Evolution Evidence (5.1) Flashcards
Define biological evolution
A change in the allele frequency of a population’s gene pool over successive generations.
Define microevolution
Small changes that occur over a short period of time and lead to the formation of new breeds or bacterial strains.
Define macroevolution
Large changes that occur over a long period of time and lead to the formation of new species and even phylum.
What provides evidence for evolution and how?
The fossil record because it reveals the features of an ancestor which can be used to compare against living descendants.
The Fossil Record
The totality of fossils, both discovered and undiscovered.
The Law of Superposition
Within a sequence of layers of rock, the oldest layer is at the base and the newest layer is at the top.
How does The Law of Superposition help us?
It allows us to relatively figure out the age of different fossils by dating the rock that it is fossilised in.
The Law of Fossil Succession
The ordered succession of fossils. It suggests that newer species likely evolved as a result of changes to ancestral species.
What are transitional fossils?
Intermediary forms that establish links between species by exhibiting traits common to both the ancestor and its predicted descendants.
How do fossils provide evidence for evolution?
By comparing hominin skeletons. Australopithecus first appeared in the fossil record approx. 4 million years ago. We can compare this fossil with the bone structure of homo sapiens today and see marked developments.
What is selective breeding?
Selecting specimens to breed based on the desirability of their traits. Artificial selection.
Outline two potential harms of selective breeding
Less genetic variation and inbreeding (this can cause health problems).
Define homologous structures
Structural similarities in groups of organisms that suggest they all share a common ancestor.
Define adaptive radiation
A type of divergent evolution. A common ancestor evolves into a large number of species to occupy distinct niches with different environmental conditions.
Give an example of homologous structures
The pentadactyl limb is seen in a variety of animals indicating a common ancestor. Mammals, birds, amphibians and reptiles all share similar appendage structures. However, these are all used for different forms of locomotion. Their common ancestor was early amphibians.