Evidence for Evolution I like to show pictures and ask questions before actually talking about the topic to see if the students can answer and find out on their own.

Biogeography The scientific study of the geographic distribution of organisms based on both living species and fossils. What do you see in this picture? Do you think turtles or other organisms would act the same way if you were this close to them? (They might say yes and give examples of pigeons, sea gulls, racoons in the city that aren’t scared – ask them why they’re like that... What’s different about them vs. wild animals)? Why would this turtle not be afraid of humans? (no natural predators)

Biogeography Darwin found on the Galapagos that there was an unusual assortment of species which also holds true for other remote islands such as Hawaii and New Zealand. One observation Darwin made was the animal behaviour on these islands He found that the species were fearless He believed this could be accounted for by evolution and not having any natural predators

Darwin’s Hypotheses The pattern he observed were evidence that species might have evolved He hypothesized that remote oceanic islands became populated by species that arrived by water or air After they arrived, they evolved to new species over time

Darwin’s Hypotheses Observations from the Galapagos Islands Darwin’s hypotheses regarding remote islands Many species of plants, birds, insects and, in some cases, reptiles Only these kinds of organisms are able to reach remote islands by crossing large expanses of open ocean No native amphibians and very few land mammals Amphibians and most mammals are unable to cross open ocean and will not be found on remote islands Many unique species found no where else on Earth Over time, ancestral species have evolved into new geographically isolated species Unique species most closely resemble species on the nearest continental mass Unique species are descendants of ancestral species from the nearest continental masses and will exhibit some similarities

By doing further tests for his observations, we wanted to see if he was correct Hawaiian islands were formed from volcanoes - have a wide range of habitats and have never been connected to any other land mass The native species on the hawaiian islands supports darwin’s hypotheses No native amphibians or mammals, with the exception of bats and sea lions Many species of unique plants, birds and insects No native terrestrial reptiles Only native reptiles are marine species: sea snake and five species of sea turtles What about is remote islands lack the environment for introduced organisms. Is this true? – what do we know about introduced species and how they affect an environment? (example of honeycreeper being wiped out by introduced species)

Homologous Features Are these the same? Are they related? What do you notice about the features of each of these organisms? What does this mean about our relationship with each other? (we’re related somehow, common ancestor)

Homologous Features A structure with a common evolutionary origin that may serve different functions in modern species (Ex. All mammals have 28 skull bones, 7 neck bones) Neck bones are the same in mammals, but they look different because depending on the organism, the function of the neck varies. (ie. In marine mammals, part of the neck is fused)

Homologous Features Darwin knew that many traits were inherited from generation to generation (either naturally or artificially) Closely related species share homologous developmental processes and patterns as well. 􀂃 Similar structure 􀂃 Similar development 􀂃 Different functions 􀂃 Evidence of close evolutionary relationship 􀂋 recent common ancestor

Homologous Features What do you notice about these organisms? Do they look the same? Different? When do they start to look different? This still supports Evolution because there are still commonalities in development between similar groups of organisms. Examples: The backbone is one of the earliest structures to appear in all vertebrates. Tails in humans and legs/hair in whales appear and then disappear later in development.

Analogous Features What’s common about these? Same function What’s different? Different structure

Analogous Features A structure that performs the same function as another but is not similar in origin or anatomical structure Their features evolve independently of each other 􀂃 Separate evolution of structures 􀂋 similar functions 􀂋 similar external form 􀂋 different internal structure & development 􀂋 different origin 􀂋 no evolutionary relationship

Vestigial Features Eyeless cave fish, kiwi, appendix, pelvis of a whale What are these organisms missing? Why would they be missing these structures?

Vestigial Features A rudimentary and non-functioning, or only marginally functioning, structure that is homologous to a fully functioning structure in closely related species

Vestigial Features They no longer serve a function In ancestors they served a useful purpose, but had become useless or distorted as the species evolved Ex. Goosebumps Why do we get goosebumps? Are they helpful to us today? What does it do to your skin? What if you have hair on your arm or somewhere else on your body? Vestigial Structures are those structures still present in an organism, but serve no current purpose. They were once useful in an ancestral organism from which the current organism evolved, thus they are proof of evolution. What purpose might have they served (defense, warmth)

How many eggs did this frog lay? Will all of them survive? Why or why not? What are reasons not all of them will survive?

Competition within Populations Darwin wondered if nature might be able to favour certain individuals in a population Darwin learned from a paper from a man named Reverend Thomas that all populations were limited in size by their environment

Competition This resulted in competition for space in the environment within a species This is because they are fighting for the same resources This is called intraspecific competition Can you name other example of intraspecific competition?