Lecture 10 - Ecology Study Guide PDF

Understanding life history strategies and the trade-offs associated with reproduction is crucial for comprehending how different species allocate resources to growth, reproduction, and survival. Here's an overview of the key concepts: 1.Life History: 1. Life history refers to the suite of traits and...

Understanding life history strategies and the trade-offs associated with reproduction is crucial for comprehending how different species allocate resources to growth, reproduction, and survival. Here's an overview of the key concepts: 1.Life History: 1. Life history refers to the suite of traits and strategies that organisms employ to maximize their reproductive success in their specific environments. 2. Life history traits include age at first reproduction, number and size of offspring, reproductive lifespan, and investment in parental care. 2.Trade-offs Associated with Reproduction: 1. Trade-offs arise when resources allocated to one life history trait cannot be used for another. For example, energy invested in reproduction may come at the expense of growth, survival, or future reproduction. 2. Trade-offs may occur within an individual's lifetime or between different life stages. 3.Cost of Reproduction: 1. The cost of reproduction refers to the negative effects that reproduction imposes on an organism's survival and future reproductive success. 2. These costs can include increased mortality risk, reduced immune 1 function, decreased growth or body condition, and shortened lifespan. 4. Resulting Life History Traits (r vs K Selection): 1. Life history traits can be categorized along a continuum between two contrasting strategies: r-selection and K-selection. 2. r-selection: 1. r-selected species prioritize rapid reproduction and high population growth rates in unpredictable or unstable environments. 2. Traits associated with r-selection include early maturity, high fecundity, small offspring size, little parental care, and short lifespan. 3. K-selection: 1. K-selected species prioritize competitive ability and long-term survival in stable or predictable environments. 2. Traits associated with K-selection include delayed maturity, low fecundity, large offspring size, extensive parental care, and long lifespan. Understanding these life history strategies and the associated trade-offs helps ecologists predict how populations will respond to environmental changes, habitat alterations, and anthropogenic disturbances. It also provides insights into the evolution and adaptation of species to their ecological niches. Let me know if you need more information on any of these topics! 1 It sounds like you're describing a scenario where reproductive individuals, particularly those involved in milk production, experience higher mortality rates compared to non-reproductive individuals. This phenomenon can result from various factors related to the physiological demands of reproduction and milk production, as well as potential trade-offs between reproductive effort and survival. Additionally, the term "yield" likely refers to the production capacity of an individual, such as milk yield in dairy cows, which can be influenced by reproductive status and health. Here are some key points to consider: 1.Physiological Demands of Reproduction: 1. Reproduction and lactation impose significant physiological demands on individuals, including increased energy expenditure, metabolic stress, and susceptibility to health issues. 2. Reproductive females, particularly those producing milk, may experience greater physiological strain, which can weaken their immune system and make them more vulnerable to diseases and health complications. 2.Trade-offs Between Reproduction and Survival: 1. In many species, there are trade-offs between investing resources in reproduction and allocating them towards somatic maintenance and survival. 2 2. Individuals that allocate more resources towards reproduction, such as milk production, may divert resources away from immune function, tissue repair, and other mechanisms that contribute to survival and longevity. 1.Stress and Health Issues: 1. Reproductive individuals, especially those undergoing lactation, may experience stress-related health issues such as metabolic disorders, nutritional deficiencies, and reproductive diseases. 2. High levels of stress hormones, such as cortisol, associated with reproduction and lactation can suppress immune function and increase susceptibility to infections and diseases. 2.Yield and Reproductive Status: 1. Yield, in the context of dairy cows, typically refers to the amount of milk produced by an individual over a certain period. 2. Reproductive status, including pregnancy and lactation, can influence milk yield in dairy cows. Pregnant and lactating cows typically have higher milk production compared to non-pregnant, non-lactating cows. 3. However, the physiological demands of reproduction and lactation can also impact the health and longevity of dairy cows, potentially affecting their overall productivity and yield over time. Overall, the relationship between reproduction, milk production, and mortality rates in livestock populations is complex and influenced by various factors related to physiology, health, and environmental conditions. Understanding these dynamics is important for optimizing animal welfare, productivity, and sustainability in agricultural systems. 2 Absolutely, you've highlighted a classic trade-off in life history strategies seen across various species: the allocation of resources between growth and reproduction. Here's a breakdown of how this trade-off works: 1.Investment in Growth: 1. Allocating resources to growth means prioritizing the development and maintenance of the individual's own body size, strength, and physiological functions. 2. Individuals that invest heavily in growth may delay reproductive maturity as they allocate resources to building a larger body size and acquiring necessary resources for future reproduction. 3. Higher investment in growth typically results in larger body size, which can confer advantages such as increased competitiveness for resources, improved survival, and enhanced reproductive success later in life. 2.Fewer Offspring: 1. Investing more resources in growth often means allocating fewer resources to reproduction, resulting in a reduced reproductive output in terms of the number of offspring produced. 2. Individuals that prioritize growth may delay reproduction until they reach a larger size or until environmental conditions are more favorable for 3 successful reproduction. 