College Level Biology Exam #4 - Ecology

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Define the term ecology

ecology is the study of how organisms interact with their biotic and abiotic environments

Define the terms biotic & abiotic

biotic: living things or smth that derives from a living thing

abiotic: things that are physical rather than biological

Give examples of biotic & abiotic factors (i.e., biotic & abiotic factors in the environment)

biotic: humans, poop, mushrooms, plants

abiotic: fire, rocks, air, ice

Define the term population ecology

population ecology is the study of individuals in a population of a single species interacting with their environment, focuses on factors like pop density and pop growth

Define the term population

Individuals of the same species living in the same geographical location at the same time and therefore are able to interbreed

Define population density

the number of individuals of a pop per unit area or unit volume

What is the formula for population density

pop density=n/area

Define the term population distribution

geographical areas occupied by a pop, determined by pop density

What is a species' geographic range

the total sum of the distributions of all the pops of a species

Define the term population dispersion pattern

how individuals of a pop are spaced within their geographic location

What are the three population dispersion patterns. Why does each exist

1. Clumped: cuz of distribution of resources

2. Uniform: cuz of interactions between individuals of a pop

3. Random: uncommon given distribution of resources and interactions with other individuals

List organism(s) that illustrate each of the population dispersion patterns

1. clumped = fish in schools

2. uniform = gannets

3. random = dandelions

What are the main factors that affect population growth & size

births, deaths, aging, migration (emigration and immigration)

Describe the 3 survivorship curves. Explain why a type of organism would have a particular type of curve

1. Type 1: lower early mortality, higher later mortality, cuz of organisms that have better parental care and fewer offspring

2. Type 2: constant mortality rate cuz individuals have an equal chance of dying throughout life

3. Type 3: higher early mortality rate, lower mortality rate for survivors, cuz of organisms that have lower parental care and more offspring

What does the x-axis represent on a survivorship curve? Be specific

x axis is the age or survivorship, acting as the IV

Give examples of organisms that have each of the 3 survivorship curves

1. humans, large mammals

2. rodents, certain lizards

3. trees, fish

What is the difference between exponential growth & logistic growth? Draw a graph of each (label the axes)

exponential growth showcases an ideal environment where there is no limit to resources, while logistic growth is realistic in which there are limited resources and the pop reaches carrying capacity

What can cause a population experiencing exponential growth to shift to logistic growth

when competition rises as resources become limited

Give examples from class to illustrate exponential growth and logistic growth

EG: rabbits in aussie land

LG: paramecia growth in lab, northern fur seals

Define the term carrying capacity. How do you calculate carrying capacity

the max average pop size that can be sustained by limited resources of an environment, to calculate it, it is usually estimated when birth rate=death rate, resulting in 0 pop growth as it has reached carrying capapapacityy

What causes a population to reach carrying capacity

when resources become limited and competition increases, thus causing growth to slow down and death rate=birth rate, preventing the pop from growing indefinitely

How is carrying capacity related to logistic growth

K creates logistic growth, setting the limit for pop growth

What can cause the carrying capacity for a population to change in a given environment

When number of resources increases, causing the K to increase, or vice versa. It can lead to range expansion. It can also change if biotic factors or abiotic affect amount of available resources as well

Can humans affect the carrying capacity of a population

yes, like with raccoons and anna’s humming birds. Humans have increased their resources and thus their K and geographic range

Define the following variables: r, B, D, & K

r=per capita growth rate

B=birth rate

D=death rate

K=carrying capacity

What is the basic equation for population growth?

Nt+1=Nt+B-D

How are B & D related when a population is at K

they are equivalent

Know the details of the population explosion of European rabbits in Australia and explain how it illustrates exponential growth

they grazed on any crop on the land, plus their natural predators in europe were not in aussie land, so nothing slowed down their growth.

How have people tried to control the population growth of rabbits in Australia

by killing them, for over 10 years 2 mill were killed but then the myxoma virus was introduced, causing the pop to drop from 600 mill to 100 mill

Explain how northern fur seals in Alaska illustrate logistic growth. Why did the population experience exponential growth and later reach carrying capacity

After hunting was reduced, the fur seal population grew exponentially because there was plenty of food, space, and little competition. But as the population got bigger, they started to run into limits, such as lack of space, competition, and lack of food. This thus caused them to reach K

How did Gause's experiments with paramecia illustrate logistic growth

As food became limited for the paramecia as their populations started to grow, there was increased intraspecific competition that caused them to hit carrying capacity

What was the effect of the two paramecium species on each other in Gause's experiments

One of them went extinct due to the competition the species would face with the limited food resource. P. aurelia was the better competitor so it grew while P. caudatum went extinct

Define the term life history

the schedule of an organism’s growth, development, reproduction, and survival

What are life history trade-offs

There is always a trade off between reproduction and survival, reproduction always has a cos. Energy put into reproduction cannot be used for growth, repair, etc

What are the life history traits that we covered in class

age @ sexual maturity, frequency of reproduction, # and size of offspring, size @ birth, growth rate, investment in parental care, age-specific survival rate, dispersal behavior

What do the terms semelparity and iteroparity refer to? Give examples of organisms that illustrate each

Semelparity: organisms that reproduce once then die, ex: salmon that lay 1000 eggs then die, using all their energy to reproduce

