Plant reproductive strategy evolution! Flashcards
(37 cards)
what are key survival challenges for sessile organisms?
structural support
reaching reproductive partners
preventing desiccation
dispersing offspring
what does sessile mean (sorry lads i genuinely forget this sometimes)
immobile in the way that its fixed in one spot
when did angiosperms evolve?
around 135million y.a
Key terms: What is a sepal?
AKA calyx, outer part of flower (leafy green structures) outside of flower bud.
key terms: what are petals?
AKA corolla, petals tend to make up the bulk of the flower. numerous and individual, may be fused
key terms: what is the stamen
AKA andoecium, structure that produces pollen, typically consisting of an anther and filament (male bit)
what the literal freak is the Carpel? do tell me what it is please im quite frankly DESPERATE to know. so tell me. now. please.
AKA Gynoecium, female structure, composed of ovary, style and stigma
whats a tepal
Early flowers had these!
basically a sepal petal mish mash on the outer whorl of flower
over evolutionary time, how did angiosperm structure change?
now guys, this is a big un of a flashcard but ill break it down more into lots of little cards too
Flowers became generally less complex, more aligned with a common format.
Floral structures simplified and flattened from complex spiral arrangements to simpler symmetrical arrangements.
Radial symmetry became less common compared to bilateral symmetry (helped by petal fusion)
Carpel tended to be inferior to flower rather than superior.
Early flowers had complex and diverse anthers, another format simplified and standardised more.
Development of nectaries - WITH INSECT EVOLUTION
Carpels were generally very primitive in early angiosperms. Sometimes only modified leaves.
how have petals evolved over evolutionary time?
Later development divided Tepals into PETALS and SEPALS
Petal FUSION occurred later in evolutionary lineages as flowers specialised, and petals
gained specific functions to encourage pollenators (e.g. petal tubes, asymmetric shapes, mimicry)
why did plants need to evolve to adapt to dry land?
As they were originally aquatic, this move to land caused a need to be able to act independent of water! Previous species were highly dependent on water for survival and reproduction
adv & disadv of wind pollenation
adv
- continuous process
- not reliant on another species
- long distance spreading!
disadv
- no directionality
- need a LOT of pollen
- needs a sticky stigma to catch
- most effective in close range
- chances of actually finding target is very low xoxoxo
how are seeds and pollen evolutionary adaptations to dry land?
Pollen grains are male gametophytes and may be carried by wind water or a pollinator! they are protected from desiccation as they arent dependent on water for fertilisation. they grow a pollen tube to reach female gamete (in cycads, “sperm” possess flagelle that allow them to swim down pollen tube to female gamete)
What are the advantages of pollen and seeds?
Pollen enables reproduction without reliance on water & resistant to desiccation, light and easily transferred, adaptable
seeds offer protection, dispersal and enable dormancy periods
adv and disadv of pollenator pollenation
advantages
- highly efficient
- large distances
- high volumes of pollen transferred
- less pollen required
- more certainty of pollenation
disadvantages
- costly ( energy wise i reckon) to produce floral structures
- requires development of complex structures
- requires species loyalty
- resource vs benefit
- seasonal reliance on pollenator
how would you describe the relationship between pollenators and plants?
Mutualistic
what mechanisms have evolved to attract specific pollinators
colour, scent, nectaries
- flowers may be uniquely structured for mouthparts/senses of specific pollinator
shaped specifically to cover pollinator in pollen
how does climate influence plant evolution?
Alters evolutionary pressures. A warming environment will need to lead to changes in floral structures, flowering times, species re-adaptation
how does urbanisation influence plant evolution?
changing conditions and ecosystems require adaptation to changes in plant distribution and pollinator availability
modern influence on plant evolution: hybridisation by humans
subspecies hybridise easily
movement of plants and seeds around world increases chances of hybrids being formed
keep going youve got this!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
youre clever and hard working and amazing
When did land plants evolve?
Around 475 MYA
