Task 13

Write down everything you can remember about mutations? What types of mutations are there and what are the consequences of mutation? Focus on the "benefits" of mutations. Explain how a DNA mutation can result in a phenotypic change.

Suggested answers are shown on the Jamboard below:

Task 14

Decide on a suitable example to explain the process of natural selection and evolution.

Darwin's Finches

"The most curious fact is the perfect gradation in the size of the beaks in the different species of Geospiza, from one as large as that of a hawfinch to that of a chaffinch, and … even to that of a warbler…. Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends" (Darwin 1839, pp. 379–380).

One of the classic examples of adaptation via natural selection is the evolution of 15 closely related species of finches, differing in their size and shape of their beaks. Charles Darwin, as part of the Beagle expedition, collected these birds on the Galápagos Islands in 1835 and introduced them to science. Darwin's finches perfectly illustrate speciation, natural selection and niche partitioning.

High above the cliffs of the Darwin Bay on Isla Genovésa (Tower Island) are small black and brown birds. These birds look similar to each other in plumage and song, yet closer observation reveals that they all differ from one another in how their beaks look and work.

• Warbler finch (Certhidea fusca) - has a very thin and pointed beak, which is used to probe leaves of the palo santo trees to catch small insects and their larvae.

• Another species feeding nearby on a small bush is the sharp-beaked finch (Geospiza difficilis), which has a slightly larger and more cone-shaped beak that is used to collect a more varied diet of both insects and small seeds.

• On the neighbouring small island of Wolf, members of the same species (G. difficilis septentrionalis) use their sharp arrowhead-shaped beaks to cut wounds on large sea birds, such as the Nazca and blue-footed boobies, and drink their blood.

• Two larger species of finches on Genovésa feed and nest in close proximity to the warbler and sharp-beaked finches. One of them, the large ground finch (G. magnirostris), has a massive, extremely deep and broad bullfinch-shaped beak that can be deployed to crush the large and hard seeds that no other bird on the island can handle.

• Lastly, there is the large cactus finch (G. conirostris) that has a more elongated yet still robust beak adapted for penetrating the firm covers of cactus fruits and closed cactus flower buds that contain protein- and sugar-rich parts inside.

All these species and 10 more across other islands of the Galápagos archipelago and Cocos Island do not belong to different families, as their extreme differences in beak morphology and specializations would suggest, but are all part of a tightly linked and relatively recent group that diverged within the last 2–3 million years called Darwin's finches (formerly known as the Galápagos finches).

See: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2830240/ - for full article.

Task 16

Use your understanding of the Founder Effect to explain the diagram opposite. What does it show and how does this impact evolutionary change?

The Founder Effect is the reduction in genetic variation due to a division in an original population; this division involves a small subset of the original population becoming isolated from the original one. The original population would have a particular proportion of each phenotype. But, following division, the new population might not represent the spread of variation in the original population. This is "genetic drift" where random changes, not influenced by selection pressures exerted by the environment, alter the proportion of alleles found within a population. This can impact evolutionary change in that the new phenotypes might not be the best suited to the new environment - this was a random event and might impact the overall success of the new population in the new environment.

Task 17

Outline selection pressures faced by the iguana. What impact did this have on their survival?

Task 19

Describe one example of each symbiotic relationship we have explored - be very clear on why each has been assigned (+/+), (+/0) or (+/-)

Mutualism - In the example shown, the relationship is classed as +/+ because both the fish and shrimp gain from the relationship - the fish gains shelter and a place to lay eggs (provided by the shrimp) and the shrimp is protected by predators that it cannot see (provided by the fish who taps him on the back when predators are near!).

Commensalism - in the example shown, the relationship is classed as +/0 because only one of the organisms in the relationship benefit while the other is unaffected; the hermit crab requires the snail for its shell, but the snail is unaffected by this because it has died. The mites hitch a ride on insects, which are unaffected by the tiny organism.

Parasitism - parasites often have a negative impact on their host by claiming resources as their own, e.g. hijack the host digestive system and impair its function for the host itself; in doing so, the parasite benefits (+) but the host suffers (-).

Task 20

Conduct your own research into co-evolved pairs of species that have not been mentioned above. Your response must include:

1. a co-evolved herbivore and plant relationship

2. a co-evolved pollinator and plant relationship

3. a co-evolved predator and prey relationship

4. a co-evolved parasite and host relationship