Iteroparity: organisms that reproduce more than once before death, as they invest in fewer, larger offspring, survival rate of offspring is higher. ex: humans

What are the characteristics of K-selected species? What are some examples of K-selected species

present in stable and predictable environments, pops nearing carrying capacity. They produce fewer offspring, have greater gestation periods, greater parental care

ex: humans, whales, bison

What are the characteristics of r-selected species? What are some examples of r-selected species

present in unstable or unpredictable environments whose offspring have lower chance @ survival, less likely to reach carrying capacity. They produce many offspring, high r, small body size, short time to maturiy, short generation time, little parental care

What are density-dependent factors that regulate population growth

density dependent are effects of factors that depend on pop size

What are the types of density-dependent factors that we covered in class? Be able to define and describe each. Give actual examples to illustrate each

competition, predation and herbivory, disease, etc

What was the effect of smallpox on Native Americans

3 mill NAs were killed result of density dependent factors

What was the reason for the anti-spitting campaigns in the late 1800s–early 1900s

to stop tuberculosis spread, result of density dependent factors

Explain the examples of density-independent factors that affect population growth given in class

effect of factors that do not depend on pop density, like floods, fires, human developments, etc

What is the difference between intraspecific and interspecific interactions

intraspecific is competition within a species, interspecific is between different species

Define the term ecological niche

the full range of environmental conditions (biotic and abiotic) under which a species can exist

Explain the difference between the fundamental niche and the realized niche

fundamental niche is the full range of environmental factors in which a species can exist

realized is the range of environmental factors in which a species can exist when considering limiting factors and what it actually occupies

Define the term community ecology

it is the study of how different species interact in a community and how it affects structure and organization

1. What is an ecological community?

a group of diff species interacting in the same geographical location

What determines a species ecological niche

many factors affect a species ecological niche, but often are all determined by the resources it requires

What is the difference between a habit and a niche

habitat is a physical location a species occupies, while a niche is how it interacts with the location, and its tolerance to environmental factors. Habitat is home, niche is role

Describe Connell’s experiment with barnacles. What did he do in the experiment

he worked with 2 type of barnacles, B on the bottom and C on top, when c was removes, B distribution did not change, and when B was removed C distribution changed

How does Connell’s experiment with barnacles illustrate the fundamental niche and realized niche?

The fact that the C were able to occupy more space than what is usually seen of them is an example of compeition, and how B is always able to outwin C, thus causing a limting factor on C’s niche.

What does it mean that two species’ niches overlap

they share the same sources or environmental conditions, thus leading to competition

Explain the relationship bewteen niche overlap and interspecific competition

niche overlap leads to interspecific competition

Define the term competition

use of a shared and limited resource

What are two possible outcomes of niche overlap

competitive exclusion, when one species goes extinct

resource partitioning, where phenotypic differences evolve making species use diff resources

How do Gause’s experiments with paramecia illustrate niche overlap

both paramecia had be reduced to having overlapping niches, the same limited food resource. This caused competition exclusion cuz of the fact that while they were both competing for the same food, one that gained the upper hand would consistently gain the upperhand and thus cause the other species to go extinct

Give some examples of niche partitioning from class

the warbler species with the feeding zones in the same habitat

What were the species interactions that we discussed in class? Give actual examples of each

Competition (-/-): hyenas and lions competing for prey.

Parasitism, Herbivory, Predation (-/+): lions killing zebra for food, lice on human hair, elephants eating acacia

Mutualism (+/+): bees pollinating plants

Commensalism (0/+): owl nesting in tree

Amensalism (0/-): large mammal trampling grass

Explain the species interactions between ants, acacias, and elephants in Africa

ants and acacia is mutualism

elephants and acacia is herbivory

Why do predator and prey populations often cycle together

cuz they are interconnected, prey is always more than predator but goes down s predators start to eat, predatory pop grows but as prey declines so does predator and this decline in predator allows for prey to rebound, thus creating a continuous cycle

Explain the lynx/snowshoe hare example. How do the population cycles of the lynx relate to those of the hare

when the hare pop goes down so does the lynx, they have the same interconnected cycle

What are the types of defenses that animals & plants use against predation & herbivory (that we discussed in class)

physical like thorns

chemicals like spices, toxins

some animals do mimicry or use plant toxins to defend themselves

What are the types of symbiosis we discussed in class? Give actual examples of each

parasitism: lice in human hair

mutualism: beens and flowers

commensalism: owls in trees

What is a food chain

linear sequence of trophic relationships, less complicated

What is a food web

full web of trophic relationships, describes complexity more accurately

What is a trophic level

position of a species or group of species in the chain or web

Define the following terms: producers, primary consumers, secondary consumers, tertiary consumers, apex consumer

producers: photoautotrophs - photosynthetic organisms

primary consumers: organisms that eat producers

secondary: eat primary

tertiary: eat secondary

apex: top of the chain/web

all are trophic levels frfr

How does energy flow through food webs

nutrients and enrgy pass between trophic levels as 1 organism eats another, only 10% gets transfered, rest is lost as heat

How does the trophic level of an organism relate to what it feeds on and what feeds on it

it dictates what it ears and what eats it, determined by how far it is from the start of the chain