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Ultra Summary.docx

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Jurek Kolasa

Ultra Summary: Bio 3DD3  Ecological System: Community or Ecosystem  Ecological System (Community or Ecosystem) are made up of fragments of local populations of species, where the same taxonomic species may exist elsewhere. Thus, we can’t just define community based on the number of species unless we look at large scale: ‘Scale’ changes things  Membership of a species in a community ranges from almost permanent to almost accidental  Habitat is hard to define because it changes depending on the perception of the individual spices (organism), and it usually forms a multi-dimensional hierarchy. It is ‘dynamic’.  Community will have species 1) That are entirely living on it (usually in-case of large-scale/extent) 2) Present in portion of that area 3) Present because they are also present in surrounding environments (some birds for example) 4) Present due to similarities of other far-away communities (Ecological timeline)- Very similar to their actual timeline  Due to this interactions between species (as seen by three species on an island image) are asymmetrical: One species (a) may interact with species (b) completely, but b can interact with various other communities, so it is mostly free of pressure and completion from a, whereas a is fully covered by B: In a given community one population might have an advantage over the other  In a given community, the more abundant species will occupy a smaller range of space and the less abundant species will occupy a large area of space (in comparison) because species that are restricted to small areas (can’t migrate) can specialize and increase abundance whereas the non-restricted ones do not need to (based on abundance (y) vs. space (x) graph)  Local community has species in which the habitat is important, optional or occasional  Species can be permanent or transient (visitor)  The ecological representation of a species (in terms of numbers) change (i.e. an ant in a local community vs. deer- there would be more ants for sure)  Species from a ‘community’ might show various integration from its sister communities (or its own broader population)  How distinct/unique they are locally depends on if they are permanent or migratory (i.e. ones that are not able to migrate might depend more on local reproduction, than migratory birds who can just reproduced in a different population if conditions are right)  Level Integration of a species determine how important that community is to that species/ population of the species. For example migratory birds will be more flexible and less damaged when the community is damaged, because they are less integrated in the community  Transients: General term for anything that does not depend on its local community (Wild-beast travels for grass). Linked mostly to the outside population, might have come by in accident, might not stay and reproduce in the future (accidental dispersal). May CAUSE a significant impact on the local community, but they do not depend on it  Graph that shows colonization and extinction of bird species, the species with no extinction are very dependent on the community, whereas the ones that show extinction (not part of the community) are migratory (transient)  Broadly Ranging Species: Another term, a species that has a broad extent (certain birds) and can occur in various local populations (transients fall into this)-the dynamics of these species are best understood in a large scale  Balance between various classes of members (permanent-optional) may change depending on various factors (succession, community development, its stage etc.)  Same taxonomic species may change characteristics depending on environment (protest examples and how they switch their trophy) : populations of the same species may have different characteristics  Species differ in ‘traits’: form gradients (examples below): 1) Reproductive gradient: Species that differ in how many organisms they have 2) Gradient of Resource Utilization: Species differing in resources 3) Gradient of Habitat Specialization 4) Example of butterflies specializing to each genera of flower  Niche: Ecological characteristics of a species. Set of biotic and abiotic conditions a species can live under, usually viewed in 1-3 dimensions based on number of factors (biotic or abiotic like temperature or ph.)  In two dimensions we compare two variables (pH and temperature) and it is like a box (simple to view)  Fundamental niche: Areas where a certain can live under (due to the right factors), and realised niche (portion of the fundamental niche that is actually occupied by the species) because they are limited by other factors like competition  Relationships between species niche and it’s habitat: 1) Grenalian Niche: Species present in suitable habitat 2) Hutchinsonian: Species present mostly in suitable habitat, but some of the species are excluded from the suitable habitat due to biotic interactions 3) Source-Sink Dynamics: Species exist outside their source (suitable habitat) in some numbers 4) Dispersal Dynamics: Some species do not occur in the suitable area (on random) due to dispersal, kind of like hutchinsonian but hutchinsonian has a whole new oval that blocks out species presence.  