Key Points and trends in Plant Evolution Flashcards
Name the 12 points of evolution
- Many adaptations may no longer be adaptive
- Gene numbers may roughly reflect organismal complexity but genome size does not
- Symbiosis has, in some cases resulted in new “designs” leading to major evolutionary lineages
- Evolution is not a particularly linear or sequential process
- Different “advanced” characters may be found in different groups and need not go together
- Phenotypes can evolve backgrounds (simplified) or be repeated, among different lineages or within a single lineage.
- Pre-existing adaptations/structures may become modified into new adaptations/structures in whole or in part
- In the Plantae, there has been a trend towards increasing dominance of the sporophytic generation over the gametophytic generation.
- There has also been a trend towards increased protection of the embryo.
- Roots and shoots have evolved in different ways
- Leaves arose in at least two ways
- Floral evolution shows 4 main trends.
Explain “Many adaptation may no longer be adaptive”
Plants may be adapted to be dispersed by a now extinct animal
Mechanism is no longer useful
Ex. giant sloth
Explain “Gene numbers may roughly reflect organismal complexity but genome size does not”
Some plant genomes are huge but a lot of the material do not correspond to genes
Ex. Some plants have more genomes than humans but that does not mean they are more complex!
Explain “Symbiosis has, in some cases resulted in new “designs” leading to major evolutionary lineages”
Ex. chloroplasts and mitochondria
Organelles originated from bacteria cells
Explain “Evolution is not a particularly linear or sequential process”
Lacks direction and full of branches that split apart or sometimes come together
Explain “Different advanced” characters may be found in different groups and need not go together”
Species may be “primitive” in one respect but highly evolved in another
What is convergent evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time
What is an example of convergent evolution?
An example of convergent evolution where lower branches of numerous New Zealand shrubs and trees in 18 unrelated families are densely forked and twisted
What are sporophytes?
The generation that produces spores
What are gametophytes?
The generation that produces gametes.
What are embryos in relation to plants?
Young sporophytes that are diploid
What is sporangia?
Where the haploid spores produces by sporophytes in meiosis are released on stalks or undersides of leaves.
What is the ovule?
The female gametophyte with archegonia to make eggs, surrounded by tissue from the sporophyte.
How do angiosperms reproduce?
Sporophyte developed into ovaries surrounded by ovules.
What does monoecious mean?
Both male and female reproductive features are on one individual
