fundamental aspects of evolution

Question 1

macroevolution

Answer 1

• change occurring at or above the level of a species
• over long periods of time
• evolution of mammals and radiation of flowers
• phylogeny : the scientific study of evolutionary relationships among species
• phylogenetics : the study of relationships between organisms discovered through lines of evidence
• evidence : molecular sequencing; geology; fossils; living organisms
• phylogeny represented in a phylogenetic tree

Question 2

stasis / equilibrium

Answer 2

• don’t change for a long time
• some called living fossils even
• eg. coelacanth

Question 3

lineage-splitting (speciation)

Answer 3

• constructing and examining a phylogeny
• reference lines of descent and relationships
• cladogenesis : parent species split into two distinct species (clade)
• clade : life-form group consisting of common ancestor
• anagenesis : ancestral species gradually accumulate changes, eventually distinct from original species

Question 4

adaptive radiation

Answer 4

• burst of divergence from a single lineage
• gives rise to a new species from a single ancestor
• cladogenesis
• fills ecological niches
• eg. reptiles becoming truly terrestrial ; birds arose ; mammals become common

Question 5

extinction

Answer 5

• rare

- mass extinction only three types species survive

Question 6

what are some trends that occur in macro evolution?

Answer 6

• increased complexity

- increasing body size

Question 7

gradualism

Answer 7

• species evolve gradually
• small changes of long periods of time
• eg. human evolution

Question 8

punctuated equilibrium

Answer 8

• the speed at which evolution takes place
• not gradual
• some fossil species did not change over time
• short periods in which rapid changes occured
• absence of transitional fossils
• phenotypic modification occurs when species first branch off from parent species and little after
• extreme harsh conditions (volcanoes etc…) could increase evolution
• eg. snails