Ecology

[Deeisenberg]

rule of 70 for population growth

[dickyjones]

Rule of 69-72 is for finding doubling time. I usually just use the natural log function to do that.

If it's geometric growth and they give you 'r' and it's units. Multiply
'r' by the number of organisms at that time to find by how much the population will increase in one unit of time (dN/dt). That's only for populations with periodic (geometric) growth.

I haven't actually ever been asked for exponential and logistic growth other than graphing.
To find the total growth in exponential, use N(total)=N(initial)*e^(rt)...I remember it as 'Nert"
And in logistic growth, dN/dt (r) = max r*(1-N/K)...there's an equation to find total growth, but I don't remember it, and I doubt you'll need to know it.

Also r = b (birth rate) - d (mortality rate)...that's assuming no immigrants/emigrants. If they put those in there as well remember to add immigrant and subtract emigrants.

Natural selection is never very hard. Know what it is and be able to write an essay describing how it occurs. Also know the difference between directional, stabilizing, and disruptional. They probably won't get much more in depth than that.

[Bryant]

thanks a lot! but a few more questions, what does "r" stand for in the geometric growth? and what is the rule of 70? (I'm a Div B, so...)

[ScienceIsMyLife]

r stands for "rate" usually--its often in a percent that needs to be converted to a decimal

[Bryant]

i really need to work on my math more..thanks!

[ScienceIsMyLife]

no problem

soinc.org doesnt work correctly from my home computer and i cant access the links to study; any suggestions?

[Untrained_Doctor1]

try other internet sites (if you can)
or try basic biology books and go to the eco. section
usually that will give you all you need to know for the event
you may have to study biomes by finding a book on deserts or grasslands

[ScienceIsMyLife]

im working on it; this is the one event i really think i can do well in so im pouring a lot of time into the research this year. wish my partner would do the same!

[94]

My school got first place in the regionals for ecology.

My dad also made the test...

Made some people wonder...

Hahahaha

They deserved the win. Honestly.

[Liv]

omg I love ecology... well thats y i wanted to do it so i did[/size]