Week 9 - Evolution + DDT PDF

SC253: Ecology and Environmental Problems October 28, 2024 Prof. Amy L. Frick  Agenda Discuss panel presentations Lecture: Evolution [break] The Day they Parachuted Cats into Borne...

SC253: Ecology and Environmental Problems October 28, 2024 Prof. Amy L. Frick  Agenda Discuss panel presentations Lecture: Evolution [break] The Day they Parachuted Cats into Borneo; Biological magnification Group activity: mesocyclops  Housekeeping ( 1. Your ecological footprint essay was due on October 21. If you have not handed it in yet, please do so ASAP. 2. You will participate in a ~20 minute panel presentation on November 18 or November 25. Topics will be randomly assigned. On the day that you’re not presenting, you will write a thoughtful peer-review of a classmate’s presentation. Date preferences for panels are offered to those with extenuating circumstances only; if you will not be here on one of those dates, you must let me know by November 4 (next week). If you’re a no-show on the day of the presentation, you will get a 0 and will not be allowed to make it up.  Schedule October 28: Evolution, biological magnification, mesocyclops, et al. November 4: Carbon, climate change November 11: Water; nitrogen November 18: Presentations - Day 1. November 25: Presentations - Day 2. December 2: Final exam December 9: No class meeting. Last day to submit overdue assignments.  Topic: “Cats are better than dogs” 1. Introduce the topic, along with its significance. Explain what you’ll be discussing and define unfamiliar terms. (1-2 minutes) 2. Pro (Cats are better than dogs): Discuss your position. Present evidence. (4-5 minutes) 3. Con (Cats are not better than dogs): Present counter arguments. Provide evidence.(4-5 minutes) 4. Pro: Respond to Con arguments. Offer your own analysis. (2-3 minutes) 5. Con: Respond to the Pro speaker (optional). Summarize your overall position. (2-3 minutes) 6. Q&A: Be prepared to discuss. You will be asked what your position is on the topic after having prepared for the panel discussions.  Evolution A change in gene frequency from one population to the next  Evolution A change in gene frequency from one population to the next Selective forces: Random mutation Gene flow Genetic drift Selection  No variation = no evolution Generation 1 Generation 2 Generation 10 Generation 100  + Random mutation New trait appears! Variation. Generation 1 Generation 2 Generation 10 Generation 100  + Gene flow The movement of genes from one population to another (Genes flowing from one population into another) Generation 1  + Gene flow The movement of genes from one population to another Generation 2  + Gene flow The movement of genes from one population to another Generation 100  Genetic drift In each generation, some individuals may, just by chance, leave behind a few more descendents (and genes, of course!) than other individuals. The genes of the next generation will be the genes of the "lucky" individuals, not necessarily the healthier or "better adapted" individuals. Random occurrence!  Genetic drift Example 1: Founder effect Example 2: Bottleneck effect Founder effect Generation 1 Small group of individuals colonizes a new area  Founder effect Generation 100 New population has different proportion of genes than original population  Bottleneck effect Population bottlenecks occur when a population's size is significantly reduced for at least one generation. Genetic variation is significantly decreased in the remaining, now small, population. The genetic variation in future generations will reflect the allele frequency of the founding group. Examples: Bottleneck effect [survivors] Random event reduces population size  Bottleneck effect Generation 100 (after volcano) New population has different proportion of genes than original population  Natural selection Fitness: nature selects individuals with traits that are best suited for survival in its environment. These traits are passed on from generation to generation. ○ Fitness: What is fitness? Fitness includes the abilities to: survive find a mate produce viable offspring Ultimately, the ability to pass on one’s genes to the next generation. Fitness includes the abilities to: survive find a mate produce viable offspring Ultimately, the ability to pass on one’s genes to the next generation. The fittest individual is not necessarily the strongest, fastest, or biggest.  Fitness Some individuals are better capable of surviving and producing offspring than others. An organism's fitness depends on the environment in which it lives. The fittest organism during an ice age, for example, is probably not the fittest once the ice age is over.  Natural selection Lots of green bugs for everyone to eat.  Natural selection Now only blue bugs are available. You have to HEAR them to catch them.  Natural selection Pointy ears = better hearing = advantage! More pointy-eared animals survive and reproduce....The population evolves to include mostly pointy-eared creatures. (Having pointy ears is an adaptation)  Natural selection Important*: Variation already exists….  Natural selection Important: Variation already exists…. Environment determines which traits are favorable.  Natural selection Important: Variation already exists…. Environment determines which traits are favorable. The best adapted individuals survive and reproduce. (having pointy ears = adaptation)  Natural Selection Important: Variation already exists. The environment determines which traits are favorable. [Peppered moths] Could human activity alter the environment? Co-evolution/co-adaptation https://www.youtube.com/watch?v=iyvXZcWUbI0 Co-evolution: bees/flowers  Artificial selection: Corn Link to journal article about IGF-1 in dogs Artificial selection: IGF-1 levels in dogs Link to journal article about IGF-1 in dogs Co-evolution/ Co-adaptation https://www.youtube.com/watch?v=BalxcRtP-m4 GMOs What if humans alter individual species? Part II: mosquitoes and dengue  Concept: biological magnification Biological magnification: the process by which toxic chemicals and heavy metals increase in concentration as they move up a food chain Biological magnification  Natural Selection Important: Variation already exists. The environment determines which traits are favorable. Could human activity alter the environment?  Natural Selection Variation for any given trait is already present in a population. (Multiple variants of Glutathione S transferase (GSTe2) gene  Natural Selection Red variant of Glutathione S transferase (GSTe2) gene confers resistance to DDT! [DDT]  Natural Selection Red variant of Glutathione S transferase (GSTe2) gene = advantage! More of these mosquitoes survive and reproduce. [DDT]...The population evolves to include Red-GSTe2 mosquitoes. [DDT-resistant mosquitoes]  Mesocyclops Sustainable natural pest control?  Group activity (~5 minutes per group). Each group member will be expected to speak, so plan accordingly. What should be considered when assessing the sustainability of the use of mesocyclops for natural pest control? What should be considered when assessing the sustainability of the use of mesocyclops for natural pest control? Are there other alternatives? Effects on drinking water? Dead mesocyclops/larvae? Need for filtration? Health effects Parasite in mesocyclops? Effect on human health? Other wildlife/fish/etc? Effect on other mosquito-borne illnesses Potential to cause disease? Ecosystem Does mesocyclops invade other parts of the ecosystem? Effects on livestock, crops, etc? Food chain? Logistics/Implementation How many mesocyclops needed? Cost? How are mesocyclops transported? Maintenance of appropriate conditions for mesocyclops Lifespan of mesocyclops? Need for replacement annually? How to control mesocyclops population? How long until it works? For how long does it work? Social How to distribute information, get participants, etc? Will this intervention create a new job? Fall 2024/306 What should be considered when assessing the sustainability of the use of mesocyclops for natural pest control?  Housekeeping (recap) ( 1. Your ecological footprint essay was due on October 21. If you have not handed it in yet, please do so ASAP. 2. You will participate in a ~20 minute panel presentation on November 18 or November 25. Topics will be randomly assigned. On the day that you’re not presenting, you will write a thoughtful peer-review of a classmate’s presentation. Date preferences for panels are offered to those with extenuating circumstances only; if you will not be here on one of those dates, you must let me know by November 4 (next week). If you’re a no-show on the day of the presentation, you will get a 0 and will not be allowed to make it up.