Formation of new species

Question 1

What is speciation?

Answer 1

formation of new species that are genetically distinct from the older parental species.

due to one species dividing into two or more species - Cladogenesis.

Question 2

What causes speciation?

Answer 2

Each population contains genotypic variations.
Variations increase species chance of surviving under different conditions .
Variations lead to two types of speciation - GEOGRAPHIC (allopatric) and SYMPATRIC.

Question 3

What is Geographic (allopatric) speciation?

Answer 3

Occurs when new species is formed as a result of the whole or part of a population becoming geographically isolated from ancestral species.

Question 4

How do populations become geographically isolated?

Answer 4

• rivers changing course, moutains rising, continents drifting, organisms migrating

Today geographic speciation can start when:

• lake dries,forming two separate bodies of water
• seeds stuck on bird, fall on new island
• sea currents wash lizard/insects to new island.

Question 5

How did ancestral finch group find their way to the islands?

Answer 5

driven by strong winds, from nearest mainland , 1000km away landed on one of the islands.

Question 6

What are finches?

Answer 6

sparrow-sized, similar in appearance but they are in beak structure and feeding habits

Question 7

How did the different species arise?

Answer 7

finches isolated on South American mainland and were free to evolve because there was:

• an absence of pre-existing predators
• no competition from other land birds as there were none there.
• A variety of ecological niches, each with its own type of food.

Question 8

What are the stages in the speciation process?

Answer 8

1. Division of habitat
   - finch sepecies divided into two lineages each occupying different habitats. > Ground and tree finches
2. Division of food resources by trophic specialisation
   - as pop grew, food scarcity comp for food increased
   - large variety of feeding niches open, early species developed feeding specialisations to get food from different sourcs.

e.g
-grasping beaks, tree finches > eat buds, fruits and insects
-crushing beaks, vegetarian finch> eat seeds,/ ground finch, eat tick and blood of sea creatures
- probing beaks ,cactus finch,. Probes cactus fruit for seeds
woodpecker finch, ues small twigs and cactus spines to poke into crevices in dead branches for insect larvae.

Question 9

What changes in the environment that allowed species to change?

Answer 9

• empty ecological niches each with its own type of food,provided opportunities for change.
• comp during food shortage,provided selective pressure/needs for change.

Question 10

How did Baobabs arise?

Answer 10

• found naturally in Madagascar (6 species), Africa (1 species) and Australia ( 1 species)
• Madagascan species occur in deciduous forests.
• Baobab arose after splitting up of Gondwanaland , so different ideas about point of origin ie where ancestral species existed.
• Madagascar, point of origin , with diversification into six species
• reached Africa by water dispersal

Question 11

What might have caused speciation?

Answer 11

Baobab flowers open at night with pollinators visiting to feed on the nectar.
Madagascar,pollinators are Lemur and Moth
-animals not in Africa, had to be an environmental to help plant adapt
- variant arose that might have produced nectar that suited bats.
-selection might favoured those trees, way speciation could have taken place.
- trees grow at fair distance as bats are long distance pollinators.

Question 12

What is a speciees

Answer 12

A group of organisms that are able to breed amongst themselves but with not with any other species, and produce viable offspring.