chpt 7&8 key concepts Flashcards
Asexual Advantages & Disadvantages
adv- offspring contribute wholly to fitness of parent
dis- mutation only variability
Sexual Advantages & Disadvantages
adv- creating gene variation
adv- purging harmful mutations
adv- increases variability
dis- costly to the individual (each offspring contributes only 1/2 fitness and they have trouble finding mates)
Cost of Reproduction for Males and Females
fem- more energetically costly gametes because they are larger
male- less energetically costly gametes because they are smaller
Limitations for Males and Females
fem- limited by resource access
male- limited by mate access
Conditions Favoring Hermaphrodites
low mobility
-limiting male to male competition
low overlap in resource demands by male and female structures
Principle of Allocation
organisms use energy for one function, the amount of energy available for other functions is reduced
Plant dispersers and seed size
seed size variation explains variation in plants
-larger seeds produce larger seedings
Six dispersal strategies
- Unassisted: no special structures
- Adhesion: hooks, spines, or barbs
- Wind: wings, hair, resistance structures
- Ant: oil surface coating
- Vertebrate: fleshy coating
- Scatterhoarded: gathered, stored in caches
Seed Size
small seed size
-variation has major implication for the performance of the offspring
-stay dormant longer
-seed unassisted by dispersal or wind
large seed size
-dispersed by hoarders
r-selected
per capita rate of increase
characteristic high population growth rate
K-selected
carrying capacity
characteristic efficient resource use
population attributes for r-selected
-a high intrinsic rate of increase
-not favored competitive ability
-rapid development
-early reproduction
-small body size
-single,semelparity reproduction
-many, small offspring
population attributes for k-selected
-low intrinsic rate of increase
-highly favored competitive ability
-slow development
-late reproduction
-large body size
-repeated reproduction
-few,large offspring
Grimes
proposed two most important variable exerting selective pressures in plants
Intensity of distrubance
any process limiting plants by destroying biomass