Unit 7 - Population Biology and Impact

What is symbiosis ?

no organism exist in isolation and species interaction involve occasional or indirect contact (predation or competition) or involve close assosciation or symbiosis

ecompasses a variety of interactions involving close species contact . Comselism , paratism , mutualism

effect population density and comunity structure . even allelopathy determine species presence or not

what are symbiotic relationships ?

Symbiotic relationships, or symbiosis, describe close interactions between two different species where one or both organisms benefit from the relationship.

mutualism

initimate association 2 species with advantage to both

Ex: lichen result of a it between fungud and an alga ‘

termites and thier ceelulose digestjng bacteria

EX: ruminants have mutualistic reltioshop with gut microflora where bith iffer advantage

parasitism

exploitative relationship in plants and animals. parasite exploite resource of host for own benefit. host harmed not killed

Ex: tapeworms live in host and attack suckers to host tissues

ticks sucj bodily fluids cause disease to host

EX:

commensalism

one is the commensal which benefits and other is neither harmed or helped

ex: large grouper and remora

anemone shrimp commensal with sea anemone (shrimp gains by being protected from predators by anemone’s tentacles

competition

resources dominated by largest mist agresive , both harmed

hyenas compete for carcass with vultures

fish picking decaying food from teeth of larger fish

mutualism(cleaner fish, grouper)

ringworm in child’s neck growing

parasitism (ringworm,child)

humans planting cabbages tp eat but eaten by slugs

consumption (humans,slugs)

shrimp gets food scraps and protection from sea anemones apear unaffected

comensalism

birds follow antelopes to feed off insects , and antelopes of danger by irds

mutualism

cohesive group benefits

increased protection, from predators, and reduce energy expenditure during movement.

1)stay with group while away from predator 2)without collisions 3)movement aligned

Schools perform hydrodynamic stays always in tight groups and knowing each others movement. = reduce individual capture , cause confusion , more prey to be eaten - (predator satiation), predator detection

Seperate roles like fetting food and looking at predators =many lookouts , driven by individual needs

distance between each and loosely organized =maximiser food intake and home

cooperative interactions

enhances survival like ore accurate migrations, increased outcome of successful kill, risk to individuals decreased and altruistic behavior of disadvantaged taking care of others

population dispersion/distribution patterns

the pattern of distribution or dispersion of the individuals of a population , species behave and how distribution and abundance of environmental resources can affect them

distribution pattern : clumped

animals that I've in family units , insects that live in plants (otters, lions)

distribution pattern : uniform

territorial animals , plants that compete for access to water. (saguaro cacti)

population pattern : random

plants use wind dispersal and solitary animals that are-territorial

population size

smaller population are more at risk of inbreeding , genetic mutation and genetic drift

population density

the # of individuals in a defined area(closely packed) , more likely to encounter aphate and successfully reproduce . however infectious disease can spread .

exponential growth

unlimited resources . Initial lag where start reproducing , in bacterial colonies

logisic growth

limited by natural resources and space , reaches carrying capacity after lag.

seen in all stable populations in fixed area

human population growth

due to industrial revolution the population went from 1 billion . exponential wont last forever increase levels of education lead to lower birth rates . will stabilize

density independent limiting factors

abioctic factors , affect regardless density

natural disasters , severe matter, pollution

density dependent limiting factors

biotic (living) factors . affect depend on density

predation

spread of disease and parasites

competition

intraspecific competition

between members of own species , more intense as same niche

interspecific competition

between members of different species , less intense p

predator -prey cycles

prey population increased due to few predators

predator increase due to high numbers of prey for food

lag period between increase in prey and the increase in predators and takes time for predators to grow and reproduce

Q: How does intraspecific competition affect population growth?

A: It regulates population size by limiting growth as resources become scarce, leading to density-dependent regulation and self-thinning.

Q: How does intraspecific competition influence population distribution?

A: It can lead to evenly spaced individuals (uniform distribution) or clustering in resource-rich areas.

Q: How does interspecific competition impact population growth?

