UNIT 3 EVOLUTION OF ANIMALS Mrs Stahl Star

UNIT 3 - EVOLUTION OF ANIMALS Mrs. Stahl

Star Nosed Mole � Has a pink snout that is especially good at finding food. The snout’s 22 fingerlike projections can touch up to 12 objects in just one second. The mole uses it’s paddle shaped feet for burrowing, and its large ear openings give it excellent hearing. Has very poor vision. How could evolution lead to this?

� � It forages at a rate so fast that the human eye can barely register them. They have been recorded at eating prey at 1/4 th of a second. Hypothesis- the reason they eat so fast is the fact that its prey is so tiny, the mole must eat twice as fast as animals that eat larger prey.

Answers � How do these traits arise in the first place? �Mutations that have been passed down from generation to generation

? ? ? ? ? � What other factors could have contributed to the star nosed moles distinctive features over generations? �Changes to their environment �Prey �Competing organisms

Activity � � In front of you there a series of pictures. Look for pictures of animals that share physical features (examples wings, horns, claws) but are not necessarily closely related. You decide the type of group!!!! Look at the physical characteristics. You have 5 -10 minutes to complete this. Present to class and give reasons for the choices you made.

Questions? ? ? � � 1. What is the source of the shared characteristics in closely related species? 2. Why do distantly related species share similar traits?

Answers � � 1. Shared genes 2. They occupy similar environments and therefore may need similar features to move, feed, find shelter, and survive

Answers � � 1. Shared genes 2. They occupy similar environments and therefore may need similar features to move, feed, find shelter, and survive.

Evolution � Process of biological change by which descendants come to differ from their ancestors.

Species � A group of organisms so similar that they can reproduce and have fertile offspring.

Population � Group of the same species that live in the same area at the same time. They share unique set of genes.

The History � � Started with the Greeks Empedocles (495 -435 BC) and Aristotle (384 322 BC)-> described concepts of change in living organisms over time. Carolus Linnaeus (1700’s)-> developed a classification system for all organisms at that time based on similarities. George Lewis Buffon (1707 -1788)-> studied comparative anatomy relationships among organisms and biological variation.

History Continues � Erasmus Darwin (1794 -1796)- Darwin's grandfather. He said that all living things were descended from a common ancestor.

Jean Baptiste Lamarck � � Jean Baptiste Lamarck (1809)- zoologist who studied animal classification, theory of inheritance> organisms develop new organs or modify existing organs, as the need arises. If they do not use them then the organs degenerate and are changed based on environmental conditions. Also believed that animals did not become extinct but evolved into new animals. Ex- giraffe= ancestral giraffes had short necks (like other mammals) but they strained to reach higher branches during feeding which resulted in acquiring higher shoulders and necks.

Lamarck � � � Criticized heavily for this idea We now know that it is not correct because there is no evidence that changes in the environment can initiate changes in organisms that can be passed on to future generations. Change originates in the process of gamete formation. Random changes in DNA such as mutations, and chance processes involved in the assortment of genes into gametes (sex cells) result in a variation of offspring. The environment plays a role in determining the survival of these variations.

Darwin � Darwin believed that giraffes evolved by which the gene for long necks became dominant over the gene for short necks. Giraffes with short necks died out and giraffe with long necks survived.

Common Terms � Fossils- traces of organisms that existed in the past. The deeper they are found in the rock layers, the older they are.

How some species were altered: � � � 1. Catastrophism- natural disasters such as floods and volcanic eruptions have happened often during history shaped landforms -> caused species to become extinct. These are sudden disasters. 2. Gradualism- slow changes over a period of time. Ex- Pangaea 3. Uniformitarianism- geologic process that shaped Earth are uniform through time. Uniform= staying the same.

Catastrophism � Volcanoes, earthquakes, and floods = Mass Extinctions.

Gradualism � Canyons carved by rivers show gradual change. Changes occur in small steps over time.

Uniformitarianism � Rock strata demonstrates the geological processes, which over time shows great change.

It really all began in the Galapagos Islands!!!! http: //www. youtube. com/watch? v=CCIac. O e. B 9 cs

The Galapagos � � Named for the Galapagos tortoises Tortoise shells were different in different parts of the Albemarle Island. Drier regions= the tortoises had longer necks. There was high growing vegetation in those regions. Wetter regions= the tortoises had shorter necks. There was low growing vegetation.