Niche can overlap in various ways, when they overlap things like competition, symbiotic relationship might take place. The more they overlap the stronger these relationships are or competition is. Below are the scenarios in a species can overlap: 1) Co-existence: Both species have the same niche, same resource gradient (strong relationships and interactions) 2) Included: One species occur in greater numbers, but fall within the range of another, more damage done to this species because the other species has a bigger resource gradient, and can go there when completion occurs 3) Reciprocal: Occur in similar numbers, but an equal portion of them interact 4) Asymmetric: One species has more space than the other, less pressure on that species 5) Non overlaps: Abutting: Connected, but not overlapped, and Disjunction: completely no overlaps  Tolerance: How tolerant a species is to the community factors, but unlike niche it is inherent, has to do with genetics, and physiology (does not depend on habitat or location). One dimension response curve (an ideal curve is bell shaped or Gaussian curve. For example a graph showing tolerance in temperature, will measure how species will perform in temperature (varying). In most cases, best performance in the middle, and poor in both extremes. It is based on standard deviation or how spread out the stuff are  Ecological Range: Species not present not because it cannot tolerate (opposite), but this Is more about chance and how a particular species perform in a given community- how well organisms perform by chance, mating, due to dispersal etc. (a same species can tolerate rock pools with similar conditions, but due to chance, and performance a species might be present in one rock pool but not the other (even though they can tolerate both)  Habitat: Definition depends on the species, is multidimensional (various factors competition, available resources) could limit and change perspective of what ‘habitat’ is based on a species (examples plants that specialized due to herbivore)  Habitat Structure: Resolution increases as we get closer down the hierarchy. As scale increases, resolution decreases  Multidimensional Volume: We can use infinite variables to define a habitat + Hierarchy (changing based on scale) =Habitat  Algae and mushroom (Lichen: at finer resolutions we can distinguish individual habitats and own set of characteristics  Spatial configuration of patches of habitats: Can be Fragmented (isolated fragments of similar habitats), Embedded (one habitat embedded in patches within another), or Continuous and Compact (a habitat that flows together- one large habitat with no disruption). Regardless in which way they are subdivided, the general multidimensional model applies similarly to all (all have finer habitats within general habitats)  Is the depiction of hypothetical species’ habitats true for one location or the whole range where species occurs? No it changes in space because conditions change in space  Narrow range species (down the hierarchy) are habitat specialists  Broad range species (up the hierarchy) are habitat generalists  Intermediate range species: In the middle, medium resolution  Highest resolution on bottom-- increases towards top  Ecologists now consider wider scales  Community’s species are really more or less isolated populations, with unequal contributions to the life of community and unequal needs and sensitivities  Habitat is a multidimensional set of factors affecting species  Habitat is hierarchical and can conveniently be mapped  Habitat hierarchy emerges when investigator (or a species) uses different resolution of detail (changes scale)  Scale change is also important in research. This is because:  Processes and patterns change depending on our scale  Spatial and temporal scales are positively related, with large entities exhibiting slow dynamics; and small entities changing fast  This has implications for interactions Chapter 2: How is Scientific Method Used in Community and Ecosystem Ecology?  To answer many questions in Ecology related to Ecological systems you must develop and test a hypothesis  Hypothesis is based on ecological theories , and scientifically accepted facts  Testing of hypothesis: Experiments + Comparative studies (Both depend on using Statistical methods)  Mostly studied in small spatial and temporal scales (why easier to accesses because it is a smaller area, and faster time is better because we want results fast)  Then, using special methodologies, we can take the ‘small scale’ studies and apply it to general ‘larger scales’ (most of these methods are in early stages of development)  The first step is Scientific Theory : Primary guide in which hypothesis, methods etc. are derived from: Logical web of well-founded assumptions, observations, and expectations  Ecology does not have a unifying (common theory), but number of theories (assumptions, observations or expectations) can be used to generate hypothesis  Hypothesis: If testable usually has the ‘if’ and ‘then’ (it specifies conditions and ‘predicts’ the consequences’: If salt dissolves (condition), then it will dissolve in water (consequence)  The consequence (prediction) MUST BE UNIQUE: Only when predictions are unique, we can distinguish them from other patterns etc.  