Ecology: Concepts and Applications Final Exam Review PDF

11/29/2024 Ecology: Concepts and Applications Final Exam Review B. Skagen ECOLOGY © 2020 McGraw-Hill Education Limited BIO 1172 1...

11/29/2024 Ecology: Concepts and Applications Final Exam Review B. Skagen ECOLOGY © 2020 McGraw-Hill Education Limited BIO 1172 1 Ecology: Concepts and Applications Chapter 10: Species Distribution & Abundance B. Skagen ECOLOGY © 2020 McGraw-Hill Education Limited BIO 1172 2 DISTRIBUTION PATTERNS 3 3 1  11/29/2024 Ecology: Concepts and Applications Distribution Patterns On small scales, individuals within populations are distributed in patterns that may be random, regular, or clumped; on larger scales, individuals within a population are clumped. When you map the distribution of a species, you are highlighting the range of the species. Knowing a species’ range, as defined by presence and absence, is useful, but says nothing about how the individuals that make up the population are distributed in the areas where they are present. © 2020 McGraw-Hill Education Limited 4 4 Ecology: Concepts and Applications Distributions of Individuals Three basic patterns of distribution are observed on small scales: random, regular, or clumped. Random distribution - individuals within a population have an equal chance of living anywhere within an area. Regular distribution - individuals are uniformly spaced. Clumped distribution - individuals have a much higher probability of being found in some areas than in others. © 2020 McGraw-Hill Education Limited 5 5 Ecology: Concepts and Applications Distributions of Individuals (Fig. 10.16) © 2020 McGraw-Hill Education Limited 6 6 2  11/29/2024 Ecology: Concepts and Applications Distributions of Individuals These three basic patterns of distribution are produced by interactions between individuals within a population, by the structure of the physical environment, and by a combination of interactions and environmental structure. Individuals within a population may attract each other, repel each other or ignore each other. 7 © 2020 McGraw-Hill Education Limited 7 Ecology: Concepts and Applications Distributions of Individuals on Small Scales: Clumped Mutual attraction creates clumped, or aggregated, patterns of distribution. Clumped distributions can also occur if individuals produce offspring that fail to disperse far from the parents. 8 © 2020 McGraw-Hill Education Limited 8 Ecology: Concepts and Applications Distributions of Individuals Regular patterns of distribution are produced when individuals avoid each other or claim exclusive use of a patch of landscape. 9 © 2020 McGraw-Hill Education Limited 9 3  11/29/2024 Ecology: Concepts and Applications Distributions of Individuals on Small Scales: Random Neutral responses contribute to random distributions. 10 © 2020 McGraw-Hill Education Limited 10 SPECIES RARITY 11 11 Ecology: Concepts and Applications Commonness and Rarity Commonness and rarity of species are influenced by population size, geographic range, and habitat tolerance. Viewed on a long-term, geological timescale, populations come and go Some populations seem to be more vulnerable to extinction than others, often due to patterns of distribution and abundance. © 2020 McGraw-Hill Education Limited 12 12 4  11/29/2024 Ecology: Concepts and Applications Commonness and Rarity Rare species, even in the absence of human activity, seem to be more vulnerable to extinction. If human activity causes loss of habitat, introduction of new competitors/predators or harvest for economic gain may be particularly at risk. © 2020 McGraw-Hill Education Limited 13 13 Ecology: Concepts and Applications Abundant Species The most abundant species and those least threatened by extinction typically have extensive geographic ranges, broad habitat tolerances, and large local populations at least somewhere within their range. Examples include: starlings, Norway rats, house sparrows, deer mice, marine zooplankton 14 © 2020 McGraw-Hill Education Limited 14 Ecology: Concepts and Applications Habitat Tolerance Habitat tolerance is related to the range of conditions in which a species can live. For example: some plant species can tolerate a broad range of soil texture, pH, and organic matter content, while other plant species are confined to a single soil type. 15 © 2020 McGraw-Hill Education Limited 15 5  11/29/2024 Ecology: Concepts and Applications Rare Species Species that combine small geographic ranges with narrow habitat tolerances and low population densities are the rarest of the rare. Examples include: mountain gorilla, giant panda, California condor. These species are the most vulnerable to extinction. 16 © 2020 McGraw-Hill Education Limited 16 Ecology: Concepts and Applications Chapter 11: Population Structure B. Skagen ECOLOGY © 2020 McGraw-Hill Education Limited BIO 1172 17 Ecology: Concepts and Applications Chapter 11 Learning Objectives 1. Infer the information summarized in a survivorship curve. 2. Use the information from an age distribution to describe the history of survival, reproduction, and potential for future growth of a population. 3. Describe the factors that can change population sex ratios over time. 18 © 2020 McGraw-Hill Education Limited 18 6  11/29/2024 Ecology: Concepts and Applications B. Skagen Introduction Population structure describes the defining patterns within a population, including: Mortality Age distributions Sex ratios Dispersal 19 © 2020 McGraw-Hill Education Limited 19 Ecology: Concepts and Applications Introduction The size and structure of a population is defined by individual survivorship, recruitment, and dispersal Populations grow with birth and immigration Populations fall with death and emigration B. Skagen ∆P = BR – DR + IR - ER 20 © 2020 McGraw-Hill Education Limited 20 Ecology: Concepts and Applications Introduction Analyzing these rates of change is fundamental to demography: the study of factors determining the size and structure of populations through time. A population’s demographic is a key component to its B. Skagen health/ success 21 © 2020 McGraw-Hill Education Limited 21 7  11/29/2024 Ecology: Concepts and Applications Introduction A population’s demographic is characterized by the B. Skagen Age, Sex, and likelihood of survival, as these factors all influence population growth and dispersal per generation. 