How could these overall similarities be explained? � � The tortoises on the islands derived from a few ancestral animals that traveled from the mainland. There is no connection to the mainland (900 km away = 559 miles). The Galapagos are volcanic and arose from the seabed. They have never touched the mainland. Hypothesis- tortoises floated on mats of vegetation that regularly break free from the coastline during storms. The tortoises didn’t have any predators = high population.

Darwin’s Finches � Also found on the Galapagos Islands. � 1 species turned into 14 different species � Originals probably fed on seeds and now some feed on plants, insects, seeds, and cactus.

What allowed this to happen? � � Open habitats and few predators allowed the radiation of finches into 14 different species. Adaptive radiation= formation of new forms from an ancestral species usually in response to the opening of new habitats. Each species is adapted to a specific habitat on the islands. Biggest difference = diet, which was reflected in the size and shape of their bills.

Videos � � http: //www. youtube. com/watch? v=03 YKT 7 yt. Jd E http: //www. youtube. com/watch? v=FT 3 FU 2 XOgo&feature=bf_prev&list=PL 8 D 27 E 2 A 18 D 8 C 3 A 7 F

Conclusion from the Galapagos � Finches and tortoises convinced Darwin that animals change over time.

Fun Fact � The world’s oldest living animal- Harriet, a Galapagos Island tortoise- was once Charles Darwin’s shipmate. She was one of three Galapagos tortoises captured by Darwin during his expedition. Darwin took the animal back to England, and thinking all three were males, named them Tom, Dick, and Harry. The animals were poorly adapted to the cool English climate, the animals were moved to Australia around 1840. In the 1960’s scientists realized that Harry, the last remaining member of the trio, was actually a female. In 1992, DNA testing suggested that Harriet was born around 1830. Harriet lived at the Australian Zoo until her death in 2006. She was around 176 years old.

Group Activity- Scenario � � � Sea lions in the Galapagos suddenly lose their main food source when changes in sea temperatures and currents keep anchovies away from the islands. The only food available is small species of crab that lives on the sea floor, 100 feet below the surface. 1. What traits in the sea lion population might be adaptive? 2. How would the population change?

Adaptive traits � � 1. They could travel for days to find sardines. 2. El Nino is the result of changes in wind patterns and ocean currents that occur occasionally in the winter. The warm tropical water moves eastward across the Pacific and accumulates along the North and South American coasts. Hard on places like Ecuador and the Galapagos because they are highly productive areas with nearly constant upwelling of deep, nutrient-rich water. Outcome- warm water kills cold water organisms that are the basis of the food chains for many marine birds, mammals, and fishes. The loss of food causes the death of these animals or the animals relocate. http: //video. nationalgeographic. com/video/environment-naturaldisasters/landslides-and-more/el-nino/

Adaptive Traits � 3. Streamlined body allows them to swim fast and efficiently.

How would the population change? � � � Survival of the fittest. They either adapt to survive or die. Pups may have the hardest time because they are just learning to swim and hunt. They may die off faster than the adults. Adults may leave the area and travel to where there is food.

Bring it all together…. � Write a brief description summarizing the scenario on a separate sheet of paper.

Theory of Natural Selection � � Defined as-> individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals. Darwin came up with this after reading Thomas Malthus’ essay entitled “Essay on Principles of Population. ” � He stated that the human population has the potential to increase by doubling or by some other multiple rather than by adding a fixed # of individuals.

Therefore…. . Resources can’t keep up, therefore things / factors such as poverty, wars, plagues, and famines begin to influence populations. � Darwin put it together that a similar struggle occurs in nature -> Natural Selection �

Theory of Natural Selection 4 Major Principles � 1. All organisms have a greater reproductive potential. � Example- Oysters release 100, 000 eggs � Example- Female sea star releases about 1 million eggs. � Example- Robin lays four fertile eggs each season. �What would happen if all of these eggs were fertilized and developed to reproductive adults? What would happen to the resources?

Answer � Overpopulation � No room in the habitats � Competition for resources such as food, mates, habitats, etc.

2. Inherited Variation � � Arises from a variety of sources such as mutations, genetic recombination (crossing over), and random fertilization. Some genetic variations may confer an advantage to the individual that has them. Some may be harmful like severe mutations.

