Ch. 1 Introduction: The Web Of Life Flashcards
Amphibians are ___ ___ of environmental problems.
Biological indicators
Amphibian skin is permeable, meaning..
Pollutant molecules can pass through easily
Amphibian eggs have no ___ ___.
Protective shell
Amphibians spend part of their life on land and part in water -
Exposed to pollutants and UV in both environments
Why are amphibians biological indicators of environmental problems?
- skin is permeable
- eggs have no protective shell
- they spend part of their life on land and part in water
Humans have enormous ___ on the planet.
Impact
Ecology -
Scientific study of how organisms affect - and are affected by - other organisms and their environment
Ecology is an ___ approach.
Interdisciplinary
Events in the natural world are ___.
Interconnected
Even species that do not interact directly can be connected by shared ___ ___.
Environmental features
Observations of pacific tree frogs suggested that ___ can cause deformities.
Parasites
Deformities of pacific tree frogs occurred only in ponds which also had an aquatic ___, the intermediate host of the parasite.
Snail
All frogs with deformed limbs had ___ ___.
Ribeiroia cysts
Controlled experiment to test hypothesis that parasites caused deformities:
- tree frog eggs were exposed to parasites in the lab
- four treatments: 0, 16, 32, or 48 parasites
- as parasite load increased, survival decreased and deformities in survivors increased
- supported by other field work
Manipulative field experiment:
- six ponds, three with pesticide contamination
- added tadpoles to cages
- six cages in each pond: three with mesh size allowing parasites to enter, three with mesh blocking parasites
Exclusion cage -
Cage with mesh blocking anything from entering
Manipulative field experiments on pacific tree frogs
What are the treatments?
Pesticides and parasites
Pesticides alone had no effect on deformities, but..
Pesticides significantly weakened resistance to parasites
___ use may also be a factor in frog deformities.
Fertilizer
Fertilizer use may also be a factor:
- fertilizer in runoff to ponds increases algal growth
- snails that harbor parasites eat algae
- greater number of snails result in greater number of parasites
Many human actions have also increased human ___ ___.
Health risks
Damming rivers in Africa increases habitat for snails that carry ___.
Schistosomiasis
What human actions have also increased human health risks?
- Damming rivers in Africa increases habitat for snails that carry schistosomiasis
- new diseases may be related to human activities
- humans expanding into more wilderness areas, contacting more animal hosts increases exposure to “novel” viruses
Birds are primary host and mosquitoes are vectors for what virus that spread from New York City?
West Nile
West Nile
Mammals are ___ carriers.
Dead end
___ is a branch of biology that combines information about organisms and the physical world.
Ecology
Environmental science is even more interdisciplinary
Incorporates concepts from..
- the natural sciences
- the social sciences
- focuses on solutions to environmental problems
Early ecological views:
- a “balance of nature”
- each species has a distinct role to play in maintaining that balance
A “balance of nature” -
Natural systems are stable and tend to return to an original state after disturbance
Tipping points -
Natural systems do not necessarily return to their original state after a disturbance
One view that has stood the gets of time:
- events in nature are interconnected
- a change in one part of an ecological system can alter other parts of that system
Some ecological maxims:
- you can never just do one thing
- everything goes somewhere
- no population can increase in size forever
- there is no free lunch
- evolution matters
- time matters
- space matters
- life would be impossible without species interactions
Ecologists must select appropriate ___ of study.
Scales
Small spatial scales:
Soil microorganisms
Large spatial scales:
Atmospheric pollutants
Short temporal scales:
Leaf response to sunlight
Long temporal scales:
How species change over geologic time
Ecologists study interactions in nature across many levels of ___.
Organization
Ecological studies usually emphasize ___, ___, ___, or ___.
Individuals, populations, communities, or ecosystems
A population -
Group of individuals of a single species that live in a particular area and interact with one another
A community -
Association of populations of different species living in the same area
Organism -
Population -
Community -
Biosphere -
- fish
- school of fish
- coral reef
- all of that together
An ___ is a community of organisms plus the physical environment in which they live.
Ecosystem
___ are areas with substantial differences, typically including multiple ecosystems.
Landscapes
The biosphere:
- all the worlds ecosystems taken together
- all living organisms on Watch plus environments in which they live
Adaptation -
A feature of an organism that improves its ability to survive or reproduce in its environment
Natural selection -
An evolutionary process in which individuals that possess particular characteristics survive or reproduce at a higher rate than other individuals because of those characteristics
Producer -
An organism that uses energy from an external source, such as the sun, to produce its own food without having to eat other organisms or their remains
Consumer -
An organism that obtains its energy by eating other organisms or their remains
Net primary production (NPP) -
The amount of energy (per unit of time) that producers fix by photosynthesis or other means, minus the amount they use in cellular respiration
Nutrient cycle -
The cyclic movement of a nutrient between organisms and the physical environment
All living things evolve ->
Change over time
Three variables important for natural selection to operate:
- variation among individuals within the population
- heritability of the variations
- differential fitness due to variation
Energy enters community when ___ capture energy from an external source and uses that energy to produce food.
Producers
___ moves through ecosystems in a single direction only.
Energy
___ are continuously recycled from the physical environment to organisms and back again.
Nutrients
Ecologists use several methods to answer questions about the natural world:
- observational studies in the field
- controlled experiments in the laboratory
- manipulative experiments in the field
- quantitative models
The study of global climate change involves using a mixture of..
- observational studies
- small-scale experiments
- quantitative models
Climate change -
A directional change in climate that occurs over 30 years or longer
Key aspects of good experimental design:
- replication
- randomization
Replication -
Perform each treatment more than once
As number of replicates increases, it becomes less likely that the results were actually due to a variable that was not measured or controlled
Increased ___ ___ within treatments decreases likelihood that effects are due to chance alone.
Sample size
Randomization -
- assign treatments at random
- helps limit effects of unmeasured variables
Standard ___ ___ are used to determine significant effects.
Statistical analyses
Scientists learn about the natural world by a series of steps called the ___ ___.
Scientific method
Inductive reasoning -
Make observations and ask questions
Deductive reasoning -
Use previous knowledge or intuition to develop a testable hypothesis
Scientific method:
- make observations and ask questions
- use previous knowledge or intuition to develop a testable hypothesis
- make a testable prediction based on hypothesis
- evaluate hypothesis by examining results of experiments, a comparative observational study, or quantitative models
- use results to modify the hypothesis, to pose new questions, or to draw conclusions about the natural world
Alternative hypothesis -
Different “explanations” for phenomenon
Scientific theory -
- from consistent results
- supported by lots of data, usually from many different sources