22 © 2020 McGraw-Hill Education Limited 22 Ecology: Concepts and Applications Patterns of Survival A life table summarizes the pattern of survival in a population. Life table – ecological bookkeeping device used to record the age-specific survival and death, or mortality, rates in a population 23 © 2020 McGraw-Hill Education Limited 23 Ecology: Concepts and Applications Estimating Patterns of Survival Three main methods of estimation: 1. Cohort life table - identify individuals born at same time and keep records from birth (easy to interpret, but often difficult or impossible to collect these data). 2. Static life table - record age at death of many individuals over narrow window in time (requires accurate estimate of age at death). 3. Age distribution - calculate difference in proportion of individuals in each age class (assumes differences in numbers from one age class to next due to mortality and assumes population stable in size). 24 © 2020 McGraw-Hill Education Limited 24 8  11/29/2024 Ecology: Concepts and Applications A life table based on individuals born (or beginning life in some other way) at the same time. Cohort Life Table Very easy to interpret Very difficult to obtain data for 25 © 2020 McGraw-Hill Education Limited 25 Ecology: Concepts and Applications Static Life Table A life table constructed by recording the age at death of a large number of individuals; involves a snapshot of survival within a population during a short interval of time. Easy to interpret Difficult to accurately estimate age at death, depending on species. 26 © 2020 McGraw-Hill Education Limited 26 Ecology: Concepts and Applications Age Distribution The distribution of individuals among age groups in a population; also called age structure. B. Skagen Can use to estimate survival by calculating difference in proportion of individuals in each age class B. Skagen 27 © 2020 McGraw-Hill Education Limited 27 9  11/29/2024 Ecology: Concepts and Applications Dall Sheep: From Life Table to Survivorship Curve (Fig. 11.3) 28 © 2020 McGraw-Hill Education Limited 28 Ecology: Concepts and Applications Patterns of Survival There are 3 general types of survivorship curves: I. Type I – high survivorship of individuals approaching maximum lifespan II. Type II – steady survivorship of individuals with age III. Type III – extremely low survivorship of young, but high survivorship later in life © 2020 McGraw-Hill Education Limited 29 29 Ecology: Concepts and Applications Age Distribution The age distribution of a population reflects history of survival, reproduction, and potential for future growth. It can be used to determine: Periods of successful reproduction Periods of high/low juvenile and adult survival If older individuals in a population will be replaced by younger individuals If a population is in decline. B. Skagen Useful tool in predicting future of a population 30 © 2020 McGraw-Hill Education Limited 30 10  11/29/2024 Ecology: Concepts and Applications E.g. Tree Populations Data initially collect by R. B. Miller to determine relationship between age of white oak and trunk diameter. Able to create age distribution using same data (Fig. 11.11). This is an example of a stable population, as reproduction is sufficient to replace oldest individuals as they die. © 2020 McGraw-Hill Education Limited 31 31 Ecology: Concepts and Applications E.g. Tree Populations Similar data has been collected on Rio Grange cottonwoods (Fig. 11.12). This is an example of a declining population, as the older trees will not be replaced by younger trees. This decline is caused by a reduction in natural, annual seasonal floods which are required for cottonwood seedlings to survive. 32 © 2020 McGraw-Hill Education Limited 32 Ecology: Concepts and Applications Chapter 12: Population Dynamics and Growth B. Skagen ECOLOGY © 2020 McGraw-Hill Education Limited BIO 1172 33 11  11/29/2024 Ecology: Concepts and Applications Chapter 12 Learning Objectives 1. Explain the density dependent and density independent factors that influence population size changes, including birth rates, death rates, immigration, and emigration. 2. Describe the conditions under which populations can grow at geometric or exponential rates 3. Outline the conditions under which logistic growth occurs 34 © 2020 McGraw-Hill Education Limited 34 Ecology: Concepts and Applications Geometric Growth Geometric population growth occurs when a population with pulsed reproduction (non-overlapping generations) grows at a maximum rate (Fig. 12.12). Each successive generations differ in size by a constant ratio: 𝑁 =𝑁 𝜆 35 © 2020 McGraw-Hill Education Limited 35 Ecology: Concepts and Applications Exponential Population Growth Exponential population growth occurs when a population with overlapping generations grow at a maximum rate. The rate of population growth changes in number of individuals with change in time, as the per capita rate of increase times the population size: 𝑑𝑁 = 𝑟𝑁 𝑑𝑡 © 2020 McGraw-Hill Education Limited 36 36 12  11/29/2024 Ecology: Concepts and Applications Logistic Population Growth If resources become limited, population growth rate slows and eventually stops; this is known as logistic population growth. All resources are limited; additionally, species deal with competition, predation, pathogens, and other factors that can act to reduce the rate of population growth. Logistic population growth - exponential growth curve modified to include biotic limitations on population growth. Produces sigmoidal (S-shaped) population growth curve. Carrying capacity (K) is the number of individuals of a population that the environment can support. 