3. However, while they may produce fewer offspring overall, these individuals may invest more heavily in each offspring, providing better parental care and increasing the survival chances of their offspring. 1.Investment in Reproduction: 1. Allocating resources to reproduction means prioritizing the production and care of offspring, including the energy and resources required for gestation, lactation, and parental care. 2. Individuals that invest heavily in reproduction may prioritize early reproductive maturity and produce a larger number of offspring over their lifetime. 3. Higher investment in reproduction typically results in earlier reproductive maturity, shorter interbirth intervals, and higher fecundity, but may come at the expense of slower growth and reduced survival of the parent. 2.Lower Parental Growth: 1. Individuals that allocate more resources to reproduction may experience slower growth rates or smaller adult body sizes compared to individuals that prioritize growth. 2. Reproductive investment can divert energy away from somatic growth and maintenance towards reproductive activities, resulting in slower overall growth and development of the parent. 3. While these individuals may achieve reproductive maturity earlier and produce more offspring, they may have reduced competitive ability or lower survival rates compared to individuals that prioritize growth. Overall, the trade-off between growth and reproduction represents a key aspect of life history strategies and reflects the allocation of limited resources towards different fitness-enhancing activities. The optimal balance between growth and reproduction varies depending on environmental conditions, life history traits, and ecological constraints, and can influence individual fitness and population dynamics in diverse ways. - Example a fish- when making less eggs more growth more eggs less growth 3 The trade-off between seed production and seed size is a fundamental aspect of plant reproductive strategy and has important implications for plant fitness and population dynamics. Here's an overview of this trade-off: 1.Seed Production: 1. Seed production refers to the number of seeds produced by a plant during its reproductive phase. 2. Plants invest resources, such as energy and nutrients, into producing seeds as a means of dispersing their offspring and ensuring the next generation's survival. 3. Higher seed production generally increases the likelihood of successful reproduction by providing more opportunities for seed dispersal and germination. 2.Seed Size: 1. Seed size refers to the physical dimensions and mass of individual seeds produced by a plant. 2. Larger seeds typically contain more energy and nutrients, which can provide a competitive advantage to seedlings during germination and early growth stages. 3. Larger seeds may have higher survival rates, faster growth rates, and 4 increased resistance to environmental stresses compared to smaller seeds. 3. Trade-off: 1. The trade-off between seed production and seed size arises because plants have limited resources to allocate to reproduction. 2. Plants must allocate resources between producing a larger number of smaller seeds or a smaller number of larger seeds. 3. Allocating resources to seed production may result in a larger number of smaller seeds, while allocating resources to seed size may result in a smaller number of larger seeds. 4. Plants must strike a balance between these two strategies to optimize their reproductive success and fitness in their specific ecological context. 4.Ecological Implications: 1. The trade-off between seed production and seed size can have significant ecological implications for plant populations and communities. 2. Environmental factors, such as soil fertility, moisture availability, and competition, can influence the optimal allocation strategy for plants. 3. In resource-limited environments, plants may prioritize seed production over seed size to maximize the number of offspring produced. 4. In more favorable environments with fewer constraints on resources, plants may invest more heavily in producing larger seeds with enhanced competitive ability and survivorship. Overall, the trade-off between seed production and seed size reflects the complex interplay of ecological, physiological, and evolutionary factors shaping plant reproductive strategies. Understanding this trade-off is essential for predicting plant population dynamics, community structure, and ecosystem functioning in diverse habitats and environmental conditions. 4 1.sexual Reproduction Advantages: 1. Rapid Population Growth: Asexual reproduction can lead to exponential population growth, as each individual can produce numerous genetically identical offspring without the need for mating. 2. Energy Efficiency: Asexual reproduction avoids the energy costs associated with producing males, mating behaviors, and courtship rituals. All energy can be directed towards reproduction, leading to more efficient resource utilization. 2.Sexual Reproduction Advantages: 1. Genetic Diversity: Sexual reproduction generates genetic diversity through genetic recombination, which can enhance population resilience to environmental changes and increase the potential for adaptation and evolution. 2. Purging of Deleterious Mutations: Sexual reproduction allows for the elimination of harmful mutations through genetic recombination and the production of offspring with novel genetic combinations. 3. Reducing Competition: Sexual reproduction can reduce intraspecific competition by producing offspring with varying traits, dispersal abilities, and ecological niches, thereby reducing competition for resources among 5 offspring. In summary, while asexual reproduction can result in faster population growth due to the absence of mating costs and production of genetically identical offspring, sexual reproduction offers advantages such as genetic diversity, adaptation, and resilience to changing environments. The trade-off between these strategies depends on the ecological context, including factors such as environmental stability, resource availability, and reproductive strategies of competing species. 5 Yest cells- axsecually reproduction and will split and make copies of themesevles Can switch to sexually reproduction - Is the environment good 6 Predicting the future of populations involves analyzing data on various population parameters and using mathematical models to forecast population dynamics. Here's how we can "tell the future" of populations using data: 1.Life History Tracking of Births and Deaths: 1. By tracking the births and deaths of individuals within a population over time, we can construct a life table that summarizes the survival and reproductive rates of different age cohorts. 