Their plumage, however, begins to distinguish them from the coastal birds: Both males and females begin to show dramatic red, yellow, and black plumage.
  • Lowland forest pollenpeepers develop beaks specialized for picking insects out of tree bark. Their feet and tails become well adapted to this type of foraging, too, allowing them to cling to the trunks of trees. Both males and females develop very dark body plumage, accented by brilliant white wing patches. Some males begin to show the beginnings of a red head crest, which females highly prefer.
  • The beaks of alpine forest pollenpeepers become longer and narrower, allowing the birds to probe inside flowers for insects and, increasingly, flower nectar. The plumage of the males is becoming a brilliant iridescent green.

Habitat

  • The island chain continues to offer an extremely diverse set of habitats, from low, dry desert to high-elevation alpine forest. Each habitat type has its own best food source for pollenpeepers.

Food

  • Seeds
Many seeds available
  • Insects
Many insects available
  • Flowers
Many nectar flowers available

Competition

  • Not long after the pollenpeepers arrived on the archipelago, there were countless available habitats for groups to move into when competition in a preferred habitat got too intense. Now, available niches are dwindling.

Predators

  • Very few predators threaten these pollenpeepers

Warwick Archipelago: 1 Million Years Ago

Highlight

  • Lowland forest population begins feeding on nectar.

Pollenpeeper changes

  • Coastal pollenpeepers specialize in cracking the shells of seeds quickly and efficiently using their wide, heavy beaks.
  • The beaks of desert pollenpeepers look very much like those of the coastal birds, only slightly heavier and shorter. The desert birds, however, distinguish themselves with their flashy yellow, red, and black plumage.
  • Lowland forest pollenpeepers develop a long, sharp, and slightly down-curved beak that allows them to most efficiently find and retrieve beetle larvae and moths under the bark of trees. This beak also allows the birds to feed on flower nectar where flowers are plentiful. Their plumage becomes darker, except for the brilliant white wing patches and the males' red crest.
  • Alpine forest pollenpeepers do well with their long, sharp, sickle-shaped beak. It is perfectly suited for obtaining nourishment from one of the island's most plentiful flowers, a relative of the hibiscus that hides its nectar deep within curved, tubular flowers. The brilliant iridescent green of the males is also highly selected by females; over successive generations, it becomes more intense.
  • Some of the lowland forest pollenpeepers expand their range to higher elevations as their preferred habitat creeps higher. They are different enough in color and size from other pollenpeepers that as they encounter alpine forest pollenpeepers, they do not interbreed with them. They do, however, compete with them for food.

Habitat

  • A climate change on one of the islands causes the boundary between two populations' habitats to shift. Shrubs from the lowlands encroach on and out-compete some of the lowermost alpine forests, resulting in a replacement and mixing of habitat types.

Food

  • Seeds
Many seeds available
  • Insects
Many insects available
  • Flowers
Many nectar flowers available

Competition

  • As lowland forest pollenpeepers expand into the habitat of the alpine pollenpeepers, the two populations begin competing with one another. Lowland forest birds now feed preferentially on nectar in this habitat.

Predators

  • Very few predators threaten these pollenpeepers

Warwick Archipelago: Present

Highlight

  • Six distinct populations occupy the archipelago.

Pollenpeeper changes

  • There are now six distinct populations of pollenpeepers on the archipelago and four clearly defined species. The four species have become specialized in the way they find food and other resources. They are now genetically isolated from one another, meaning that they do not interbreed successfully with any of the other species. The distinct populations that are not yet distinct species continue to diversify from one another and will likely soon be.
  • The pollenpeepers that most recently moved from the lowland forest into alpine pollenpeeper habitat maintain a tenuous hold on survival given the competition of the more established birds. In response to the competition, both the newest arrivals and alpine species are diverging further from one another, eliminating overlap in their behaviors and the resources they use.
  • Alpine birds now have extremely long down-curved beaks, which allow them to obtain nectar from the deepest flowers -- an adaptation they did not have before the birds from the lowland forest arrived.
  • The new arrivals from the lowland still feed on flower nectar they can reach with their relatively short beaks. These flowers contain less nectar than the deeper flowers, but they also attract pollinating insects, for which the lowland birds have no competition.
  • A portion of the desert population occupying the east end of the archipelago moves to a new island that has formed. They are best suited to the hot, dry, sparsely vegetated environment they encounter there.

Habitat

  • A new island has formed on the east end of the archipelago. For several hundred years, the island sits quietly barren. Periodically seeds are carried ashore by pollenpeepers and ocean currents, and plants begin to take hold across the island.

Food

  • Seeds
Many seeds available
  • Insects
Many insects available
  • Flowers
Many nectar flowers available

Competition

  • Competition has been reduced temporarily. Cohabitating populations like the lowland and alpine pollenpeeper species have become more distinct from one another, specializing to a point where the overlap between them is reduced.

Predators

  • Very few predators threaten these pollenpeepers

-> Explore the gallery

Intro | Storm | Pollenpeepers' New Homes | Windsor Island | Warwick Archipelago | Gallery

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