ECOLOGY Flashcards
what is ecology?
the study of the distribution and abundance of living organisms and their interactions with the environment.
ecology is needed to understand evolution.
Give examples of the evolution of a Disease
1: Antibiotics are an effective treatment for bacterial infections because they reduce the population of the bacteria: this is an ecological effect (you will learn about predator prey dynamics and population growth later in this course). 2: Because there is variation in the bacterial population some of them are more resistant to the bacteria than others, and these are the ones that are more likely to survive (ecological effect: interaction between the bacteria and their environment). 3: These antibiotic-resistant bacteria have higher fitness, and therefore reproduce more, which means their population grows faster than the non resistant bacteria.
Define ORGANISMAL
Organismal: How an organism’s structure, physiology and behaviour help them to survive and reproduce
DEFINE POPULATION
Population: A group of individuals of the same species living in an area
DEFINE COMMUNITY
Community: A group of populations of different species living in an area
DEFINE ECOSYSTEM
Ecosystem: The community of organisms in an area and the physical factors with which those organisms interact
DEFINE LANDSCAPE
Landscape: A mosaic of connected ecosystems
DEFINE A BIOSPHERE
Biosphere: The global ecosystem – i.e. the sum of all the planet’s ecosystems and landscapes
These are nested within each other: Global ecology -> landscape ecology -> ecosystem ecology -> community
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Interactions between organisms and the environment (ecology) determines spatial distribution
Both biotic and abiotic factors determine a species’ distribution.
DEFINE BIOTIC FACTORS
Biotic factors are all other living organisms that are part of the individual’s environmentThese include: herbivory, predation, competition, parasitism, mutualism
DEFINE ABIOTIC FACTORS
Abiotic factors are non-living factors (All chemical and physical factors)Temperature: Ectotherm vs Endotherm (Water in cells freezed in cold temp. while protein denature in high temperature)Water: Desert animals & plants (the ability to obtain and conserve water)Salinity: Affect osmoregulation (mangrove can excrete salt)Sunlight: PhotosynthesisRocks & soil:: Affect distribution of plants and thus animals that feed on them
DIFFERENCE BETWEEN macroclimate and microclimate.
Macroclimate determines global patterns and microclimate determines how communities organise themselves at smaller scales
At the scale of the whole globe we have large differences in macroclimate: Sunlight intensity is highest at the equator and lowest at the poles. There is also seasonal variation in how long different parts of the globe experience daylight for.
Solar radiation influences ocean and atmospheric circulation, which then influences precipitation: -There is more rainfall at the equator where there is convection and rising air currents-There is more rainfall on the east of South Africa where we have warm currents than in the west where we have cold currents.
At the scale of the whole globe we have large differences in macroclimate: Sunlight intensity is highest at the equator and lowest at the poles. There is also seasonal variation in how long different parts of the globe experience daylight for.
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IT IS D-O-N-E
difference between rising air and sinking air.
rising air (= convection = rain) vs sinking air (= subsidence = no rainfall)
Microclimate is influenced by landscape features such as topography:
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Mountains can also affect air movement, and therefore rainfall:
explain how this occurs.
The side of the mountain that the air rises on will have more rainfall than the side where the air is sinking. Mountains also affect how hot the environment is at different altitudes, and which side of the mountain is facing the sun (aspect).
Microclimate can also be influenced by other organisms (eg trees alter the way winds move, and the amount of sunlight and rainfall that reaches the ground).
what is a biome?
A biome is a large geographical area of distinctive plant and animal groups, which are adapted to that particular environment. Biomes consist of ecosystems that share similar characteristics, and that are exposed to similar environmental conditions and disturbances.
can an aquatic system have a biome?
YES
Within aquatic systems we also define different biomes. Some of these are in the ocean, and others in freshwater systems on land. Like terrestrial biomes these are affected by ocean circulation, largescale weather patterns, as well as topography (eg the intertidal zone).
HOW MANY BIOMES DO WE RECOGNISE IN SOUTH AFRICA?
In South Africa we recognise 9 terrestrial biomes: Savanna, Grassland, Forest, Desert, Fynbos, Succulent Karroo, Nama-Karroo, Albany Thicket, and Indian Ocean Coastal Belt.
WHY IS IT IMPORTANT TO UNDERSTAND PATTERNS OF population?
Understanding patterns of population increase and decrease is essential as it impacts many other aspects of ecology – including competition and predator-prey dynamics. One practical reason why we need to understand populations is to understand which species are at risk of extinction.
Why would we be interested in population growth?
The patterns of population increase and decrease is essential as it impacts many other aspects of ecology – including competition and predator-prey dynamics. One practical reason why we need to understand populations is to understand which species are at risk of extinction.
A population possess more characteristics the size
Density: number of individuals per unit area
A population possess more characteristics than just the size:
Dispersion: the pattern of spacing among individuals
A population possess more characteristics than just the size:
define demographics
Demographics: vital statistics of populations and how they change over time, mostly concern the addition and reduction of individuals, but also include age/sex structur
difference between population size and density.