2. Life history tracking allows us to understand age-specific mortality rates, age at first reproduction, reproductive lifespan, and other vital statistics that influence population growth. 3. With this data, we can project future population sizes by extrapolating the survival and reproductive rates of different age classes into the future. 2.Tracking Fecundity by Age: 1. Fecundity refers to the reproductive capacity of individuals, typically measured as the number of offspring produced per female. 2. By tracking fecundity by age, especially for females, we can understand how reproductive output varies across different age classes. 3. Examining age-specific fecundity rates allows us to identify patterns such 7 as reproductive senescence (reduced fertility with age) or reproductive skew (variation in reproductive output among individuals). 4. Predicting future population trends requires incorporating age-specific fecundity rates into population models to estimate future reproductive output and population growth rates. 1.Population Projections into the Future: 1. Population projections involve using mathematical models to forecast population dynamics based on current demographic data and assumptions about future trends. 2. Population projection models may include parameters such as birth rates, death rates, immigration, emigration, and age-specific reproductive rates. 3. Commonly used population projection models include Leslie matrices, age-structured population models, and demographic stochastic models. 4. By inputting current demographic data and assumptions about future demographic trends (e.g., changes in fertility rates, mortality rates, immigration), these models can generate projections of future population sizes, age structures, and growth rates. Overall, predicting the future of populations relies on robust data collection, including demographic information on births, deaths, and reproductive output. By analyzing this data and applying appropriate mathematical models, researchers can generate population projections that inform conservation efforts, resource management strategies, and policy decisions. 7 To calculate the number of individuals in the cohort that survived to age 3, we need to find the number of individuals (nx) alive at age 3 (x=3) in the life table. Given the following data: x = age: 0, 1, 2, 3, 4, 5 nx = number in cohort alive at age x: 530, 159, 80, 48, 21, 5 We find that the number of individuals alive at age 3 (nx at x=3) is 48. Therefore, the number of individuals in the cohort that survived to age 3 is 48. A= n3= 48 indiviudals are still alive 8 A13 BABIES PER FEMALE OF X=2 A2ADD UP ALL THR BX UNTIL YEAR 5 0+2+3+3+2+0=10 BABIES IS SHE LIVES TO 5 Q3HIGHEST survial right is at o.60 look at sx which is survial rate 9 Q4The lowest survial rate but not looking at 5 because they assume it will die out so age 4 the survival rate is 0.25 9 Think 50/50 10 female assume 10 male just not tracking them Answer- 10 Nx- is the year Bx- is the number of offspring 11 12 10 will be mul;tple of 2.0 of that year 13 0= 20 times 0.30 gives us 6 1= 10 times 0.5= 5 6 times 2= 12 5 times 3= 15 So the total number of off spring in that year which is 1 is 27 14 If lambda is greater than one then the population is decreaseing It doesn’t always go back to zero 15 Lamda is relates to expotenial of little r If you are giving lamda be able to caluate little r vice verase An little are is 0.18 16 1. 2. 3. 4. 5. Habitat loss 2. non native (invasive) species Overexploition Pollution Climate change 17 18 19 Vocab 1.Life History: Life history refers to the series of changes an organism goes through during its lifetime, including growth, development, reproduction, and aging. 2.Cost of Reproduction & Resulting Life History Traits: The cost of reproduction refers to the trade-offs an organism faces between allocating resources to reproduction versus other life functions such as growth, maintenance, and survival. Organisms that invest heavily in reproduction may have shorter lifespans or reduced ability to survive in harsh environments. 3.r- and K-Selection: These are two contrasting reproductive strategies. r-selection is characterized by high reproductive rates, small body size, early maturity, and high offspring mortality. K-selection is characterized by lower reproductive rates, larger body size, delayed maturity, and lower offspring mortality. r-selected species typically thrive in unstable or unpredictable environments, while K-selected species are adapted to stable environments. 4.Cohort: A cohort is a group of individuals born around the same time and experiencing the same environmental conditions. 5.nx, bx, sx: These are terms commonly used in population ecology: 1. nx: The number of individuals alive at age x. 2. bx: The age-specific fecundity, representing the average number of female offspring produced by each female in age class x. 20 3. sx: The age-specific survival rate, representing the proportion of individuals surviving from age x to age x+1. 1.Gross Reproductive Rate: This is the sum of bx for all age classes, representing the average number of female offspring produced by a female over her lifetime. 2.Population Projection Table: This table predicts the future size and composition of a population based on its current structure, birth rates, death rates, and other demographic factors. It's used to understand population dynamics, predict population growth or decline, and inform management and conservation strategies. 3.Finite Multiplication Rate (λ): This measures the ratio of the population size in one time period to the population size in the previous time period. It's calculated as the sum of (lx * bx) over all age classes, where lx is the proportion of individuals surviving to age x. 4.Causes of Population Declines and Extinctions: Population declines and extinctions can be caused by a variety of factors, including habitat destruction, pollution, overexploitation, introduction of invasive species, climate change, and disease outbreaks. These factors can lead to decreased birth rates, increased mortality, loss of genetic diversity, and ultimately, the collapse of populations or species. Conservation efforts often focus on mitigating these threats and restoring habitats to prevent further declines and extinctions. 20