3. Resources are Limited � � Existence is a constant struggle Many individuals die because there are too many and not enough resources. Individuals that die are those with traits that make successful reproduction less likely. Traits that promote successful reproduction are adaptive.

4. Adaptive Traits � � Become more common from generation to generation. Example- Hummingbirds long bill.

Adaptive Traits in Animals � 1. Thorn Bug �Thorn Bug- makes predators less likely to eat them.

#2 Galapagos Tortoise � Adapts to different habitats and feeding strategies.

#3 Jaguar � � � Large teeth and jaws -> eat shelled reptiles. They will have more offspring and survive than the ones that can eat only mammals. Over generations these heritable traits became more common.

#4 Pufferfish � Inflates when threatened by a predator. https: //www. youtube. com/watch? v=Ok. Xh. C 7 yz. ISI

# 5 – Snow Monkeys / Japanese Macaque � Learn to wash their potatoes before eating them by imitating the behavior of others. https: //www. youtube. com/watch? v=eu. Ml. L 9 O 1 Kc

# 6 - Eagle Owl � Broad wings are adapted for silent flight -> nocturnal bird that’s quiet and a deadly predator. � Wings that produce flight � Strong flight muscles that move wings � Active metabolism-> energy for muscles � Hollow bone structure (less weight) � Reproductive adaptations https: //www. youtube. com/watch? v=ynl. L 8 L 3 Ui 8

# 7 - Water holding frogs � Live in dry grasslands / desert Australia (1 rainy season). Dry periods last for about 10 months where the frog burrows underground. They form a cocoon with their shedded skin to keep moisture in when it rains-> they crawl out to mate-> females lay eggs in puddles-> after two weeks eggs hatch into tadpoles. If they don’t adapt, they die.

https: //www. youtube. com/watch? v=tu. Wo_k https: //www. youtube. com/watch? v=vtwu. LWMihs zn. El. Q

# 8 - Panda Bear � � Some structures take new functions- adaptive compromise. Have a structure in their wrist that acts like a thumb. It looks like they have six digits (five look like fingers), but one is thumb-like and is actually an enlarged wrist bone.

� The bone is actually called a sesamoid bone and is small and round. Your kneecap or patella is also a sesamoid bone that functions as a pulley systemincreasing leverage of the tendon as it moves across the joint. five digits wrist bone

Pandas � � https: //www. youtube. com/watch? v=006 ip 4 nd. Th E https: //www. youtube. com/watch? v=a. Kh 3 kzx. U 0 6 Q

Theory of Natural Selection History - What led to this theory? � Artificial Selection � Heritability � Natural Selection

Artificial Selection � � Humans change a species by breeding it for certain traits. Humans decide which traits are favorable and then breed those individuals that show those traits. neck feathers crop tail feathers

Heritability � � Ability of a trait to be passed down from one generation to the next. Key factor in making artificial selection possible. Humans must breed the desirable traits such as neck feathers, large crops, or extra tail feathers in pigeons. Humans don’t let it “just happen” they are the selective agent not the environment.

Natural Selection � � Individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals. Environment is the selective agent- only the strong / advantageous characteristics are passed on to future generations.

The Principles of Natural Selection � 1. Variation � 2. Overproduction � 3. Adaptation � 4. Decent with Modification

Variation � � Individuals differ because the genetic material is different, whether inherited from the parents or resulting from a genetic mutation. Ex- Jaguar. See attached example sheet in notes.

Overproduction � Producing too many offspring at one time. They won’t all survive because they will die off while competing for resources.

Adaptation � Certain variations or characteristics allow an animal to survive better than other individuals.

Descent with Modification � Over time, species with adaptations that are well suited for the environment in which they live in, will survive and reproduce more than others.

Example- Jaguars � � � 11, 000 years ago many jaguars faced extinction due to lack of food because the climate was changing. The amount of mammals available to feed on was limited, therefore the jaguars had to adapt to eat reptiles. What became the important adaptation? - the size of their teeth and jaws. The jaguars with the largest teeth and biggest jaws could prey more easily on these hard shelled reptiles, that when they had offspring, their offspring inherited these traits. The descendents showed modifications / changes over time.