37 © 2020 McGraw-Hill Education Limited 37 Ecology: Concepts and Applications Logistic Population Growth Results from Environmental Limitation on Population Size Acting in a Density-dependent Manner (Fig. 12.18) © 2020 McGraw-Hill Education Limited 38 38 Ecology: Concepts and Applications Chapter 13: Competition B. Skagen ECOLOGY © 2020 McGraw-Hill Education Limited BIO 1172 39 13  11/29/2024 Ecology: Concepts and Applications Chapter 13 Learning Objectives 1. Outline the ways in which individuals can compete with other individuals of their own species and of different species. 2. Illustrate evidence from studies that show that resources limitation and competition are widespread. 3. Apply mathematical and laboratory models that provide a theoretical foundation for studying competitive interactions in nature. 4. Discuss how competition has significant effects of species coexistence and the direction of evolution. 40 © 2020 McGraw-Hill Education Limited 40 Ecology: Concepts and Applications Categories of Interactions Categories of interactions among organisms are based on whether interaction is positive, neutral, or negative to each participant. Species interact with each other through a diverse array of ecological interactions. Some are exploitative, others are competitive, and some are beneficial and/or neutral to a species. “-/-” competition - individuals compete for same resources. “+/-” exploitation - one gains from exploiting the other. “+/+” mutualism – both gain from interaction. “+/0” commensalism- one gains while the other is unaffected. 41 © 2020 McGraw-Hill Education Limited 41 Ecology: Concepts and Applications Categories of Interactions (Fig. 13.1) What effect does the interaction with species A have on species B? Positive (+) Neutral (0) Negative (-) Positive (+) Mutualism Commensalism Exploitation (e.g., What effect does predation, parasitism, the interaction herbivory) with species B have Neutral (0) - Neutralism Amensalism on species A? Negative (-) - - Competition © 2020 McGraw-Hill Education Limited 42 42 14  11/29/2024 Ecology: Concepts and Applications Forms of Competition Individuals can compete with others in a number of ways: Intraspecific competition - among members of the same species. Interspecific competition - among members of two species. Resource limitation - limited resources, space, etc. leads to competition B. Skagen 43 © 2020 McGraw-Hill Education Limited 43 Ecology: Concepts and Applications Interference competition involves direct aggressive interaction between individuals. Mechanisms of Competition For example, competition between territorial drakes on a lake for space. 44 © 2020 McGraw-Hill Education Limited 44 Ecology: Concepts and Applications Mechanisms of Competition Exploitative competition involves competition to secure resources first. For example, competition between white pine trees and other forest plants to grow roots to obtain limited amounts of nutrients and water before other individuals (Fig. 13.3). 45 © 2020 McGraw-Hill Education Limited 45 15  11/29/2024 Ecology: Concepts and Applications Self-Thinning: Part 1 Due to intraspecific competition, some plants self-thin. Self-thinning - reduction in population density as a stand of plants increase in biomass, due to intraspecific competition. During self-thinning population density decreases in the absence of outside agents. B. Skagen 46 © 2020 McGraw-Hill Education Limited 46 Ecology: Concepts and Applications Population Growth with Intraspecific Competition versus Interspecific Competition Assume: rmax1 = 0.5, K1 = 200, and N1 = 50 Just intraspecific competition: = 0.5 × 50 = 18.75 Add in interspecific competition, with α12 = 3 and N2 = 25 With interspecific competition: 𝑑𝑁 200 − 50 − 3 × 25 200 − 50 − 75 200 − 125 = 0.5 × 50 = 25 = 25 = 9.375 𝑑𝑡 200 200 200 47 © 2020 McGraw-Hill Education Limited 47 Ecology: Concepts and Applications Competitive Exclusion Principle and Mechanisms of Coexistence The competitive exclusion principle states that two species with identical niches cannot coexist indefinitely. Niche: the role/position of a species within an ecosystem One species will inevitably out-compete the other for resources 48 © 2020 McGraw-Hill Education Limited 48 16  11/29/2024 Ecology: Concepts and Applications Spatial Heterogeneity in the Strength of Competition Factors such as food availability, disease, predation, and climate conditions vary across landscapes. If there is heterogeneity on the landscape in any of these factors, we can then expect species coexistence in some locations, even if they compete strongly elsewhere on the landscape. B. Skagen 49 © 2020 McGraw-Hill Education Limited 49 Ecology: Concepts and Applications Two competing species may fail to approach their carrying Incomplete capacities for a variety of reasons, including predation or Exploitation of disease Resources The effect of this will be to depress N1 and N2, preventing each species from fully using the resources available. 50 © 2020 McGraw-Hill Education Limited 50 Ecology: Concepts and Applications Competitive Equivalence In some situations species may be As a result, coexistence in the landscape completely equal in their competitive should occur. abilities, such that the outcome of competition is not predictable. Although individually one species may win or lose a competitive contest, on average, across a landscape, these species should win and lose an approximately equal number of times. 