GRADE 11 U LEVEL BIOLOGY ENTIRE EVOLUTION UNIT

Relative Dating

Determines the age of a fossil by comparing its position to the layers of the sedimentary rock around it, following that newer rocks form on top of older rocks.

Radiometric Dating

Provides an estimate of the actual numerical age by measuring the rate of radioactive decay (half-lives of elements such as Carbon-14) found within the sample.

Homologous structures

Body parts that look similar across different species but may serve different functions. For example, the forelimbs of mammals (humans, dogs, birds, & whales) all share the same bone arrangement—one bone (humerus), 2 bones (radius & ulna), wrist bones (carpals), and finger bones (metacarpals + phalanges). These similarities provide evidence of a common ancestor.

Transitional Fossil

An organism that was a mix of two different types of organisms, showing evidence of an evolutionary jump!! For example Tiktaalik—a fossil that had features of a fish (fins, scales, gills) and a tetrapod (eyes on top of head, flattened body, digits on its forelimbs, neck).

Vestigial structures

Remaining body parts that have been passed down (as a species evolved) and do not serve a purpose currently (lost original purpose). Examples 1. Wisdom teeth, 2. Appendix, 3. Dew claw.

Embryology

Study of the development of embryos across different species.

Embryo

Name doctors & scientists give to an organism before it's born or hatched. Main structures Notochord whichdevelops into backbone, Nerve chord which develops into a spinal cord, Pharyngeal pouches which are gill slits on some animals, same passage ways part of thyroid (some vertebrates)Postanal tail which is the human tail bone. In their early stages of development, all vertebrate embry

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Microevolution

Studies how mutation & natural selection acts on populations of organisms.

Macroevolution

Focuses on large evolutionary changes, like how a dinosaur species evolved into modern birds over tens of millions of years.

Gene flow

Describes that the genes are shared in an interbreeding population. In order to make another generation of offspring, the parents' genes mix during sexual relationship.

Genetic drift

A change in the allele frequency of a population as a result of chance events rather than natural selection.

Bottleneck effect

A sudden reduction in the number of alleles in a population (Eg. disease—killing many individuals = reduced genetic diversity).

Founder effect

Change in allele frequencies as a result of the migration of a small subgroup of a population. For example, a few individuals colonize a new habitat (reduced genetic diversity).

Gene pool

Total collection of all the genes and their different alleles (variations) present within an interbreeding population.

Mutation

Occurs when DNA is not copied properly; necessary for evolution, it is the ultimate source of all knew [sic] genetic variation in a population.

Bipedalism

Ability of an organism to walk upright on two legs (primary mode of locomotion).

Hominid

Any member of the biological family Hominidae, which includes modern humans, extinct human species (like neanderthals), and all of our immediate evolutionary ancestors.

Fossil

The preserved remains, impressions, or traces of any once-living organism from a past geological age (older than 10,000 years).

Stabilizing Selection

When selective pressures select against 2 extremes of a trait.Ex Plants that are too short might not get enough sunlight in a forest. Plants that are too tall might get damaged by the wind. In this case, medium height plants would be favored.

Directional Selection

When one extreme of the trait is selected for.Ex In giraffes, short necks are selected against because giraffes with short necks cannot reach the higher leaves. Only long necks will be favored and become more prominent within the population.

Disruptive selection

Selective pressures act against individuals with the intermediate phenotype. The two extreme phenotypes are favored.Ex In a stream, small fish are hard to see & catch. Medium sized fish are easy prey for larger fish. Large fish don't have many predators & survive well.

Adaptation

A structural, behavioral, or physiological process that helps an organism survive & reproduce in a particular environment.Note! Not every trait is an adaptation. They are products of natural selection

.Variations

Differences between individuals in a species (can be harmful).Note! A favorable variation can become an adaptation.

Speciation

Process of forming new species from a species already in existence. It requires a population to be isolated from the original population. Then in the two isolated groups, the species breed among themselves, and genetic changes accumulate over time, which means reproductive isolation has occurred.

Reproductive Isolation

The evolutionary mechanisms, behaviors, or physiological processes that prevent individuals of different species from interbreeding and producing fertile offspring.

Structural A

Physical features that allow an organism to be well suited to its environment.

Behavioral A

When an organism is adapted to how they respond to the environment.

Physiological A

associated with functions in organisms.

1. Prezygotic Mechanism

1. (Before zygote forms). Occurs through three ways of reproductive isolation

Geographic isolation

Two populations become separated by a physical barrier (canyon, river, lake) preventing the two populations from breeding.

Temporal isolation

Where two species whose ranges overlap have different periods of sexual activity or breeding seasons.

Behavioral isolation

Two populations become isolated by differences in courtship rituals or other behaviors.

2. Postzygotic Mechanism

(After zygote forms) Zygotic mortality which is when Embryo dies.Hybrid infertility which is when Offspring live but cannot breed (e.g., mule).Hybrid inviability which is when Offspring fail to develop properly.

Allopatric Speciation

The formation of a new species that occurs when a population is split into two or more isolated groups by a geographic barrier (Geographic isolation).

Sympatric Speciation

The formation of a new species that occurs within the same geographic area (Behavioral/Temporal isolation).

Age of Earth

4.54 billion years old.

