Biol 180 Quiz 3

Desiccation

loss of moisture

Life on Land

• Land plants have to avoid desiccation

• Increase CO2

• More sunlight

• Harder to stay upright (gravity

• Harder to transport gametes

Chordate

• Dorsal hollow nerve cord

• Notochord

• Muscular, post-anal tail

• Pharyngeal slit (sometimes)

Vascular tissue

transports fluids, nutrients, and structural support throughout the organism

Pollen

Cells that are encased in a tough coat of sporopollenin (wax); gives rise to sperm cells

Seeds

Embryo + food supply, surrounded by a tough coat

Notochord

flexible, rod-shaped structure; provides skeletal support

Dorsal hollow nerve chord

tube-like structure, forming primary central nervous system

Post-anal tail

Extension of body used for swimming and balance

Vertebrate Synapomorphies

• Vertebrae

• Cranium

• Jaw

• Amniotic Egg

Vertebrae

Stack of bones that form the spinal column, protects the dorsal nerve cord, more powerful movement and larger bodies

Cranium

Case that protects brain and sensory organs, supports complex brain

Jaw

Access to new food sources

Amniotic egg

Prevent drying out, provides nutrients and waste storage in compartments, improved reproduction away from water

Trends in human evolution

• Increased body size

• Decreased sexual dimorphism

• Bipedalism

• Smaller teeth

• Larger braincase volume

Out-of-Africa hypothesis

• Serial founders effect

• most genetic diversity in Africa

Monophyletic group

Common ancestor and all the descendants

Outgroup

taxon that is closely related to a monophyletic group, but not part of it; will be explicitly stated

Homology

Trait from a common ancestor

Homoplasy

Trait evolved independently of each other

Synapomorphy

Trait that is derived from an ancestor, unique to the monophyletic group

Parsimony

Simplest explanation is the most likely (least number of trait gains/losses)

Convergent evolution

Nature selection favors similar traits in similar environments

Phylogenetic Tree

Hypothesizes evolutionary relationship among species

Ancestral trait

characteristic from an ancestor

Derived trait

characteristic modified from ancester

Polytomy

Node depicting an ancestral branch dividing into 3+ descendant branches, indicating insufficient data

Root

Most recent common ancestor

Node

branch point where lineage splits

Branch

evolutionary path over time

Tips

Current species

Sister taxa

two lineages that split and are each other's closest relatives.

Cuticle

protective film that covers the plant, prevents dehydration and uv damage

Pore

tiny opening in the plant tissue

stomata

specialized pore that control trade-off of pulling in CO2 and losing H2O

Speciation

splitting event:

• genetic isolation - barrier to gene flow isolates 2 populations within a species

• genetic divergence - mutation/natural selection/drift occurs in an isolated population

allopatric speciation

speciation that begins with graphic isolation

dispersal

movement of individuals from one location to another

vicariance

physical splitting of a habitat

sympatric speciation

speciation when population lives in the same geographic area

disruptive selection

favoring extreme phenotypes, 2 subsets become genetically isolated

polyploidization

mutation that leads to polyploidy, typically in plants

autopolyploidy

mutation doubles chromosome number, chromosomes come from the same speies

allopolyploidy

parents of different species creates a non-sterile offspring with 2 full sets of chormosomes

Relliance on animal pollinators

coevolution

adaptive radiation

single lineage produces a large number of descendant species

serial founders effect

consecutive founder events that occurs when a population expands into new areas

reduce population growth

make life better for people who bear children

growth equation

birth rate - death rate + immigration - emigration