Evidence of Evolution Fossils � Geography / Biogeography � Embryology � Comparative Anatomy � �Homologous Structures �Analogous structures �Vestigial structures

Fossils � � Person who studies fossils= Paleontologist Defined as- the remains of plants and animals that lived in the past. Formed in sedimentary rock layers called strata. The oldest are found in the deep rock layers while the youngest or most recent animals are found closer to the surface-> fossilized in sand, sediment, or volcanic ash. Most fossils are found near aquatic / semi aquatic regions.

Skeleton of Basilosaurus isis in Egypt. Lived 40 mya and had both land marine characteristics.

� Paleontology provides evidence to support evolution.

Molecular and genetic evidence support fossil and anatomical evidence. � Two closely-related organisms will have similar DNA sequences.

Geography / Biogeography � � Where the plants and animals are found / distributed around the world. Try to figure out how similar groups of organisms have dispersed to other places that are separated by huge barriers like oceans.

Embryology � � The embryos / larval stage of individuals look very similar to each other, but are drastically different when they reach adulthood. Fish, birds, reptiles, and mammals all have gill slits as embryos. In fish the gill slits become gills, mammals they become ears and throats. It is believed that the similarity in embryos in very different organisms suggest that they all evolved from a distant common ancestor.

Comparative Anatomy � Defined as the study of the structure of living and fossilized animals and the similarities (homologies) that indicate evolutionarily close relationships. �Homologous structures �Analogous structures �Vestigial structures

Homologous Structures � � � Features that are similar in structure, different in detail, but appear in different organisms and have different functions. Appearance across different species offers strong evidence for common descent. Ex- forelimb of a human, bat, and a mole. � In all of the animals the forelimbs have several bones that are similar, but the same bones vary in different animals.

Human hand Human Hand Mole foot Mole Foot Bat wing Bat Wing The question is- If each of these groups descended from a different ancestor, why would they share these homologous structures? They believe because they share a common ancestor.

Ex- Hind Limbs of Horses, Humans, and Dogs � � They are considered homologous even though the sizes of the bones are quite different in each group- due to walking differently. Humans, bears, raccoons, etc are plantigrades= walk on their whole foot, from toe to heel. Dogs and cats are digitigrades= only walk on their toes. Horses, cows, and deer are unguligrades= walk on the very tips of their toes.

Analogous Structures � � Organisms that evolved separately and are not evidence of a common ancestor but have similar structures that have similar functions. Ex- Wings of a bat and the wings of insects. � Bats are mammals, insects are Gastropods � Bats have bones, insects wings have membranes � Function evolved separately but their ancestors faced similar environmental challenges that led to these structures.

Fly wing Bat wing

Vestigial Structures � � � Remnants of organs or structures that had a function in an early ancestor but now serve no purpose or function. Ex- snakes have a tiny pelvic bone and stump like limbs. Snakes share a common ancestor with tetrapods such as lizards and dogs (considered homologous structures). Ex- Wings of ostriches. Use their wings for balance but not to fly. Lost the function of their wings because they learned to run fast and kick their predators. The gene coding for large wings was not preserved over generations.

More Examples…. � � Appendix in humans-> remnants of the cecum, part of the large intestines in plant eating mammals. Wisdom teeth in humans. Why?

Vestigial organs such as the pelvis and femur could suggest that whales migrated from land to sea.

Videos � � � https: //www. youtube. com/watch? v=x. Cxnwkj 8 f. U https: //www. youtube. com/watch? v=8 cn 0 kf 8 mh S 4 https: //www. youtube. com/watch? v=i. IGo_5 QIbx. I

NOW THAT WE UNDERSTAND A LITTLE BIT HOW THEY EVOLVE, HOW DO THEY EVOLVE AS A POPULATION? Genetic Variation Natural Selection Bottleneck & Founder effect Hardy Weinberg Equilibrium Speciation through Isolation Extinction

A population shares a common gene pool.

Genetic variation in a population increases the chance that some individuals will survive. � � � Genetic variation leads to phenotypic (ex- body size and feathers in penguins) variation. Phenotypic variation is necessary for natural selection (can be a large range from tall skinny penguins to short fat penguins). Genetic variation is stored in a population’s gene pool. � Gene pool- the combined alleles of all the individuals in a population. Different combos are caused from different animals reproducing together. � Alleles= what your chromosomes are made of. Traits.

