Chapter 17 Review - TMHS Putnam PDF

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Chapter 17 Review Introduction to Chapter 17 ● Population - Group of organisms of the same species occupying a certain area and sharing a common gene pool ● Understanding how a population, over time, accumulates differences large enough to become a new species ● The origin of species is key to understanding the origin of the diversity of all life on Earth. ● Species - Group of similarly constructed organisms capable of interbreeding and producing fertile offspring; organisms that share a common gene pool Key Concepts for Chapter 17 ● Macroevolution, or the origin of species, results from the accumulation of microevolutionary change over time. ● Evolutionary geneticists research and document the genetic basis of phenotypic changes that can lead to speciation. ● New species can arise from specialization for a particular habitat or microhabitat. Chapter 17 Section 1 Summary: How New Species Evolve ● The morphological species concept identifies species based on (appearance) diagnostic (physical) traits. ● The evolutionary species concept requires that each species have its own evolutionary pathway and can be recognized by certain diagnostic morphological traits. ● The phylogenetic species concept recognizes a new species as a set of populations that share a common ancestor, or are monophyletic on an evolutionary tree. ● The biological species concept identifies a species based on whether two or more populations are reproductively isolated from each other. ● Reproductive isolation -

Prezygotic isolating mechanisms (habitat, temporal, behavior, mechanical, and gamete isolation) - Prevent mating from being attempted or prevent fertilization from being successful if mating is attempted.

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Postzygotic isolating mechanisms (hybrid inviability, hybrid sterility, and F2 fitness) Prevent hybrid offspring from surviving or reproducing

Chapter 17 Section 2 Summary: Modes of Speciation ● Allopatric speciation - Geographic or physical separation precede reproductive isolation. Isolation of populations allows genetic changes to accumulate over time via microevolution. Eventually, the ancestral species and the new species no longer breed with one another. ● Sympatric Speciation - A geographic barrier is not required, and speciation is simply a change in genotype that prevents successful reproduction. This is relatively rare in animals, but can occur when populations of the same species become specialized on a particular sub habitat and/or food item in the same geographic area. Example - Polyploidy in plants - having a chromosome number that is a multiple greater than twice that of the monoploid number ● Adaptive Radiation - a type of speciation that occurs when a single ancestral species rapidly gives rise to a radiation of new species as each adapts to a specific environment. ● Convergent evolution - when the same biological trait has evolved in two unrelated species as a result of adaptation to a similar set of conditions or lifestyles. Example - the wings of birds and bats Chapter 17 Section 3 Summary: Principles of Macroevolution ● Macroevolution - is evolution of new species and higher levels of classification Concepts from Chapter 17 ● Microevolution is the change in the allele frequencies of a population over time. Macroevolution is what happens when microevolutionary change accumulates until speciation occurs. ● Evolution does not have direction. Variation arises by random mutation, not because a particular solution is needed. ● An ecological or physical barrier promotes allopatric speciation. Microhabitat specialization drives sympatric speciation. ● Microhabitat specialization is a common characteristic of adaptive radiation. ● In similar environments, similar features may evolve in unrelated organisms

through convergent evolution....