51 © 2020 McGraw-Hill Education Limited 51 17  11/29/2024 Ecology: Concepts and Applications Variation in Competitive Ability Within a Species Competition coefficient variables are not always fixed for each species There can be individual variation Factors that can influence competitive abilities include: Local environmental conditions Genotypes of individuals competing Age/sex/health 52 © 2020 McGraw-Hill Education Limited 52 Ecology: Concepts and Applications Competition and Niches Partial niche overlap allows for species to coexist: Fundamental niche: the full range of conditions a species can persist in (in theory) Realized niche: the portion of the fundamental niche that a species actually occupies, given limiting factors 53 © 2020 McGraw-Hill Education Limited 53 Ecology: Concepts and Applications Niche Partitioning One way in which species cope with overlapping niches is via niche partitioning Species occupying the same space utilizing the resources differently within that same space Partitioning may be spatial and/or temporal E.g. Nuthatches and creepers; bats and birds; hawks and owls; butterflies and moths; woodpecker species B. Skagen B. Skagen 54 © 2020 McGraw-Hill Education Limited 54 18  11/29/2024 Ecology: Concepts and Applications Chapter 14: Herbivory and Predation B. Skagen ECOLOGY © 2020 McGraw-Hill Education Limited BIO 1172 55 Ecology: Concepts and Applications Chapter 14 Learning Objectives 1. Discuss the diversity of plant defence strategies that have evolved due to herbivory. 2. Illustrate the factors that influence prey populations, including food availability, consumption by predators, and nonconsumptive effects of predators 3. Diagram the population consequences of exploitative relationships. 4. Categorize the different strategies prey populations use to persist in the presence of predators. 56 © 2020 McGraw-Hill Education Limited 56 Ecology: Concepts and Applications Categories of Interactions (Fig. 13.1) What effect does the interaction with species A have on species B? Positive (+) Neutral (0) Negative (-) Positive (+) Mutualism Commensalism Exploitation (e.g., What effect does predation, herbivory, the interaction parasitism) with species B have Neutral (0) - Neutralism Amensalism on species A? Negative (-) - - Competition © 2020 McGraw-Hill Education Limited 57 57 19  11/29/2024 Ecology: Concepts and Applications Herbivory and Plant Defence Herbivory is a widespread ecological interaction and has caused the evolution of a diversity of plant defence strategies. Herbivory generally reduces plant growth and reproduction. In grasses, growth rates often increase after herbivory if nutrients are abundant. B. Skagen 58 © 2020 McGraw-Hill Education Limited 58 Ecology: Concepts and Applications Snow Goose Grazing and a Subarctic Salt Marsh: Part 3 1. Grazing reduced above-ground biomass 2. Grazed plots actually had higher primary productivity than ungrazed plots Overcompensation – increased plant growth following herbivory, compared to growth of plants that did not experience herbivory 59 © 2020 McGraw-Hill Education Limited 59 Ecology: Concepts and Applications Snow Goose Grazing and a Subarctic Salt Marsh: Part 3 Light to moderate grazing of plants can increase productivity due to: 1. Nutrient Cycling: Goose droppings natural fertilizer 2. Reduced Competition: Selective grazing of spp. 3. Disturbance and Regeneration: Stimulate germination/ growth 60 © 2020 McGraw-Hill Education Limited 60 20  11/29/2024 Ecology: Concepts and Applications Plant Defences Plants are subject to natural selection, just like every other living thing. If being eaten reduces the reproductive output and/or survival of an organism, there can be selection for traits that: 1. Make the individual less likely to be eaten (resistance) 2. Reduce the harm associated with being eaten (tolerance) B. Skagen 61 © 2020 McGraw-Hill Education Limited 61 Ecology: Concepts and Applications Morphological Plant Defences Thorns slow down the rate of eating or prevent eating altogether It is more energetically advantageous for herbivores to keep walking and find a less prickly bush than to stop walking and feed slowly. B. Skagen 62 © 2020 McGraw-Hill Education Limited 62 Ecology: Concepts and Applications Morphological Plant Defences In time, herbivores will eventually adapt to a plant’s defences E.g. The split upper lip of pronghorn allows them to consume pincushion cacti: Can carefully grip and manipulate vegetation Strip away spines/barbs before consumption 63 © 2020 McGraw-Hill Education Limited 63 21  11/29/2024 Ecology: Concepts and Applications B. Skagen Chemical defences are common in plants: Toxins - chemicals that kill, impair, or repel Chemical Plant herbivores (e.g. alkaloids). Defences Digestion-reducing substances - inhibit breakdown of plant proteins by digestive enzymes (e.g. tannins). 64 © 2020 McGraw-Hill Education Limited 64 Ecology: Concepts and Applications B. Skagen Plant defenses may be: Chemical Plant Constitutive - produced continuously, regardless of environment. Defences Induced – activated in response to herbivore damage. 