� Allele frequencies measure genetic variation. – measures how common allele is in population – can be calculated for each allele in gene pool

� � If brown skin color became more advantageous, what would likely happen to the frequencies of alleles G and g in this gene pool? What does advantageous mean in this example?

Answers � � The G allele would decrease and the g allele would increase in frequency and become more prevalent in the gene pool. Advantageous means that the gene is more “fit” therefore the chance of passing it onto its offspring is great because it’s beneficial to the species.

Genetic variation comes from several sources. � Mutation is a random change in the DNA of a gene. – can form new allele – can be passed on to offspring if in reproductive cells • Recombination forms new combinations of alleles. – usually occurs during meiosis – parents’ alleles arranged in new ways in gametes

� Hybridization is the crossing of two different species. �occurs when individuals can’t find mate of own species �topic of current scientific research

Beefalo

Wolphin- bottlenose dolphin and false killer whale

Why do you think hybrids happen? � � � Living among similar species Can’t find a mate in their own species Humans do it to better a product / make an animal more interesting and marketable.

Natural Selection in Populations, not individuals, evolve.

Natural selection acts on distributions of traits. � A normal distribution graphs as a bell-shaped curve. – highest frequency near mean or middle value. These phenotypes seem to be the most common. – frequencies decrease toward each extreme value being the least favorable traits. –Environmental conditions can change and a certain phenotype can become advantageous (nature favors this)

Natural selection can change the distribution of a trait in one of three ways. � Microevolution is evolution within a population. � observable change in the allele frequencies over time. � can result from natural selection � There are three stages: 1. Directional 2. Stabilizing 3. Disruptive selection

Directional Selection � � � Causes a shift in a populations phenotypic distribution. A phenotype that was once rare in a population becomes more common. Ex- Antibiotic resistance ( over 200 types of bacteria have some sort of antibiotic resistance). Ex- Ostriches speed and ability to kick predators, octopus mimicking others, speed of a cheetah, the jaws and teeth of a jaguar

Stabilizing Selection � � The intermediate phenotype is favored and becomes more common in the population. Ex- height- they are mostly average, not too many that are tall and short.

Disruptive Selection � � � Supports both extreme phenotypes while the intermediate are selected against by something in nature. Ex- Feather color in the male lazuli buntings. There are bright blue headed adult males and young males that range from dull brown to bright blue. Dominant adults have the brightest blue heads and always get to choose their territory / first choice with mates. The youngest males that are the brightest blue and dullest brown win more mates than the males with bluish brown feathers. The adult, bright blue males are very aggressive towards the young bright blues and bluish brown males that they see as a threat, leaving the opportunity open for the dullest brown intermediates to win over the mates because the others are too busy fighting. The bluish brown males are not as well adapted to compete for mates because they are too blue to be left alone by the aggressive adults and not blue enough to attract the females. By favoring both phenotypes- bright blue adults and dullest brown males could lead to speciation of the bright bluish brown males.

KEY CONCEPT Natural selection is not the only mechanism through which populations evolve.

Gene flow is the movement of alleles between populations. � � Gene flow- the movement of alleles from one population to another. Gene flow occurs when individuals join new populations and reproduce. Increases genetic variation of the receiving population and keeps the neighboring populations similar. Low gene flow increases the chance that two populations will evolve into different species.

Example of Gene Flow � Bald Eagle- They are hatched and banded on the Gulf Coast of Florida. Some of these hatchlings will leave the area once they learn how to fly and migrate North. These eagles may be joining a new population.

More examples of gene flow � � � Fruit flies Plants and fungi spores Some think that hybridization is an example because it creates a new species. � Coyotes and Red wolves

Genetic Drift � � � Changes in allele frequencies that are due to chance. Causes a loss of genetic diversity in a population The allele is eliminated Most common in small populations. Two processes: Bottleneck Effect and the Founder Effect Problems it causes: � Population loses genetic variation= populations will be less likely to adapt. � Lethal alleles that are carried in the homozygous individual may be carried by the heterozygous animal, and could potentially become more common in the gene pool due to chance alone.

