Zoology: an evolutionary perspective

Standards and Essential Question SZ2b. Explain the concepts evolution, adaptation, natural selection, convergence, and speciation. What makes evolution happen?

What does the word Evolution mean? Organic Evolution Why is it important? Change in the genetic makeup of populations of organisms over time. Source of animal diversity Explains family relationships within animal groups

What does DNA determine? Who is related to who? Evidence of Relation What does DNA determine? Populations are more closely related if they share more DNA. Example: You are more closely related to your brother or sister than your cousin. Most of your physical traits

History of evolution

Who came up with the Theory of Evolution? Charles Darwin Defined evolution as “Descent with Modification” Focused on a mechanism of evolution known as natural selection or “Survival of the Fittest.”

Charles Darwin

Darwin’s Early Years & His Journey Voyage of the HMS Beagle A naturalist Come from a family of physicians Contributed to beetle taxonomy Ventured to the Galapagos Islands (off the coast of Ecuador) Wrote a book based on his discoveries titled “On the Origin of Species by Means of Natural Selection”

Darwin’s Ideas of Evolution Galapagos Islands Organisms Found & Evidence Named after the large tortoises that inhabit them Convinced Darwin that organisms changed over time Galapagos Tortoise – Different shaped shells Galapagos Finches– Different shaped beaks 14 species developed from an ancestral group of finches (adaptive radiation) The difference was due to environmental factors

Natural Selection

4 Basic Principles of Natural Selection Variation Heritability Overproduction Reproductive Advantage

Variation Individuals in a population differ from one another. Increased by mutations and sexual recombination. Example: The students in the classroom all look different.

Heritability Variations are inherited from parents. Example: Will’s children inherited their light skin tone from their father.

Overproduction Populations produce more offspring than can survive. Example: Rabbits produce many offspring at once. Why is it beneficial for rabbits to overproduce?

Reproductive Advantage “Survival of the Fittest” Variations that increase reproductive success and will be more common in the next generation. Example: If bright plumage in peacocks increases reproductive success. What will the peacocks in the next generation have?

Fitness The ability to SURVIVE and REPRODUCE in a given environment. Main concept behind Darwin’s theory of natural selection. The “fittest” is not always the “strongest”

Sexual Selection When intraspecific competition occurs for mates in one sex and when one sex is selected over another as prey by predators Often seen in populations where males and females are significantly different in appearance. Example: Most male birds and their plumage.