How Antibiotic Resistance Evolves in Bacteria

Evolves through natural selection. Individual bacteria undergo random mutations & sometimes one grants resistance to a specific antibiotic. When antibiotics are used, the bacteria that are non-resistant die, but the resistant bacteria survive & then reproduce and pass the resistant gene to their offspring, creating more resistant bacteria. Bacteria can also spread resistance genes to other bacteria through a process called conjugation.

Species

A group of organisms that can breed with one another.

Genetic Bottleneck Effect

Occurs when a catastrophe (starvation, disease, etc.) drastically reduces the population size. The survivors have less genetic variation, and the resulting new population reflects only that limited genetic pool.

Genetic Founder Effect

Occurs when a small group of individuals (founders) leaves a large population to start a new one (e.g., on an island). The new population's genetic makeup is determined by the specific alleles of the founders.

Gene Flow

The movement of genes in or out of a population. This can happen through movement of a population or through movement of gametes (e.g., pollen or fish eggs). This can bring new alleles or affect the frequency of existing alleles in a population.

Eugene Dubois

(1891)Discovered Java man on the island of Java in 1891.Predicted that the "missing link" between apes & humans would have a brain half the size of a modern human & twice the size of a chimpanzee.Missing link name

3 FACTS ABOUT H. ERECTUS

1) stone tools were advanced

2) learn to care for sick and injured

3) ability to tame fire, they could use fire for heat, light and protection

Donald Johanson & Tom Gray

(1974)Discovered "Lucy" (Australopithecus afarensis) (3.2 million years ago).Had nearly 40 pieces of fossilized skeleton.First evidence of bipedalism then Walking upright freed hands to become a maker and user of tools. This provided greater access to protein from scavenging and hunting. A high protein diet fueled their brains to grow.Rare find because early hominins didn't bury their dead so often; scavengers would carry bones far away.

Charles Darwin

(February 12, 1809, England))Mechanism Natural SelectionSummary: Variations exist within a population; organisms with traits best suited (fit) for their environment are more likely to survive & reproduce, passing those traits to the next generation.Example Tortoises on different islands had different shaped necks because of the various environments/food sources; traits that made it easier to get food allowed them to live & reproduce.

Jean-Baptiste Lamarck

(August 01, 1744, France)Mechanism Inheritance of acquired traits.Summary Organisms "change" during their lifetime based on use or disuse of "inner need." These inner physical changes are then passed directly to their offspring.Example Giraffe He argued most short-necked ancestors stretched their necks to reach high leaves & these long necks were inherited by their young.

Charles Lyell

Proposed uniformitarianism, Earth changes slowly over long periods.Influenced Darwin by showing that the Earth is old enough for evolution to occur.A geologist.

Raymond Dart

(1924)Unveiled a brain & skull of ape-man.Taung child (\rightarrow ) Australopithecus africanus.Significance: place the ancestral home of hominids firmly in Africa

Louis & Mary Leakey

(1959)Found both Zinjanthropus & Homo habilis.Showed a co-existence of hominin species (lived at the exact same time).Changed the model of human evolution from being linear to branched. (Homo hais was the start of tech, tool maker)

Charles Dawson

(1912)Piltdown man wascelebrated as the missing link.A FRAUD!Modern ape skull had been filed down to look human. when drilled into drop bone it smelled like burnt flush, which indicates that it wasn’t very old.

Q1) There are several major milestones in human evolution. These milestones include bipedalism, increased brain size, and tool use.a) Order these milestones from first to most recent -->Bipedalism,Tool use,Increased brain size.

Bipedalism, tool use, increased brain size

Explain how the main 3 milestyones let to the other

Walking upright freed hands; they used their hands to make tools and use them to hunt & cut up food. They had more access to protein-rich foods that fueled their brain to grow.

Q4) With the use of an example, explain how a reduction in gene flow can result in speciation

Can people can be reduced by a number of reasons. One could be geographical isolation. If a group of wolves were geographically isolated, 13 pool is now reduced they can only interpret with those in their population. A mutation may arise in one population however it will not be shared with the other other population due to the physical barrier affecting the gene flow This says species may become two genetically distinct and can no longer interbreed if they were back together becoming separate species, which is speciation.

Gene flow can be reduced by geographic isolation. If a group of individuals is isolated, their gene pool is reduced and they can no longer interbreed with the original population. Mutations occurring in one population will not be shared with the other. Eventually, they may become so genetically distinct that they can no longer interbreed, becoming separate species.

Compare & contrast the founder effect and the bottleneck effect. State 2 similarities & an Example to compare

FOUNDER EFFECT,Few individuals colonize a new habitat .Ex, A group of lizards go off on their own to a new island, abandoning main population. They are the largest predator & grow very large - too distinct from main populations becoming separate species. SIMILARITIES, Reduced genetic diversity, Creates small populations of new species by chance. BOTTLENECK EFFECT, Caused by disasterEx. Step down by only 5% of the original population remains with a smaller chain full different from the original population. ThE ants are very different and become separate species.

Q12) With the use of an example, describe Darwin's theory of evolution by natural selection

Darwin went on his voyage on the HMS beagle and noticed variation amongst finches depending on the islands they lived on. Some had better beaks for their island that better suited their environment & the food around them they had the favoured trait. Therefore, Darwin proposed the idea of "survival of the fittest" meaning the organisms most fit, like the finches with better beaks, would reproduce more offspring & survive longer. Their favourable trait would be passed down to their offspring, who would also have it. That's how the trait is selected naturally, through successful reproduction.