Ecological Population Dynamics

Transcription

1 Ecological Population Dynamics

2 Biotic potential The maximum number of offspring an organism can produce is its biotic potential. What keeps organisms from reaching their full biotic potential? Environmental limits (not enough food, water, shelter or things like disease, predation). These limits are called environmental resistance.

3 Population Growth Models Exponential model idealized Called r populations (J-curve) Logistic model realized Called K populations (S-curve) Which one happens most often? Why?

4 Strategies to increase biotic potential r-selected (opportunistic) Short maturation & lifespan Many (smaller) offspring No/little parental care High death rate EX:? K-selected (equilibrial) Long maturation & lifespan Few (larger)offspring; Extensive parental care Low death rate EX:?

5 Population limiting factors- Environmental resistance! Density-dependent factors: limited food water, shelter predation disease Density-independent factors weather/climate These factors lead to K* (*K=The max number of individuals an area can sustain/carrying capacity) Biotic potential vs Environmental resistance! (All life must deal with this) Leads to adaptation

6 More ways to increase success is to partake in Symbiosis. (2 unrelated organisms living close together.) Mutualism +/+ both species benefit Commensalism +/o one species benefits, the other is unaffected Parasitism +/- one species benefits, the other is harmed Neutralism o/o Neither organism benefits or is hurt

7 Types of competition: Intra-specific competition: occurs among organisms belonging to the same species. Inter-specific competition: occurs between organisms from different species (predator-prey)

8 Competition reduction Resource partitioning~ species consume slightly different foods or use other resources in slightly different ways (Develop niches) Character displacement~ sympatric species tend to diverge in those characteristics that overlap Ex: Anolis lizard sp. perching sites in the Dominican Republic Ex: Darwin s finch beak size on the Galapagos Islands

9 Predator/ Prey relationshipsspecial competition

10 5 Types of specific coloration adaptations: Aposematic coloration Stay away color Batesian mimicry copy cat, only 1 bad Mullerian mimicry 2 poisonous resemble one another Camouflage blend in Disruptive coloring obscures size or shape of organisms body.

11 All organisms characteristics and behaviors lead to increased survival. We can measure those outcomes.

12 Survivorship curve plot of numbers that Type 1 Death more likely at old age Type 2 Death equally likely at all ages Type 3 Death more likely at young age still alive at each age Where would you place k selected and r selected populations?

13 Big Changes in the system Primary succession- going from nothing (no soil)to pioneering community to climax community. Why would there be nothing??? Melting glaciers Volcanic eruptions Landslides Strip mines

14 Secondary Succession - Re-establish an ecosystem after a disturbance What could be a possible disturbance? Flood Fire

15 Geographic dispersion of a population shows how individuals in a population are spaced. Population dispersion refers to how a population is spread in an area. (Density) Clumped dispersion Uniform dispersion Random dispersion

16 Random Sampling Take the area you are analyzing. Divide it into equal quadrants. Randomly select a specific number of subdivided quadrants, count all organisms in those areas. Add up all organisms counted, divide by # of quadrants than X by total quadrants. 8/4=2 X16=32 Actual = 26 PROBLEMS?

17 Capture mark-recapture (Lincoln-Petersen index) In a given area, capture a specific number of organisms, mark them and release them back into the wild Over a set amount of time, recapture a preset number of organisms and keep track of how many have already been captured. (They have marks) Use math to estimate total population in an area. Problems?