65 © 2020 McGraw-Hill Education Limited 65 Ecology: Concepts and Applications Impacts of Predators on Prey Populations Prey populations are affected by: Food/resource availability Consumption by predators Non-consumptive effects of predators 66 © 2020 McGraw-Hill Education Limited 66 22  11/29/2024 Ecology: Concepts and Applications Historical Fluctuations in Lynx and Snowshoe Hare Populations Based on the Number of Pelts Purchased by the Hudson Bay Company (Fig. 14.8) 67 © 2020 McGraw-Hill Education Limited 67 Ecology: Concepts and Applications The Lotka–Volterra Predator–Prey Model Predicts Cycling of Predator and Prey Populations (Fig. 14.13) © 2020 McGraw-Hill Education Limited 68 68 Ecology: Concepts and Applications A Graphical View of the Lotka-Volterra Predator-Prey Model (Fig. 14.14) © 2020 McGraw-Hill Education Limited 69 69 23  11/29/2024 Ecology: Concepts and Applications Predator Avoidance Prey populations can persist in the presence of predators through the use of refugia and a diversity of defence strategies. Mechanisms include: Animal Display (visual & olfactory) Behaviour B. Skagen Refuge use 70 © 2020 McGraw-Hill Education Limited 70 Ecology: Concepts and Applications Animal Display Many prey use visual cues, camouflage, or mimicry to avoid predation. If predator cannot find or recognize prey, it cannot eat it Can be visual, olfactory, or behavioural (e.g. WTDE fawn) 71 © 2020 McGraw-Hill Education Limited 71 Ecology: Concepts and Applications Categories of Animal Display Aposematic colouration: appearance that indicates sp. is toxic or distasteful in some way. Müllerian mimicry - several species of toxic/noxious animals share similar appearance. This can enhance learning by predators, thereby reducing predator risk for mimics. Batesian mimicry – harmless species exhibits features similar to that of harmful species living in same area. 72 © 2020 McGraw-Hill Education Limited 72 24  11/29/2024 Ecology: Concepts and Applications Exploited Organisms and Their Wide Variety of “Refuges”: Space Spatial refuge can be in the form of: Burrows Trees Air Water (if faced with terrestrial predators) Land (if faced with aquatic predators) i.e. microhabitats © 2020 McGraw-Hill Education Limited 73 73 Ecology: Concepts and Applications Prey Density and the Percentage of Prey Consumed Due to Combined Functional and Numerical Responses (Fig. 14.19) © 2020 McGraw-Hill Education Limited 74 74 Ecology: Concepts and Applications Size as Refuge If large individuals are ignored or inconsumable by predators, then large size may offer a form of refuge (Fig. 14.23). However, the maintenance of large bodies is energetically costly. Selection favours behaviours that make prey look physically larger than they are. 75 © 2020 McGraw-Hill Education Limited 75 25  11/29/2024 Ecology: Concepts and Applications Chapter 15: Mutualism, Parasitism, and Disease B. Skagen ECOLOGY © 2020 McGraw-Hill Education Limited BIO 1172 76 Ecology: Concepts and Applications Chapter 15 Learning Objectives 1. Describe how the diversity of parasitic and mutualistic interactions that exist in nature defy generalization. 2. Apply basic ecological principles to the understanding of disease, and the population dynamics of pathogens using compartmental models. 3. Illustrate how interactions can switch from parasitic to mutualistic, depending on the specific conditions of the local environment. 4. Infer when mutualism will evolve. 77 © 2020 McGraw-Hill Education Limited 77 Ecology: Concepts and Applications Categories of Interactions (Fig. 13.1) What effect does the interaction with species A have on species B? Positive (+) Neutral (0) Negative (-) Positive (+) Mutualism Commensalism Exploitation (e.g., What effect does predation, herbivory, the interaction parasitism) with species B have Neutral (0) - Neutralism Amensalism on species A? Negative (-) - - Competition © 2020 McGraw-Hill Education Limited 78 78 26  11/29/2024 Ecology: Concepts and Applications Ecology of Disease Basic ecological principles can be applied to our understanding of disease, and the population dynamics of pathogens can be predicted using a compartmental model. Disease - atypical condition in living organism that cause some sort of physiological impairment. Can be caused by variety of factors, e.g. genetic abnormalities, exposure to toxins, other organisms. Pathogens are parasites that cause disease. Vectors are organisms that transit pathogens without becoming diseased themselves. 79 © 2020 McGraw-Hill Education Limited 79 Ecology: Concepts and Applications Disease Population Dynamics Heritable traits in a pathogen that increase its fitness will tend to increase in frequency, while those that reduce fitness will tend to be selected again. Efficiency of transmission has important implications for population dynamics of host. Transmission may be direct (e.g. contact with infected host) or indirect (e.g. contact with surface that has infection). Horizontal transmission: transfer of disease among individuals of same generation. Vertical transmission: transfer of disease from parent to offspring. 80 © 2020 McGraw-Hill Education Limited 80 Ecology: Concepts and Applications Chapter 16: Community Structure & Functioning B. Skagen ECOLOGY © 2020 McGraw-Hill Education Limited BIO 1172 81 27  11/29/2024 Ecology: Concepts and Applications Chapter 16 Learning Objectives 1. Define species diversity 2. Relate how environmental complexity influences species diversity. 3. Distinguish the relationship between community structure and ecological functions. 4. Summarize how genetic variation within a species influences ecological function. 82 © 2020 McGraw-Hill Education Limited 82 Ecology: Concepts and Applications Introduction Populations of species do not live isolated from each other; they are constantly interacting with one another A Community is a group of interacting species inhabiting some defined area. E.g., Mixed forest 83 © 2020 McGraw-Hill Education Limited 83 Ecology: Concepts and Applications Introduction A mixed forest community differs from a mixed forest ecosystem, which includes abiotic components. Community focuses on the living things and their interactions with one another, such as predation, mutualism, herbivory, parasitism. An ecosystem includes the abiotic environment, such as soil pH, precipitation, nutrient availability, temperature, and the many communities occurring within it. 84 © 2020 McGraw-Hill Education Limited 84 28  11/29/2024 Ecology: Concepts and Applications Introduction Communities contribute to the ecological functioning of ecosystems. Ecological Function- describes the biological, chemical, or physical processes that occur within an ecological system. How an ecosystem functions (and therefore its health) is influenced by community structure. Community Structure- includes attributes such as number of species, relative species abundance, and species diversity. 