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Warm-Up (2/11) On the piece of white paper from the back, answer the following question. (w+) You read about fruit flies having red or white (w--) eyes in last week’s CTQ’s. Flies without red pigment have a mutation in the white gene (w--); flies with the red pigment are considered wild-type (w+). Explain how the allele frequency should change over the course of five generations of a population with an equal distribution of red- and white-eyed flies, if w+ allele has a selective advantage. Name Date Period 2D.3b: Disruptions to ecosystems impact the dynamic homeostasis or balance of the ecosystem. Illustrative example: natural disasters 1C.1a: Speciation rates can vary, especially when adaptive radiation occurs when new habitats become available. 1C.1b: Species extinction rates are rapid at times of ecological stress. Illustrative example: Five major extinctions 1C.2a: Speciation results in diversity of life forms. Species can be physically separated by a geographic barrier such as an ocean or a mountain range, or various pre- and post-zygotic mechanisms can maintain reproductive isolation and prevent gene flow. 1C.2b: New species arise from reproductive isolation over time, which can involve scales of hundreds of thousands or even millions of years, or speciation can occur rapidly through mechanisms such as polyploidy in plants. Speciation Speciation occurs when two groups become reproductively isolated from each other. (1) Physically isolated. Romeo! Juliet! Speciation Speciation occurs when two groups become reproductively isolated from each other. (1) Physically isolated. Speciation Speciation occurs when two groups become reproductively isolated from each other. Eww… feathers! (1) Physically isolated. (2) “Pre-zygotically” isolated (cannot/will not mate) Eww… bald! Speciation Speciation occurs when two groups become reproductively isolated from each other. ¡ay caramba! (1) Physically isolated. (2) “Pre-zygotically” isolated (cannot/will not mate) Speciation Speciation occurs when two groups become reproductively isolated from each other. (1) Physically isolated. (2) “Pre-zygotically” isolated (cannot/will not mate) (3) “Post-zygotically” isolated (offspring dead or sterile) Speciation Speciation occurs when two groups become reproductively isolated from each other. (1) Physically isolated. (2) “Pre-zygotically” isolated (cannot/will not mate) (3) “Post-zygotically” isolated (offspring dead or sterile) Chromosomes don’t match up! Speciation Speciation can happen quickly (like in plants)… Generation 1 No genetic change Whole-genome duplication Generation 2 Speciation Speciation can happen quickly (like in plants)… Let’s start eating fruits more! …or slowly (like when groups find a new environment). Let’s start eating fish more! Critical Thinking Question #1 A population of tree monkeys is only found in a remote forest of Ecuador. In 2005, a drought led to massive forest fires, greatly diminishing the tree monkey population. Describe how speciation could occur in the tree monkey population in the context of genetic drift following the forest fire. (LO 1.24) (LO 2.28) 2D.3b: Disruptions to ecosystems impact the dynamic homeostasis or balance of the ecosystem. Illustrative example: natural disasters 1C.1a: Speciation rates can vary, especially when adaptive radiation occurs when new habitats become available. 1C.1b: Species extinction rates are rapid at times of ecological stress. Illustrative example: Five major extinctions 1C.2a: Speciation results in diversity of life forms. Species can be physically separated by a geographic barrier such as an ocean or a mountain range, or various pre- and post-zygotic mechanisms can maintain reproductive isolation and prevent gene flow. 1C.2b: New species arise from reproductive isolation over time, which can involve scales of hundreds of thousands or even millions of years, or speciation can occur rapidly through mechanisms such as polyploidy in plants. Extinction Extinction is the elimination of a species… …caused by destabilization of an ecosystem. Fleenzauts Fleenzarks Extinction There have been five major mass extinctions caused by massive climate change. Scientists have declared Earth is currently experiencing a sixth mass extinction. Extinctions have occurred at over 1,000 times the background extinction rate since 1900.* *Malcom et al, 2015 Critical Thinking Question #2 201.3 Million years ago (Ma), most marine and terrestrial species became extinct in what is known as the Triassic-Jurassic era. Other species, such as crocodylomorphs, were greatly reduced in population size and genetic variation. Explain how the aftermath of this extinction event might have led to new speciation events. Closure On the piece of white paper from the back, answer the following question: State three situations in which a population could separate into two species. Name Date Period Scale 1 – 10