Bottleneck Effect � � � Genetic drift that occurs after an event greatly reduces the size of a population. Ex- Overhunting of Northern elephant seals. They were hunted to near extinction in the late 1800’s for its blubber (used to make oil). Population went to about 20 -100 individuals, but since the males are extremely territorial and fight for reproductive rights, very few males actually passed their genes on to the next generation. Now the population is up around 100, 000 , however the genetic variability in the population is very low because many alleles were completely lost during this, therefore leading to complete removal from the gene pool.

Bottleneck Effect

Founder Effect � � Genetic drift that occurs after a small number of individuals colonize a new area. Ex- Amish of Lancaster, Pa- have a high rate of Ellis-van Crevald Syndrome (type of dwarfism that is rare in other populations) and has become more common in this specific population of Amish people. This syndrome has bee traced back to the founding couples of the community.

Sexual Selection � � Certain traits increase mating success. Cost differs between sexes: �Males- produce many sperm continuously, therefore each sperm has little value. Many investments at little cost to them. �Females- limited in the number of offspring they can produce in each cycle. Each investment is valuable and they want it to turn out successful.

Sexual Selection cont…. � � The cost to the female makes them very picky about their mate. There are two types of selection: � 1. Intrasexual selection- males compete and the winner gets to mate with the female. More focused on physical and aggressive fighting behavior. Ex- Bighorn sheep � 2. Intersexual selection- males display traits that attract the female. Usually a secondary sex characteristic that tells the female they are attractive and fit. Ex- male peacock fanning out its tail.

Traits for Sex. Selection � � � Some traits may be linked with genes for good health and fertility. Some males offer traits that say he can be the better father and defend his offspring from predators. Some traits become exaggerated over time. Example- red air sacs of the male frigate bird.

Intrasexual Selection � � � Male giraffes Bighorn Sheep Elephant seals Moose Elk

Intersexual Selection � � Peacock Sage Grouse Frog calls Male guppies with bright blue and orange spots

KEY CONCEPT Hardy-Weinberg equilibrium provides a framework for understanding how populations evolve.

Hardy-Weinberg equilibrium describes populations that are not evolving. � � Biologists use models to study populations. Hardy-Weinberg equilibrium is a type of model.

� Hardy-Weinberg equilibrium describes populations that are not evolving. Genotype frequencies stay the same if five conditions are met or at equilibrium: � very large population: no genetic drift � no emigration or immigration: no gene flow � no mutations: no new alleles added to gene pool � random mating: no sexual selection � no natural selection: all traits aid equally in survival

Hardy-Weinberg equilibrium describes populations that are not evolving. � Real populations rarely meet all five conditions. � Real population data is compared to a model. � Models are used to studying how populations evolve.

The Hardy-Weinberg equation is used to predict genotype frequencies in a population. � Predicted genotype frequencies are compared with actual frequencies. � used for traits in simple dominant-recessive – must know frequency of recessive homozygote's p 2 + 2 pq + q 2 = 1 "The Hardy-Weinberg equation is based on Mendelian genetics. It is derived from a simple Punnett square in which p is the frequency of the dominant allele and q is the frequency of the recessive allele. " systems

Five Factors that can lead to evolution. � � � 1. Genetic Drift 2. Gene Flow 3. Mutation 4. Sexual Selection 5. Natural Selection Evolution is continuous, although very slow to the human eye, it is a response to changes. As environments change they can either adapt or face extinction.

Why do real populations rarely reach Hardy Weinberg Equilibrium? � Environments are constantly changing, which changes what traits are adaptive.

Would it be likely that a population of peacocks would be in Hardy Weinberg equilibrium? � No, because the females select mates based on the size of their tails-> sexual selection is occurring.

KEY CONCEPT New species can arise when populations are isolated.

The isolation of populations can lead to speciation. � Populations become isolated when there is no gene flow. � Isolated populations adapt to their own environments. � Genetic differences can add up over generations and in time the two isolated population become more and more genetically different. � Individuals may also start to behave and look differently as well.

� Reproductive isolation can occur between isolated populations. – members of different populations cannot mate successfully with one another due to different reproductive times or they are isolated by a barrier of some sort that gives them different microhabitats. – final step to becoming separate species • Speciation is the rise of two or more species from one existing species.

Reproductive Isolation Examples � I breed January to March Rana aurora and Rana boylii breed at different times. I breed March to May

Example 2 � Rana aurora (Redlegged frog) breeds in fast-moving, ephemeral streams (temporary), whereas its relative Rana catesbiana (Bullfrog) breeds in permanent ponds. (They also go through metamorphosis at different rates.