85 © 2020 McGraw-Hill Education Limited 85 Ecology: Concepts and Applications Species Abundance and Diversity: Part 1 Species diversity is based on two factors: Species Richness - number of species in the community. Species Evenness - relative abundance of species. Can be thought of inverse of dominance. AKA Relative abundance – the proportion of a species within its community (n/N) Species diversity - a combination of the number of species and their relative abundance. 86 © 2020 McGraw-Hill Education Limited 86 Ecology: Concepts and Applications Species Evenness and Species Diversity (Fig. 16.6) © 2020 McGraw-Hill Education Limited 87 87 29  11/29/2024 Ecology: Concepts and Applications Patterns of Species Abundance Relative abundance of species one of most fundamental aspects of community structure. Dominance - one or a few species are substantially more abundant than other species in community. May be measured as biomass, area occupied, number of individuals, etc. There are regularities in the relative abundance of species in communities, regardless of the specific organisms or ecosystem. 88 © 2020 McGraw-Hill Education Limited 88 Ecology: Concepts and Applications Rank-Abundance Curves Plotting the relative abundance of species against their rank in abundance forms the rank-abundance curve, providing information about a community at a glance. AKA. Whittaker Plot A visual way to assess dominance and diversity of a sample by plotting the relative abundance of species by order of dominance (rank). 89 © 2020 McGraw-Hill Education Limited 89 Ecology: Concepts and Applications Rank-Abundance Curves for Two Hypothetical Forests (Fig. 16.8) © 2020 McGraw-Hill Education Limited 90 90 30  11/29/2024 Ecology: Concepts and Applications Describing Diversity It is rare for an ecologist to measure all species found in an area. Sometimes it is easier (and more relevant) to study groups of organisms. Life-form - a body pattern or growth form characterizing a kind of organism. For example: grasses, trees. 91 B. Skagen © 2020 McGraw-Hill Education Limited 91 Ecology: Concepts and Applications Describing Diversity Guild - a group of organisms using B. Skagen B. Skagen resources in a similar way (niche overlap) E.g., Seed eating animals in a montane forest, filter-feeding invertebrates in a stream. 92 © 2020 McGraw-Hill Education Limited B. Skagen B. Skagen 92 Ecology: Concepts and Applications Describing Diversity Functional group - collection of organisms with similar ecological, morphological, physiological, or behavioural features or trophic characteristics. E.g., Diurnal raptors (hawks, eagles) 93 B.McGraw-Hill © 2020 SkagenEducation Limited 93 31  11/29/2024 Ecology: Concepts and Applications Measures of Diversity Alpha diversity - measure of local diversity. Beta diversity - measure of the differences among communities within the region or landscape. Gamma diversity - measure of regional or landscape diversity. B. Skagen © 2020 McGraw-Hill Education Limited 94 94 Ecology: Concepts and Applications Environmental Complexity and Species Diversity Species diversity is higher in complex environments. More complex environments have more available niches (or more niche partitioning) than less complex environments. Why? More life-forms! More niches = More species, guilds, and functional groups © 2020 McGraw-Hill Education Limited 95 95 Ecology: Concepts and Applications Diversity Improves Function Species diversity translates to a more diverse community. B. Skagen A more diverse community will have different ecological functioning from a uniform one. 96 © 2020 McGraw-Hill Education Limited B. Skagen 96 32  11/29/2024 Ecology: Concepts and Applications Chapter 17: Community Interactions B. Skagen ECOLOGY © 2020 McGraw-Hill Education Limited BIO 1172 97 Ecology: Concepts and Applications Chapter 17 Learning Objectives 1. Summarize the feeding relationships in a community with a food web. 2. Explain how strong competitors alter community structure. 3. Outline how the activities of a few keystone species may control the structure of communities. 4. Define how mutualisms can act as keystone species. 5. Recognize that humans can act as keystone species. 98 © 2020 McGraw-Hill Education Limited 98 Ecology: Concepts and Applications Introduction B. Skagen © 2020 McGraw-Hill Education Limited 99 33  11/29/2024 Ecology: Concepts and Applications Ecological Networks Across Trophic Boundaries: Food Webs A food web summarizes the feeding relationships in a community. Food webs incorporate aspects of the biology of the organism and describe the direction of movement of energy and resources within, or even between, communities. Growing recognition that despite only focusing on one interaction (feeding) most published food webs are woefully incomplete. Bias in missing data: over-emphasis on larger organisms and lack of data on detritivores and microbes. 