Angiosperms pt 2

Sexual reproduction

• takes male and female genetic material and combines them (often sperm and egg)

  • meiosis and fertilization

Asexual reproduction

• involves clones (genetic copies); in plants, this is also referred to as propagation

  • mitosis

What are some ways that plants are propagated asexually?

• grafting

• tree “suckers”

• Vegetative structures

  • (roots, stems, buds, leaves)

Grafting

asexual reproduction

stolons

above ground

rhizomes

largely underground

tubers

swollen roots

bulbs

swollen leaf bases

Why is sex beneficial for a species?

diversity and more likely for survivial with variation in the population

Sexual reproduction → Recombination:

making new genetic combos (not the same as mutation)

Recombination shuffles allele combinations

• During meiosis (gametes), homologous chromosome pairs can swap alleles

• Allelic combinations get shuffled

“Selfing” vs. “Outcrossing”

Which is sexual reproduction?

-both

Which promotes/increases genetic diversity in a population/species?

outcrossing

self crossing

self pollination

• 10-15%

• leads to genome-wide homozygosity, which can cause inbreeding depression (reduced fitness)

outcrossing

cross pollination

• pros:

  • genetic diversity

  • resilient to disease

  • likely to adapt

• cons:

  • relying on other organisms to reproduce

  • no guarentee of improvement

monoecy vs dioecy, which promotes outcrossing?

dioecious

• forces pollen to travel to a diff plant

• strictly

t-value

Quantifies the rate of outcrossing for a species

• 0 = 100% of offspring result from selfing

• 1 = 100% of offspring result from outcrossing

• 0.2 = 20% of offspring from selfing, 80% from outcrossing

• 0.5 = 50% of offspring from selfing, 50% from outcrossing

Wind pollination

(could result in selfing OR outcrossing)

• pros

  • spend energy on attracting pigments

  • if specialized with 1 pollinator that goes extinct(species dies off)

  • pollinators are seasonal

• cons

  • less energy wasted on pollen

  • pollen likely to hit target

  • disperse further

  • when no pollinators, might be able to self

Animal pollination

(could result in selfing OR outcrossing)

• pros

  • less energy wasted on pollen

  • pollen likely to hit target

  • disperse further

  • when no pollinators, might be able to self

• cons

  • spend energy on attracting pigments

  • if specialized with 1 pollinator that goes extinct(species dies off)

  • pollinators are seasonal