Behavioral Isolation � � � Isolation caused by differences in courtship or mating behaviors. Could be through chemical scents (ex- panda), courtship dances of birds (peacock), or songs and vocalizations (frogs and birds). Ex- over 2, 000 species of fireflies are isolated this way. Males and females produce flashes of light to attract mates of their own species. One species may emit a flash once every second, while others emit a double flash every 5. 5 seconds.

Specific Examples � � � Peacock- the faster the shake and the more eyespots= the more attractive he is to her. Long Tailed widow bird- the longer the tail the better. Flies around the grassland showing the females his long tail. Sticklebacks- females prefer males that are able to produce frequent body shakes during courtship. Leads to increased nest fanning.

Videos � � � https: //www. youtube. com/watch? v=gqs. MTZQ-pm. E https: //www. youtube. com/watch? v=Wdn. PQrqni. IE https: //www. youtube. com/watch? v=ZPFkmwo 8 DQ U https: //www. youtube. com/watch? v=6 x 4 FJse. Tn. JU https: //www. youtube. com/watch? v=f. R 7 Dqf 0 vzz. Q https: //www. youtube. com/watch? v=-zpajer. FI 1 w

� Geographic Isolation - physical barriers divide populations into two or more groups. - Rivers, mountains, dried up lakebeds. - Ex- the Isthmus of Panama created a barrier for many marine species= prevented them from crossing between the Atlantic and Pacific Oceans. - Eventually the populations became genetically different. - Ex- Snapping Shrimp- they look identical, however when males and females get together they snap at each other instead of courting. They refuse to mate with each other, therefore they formed different species.

Temporal Isolation � � � When timing prevents reproduction between populations. Reproduce at different times of the year / season. Ex- see the frog example from reproductive isolation.

KEY CONCEPT Evolution occurs in patterns.

Evolution through Natural Selection is NOT random � � Random events= mutations, genetic drift, anything that can’t be predicted. Natural Selection= not random because individuals with traits that are better adapted for their environment have a better chance of surviving and reproducing than individuals without these traits.

Convergent Evolution � � Different species must adapt to similar environments. Defined as- evolution toward similar characteristics in unrelated species. Ex- analogous structures such as wings on a bird and insects. Ex- dolphins and sharks have evolved similar tail fins that help them propel through the water even though they are separated by 300 million years.

Divergent Evolution � � Closely related species evolve in different directions. Ex- the kit fox and red fox- closely related but grew up in different environments therefore their appearances are different. � Red fox- lives in temperate forests and has a dark reddish coat that allows it to hide from predators. � Kit fox- lives in the desert and has large ears for heat regulation.

Red Fox Kit Fox Ancestor

How does convergent and divergent evolution illustrate the directional nature of natural selection? � � � Directional Selection- causes a shift in a populations phenotype (physical make-up) Convergent- a similar trait in unrelated species is selected for because of a common need / benefit the trait provides in a given environment. Divergent evolution- closely related species that are in different environments increasingly adapt to those differences with traits that are advantageous for survival in their different environments.

Are the shells of turtles and snails examples of convergent or divergent evolution? Explain. � � They are examples of convergent evolution. They do not share a common ancestor and the shells evolved as a means of protection from predators.

Species can shape each other over time. � Coevolution- two or more species evolve in response to changes in each other. � Usually a specialized relationship – mutualistic � Ex- the ant and the acacia plant. The acacia plant is covered with thorns that protect it from larger herbivores, but small insects like caterpillars can get in there and eat the sweet nectar which it produces. There is a species of stinging ants that live inside thorns and feed on the nectar. The ants protect the plant by stinging any organism that comes close and tries to eat the plant.

Coevolution can also occur in competitive relationships. � � � “Evolutionary arms race”= species respond to pressure from the other through a better adaptation over many generations. Ex- plants that produce chemicals so organisms don’t eat them. Natural selection favors organisms that can overcome the effects of the chemicals. Ex- thick shells and spines of murex snails are an adaptive response to crabs preying on them. Crabs have evolved to adapt by growing more powerful claws that are strong enough to crack the shells.