A: It can cause competitive exclusion, reduce population sizes, or lead to niche differentiation to coexist.

Q: How does interspecific competition influence distribution?

A: It causes habitat partitioning and range limitations, with species occupying different niches to reduce competition.

Q: What role does competition play in population regulation?

A: Both intraspecific and interspecific competition are density-dependent factors that regulate growth and distribution.

Q: What is an outcome of strong interspecific competition?

A: One species may dominate, outcompete others, or species may evolve to occupy different niches.

Q: How do species coexist despite competition?

A: Through niche differentiation, where species adapt to utilize different resources or habitats.

Survivorship curves : Type 1

organism tend not to die when they are young or middle aged but instead die when elderly.

small numbers of offspring and provide lots of parental care so offspring survive

Ex: Humans, primates, elephant,

most deaths at old age so before that same survivorship and then drastic change from 80 % of life span so 60 left to 90% life span so 30% left ,

although in 10% of life 99 survivors

Survivorship Curve : Type 2

organisms die more and less equally at each age interval.

Relatively have few offspring and provide significant parental care

Roughly equal deaths at all age , equallly going down by slope of -1 from 100 on y axis

Ex: bird , squirrel

Survivorship Curve : Type 3

few organism survive thier younger years . who make it live long lives.

lots of offspring at once like trees releasing thusands of seeds but not providing much care

ex: trees, marine invertibrates, fish , oyster, frog

lower ranges of survivorship on graph

high infant mortality

predict Potential growth of animals, plants, humans

Thomas Malthus: if populations continue to grow at this rate, eventually there wouldn’t be enough resources to provide for everyone.

More true for plants , animals as produce far more offspring than humans can ,

played role in theory of natural selection

reasons for seed count variation

type 3 as fruit have many seeds and few survive young age but some that make it live ling lives.

has lots of offspring like blackberry having 98.5 at once

tomatoes grow vs peaches : seed count variation for reproduction strategy

tomatoes : produce soft berries with single season. any seeds as flowers have multiple ovules so many seeds

Peach: on trees that take years to mature and bear large fuits . Onle have one seed as flower has single ovule and protected inside a hard stone

seeds and mass of fruits

Corn: 353, 245.6

pepper: 25

blackberry: 98.5

tomato : 68

r selected species

high growth rate but low survivebility (“cheap” offspring)

k reelected species

low growth rate but high survivebility (“expensive “ offspring )

r selected characteristics

common in unstable enviorments

many offspring per reproduction event

little parental care

high rate of infant mortality

small body size

short development span(early maturity )

population size is variable (highly fluctuating)

k selected characteristics

stable/predictable enviorments

few offspring per brood

high parental care

low infant mortality

large body

long development span (late onset of muturity)

population size typically stable (reaches carrying capacity)

why difficult to determine k or r

represent 2 ends of extreme in reality

as organisms show intermediate strategy somewhere along spectrum (type 2)

some species may change their selection strategy according to environmental condition

ex: oyster in one extreme 500 million a year , to frog of 200 a yr in middle to chimpanzee on other extreme of 1 every 5 years

species richness

number of unique species that are present , but does not include the number of individuals within those groups

abundance

number of individuals present in each group relative to the total number of indivudius . Abundance calculated by dividing number of individuals by the total number for all groups

equation of relative abundance

of indivuals in group / total # of individuals in all groups *(100)

biodiversity index equation

# of individuals in group/

total # of individuals in all groups

calucltuate the biodiversity index with bean lab

diff types of beans / total # of beans

how bean lab works

species of the taxa and you find its number of Texas or see the differentbrands and fins how many of each are there

then you find the relative abundance after adding all the number of beans, that to be divided to number of beans times 100 to find percentage

biodiversity by total of species of beans divided by total number of beans

which is lowest community

community 3

biodiversity is helpfully cause ?

it is more resilient to changes

how biodiversity indexx used by scientists

health of ecosystem by measuringfg and monitoring it to find normal state

track changes over time with relative abundance

and finsing biodiversity and richness of communities

an area with many speeches would be very rich because of different roles they play in community