100 © 2020 McGraw-Hill Education Limited 100 Ecology: Concepts and Applications Community Assembly: Competitive Asymmetries Strong competitors can alter community structure. Competitive hierarchy - some species are better competitors than others. Competitive ability can be ranked A>B>C © 2020 McGraw-Hill Education Limited 101 101 Ecology: Concepts and Applications B. Skagen The diversity of animals in a community often varies as a function of the heterogeneity of the plants. Competitive Changes to plant community structure due to Hierarchies competition can cause changes in animal community structure, even if the animals themselves are not competing with each other. 102 © 2020 McGraw-Hill Education Limited 102 34  11/29/2024 Ecology: Concepts and Applications Centrifugal Organization of Species Wisheu & Keddy (1992) proposed this Not all plants are able to perform at theory Based on idea that core and their optimum under all environmental peripheral habitats occur in landscape. conditions. Core area has few abiotic stresses, lots of resources and few pests or Instead, there will exist trade-offs pathogens. between competitive ability and the ability to cope with the different types If species differ in competitive of environmental stresses. abilities, core habitat dominated by best competitor. 103 © 2020 McGraw-Hill Education Limited 103 Ecology: Concepts and Applications Community Assembly: Keystone Species The activities of a few keystone species may control the structure of communities. Keystone species – a species with disproportionate influence on community structure relative to their abundance Keystone species decrease likelihood of competitive exclusion and increase species diversity of community. Can have either a top-down or a bottom-up impact on their communities Influence results in trophic cascade 104 © 2020 McGraw-Hill Education Limited 104 Ecology: Concepts and Applications Ecosystem Engineers Ecosystem Engineer- a species that modifies, creates, or maintains habitats for itself and other species Influence the availability of resources for other organisms Can have significant impact on the physical environment, biodiversity, and ecological processes of an area 105 © 2020 McGraw-Hill Education Limited 105 35  11/29/2024 Ecology: Concepts and Applications Chapter 18: Disturbance, Succession, and Stability B. Skagen ECOLOGY © 2020 McGraw-Hill Education Limited BIO 1172 106 Ecology: Concepts and Applications Chapter 18 Learning Objectives 1. Describe how intermediate levels of disturbance promote higher diversity. 2. Compare the factors that promote community stability, including a lack of disturbance, community resistance, or resilience in the face of disturbance. 3. Illustrate the community changes that occur during succession. 4. Outline the ecosystem changes that occur during succession. 5. Identify the mechanisms that drive ecological succession. 107 © 2020 McGraw-Hill Education Limited 107 Ecology: Concepts and Applications Introduction: Part 1 Succession is the gradual change in plant and animal communities in an area following disturbance. Primary succession occurs on newly exposed geological substrates following any situation where new substrate is exposed or created. Secondary succession follows after a disturbance removes members from an existing community without destroying the soil (e.g. fire). 108 © 2020 McGraw-Hill Education Limited 108 36  11/29/2024 Ecology: Concepts and Applications PRIMARY SUCCESSION Pioneer community - plants that colonize area within first 20 years 109 © 2020 McGraw-Hill Education Limited 109 Ecology: Concepts and Applications Introduction: Part 2 DISTURBANCE Succession occurs indefinitely between disturbance events. This “final” successional community is called the climax community. CLIMAX DISCLIMAX Disclimax communities are those maintained only by constant disturbance (e.g. grazing, drought). REST 110 © 2020 McGraw-Hill Education Limited 110 Ecology: Concepts and Applications The Intermediate Disturbance Hypothesis (Fig. 18.2) © 2020 McGraw-Hill Education Limited 111 111 37  11/29/2024 Ecology: Concepts and Applications Community and Ecosystem Stability Community stability may be due to lack of disturbance or community resistance or resilience in the face of disturbance. Stability - absence of change. May simple reflect lack of disturbance. Biologically uninteresting. Stability may also arise from: Resistance - ability to maintain structure and/or function in face of potential disturbance. Resilience - ability to recover from disturbance. 112 © 2020 McGraw-Hill Education Limited 112 Ecology: Concepts and Applications Visual Representations of Stability Concepts (Fig. 18.5) © 2020 McGraw-Hill Education Limited 113 113 Ecology: Concepts and Applications Biodiversity and Stability Species diversity also can confer increased stability—both through increased resistance and resilience. Biodiversity-stability relationship has become a tenet of ecology. 114 © 2020 McGraw-Hill Education Limited 114 38  11/29/2024 Ecology: Concepts and Applications Post-fire Composition of a Boreal Forest (Fig. 18.12) 115 © 2020 McGraw-Hill Education Limited 115 Ecology: Concepts and Applications Time Scale of Succession Primary succession (Glacial Bay) can required 1,500 years Secondary forest (fire) succession can require 200 years Succession in intertidal communities can take 1.5 years Succession in desert streams can occur on a scale of weeks © 2020 McGraw-Hill Education Limited 116 116 Ecology: Concepts and Applications Ecosystem Changes During Succession Include increases in biomass, primary production, respiration, and nutrient retention. Ecosystem changes during succession include increases in biomass, primary production, Time alone might influence respiration, and nutrient ecosystem through processes retention. such as weathering of bedrock. 