Species can become extinct. � � Extinction is the elimination of a species from Earth. Usually happens when a species can’t adapt to a change in its environment. Background Extinctions and Mass Extinctions. More than 90 % of all animals that have lived on Earth are extinct. Iberian lynx. I’m the most endangered animal in the world.

Background Extinction � � � Extinctions that occur continuously but at a very low rate. Part of the cycle of life on Earth. Occur at the same rate as speciation Usually only affect one or a few species in a small area. Caused by local changes in the environment such as the introduction of a new predator or low food supply.

Mass Extinctions � � � � More rare and intense Often occur on the global level Destroy many species, even families or orders They are thought to occur suddenly in geologic time, usually due to a catastrophic event like the Ice Age or an asteroid. Five Mass extinctions in the past 600 million years. The most studied mass extinction, between the Cretaceous and Paleocene periods about 65 million years ago, killed off the dinosaurs and made room for mammals to rapidly diversify and evolve (www. nationalgeographic. com) The causes are unsolved mysteries but they think that they may have been caused from volcanic eruptions and asteroids, global warming, mass floods, etc.

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The History of Life � Fossils can form in several ways: �Permineralization �Natural Casts �Trace Fossils �Amber Preserved Fossils �Preserved Remains

Fossils can form in several ways. � Permineralization occurs when minerals carried by water are deposited around a hard structure.

� A natural cast forms when flowing water removes all of the original tissue, leaving an impression.

� Trace fossils record the activity of an organism.

� Amber-preserved fossils are organisms that become trapped in tree resin that hardens after the tree is buried.

� Preserved remains form when an entire organism becomes encased in material such as ice or volcanic ash.

� Specific conditions are needed for fossilization. • Only a tiny percentage of living things became fossils.

� Radiometric dating provides an accurate way to estimate the age of fossils. Relative dating estimates the time during which an organism lived. � It compares the placement of fossils in layers of rock. � Scientists infer the order in which species existed.

� Radiometric dating uses decay of unstable isotopes. – Isotopes are atoms of an element that differ in their number of neutrons protrons

• Radiometric dating uses decay of unstable isotopes. – Isotopes are atoms of an element that differ in their number of neutrons. – A half-life is the amount of time it takes for half of the isotope to decay.

Index fossils are another tool to determine the age of rock layers. � Index fossils can provide the relative age of a rock layer. existed only during specific spans of time � occurred in large geographic areas � � Index fossils include fusulinids and trilobites.

Geological Time Scale Organisms Cenozoic Era- Recent Life Quaternary Includes all present life forms Tertiary Mammals, flowering plants, grasslands, insects, fishes, and birds became more diversified. Primates evolved. Mesozoic Era Cretaceous (Major Extinction) Dinosaurs peaked and went extinct, birds survived and flowering plants arose. Jurassic Dinosaurs diversified as well as early trees that are common today. Oceans were full of squid and fish. First birds arose. Triassic (Major Extinction) Following the largest mass extinction, dinosaurs evolved, ferns and cycads evolved, and mammals and flying reptiles arose. Paleozoic Era- Ancient Life Permian (Largest Mass Extinction) Modern pine trees arose and Pangaea was formed Carboniferous Coal forming sediments were laid down in swamps, fish continued to diversify, amphibians, insects, and small reptiles were around, Devonian (Major Extinction) Fish diversified. First sharks, amphibians, and insects showed up. First trees and forests arose. Silurian Earliest plants arose, glaciers melted and seas formed, and jawless and freshwater fishes evolved. Ordovician (Major Extinction) Diverse marine invertebrates and early vertebrates.

Life moved onto land during the Paleozoic Era. � � � Multicellular organisms first appeared during the Paleozoic era. The era began 544 million years ago and ended 248 million years ago. The Cambrian explosion led to a huge diversity of animal species. All life was found in the ocean.

• Life moved onto land in the middle of the Paleozoic era.

Reptiles radiated during the Mesozoic era. � � � The Mesozoic era is known as the Age of Reptiles. It began 248 million years ago and ended 65 million years ago. Dinosaurs, birds, flowering plants, and first mammals appeared.

Mammals radiated during the Cenozoic era. � � • The Cenozoic era began 65 million years ago and continues today. Placental mammals and monotremes evolved and diversified. Anatomically modern humans appeared late in the era.