Null hypothesis: Explains the outcome in-case hypothesis (if-then) is NOT true (Usually saying if ‘consequence’ is not true, then the cause is not present: If salt does not dissolve in water, then salt is not soluble in water  SCALE: Is an important risk factor, when testing hypothesis, we need to address and specify the scale of study!  Hypothesis Testing: Numerous steps ranging from data collection all the way to statically analysis , particularly ECOLOGY RELIES ON STATISTICAL METHODS  Statistical testing is best suited to extract responses of interest from inherent internal and external sources of variability as well as various systematic but uncontrolled factors.  Ecologists can use models, observations, experiments  Ecologists MUST specify the scale of study  Example (recall species diversity decreasing with latitude- go back and check book if needed): Average niche breadth increases with increasing habitat variability northwards (increase niche breadth= more overlap of niche= greater competition = reduction of species)  This REDUCTION OF SPECIES was due to COMPETTITIVE EXLCUSION (Niche Theory Premise)  Even if our new hypothesis, requires logic from old ones (like we already know that species drop as we go north), we still need to prove all the hypothesis sets and formulate ours (we can’t just use other ‘known’ hypothesis just because they are general)  Steven supported the old concepts by showing data of mammals that show a steady increase in geological range depending on degrees of latitude (this explains why niche breadth increases northwards), and now we can actually formulate the own hypothesis and test it  Example 2: Rock pool model system: Each rock pool is a small ecosystem (contains community of invertebrates +others). They were testing the hypothesis that ‘decrease in species variability’ is due to ‘competition’ (not the same as last one where they were saying before)  Four main factors measure (Oxygen, Temperature, PH, and Salinity) in 49 rock pools over the years: Length of bar= 2 standard deviation around mean, the longer the bars are the more variable they are. Short bars are less variable  We have multiple variables (different ones) we need a way to put all the variables together into one SYNTHETIC VARIABLE (overall variable) (so we can get a clear picture of the overall variability of the environment) requires the use of statistics  Synthesis Variables are made use PCA (Factor or Principal Component Analysis): This processes looks for similarities (correlations) among variables, and group the similar variables into sub-groups: Thus correlated variables may be grouped into PCA1 and PCA2 for example.  They used PCA groups to check variance in the entire pool system and PCA 1 actually showed the most variance (not PCA 2- so these group of correlated variables did not have much effect): Used to determine species ecological niche (a species occurring in similar PCA 1 values all over has a narrow niche, but the one that occurs in varying PCA 1 values has a broad niche- able to cope with varying things better)  After gathering the PCA values  Standard deviation (STATISTICS) was used to determine relationships  So we know that only broad-range species can exist in variable environments, but we still need to determine if variability actually causes a reduction in niche  This can be accomplished by plotting species richness vs. habitat variability  The graph shows that habitats variability increases lead to drop in richness (loss of niche)  We need to make sure the result is SIGNIFICANT!  We still need more evidence to show that competition affects continent-scale gradient of species diversity (scale is bigger now from rock pool to continent, and also we need to show evidence of competition, so far we just showed that variables cause decrease in richness)  Third step: Check weather habitat variability increase when broader niche species are present (we know that broader niche species can survive in variable habitats) mean ecological range of all species in pool vs. habitat variability  as range increases variability increases: More variable habits are home to broader niches (result from this graph)  This small scale TREND corresponds with the large scale trend, but this does not necessarily show COMPETITION!  Thus, we can conclude that the gradient is not produced by broad range species outcompeting other species from locations they occur. Rather, it is differential extinction of narrow range species from variable pools that creates the gradient.  Steps and connections involved in the formulation and partial solution to a scientific problem posed by the example. The problem was a question motivated by observation. It necessitated a tentative answer – the hypothesis. The hypothesis allowed formulating a testable prediction which was contrasted against the null hypothesis. The answer may lead to further questions or problems for the cycle to be repeated with new contents.  Two types of hypothesis: 1) Qualitative: Really good when s. methods are not available, but even s. methods are used to test a qualitative hypothesis (although it is not meant to be used). Example variable habitats= home to broader niche species (is qualitative , but we used stats to test it)
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