Two populations can be of same size but different density. Size affects how viable the population is (as discussed above) but density affects things like the amount of resources each individual is able to get (competition) and disease transmissionLooking at density helps us to understand the size of population an ecosystem can sustain
what is dispersion and what are its 3 types?
Dispersion is the pattern of spacing among individuals; distribution of individualsIt can be clumped, uniform or random. Clumped – this occurs when there is a concentration of resources (like a water hole for elephants) or where organisms live in social groups Uniform – this occurs when there is strong territoriality – eg seabird colonies. Random – plants with seeds blown everywhere.
what is a Life Table?
An age-specific summary of the survival pattern of a population.
Survival is one of the factors that determine POPULATION SIZE<<<>>> there are 3 survivorship curves- namely type I Type II Type III
Describe type I survivorship curve.
Type I: These curves have very low death rates during early & middle life, drops steeper getting to old age
(Large mammals like humans or elephants would be an example. They produce few offspring but have high parental care so these offspring are likely to survive)
describe type II survivorship curve.
Type II: This represents a constant death rate through life (equally likely to die at any time, random)
(rodents, invertebrates, lizards are good examples – they are prey items throughout their lives, and age doesn’t really affect survival)
describe type III survivorship curve.
Type III: These curves show high death rates for young, and then death rates decline if the organisms manage to stay alive
(examples would be organisms that produce lots of offspring but provide no care, e.g. long-lived plants, fishes, marine invertebrates)
There is high variety in reproductive tables: the patterns depend on age at sexual maturity and reproductive strategies. For example, humans and many plants delay reproduction until they are old and established and have acquired the resources they need to survive and reproduce effectively .
On the other hand, trees once they start to reproduce can produce many seeds each year for many years whereas Elephants: produce only one calf in every ~5 years
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DEFINE Life History
A life history is the sequence of events related to survival and reproduction that occurs from birth through death
what are the 3 life history traits that are related to reproduction
Three important life history traits related to reproduction are: the timing of when organisms reproduce (what age, and how often), and how much investment they make in each offspring.
define semelparity
once-off reproduction, a large number of offspring
Define iteroparity
repeated reproduction over the lifespan of the organism
when is Semelparity an appropriate reproductive strategy?
semelparity is an appropriate reproductive strategy:
1: when environments are very variable, and it is not clear how long the adults will live (safer to invest all resources in reproduction and none in growth/survival).
2: when having large numbers of offspring can increase the survival of the offspring by overwhelming the predators (eg Bamboo and some fish species have semelparous reproduction)
When is Iteroparity an appropriate reproductive strategy?
Iteroparity is an appropriate strategy when there are dependable resources & intense competition for resources (eg zebra, elephant, humans)
how do we calculate the Change in population size?
Ultimately, the CHANGE in a population size is the number of BIRTHS plus the number of IMMIGRANTS minus the number of DEATHS minus the number of EMMIGRANTS.
Population change= (birth+immigration)–(deaths+emigration)
WHAT IS A CARRYING CAPACITY. Describe it in terms of (r) and population size.
carrying capacity – the maximum population size a particular environment can sustain.
This means that the value of r is not constant over time, but that it varies depending on resource availability, competition, disease, habitat availability (eg if all the nesting sites are full, then there is nowhere to have your babies).
As r approaches 0 the population approaches its “Carrying Capacity”
ASSUMPTIONS VERSUS REALITY
what are the assumptions made by the logistic and exponential models?
One of the key assumptions made by both the logistic and exponential growth model is that populations respond instantaneously. In reality there are often processes that results in lags/delays in the responsiveness of births and deaths to resource limitation.
The models assume a smooth decline when approaching carrying capacity, with birth rates adjusting to resource availability immediately
Reality: always overshoots when approached K – because animals can use their energy reserve
Population then drops and there is a delay in population growth before the increased offspring are born
There are two tyoes of organisms based in what processes control their demographics.
what are these 2 types?
r- selected
AND
K-selected
The names of these life history strategies comes from K (reached carrying capacity) and r (promote rmax)
What are r-selected species?
r-selected species are species that have very high intrinsic growth rates (high rmax values). These types of organisms are very good at recovering from disturbances, because they can rapidly increase in numbers. However, because of this, they can also rapidly overshoot their carrying capacity, so sometimes show very extreme population crashes also. This leads to much greater fluctuation in population numbers.
What are K-selected species?
In reality organisms are found on a continuum between extreme r-selection and extreme K-selection.
K-selected species are species that are able to persist and compete in situations of limited resources. They have adaptations to survive and reproduce with few resources (competitive ability and efficient use of resources). These tend to result in less rapid population increases (for example, K-selected species will often have fewer offspring, but invest more in the survival of each offspring) – this leads to more stable population fluctuations.
Define Keystone species
A keystone species is a species that has a disproportionately large effect on its environment relative to its abundance.
Playing a critical role in maintaining the structure of an ecological community.
What is a METAPOPULATION?
A metapopulation is a group of populations that are separated by space but consist of the same species.
There can be imigration and emigration between metapopulations
There are different degrees in connectivity, and this can change over time
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