Summary: Ecology
- This + 400k other summaries
- A unique study and practice tool
- Never study anything twice again
- Get the grades you hope for
- 100% sure, 100% understanding
Read the summary and the most important questions on Ecology
-
Ecology
This is a preview. There are 85 more flashcards available for chapter 11/04/2015
Show more cards here -
Four Aspects of a Species' Life History
1. Metamorphosis- Organisms undergo radical changes in morphology, physiology, and ecology over the course of their life cycle.
2. Diapause- Presence of a resting stage somewhere in life cycle
3. Senescence- Process and timing of aging and death of an organism and why
4. Reproductive Patterns- Magnitude and time of reproductive events
-
Metamorphosis Ecological Advantages
1. Reduces Competition (w/n species)- Different niches
- Higher # in given habitat
2. Easy to exploit predictably variable habitats (predictable transient life cycle)- Compartmentalize Life Stages (can predict when habitat/resources w/n the habitat will disappear)
- Young: feeding & growth
- Adult: dispersal & repro.
- Use transient resources
- Body plan changes to match other needs in the life cycle
-
Strategies in harsh Unpredictable environments
1. Resistant stages at set time intervals (doesn't really take environmental cues but time intervals "like ticking of a clock")- Ex. Freshwater sponges
2. Multiple young in different developmental stage simultaneously- Ex. Kangaroos having multiple babies a different developing stages
3. Accelerated Development + Diapuse- Conditions harsh for long periods --> organism in diapause
- Favorable conditions occur infrequently & last a short time
- Compressed lifecycle
- Harsh conditions --> diapause (Spadefoot Toad)
-
Evolutionary Senescence Model
- "bad" mutations affecting young: strongly selected against
- Bad mutation affecting old: persists (don't impinge on the fitness of the organism; doesn't affect the next generation)
- Antagonistic Pleiotropy: Genes, which benefit early reproduction, have deleterious effects later in the lifespan. (Deterimental to older individuals but good for younger individuals)
-
Mortality and Reproductive pattern
Increase survivorship or decrease reproduction
Decrease survivorship or increase production -
2. Present vs. Future Reproduction
Reproductive value: Vx = (mx) (lx)- decrease reprod (mx) >> increase Vx (& vice versa); if fairly low, then each individual is important
- increase Survival (lx) >> decrease Vx (& vice versa); each individual isn't as valuable, b/c they don't have to replace and individual as soon.
Increase Reproduction --> Decrease Survival- Optimal strategy balances: Benefit of reproduction now vs cost of future reproduction.
-
3. Age at Sexual Maturity
Natural Selection favors maturity at Early Age- More you can have over life
- Low adult survival
- ++ if semelparity species (But most species do not have offspring at a young age)
When delayed reproduction is favored- High adult survival (invest yourself)
- Reproductive success dependent on age, size, experience, etc. (male elk defending his harem)
-
Theory of r and K (selection) species
- Classification
- For Each, distinct strategies evolve
- Bet-Hedging strategy
- Classification
-
For r & K, distinct strategies evolve
r species- Natural selection favors E energy invested in reproduction over competitive ability (quick turnover rate)
K species- Natural selection favors E energy invested in competitive ability over reproduction (can compete better; Maintenance over reproduction)
-
Grimes' Plant Life History Strategy
1. Environment variations ---> variable strategies
2. Matched plant strategy with environment
- Higher grades + faster learning
- Never study anything twice
- 100% sure, 100% understanding