Explain competition (interspecific, intraspecific)

5.2.8 · Biology › Population & Community Ecology

Competition HAI KYA? (Definition — First Principles se)

Mechanism: Jab individual A resource R ki ek unit use karta hai, toh individual B ke liye R kam ho jaata hai. Isse ek negative feedback loop banta hai jo population growth ko slow karta hai jab density badhti hai.

Do Types: WHO compete karta hai, uske basis par

==Intraspecific competition== = competition within ek species ke andar (same species ke members compete karte hain)
==Interspecific competition== = competition between alag-alag species ke beech

Intraspecific Competition: The Family Fight

Derivation: Intraspecific Competition Population Growth ko Kaise Limit Karti Hai

Exponential growth model se shuru karo (unlimited resources):

$\frac{d N}{d t} = r N$

jahan $r$ = per capita growth rate (constant), $N$ = population size.

Problem: Yeh infinite growth predict karta hai. Reality? Jab $N$ badhta hai, resources per individual kam hote hain, toh $r$ ko decline karna padta hai.

Step 1: $r$ ko density-dependent banao. Sabse simple linear form:

$r_{a c t u a l} = r_{0} (1 - \frac{N}{K})$

jahan:

$r_{0}$ = intrinsic growth rate (maximum, jab $N \approx 0$ )
$K$ = carrying capacity (maximum $N$ jo environment sustain kar sakta hai)
$\frac{N}{K}$ = carrying capacity ka kitna proportion use ho chuka hai

Yeh form kyun? Jab $N = 0$ , koi competition nahi, toh $r = r_{0}$ . Jab $N = K$ , toh $r = 0$ (growth rukti hai). Jab $N > K$ , toh $r < 0$ (population decline karti hai).

Step 2: Growth equation mein substitute karo:

$\frac{d N}{d t} = r_{0} N (1 - \frac{N}{K})$

Yeh ==logistic growth equation== hai — intraspecific competition ka mathematical signature.

Worked example Worked Example 1: Yeast in a Flask

Ek lab culture of yeast $N_{0} = 10$ cells se shuru hoti hai. Carrying capacity $K = 1000$ cells hai, aur $r_{0} = 0.5 hr^{- 1}$ hai.

Calculate karo: Growth rate jab $N = 100$ , $= 500$ , aur $N = 900$ .

Solution: $N = 100$ par: $\frac{d N}{d t} = 0.5 \times 100 \times (1 - \frac{100}{1000}) = 50 \times 0.9 = 45 cells/hr$

Yeh step kyun? Jab population chhoti hai ( $K$ ka 10%), intraspecific competition weak hai — 90% resources abhi bhi available hain.

$N = 500$ par: $\frac{d N}{d t} = 0.5 \times 500 \times (1 - \frac{500}{1000}) = 250 \times 0.5 = 125 cells/hr$ $N = 100$ se zyada fast kyun? Competition strong ho gayi hai (sirf 50% resources bache hain), lekin badi population base ( $N = 500$ , 100 ki jagah) isse compensate kar leti hai. Yeh peak growth rate hai.

$N = 900$ par: $\frac{d N}{d t} = 0.5 \times 900 \times (1 - \frac{900}{1000}) = 450 \times 0.1 = 45 cells/hr$

Yeh step kyun? Competition intense hai ( $K$ ka 90% use ho chuka hai). Growth dramatically slow ho jaati hai bade $N$ ke bawajood.

Intraspecific Competition ke Mechanisms

==Exploitation competition== (scramble): Sabhi individuals ko resources tak equal access hota hai; woh bas consume karte hain. Sabko kam milta hai. Example: grass plants jo soil nitrogen ke liye compete karti hain — saari roots absorb karti hain, kissi ko poora nahi milta.
==Interference competition== (contest): Direct antagonistic interactions. Dominants resources monopolize karte hain; subordinates ko bahut kam ya kuch nahi milta. Example: territorial birds — winners breed karte hain, losers nahi. Hierarchies banti hain.

Worked example Worked Example 2: Tadpole Density Experiment

Ek ecologist tadpoles ko tanks mein 5, 20, 50, 100 per liter densities par rakhti hai. Woh metamorphosis par average mass measure karti hai:

Density (tadpoles/L)	Avg mass (g)	Survival (%)
5	2.4	95
20	1.8	88
50	1.1	70
100	0.6	45

Interpretation:

Mass decline = algae (khaane) ke liye exploitation competition. Density badhne par har tadpole ko kam milta hai.
Survival decline = jab competition extreme hoti hai, kuch tadpole starve kar jaate hain.
Yeh kyun matter karta hai: Kam mass → chhote frogs → kam reproductive success. Intraspecific competition population ko reduced fecundity aur increased mortality ke zariye regulate karti hai.