5.1 evidence of evolution Flashcards
what are factors that could contribute to changing environments? (4)
climate change
natural disasters
immigration/ emigration of a new predator or prey into/ out of environment
arrival of a competitor of the same food source
what do fossils show? (short ans)
the cumulative changes and development of traits
eg: physical and behavioural changes
how are fossils formed (long-ish)
form in sedimentary rock (eg: limestone and shale), forming layers or strata
dead organisms trapped in these layers and while soft tissues decompose, harder organic materials (eg bone or shells) can form different types of fossils
fossils slowly buried and pressed into the Earth
when examining sedimentary rock strata, older fossils typically buried deeper in the Earth than newer ones
→ scientists can place in chronological order
what is a homologous structure? + 1 example?
features in different species that are similar in position, structure and evolutionary origin, but not necessarily in function
eg: human arm + dolphin flipper
what is divergent evolution?
when two separate species have a similar structure but use it in different ways because of their environment
what is an analogous structure + 1 example
function similar but no similarity in bone structure or common ancestor
eg: fins on orcas and sharks
what is convergent evolution?
when organisms that are not closely related evolve similar structures that are used for similar purposes, often due to similar habitats or diets
DIFFERENCES between divergent and convergent evolution
DIVERGENT:
- shared ancestor
- structures look different + different functions
CONVERGENT:
- different ancestors
- structures resemble each other + same function
what is discontinuous variation and continuous variation + one example for both?
DISC:
distinct categories of gene variations, not affected by environment
eg: blood type
CONT:
wide range of characteristics for each trait, highly influenced by environment
eg: human height
what is speciation and how does it occur?
speciation, the process by which new species are formed from, occurs when two species become genetically different enough that they can no longer interbreed to produce fertile offspring
what is transient polymorphism and balanced polymorphism
transient polymorphism:
gradual change in allele frequency of a population due to the slow replacement of one gene of another
balanced polymorphism:
balance between both forms of the allele variations within a population
