General Biology I: Introduction to Ecology (Fall 2024) PDF

GENERAL BIOLOGY 1 8 – INTRODUCTION TO ECOLOGY FALL 2024 Prof : Jules Dumotier Office : F-206  TODAY’S MENU Introduction to ecology  Ecology: The study of interactions between organisms and their environment  Organism-level responses to environmental changes  WHAT’S ECOLOGY Ecology  The study o...

GENERAL BIOLOGY 1 8 – INTRODUCTION TO ECOLOGY FALL 2024 Prof : Jules Dumotier Office : F-206  TODAY’S MENU Introduction to ecology  Ecology: The study of interactions between organisms and their environment  Organism-level responses to environmental changes  WHAT’S ECOLOGY Ecology  The study of interactions between organisms and their environment From the Greek Oikos: House Logos: Study  ECOLOGY Ecology  The study of interactions between organisms and their environment  A deceptively complex field, many variables to consider! V.S.  STARTING SIMPLE Ecology  The study of interactions between organisms and their environment  We’ll start at organism X abiotic factors ORGANISM X ABIOTIC Abiotic factors A-: not  Any factors which aren’t alive -biotic: alive  Common ones to consider:  Temperature  Water availability  Sunlight exposure  Substrate type (soil)  ORGANISM X ABIOTIC Response to abiotic factors  (strict) Homeostasis  Maintain internal environment stable despite abiotic factors Oh, hell nah!  What you and I (and many animals) do Physical/ Chemical Set point factor Time ORGANISM X ABIOTIC Response to abiotic factors  Conformer (flexible homeostasis)  Change (within reason) along with your environment  Usually only for a few parameters (ex: °C but not pH)  Many animals, most plants Maintaining a more “permissive” homeostasis can save precious energy ORGANISM X ABIOTIC Response to abiotic factors  Three broad ways to respond 1. Physiological response Oh, hell nah! 2. Morphological adaptation 3. Behavioral response  RESPONSE TO ABIOTIC FACTORS Temperature shifts  Your metabolism is fine tuned for a narrow range of °C 1. Physiological response  You will sweat (↓°C) or shiver (↑°C) Remember, water has a high heat of evaporation (takes a lot of energy) RESPONSE TO ABIOTIC FACTORS Temperature shifts  Your metabolism is fine tuned for a narrow range of °C 1. Physiological response  You will sweat (↓°C) or shiver (↑°C) Animals with fur cannot sweat! RESPONSE TO ABIOTIC FACTORS Temperature shifts  Your metabolism is fine tuned for a narrow range of °C 1. Physiological response in conformers  Some frogs burry themselves and/or freeze in winter  Once frozen their metabolism comes to a halt saving them a lot of energy If you were to freeze, ice crystals would tear your cells up RESPONSE TO ABIOTIC FACTORS Temperature shifts  Your metabolism is fine tuned for a narrow range of °C 1. Physiological response in conformers  Many frogs burry themselves and/or freeze in winter  BUT: they produce their own antifreeze!  ↑↑↑ glucose within their tissues prevents organs freezing Conforming doesn’t mean doing nothing! RESPONSE TO ABIOTIC FACTORS Temperature shifts  Your metabolism is fine tuned for a narrow range of °C 2. Morphological response  Ex: Fur thickening/shedding RESPONSE TO ABIOTIC FACTORS Temperature shifts  Your metabolism is fine tuned for a narrow range of °C 3. Behavioral response  Many animals simply move to more suitable conditions I’m out! Nothing like a good sunbath! ADAPTATION TO ABIOTIC FACTORS Temperature adaptations  Endotherms can generate heat internally  Mainly through basic metabolism (mitochondria), muscles and specialized fatty tissues  Mostly birds & mammals Lampris australensis Pro: can tolerate a wide range of °C Con: uses a lot energy  ADAPTATION TO ABIOTIC FACTORS Temperature adaptations  Ectotherms need external sources of heat  Typically relies on the sun  Includes most insects, reptiles, fish and amphibians Pro: uses less energy (need less food) Con: less tolerant to temperature shifts  ADAPTATION TO ABIOTIC FACTORS Temperature adaptations 𝑺𝒖𝒓𝒇𝒂𝒄𝒆  Size is linked to to control heat exchanges 𝑽𝒐𝒍𝒖𝒎𝒆  Allen’s rule: extremities (hears, tail, limbs) are shorter in cold climates and longer in hot climates Loxodonta africana Mammuthus Vulpes zerda Vulpes lagopus primigenius ADAPTATION TO ABIOTIC FACTORS Temperature adaptations Ursus maritimus ~2m & 600kg 𝑺𝒖𝒓𝒇𝒂𝒄𝒆  Size is linked to to control heat exchanges 𝑽𝒐𝒍𝒖𝒎𝒆  Bergman’s rule: animals are bigger in cold climates and smaller in hot climates Ursus thibetanus ~1.5m & 100kg RESPONSE TO ABIOTIC FACTORS Water availability  Biodiversity tends to be higher in humid ecosystems  RESPONSE TO ABIOTIC FACTORS Water availability  All organism need water Behavioral & morphological response  In the Namibian desert, Onymacris unguiculari does a headstand in the morning fog to capture condensation  The beetle’s elytra (wing cover) feature grooves Onymacris unguiculari which help direct water droplets to its mouth  Paramecium caudatum RESPONSE TO ABIOTIC FACTORS Water availability  All organism need water but not too much Physiological response  Paramecium caudatum (a freshwater eukaryote) uses its contractile vacuoles to get rid of excess water  RESPONSE TO ABIOTIC FACTORS Sunlight exposure  All phototrophs need sunlight Physiological response  Leaves feature many pigments to capture a wider spectrum and protect against UVs  As sunlight exposures diminishes in fall, deciduous trees will “recycle” most of their chlorophyll  Fall colors are simply the left-over pigments RESPONSE TO ABIOTIC FACTORS Sunlight exposure  All phototrophs need sunlight Morphological response  Leave size and thickness is often associated with a plants natural niche within the forest  Underbrush plants usually have larger and thinner leaves to maximize photosynthesis RESPONSE TO ABIOTIC FACTORS Sunlight exposure  Sunlight is also useful to some chemoheterotrophs  Vitamin D production is a complex pathway involving the liver, kidneys and... sunlight (UVs)! Behavioral response  Most governments have implemented laws mandating dairy products to be fortified with vitamin D (among others) RESPONSE TO ABIOTIC FACTORS Substrate type (soil)  Consistency, mineral composition and pH of soil are important to plants and soil dwelling eukaryotes  Soil type is a key part of any ecosystem HENRY SCHREIBER All types of responses  Plant growth patterns and even colors change based on substrate type ORGANISM X ABIOTIC Response to abiotic factors  Conform: bear with some internal changes  Strict homeostasis: use more energy to keep everything stable  Three broad ways to respond Oh, hell nah! 1. Physiological response 2. Morphological adaptation 3. Behavioral response