117 © 2020 McGraw-Hill Education Limited 117 39  11/29/2024 Ecology: Concepts and Applications Mechanisms of Succession: Part 2 Mechanisms that drive ecological succession include facilitation, tolerance and inhibition. Historically, succession treated as a linear phenomena, with a defined start and end community Unifying concepts for mechanisms of succession provided by Connell and Slayter (1979): 1. Facilitation 2. Tolerance 3. Inhibition 118 © 2020 McGraw-Hill Education Limited 118 Ecology: Concepts and Applications Alternative Successional Mechanisms (Fig. 18.25) © 2020 McGraw-Hill Education Limited 119 119 Ecology: Concepts and Applications Facilitation The facilitation model proposed that many species attempt to colonize newly available space but only species with particular characteristics can establish. Species capable of colonizing new sites are pioneer species. Pioneer species modify environment so that it becomes less suitable for them but more suitable for species found in later successional stages. Replacement of early successional stages until resident species no longer facilitate colonization by other species. 120 © 2020 McGraw-Hill Education Limited 120 40  11/29/2024 Ecology: Concepts and Applications Tolerance The tolerance model proposed that the initial stages of colonization not limited to few pioneer species. Juveniles of species dominant at climax can establish in earliest successional stages. Species colonizing early in succession do not facilitate colonization by other species. Climax community established when no more species tolerant of environmental conditions to colonize. 121 © 2020 McGraw-Hill Education Limited 121 Ecology: Concepts and Applications Inhibition The inhibition model proposed that any species can colonize area during early stages of succession. Early occupants modify environment to make area less suitable for any species. Early colonizers inhibit colonization by later arrivals. Climax community long-lived species resistant to damage by physical or biological factors. 122 © 2020 McGraw-Hill Education Limited 122 Ecology: Concepts and Applications Chapter 21: Landscape Ecology B. Skagen ECOLOGY © 2020 McGraw-Hill Education Limited BIO 1172 166 41  11/29/2024 Ecology: Concepts and Applications Chapter 21 Learning Objectives 1. Describe the processes and factors that create and change landscapes. 2. Categorize the factors that determine landscape structure. 3. Identify the ecological processes that landscape structure influences. 167 © 2020 McGraw-Hill Education Limited 167 Ecology: Concepts and Applications Introduction A Landscape is a heterogeneous area composed of distinct patches. Landscape Elements - distinct patches within landscape. Landscape Ecology - study of relationship between spatial pattern and ecological processes over a range of scales. © 2020 McGraw-Hill Education Limited B. Skagen 168 168 Ecology: Concepts and Applications Origin of Landscapes Landscapes heterogeneity occurs because: 1. Each patch (community) reflects particular environmental conditions 2. Communities occur at various stages of succession 3. Communities are altered by land use 169 © 2020 McGraw-Hill Education Limited 169 42  11/29/2024 Ecology: Concepts and Applications Origins of Landscapes Landscapes are created and change Geological processes such as in response to geological volcanism, and sedimentation source of many landscape elements. processes, climate, activities of organisms, and disturbance events. Climate, fire and activity of organisms can also influence landscape structure, e.g. beavers, as ecosystem engineers, create new elements (pond, riparian habitat) in local landscape. 170 © 2020 McGraw-Hill Education Limited 170 Ecology: Concepts and Applications Landscape creation occurs via 2 types of processes: Origins of Endogenic - forces originating from within the earth i.e. Plate tectonics, volcanism Landscapes Exogenic – Forces originating from external sources i.e. Weathering, glaciation, erosion & deposition, ecosystem engineers 171 © 2020 McGraw-Hill Education Limited 171 Ecology: Concepts and Applications Landscape Structure Landscape structure includes the size, shape, composition, number, and position of patches, or landscape elements, in a landscape. Patch - relatively homogeneous area that differs from surroundings. Matrix - element within the landscape that is most spatially continuous. Corridor - strip of habitat connecting similar habitat types patches across a landscape. Patches within landscape form a mosaic that we call landscape structure. 172 © 2020 McGraw-Hill Education Limited 172 43  11/29/2024 Ecology: Concepts and Applications Landscape Structure © 2020 McGraw-Hill Education Limited 173 Ecology: Concepts and Applications Landscape Processes Landscape structure influences processes such as the flow of energy, materials, and species distributions across a landscape. These processes include: Movement of organisms Distribution of species on landscape Local population density and extinction risk Nutrient cycling, lake and river chemistry 174 © 2020 McGraw-Hill Education Limited 174 Ecology: Concepts and Applications Landscape Structure and the Movement of Animals: Part 1 Landscape structure can influence movement of organisms between potentially suitable habitats. Habitat fragmentation - division of previously intact habitat into several isolated patches. Habitat connectivity – degree of interconnectedness between patches, allowing for unimpeded movement of organisms. Diffendorfer, Gaines, and Holt (1995) studied how patch size affects movement of three small mammal species (cotton rats, prairie voles, deer mice). 176 © 2020 McGraw-Hill Education Limited 176 44  11/29/2024 Ecology: Concepts and Applications 177 © 2020 McGraw-Hill Education Limited 177 Ecology: Concepts and Applications Edge Effects and Fragmentation Edge Effects – changes in population or community struct