Animal Biology: Metabolic & Sexual Selection Concepts Recap PDF

Concept of symmorphosis Biological systems have a quantitative match between their design and function. Qualitatively, the likelihood of match between biological structures and their functional requirements is obvious; exactly how good this match should be is less obvious. Adequacy or...

Concept of symmorphosis Biological systems have a quantitative match between their design and function. Qualitatively, the likelihood of match between biological structures and their functional requirements is obvious; exactly how good this match should be is less obvious. Adequacy or sufficiency, rather than optimality, is the most likely evolutionary outcome because natural selection tends to maximize relative, not absolute, fitness.  Compression bridge Suspension bridge Three parameters can be changed when the size of a structure is to be increased: Thickness Material Design  What principles make animals functional? Advantages of a certain size, material, and design Limitations and constraints imposed by each of these three physical parameters. Allometric scaling explains how different biological traits (like metabolic rate, growth, lifespan) scale with the size (or body mass) of an organism. Relationship between an animal's metabolic rate (MR) and its body mass (M). MR = aMb MR, metabolic rate, the rate at which an animal consumes energy (oxygen). M, body mass of the animal. a, constant that varies between species and other environmental or physiological factors. B, scaling exponent that describes how metabolic rate changes with body mass.  Allometric scaling in animals Allometric scaling useful to understand how body size of different species influences energy use  Kleiber’s law or 3/4-power scaling law refers to a biological phenomena where the metabolic rate of most organisms scales with body mass according to the equation: MR=aM3/4 a is a constant, M is body mass, and the exponent 3/4 represents the scaling exponent. This means that as the body mass increases, its metabolic rate increases, but at a rate slower than the increase in body mass. Relationship between body mass (M) and metabolic rate (MR) for different values of the scaling exponent b: Super-linear scaling (b=1.2); MR increases faster than body mass. Rare in nature. Linear scaling (b=1); MR increases directly in proportion to body mass. Sub-linear scaling (b=0.75); MR increases more slowly than body mass, flattening as body mass grows. Most common in nature. Conclusion: Metabolic Scaling Core Concepts Recap: Definition: Metabolic scaling refers to the relationship between the size of an organism and its metabolic rate. Key Principles: 1.Metabolic rate scales with body size (e.g., larger animals often have lower metabolic rates per unit mass). 2.The allometric scaling laws (e.g., Kleiber’s law: metabolic rate scales to the 3/4 power of body mass). Implications: 1. Ecological Impact: Understanding metabolic scaling helps in predicting energy requirements and ecological roles of different species. 2. Evolutionary Insights: Provides insights into evolutionary adaptations related to size and metabolism. 3. Practical Applications: Useful in fields like conservation biology, medicine (e.g., drug dosing), and agriculture. Core Concepts Recap: Sexual Selection Definition: Sexual selection is a type of natural selection where individuals with certain traits are more likely to obtain mates and reproduce. Mechanisms: 1. Intra-sexual selection: Individuals select mates based on specific traits or behaviors, which can be indicative of genetic quality or fitness (e.g., peacock feathers, bird songs). 2. Intersexual Competition: Members of the same sex compete for access to mates, often through physical contests or displays of dominance (e.g., stag antlers, fights among males). Key Concepts: 1. Fitness: Traits favored by sexual selection often enhance an individual's reproductive success rather than survival (e.g., elaborate plumage in birds may attract mates but make them more visible to predators). 2. Sexual Dimorphism: Differences between sexes in traits related to mating (e.g., size, coloration, ornamentation) often arise due to sexual selection. 3. Runaway Selection: A positive feedback loop where a preference for a particular trait leads to increased elaboration of that trait over generations (e.g., the extreme tail length of some bird species). Theories: 1. Good Genes Hypothesis: Individuals choose mates based on traits that signal high genetic quality, which will be passed on to offspring. 2. Resource-Based Theories: Mate choice is influenced by the resources or benefits that the mate can provide (e.g., territory, food). Eusociality Core Concepts Recap: Definition: Eusociality is the highest level of social organization, characterized by cooperative brood care, overlapping generations, and a division of labor into reproductive and non-reproductive roles. Key Examples: Includes ants, bees, wasps, and some species of termites and naked mole rats. Key Features: 1. Cooperative Brood Care: Non-reproductive individuals help care for offspring produced by reproductive individuals. 2. Reproductive Division of Labor: Clear differentiation between reproductive individuals (queens, kings) and non-reproductive individuals (workers, soldiers). 3. Overlapping Generations: Multiple generations live together and contribute to the colony’s care and survival. Evolutionary Significance: 1. Inclusive Fitness: Eusociality is often explained by the concept of inclusive fitness, where individuals increase their genetic contribution to future generations by helping relatives. 2. Adaptation: Eusocial behavior provides advantages such as increased survival rates and enhanced ability to exploit resources. 3. Behavioral Insights: Understanding eusociality sheds light on the evolution of complex social behaviors and cooperation.